Machines and devices of chemical industries and enterprises. Machinery and apparatus for chemical industries and building materials enterprises

Scope of machines and apparatuses of chemical production

Training is carried out in educational institutions:

With specialty of higher educationIstepsand

The training of a specialist in this specialty involves the formation of certain professional competencies, including knowledge and skills in organizing and managing the entire range of maintenance and repair work. technological equipment chemical industries and enterprises of building materials; development and design normative documents organizing and carrying out repairs and installation of equipment; planning, management and organizational support of activities; training of personnel for work at chemical enterprises, production of building materials, etc.

mechanical engineer».

Objects professional activity specialist are:

Machines, devices, technological installations of chemical and pharmaceutical industries and enterprises building materials;

Design, technological and management documentation;

Specialized tools and means of mechanization of repair and installation works;

Special software.

Engineer;
Research Engineer;
Controller engineer;
Mechanical engineer;
Implementation Engineer new technology and technology;
Equipment completion engineer;
Mechanization and automation engineer production processes;
Adjustment and testing engineer;
Tool engineer;
Technical Supervision Engineer;
Design engineer;
Constructor.

Specialty of secondary specialized education

The specialty provides a qualification Mechanical Technician».

The area of professional activity of a specialist is:

chemical enterprises;
oil refining industry;
building materials enterprises;
specialized repair and assembly organizations.

After graduation, graduates of the above specialty can occupy the following positions:

Technician;
Technician for adjustment and testing;
Equipment maintenance and repair technician.

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EE "Belarusian State Technological University" - Machinery and apparatus for chemical industries and building materials enterprises- part-time - >>>
EE "Belarusian State Technological University" - Machinery and apparatus for chemical industries and building materials enterprises >>>
- Machinery and apparatus for chemical industries and building materials enterprises- days - >>>
UO "Polotsk State University" - Machinery and apparatus for chemical industries and building materials enterprises- correspondence reduced term - >>>

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- Machinery and apparatus of chemical production and building materials enterprises (maintenance and repair of equipment of chemical and oil refining enterprises)- days - >>>
Educational Establishment "Novopolotsk State Polytechnic College" - Machinery and apparatus for chemical industries and building materials enterprises (maintenance and repair of equipment for chemical and oil and gas processing enterprises)- part-time - >>>
Technological College of Educational Establishment "Grodno State University named after Ya. Kupala" - Machinery and apparatus for chemical industries and building materials enterprises- days - >>>
Branch of BNTU "Salihorsk State Mining and Chemical College" - Machinery and apparatus for chemical industries and building materials enterprises- part-time - >>>
State Educational Institution "Bobruisk State Mechanics and Technology College" - Machinery and apparatus for chemical industries and building materials enterprises- days - >>>

Introduction

Status, direction and prospects for the development of repair services at building materials enterprises.

The state and prospects for the development of repair services at building materials enterprises are completely dependent on financial condition and the quality of these enterprises. Successfully operating enterprises have financial and material resources to ensure high-quality work and development of their repair services by replacing and modernizing outdated technological equipment, acquiring modern repair equipment, materials, and spare parts. Poorly functioning enterprises due to lack of material and financial resources cannot provide repair services with everything necessary, which negatively affects their work and development.

At present, the main directions of development of repair services of building materials enterprises are:

1) increasing the level of their mechanization, which improves the productivity of repair workers;

2) the introduction into practice of modern advanced technologies for the repair and restoration of faulty machine parts, which increases their reliability and durability, reduces the accident rate;

3) improvement of the organization of repairs and maintenance of technological equipment through the use of advanced methods and techniques for repairing machines;

4) widespread use of substitute materials for expensive non-ferrous metals and alloys in the repair of equipment;

5) tightening the quality requirements for used spare parts, repair materials and performance of repair operations;

6) improving the quality of repair work by improving the qualifications of repair personnel through various forms learning.

The role and importance of repair services for the quality of enterprises

The sustainable and successful operation of enterprises depends on the condition and quality of the technological equipment. Technological equipment that is in good technical condition has a low accident rate, a high utilization rate and performance indicators, and produces high quality products. This allows the enterprise to work rhythmically, produce a large volume of products with a relatively low cost, since the cost of maintaining the equipment falls on the cost of production, which ultimately makes it competitive in the market. The poor technical condition of the technological equipment has a negative impact on the work of the enterprise as a whole: its frequent accident rate reduces the volume of output, which ultimately makes it competitive in the market.

The poor technical condition of the technological equipment has a negative impact on the work of the enterprise and therefore its frequent accidents reduce the volume of products, and the poor technical condition reduces the level of its quality and increases the cost, as the costs of eliminating accidents increase.

Since the main task of the repair services of building materials enterprises is to maintain technological equipment in good condition, therefore, the quality of their work directly affects the quality of the work of enterprises as a whole.

The Importance of Quality Overhauls to Machine Longevity

Overhauls of machines are carried out in order to restore the efficiency lost during operation due to wear and tear of other malfunctions of parts and assemblies. High-quality overhauls increase the reliability and durability of machines, as I restore gaps and tightness in the interfaces of parts and machines as a whole. Therefore, the durability of machines can be increased only by improving the quality of their operation, maintenance and repairs.

1. General part

1.1 Brief description of the enterprise and its work

JSC "Krasnoselskstroymaterialy" is largest manufacturer building materials in the Republic of Belarus. Its basis is cement factory, producing about 1.5 million tons per year. In addition to it, the OJSC includes:

1) plant of asbestos-cement products, producing 1160 kilometers of conditional asbestos-cement pipes, 112.8 million conditional asbestos-cement corrugated sheets, 60 thousand m of paving slabs, 50 thousand tons of dry building mixtures and 100 tons of polyethylene film per year;

2) a lime plant producing 431,000 tons of lime and 70,000 tons of finely granulated chalk per year.

The products of OJSC "Krasnoselskstroymaterialy" are in great demand both within the country and in the countries of near and far abroad. The technological equipment of the enterprise operates in difficult conditions as part of production production lines, therefore, very large funds are spent on maintaining it in working condition.

1.2 The organization of major repairs of equipment existing at the enterprise

The repair base of OJSC "Krasnoselskstroymaterialy" is a mechanical repair shop, which performs major repairs of technological equipment. Overhauls are carried out according to annual and monthly schedules developed by the department of the chief mechanic. The chief mechanic of the enterprise is responsible for their preparation and implementation. Machines for overhaul are accepted by a commission chaired by the chief engineer of the enterprise, consisting of: the chief mechanic and the chief power engineer, the mechanic and the head of the workshop that owns the machine and the repair manager appointed from the engineering and technical workers (ITR) of the RMC. The same commission accepts the repaired car for operation.

1.3 Application, purpose and operating conditions of the machine, their influence on the wear of parts. List of wearing parts

A drying drum at the cement plant of OAO Krasnoselskstroy-materialy is used for drying granular slag, which is added to the clinker when it is ground to cement. It is installed outdoors. Its parts work under conditions of variable loads, and the body - at high temperatures and material moisture. This adversely affects their strength due to oxidation and also causes abrasive wear. High-wear parts of the dryer drum include: drum body, transfer shelves, gear wheels, bearings, roller axles, shafts.

1.4 Substantiation of the theme of the graduation project

There are a number of shortcomings in the organization of capital repairs of technological equipment at OAO Krasnoselskstroymaterialy: the need for workers and repair equipment to perform repairs is not calculated, therefore, the downtime of machines for repairs is not maintained; the technology of disassembly, assembly of machines and repair and restoration of their parts and assemblies is not developed in detail; repairs are not always carefully prepared, which negatively affects their quality and timing. Since the topic of the graduation project is aimed at eliminating these shortcomings, it is relevant for the enterprise.

2. Organizational part

2.1 Choice of method and method of overhaul

In the building materials industry (PSM), impersonal and non-impersonal methods and detail, nodal, aggregate-nodal, aggregate, block and machine-shift methods of repairing machines are used. The choice of method and method depends on the design of the machine and their total number used in this workshop, the form of organization of repair services. Since OJSC Krasnoselskstroymaterialy has a repair stock of spare parts, components and assemblies of the machine (reducers, shafts, their assembly units and parts) the most suitable for the overhaul of the dryer drum will be the impersonal method and the aggregate-nodal method, which we take as a basis. With the chosen method, the repair of the dryer drum consists in the fact that faulty components and assemblies (rollers, girth gear, etc.) are replaced with new or repaired ones, prepared in advance, taken from the repair fund. At the same time, the downtime of the machine in repair is reduced and the category of repair work is reduced. The impersonal method consists in the fact that defective parts, components and assemblies are removed from the machine and sent for repair to the mechanical repair shop (RMC) and are no longer installed on this machine. It also reduces machine downtime, improves quality and reduces labor costs for repairs.

2.2 Machine overhaul network schedule

Fig 2.2 Network diagram of the overhaul of the dryer drum.

Building a network schedule for the overhaul of a machine, determining the duration of the repair allows you to visualize the entire repair process. Shows the sequence of operations and their relationship. It makes it possible to determine the complexity of repair work and the downtime of the machine in repair.

Table 1. List of works for overhaul dryer drum

	Number and name repair work	Labor capacity, h/h	Number of performers	Execution time, hours	Symbol
	Cleaning, washing, troubleshooting of the drum body, transfer shelves, bandages and roller supports
	Repair of the drum body, transfer shelves, bandages and idlers
	Dismantling the drive and lubrication system
	Removing the drum seals
	Dismantling the drum
	Dismantling of idlers
	Cleaning, washing, troubleshooting of foundation slabs
	Foundation slab repair
Roller installation
Installing the drum
Installation of seals
Installing the drive and lubrication system
Run-in and testing of the machine, commissioning
Disassembly of the drive and lubrication system into parts, their cleaning, washing, troubleshooting
Repair of drive parts and lubrication system
Assembly of the drive and lubrication system
Cleaning, disassembly, washing, troubleshooting of seals
Seal repair
Cleaning, washing, troubleshooting and disassembly of the drum rollers
Roller repair
Roller assembly

We build a network schedule according to table 1. We write out from the network schedule for the overhaul of the dryer drum all possible ways to repair the machine:

1 way - L1 - (1-2) - (2-3) - (3-4) - (4-5) - (5-6) - (6-7) - (7-8) - (8- 9) - (9-10) - (10-11) - (11-12) - (12-13) - (13-14);

2 way - L2 - (1-2) - (2-3) - (3-4) - (4-15) -(15-16) - (16-12) - (12-13) - (13- fourteen);

3 way - L3 - (1-2) - (2-3) - (3-4) - (4-5) - (5-6) - (6-7) - (7-18) - (18- 19) - (19-9) - (9-10) - (10-11) - (11-12) - (12-13) - (13-14);

4 way - L4 - (1-2) - (2-3) -- (3-4) - (4-5) - (5-17) - (17-11) - (11-12) - (12 -13) - (13-14);

We determine the idle time (rotor) of the dryer drum on each of the paths:

t(L1) =1+20 +1+1+1+1+1+7+2+1+1+6+ 48 -91h;

t (L2) = 1 + 20 + 1 + 2 + 8 + 3 + 6 + 48 = 89 h;

t(L3) =1+20 +1 + 1 + 1 + 1+3 + 8 + 3 + 2+1 + 1+6 + 48 = 97 h;

t (L4) = 1 + 20 + 1 + -1 + 1 + 1 + 1 + 6 + 48 = 80 hours;

The path (L 3) is critical, because it has the longest time and its time is taken as the calculated one: t (L3) = tnp = 97 hours.

2.3 Calculation of the labor intensity of repair work

We determine the actual labor intensity of plumbing and welding work during one major overhaul

where Tk is the total standard labor intensity of one overhaul Tk = 800 people.h. (L-4) - S. 184.

nrazb, nsb, ncv - the percentage of labor intensity, respectively, of disassembly, assembly and welding works from the total; nraz = 14%, nb = 16%, ncv = 12%.

K1 - coefficient taking into account the life of the machine; accept K1 = 1.1;

K2 - coefficient taking into account the location of the repair; we accept K1 = 1.2 - when repairing outdoors;

K3 - coefficient taking into account the temperature of the medium; accept K1 =1. (L - 4) - S. 19, table 1.

Tsl \u003d 0.01 × 960 × (14+ 16) × 1.1 × 1.2 × 1 \u003d 317 people;

Tsv \u003d 0.01 × 800 × 12 × 1.1 × 1.2 × 1 \u003d 127 man.h.

We determine the total labor intensity of plumbing and welding works according to the formula:

Ttot \u003d Tsl + Tw \u003d 317 + 127 \u003d 444 people.h.

2.4 Calculation of the need for workers to perform a major overhaul

Determine the idle time of the machine in days:

tnp = tnp / 8 × n cm

where p cm - shift work of repair teams; accept n cm = 3;

tpr = 97/ 8 × 3 = 4 days.

We determine the time fund of one locksmith and welder for the entire repair period:

Fsl = Fsv = 8 × tnp = 8 × 4 = 32 h

We determine the number of locksmiths and welders:

mp.cl. = Tsl/Fsl; mr.sv. = Tsv / Fsv;

mr.sl. = 317/32 = 10.4;

accept tr.sl. = 10 people; tr.sv. \u003d 127 / 30.6 \u003d 4 people. We determine the composition of the teams:

1st brigade - 4 locksmiths and 2 welders;

2nd brigade - 3 locksmiths and 1 welder;

3rd brigade - 3 locksmiths and 1 welder.

2.5 Selection of repair equipment

For a successful overhaul of a tumble dryer, it is important to provide it with the necessary repair equipment. His selection is made below.

For dismantling and installation of parts, components and assemblies and their movement during disassembly and assembly of the dryer drum will be used. Boom crane on pneumatic wheels with a lifting capacity of 250 KN and hydraulic jacks with a lifting capacity of 1000 KN. To hook them, load-handling devices corresponding to their weight will be used.

To perform electric welding work by two welders in each team, we select two welding machines: one is AC STAN 700, and the other is DC PSO-300. To perform gas-cutting work for each team, we select:

1) one set of gas-cutting equipment;

2) cylinders for oxygen and propane-butane - as needed;

3) a trolley for transporting gas cylinders - one for all teams.

To protect the place of electric welding, we select two portable shields. Washing bath OM-13-16 will be used for washing parts. To store rags, a sealed metal box will be used, divided by a vertical partition into two compartments - for fresh and

Used rags. Two metal racks will be used to store small parts removed from the machine and new ones. For installation on the repair site of the idlers removed from the machine, cages from wooden sleepers will be laid out. According to the rules fire safety a fire shield equipped with fire equipment and a sand box will be installed at the repair site. Hydraulic jacks and pullers will be used to dismantle the units and assemblies of the dryer drum. A manual portable electric grinder will be used to clean the welds and burrs (seizures) on the parts. An electric drill will be used to drill holes in the parts.

2.6 Work to prepare the overhaul of the machine

The successful completion of a tumble dryer overhaul largely depends on its preparation. Preparation work includes:

- Drawing up lists of defects of its nodes. They are made up when the dryer drum stops for current repairs and technical services(THEN).

– Determining the scope and range of work for the upcoming overhaul based on the data of the list of defects.

- Drawing up a cost estimate for the upcoming overhaul, development of technological maps for the repair and restoration of faulty parts and assemblies that will be replaced during the repair, their drawings.

– Manufacture or purchase of materials and spare parts that will be required for the overhaul. After manufacturing or purchase, they must pass technical quality control, delivered to the repair site and prepared for storage before the start of repair.

- The preparation of the repair site, in which all foreign objects are removed from it, is fenced off. They supply compressed air and water, equip posts for connecting repair equipment.

– Delivery of repair equipment to the repair site, its installation, inspection, connection and testing in operation.

- Creation of repair teams from the workers of the RMC and their instruction in safety precautions when performing repair work, fire safety and repair technology.

- Development of a schedule for the overhaul.

Immediately before stopping for a major overhaul, the dryer drum must be cleaned from the outside and inside of material residues, dirt and oil and disconnected from the mains.

2.7 Handing over the machine for repair

The dryer drum is handed over for overhaul in accordance with the annual and monthly schedules of repairs and maintenance of the equipment by the head of the owner's shop. It is accepted for repair by a commission chaired by the chief engineer and chief power engineer, a representative of the safety department, a shop mechanic and a major overhaul manager. The commission checks how the repair is prepared, inspects the dryer drum, and, with satisfactory results, accepts it for repair. Acceptance is formalized by an act of the form established by the STOiR, which is signed by all members of the commission. If the commission finds any shortcomings in the preparation of the repair, it postpones the acceptance period and issues an order to those responsible for the preparation (chief mechanic) to eliminate the identified shortcomings.

2.8 Acceptance of the machine from repair and commissioning

The dryer drum is accepted from repair after running in and testing by the same commission that accepted it for repair. The commission gets acquainted with the act of running-in and testing, inspects the machine, evaluates the quality of repair and assembly, and accepts the dryer drum for operation with a satisfactory assessment of the quality of the repair. Acceptance is formalized by an act signed by all members of the commission. If any shortcomings are found during acceptance, the commission sets a new acceptance date.

3. Technological part

3.1 Cleaning, washing the machine, its parts, components and assemblies

Cleaning and washing of the tumble dryer outside and inside its body is carried out by the technological personnel serving it in preparation for repair. For this, crowbars, shovels, metal scrapers and brushes, rags, pressurized water and compressed air from rubber hoses are used. In the process of repairing the dryer drum, cleaning and washing of units, units and parts is carried out in several stages: after removing them from the machine, disassembling the units into units and units -for details. This is done in order to carry out their high-quality troubleshooting and repair, since dirt, rust and grease make it difficult to carry out such work. Dirt is first removed from large parts and assemblies of the dryer drum (rollers, their frames, housing, drum, bandages, bearing housings) with shovels, crowbars, scrapers, then blown with compressed air. Relatively small parts and assemblies are washed in a washing bath installed at the repair site, in kerosene or diesel fuel and washing solutions manually using rags. Rust is removed with solutions of 25% hydrochloric acid with the addition of 1% zinc, keeping for 2-3 hours, carbon deposits are removed by soaking parts in a bath with a solution of soda ash and caustic soda, soap at a temperature of 80-90 ° C, after which they are washed first in cold, and then in hot water or treatment with steel brushes, scrapers.

3.2 Machine disassembly technology, equipment and tools used

To disassemble the dryer drum, a boom crane with a lifting capacity of 25 tf, hydraulic jacks with a lifting capacity of 100 tf, portable inventory scaffolding Q - 5tf, screw pullers and, for disassembling the removed units, equipment of the repair and mechanical workshop of the enterprise are used. It is disassembled in the following order: fuel supply and combustion system - electric motor - gearbox - guards - girth gear and girth gear, - drum housing seals - drum housing - roller supports. Roller frames are repaired at the installation site.

At the ring gear, the bolted connections of fastening the upper half to the body and to the second half are first disassembled (for this, the drum is turned by the drive before disassembly so that the plane of its separation is horizontal), then the upper half is removed and placed on sleeper cages at the repair site. Then the winch ropes are wound around the body, fixing their ends on the body, and turning it by 180 °. And they do the same with the other half. The drum body is removed as follows: four hydraulic jacks are installed under it, two prefabricated steel belts are laid on them, it is raised with jacks to a height of 150-200 mm, cages of wooden beams are placed under the belts and belts are lowered onto them.

The roller bearings are first disconnected from the frame, their adjusting devices are disassembled and their bearing housings are moved from the drum axis along the frame guides with winches or jacks and then removed from it.

3.3 Troubleshooting parts and assemblies, tools used

Troubleshooting parts is called the establishment of their technical condition. For this, inspections and measurements with instruments are used.

The drum body may have the following defects:

Wear of the inner surface, cracks. To determine the wear to the wall of the drum parallel to the axis is applied straightedge and a measuring ruler measure the gaps between their surfaces. Separate sections of the hull with wall wear of more than 20% of their thickness are rejected. Cracks are determined visually. Parts of cellular heat exchangers and transfer shelves inside the drum may have wear, bending and twisting, determined visually or by measuring their thickness with calipers, rulers.

Tires can have wear in the form of rolling and peeling of the rolling surfaces, scuffing and cracks. The amount of wear is determined by measuring their thickness with rulers and diameters in 3 sections (along the edges and in the middle), for which the tape measure is wrapped around the bandage and the circumference is measured. The circumference can be measured while the drum is running by applying calibrated rollers to the tread surface. Peeling is determined visually. Seizures and cracks are determined visually. Bandages are rejected when wear exceeds 20%.

Support and thrust rollers can have wear on the bearing surface, resulting in ovality and taper, scoring and cracks. Their wear is determined by measuring the diameters of 3 sections with a tape measure, the ovality and taper are calculated. The rollers are rejected with cracks deeper than 20% of the ring thickness and its reduction due to wear also by 20%.

The crown and crown gears wear, chip and break the teeth, and scuff on their surfaces, which form cracks: on the rim. Tooth wear is determined by measuring their thickness with a caliper or template and a set of probes. If the teeth are worn more than 30%, the gears are chipped and broken, they are subject to rejection. The gears of the gearbox have the same faults.

The landing surfaces of the crown gear, rollers, gears of the reducer, couplings may have wear, scoring, ovality and taper, cracks on the hubs.

Wear is determined by measuring their diameters with a caliper, other defects - visually. Rejected with wear, above the allowable, and through cracks. Keyways may have flank wear, which is measured with templates and a set of feeler gauges.

Rolling bearings can show wear in the form of shells of ring surfaces, rolling elements / cracks, destruction, crushing, cracks and destruction of cages. Crushing, cracks are determined visually, and wear is determined by measuring the beating of the outer rings relative to the inner ones in the fixtures with dial indicators. In case of wear exceeding the allowable (determined according to the tables), cracks and breakages, the bearings are rejected.

Idle frame frames can have corrosion, bending and twisting of individual elements. Cracks and breakage. Bending and twisting is determined by measuring the gaps with a measuring ruler, between the surfaces of the elements and the calibration ruler applied to them, the remaining defects are visualized.

The drive shaft, gear shafts and roller axles may have the following faults:

1) wear of the working surfaces of the necks, scoring, wear of the walls of the keyways, scoring on them, wear of the slot;

2) wear of threaded surfaces, crumpling and stripping of threads;

3) twisting of the necks, bending of the axes.

To determine the wear of the necks with a micrometer, measure their diameters in 3 sections (at a distance of 5 mm from the ends and in the middle) in the vertical and horizontal planes, calculate the ovality and taper and compare with the allowable ones determined from the reference tables.

The wear of the side walls of the keyways in the form of crushing is determined by measuring their width with a caliper and comparing with the drawing dimensions, or using templates and sets of probes. Spline wear is measured with templates and a set of feelers. Seizures are determined visually during inspection.

Thread wear is determined by checking them with thread gauges, and thread breakage is determined visually.

The bending of the shafts is determined by measuring with dial gauges. To do this, the shaft is fixed in the centers of the lathe or the necks are laid on prisms mounted on the calibration plate. The indicator is fixed in a tripod, which is mounted on the guides of a lathe or a surface plate.

The measuring rod of the indicator is brought to the shaft, the indicator needle is set to zero by turning the scale, and by turning the shaft by 90°, 180°, 270° and 360°, the indicator readings are recorded. The largest of them will be equal to the magnitude of the shaft bend.

The twisting of the necks is determined by setting the keyways horizontally and measuring the height position of their ends with a gage gauge.

3.4 Technology of repair and restoration of parts

Repair of the dryer begins with measuring the deviations of the axis of its body (break), provided that the roller supports do not require replacement. Measurements are made with a level; and according to their results, the position of the rollers relative to the axis of the drum body is adjusted.

In case of defects in sections of the drum body and bandages that cause rejection, they are replaced. To do this, circles are applied with chalk, along which the body and the removed section will be cut (its slings and slings are hung on the crane hook), the drum is cut with gas burners in circles and the damaged area is removed, and a pre-made new one is installed in its place and after centering with the axis of the drum , they are grabbed by electric welding to the remaining parts of the body, the supports are removed and, turning the body with a drive, they are welded to them with a welding wire using automatic welding machines. Cracks that do not cause rejection of the drum body are drilled at the ends with a 2-5 mm drill, chamfered and welded with a high-quality electrode, or a steel patch is applied to it and welded to the body. Parts of cell heat exchangers and bulk shelves in case of wear, bending and twisting exceeding the allowable ones are cut off with a gas burner and new ones are welded by electric welding. Wear of bandages and rollers during the first repairs is eliminated by fine turning. To do this, portable turning devices are fixed on the frame and roller supports and, using a drive for rotation, they grind the rollers and bandages to the repair dimensions, after which they check and adjust the position of the rollers. Cracks at rollers and bandages with a depth of less than 20% of their thickness are welded in the same way as at the drum body.

During the first repairs of the dryer drum, when the teeth of the crown and girth gears and the gear wheels of the gearboxes, having an axis of symmetry not exceeding 30%, are worn, they are rotated on the shafts by 180 °. With wear over 30% and other defects - replace.

Shallow scratches (less than 0.5 mm) of the working surfaces of the teeth, bandages, rollers, shaft necks are cleaned with velvet files, abrasive skins, and deep ones are melted by welding and cleaned with a grinding wheel. In case of wear of the mounting surfaces of the crown gear, gear wheels of reducers, rollers, couplings, they are manually deposited by electric surfacing with electrodes that are similar in composition to the steels of these parts, annealed, bored on lathes and ground on internal grinding machines. When the keyways are worn, they are melted, cleaned with a grinding wheel and a new groove is cut against the welded one.

Worn shaft journals are welded by semi-automatic welding in a shielding gas environment or by manual electric welding with high-quality electrodes and, after annealing, they are turned and ground on turning and grinding machines. Threaded necks are machined and cut into threads of nominal size. Curved shafts and axles are straightened under pressure, preheating them to 600°-700°C. When twisting the shafts above the allowable, they are discarded. Seizures on the necks are cleaned with "velvet" files and sandpaper. Rolling bearings with extremely unacceptable faults are not restored.

Defective elements with deformations exceeding the permissible ones are corrected with heating or cut off with a gas burner and welded in advance prepared. Cracks are welded by electric welding.

For high-quality overhaul of the dryer drum, it is necessary to apply the list of defects of its components, technological maps repair and restoration of parts, "repair" drawings.

3.5 Assembly, run-in and testing of the machine

The tumble dryer is assembled in the reverse order of disassembly (see paragraph 4.2.), and the same equipment is used. The repaired parts of the roller bearings, drives are first assembled into assembly units, and the units are assembled into units (reducer). They are installed on plumb lines lowered from horizontal strings. The roller bearings are mounted on the frames, aligning the marks on the bearing housings with the plumb lines, after which the distance between the axes and the deviation from parallelism are measured with a tape measure. Then a steel wedge with an angle of 3° is installed on the rollers, and a level is placed on it, and deviations of the angles of inclination of the rollers from the angle of inclination of the drum (3°) are measured and their position is adjusted by placing metal linings under the bearing housings. After adjusting the bearing housing is attached to the frame. The body of the dryer drum, together with temporary supports, is lifted with hydraulic jacks, wooden cages are removed and mounted on roller supports with bandages, and its position relative to the axis of rotation is measured and adjusted by shifting the roller bearing housings on the frames. Then install the end seals and the drive. The assembly of the drive begins with the installation of one of the halves of the ring gear on top of the plate packs, centering it relative to the axis of the drum body, after which it is bolted to the body. Then, with the help of winches and a crane, the drum body is rotated 180 ° and the second half of the gear is similarly installed and fastened and bolted together. After that, turning the body with winches through 90 ° for a full turn, the indicators measure and adjust the beating of the gear relative to the axis of rotation (it should not exceed 1 mm). The pinion gear is preliminarily installed on the foundation plate along the plumb lines, aligning the marks on the bearing housings with the plumb lines, the lateral (it should be no more than 0.5 mm) and radial (0.25 mm) clearances are measured, and they are adjusted by shifting the gear bearing housings. Then the bearing housings are temporarily fixed, several teeth are lubricated with paint and the drum is turned with a winch. Imprints remain on the surface of the teeth of the girth gear, by which they judge the correct engagement and fine-tune the position of the girth gear relative to the girth gear. The gearbox is pre-installed on the frame, its driven shaft is centered with the shaft of the girth gear by placing metal gaskets under the supporting surface and moving along the frame, after which the motor shaft is fixed and centered along the drive shaft. Drive guards, roller supports are installed, bearings, gearbox are filled with grease and the dryer drum is run in. When assembling the dryer drum, technological cards for assembling assembly units and the machine as a whole are used, specifications(TU) for assembly, car passport. The running-in of the dryer drum is done in order to run in its moving mating parts (rollers, drive), and the test is to determine the quality of its repair. Run-in and test modes are determined by the manufacturer. It is carried out by an experienced repairman (usually by the foreman of the repair team) and the driver serving him under the direct supervision of the repair manager. Before running in, the machine is carefully inspected, all its lubrication points are filled with grease, the electric motor is turned on, and the machine runs idle for 5-6 hours. Before starting, using a lever, turn the coupling connecting the electric motor to the gearbox and make sure that the drum turns easily and smoothly. During the run-in, they monitor the correct interaction of all parts and assemblies, the absence of noise, knocks and vibrations that are not characteristic of its normal operation, and the heating of the bearings (should not exceed 65 ° C). When they appear, the drum must be immediately stopped, the causes identified and eliminated. If troubleshooting is associated with the replacement of rubbing parts, then the break-in is repeated from the very beginning. Upon completion, the drum is inspected, grease is replaced at all lubrication points, and it is tested. To do this, the firebox is ignited, the smoke exhauster and the drum drive are turned on, and its internal parts are gradually heated to the operating temperature. At the end of the warm-up, the feeder is turned on and the material is fed for drying. The supply is dosed and stepwise: at first - by a quarter of productivity, then - by half, 3/4, and at the last stage - to the design one. At each stage, the dryer drum runs for 1.5-2 hours. If at the last stage the machine meets all the requirements (productivity, technological parameters of the dried material, power consumption, lubricants), the test ends and an act of the established form is drawn up, signed by the participants in the running and testing. During the test, all the work performed during the run-in is performed, and in addition:

1) using instruments, they monitor the temperature, the degree of discharge in various zones inside the housing and, if necessary, regulate them by changing the amount of fuel burned, air in the combustible mixture and covering or opening the smoke exhauster damper;

2) make sure that at each stage the material is fed evenly and foreign objects do not get into it.

4. Labor protection and fire protection

4.1 Basic safety rules for preparing and carrying out a major overhaul of the machine

The creation of safe working conditions for repairmen during the preparation and carrying out of a major overhaul of the machine is ensured by the implementation of the safety rules outlined below.

All workers must undergo a general safety briefing and, before performing each repair work (operation), directly at the workplace.

Before using repair equipment and portable power tools, they must be inspected and determined to be in good condition. When inspecting, it is necessary to pay special attention to the condition of the wire insulation, the presence and condition of grounding, fences, the reliability and serviceability of fasteners and their tightening. It is strictly forbidden to use faulty equipment and tools. Before starting work, it is necessary to check its operation "idle".

For disassembly and assembly of the dryer drum, a crane with a lifting capacity of 250 KN (pneumatic wheel) will be used. Persons who have completed training, passed exams and have a certificate for the right to operate are allowed to operate it. Hook parts, materials and other loads have the right to workers who have been trained and passed exams and have a slinger's certificate. Used pull and load-handling devices and containers must have a tag attached to them, which indicates the inventory number, date of testing, load capacity. Before use, they must be inspected and installed in good condition. It is forbidden to lift loads littered with something and loads, the weight of which is unknown, as well as to unscrew the bolts fastening the part or assemblies while under them.

Welders should work in a canvas suit and shoes, and to protect their eyes from an electric arc and a burner flame, they should use goggles and masks with light-protective glasses. Before starting work, check welding transformer and wires. They must have reliable insulation: individual pieces of wires must be connected with bolts and nuts installed in the terminal holes, and the connection point must be insulated. The ground wire to the workpiece must be connected with a quick-release threaded clamp. The place of welding should be fenced off with portable shields to protect those near those working from blinding by the welding arc. When welding and cutting metal and when performing other work inside the drum body, work must be performed by at least two workers, one of whom acts as an insurer. In addition, reliable ventilation inside the case must be provided, and dielectric rugs, galoshes and gloves must be used, and for lighting - portable lamps with a voltage of not more than 12 V. Gas welding equipment (torches, gearboxes, cylinders) must be inspected and established before use. On fittings, rubber hoses must be fastened with steel clamps, tightened with bolts and nuts. To connect the hoses to the reducer, and the reducer to the cylinders, you must use wrenches from non-ferrous alloys. Cylinders with gases must be transported on a specially equipped trolley and located no closer than 10 m from open flames and 5 m from closed heating devices. It is necessary to prevent the ingress of fuels and lubricants on the fittings of burners, gearboxes, cylinders and hoses, because. this can lead to an explosion when gases are supplied.

4.2 Basic rules for fire protection when overhauling a machine

Fire safety of maintenance personnel is ensured by strict observance and implementation of the measures and rules set out below. All workers involved in the repair must undergo a fire safety briefing before starting work. At the same time, they should indicate places that are dangerous in terms of fire, possible sources of fire (fuel, lubricants and detergents that can ignite from an electric arc, burner flame, splashes of molten metal and slag, insulation of electrical wires from short circuits). Everyone involved in the repair must know how and what to do in the event of a fire, how to leave the premises if necessary. The repair site must have fire extinguishing equipment (fire shield with equipment, sand in a steel box, tarpaulin cavities, water hoses and hydrants for their connection).

In the event of a fire, the source of ignition must be extinguished using water, sand and cavities, fire extinguishers. If the insulation of the electrical wires ignites, it is necessary to turn them off and only then extinguish them with dry sand, powder fire extinguishers and cover with a tarpaulin cavity. It is strictly forbidden to use foam fire extinguishers, water, and wet sand for this. If it is not possible to extinguish the fire, it is necessary to remove all people from the premises to a safe place and call the fire brigade.

4.3 Environmental protection when overhauling the machine

The main pollutants of the atmospheric air of the working area during the overhaul of the drying drum are gases released during cutting and welding of metals, and flue gases with dust during their removal. Therefore, the place of welding must be equipped with supply and exhaust ventilation, and the flue gases must be cleaned of dust in cyclones and electrostatic precipitators before being released into the atmosphere. Industrial water at the repair site may become contaminated from the ingress of fuels, lubricants and detergents. Therefore, it is necessary to store these materials in sealed containers in designated areas. It is strictly forbidden to drain their remains into the sewerage of the premises, and in case of spills, remove them using sawdust and rags. Rags, new and used, should be stored separately in metal closed boxes.

5. Special part

5.1 Scheme, device and operation of the machine

JSC "Krasnoselskstroymaterialy" uses a direct-flow drying drum for drying granulated slag. In which the direction of movement of the dried material (granulated slag) coincides with the direction of movement of flue gases inside the drum. The dryer drum consists of the following main parts (see Fig. 7.1):

Rice. 5.1 Scheme of the dryer drum: 1 - housing, 2 - bandage (2 pcs); 3 - transfer shelves, 4 - frame, 5 - roller support, 6 - dust chamber, 7 - seal; 8 - seal, 9 - thrust roller (2 pcs), 10 - ring gear, 11 - gear, 14 - casing, 15 - furnace, 16 - hopper. 17 - loading pipe, 18 - burner, 19 - branch pipe (2 pcs), 32 - gearbox, 33 - electric motor.

The body of the drum 1 is welded from separate shells made of sheet steel 09GS2. Inside, to increase heat transfer between the material and flue gases, steel gratings made of sheet steel are installed in its individual sections, and in the rest - bulk shelves 3 are welded to the body. When the material moves inside the case, its pieces are captured by the shelves 3. they rise to a certain height and fall off them, ending up in a stream of hot gases. Outside, two bandages 2 are put on the body, with which it rests on two roller supports. They are massive steel cylindrical rings, welded from two halves during the installation of the dryer drum. Between the inner surface of the bandages 2 and the outer casing, there are packs of steel plates welded to the casing, on which the bandages rest. In the cold state, there are gaps between the plate packs and the bandages, which turn into tightness during operation due to the heating and expansion of the drum body. The roller bearings consist (see drawing DPMA 02 01 00 00 00 80): of a pair of steel rollers pressed onto axles, the ends of which are fitted with spherical double-row ball bearings mounted in split steel housings. Bearing housings are mounted on frames 4 with guides, along which they can move with the help of screw adjustment devices 13, approaching each other or moving away, and are bolted to them. Thus, the position of the roller bearings is adjusted relative to the axis of the drum body. The drum 1 is set at an angle of 3° to the horizontal in order to ensure the movement of the material inside it. During operation, it can be displaced along the axis under the action of weight, therefore, to prevent the bandages from coming off the rollers of the idlers 5, two thrust rollers 9.11 are installed at the lower bandage, consisting of rollers installed in roller angular contact bearings put on the fixed axles. The upper part of the drum body 1 enters the opening in the wall of the furnace 15 for burning fuel, and the lower part enters the dust chamber 6. The dust chamber 6 has nozzles to which gas ducts are connected to remove gases from the body to dust precipitation plants to clean them from dust before ejection in atmosphere. To prevent outside air from entering the housing 1, seals 7 and 8 are installed at its ends. The drum rotates from a drive consisting of an electric motor 33, a gearbox 32, a crown gear 11 and a ring gear 10. The device and installation of the crown gear are similar to the roller bearing device. The bearing housings of the crown gear 11 are bolted to the fixed frame 4. The ring gear 10 consists of two halves, fastened with bolts. It is installed on packs of plates welded to the drum and fastened to them with bolts. From above, the crown 10 and the crown gears 9, 11 are covered with a casing 14 to protect against dust ingress and to ensure the safety of the operating personnel. The supply of material from the hopper 16 is carried out through the furnace, so the drying of the material begins as soon as it enters it. Fuel ( natural gas) is burned in the burner 18, where it is supplied together with air and, mixing, form a combustible mixture. The gases generated during the combustion of the combustible mixture from the burner enter the inside of the drum body 1, and, moving along it under the action of the expansion created by the smoke exhauster of the dust-collecting installation, they give off heat directly to the material, the walls of the drum body 1, the grate, the bulk shelves 3 (and those - to the material ), are cooled and discharged through pipes 19 to the dust collection unit. The dryer works as follows. The material (slag) loaded into the hopper 25 by a belt feeder continuously flows through the pipe 26 into the body of the drum 1, passes through it and through the pipes 19 of the dust chamber is unloaded onto the belt conveyor belt, which takes it away for further processing.

5.2 Calculation of the main parameters of the machine

Initial data:

1) outer diameter of the drum - Db = 2800 mm = 2.8 m; internal dB = 2760 mm = 2.76 m; drum length Lb = 20 m;

2) material to be dried - granulated slag with density ρ = 700 kg/m 3 ;

3) moisture content of the material - initial Wн = 22%, final Wк = 3%;

4) drum rotation frequency pb = 4.2 min 1. We make the calculation using (L - 1) - S. 163, 164.

5) inclination of the drum axis to the horizon, %; t = %.

Determine the drying time of a portion of the material:

where β is the fill factor of the drum body with material, β = 0.1...0.25; accept β = 0.2; A - steam removal, kg / (m 3 / h); A \u003d 45 ÷ 65 kg / (m 3 / h); accept A \u003d 55 kg / (m 3 / h);

We determine the performance of the dryer drum as a transport mechanism:

Pm = A0 × v ×Kz ×ρ

where A0 is the area of the inner section of the drum body, m 2 ;

v is the speed of movement of the material inside the drum along its axis, m/s;

Kz - coefficient of filling the volume of the drum with material; Kz = 0.1;

Pm \u003d 6 × 0.018 × 0.1 × 700 \u003d 7.56 kg / s \u003d 27.2 t / h

Determine the internal volume of the drum body:

Vob \u003d A0 × L \u003d 6 × 20 \u003d 120 m 2

We determine the performance of the dryer drum by the output of moisture:

Pw \u003d Pm \u003d [(14-2): (100-14) - 2: (100 - 2)] x 7.56 \u003d 0.9 kg / s

We determine the required volume of the drying drum as a drying unit:

The dimensions of the dryer drum ensure its operation as a thermal unit, since

5.3 Power calculation, motor selection and kinematic and force calculation of the drive

Determine the weight of the rotating parts of the dryer drum:

Gvr = Gb + Gm

where Gb is the weight of the drum assembly; Gb = 166 kN (factory data); Gm is the weight of the material in the drum body, KN;

Gm \u003d V b × K3 × ρ × g \u003d 120 × 0,l × 0.7 × 9.81 \u003d 82.4 KN;

Gvr = 166+ 82 = 248 kN.

5.3.1 Construction of a kinemic diagram

Fig.5.2. Kinematic scheme of the dryer drum

5.3.2 Kinematic and force calculation of the drive

We determine the power spent on lifting the material by the drum during drying according to the formula:

P1 \u003d 1.95 R 3 0b × L × ωb, kW

where ωb - angular speed of drum rotation, rad/s

R b - inner radius of the drum, m;

R0b \u003d D0b / 2 \u003d 2.76 / 2 \u003d 1.38 m

P1 \u003d 1.95 × 1.38 3 × 20 × 0.21 \u003d 21.5 kW.

We determine the power consumed to overcome friction in the rolling bearings of the support rollers:

P2 = 0.115 Gvr × r ×ωr, kW

Gtot - the weight of the rotational parts of the drum and material; Svr = 440 kN; r is the radius of rotation of the support rollers, m; r = 0.4 m; ωr - angular speed of rotation of the rollers, rad/s;

We determine the power expended to overcome the rolling friction of the tires on the rollers according to the formula:

Р3 = 0.0029Gvr × ωb = 0.0029 × 248 × 0.44 = 0.3 kW

We determine the required power of the electric motor by the formula:

where ŋpr - efficiency, taking into account power losses to overcome friction in the drive mechanism and in the drum seals; ŋpr \u003d 0.7 ... 0.8, we accept ŋpr -0.75.

According to the required power found, we select an engine of brand 4A 315510 UZ GOST 19523-81.

Table 1. Technical characteristics of the electric motor

Determine the gear ratio of the drive:

where Ured is the gear ratio of the gearbox; accept Ued \u003d 16

Uz.p. - gear ratio of the gear train

We determine the rotational speed, angular velocities, powers and torques on each shaft:

Р2 = Р1×ŋred, accept ŋred = 0.97; P2 \u003d 53.5 × 0.97 \u003d 51.9 kW

T2 \u003d P2 × 10 3 / ω2 \u003d 51.9 × 10 3 / 3.86 \u003d 13446 N.m.

On the drum

where ŋz.p. - gear transmission efficiency; ŋz.p. = 0.95.. .0.96; accept ŋz.p. = 0.95

The results of the calculations are entered in Fig. 5.2.

We select a standard cylindrical gearbox brand Ts2U-400N 16-12M-U3 TU2-056-165-77

Table. Technical characteristics of the gearbox

5.4 Calculation of gears for strength

5.4.1 Gear calculation

Initial data:

1) torque transmitted by the ring gear - Tz = 112057 N.m;

2) transmission ratio Uz.p. = 8.78;

3) continuous operation, with temporary overloads up to 20%

Design calculation

Since the gear is covered with a casing, we carry out the design calculation for the contact endurance of the teeth in the sequence recommended (3) - P. 35-46.

Determine the center distance of the transmission:

where Ka = 49.5 - for spur gears;

Кнβ - coefficient taking into account the uneven distribution of the load across the width of the crown; Knβ = 1... 1.15; accept Knβ = 1.15 according to GOST 2185-69;

ψva - gear rim width coefficient; ψva=v/A; accept ψva= 0.125;

[δ]n - allowable contact stress, MPa;

δHeimb - contact endurance limit at the base number of cycles;

KHL - durability factor; KHL = 1;

Safety factor; = 1.2.

We accept steel 45 for the manufacture of the crown gear

GOST 1050-88, having δT = 340 MPa, δv = 690 MPa, average hardness 200 HB, heat treatment is improved, and for the ring gear - steel 45L GOST 1050-88, δv = 520 MPa, δt = 290 MPa, average hardness - 180 HB, heat treatment - normalization ((3) - С.34, table. 3.3.). For the selected steels we find:

We accept aω = 2500 mm according to GOST 2185-76

We determine the module: m = (0.01..0.02) aω = 2500 × (0.01..0.02) = 25..50 mm;

we accept m = 25 mm according to GOST 2185-76.

Determine the number of teeth (total, ring gears)",

accept Z1 = 20; Z2 = ZΣ - Z1 = 200 - 20 = 180;

We specify the center distance:

aω = 0.5 ZΣ × m = 0.5 × 200 × 25 = 2500 mm - it has not changed;

Checking the gear ratio:

increase in Uz.p. is:

which is acceptable.

We calculate the parameters of the gear and ring gear:

1) pitch diameters - d1 (gears) = m × Z1 = 25 × 20 = 500 mm;

D2 (ring gear) = m × Z2 = 25 × 180 = 4500 mm;

2) outer diameters - da1 = d1+ 2m = 500 + 2 × 25 = 550 mm;

Da2 = d2 + 2m = 4500 + 2 × 25 = 4550 mm;

3) cavity diameter - df1 = d1 - 2.5m = 500 - 2.5 × 25 = 437.5 mm;

Df2 \u003d d2 - 2.5m \u003d 4500 - 2.5 × 25 \u003d 4437.5 mm;

4) width - b1 = b2 +15 mm = 315 +15 mm = 330 mm;

B2 = aω × ψva = 2500 × 0.125 = 312.5 mm; accept b2= 315 mm

We determine the forces in the meshing of the teeth:

1) district

2) radial Fr = Ft × tg 20° = 49.8 × 10 3 × 0.364 = 18.1 × 10 3 N; Determine the peripheral speed:

By vokr we assign the 8th degree of transmission accuracy b1=330MM

We determine the calculated contact stresses of the teeth:

where Zh is a coefficient that takes into account the shape of the mating surfaces of the teeth in the gearing pole; Zh = 1.76;

Zε - coefficient taking into account the total length of the contact lines; Zε= 0.9;

Kn - load factor; Kn = Knα × Knβ × Knγ × Knδ; (3) - S. 32;

Knα - coefficient taking into account the uneven distribution of the load between the teeth; Knα = 1.06; (3) - S. 39, tab. 3.4;

Knβ - coefficient taking into account the uneven distribution of the load across the width of the crown; depends on ψvd = b2 = 315 = 0.07; Knβ = 1; (3) - S. 39, tab. 3.5; d2 4500

Кнγ - dynamic coefficient, Кнγ= 1.05; (3) - S. 40, tab. 3.6;

We specify the allowable stresses on the contact endurance of the teeth:

where δHeimb 2 = 390 MPa; KHL = 1; = 1.2.

Zr is a coefficient that takes into account the influence of the roughness of the conjugated

surfaces; Zr= 0.9 - for the 8th degree of accuracy;

Zv is a coefficient that takes into account the influence of circumferential speed on the contact strength of the teeth; Zv = 1; (3) - S. 40.

Kl - coefficient taking into account the influence of the lubricant on the contact strength of the teeth; kl = 1;

Khn - coefficient taking into account the influence of the dimensions of the ring gear;

The contact strength of the teeth is ensured.

Verification calculation of gear teeth for bending endurance

Determine the allowable bending stress:

where δFeim - endurance limit at the equivalent number of cycles, MPa;

δFeim = δ°Feim×KFa×KFd×KFc×KFL; (3) - C.44

KFa - coefficient taking into account the influence of grinding of the transitional surface of the teeth; Kfa= 1;

KFd - coefficient taking into account the influence of strain hardening and electrochemical processing of the transition surface; KFd = 1;

KFc - coefficient taking into account the influence of the two-sided application of the load;

KFL - durability factor; KFL = 1;

δ°Feim - endurance limit at zero stress cycle, corresponding to their base number;

δ°Feim1 = 1.8 HB = 1.8 × 180 = 324 MPa - for the ring gear;

δ°Feim2 = 1.8 × 200 = 360 MPa - for gear;

δFeim2 = 324 × 1 × 1 × 1=324 MPa - for the ring gear;

δFeim1= 360 × 1 × 1 × 1= 360 MPa - for gear;

Ys - coefficient taking into account the stress gradient depending on the modulus; interpolating we get -

Yr - coefficient taking into account the roughness of the transitional surface; Yri = Yr2 =1;

KxF2 - coefficient taking into account the dimensions of the gear;

Safety factor; = [

" = 1.75; (3) - C.45, Table 3.9;

"2 - coefficient taking into account the effect on the bending endurance of the method of obtaining the workpiece;" =1.3 - for cast workpieces;

Let's define the ratio [δf]1/Y1 - for the pinion and [δf]2 /Y2 for the ring gear; where Y1 and Y 2 are coefficients that take into account the shape of the tooth; Y1 - 4.09; Y2=3.6;

The calculation of the teeth for bending is carried out according to the ring gear.

We determine the calculated bending stresses:

KF2 - load factor; KF2= KFβ × Kfv; (3) - C.42;

KFβ - coefficient of load distribution unevenness, depends on Xvo = b2/d2= =315/4500 = 0.07; KFβ=l.

Kfv - dynamic coefficient; Kfv = 1.25; Kf2 = 1 × 1.25 = 1.25.

The bending endurance of the teeth is ensured, since δf2 = 28.5 MPa< [δf]2 = 44,6 МПа.

5.5 Calculation of machine parts for strength

5.5.1 Calculation of the girth gear shaft

Initial data:

1) torque transmitted by the shaft - T \u003d T2 \u003d 13446 N.m \u003d 13446 × 10 3 N.mm;

2) angular velocity ω = ω2 = 3.86 rad/s;

3) circumferential force on the gear -Ft = 49.8 × 10 3 N;

4) radial force on the gear -Fr = 18.1 × 10 3 N;

Design calculation

We determine the diameter of the shaft end (under the coupling half) based on torsion only:

where Mk is the torque acting in the sections of the shaft end, N.mm;

Mk \u003d T \u003d 13446 × 10 3 N.mm;

[ĩ]k - permissible torsion stress, MPa (n / mm 2); [ĩ]k \u003d 20.. .30 n / mm 2;

we accept [ĩ]k \u003d 30 MPa (n / mm 2)

we accept according to GOST 6036-69 d = 150 mm.

Shaft verification calculation

We draw a diagram of the crown gear and assign the diameters of the shaft journals (see Fig. 5.4a): from left to right:

1) d1 = 150 mm - for fit of the coupling half;

2) dp = 170 mm - for bearing fit;

3) dsh \u003d 190 mm - for the landing of the girth gear.

We draw the design scheme of the shaft (Fig. 7.46). Mutually perpendicular circumferential Ft and radial Fv forces act on the gear. Let us replace their action on the shaft by the action of the resulting force:

Force Fres crosses the axis of the shaft at point "C" at a right angle. Let's turn the shaft so that Fres is directed vertically and draw a calculation scheme (see Fig. 7.4c). The shaft is acted upon by a flat system of forces Fres, bearing reactions Ra and Re. Since the force Fres is located at the same distance from bearings A and B, their reactions are directed, as shown in the diagram, and are equal to:

Ra \u003d Rb \u003d Fres / 2 \u003d 53 × 10 3 / 2 \u003d 26.5 × 10 3 N \u003d 26.5 KN.

We choose steel 45 GOST 1050-88 for the manufacture of the shaft, which has the following mechanical properties: tensile strength δv \u003d 890 MPa (n / mm 2), yield strength δt \u003d 650 MPa (n / mm 2), endurance limit for normal stresses δ-1 = 380

MPa (n / mm 2), endurance limit for shear stresses

ĩ -1 \u003d 0.58 × δ-1 \u003d 0.58 × 380 \u003d 220 MPa (n / mm 2),

average hardness - 285 HB, heat treatment - improvement.

We determine the bending moments in the shaft section:

Mia = Miv = Mib = 0; Mis \u003d Ra × 0.4 \u003d 26.5 × 10 g × 0.4 \u003d 10.6 × 10 3 N.m.

We build a diagram of bending moments (Fig. 5.4d).

Torque is transmitted from the middle of the half-coupling hub mounted on the extreme left shaft neck (see Fig. 5.4) to the middle of the ring gear in a clockwise direction (when viewed from the half-coupling side). Under its action, torques arise in the shaft sections in the BC section, which are the same in each section and equal to: Mk = T - 13446 N.m. We build a diagram of torques (Fig. 5.4d). As can be seen from the Mi and Mcr diagrams, the shaft section at point "C" with a diameter of d = 220 mm = 0.22 m is dangerous. We determine the stresses acting in it:

1) bending -

2) torsion -

Bending stresses change in a symmetrical cycle with an amplitude equal to: δa = δi = 10.0 MPa, (n/mm2). The torsion stresses change in a zero cycle with an amplitude equal to: ĩа = ĩк/2 = 6.3/2 = 3.15 MPa. In the shaft section "C" there are two stress concentrates: a keyway with a fillet and an interference fit. According to the note in (2) - S. 15, tab. 02, we take into account the stress concentration from the gear landing. For the dangerous section "C" of the shaft, we determine the coefficients that affect the stress concentration:

1) coefficient of influence of surface roughness - Kf = 1.2 (2) - p. 15, tab. 03;

2) coefficient of influence of surface hardening (without it) - Kv = 1.0; (2) - S. 15, tab. 04;

3) the ratio of effective stress concentration factors

4) concentration factor for dangerous section

We determine the endurance limits of the shaft in the dangerous section:

We determine the design safety factors of the shaft in the dangerous section according to normal and shear stresses:

We determine the overall design safety factor of the shaft in section "C":

The endurance of the shaft is ensured, since S > [S] = 2.5.

Rice. 5.4. Schemes for calculating the shaft

5.6 Selection and strength calculation of keys

5.6.1 Selection and calculation of the keyed connection "shaft-pinion"

Initial data:

1) shaft diameter d = dsh = 190 mm;

2) torque transmitted by keyway T = 13446 N.m = 13446 × 10 3 N.mm;

3) variable load, with temporary overloads by 20%

According to the shaft diameter d \u003d 190 mm, to connect the gear to it, we accept a prismatic key with rounded ends, having the following cross-sectional dimensions in accordance with GOST 23360-78:

1) width b = 45 mm;

2) height h = 25 mm;

3) groove depth t1 = 15 mm.

We accept steel 45 GOST 1050-88 for the manufacture of the key, which has permissible collapse stresses under variable load [δ] cm = 70 ... 100 N / mm 2; accept [<5]см = 80 Н/мм 2 . (2) - С. 77

The total length of the key is: ℓ = ℓp + b = 208 + 45 = 253 mm; we accept according to GOST 23360-78 I = 250 mm. We write down the key designation: 45x25x250 GOST 23360-78. The length of the gear hub is taken 10 mm more than the length of the key:

ℓst.sh. = 250+10 = 260mm.

5.6.2 Calculation of the shaft-coupling key connection

Initial data:

1) shaft diameter d = dp = 150 mm;

2) transmitted torque Т=13446 N.m;

3) variable load, with temporary overloads up to 20%.

We accept a parallel key with both rounded ends, having cross-sectional dimensions in accordance with GOST 23360-78:

1) width b = 36 mm;

2) height h = 20 mm;

3) groove depth t1= 12 mm.

Key material - steel 45 GOST 1050-88, allowable crushing stress [δ] cm = 80 N/mm 2 (see clause 7.6.1.).

Estimated key length is:

Since the length of the key is quite large, we accept two keys with a calculated length ℓp1 = ℓр/2= 165 mm.

The total length of each key is: ℓ = ℓr + b= 165+ 36 = 201 mm; we accept according to GOST 23360-78 I = 200 mm. Key designation: 36×20×200 GOST 23360-78. The length of the shaft neck will be determined by the length of the coupling half hub after its selection.

5.7 Selection and calculation of bearings

5.7.1 Selection and calculation of ring gear bearings

Initial data:

1) shaft angular velocity ω = ω2 = 3.86 rad/s;

2) shaft diameter d = dp = 170 mm;

3) radial reaction of the bearing Rr = Ra = 26.5 KN, axial - absent;

4) the load on the bearing is variable, with a temporary overload of 20%

Taking into account the working conditions, we plan to install a self-aligning radial spherical double-row roller bearing No. 1634 GOST 5720-75, having the following data: d = 170 mm; L = 360 mm, H = 120 mm, Sdin = 252 kN. Determine the equivalent dynamic radial load on the bearing:

Re = (XV × Rr + УRa) × Кδ × К ĩ ; (2)-S. 330.

where X, Y are the coefficients of radial and axial loads; x=1;

V is a coefficient that takes into account the dependence of the bearing durability on which of the rings rotates; V=1;

Kδ - safety factor, taking into account the influence of the nature of the loads on the durability of the bearing; Kδ \u003d 1.3 ... 1.8; accept Кδ = 1.6;

Kĩ - coefficient taking into account the influence of temperature on the durability of the bearing; Kĩ = 1. (2) - S. 331

Re = X × V × Rr × Kδ × Kĩ = l × 1 × 26.5 × 1.6 = 42.4 kN.

Determine the required design dynamic radial load rating of the bearing:

where p is the exponent; p -10/3; Lh is the required bearing life; Lh = 4000.. .30000 ; we accept Lh = 25000.

The durability of the selected bearing is ensured, since Schdin \u003d 141.4 KN< Счдин = 252 КН.

5.8 Selection and calculation of couplings

5.8.1 Selection and calculation of the coupling connecting the driven shaft of the gearbox with the shaft of the girth gear

Initial data:

1) shaft diameter d= dm =150 mm;

2) transmitted torque T = T2 = 13446 N.m;

3) working conditions - mode - continuous, loads - variable, with a temporary increase of up to 120%.

Given the large magnitude of the increasing moment and the operating conditions, we accept a gear coupling for installation. We determine the calculated torque for its selection:

Tr = K×T; (3)-S. 268;

where K is a coefficient that takes into account operating conditions; K \u003d 1.15 ... 1.2; accept K = 1.2; (3)-S. 272, tab. 11.3;

T \u003d 1.2 × 13446 \u003d 16135 N.m \u003d 16.135 KN.m

According to the shaft diameter d and Tr, we select a gear coupling and write down its symbol: coupling 23600-150-MZ-N GOST 5006-55. The selected coupling has the following parameters:

1) torque - 23600 N.m.;

2) bore hole diameter - d= 150 mm;

3) the length of the half-coupling hub - ℓ =210 mm;

j4) permissible speed [n] = 1900 min 1

5.8.2 Selection and calculation of the coupling connecting the shafts of the electric motor and gearbox

Initial data:

1) shaft diameter d = 75 mm, neck length ℓ = 140 mm;

2) transmitted torque Т=Т1 = 866 N.m;

3) working conditions - variable loads with a short-term increase of up to 120%.

We accept an elastic sleeve-finger coupling (MUVP) for installation. Estimated moment for choosing a coupling half - Tr \u003d K × T \u003d 1.2 × 866 \u003d 1040 N.m. We select the coupling and write down its designation: MUVP 2000-75-11.-UZ GOST 21424-75. The coupling has parameters:

1) rated torque - 2000 N.m;

2) bore diameter – d= 75 mm, length -ℓ = 140 mm;

3) the landing hole is cylindrical;

4) outer diameter - 250 mm, type I, execution 1.

5.9 Rules for the technical operation of the machine and safety precautions for its maintenance

5.9.1 Rules for technical operation

The tumble dryer operates in continuous automatic mode. Its long and safe operation is ensured by proper operation, subject to the following rules. When accepting and handing over a shift, the maintenance personnel must inspect all its components and parts and identify their technical condition. When examining, pay attention to:

1) the condition and reliability of the attachment points of the electric motor, gearbox, bearing housings, girth and girth gears, idlers;

2) the degree of wear and the presence of cracks and breakages in the teeth of the crown and girth gears, the drum housing, bandages, rollers;

3) the presence and quality of lubrication of the gear, bearings and gearbox, the absence of its leakage.

While the tumble dryer is in operation:

– Monitor the uniformity of the material supply, as uneven supply reduces its productivity.

– Make sure that foreign objects do not get inside the drum along with the material, as this may lead to an accident.

- Using instruments, monitor the temperature in various zones of the drum and correct it by increasing or decreasing the supply of combustible mixture to the burners, as well as changing its composition (air-to-fuel ratio). In addition, the temperature value is affected by the degree of vacuum inside the drum, which determines the speed of movement of gases in the drum and their heat transfer (it increases with a decrease in speed).

- Periodically, by taking control samples and analyzing them, determine the moisture content of the material at the outlet of the drum and, if it deviates beyond the permissible limits, correct it by changing the fuel supply, its composition and vacuum inside the drum.

– Monitor the heating of roller bearings, girth gear, reducer. Heating up to 65°C is allowed.

– If there are knocks and noises that are not characteristic of the normal operation of the tumble dryer, it must be stopped immediately, the cause identified and eliminated. Stop the tumble dryer only in emergency situations and for repairs and maintenance. To do this, the feeder is stopped, all the material in the drum is exhausted, the fuel supply to the burners is stopped, and without stopping the drive motor and smoke exhauster, the drum body is cooled to 40°C, after which it is turned off. Stopping the heated drum is allowed for no more than 15 minutes. A longer stop may cause hull deflection. Starting the dryer drum after repair takes several hours, because its body must first be warmed up at idle to the workers. Temperatures, after which the supply of material starts from the minimum and increases to the nominal in accordance with the mode set by the manufacturer. Before starting, the drum is carefully inspected, and all detected faults are eliminated.

5.9.2 Personal safety regulations

The safety of personnel operating the tumble dryer is ensured by following and observing the following rules:

– The control system of the dryer must have an electrical interlock that ensures the following starting order: smoke exhauster - belt discharge conveyor - dryer drum - belt feeder, and when stopped, the reverse order of shutdown. In addition, when the discharge in the furnace for fuel combustion falls below the permissible level, the fuel supply to the burner must be stopped. Cleaning, washing of the drum is carried out only when it stops, using crowbars, metal brushes, shovels, scrapers, hoses with compressed air and water, rags, kerosene, diesel fuel.

- Support and thrust rollers, girth and girth gears must be protected by solid metal fences (casings), and gas passages

– heat insulated to prevent the possibility of burns for service personnel.

- To prevent the start of the dryer drum, it must be equipped with light and sound alarms (flashing red electric lamps and an electric bell), which must ensure the visibility and audibility of the signals for all those working in the drying department.

– The seals of the tumble dryer body and the degree of vacuum inside it, as well as the tightness of the loading and unloading devices, must prevent the penetration of flue gases into the working room. When the vacuum in the dust chamber of the drying drum falls below the norm, the automation should turn off the fuel supply to the burner. The degree of gas contamination of the working room of the drying department must be constantly monitored by sampling and express analysis of air samples. If the gas content exceeds sanitary standards, the operation of the dryer drum should be prohibited. Dust collecting installations of drying units must ensure the purification of gases and air from dust before being released into the atmosphere not below sanitary standards.

- To protect the operating personnel from electric shock, the body of the electrical panels, the electric motor of the dryer drum must have grounding devices connected to the workshop ground loop.

– The tumble dryer must be serviced by persons who have undergone training, training and safety briefing, who have passed the qualification exam.

– When inspecting the dryer drum, it is necessary to assess the technical condition and reliability of fastening of all fences and grounding devices. All detected faults must be corrected. Work with faulty fences and grounding is strictly prohibited.

– Do not lubricate, troubleshoot or repair while the drive is running. To do this, you need to stop the drum, turn off its electric motor with the removal of fuses, posters are posted on the starting devices with the inscription "Do not turn on - people are working!"

- Internal inspection and repair of the hull must be carried out by at least two workers, one of whom acts as an insurer, according to the permit. For lighting, portable lamps in a closed version with a voltage of not more than 12 V should be used.

– During ignition and operation of the drying drum, it is forbidden to open the doors of the furnaces, stand in front of them, observe the combustion of fuel without goggles with tinted glasses, and stay under its body during operation.

5.10 Machine lubrication map and diagram

The dryer drum lubrication chart is designed by the manufacturer and is a simplified diagram showing the position of all its lubrication points. The lubrication points on the diagram are numbered.

Rice. 5.5. Tumble dryer lubrication diagram

The lubrication map is a table containing the names of lubrication points, the modes and methods of lubrication of each of them, indicating the lubricant used.

Table 3. Tumble dryer lubrication map

Lubrication point name	Lubricant	Lubrication method	Periodicity, months
Lubrication point name	Lubricant	Lubrication method	adding lubricant	Lubricant changes
Support roller bearings
Thrust roller bearings	grease US-2 GOST 4366-76	Manual cap	as it develops
reducer	Industrial oil I-50A GOST 20799-75	crankcase
gear clutch	grease US-2 GOST 4366-76	injection
ring and girth gears	Autotractor oil AK-15 GOST 10541-78	crankcase
Pinion gear bearings	Industrial oil I-50A GOST 20799-75	centralized under pressure

6. Economic part

The economic part of the diploma project aims to determine the feasibility study for the overhaul of the drying drum. To determine the technical and economic indicators of the overhaul of the drying drum, it is necessary to calculate:

- material costs for the overhaul of the dryer drum;

- wages of workers;

- an estimate of the cost of overhauling the dryer drum.

6.1 Calculation of the cost of material costs for the overhaul of the dryer drum

The cost of material costs is determined based on the specific consumption rates of materials for components and parts and list prices.

Table 6.1. The cost of material costs.

Name of materials and components	Units	Specific consumption rate	Need, total	Unit of measurement thousand roubles.	Amount thousand rubles
Drum St09G2S
Bandage STZOGSL
Support roller St35
Thrust roller St35
Girth gear St40X
Drive shaft St40X
Roller frame STZ
Roller axle St45
Girth gear shaft St45

Unaccounted materials - 10% of the accounted

Electric motor 55kW
Reducer Ts2U-400N
Bearing 1634
gear clutch


Unaccounted components - 10% of the accounted

6.2 Calculation of labor costs for the overhaul of the dryer drum

The calculation of labor costs is determined by the complexity of the overhaul of equipment. The total standard labor intensity of one overhaul of the dryer drum is 800 man-hours.

6.2.1 Payroll calculation of workers

The wages of workers are determined on the basis of the complexity of the overhaul of the dryer drum and the hourly wage rate of a worker of the IV category with normal working conditions.

Table 6.2. Workers' wages.

Supplement to wages according to the tariff for the performance of the task - 70% of the tariff rate (Regulations on bonuses):

Zvyp \u003d 3 tare × 0.7, thousand rub.

Zvyp \u003d 1968 × 0.7 \u003d 1377.6 thousand rubles.

Payment at night 5% of the tariff rate:

Znoch = 3 tare × 0.05, thousand rubles

3 nights \u003d 1968 × 0.05 \u003d 98.4 thousand rubles.

The basic payroll is:

Zosn \u003d Ztar + Zvyp + Znoch, THOUSAND. rub.

3 0CH \u003d 1968 + 1377.6 + 98.4 \u003d 3444 thousand rubles.

Additional salary - 12% of the basic salary fund:

Zdop \u003d Zosn × 0.12, thousand rubles

Zdop \u003d 3444 × 0.12 \u003d 413.28 thousand rubles.

The total payroll will be:

3 0bsch \u003d 3bas + Zdop, THOUSAND. rub.

3 0bshch \u003d 3444 + 413.28 \u003d 3857.28 thousand rubles.

6.2.2 Calculation of the cost estimate for the overhaul of the tumble dryer

Costs include the following taxes and fees:

1.Deductions for social insurance - 35% of the total wage fund:

Sotch \u003d 3 0bsch × 0.35, thousand rubles

With otch \u003d 3857.28 × 0.35 \u003d 1350 thousand rubles.

2. emergency tax - 3% of the total payroll fund:

H h \u003d 3 0bshch × 0.03, thousand rubles

H h \u003d 3857.28 × 0.03 \u003d 115.72 thousand rubles.

3. contributions to the employment fund - 1% of the total wage fund:

Nf \u003d 3 0bshch × 0.01, thousand rubles

Nf \u003d 3857.28 × 0.01 \u003d 38.57 thousand rubles.

General production expenses (120-150% of the basic salary):

P p \u003d Zosn × (1.2-1.5), thousand rub.

P p \u003d 3444 × 1.2 \u003d 4132.8 thousand rubles.

General business expenses (150-230% of the basic salary):

O p = Zosn × (1.5-2.3), thousand rubles

About p \u003d 3444 × 1.5 \u003d 5166 thousand rubles.

The cost estimate for the overhaul of the dryer drum is compiled in the following form:

Table 6.3. Cost estimate

Expenditures	Notation	Amount thousand rubles
1. Materials
2. Accessories
3. Basic salary
4. Additional salary
5.Deduction for social insurance
6. Extraordinary tax
7. Contributions to the employment fund
8. General production costs
9.General expenses

I believe that the overhaul of the drying drum, carried out by the enterprise's repair and mechanical workshop, is expedient, since the purchase, the cost of a new drying drum, will cost the enterprise 70,664 thousand rubles.

Having carried out a major overhaul of the dryer drum on its own, the enterprise saves 31,798.6344 thousand rubles.

Literature

1. Loskutov Yu.A et al. Mechanical equipment of enterprises for the production of binder building materials. - M .: "Engineering", 1986.

2. Ilyevich A.P. Machinery and equipment for factories for the production of ceramics and refractories. M. Higher School, 1979.

3. Chernavsky S.A. Course design of machine parts. M. Engineering, 1987.

4. Kuklin N.T., Kuklina G.S. Machine parts. M. Higher School, 1987.

5. Banit F.G. and other Operation, repair and installation of equipment for the building materials industry. M. Stroyizdat, 1971.

6. Drozdov N.E. Operation, repair and testing of equipment of building materials, products and structures. M. Higher School, 1979.

7. Makhnovich A. T., Bokhanko G.I. Occupational safety and fire protection at enterprises of the building materials industry. M. Stroyizdat, 1978.

8. Samoilov M.V. etc. Fundamentals of energy saving. Mn. BSEU, 2002.

9. Sapozhnikov M.Ya., Drozdov N.E. Reference book on the equipment of factories of building materials. Stroyizdat, 1970.

10.Sokolovsky L.V. Energy saving in construction. Mn. NP OOO Strinko, 2000.

Machinery and apparatus for chemical production arouse genuine interest on the part of workers in the sphere and ordinary people. Given that the chemical industry is quite specific, the equipment involved in production is also unique.

Gear ratio

Rated torque on driven shaft

Shaft journal dimensions

Ts2U-400N-16-12M--UZTU2-056-165-77

Chemical equipment is needed for thermodynamic and hydromechanical processes.

Hydromechanical - the simplest processes in the chemical industry. Devices for them work on the principle of separation: they divide heterogeneous mixtures and liquids, clean them from solid particles. The meaning of this process is to purify gases from pollution. In this case, a precipitating-filtering centrifuge is used. The machine first filters the liquid or gas, and the filter separates the solid particles. Then precipitation occurs. This process is rather slow because the force of gravity acting on small particles is small.

The stirrer performs mixing of the particles. An installation for the preparation of emulsions and suspensions is needed to first grind any reagent, and then convert it into a mixture with the desired concentration.

The process of moving flows in chemical apparatuses is performed by a chemical pump. It works with aggressive liquids in highly toxic environments. The compressor machine is irreplaceable in production. It cools and compresses gases.

How are thermodynamic processes in the chemical sector of production and what devices are used.

Thermal chemical processes take place in packed absorbers. Absorbers are film, bubbling, packed, spraying. Absorption is the process of absorption of gas mixtures by liquid absorbers.

Apparatus for treated osmosis. This is a membrane separation process, which is based on the penetration of a diffuse substance through the membrane. To machines and devices of chemical production refers to the device of cyclic reflection. He is engaged in the separation of liquid substances through distillation.

Installation for extraction. Extraction is the extraction of bodies from solutions using an extractant. Dryers remove moisture by diffusion and evaporation.

This is just a small list of devices and machines involved in chemical production. Naturally, production is developing, introducing new technologies for the processing of substances.

The international exhibition "Chemistry" will take place in autumn. The organizer of the exhibition this time was the Central Exhibition Complex "Expocentre". A major industry exhibition is celebrating its anniversary. And this means that the event will be special. International and domestic delegates and exhibitors will present innovative achievements in chemical production, introduce visitors to the discoveries of the chemical industry. Prospects for development, market trends, the latest achievements of analytical and laboratory equipment capable of ensuring the functioning of any modern laboratory will be presented.

Particular attention will be paid to chemicals and raw materials. The testing equipment will be certified. Almost all equipment will be demonstrated.

This event attracts scientists, executive power and ordinary visitors. Exhibition subject:

laboratory design;

safe production;

biotechnologies in medical, textile, food industry;

advances in the chemical industry.

An extensive business program will be carried out within the framework of the project. Round table, seminars and conferences - all this will be held at the "Chemistry" exposition.

The exhibition will raise questions:

competent management of technical production;

design of warehouses and terminals;

scientific research and technology.

All this will make it possible to hold an event that will interest not only those who are involved in the industry or are interested in chemical production, but also ordinary residents. The exhibition will make it possible to find new partners and strengthen existing business relations. The main role in this is played by the favorable location of the complex: good road junction, close metro stations, the presence of a business center nearby.

Read our other articles:

The methodological guidelines were reviewed and approved at a meeting of the subject (cyclic) commission of the mining cycle disciplines and special disciplines for mineral processing

Minutes No. _____ dated "_____" __________________ 20____

Chairman _________________ V. P. Novikova

Introduction…………………………………………………………………………...
1 General requirements for the completion of the graduation project……………………...
1.1 General rules for the implementation of the graduation project…………………...
1.2 Design of the graphic part of the graduation project…………………..
1.3 General requirements for the design and construction of an explanatory note……………………………………………………………...
1.4 Requirements for the design of the list of contents of a text document……………………………………………………………..
1.5 The procedure for compiling a list of sources used……………...
2 Topics of graduation projects…………………………………………………...
3 Approximate content of the explanatory note……………………………...
3.1 Reconstruction of existing branches………………………………….
3.2 Overhaul of the machine (device)………………………………...
3.3 Mechanization of labor-intensive processes……………………………………...
3.4 General guidelines for calculating the economic part of the graduation project……………………………………………………………….
4 Pre-graduation internship………………………………….
5 Defense of the graduation project………………………………………………………
List of used sources…………………………………………….
Annex A Assignment for the graduation project……………………………….

Introduction

The diploma project is a large independent work of the future mechanical engineer of chemical production, aimed at solving specific problems in the field of improving the operation of process equipment, organizing repair production and improving the technical and economic indicators of the site or workshop.

The main purpose of the manual is to familiarize students with the topic of graduation project and the nature of the requirements for the graduation project, which will help the student to bring regularity to the work on the project and will stimulate a creative approach to developing the theme of the graduation project with the maximum manifestation of initiative within the framework of clearly defined general requirements for content. and the volume of all sections of the graduation project, as well as the design of the explanatory note and the graphic part of the project in accordance with the ESKD standards.

The work on the project should be based on the specific material of the enterprise where the undergraduate practice is carried out or where the student works, and the project topic itself should be relevant, meet the modern requirements of science and technology, take into account the real tasks of the industry in increasing production efficiency. The diploma project is the final work of the student, on the basis of which the State Qualification Commission decides whether to award him the qualification of a mechanical technician.

1 General requirements for the implementation and design of the graduation project

General rules for the implementation of the graduation project

The diploma project consists of two parts: an explanatory note and a graphic part. The main part of the graduation project is the graphic part. The settlement and explanatory note expands and explains the graphic part of the graduation project, so both parts of the graduation project form a single whole.

The graphic part of the diploma project is presented in the form of technological drawings, power supply schemes of the complex, diagrams, tables of economic indicators, etc.

The required number and composition of graphic materials in each case are determined by the project manager together with the student. The graduation project must contain at least 4 drawings.

The general requirements for the explanatory note of the graduation project are: clarity and logical sequence of presentation of the material, specificity of the results of calculations, evidence and conclusions, brevity and clarity of wording that excludes ambiguity of interpretation.

The calculation and explanatory note of the graduation project should briefly and clearly disclose the creative idea, contain the accepted calculation methods, the efficiency of the use of electrical equipment and the rationality of its use. If necessary, calculations should be accompanied by illustrations: graphs, sketches, diagrams, diagrams, etc. The volume of the explanatory note should be approximately no more than 80 pages.

Registration of the graphic part of the graduation project

Any type of design documentation is framed and in accordance with GOST 2.106-96 and the main inscription in accordance with GOST 2.104-2006 located in the lower right corner. On formats A4(294*210) the main inscriptions are located only along the short side of the sheet.

Frames and main inscriptions are made with solid main and solid thin lines along GOST 2.303.

The main inscription for the explanatory note is made according to GOST 2.104-2006(Form 2) for the title page in accordance with Figure 1, for subsequent pages - (Form 2a) in accordance with Figure 2.

Picture 1

Figure 2

For drawings and diagrams, the main inscription is made according to GOST 2.104-2006 for the first sheet (form 1) in accordance with figure 3, for the subsequent ones - (form 2a) in accordance with figure 2.

Figure 3

In the columns of the main inscription (numbers of the columns on the forms are shown in brackets) indicate:

Column 1- product name (in the nominative singular without transferring part of the words to another line). Fill in the column, in lower case letters GOST 2.304-81(font number of choice, depending on the number of words in the title). For example, "Frame". In names consisting of several words, there should be a direct word order, for example "Toothed wheel".

Column 2 - document designation GOST 2.201-80.

The designation is accepted according to the enterprise standard, i.e. this educational institution.

For the specialty 2-36 07 01 "Machines and apparatus for chemical production and building materials enterprises", the simplified alphanumeric designation consists of five groups:

XX	XX	XX	XX	XX	XX
1 gr.	2 gr.	3 gr.	4 gr.	5 gr.	6 gr.
	00 00 00

First group - an individual code of the student according to the educational journal.

Second group – specialty code (six digits).

Third group - designation of the unit of the product (document).

Fourth group - designation of the subassembly of the product.

Fifth group

Sixth group - document cipher.

For example:

In the explanatory note:

36 07 01 – specialty code MA;

00. 00. 000 – designation of the node (document);

PZ- explanatory note (document code)

On the graphic part:

- for the assembly drawing:

01 - student's individual code according to the journal;

36 07 01 – specialty code MA;

00 - designation of the unit of the product (document);

000 - part number of the assembly drawing;

Sat– assembly drawing ;

IN– general view drawing;

According to GOST 21.101-93 SPDS (construction documentation design system).

TX- production technology.

- for drawings of parts of an assembly drawing:

01.36 07 01. 00. 00. 001

01 - student's individual code according to the journal;

36 07 01 – specialty code MA;

00 – designation of the unit of the product (document);

00 - designation of the subassembly of the product;

001 - part number of the assembly drawing.

Column 3- designation of the material of the part (the column is filled out only on the working drawings) font number 5, for example: Steel 45 GOST 1050-88.

Column 4- the letter assigned to this document.

According to the developed STP1-08 introduce document designations.

UDP– educational diploma project;

UDR - academic thesis;

UKP - educational course project;

UPR - training practice record;

UKR - academic course work;

DKR - home control work.

Column 5- the mass of the product.

Column 6- scale (set in accordance with GOST 2.302-68 and GOST2.109-73 font number 5).

Column 7- serial number of the sheet.

Column 8- the total number of sheets of the document (the column is filled out only on the first sheet).

Column 9- distinctive index of the educational institution and group,

Font number 5

For example: SGGCC MA-1-05

Column 10- the nature of the work performed by the person signing the document. For study papers, write:

Developed (Developed)

Checked (Checked)

Norm control (N. counter.)

Box 11- the names of the persons signing the document.

Box 12- signatures of persons whose names are indicated in column 11.

Box 13- date of signing the document.

Columns 14-18- do not fill.

1.3 General requirements for the design and construction of an explanatory note

Text documents are executed on forms established by the relevant standards of the Unified Design Documentation System (ESKD) and the Design Documentation System for Construction (SPDS).

Text is done in one of the following ways:

handwritten - in black on one side of the sheet.

typewritten - in a clear black font with a lowercase letter height of at least 2.5mm, capital letter height - 3.5mm, according to GOST 2.304-68;

With the use of printing and graphic output devices of a computer ( GOST 2.004) - font Times New Roman Cyr black color font 14. Line spacing should be Word 97-03 − accurate 18 points Word 07- 1,15 .

The print font must be straight, light, clear, black, the same throughout the document.

It is allowed to use computer capabilities of focusing attention on definitions, terms, important features, using different font styles: italic, bold, italic bold, highlighting with frames, spacing, underlining, and more.

To enter into text documents made in a typewritten way, individual words, formulas, conventional signs (handwritten), as well as illustrations should be done in black ink, paste or ink. Each sheet of a text document must have a frame. The frame is made in black by typography or by hand with black ink. The frame is made with a solid main line at a distance 20 mm from the left border of the format, 5 mm from the rest of the format boundaries.

The distance from the format frame to the text boundaries at the beginning and at the end of lines is not less than 3 mm.

The distance from the top or bottom line of text to the top or bottom frame must be at least 10 mm.

Paragraphs in the text start with an indent (15-17 mm).

Misprints, misprints and graphical inaccuracies discovered during the execution of the document may be corrected by erasing or painting over with white paint and applying the corrected text (graphics) in the same place in typewritten way or in black ink, paste or handwritten ink.

Statement of the text of the document

The text of the document, if necessary, is divided into sections and subsections.

Sheets of the document are numbered, starting with the sheet with the title block. GOST 2.104-2006. The numbering of pages of the document and annexes included in this document must be continuous.

Sections should have sequential numbers within the entire document, indicated by Arabic numerals without a dot and written with a paragraph indent.

Subsections should be numbered within each section. The subsection number consists of the section and subsection numbers separated by a dot. Dots are not put at the end of the subsection number. Sections, like subsections, can consist of one or more paragraphs.

Each paragraph, subparagraph and enumeration is written from a paragraph.

Sections and subsections should have headings. Items usually do not have headings. Headings should be printed with a capital letter without a dot at the end, without underlining (for sections, font No. 7 according to GOST 2.304; font 28 according to GOST 2.004, bold), (for subsections, font No. 5 according to GOST 2.304; font 24 according to GOST 2.004, bold) . Word hyphenation in headings is not allowed. If the heading consists of two sentences, they are separated by a dot.

The distance between the heading and the text when executing the document in typewritten way should be equal to 3.4 intervals, when executing in handwriting - 15 mm. The distance between the headings of the section and subsection is 2 intervals, when done in handwriting - 8 mm.

Abbreviations of words in the text and captions under illustrations, except for the generally accepted abbreviations established by GOST 2. 316, are not allowed.

In formulas, the symbols established by the relevant standards should be used as symbols.

If the document contains more than one formula, then they are numbered in Arabic numerals within sections or through numbering, the number is placed on the right side of the sheet at the level of the formula in parentheses.

The meaning of the symbols and numerical coefficients included in the formula must be given directly below the formula. The value of each character from a new line is given in the order in which they are given in the formula.

The first line of the decryption must begin with the words "where", without a colon after it, for example:

(1)

where Q E– operational productivity, t/h;

Q T– technical productivity, t/h;

k and- coefficient of use of the machine in time;

t SM- duration of the shift, h.

The distance between the text and the formula should be equal to 2 intervals, when done in handwriting - 10 mm.

Design of illustrations and applications

The number of illustrations should be sufficient to explain the text presented. Illustrations can be located both in the text of the document and at the end of it. Illustrations must be made in accordance with the requirements of ESKD and SPDS standards. Illustrations, with the exception of illustrations of appendices, should be numbered consecutively.

The illustrations of each application are designated by a separate numbering in Arabic numerals with the addition of the application designation before the number. For example - Figure A.3.

It is allowed to number illustrations within the section. In this case, the illustration number consists of the section number and the number of the illustration separated by a dot. For example - Figure 1.1.

Illustrations, if necessary, may have a name and explanatory data (figure text).

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Machinery and apparatus for chemical production

Lecture course

1. Classification of chemical machines and apparatuses. 2

2. Apparatus for mixing liquid media. 2

3. Device designs. 4

4. Mechanical mixing devices. 5

5. Method for calculating mixing devices. thirteen

6. Agitator drives. nineteen

7. Seals. 29

8. Filters. Classification of heterogeneous systems. 42

9. Filters for separation of suspensions. 42

10. Classification of filters. 44

11. Typical designs. 44

12. Centrifuges. 56

13. Classification of centrifuges. 57

14. Methods for unloading sediment from centrifuge rotors. 59

15. Designs of centrifuges. 67

16. Method of calculation. 74

17. Basic provisions for calculating the strength of centrifuge rotors. 82

18. Critical shaft speed. 86

19. Pipeline systems. Classification of technological pipeline systems 90

20. Shut-off valves. 94

21. Cranes.. 95

22. Valves. 101

23. Gate valves. 106

24. Chemical industry reactors. 109

25. Classification of chemical reactions. 110

26. Classification of reactors. 110

27. Apparatuses of ideal displacement, ideal mixing and intermediate type 112

28. Reactors for conducting homogeneous reactions in the gas phase. 114

29. Reactors for the liquid-liquid system. 117

30. Worm machines. Purpose and classification. 120

31. The scheme of the worm machine .. 120

32. Theoretical foundations of material processing in non-worm machines. 122

33. Roll machines.. 127

34. Design of roller machines. 128

35. Main parts and components of roll machines. 131

Basic concepts and definitions

A machine is a device for processing material, moreover, the material can change its shape, dimensions, but does not change its chemical composition.

Apparatus - a device for processing material is called, while the material changes its physical and mechanical properties.

Classification of chemical machines and apparatuses

Classification is a logical operation that consists in dividing a set of objects into separate groups according to the detected similarities. The classification of machines and apparatus is carried out to streamline the nomenclatures and specialization of chemical engineering plants. An example is the enlarged classification of chemical equipment, which includes 20 groups. At the same time, 15 groups of equipment for the chemical process were identified:

1. Apparatuses of capacitive type with mixing devices

2. Capacitive type devices with fixed devices

3. Filters

4. Centrifuges

5. Liquid separators

6. Crystallizers

7. Granulators

8. Heat exchangers

9. Evaporators

10. Column devices

11. Dryers

12. Apparatus with rotating drums for roasting, drying and crystallization

13. Electrolyzers

14. Paint-cutting machines

15 Industrial ovens

Three groups according to the specific qualities of the equipment itself:

1. High pressure apparatus (R.> 64 kg / cm 2)

2. Enamel hardware

3. Devices made of non-metallic materials

Apparatus designs

The choice of apparatus with mixing devices and the design features of the apparatus are determined by the characteristics of the process, the properties of the medium being mixed, the productivity of the technological line, the temperature parameters of the process and the pressure at which the process is carried out. Such a variety of factors influencing the choice of design complicates the task of optimal design of devices.

The main processes of chemical technology, for which apparatuses with stirrers are used, are usually carried out in a liquid inhomogeneous medium. A liquid inhomogeneous medium is understood as a single or multicomponent medium with an uneven concentration or temperature, as well as a liquid inhomogeneous system consisting of a dispersed phase distributed in a liquid medium.

In practice, the most widely used mechanical method of mixing liquid media, carried out by mechanical action of the working body (mixer) on the working environment.

This mixing method is used in an apparatus, which usually consists of a housing, a mixing device and its drive.

The most important in the operation of the apparatus is the type and design of the stirred device, the operation of which is to convert the ordered mechanical energy of rotating elements into disordered thermal energy due to the resistance forces created by the apparatus body. As a result, the mixing device dissipates energy in the volume of the apparatus, the value of which depends both on the design of the mixer and the characteristics of the drive, and on the design of the apparatus and its internal devices. All these characteristics of the apparatus together determine the mixing power N. The volumetric power, which characterizes the dissipation in the apparatus, can also serve as a measure of the mixing power:

Where V- the volume of the stirred liquid, equal to the volume of the apparatus V at the filling factor of the apparatus j = 1.0 (in this case, the coefficient j is understood as the ratio V W /V).

In an apparatus of any volume, depending on the rotation frequency n, there are various hydrodynamic modes of fluid movement that determine the value of E. The areas of operation of the apparatus can therefore be characterized by a measure of this value - the power criterion K n, which is determined by the formula:

, (1.2)

where r is the density of the stirred medium, ; d - mixer diameter, m, n - number of revolutions of the mixer, c -1.

For devices of all types, the value of K n is determined, first of all, by the Reynolds centrifugal criterion Re c, since:

, (1.3)

Wherein:

, (1.4)

Where m is the dynamic viscosity coefficient.

Dependence (1.3) characterizes the most general patterns of fluid motion in the apparatus.

Agitator drives

Slow-speed agitators - paddle, anchor, etc. - are usually driven by an individual electric motor through a gear train.

The drives are usually mounted on the covers of the apparatus in which the agitator operates, sometimes on beams or frames mounted on the roof. If the shaft is long, then an additional support is mounted on the bottom of the vessel. In modern designs, the drive is usually carried out directly from the electric motor, through a gearbox.

For combined agitators, drives of the type shown in Figure 14 are used.

Figure 14 - Combined mixer drive.

From shaft 1, rotation is transmitted through two bevel gears: through wheels 3 and 5 in one direction and through wheels 2 and 4 in reverse direction. If the gear ratios of both pairs are the same, then the shafts of wheels 4 and 5 will rotate at the same speed, but in different directions.

If the combined agitator consists of a low-speed and a high-speed agitator, two independent drives are installed. The anchor agitator is driven by an electric motor through a pair of conical wheels, and the turbine agitator is driven by its own electric motor (the shafts are connected by couplings).

If there is not enough space on or above the vessel lid, the actuator is placed under the vessel, which however requires a good gland seal.

Drives for propeller agitators are most often carried out depending on the rotation speed: 1. from an electric motor directly connected to the agitator shaft; 2. from the electric motor through the gear transmission; 3. from the electric motor with the built-in reducer; 4. from the electric motor through a V-belt transmission.

An example of a drive of the first type for stationary propellers is shown in Figure 15.

Variable speed electric motors are also used, which makes the agitator more versatile, in cases where the viscosity of the system changes dramatically during the mixing process. For vertical stationary propellers, with the diameters and speeds of rotation of the shafts common in practice, the shaft length is considered to be up to 1.8 m. If it is necessary to have a longer length, then the following measures are taken: 1. Install stabilizers in the form of wings welded onto the propeller blades (Figure 16a ) or in the form of a wide ring with spokes, fixed at the end of the shaft (Figure 16b). 2. Install end bearings mounted on the bottom of the vessel, as shown in Figure 17a and b. 3. Install an additional bearing in the drive (Figure 18a, or an additional remote bearing (Figure 18c).

Figure 15 - Propeller agitator drive.

Figure 18 - Additional bearings in agitator drives.

To reduce the length of the shaft, they resort to installing the drive under the vessel. Shorter shafts also have side agitators, the drive of which is mounted either on the vertical wall of the vessel, or on the bottom in the case of horizontal vessels.

Racks cast iron or welded from carbon steel. They are cylinders or truncated cones, equipped with upper and lower mounting flanges. There are cutouts in the shell of the racks for ease of installation and dismantling.

in drives end supports serve for movable fastening of the lower end of the shaft of the mixing body. The supports consist (Figure 19) of a rack 1, to which a bearing 2 is attached with bolts 7, a fixed bushing 4 is fixed in it with pins 5. At the lower end of the shaft, a movable bushing 3 is fixed with a bolt 6, which rotates together with the shaft inside the fixed bushing 4.

Bushings are made of cast iron, graphite, nylon, textolite or fluoroplast-4, other parts are made of carbon steel for neutral environments or corrosion-resistant materials for aggressive environments. From the point of view of load distribution, drives with end bearings are the most rational, however, in many cases, due to the corrosive or abrasive action of the medium, they cannot be installed. The end bearings in the apparatus operate under very difficult conditions: they cannot be lubricated, they are poorly

1- stand; 2- bearing; 3- movable sleeve; 4- fixed sleeve; 5- pins; 6,7- bolts Figure 19 - End bearings internal for vertical shafts of agitators.

available for inspection and repair. The design of the bearing must allow free circulation of fluid through it. Figure 20a shows a typical end bearing (thrust bearing). The thrust bearing shown in Figure 20b is used for lined vessels. The conical base of this thrust bearing provides it with high rigidity and protects the lining near the thrust bearing from destruction.

a) standard design; b) thrust bearing for lined apparatuses

Figure 20 - End bearings.

When the agitator is operated without an end bearing, torsional vibrations of the agitator cantilever shaft may occur, which are the result of dynamic loads on the shaft from the medium being mixed, the conditions for fixing the shaft in the supports, and the design of the agitator. If incorrectly taken into account in the design process of such important criteria reliability, as rigidity and vibration resistance, the operation of apparatus with agitators encounters a number of difficulties. If the agitator shaft is not balanced and there is play in its bearings d, then the lower end of the shaft may deviate by s. The scheme of the shaft deflection with two bearings is shown in Figure 22.

From the similarity of triangles (Figure 22) we obtain the relation:

, (1.38)

Those. shaft oscillations depend on the amount of backlash d and the ratio L/ l .

If the backlash is completely eliminated, then the value of the ratio L/ l can be limited. L/ l 4. To reduce the torsional vibrations of the shaft after the agitator is attached, it must be statically balanced. If there is a risk of torsional vibrations that lead to a malfunction of the stuffing box, or at large values of L / l end bearing is required.

Torsional vibrations cause increased wear on bearings and seals. The end bearing eliminates torsional vibrations, improving the performance of the stuffing box and bearings. Although the end bearing works in an aggressive environment, its use for the normal operation of the apparatus is necessary with a large length or high speed of the shaft.

To ensure the alignment of both bushings (Figure 19), an end bearing (Figure 23) can be used, in which the cage of the non-rotating bushing has a spherical surface, which makes it possible to set the axis of this bushing in the desired direction.

1- shaft; 2- rotating sleeve; 3 - non-rotating textolite sleeve; 4- clip.

Figure 23 - End bearing with ball cage

Mixer mounting . In the simplest designs, the blades are welded directly to the shaft. However, the elements are attached to the shaft using detachable connections. Usually the agitator consists of a hub to which the blades are welded. The hub is attached to the shaft with a key and locking devices that prevent axial displacement. If the agitator is installed in the middle of the shaft, it is fixed with a locking screw (Figure 24a), when installed at the end of the shaft - with an end nut (Figure 24b) or with the help of two half-rings that are inserted into the annular groove on the shaft (Figure 24.c).

a) set screw b) end nut; c) half rings

Figure 24 - Ways of fastening the agitators on the shaft.

When designing agitators, it is necessary to take into account the conditions of their installation. The agitators of small apparatuses (diameter 1.2 m or less) are usually assembled together with the lid and installed with it in the apparatus. They should have a minimum of detachable connections. It is advisable to make agitators for large-sized apparatuses detachable from parts of such dimensions that can be carried through the manhole of the apparatus. This makes it possible to disassemble the agitator during repair and installation work without removing the cover and drive. In all-welded devices, the agitator must be collapsible.

Couplings are used to connect the drive shaft to the agitator shaft. Normalized couplings of two types are mainly used - longitudinally split and gear.

Longitudinally split couplings are used to rigidly connect the output shaft of the gearbox (reducer motor) with the shaft of the mixing device with an intermediate shaft with any number of intermediate supports. The coupling consists (Figure 25) of the body 1 (formed by two halves), cap flanges 2 and studs 5 with washers and nuts. The connected ends of the shafts have annular grooves, on which a split ring 3 is put on, its halves are fastened with two springs 4. Half of the housing is put on the key on top, after tightening the flange studs, a rigid coaxial connection of the shafts is obtained.

Gear couplings are used to connect the output shafts of the motor-reducer and the electric motor (hydraulic motor) with the intermediate shaft with two intermediate supports. The coupling consists (Figure 26) of a toothed cage 1, reinforced with a key on the motor-reducer shaft, and a toothed sleeve 2, seated on a key on the intermediate shaft. The teeth of the sleeve enter the recesses of the holder. The coupling transmits torque, but does not connect the shafts rigidly along the axis.

Seals

A seal is used to create tightness between the fixed body of the apparatus and the rotating shaft. Depending on the physical and chemical characteristics and parameters of working media, as well as the requirements of industrial sanitation, safety precautions and fire hazard, devices for mixing liquid media are equipped with stuffing box or end seals, hydraulic seals or have sealed drive unit.

Stuffing box seal consists of a body, bottom box, pressure sleeve, stuffing box and tightening studs (Figure 27). Sealing is achieved by pressing the gland packing against a rotating shaft. A gap of 0.5 - 0.75 mm remains between the shaft and the bottom box, and a slightly larger gap (1 - 1.5 mm) between the shaft and the pressure sleeve. These gaps eliminate the possibility of shaft wear in the indicated places. Cast iron is used for the manufacture of the bottom box and pressure sleeve. In the absence of a gap between the shaft and the bottom box, the latter should be made of bronze.

1 - body; 2- pressure sleeve; 3- stuffing; 4 - thrust ring (grundbox).

Figure 27 - Stuffing box.

In some cases, the stuffing box is also a support for the shaft (plain bearing). Then the gap between the shaft and the pressure sleeve is made minimal, i.e. on a slip landing. The pressure sleeve is equipped with a device for supplying and distributing lubricant and is made of bronze or equipped with a bronze insert.

The stuffing box (Figure 28) in the middle of the stuffing box layer has a stuffing box ring, which ensures a uniform supply of lubricant along the entire perimeter of the shaft to the middle of the stuffing box. To remove heat, the stuffing box is equipped with a cooling jacket.

1 - body; 2- shirt; 3- pressure sleeve; 4- stuffing; 5- lubrication ring; 6- thrust ring (grundbuksa) .

Figure 28 - oil seal with lubrication ring.

Cotton, hemp and asbestos materials are most often used as stuffing box packings.

Below are the temperature limits at which packings can be used.

Table 1.2 - Temperature limits for gland packings.

The listed packings can be used at pressures of 0.6-4 MPa, depending on the temperature and the impregnating composition used. Impregnation serves to improve sealing and reduce the coefficient of friction of the packing on the shaft. Fat, paraffin, bitumen, graphite, liquid glass, grease, viscosine, etc. are used to impregnate the packings.

Of the above packings, fluoroplast should be noted. It has a low coefficient of friction, so its service life is several tens of times longer than that of other materials. This is also facilitated by its high chemical resistance. The disadvantages of fluoroplast are relatively high hardness (which requires a lot of effort when tightening the stuffing box) and high cost. These shortcomings are eliminated in the packing of asbestos cord impregnated with a fluoroplastic suspension.

At high temperatures (t > 300°C) dry packings are used. The most common dry packing brand AG-50 consists of 50% graphite, 45% long-fiber asbestos and 5% aluminum powder. Leakage of the sealing medium in dry packings occurs due to their porosity. Even at high compression pressures of the packing (30 - 60 MPa), it remains porous, since its constituent components - asbestos and graphite - are porous bodies.

Stuffing box seals are used in devices operating at pressures up to 0.1 MPa and temperatures up to 70 °. They cannot be used in vacuum, processing in apparatuses of toxic and explosive environments. Shaft speed - from 5 to 320 rpm.

For normal operation of the stuffing box, it is necessary that the pressing force of the lower layers to the shaft is equal to the pressure of the medium. The force of pressing the packing against the shaft acts in the radial direction, while the pressing of the packing by the pressure sleeve is carried out in the axial direction. The operation of the stuffing box is shown in Figure 29. If the stuffing box were an ideal fluid, then the axial and radial forces would be equal (P x = P y) in all its sections. However, since the packing is a deformable solid, P x<= Р у и, кроме того, сила прижатия набивки к валу будет изменяться по высоте сальниковой камеры вследствие трения набивки о вал и корпус при её деформации, т.е. при сжатии.

1 - shaft; 2 - pressure sleeve; 3- building.

Figure 29 - Scheme of the distribution of forces in the stuffing box.

The relationship between axial and radial forces can be expressed by the dependence:

The value of m depends on the stuffing material, pressure and other factors and varies from 1.5 to 5.

The law of change of the axial force along the height of the stuffing box can be represented as follows:

, (1.40)

Where S=(D-d)/2 ; f=m TR /m ; m TP is the coefficient of friction of the packing against the shaft and stuffing box housing.

In the lower part, at y=0, the equality P y \u003d P 0 is true, and the upper part, for y \u003d h, the equality P y \u003d P 0 exp (2 f h / S). The value of the axial force in the upper part makes it possible to determine the tightening force and calculate the tie rods from the cross-sectional area of the packing.

When solving equations (1.39) and (1.40) together, we obtain the law of variation of the radial force along the packing height, i.e. force of pressing the packing to the shaft:

, (1.41)

The diagram of the change in the force of pressing the packing to the shaft is shown in Figure 29. As you move away from the pressure sleeve, this force decreases. With a high gland packing height, the reduction in radial force will be significant. Efficient redistribution of the radial force can be achieved in the design of a double gland, however, a double gland is not used, since its operation is very difficult.

If the packing were an absolutely solid body, then, contrary to the assumption of an ideal fluid, there should be no pressing of the packing against the shaft. For a deformable solid, the force of pressing the packing against the shaft will be some part of the axial force. An increase in the pressing force can be achieved by a constructive technique - the manufacture of sealing packing rings with conical surfaces. For real packings, this technique is widely used.

Let us determine the power lost to friction in the stuffing box. For a packing element with a height dy, the friction force is:

After substituting the value of P x from equation (1.41) and integrating from 0 to h, we get:

, (1.43)

Taking into account f=m tr /m we have:

, (1.44)

The power lost to friction will be equal to:

, (1.46)

The friction coefficient f when the shaft rotates is smaller than when the shaft is stationary, in addition, it changes with pressure. It is difficult to take into account all this for a variety of packings when using equation (1.45), therefore, they proceed to the empirical dependence (1.46), which for practical calculations takes the form:

Table 1.3 - Influence of the geometric dimensions of the gland packing on power losses.

The width of the gland packing S, mm is determined by the shaft diameter:

, (1.48)

End seal. In this seal, tightness is achieved due to the tight compression of two parts along the end planes - a rotating and a fixed one. Tightness in such a connection can only be achieved with high quality processing of adjacent surfaces. Irregularities of 1 µm disrupt the normal operation of the mechanical seal. Friction surfaces are ground and lapped, and have a high finish (No. 10 - No. 12), they can be flat, spherical or conical. Flat surfaces are used more often, because. when finishing, it is easier to obtain a good cleanliness of the friction surface, the width of the annular friction surface should not be large (less than 6 - 8 mm).

In the chemical industry, mechanical seals are used not only for reactors, but also for centrifugal pumps. The mechanical seal for sealing the apparatus is shown in Figure 30. The ring 2 receives rotation from the shaft through the carrier 4, which consists of two halves that tighten the shaft, and through the studs 3. The stationary ring 7 is connected to the bellows. Rods 6 with a spring make it possible to adjust the preload force of rings 2 and 7, bellows 8 allows you to compensate for the beating of the shaft.

1 - body; 2 - rotating ring; 3 - hairpin; 4 - carrier; 5 - spring; 6 - thrust; 7 - fixed ring; 8 - bellows .

Figure 30 - End seal.

the seal (Figure 30) operates at a pressure of 2*10 3 - 1.6* 10 6 Pa, temperature up to 250 ° C and rotation speed up to 10 s -1 .

Advantages - less leakage than in the stuffing box, since there is no air leakage when working under vacuum, power losses are tenths of the power loss due to friction in the stuffing box, maintenance is not required, which is explained by the high wear resistance of the friction pair (and therefore durability) and good operation during shaft beats.

Disadvantages - high cost and complexity of repair.

The main unit of the mechanical seal is a friction pair. The material from which it is made must have wear resistance and a low coefficient of friction. The following materials are used: acid-resistant steel - one ring; carbon graphite, bronze or fluoroplastic is another ring. Fluoroplastic is used only in the case of low pressures and at low speeds of the friction pair, since it has a cold flow. By design, the mechanical seal can be internal and external, single and double. The seal shown in figure 30 is external.

With an internal seal, the rotating ring and pressure springs are located inside the apparatus in the working environment. A double seal has two friction pairs and is practically two single seals in series. In a double seal, a sealing medium is placed between the two friction pairs to prevent leakage and remove frictional heat.

In the chemical industry, the following types of mechanical seals are the most common: a) double mechanical seal type TD (left side of Figure 31), designed to seal the shafts of apparatus for mixing explosive, toxic, flammable, poisonous and similar media at pressures up to 0.6 MPa (type TD-6) and at pressures up to 3.2 MPa (type TD-32); b) double mechanical seal TDP (right side of Figure 31) with an integrated bearing, designed to seal the shafts of apparatus for mixing explosive, toxic, poisonous and similar media; c) mechanical seal of the TSK type, in which a bellows made of steel 12X18H10T (Figure 32) is used, designed to seal the shafts of apparatus for mixing explosive, toxic and poisonous media under pressure.

1 - fixed sealing rings; 2 - movable sealing rings; 3 - spring; 4 - body; 5 - built-in thrust bearing.

Figure 31 - Double mechanical seal type TD (left side of the figure) and type TDP (right side of the figure).

These mechanical seals are used in devices operating at an overpressure of up to 1.6 MPa or a residual pressure of at least 0.0027 MPa and a temperature of -20 to +50 ° C.

The design of the mechanical seal (Figure 32.), Consisting of a movable ring 5, fixed on the shaft with the carrier 2, and a fixed ring 6, tightly pressed by the end surface to the fixed ring with springs 4 and nuts 3. The fixed ring 6 is connected by bolts 10 with bellows assembly 7. The body 8 is closed from above by a cover 1 and is attached by flanges and bolts 9 to the cover of the apparatus.

1 - cover; 2 - spring; 3 - movable ring; 4 - fixed ring; 5 - bellows; 6 - body; 7 - bolt.

Figure 32 - Mechanical seal type TSK.

The bellows is a thin-walled tube with a corrugated surface.

The friction rings are lubricated and cooled by running water circulating in the cover cavity. Water that has entered through the sealing surface is collected in the lower part of the body, called a trap, and is discharged through the fitting. Fixed and movable rings (friction pairs) are made of carbon graphite, steels 12X18H10T, 40X13, 95X18, hostella D alloys or glass-ceramics.

Consider the operation of a mechanical seal (Figure 33).

Figure 33- The movement of the medium in the gap between the rings of the mechanical seal

The motion of the medium in the gap between the rings in cylindrical coordinates is described by the equation:

, (1.53)

In the mechanical seal, one of the rings rotates, therefore, in addition to the forces of pressure and friction, the amount of leakage is influenced by the force of inertia. If the angular velocity of rotation of the medium in the gap is determined as the arithmetic mean of the angular velocities of rotation of the rings, then equation (1.61), taking into account the force of inertia, will take the form:

, (1.65)

After integration and transformation, the leakage values are determined by the expression:

, (1.66)

Thus, increasing the speed of the shaft increases leakage when operating the apparatus under pressure and reduces leakage when operating the apparatus under vacuum.

Sealed actuators . Apparatus for mixing highly toxic, highly aggressive or flammable media are usually equipped with sealed electric drives. Drives of this type are a design in which the active elements of the rotor and stator of the electric motor are protected from the effects of the stirred medium using special insulation (wet stator) or special protective sleeves (dry stator). Sealed electric drives with "wet" or "dry" stator can be gas-filled and liquid-filled.

In a gas-filled electric drive (Figure 35), the rotor rotating in the gas cavity is mounted on rolling bearings. The stator cavity of the electric motor is protected from contact with the vapors of the stirred medium by a thin-walled protective sleeve 5. If necessary, the protective sleeve can also be installed on the rotor 11.