Production of ceramic bricks Mass preparation

Contents

Introduction

1. Chapter 1. Justification of construction site

2. Chapter 2. Process Part

2.1. Characteristics of brick production methods

2.2. Product range and characteristics

2.3. Choice of raw materials and energy sources

2.4.Process diagram description

2.5. Material balance of mixing shop

2.6. Thermal calculation of the drum dryer

3. Chapter 3. Design Part

3.1. Mechanical calculation of drum dryer

3.1.1The device and operation principle of the dryer

3.1.2. Drum Strength Calculation

3.1.3. Calculation of drum for stiffness

3.1.4. Calculation of shroud and support roller

3.1.5.Compute thrust roller

4 Chapter 4. Construction and installation part

4.1.Building solutions

4.2.Installation of drying drum

5 Chapter 5. Dryer Drum Repair

Conclusion

Literature

Applications

Summary

In this project, the mass preparation workshop of the plant for the production of ceramic bricks with the development of drum drying for clay was considered. 

The calculation and explanatory note provides an overview of the scientific and technical literature with the justification of the production method, provides the technological diagram of the designed enterprise, carried out technological calculations, including the material balance of the mass harvesting workshop and material and thermal   calculations of the dryer.

Mechanical calculations of the drying drum were made confirming the operability of this type of equipment. Equipment installation and repair issues have been developed.

Introduction

Building ceramics is a wide group of ceramic products used in the construction of residential and industrial buildings.

Among the diverse range of products, ceramic brick is the main type of local building materials. Durability, fire resistance, waterproof, complete absence of toxicity, acid resistance determined its wide use in construction. [1]

In order to reduce material costs, industrial and energy waste is used in the production of ceramic wall materials, which provides significant savings in fuel and raw materials, and contributes to solving the environmental problem. The most promising direction is the use of fuel containing waste - ashes and slags of CHP, coal processing and coal mining waste.

Of current importance is the wasteless technology of brick production developed by VNIIstrom based on CHP ashes. It provides for careful mixing of ash with dried and crushed clay. For the production of bricks according to this technology, increased requirements are placed on the initial clay. It must be uniform, have a certain size of pieces and humidity within the limits required by the regulation.

Practice has shown that the correct choice and preliminary preparation of raw materials, while observing the norms of the technological regime, makes it possible to obtain a mass with constant technological properties and stabilize the technological process at its high intensity with high product quality.

Chapter 1. Justification of construction site

Ceramic brick is the main type of building materials, so there is a great need for it.

The factory for the production of wall ceramic products is designed in the city of Yaroslavl. The design capacity of the plant is 81.6 million units of conditional brick per year. This will provide brick to organizations engaged in construction, both in Yaroslavl and in the adjacent Vladimir, Kostroma, Ivanovo and Tver regions, as well as individuals for the construction of residential buildings and cottages .

As the main raw material, loam of the Norskoye deposit of the deposit, which is located five kilometers from the plant, on the right bank of the Volga, was chosen. This clay meets the requirements for raw materials for the production of bricks of brands 150, 200 and 250, namely: ductility P = 15-17; sensitivity factor Kh > 1; B = 2123%. The addition of additives is intended to adjust the properties. The total reserves (2689 thousand m3) of the selected field, taking into account the plant's productivity, will be enough for 30 years of the plant's operation. Water supply will be carried out at the expense of the water resources of the Volga River. The fuel necessary for the operation of the enterprise comes through a gas pipeline from the Tyumen region.

The main workers at the plant will be residents of Yaroslavl.

Chapter 2. Process Part

2.1.Performance of brick production methods.

There are two methods for the production of ceramic bricks: semi-dry and plastic.

With a semi-dry method of brick production, the technological process consists of the following main operations: clay extraction, clay supply to the warehouse or directly to the production case (to the box feeder), crushing, drying, milling, mixing and moistening of masses, pressing of raw materials, firing.

Clay entering the plant is previously crushed on the same machines as in the plastic method. As a rule, clay enters the plant with a humidity of 19 to 23%, and sometimes more. Treated on coarse milling crushers, the clay is dried in a drying drum, then treated on wet milling runners and fine milling rolls.

The ground clay is thoroughly mixed with non-plastic materials and, if necessary, moistened with hot water and steam in two-shaft mixers. Moistened to 16-18%, warmed and well-mixed charge enters the silos of molding presses.

In the plastic production method, clay brought from the quarry enters the box feeder, which is designed for uniform and continuous feeding with the raw materials of clay processing machines, dosing the supplied raw materials and partially grinding large clays of clay. The clay is then loosened and crushed in knife crushers. After crushing, the charge enters the mixer, after which it enters the drying drum to remove excess moisture. For further abrasion and weight averaging, two-roll wet milling runners are used. Further grinding of the clay mass is carried out on finely ground rolls of the brand. The pre-treated mass is laid out in the charge reserve.

After the charge reserve, the mass is mixed and averaged. The strained mass is then fed by a plate conveyor into a feed box to create a buffer and a clay dosage for subsequent processing. Then the charge enters the double-shaft mixer for humidification with water or low-pressure steam. For subsequent plastic molding, a vacuum chamber forming press is used.

The formed raw material is cut by automatic units performing the operations of cutting a measuring bar coming out of the press onto products of a certain size. The cut raw material is laid on drying cars using a stacker machine.

For drying raw materials, a semi-continuous tunnel dryer is used. Tunnel kilns are used for subsequent brick firing.

The technological scheme for the production of products with a plastic method of mass preparation, despite its complexity and duration, is most common in the wall ceramic industry. With this preparation method, the clay mass is averaged and ground more fully.

This project provides a plastic production method.

2.4. Process Diagram Description

The initial stage of ceramic brick production is mass preparation. At the mass preparation site, clay raw materials and scavenging materials are mined and delivered to the plant, pre-treated, mixed to a uniform mass of a given composition.

Clay raw materials are mined in open pit. Overburden work is carried out by a bulldozer, mining by an excavator. Clay is delivered from the quarry by road and stored in an clay storage tank. The stock is required for intermediate stock of raw materials. Here, the raw materials are averaged, brought to a constant composition, which contributes to increased production efficiency .

Clay is loaded from the clay storage by the excavator onto the machines and delivered to the mass-harvesting department to the clay warehouse, pos. 2. During loading, clay is blended vertically, which contributes to the averaging of clay. Clay is supplied from the warehouse by bucket crane pos.1 to transporter pos.3, then it is supplied to clay ripper pos.4, then to cell feeder pos.5, which is intended for uniform and continuous feeding with raw materials of clay processing machines, dosing of supplied raw materials and partial grinding of large clays of clay. From feeder pos.5 clay is supplied by conveyor to drying drum pos. 6, in which drying is carried out at a maximum temperature of 800 0C. During 4045 min humidity is reduced by 5-8%

The drying drum is a welded steel cylinder. Drum is installed with slope 4-6 0 towards dried material outlet. The drum body rotates at a speed of ≈ 6 rpm. At the beginning of the drum there is a loading chamber through which material enters, also at the beginning flue gases are withdrawn. At the end is a discharge chamber through which dried clay is discharged. On the loading side, the furnace chamber pos.14 is attached. Clay drying is carried out by direct flow. Dried clay enters the screen pos. 16. The fraction of clay particles passing through the screen screen is fed by the conveyor pos.17 to the dry clay hopper, pos. 18. Large pieces of clay that have not passed the screen screen are ground on rolls pos. 15 and are again fed for screening.

Exhaust flue gases are cleaned from clay particles in cyclone pos. 7 and by means of exhaust fan pos. 8 are released into the atmosphere.

Quartz sand from wet sand hopper pos. 13 is fed by conveyor 12 into drying drum for sand pos. 11. Dried sand enters the screen pos. 21. Agglomerated sand particles that have not passed through the screen screen enter the crusher pos. 22 and return to screening. The sand which passed through a roar sieve the conveyor of poses.20 moves in the bunker of dry sand of poses. 19. Exhaust flue gases are cleaned from sand particles in cyclone pos. 10 and by means of exhaust fan pos. 9 are released into the atmosphere.

A mixture of dry sand and dried clay passes through the stone-separating rolls pos. 25. To further abrasion and average the mass, we use two-roll wet runners pos.26 and a two-shaft mixer pos. 27. Further, grinding of sand-clay mass (charge) is carried out on fine milling rolls pos. 28. After passing the magnetic separator pos. 29 charge is supplied to bunkers of charge reserve pos. 30. After laying in the charge reserve, the charge goes to the raw material moulding.

2.5. Material balance of mixing compartment.

2.5.1.The initial data:

A. Productivity - 26 million pieces of conditional brick per year.

B. Norms of loss and marriage by redistribution:

loss on stone release - 0.1%;

transportation losses - 0.1%;

clay loosening losses - 0.05%;

dosing losses - 0.1%;

grinding losses - 1.0%;

blending losses - 0.05%;

moulding scrap - 0.5%;

Drying scrap - 2%;

roasting failure - 2%;

battle in stock - 0.1%. [9]

B. Brick dimensions 250 × 120 × 65 mm.

G. Brick mass:

burnt - 2.1 kg;

dry - 2.2 kg;

shaped - 3.2 kg.

D. Humidity:

quarry clay Wgl - 25%;

clays after drying - 18%;

clay mass before moulding - 16%;

residual brick after drying - 0.5-1%.

E. Shikhtova composition:

clay - 86%;

sand - 14%.

2.6. Heat engineering calculation of drum dryer

2.6.1. Source Data

Capacity dried 24360 kg hour on clay with a moisture content of 25%

Humidity: initial W1 = 25%;

final W2 = 18%.

Density of material αc = 1900 kg/m3.

Fuel - natural gas from a gas pipeline from the Tyumen region.

Clay temperature

: initial = 16 wasps; the final temperature is taken equal to the temperature of the wet thermometer, since the moisture content of the material at the end of drying is high.

Heat carrier temperature: initial = 800 wasps;

final = 98 wasps.

Air parameters before entering the furnace:

- relative humidity φ0 = 70%;

- t0 temperature = 20 wasps;

- moisture content d0 = 10.0 g/kgf dry air.

Drum inclination angle α = 3 °

The drying drum operation mode is continuous.

For drying, we take a direct-flow system of coolant movement to reduce dust collection. The drying agent is a mixture of atmospheric air and flue gases. Internal devices system vane

Chapter 4. Construction and installation of equipment

4.1. Construction solutions

Mixing section is located in separate housing. The building is a two-story building 185.5 m long and 144 m wide. The mixing section occupies part of two spans from the edge of the building. The distance between the load-bearing columns is 12 m. The width of the transverse spans of the hull is 24 meters. The railway tracks are located next to the building.

The second floor is located at an altitude of 8.4 meters from the zero level of the first floor. In the building there are single-beam electric cranes with an electric elevator, for them installation of crane tracks is provided.

The height of the spans of the building from zero level is 19.2 meters. Height to load-bearing structures of the roof of the mixing section building from the zero level of 26 meters.

Material of body frame is all-metal. The foundations of the columns are reinforced concrete, stepped, monolithic. The pitch dimensions of the columns in the middle columns are 6 meters. Crane tracks are attached to the metal roof frame on the second floor of the building and to the columns on the first.

Corrugated iron with a corrosion-resistant coating with a layer of foam is used for external walls and roofs. In the lower part along the perimeter of the body at a height of up to 1 meter from the zero level, continuous panels with a length of 6 meters from cellular concrete with a thickness of 240 mm are accepted. Roof is made of corrugated iron with corrosion-resistant coating with foam layer. The roof is located at an angle to the plane, so the drainage is carried out by gravity into special pipelines and a collector. The building provides side windows around the perimeter of the building measuring 1.5 × 2 meters.

Metal working platforms are provided in the housing. There are no basements in the building. Solid reinforced concrete stairs. The internal walls in the building are provided in the form of a solid panel 6 meters long of cellular concrete with a thickness of 240 mm. The floors in the building are concrete. Internal decoration of the room provides for plaster and painting, corrosion protection of bearing structures.

Ventilation, heating of premises, as well as water supply and sewerage are provided in the housing and in the mixing section.

4.2. Dryer drum installation

The drying drum installation is a complex of organizational-preparatory and mechanized works.

Mechanization of production requires careful design development, which should include the most rational methods and means of mechanization. The most labor-intensive operation of mounting drying drums is the installation of the housing. Installation techniques depend on the type of part of the drum being delivered to the installation site. The method of delivery of units and equipment included in the drying drum set to the installation site depends on their size and vehicles. A particular difficulty is the transportation of the dryer body, which is delivered with separate shells (rings l = 2 m), tertiaries (third part along the shell around the circumference) or rolls. The installation of the drying drum can be carried out in various ways, depending on the installation conditions and the presence of lifting vehicles. Installation using an estokada and a special trolley, a rack is built along the length of the drum

with rail tracks, along which the dryer unit is moved by a winch on a special trolley. Such installation requires significant costs of materials and labor for the construction of estokada.

Erection with derrickkrep is simple, while the need for estokade does not fall, as well as in other lifting mechanisms. Prior to installation, all units and parts of the dryer drum are inspected: bands, shells and their parts are welded and checked, and small units are assembled into larger ones.

First, shells are assembled and welded into large blocks. To assemble shells, a bench is made. Ring edges of shells before welding are adjusted by means of clamp. Longitudinal and annular seams of shells are welded by TS17M automatic machine or by electric slag method according to manufacturer's technology.

After completion of welding, external inspection and correction of detected defects, at least 5% of the length of all joints is checked by radiography. Sections of stitches with defects are cut or melted, brewed again by hand and re-illuminated. At the same time as shells are welded, shrouds are assembled and installed on shroud shells. The shrouds on the mounting platform come from two semi-rings, which before welding are installed with a gap of 3032 mm in the lower part of the joint and 4042 mm in the upper part. Note here that position of half-rings is checked by level and ruler to be displaced by jacks. Joints are heated to temperature 100 0 with gas flame and welded. Then they are treated (cleaned) and heated each joint with gas burners, annealed at a temperature of 550-600 0C.

The entire processing process lasts 610 hours. After that, bandage diameters are checked by metrometric stillmosis. Tolerances for outer and inner diameters ± 2 mm, and side plane fracture up to 1 mm. Then the shroud is fitted with a crane on a shroud installed vertically on the platform. In vertical plane shroud is screwed with three screw jacks, lifting capacity 15 t. Base of shroud alignment is outer diameter of shells in vertical direction and ends of shells in axial direction.

The shroud end planes shall be perpendicular to the shell surface. The main condition of installation is the coincidence of the shroud axis with the shell axis, and this is quite permissible. Bandage is fixed in direction of longitudinal axis of shell with stops.

Clearance between stops and end face of shroud is 2-3 mm, at that stops are not finally welded. This is done after checking the axis of the furnace body on roller supports. At the same time, halves of the rim gear are assembled and installed on the shell. Both halves of the rim gear are connected by tightening bolts with special rings installed in hot condition on shoes on both sides prior to attachment of the rim gear to the shell. In the support legs of the rim gear, holes are placed and drilled, then the leg is connected to the rim of the rim and before being put on the shell, annealed and fixed to the rim of the gear. Position of rim gear is placed on shell. According to this marking, 6-8 metal posts are installed near the shell, which pre-fix the position of the rim in the axial direction, if necessary, adjust the position of the latter by installing gaskets under the metal posts. In radial direction to the seat the shells are welded in four diametrically arranged places of beams, which are guides when the rim is put on the shell. After preliminary alignment of rim gear paws are squeezed, they are adjusted to shell with wedges and paws are electrically tucked to shell.

Other nodes are similarly strengthened.

During the construction of foundations, planks with applied axes and high-altitude benchmarks should be laid in them. Axial lines on the support foundations shall be inspected and applied before commencing erection work taking into account drum extension during heating. Foundation elevations are checked and position of foundation plates and support rollers in vertical and horizontal planes is determined so that furnace axis is rectilinear and corresponds to accepted slope. Axis of body is fixed in horizontal plane with wire stretched along axis of foundations.

After adjustment of roller supports and welding of fixed blocks of shells, they are installed on roller supports and special metal supports, starting from rim gear, successively in the direction of cold and hot housing. This arrangement of the shell units makes it possible to eliminate the misalignment from the drive towards both ends of the housing and simultaneously mount the drive mechanism, thereby shortening the start-up time of the rotating housing. Housing units are joined by tie pins, wedges or special devices. Each joint is fixed with 6-8 studs M42 with check nuts. After preliminary straightness check, mounting blocks are gripped by electric welding. Ring joints of mounting units are welded after check of axis in horizontal and vertical plane, check of position of rim gear and shrouds on roller supports, turning body with winches.

Only then, with positive results, the crown gear is finally fixed to the body and the shroud stops are welded. At the same time the rim gear is fixed on the housing with its binding to the band having control rollers with accuracy ± 5 mm.

Drive mechanism is installed immediately after installation of bottom-rim unit of shells. Engagement of teeth of rim and under-rim gear is checked beforehand in four points (through 90 0) on circumference of rim gear, on tooth of the latter located on straight connecting centers of both gears. Clearances are adjusted and clearances and skews are eliminated by shifting undercarriage gears. Skew value is measured by probe. Coaxiality of main and auxiliary reduction gears is provided by universal accessory.

Second auxiliary reduction gear and temporary electric motor are installed for rotation of housing during installation and welding operations.

After check of beating, adjustment and fixation of bands, check of end stops, control rollers are finally installed, leaving clearances between them and band within 1015 mm, and then straightness of the assembled body is checked. This check is carried out three times: first before installing the drive, then before welding the mounting joints and finally after their welding.

Radial run-out of welded joints, as well as run-out of cold and hot ends of the housing shall not exceed 10 mm.

After final check and adjustment of straightness of housing, run-out, radial, lateral clearances in engagement of rim and sub-rim gear are checked again. Then anchor bolts of frame, motor and reduction gear are poured with concrete and electromagnetic brake is mounted. Alignment of all parts of drive mechanism is checked again after concrete hardening. Then the body head with nozzle, lubrication system and other equipment are mounted.

Chapter 5. Dryer Drum Repair

During overhaul of drying drums, parts of the body are usually replaced or restored, roller support parts are repaired and body, shrouds are adjusted, parts of the drive mechanism, recuperators and their fasteners are replaced or repaired, transporting and feeding mechanisms are repaired; besides, furnace body is checked and straightened (axis is adjusted).

During the operation of the drying drum, special attention should be paid to the condition of the seals, lubrication of friction parts (rollers, drive). It should be ensured that the drum does not move or tear away from the support rollers.

Current repair of drying drum is carried out with its incomplete cooling so that after stopping it can be quickly put into mode. During repair all units are revised, small parts are replaced, bearing seals are repaired, and support rollers are changed if necessary.

During the middle repair, the unit is partially disassembled, cleaned, washed and individual units and parts are changed, as well as individual parts are shaved and lapped, checked for accuracy and adjustment of the units. At that, drive mechanisms, compaction are repaired, drum body and support rollers are repaired.

Before performing medium and major repairs, all major repairs are carried out with the preparation of a work organization project. The project is drawn up on the basis of a list of defects; it provides for methods of work, the need for rigging, tools and devices, determination of their installation and attachment places, arrangement of scaffolding, number and arrangement of crews.

Lifting and transportation mechanisms are selected on the basis of maximum weight and height of lifting of parts and assemblies, as well as conditions of arrangement of repaired drum. For repair, bridge cranes, four-way lifts, car cranes and other lifting mechanisms are used to transport rollers, shrouds and shells of trailers with a carrying capacity of 40 tons.

In addition to lifting and transportation mechanisms, stands and accessories are necessary for repair work.

Hydraulic jacks, winches, worm rods, blocks are also used in the repair of the drum.

The overhaul in terms of volume and maintenance is approaching the restoration repair. During overhaul, part of body is replaced or restored, roller supports, shrouds, parts of drive mechanism, transporting and feeding mechanisms, fans and smoke pump are repaired or replaced.

The main repair units of the drying drum are: the drum body, roller supports, shrouds, rim gear, drive, feed mechanisms, fan and smoke pump, electrical equipment.

Before being handed over for repair, the drum should be completely cleaned of clay, dust, all moving parts must be wiped, oil is removed from the reduction gears and bearings. During disassembly of the units, the state of the parts and assemblies is checked in order to refine the data sheet. Cooled drying drum is subjected to instrumental check in vertical and horizontal plane and, according to obtained data, diagram of drum axis position is made.

Before the drum stops and cools, the reference marks on the drum foundations are checked, as well as the distance between the bands, and the perpendicular of the ends of the bands to the drum body is checked with an elbow.

After the drum stops, the gaps between the projections of the under-landing shoes and the ends of the shroud are measured, then the diameters of the shroud are determined and entered into the circuit.

Before the dryer stops, an estocade is mounted parallel to it, on which new parts of the body are fully assembled and welded. The dryer is then stopped, the parts to be replaced are cut and removed. After that, old roller supports are repaired or (if necessary) new ones are installed and new parts of the drum body are rolled over from the estokada. All operations are performed by different lifting mechanisms.

The drying drum body is repaired in the following sequence: the axis of the drum is checked and adjusted in vertical and horizontal planes; screw struts and temporary roller support are installed in the housing on both sides of the cut-out section for stiffness.

Housing is placed for cutting of damaged section; replacement shell is fixed by slings to crane hook, damaged section is cut and removed, and edges of cut are prepared for welding.

A new shell is installed and joined to the edges of the body and, after alignment, is gripped with electrodes, and then welded. All seams shall be branded and externally inspected, and about 5% of seams shall be inspected by X-ray or ultrasound.

Repair of the housing ends with re-leveling and adjustment of the position of the furnace axis.

Shrouds shall be replaced if their wear on thickness exceeds 20%, as well as in the presence of through cracks, which cannot be welded. Small tapering and inclines are eliminated in place by grinding, without removing the shroud from the oven.

If the shroud also has damage, then before stopping the drum for repair, prepare a new shroud together with a new shroud before centering it with shoes, followed by final alignment in place. Cracks found on the bands are brewed by welding with annealing in place.

Support and control rollers wear their surfaces. If the rim thickness decreases by more than 20%, taper and cracks appear, the rollers are replaced. To remove the support roller from the support in order to release it, it is necessary to lift the housing. This is done by jacks that are installed under the bands or under the body of the dryer (through wooden liners), as well as a metal wedge 3040 mm thick.

The roller is removed and removed by towers, winches, cranes. The existing defects of the support rollers are eliminated by a groove, followed by grinding.

If the axis of the removed roller has great wear, it is replaced by a new one made with a tolerance for a hot nozzle.

When the surface of the roller is worn, the latter can be built up. When assembling support rollers, special attention is paid to the correctness of their installation. Position of rollers is checked by level or special wedge with inclination angle of furnace axis to horizon.

Repair of reduction gear drive consists in restoration of reduction gear, bearing and rim gears.

The crown and sub-crown gears are replaced with 30% tooth wear. These gears are repaired and restored by conventional methods. The diameter and ovality of the rim gear are checked in advance in order to take it into account during installation. The axis of the gear must coincide with the longitudinal axis of the furnace. Radial and axial run-out of the gear must not exceed 0.08 module. Radial run-out of gear secured to housing by springs parallel to furnace axis is eliminated by adjusting thickness of gaskets under springs. The engagement gap must not exceed 0.25 module (810 mm), this value takes into account the increase in the diameter of the rim gear during heating, the shrinkage of the drum during wear of the inserts.

If the radial clearance in the teeth is small, and it is impossible to move the shaft of the undercarriage gear from the axis of the housing, then, shifting the support rollers, lift the housing on all supports. The newly installed springs are screwed with an elbow over the surface of the nearest shroud.