1. Briefly describe the performance of sintered brick tunnel kiln

　　1. The tunnel kiln is a relatively advanced kiln for the continuous production of sintered bricks. It has been widely used, developed and promoted in the brick and tile industry in my country. There are many types of kilns, and there are three types of types: one is roasting dry billets. The second is the primary firing tunnel kiln for firing semi-hard plastic and hard plastic extruded bricks; the third is the second firing tunnel kiln for firing softer extruded bricks. In terms of cross section size, there are large, medium and small sections. Among them, the 1.5-2.5m cross section is a small section, the 2.5-6m cross section is a discontinuous section, and the 6-10m cross section is a large section. Now our country has developed a tunnel kiln with a super large cross section to produce sintered bricks, the cross section size of which exceeds 10m. These kiln types are available for our investors to choose.

　　2. The characteristics of the tunnel kiln are: high degree of mechanized operation, high degree of automation, improved labor operating conditions, many auxiliary equipment, high continuous productivity, and good heat utilization economic performance. Especially after the popularization and application of mechanized code blanks and microcomputer automatic operation and monitoring of kiln production temperature and pressure, the advantages of tunnel kiln roasting and sintering products have been demonstrated. Therefore, certain material and technical conditions must be met to build a tunnel kiln. At present, most of the tunnel kilns use solid fuel coal, and some places also use heavy oil, natural gas, electricity, etc. as combustion fuels.

　　3. The working principle of tunnel kiln roasting is based on the reverse movement of the bricks and the gas, through the preheating, roasting, and cooling of the bricks for heat exchange, so that the bricks are baked into a sintered product.

　　2. The structure and production of tunnel kiln

　　1. The tunnel kiln is a through tunnel. The product is fired in the tunnel. It is called tunnel kiln for short. The tunnel kiln can be divided into preheating zone, roasting zone and cooling zone (including heat preservation) according to the length direction. It is generally called the "tunnel kiln" Three belts". For the primary firing tunnel kiln, there is a drying section before the preheating zone. For example, the second code firing is then manually coded on the firing kiln car on the basis of the dried bricks for roasting, which is called the second code firing.

　　2. A track is laid in the tunnel kiln. The kiln car loaded with bricks enters sequentially from the entrance of the kiln and moves relative to the airflow in the kiln. The kiln car travels on the track and is heated to the highest temperature by the preheating zone and the roasting zone, and then heat preservation. And cooling is taken out of the kiln, which is the finished product.

　　3. The fuel used for roasting enters the kiln to burn and heat the sintered bricks from the coal feed hole or combustion chamber or burner of the roasting zone. The exhaust gas is discharged from the preheating zone through the flue duct of the exhaust hole. Part of the hot air that becomes hot after cooling the product is drawn from the hot air outlet for drying, and part of it enters the roasting belt for combustion support. 4. In the roasting tunnel kiln, the firing temperature of the products is about 1000℃. In the selection of the kiln body structure, it is necessary to select better refractory materials for the firing zone to build the kiln wall and kiln roof, and the preheating zone and cooling zone Common refractory bricks, or clay or shale sintered bricks can be used. The flat ceiling tunnel kiln uses inverted T-shaped refractory concrete hanging slabs or hanging beams. The hanging beams include concrete and steel structural hanging beams.

　　5. In order to have good sealing and heat preservation performance of the kiln and avoid the influence of air leakage on the roasting process in the kiln and the influence of high temperature gas on the metal structure of the lower part of the kiln car, the two walls of the kiln are equipped with sand sealing grooves, and the grooves are filled with sand. Both sides of the kiln car A sand sealing plate is inserted into the sand sealing groove to block the mutual flow of upper and lower air currents. Both the kiln wall and the kiln roof are equipped with thermal insulation and refractory materials, so that the thermal conductivity in the kiln is reduced, and the heat is not lost, so that the heat source can be effectively recycled to achieve the function of energy saving and consumption reduction. A waste heat utilization system is installed on the structure of the tunnel kiln, and the extracted hot air is used for drying bricks in the drying room or as heating in winter in the northern area. Generally, a kiln door is installed at the inlet and outlet of the kiln to make the operation in the kiln stable and free from external influences.

　　6. ​​The supporting equipment of the tunnel kiln includes import and export kiln doors, push-carriage machines, electric carriages, kiln cars, return winches, exhaust fans (chimneys), cooling blowers, heat extraction fans, heat exchangers and other auxiliary equipment.

　　7. The working system of the tunnel kiln is mainly determined by the following aspects. One is the main size of the kiln. It is determined by the types, specifications, output of the roasted products, the water content of the kiln body, the roasting curve, the rejection rate and the performance (composition, calorific value) of the fuel used. The second is the length and cross-sectional dimensions of the kiln. It is determined by the type of roasted product, the output and the performance of the fuel used. When the size of the cross section, the density of the code kiln and the roasting time are constant, the longer the kiln, the higher the output, and the more stable the roasting process, which helps improve product quality. Therefore, the kiln should be used when roasting sintered products with relatively high sensitivity to raw materials. The length of the furnace is appropriately extended. However, the longer the kiln body, the longer the gas flow, the increase in resistance, the larger the preheating pressure, and the increase in excess air in the kiln, which increases the power consumption of the smoke exhaust equipment. The third is the kiln working system. It is determined by the product firing curve, product characteristics, fuel performance and kiln construction conditions. The preheating zone of the tunnel kiln generally only has a smoke exhaust fan to discharge the smoke and adjust the temperature. The roasting belt is generally equipped with coal feeding holes, and the distance between each row is generally between 0.7-1m. The cooling belt is fed with cold air and discharged with hot air. The cooling air passes through the air outlets on both sides of the kiln or on the top of the kiln, using axial fans or centrifugal fans. The fan blows in. Cold air inlets can also be opened on both sides of the kiln, and cold air can be sucked in from the kiln tail and cold air inlets by air pressure. The fourth is the temperature control and pressure monitoring of the roasting kiln. The firing temperature is the most important parameter in the roasting process. It has an impact on the quality of the product, the output and the service life of the kiln. Therefore, the control of temperature is very important. To monitor the temperature of the kiln, the main parts are the top temperature of the preheating zone, the roasting zone and the cooling zone. The pressure in the kiln is the most important parameter to indicate whether the kiln is normal or not. After the pressure system in the kiln is determined, the ventilation volume in the kiln can be basically determined, which also determines the productivity and product quality of the product. Changes in ventilation will affect the rise and fall of the furnace temperature. The temperature change of the kiln requires a long process, but the pressure change is instantaneous, and the pressure monitoring must be set up and down in the same part.

　　3. Precautions for the construction of key parts of the tunnel kiln

　　The quality of the tunnel kiln during the construction process is that it will directly affect the life of the kiln in the future. First of all, we must know the structure of the kiln body and the direction of material selection according to the design intent. In the quality control link of the process, each pass is well controlled, reasonable construction procedures are formulated, and the principles of first underground, then above ground, first inside and outside construction are followed to complete a series of processes, and finally reach the ideal state of production. However, the kiln is a thermal equipment, and it must be built in the workshop to avoid rain. 1. Purchase of kiln body engineering materials. One is refractory materials. It is the main material for the kiln body. The refractoriness of refractory bricks should not be lower than 1730℃, and the refractoriness of refractory clay should not be lower than 1580℃. It is the main material of the kiln structure, as well as some high-temperature parts or special functions. Sexual material. For refractory materials to be successfully used under high temperature, they must have a good structure, such as: thermal properties, mechanical properties and service properties. That is, it has high refractoriness, softening temperature under load, volume stability, thermal shock resistance and chemical resistance. In order to withstand various physical and chemical changes and mechanical effects. Only in this way can the requirements for the use of thermal equipment and parts be met. The chemical composition is its mineral composition. The tissue structure is the apparent porosity, volume density (bulk density). The mechanical property is the compressive strength at room temperature. Thermal performance is thermal expansion and thermal conductivity. High-temperature performance is refractoriness and high-temperature structural strength. The second is "earth materials". All soil materials are mainly sand, stones, and red bricks. Sand mainly controls its mud content and mineral structure. Limestone should not be used for stones. Red brick is mainly to improve its compressive strength, which is required to be above 10MPa. The third is metal structural materials. There are two types of ordinary steel and heat-resistant steel, and a reasonable steel material should be selected according to different temperatures and parts of use. The fourth is thermal insulation materials and unshaped materials. Such as insulation felt, cotton, brick, ceiling board, etc. The quality of these special materials must be strictly controlled. When they are used at the factory, they must be inspected before use, and they must be strictly checked and accepted in accordance with relevant national regulations.

　　2. Reasonable construction layout. The first is to prepare for construction, plan the construction layout, adjust the construction schedule and construction labor organization, make a good material supply plan, and "stuck" the inspection of materials and equipment into the warehouse quality inspection link and other meticulous work. The second is that the kiln foundation project and the plant foundation should be constructed at the same time. The kiln plant should be built first, and then the kiln construction should be carried out. This is conducive to handling the relationship between the two foundations underground, and is also conducive to the excavation of the foundation trench. Especially in the rainy season, the construction of the kiln in the kiln is beneficial to speed up the construction progress of the project, is conducive to the control of the project quality, and can ensure that the fire-resistant and insulating materials are not exposed to rain. The third is the laying and installation of tracks in the kiln. The track must be installed after the foundation is completed. Otherwise, kiln wall masonry is not allowed. The elevation of the track surface and the track centerline are the elevation and center reference points of all projects. The measurement and positioning of other parts of the kiln must be based on the elevation of the track surface and the centerline of the track. As a benchmark. The fourth is the construction and installation of sand sealing grooves. Sand sealing grooves have many types of structures. Such as section steel structure, refractory structure, reinforced concrete structure, cast iron structure. Regardless of the structure used, the installation dimensions must ensure that the inner wall of the sand seal groove and the track center control dimensions and elevation dimensions shall not exceed +2, -3mm. The fifth is kiln wall masonry. 1 The materials used on the kiln body must have a factory certificate, enter the site for random inspection and screening, and reject unqualified products from the construction site. 2 Refractory brick masonry. Furnace builders must have professional construction tools, such as trowels, spirit levels, line sinkers, rubber hammers, cutting and grinding portable machines, etc. It is forbidden to use hammers to chisel bricks on the masonry. 3 When building the kiln wall, a model pole should be set up at the expansion joint, engraved with the standard size of brick thickness, and then built according to the standard. 4 The position of the expansion joint should avoid the stressed parts and the kiln body frame to avoid affecting the strength. When building expansion joints, attention must be paid to keeping the inner and outer layers closed and not communicating with each other. The upper and lower brick layers are left as locks and staggered from each other. If there are brick layers of different types of bricks in the kiln wall, it should be built to a certain height for 4-5 layers, and for red bricks, 6-9 layers should be laid by one layer. After the kiln wall has been built, refer to Table 1 for inspection and control. Sixth, kiln roof construction. The kiln roof has two structures, namely, the arc roof structure and the flat ceiling structure. The kiln whose body section is larger than 3.3m should adopt a flat ceiling structure. The flat suspended ceiling is divided into a refractory brick assembly structure and a prefabricated installation structure. Regardless of the structure, the first control is the size of the top structure, and the second is the method of masonry and hanging, which is the key to quality control. For example, the arc roof should be prefabricated and pre-arranged, the size of bricks and mud joints should be unified, select the positive and negative deviations to occlude, determine the type of brick lock, for the arc roof larger than 2m, divide it into 2-3 bricks at different angles at the same time After closing and locking the roof, a comprehensive inspection should be carried out after the vault is locked to prevent broken bricks from being caught on the kiln roof to eliminate hidden quality hazards. Such as flat ceiling structure, when installing prefabricated hanging parts on the kiln roof, attention should be paid to first, the hooks should be vertical, and the hooks are not allowed to hang obliquely, and the second is the high temperature refractory fiber blanket filled in the board seam, which should be filled while the hanging board is installed. The thickness of the board should be 3 times of the board seam to ensure a tight seal. The lower part of the blanket is flush with the lower part of the hanging board, and the upper part should be 50-100mm from the upper board surface. The third is the hanging board placed on the top surface of the kiln wall. The space should be padded with refractory fiber blanket, and the thickness should be twice the thickness of the gap. Regarding the hanging slab, the main beam and the secondary beams are all metal structures, and some design departments also adopt some concrete beam structures. Regardless of the hanging beam structure, the most important thing is to pay attention to whether the material properties selected can meet the necessary conditions for use at room temperature. Be accurate when installing the dimensions. The pot and hook should be destructively tested before installation. Check whether the material and structure of the material meet the working requirements and conditions under the hot state of the kiln top.

　　Fourth, the use of fired brick tunnel kiln method of attention

　　1. Before drying the kiln, do a comprehensive inspection of the kiln structure. First, check whether the structure is completed in accordance with the design requirements, whether the use functions of each part are complete, unobstructed, and free of obstructions, each tuyere, flue, hot air duct, and pipe section Comprehensive restoration of important parts such as outlets, discharge outlets, operating equipment, kiln cars, jacking machines, drawing machines, fans, temperature control, electric control, fastener columns, tie rods, sand pipes, sand sealing tanks, kiln doors, etc. Check. The second is cold debugging and operation, the main purpose of which is to eliminate undiscovered problems before ignition, to ensure that the ignition is put into production smoothly, and to allow production technicians to control the use of the kiln and the performance of each part. I would like to remind users that this link must not be ignored.

　　2. After the cold run trial run, a reasonable kiln debugging plan must be formulated. The first is to formulate the baking curve, which should be implemented according to different types of kilns. The purpose of the drying kiln is to remove the moisture in the kiln, and debugging is to achieve the roasting performance of the kiln that can adapt to the production of products in the normal production process. During the baking process, keep abreast of the relationship between dynamics and statics. The key point of the kiln is to deal with the dynamic response during the drying adjustment process, and pay attention to the treatment method at any time. If the kiln system and temperature plan are unreasonable, many unfavorable chain reactions will occur. Such as kiln body cracking, thermal turbulence, kiln body leakage, resulting in poor sealing performance of the kiln body, shortening the service life of the kiln, deformation of the kiln body structure, sometimes causing partial collapse, uncontrollable pressure and temperature, and poor adjustability, etc. , Easily lead to paralysis of the entire production line.

　　3. It is necessary to have a group of technical management personnel and operating workers who understand technology, understand management, understand operation, can repair and handle general accidents, and can promptly eliminate problems in order to ensure that the kiln can operate normally.　4. The roasting thermal system and operation must be mastered, and a reasonable roasting system must be worked out according to the raw materials of different sintered bricks. Such as temperature system, roasting temperature and heat preservation system, cooling temperature control system to prevent cold cracking, pressure system, control of atmosphere properties, kiln density of kiln cars, speed of entering and exiting cars, etc.　5. Pay attention to the operation of the supporting equipment of the roasting kiln. Such as the maintenance and repair of fans, exhaust fans, exhaust fans, cooling fans, kiln cars, jacking machines, shuttle cars, and pulling cars. These equipment must be recorded during operation, and the operating conditions must be controlled at any time, which is conducive to the handling of emergencies.

　　6. The master control room of the roasting kiln. For example, the data reflected by the instrument and the circuit system should be recorded truthfully and should not be rewritten at will, which is beneficial to the working system of the kiln and provides the operators with production control operation guidance.

　　7. Develop kiln production and operation manuals. Distribute the technical performance, technical parameters, precautions, operation steps, safety regulations, etc. of the kiln to the production workers, so that they are familiar with the use of the kiln as a thermal equipment. In order to avoid human accidents, control the production characteristics of the kiln at any time.

　　8. Do a good job in the overall inspection and maintenance of the kiln. It is related to the service life of the kiln. The production capacity of the kiln, whether the kiln can reach the designed output, and whether the products produced meet the requirements, it has an important role in production. The first is whether the passage in the kiln is unblocked, whether there are obstacles that affect the cooling system of the vehicle bottom, and whether the cooling fan under the vehicle is running well. The second is the actual operation of the track in the kiln, whether there is a deformed part, will it affect the operation of the kiln car. The third is the sand sealing groove in the kiln, to see if there is any deformation, will it affect the sealing. The fourth is the sealing condition between the kiln car and the kiln car. Fifth, whether the operating system of the kiln car bottom is working properly and whether the car can be transported to the required position. Sixth, whether the cooling air system is operating well. Seventh, whether there is any obstruction in the ventilation duct, and whether the ventilation of the whole kiln is unobstructed. Eighth, whether the waste heat extraction and smoke exhaust system work normally, and whether it affects the normal operation of the kiln. Nine is whether there are cracks on the kiln body, whether it will cause air leakage in the kiln, and whether it can be repaired. Ten is whether all the insulation performance of the kiln body