How to dry and fire clay bricks in clay brick kilns ?

When using tunnel kiln to burn bricks, various parameters used in production should be determined according to the basic properties of raw materials.

The firing output of the kiln is that the performance indicators of the fired product meet the requirements of the national standard, not just how much is fired, and the output of the kiln is how much. Some kiln-fired products are only 3mm~4mm on the surface, but the inside is not completely fired. Such products that do not meet the requirements of the national standard cannot be used as the basis for calculating the output of the tunnel kiln.

The length, width and height of the kiln are calculated according to the output of the kiln. When calculating the length, width and height of the kiln, the heating and cooling rates of the raw materials, the firing time of the raw materials, the highest firing temperature and the firing temperature range should be considered. And other factors.

The tunnel kiln should also have a complete working system, and various parameters of the working system must be calculated in detail, so as to ensure the normal operation of the tunnel kiln, so as to achieve the purpose of correct construction and correct use of the tunnel kiln, and to ensure that the tunnel kiln burns In the process of reaching the target and reaching the production.

2. Reasonable layout of the tunnel kiln system to make the firing stable.

According to the definition of tunnel kiln, tunnel kiln should be equipped with ventilation system, fuel combustion system, vehicle entry system, and sealing system. These subsystems constitute the working system of tunnel kiln. The close cooperation of each system can make the tunnel kiln work normally.

According to the requirements of the firing atmosphere in the kiln, the number and position of the fans used on the kiln are equipped, the air pressure of the fans is determined according to the shape of the fired products and the density of the kiln, and the ventilation volume of the fans is determined according to the output.

According to what kind of fuel is used, the method of fuel combustion system, what kind of combustion equipment to use, and the arrangement position and quantity of combustion equipment should make the temperature in the kiln as uniform as possible. The main contents included in the entry system are entry mode and entry time interval.

The sealing system includes the sealing between the kiln car and the kiln body, the sealing between the kiln door and the kiln body, the sealing between the pipeline and the kiln body, and the sealing between the kiln cars. It is isolated to form a good firing space inside the tunnel kiln, so that the semi-finished product can be fired into the finished product inside the kiln.

The division of the three zones in the firing process of the tunnel kiln should be carried out according to the basic properties of the raw materials, and should not be arbitrarily divided, so as to ensure the normal production and stable operation of the tunnel kiln.

3. Recognize the importance of kiln car and ensure the stable quality of fired products.

The kiln car is an indispensable equipment in the production process of the tunnel kiln, and it is also the key equipment related to the performance of the tunnel kiln and whether it can be used normally.

In order to make the kiln car play the role of key equipment, the first thing is to maintain a good seal between the kiln car and the tunnel kiln body, so as to completely isolate the inside of the kiln from the outside of the kiln, so that the cold air outside the kiln cannot enter at will In the kiln, the hot air in the kiln will not leak into the kiln, so that the firing process in the kiln can be carried out smoothly.

Secondly, the seal between the kiln cars should also be reliable, the reason is as mentioned above. Third, the operation of the kiln car should be stable, so as to avoid the occurrence of such phenomena as kiln collapse, uneven firing, and difficulty in entering the car. Fourth, the thermal insulation layer on the kiln car is very important. If the thermal insulation layer of the kiln car has a good thermal insulation effect, the temperature in the kiln will be consistent, the quality of the fired products will be uniform, and the color will be the same. If the thermal insulation effect of the kiln car is not good, Then, the temperature difference between the upper and lower sides of the kiln will be large, and the fired products will be cooked on the top and cooked on the bottom, or cooked on the top and under the coke. In short, the product quality is uneven and the color difference is large.

Some factories have been in operation for less than a year, and the kiln car often has problems and needs to be replaced, which not only increases production costs, but also changes the understanding of tunnel kilns, and feels that tunnel kilns are inferior to other kilns. In fact, the root cause is the insulation layer of the kiln car, and the seemingly simple insulation layer problem has not been properly handled.

Some kiln cars did not reduce the thickness and material of the thermal insulation layer, but the thermal insulation effect was still very poor. Why is the temperature under some tunnel kiln cars only 40℃~50℃, people can check it smoothly under the car, while the temperature under some cars is so high that people can't get into the car at all. In fact, the reason is very simple, it is caused by the gap in the insulation layer of the kiln car.

Problems that should be paid attention to in the construction of tunnel kiln

The performance of the tunnel kiln depends not only on the integrity of the design, but also closely related to the construction. The quality of each construction step affects the quality and performance of the tunnel kiln.

1. Construction materials must be guaranteed.

In the design process of the kiln, the material properties and usage requirements of various materials are considered, and the usage position and thickness of the materials are calculated. In order to ensure the construction quality, the use position and amount of materials shall not be arbitrarily changed during the construction process, nor the variety and quality grade of the materials used.

If it is to be replaced, the strength grade of the structural material must be higher than that of the original design material, and the thermal conductivity of the insulation material to be replaced must be lower than that of the original material.

2. Construction according to design requirements.

In the process of using the tunnel kiln, the technical requirements that should be met in the construction process, the construction difficulty and the solutions are fully considered. Many norms and standards are used in the design, including national standards and norms, provincial and ministerial-level standards and norms, local-level standards and norms, and industry standards and norms.

In the construction requirements, specific requirements are put forward for each part. These requirements are in line with the requirements of the construction specifications and standards. If you want to change them, you must refer to the corresponding items of the specifications and standards, and make changes according to the requirements of the specifications and standards. Change.

The materials used in construction are generally those published in national standards. If the specifications and models of the materials are to be changed, the original design materials should be replaced by materials with higher performance in accordance with the national standards.

Problems and lessons in tunnel kiln construction

As we all know, there are three principles to produce good fired bricks: raw materials are the foundation, kiln equipment is the key, and management is the foundation. If it is not designed, the materials used are inferior, and the construction is arbitrarily commissioned, the kiln will become the biggest obstacle to the sustainable development of the production enterprise. There are the following fatal problems in the reconstruction and new construction of tunnel kilns, which should be paid great attention by colleagues in the whole industry:

1. The furnace design is unreasonable

Some enterprises do not pay attention to the process design of sintering kilns. There are generally simple kiln structures, unscientific drying kiln structures, and unreasonable air duct design, so that various tunnel kilns of different lengths appear in front of us. In order to meet the owner's blind request to reduce the cost, many tunnel kilns are overweight and weak.

Whether the tunnel kiln design is reasonable and perfect directly restricts the quality of the kiln. Some investors pay too much attention to investment control and ignore the design and construction of the kiln, resulting in high coal consumption, high cost, high maintenance frequency, A vicious cycle of low reliability and difficult operation.

2. Most construction teams are unqualified, and the construction quality is worrying

It is one of the most prominent problems at present to arbitrarily entrust the construction of units without kiln construction qualifications. They lack necessary job training and qualification certification of construction personnel. The construction quality of most tunnel kilns cannot be guaranteed, the foundation is not strong, and the kiln The body is cracked, the drying effect of the bricks is not good, and the phenomenon of serious collapse and falling of the bricks occurs frequently during the drying process, and the product energy consumption is high and the quality is poor. Quality accidents and quality lawsuits are not uncommon.

Burning bricks requires coal or other fuels. How to maximize the thermal efficiency is the technical key of brick kiln design. The sintering temperature of brick is between 850 ° C and 1050 ° C. In order to save coal, the heat insulation effect of the kiln must be improved. The rotary tunnel kiln is stacked with refractory fiber cotton, which not only reduces the weight of the kiln body, reduces the thermal expansion and contraction stress of the kiln body, but also improves the thermal insulation performance of the kiln body. The kiln temperature is maintained for a long time, and the bricks consumed at one time increase in large area. The internal combustion heat energy can more effectively improve the kiln temperature and save fuel.

In ordinary tunnel kilns, in order to prevent high-temperature flue gas from flowing into the kiln car and burning out the wheels and bearings, it is also necessary to set up a gas source under the kiln car. In the whole heating system, the air supply pressure at the bottom and surface of the vehicle must be kept balanced, and the high temperature flue gas and cold air at the bottom of the vehicle must not rise to reduce the kiln temperature.

 The bricks of the rotary tunnel kiln are directly stacked on the ground, without air supply under the vehicle, and the ground temperature is directly fully utilized. It is found that the aluminum silicate fiber blanket can still be calcined normally after 48 hours of coal and air shutdown in actual production, which is impossible for ordinary tunnel kilns. In the annular rotary tunnel kiln, when the firing temperature of bricks is reduced to room temperature, the heat released is enough to dry wet bricks of the same volume, so there is no need to build a hot air furnace, nor need to use the superheat roasting process to consume more coal to dry the heat.

In the heating system of the annular rotary tunnel kiln, dry air enters from the kiln tail and cools the sintered bricks through the cooling section to reduce the temperature of the sintered bricks at the outlet of the kiln tail to room temperature, that is, all the heat emitted by the sintered bricks is carried to the roasting section and drying section through the air entering the kiln for combustion support and drying. The energy saving of circular rotary tunnel kiln is its remarkable feature. Its reasonable process design, layout and simple logistics route also greatly reduce the energy consumption of the whole brick factory.

The circular rotary tunnel kiln fully adopts mechanized operation and automatic digital control system. The temperature in the kiln is directly displayed on the display screen of the control system. There is no need to hire high-paying fire-watching teachers, which fundamentally eliminates brick-making and greatly increases production.

Compared with the traditional tunnel kiln, the new energy-saving and environment-friendly mobile rotary tunnel kiln has great advantages. It can be predicted that the production mode of the new energy-saving and environment-friendly mobile rotary tunnel kiln will be widely used in the field of sintered bricks by comparing the Helu aluminum silicate fiber blanket.