A system for firing gangue internal combustion bricks by coupling a tunnel kiln with a waste heat boiler

Abstract

The present invention discloses a system for firing coal gangue internal combustion bricks using a tunnel kiln coupled with a waste heat boiler. This system belongs to the field of brick and tile sintering technology and addresses the existing issues of high air consumption, low quality finished bricks, and low waste heat recovery. The system comprises a tunnel kiln and a brick-carrying kiln vehicle that travels within the tunnel kiln. The tunnel kiln is sequentially divided into a tunnel kiln cooling zone, a tunnel kiln firing zone, and a tunnel kiln preheating zone from the kiln tail to the kiln head. The present invention reduces the amount of air required for combustion in the tunnel kiln, lowering the excess air coefficient from the current 6-8 to 2.6-2.8. Multi-point distributed automatic temperature measurement and control devices are installed in the tunnel kiln firing zone to maintain the temperature within the tunnel kiln at the set firing temperature, achieving constant-temperature sintering and ensuring the quality of the finished bricks. Uniformly distributed multi-point waste heat recovery maximizes the recovery of all excess heat within the tunnel kiln.

Description

Technical Field

[0001] The present invention belongs to the technical field of brick and tile sintering, and in particular relates to a system for firing gangue internal combustion bricks by coupling a tunnel kiln with a waste heat boiler. Background Art

[0002] Tunnel kilns are currently the most common method of producing internal combustion bricks made from coal gangue. The gangue in internal combustion bricks serves as both the raw material and the fuel. During the brickmaking process, the bricks are mechanically pressed into shape in a single press, the fuel solidifies within the bricks, and the bricks are then fired in a tunnel kiln.

[0003] When firing internal combustion bricks, the tunnel kiln uses all the air to inhale natural air through the blower and pressurize it to be sent into the tunnel kiln from the tail of the tunnel kiln. The cold air entering the kiln first contacts the finished bricks that are about to be discharged from the kiln after being cooled, and flows to the kiln head through the gaps between the bricks on the kiln cars arranged in sequence in the tunnel kiln. The kiln cars move in the opposite direction of the air flow and move to the kiln tail at regular intervals. In this way, the hot air flow and the high-temperature bricks form reverse convection heat exchange. In the cooling zone of the tunnel kiln, as the bricks move to the cooling zone, the temperature of the bricks is gradually cooled, and the wind temperature gradually increases. When the wind temperature rises to the hot air temperature required by the brick drying kiln, the hot air is extracted from the tunnel kiln in sections and supplied to the brick drying kiln for drying the bricks. The low-temperature air that is not extracted from the tunnel roasting kiln and is necessary for fuel combustion will continue to flow to the kiln head and continue to be heated by the high-temperature bricks until the set sintering temperature is reached. The hot air enters the combustion zone and begins to burn, and the bricks serving as fuel complete the roasting process and enter the cooling stage.

[0004] To achieve sintering, the high-temperature hot air must maintain a relatively constant temperature throughout the firing zone, remaining in a continuous combustion state as it moves toward the kiln head until the brick combustion temperature—the beginning of the firing zone—is reached. To maintain a relatively stable firing zone temperature, a low-temperature flue gas extraction control system is specifically designed at the starting point of the firing zone to regulate the kiln temperature. This extracted low-temperature flue gas is mixed with the dry hot air from the kiln tail and fed to the drying kiln. Due to the long firing zone of the kiln, once the bricks reach the firing temperature, as long as there is sufficient oxygen, they will combust, releasing heat continuously and gradually increasing the temperature within the tunnel kiln. To ensure that the bricks are sintered at the set temperature in the firing section, the combustion temperature must be kept stable throughout the firing zone. The key to controlling product quality and production capacity in tunnel-type brick and tile kilns lies in the ability to systematically control the firing zone to maintain a constant temperature under continuous and stable combustion conditions.

[0005] The following methods are currently used: First, a large amount of low-temperature hot air is extracted at the beginning of the cooling zone (the end of the firing zone) to reduce the temperature and reduce the amount of air in the kiln; second, low-temperature flue gas is extracted at the beginning of the firing zone (the end of the preheating zone) to increase the amount of air in the kiln. Multiple temperature measurement points are set between the two end points to control the maximum temperature not to exceed the set value. Figure 2shown.

[0006] In actual operation, once the bricks enter the firing tunnel kiln from the kiln head and are heated to the combustion temperature by the high-temperature flue gas, as long as the oxygen supply in the kiln is maintained, combustion will continue, the heat in the fuel will continue to be released, and the temperature in the kiln will gradually increase. When the temperature in the middle of the firing zone rises to the set temperature, the amount of new air entering the kiln must be reduced, the oxygen supply to the fuel will be reduced, the combustion intensity will be reduced, and the temperature in the kiln will drop. On the contrary, if the amount of new air entering the tunnel kiln is increased, the combustion intensity will be strengthened, and the temperature in the kiln will rise. The regulating effect of the low-temperature flue gas at the starting end of the firing zone must ensure that the high-temperature flue gas reaching the head of the tunnel kiln can meet the needs of heating the cold bricks entering the kiln to the firing temperature in the preheating zone, and finally be extracted by the kiln head induced draft fan and discharged after flue gas treatment. The key control link for sintering internal combustion bricks in the entire brick and tile tunnel firing kiln is how to keep the bricks burning stably throughout the firing zone and keep the temperature unchanged. Summary of the Invention

[0007] The purpose of the present invention is to address the deficiencies in the prior art and provide a system for firing gangue internal combustion bricks by coupling a tunnel kiln with a waste heat boiler, which has low air consumption, high quality of finished bricks and high waste heat recovery rate.

[0008] In order to achieve the above technical objectives, the technical solution adopted by the system of firing gangue internal combustion bricks by coupling a tunnel kiln with a waste heat boiler of the present invention is as follows:

[0009] A system for firing coal gangue internal combustion bricks by coupling a tunnel kiln with a waste heat boiler, comprising a tunnel kiln and a brick transporting kiln vehicle running in the tunnel kiln;

[0010] The tunnel roasting kiln is distributed from the kiln tail to the kiln head in sequence as a tunnel kiln cooling zone, a tunnel kiln firing zone and a tunnel kiln preheating zone;

[0011] A blower is provided above the cooling zone of the tunnel kiln, and an air supply main is connected to the air supply main at its outlet. A plurality of air supply branches extending into the rear section of the cooling zone of the tunnel kiln are connected in parallel to the air supply main. An exhaust main is provided above the front section of the cooling zone of the tunnel kiln, and a plurality of exhaust branches extending into the front section of the cooling zone of the tunnel kiln are connected in parallel to the exhaust main.

[0012] A first waste heat boiler and a second waste heat boiler are arranged adjacently above the tunnel kiln firing zone. An air preheater is provided at the upper end of the first waste heat boiler and a first high-temperature flue gas header is provided at the lower end. A supplementary fan is connected to the side of the air preheater via a pipe A. A pipe B connected to the side of the air preheater is provided below the pipe A. The port of the pipe B is connected to the main pipe A. The main pipe A is connected in parallel with a plurality of branch pipes A extending into the rear section of the tunnel kiln firing zone. A plurality of branch pipes B extending into the rear section of the tunnel kiln firing zone are provided at the bottom of the first high-temperature flue gas header. The top of the heat exchanger is connected to the first induced draft fan via pipe C. The air outlet of the first induced draft fan is connected to pipe D. The end of pipe D is connected to main pipe B. Multiple branch pipes C are connected in parallel to main pipe B and extend into the front section of the firing zone of the tunnel kiln. A second high-temperature flue gas header is provided at the bottom of the second waste heat boiler. Multiple branch pipes D are provided at the bottom of the second high-temperature flue gas header and extend into the front section of the firing zone of the tunnel kiln. The upper part of the second waste heat boiler is connected to the second induced draft fan via pipe E. The air outlet of the second induced draft fan is connected to pipe F. The end of pipe F is connected to the manifold.

[0013] A third induced draft fan is provided above the preheating zone of the tunnel kiln. The air inlet of the third induced draft fan is connected to the main pipe C. The main pipe C is connected in parallel with a plurality of branch pipes E extending into the front section of the preheating zone of the tunnel kiln. The air outlet of the third induced draft fan is connected to the pipe G. The pipe G and the pipe F are connected to the collecting pipe after merging.

[0014] Preferably, the air flow direction in the tunnel roasting kiln is opposite to the travel direction of the brick kiln vehicle.

[0015] Preferably, the exhaust pipe is connected to the low temperature drying kiln pipeline

[0016] Preferably, the collecting pipe is connected to the high-temperature drying kiln pipeline.

[0017] Preferably, the branch pipe A and the branch pipe B are evenly distributed in the rear section of the tunnel kiln firing zone.

[0018] Preferably, the branch pipe C and the branch pipe D are evenly distributed in the front section of the tunnel kiln firing zone.

[0019] Preferably, the duct F is provided with a second induced draft fan regulating door for regulating the air output of the second induced draft fan.

[0020] Preferably, the duct G is provided with a third induced draft fan regulating door for regulating the air output of the third induced draft fan.

[0021] A system for firing gangue internal combustion bricks by coupling a tunnel kiln with a waste heat boiler comprises the following steps:

[0022] (1) Bricks are produced through the brick production line and placed on the kiln car;

[0023] (2) sending the kiln car into the tunnel roasting kiln and passing it through the tunnel kiln preheating zone, tunnel kiln firing zone and tunnel kiln cooling zone in sequence;

[0024] (3) The blower sucks in natural air and pressurizes it, and then sends it into the tunnel roasting kiln from multiple air supply branches at multiple points. The cold air entering the kiln flows through the gaps between the gradually cooling bricks toward the kiln head, forming convection heat exchange with the bricks. The high-temperature bricks gradually cool down, and the air temperature rises to the temperature used for drying kiln heat. A large amount of low-temperature hot air is extracted from multiple points in the front section of the tunnel kiln cooling zone through the exhaust branch pipe and merged into the low-temperature drying kiln pipeline;

[0025] (4) The remaining low-temperature hot air in the cooling zone of the tunnel kiln continues to flow toward the kiln head, the temperature of the bricks gradually decreases, and the air temperature rises to the baking constant temperature value set in the firing zone of the tunnel kiln. During this process, the supplementary fan inhales and pressurizes the cold air, and sends it to the air preheater of the first waste heat boiler to be preheated to the required temperature, and then enters the tunnel kiln through the branch pipe A to mix with the high-temperature flue gas in the kiln. The mixed high-temperature flue gas is based on the set baking temperature. After each mixing period, the same amount of high-temperature flue gas mixed in this section is extracted into the first high-temperature flue gas header, enters the first waste heat boiler to cool down and then is discharged, and then is extracted and pressurized by the first induced draft fan, and enters the tunnel kiln through the branch pipe C to mix with the high-temperature flue gas in the kiln. After each mixing period, the same amount of high-temperature flue gas mixed in this section is extracted into the second high-temperature flue gas header, enters the second waste heat boiler to cool down and then is discharged, and then is extracted and pressurized by the second induced draft fan and collected in the collection pipe;

[0026] (5) The third induced draft fan arranged at the head of the tunnel kiln extracts the preheated flue gas from the head of the tunnel kiln and pressurizes it, collects it in the collecting pipe, and then flows into the high-temperature drying kiln pipeline.

[0027] Compared with the prior art, the present invention has the following beneficial effects:

[0028] (1) The present invention reduces the amount of air required for combustion in the tunnel kiln, and the excess air coefficient can be reduced from the current 6 to 8 to 2.6 to 2.8, thereby reducing the new air consumption for sintering bricks in the tunnel kiln and lowering the investment and operating costs for flue gas pollutant treatment;

[0029] (2) A multi-point distributed automatic temperature control device is set in the firing zone of the tunnel kiln, which can keep the temperature in the tunnel kiln at the set firing temperature at all times, realize constant temperature sintering, eliminate under-firing, over-firing and fluidization, and ensure the quality of the finished bricks;

[0030] (3) In the whole tunnel kiln firing zone, the hot air flow rate is kept relatively stable in the cross section of the tunnel kiln, so that the ventilation resistance of the whole tunnel kiln firing zone is reduced, the power consumption of the induced draft fan is reduced, and the flue gas in the zone is always in a state of longitudinal steady flow and transverse turbulence, which ensures the full combustion of the fuel, shortens the combustion time, and makes it easy to ensure the sintering strength of the bricks, thereby improving the production capacity of the tunnel kiln;

[0031] (4) The waste heat boiler coupled with the present invention adopts a uniformly distributed multi-point waste heat recovery method, which can recover all the excess heat in the tunnel kiln to the maximum extent. Since the entire firing zone is always in a fully burned state, it can ensure the stability of temperature, steam temperature and pressure, greatly improve the waste heat recovery rate, and improve the economic benefits of waste heat power generation. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 It is the temperature change curve in the tunnel roasting kiln;

[0033] Figure 2 This is the working principle diagram of the current tunnel roasting kiln to maintain a constant combustion temperature;

[0034] Figure 3 This is a working principle diagram of the tunnel roasting kiln coupled with the waste heat boiler of the present invention.

[0035] In the figure: 1. Tunnel roasting kiln; 2. Brick kiln transport car; 3. Supply fan; 4. Supply air main; 5. Supply air branch; 6. Exhaust air main; 7. Exhaust air branch; 8. First waste heat boiler; 9. Second waste heat boiler; 10. Air preheater; 11. First high-temperature flue gas header; 12. Pipe A; 13. Supplementary fan; 14. Pipe B; 15. Main pipe A; 16. Branch pipe A; 17. Branch pipe B; 18. Pipe C; 19. First induced draft fan; 20. Pipe D; 21. Main pipe B; 22. Branch pipe C; 23. Second high-temperature flue gas header; 24. Branch pipe D; 25. Pipe E; 26. Second induced draft fan; 27. Pipe F; 28. Manifold; 29. ​​Third induced draft fan; 30. Main pipe; 31. Branch pipe E; 32. Pipe G; 33. Second induced draft fan regulating door; 34. Third induced draft fan regulating door

[0036] 101. Tunnel kiln cooling zone; 102. Tunnel kiln firing zone; 103. Tunnel kiln preheating zone. DETAILED DESCRIPTION

[0037] The present invention will be further described below with reference to the accompanying drawings and specific embodiments:

[0038] The temperature of the existing tunnel kiln firing zone is only regulated by exhaust at the kiln tail and kiln head. However, there is no quantitative control measure during the tunnel kiln firing process, which makes it impossible to ensure that the firing temperature of the entire firing zone remains constant. As a result, the bricks often become under-fired or over-fired during the firing process, which directly affects the quality of the fired bricks.

[0039] Relying solely on the flue gas extracted from the kiln head and the low-temperature hot air extracted from the kiln tail to meet the heat required for tunnel kiln drying cannot ensure that the heat required for drying is balanced with the heat extracted from the roasting kiln. In order to ensure the heat required for drying the bricks, the calorific value of the bricks is artificially increased when making the brick ingredients, so that the total heat in the bricks is greater than the actual heat required for sintering bricks. Therefore, it is impossible to fully recover the excess heat released by the bricks during the tunnel kiln roasting process, resulting in a waste of some heat energy.

[0040] According to the requirements of the internal combustion brick sintering process, the present invention first controls the total amount of basic combustion air and high-temperature drying air entering the kiln from the kiln tail, which is conducive to the rapid heating of the cold air entering the kiln in the cooling zone of the tunnel kiln. After reaching the set combustion temperature, the tunnel kiln firing zone is evenly divided into several sections. According to the changes in the combustion temperature in the kiln, part of the low-temperature combustion air is added to each section respectively, which not only neutralizes the heat released by the combustion in this section and keeps the temperature of this section unchanged in a continuous combustion state, but also when the flue gas in this section flows downstream, the excess high-temperature flue gas formed by the neutralization of the heat released by the combustion is extracted out of the tunnel kiln, and the flue gas flow rate in the entire tunnel kiln is kept stable. The high-temperature flue gas extracted out of the kiln is recycled and utilized as a heat source for the waste heat boiler coupled to the tunnel kiln. In this way, not only can the temperature stability of the firing zone be effectively controlled, but also the combustion conditions can be greatly improved, the combustion time can be shortened, and the production capacity can be increased. At the same time, all the excess heat of the tunnel kiln can be effectively recycled and utilized.

[0041] like Figure 3 As shown, the present invention provides a system for firing coal gangue internal combustion bricks by coupling a tunnel kiln with a waste heat boiler, comprising a tunnel roasting kiln 1 and a brick transporting kiln vehicle 2 running in the tunnel roasting kiln 1;

[0042] The tunnel roasting kiln 1 is distributed from the kiln tail to the kiln head in sequence as a tunnel kiln cooling zone 101, a tunnel kiln firing zone 102 and a tunnel kiln preheating zone 103;

[0043] A blower 3 is provided above the tunnel kiln cooling zone 101, and an air supply main pipe 4 is connected to the air outlet of the blower 3. A plurality of air supply branch pipes 5 extending into the rear section of the tunnel kiln cooling zone 101 are connected in parallel to the air supply main pipe 4. An exhaust main pipe 6 is provided above the front section of the tunnel kiln cooling zone 101. The exhaust main pipe 6 is connected to the low-temperature drying kiln pipeline, and a plurality of exhaust branch pipes 7 extending into the front section of the tunnel kiln cooling zone 101 are connected in parallel to the exhaust main pipe 6.

[0044] A first waste heat boiler 8 and a second waste heat boiler 9 are arranged adjacently above the tunnel kiln firing zone 102. An air preheater 10 is provided at the upper end of the first waste heat boiler 8, and a first high-temperature flue gas header 11 is provided at the lower end. The side of the air preheater 10 is connected to a supplementary fan 13 via a pipe A12. A pipe B14 connected to the side of the air preheater 10 is provided below the pipe A12. The port of the pipe B14 is connected to the main pipe A15. The main pipe A15 is connected in parallel with a plurality of branch pipes A16 extending into the rear section of the tunnel kiln firing zone 102. A plurality of branch pipes B17 extending into the rear section of the tunnel kiln firing zone 102 are provided at the bottom of the first high-temperature flue gas header 11. The top of the air preheater 10 is connected to the first induced draft fan 1 via a pipe C18. 9 is connected, the air outlet of the first induced draft fan 19 is connected to the pipe D20, the port of the pipe D20 is connected to the main pipe B21, and the main pipe B21 is connected in parallel with multiple branch pipes C22 extending into the front section of the tunnel kiln firing zone 102. The bottom of the second waste heat boiler 9 is provided with a second high-temperature flue gas header 23, and the bottom of the second high-temperature flue gas header 23 is provided with multiple branch pipes D24 extending into the front section of the tunnel kiln firing zone 102. The upper part of the second waste heat boiler 9 is connected to the second induced draft fan 26 through the pipe E25, and the air outlet of the second induced draft fan 26 is connected to the pipe F27. The pipe F27 is provided with a second induced draft fan regulating door 33 for adjusting the air output of the second induced draft fan 26. The port of the pipe F27 is connected to the collecting pipe 28;

[0045] A third induced draft fan 29 is provided above the tunnel kiln preheating zone 103. The air inlet of the third induced draft fan 29 is connected to the main pipe C30. The main pipe C30 is connected in parallel with multiple branch pipes E31 extending into the front section of the tunnel kiln preheating zone 103. The air outlet of the third induced draft fan 29 is connected to the pipe G32. The pipe G32 is provided with a third induced draft fan regulating door 34 for regulating the air output of the third induced draft fan 29. The pipe G32 and the pipe F27 are merged and connected to the collecting pipe 28. The collecting pipe 28 is connected to the high-temperature drying kiln pipe.

[0046] The present invention controls the amount of air entering the tunnel roasting kiln according to the combustion conditions, reduces the new air consumption in the tunnel kiln, and reduces the air pollution in the tunnel kiln; according to the heat consumption of low-temperature drying, the temperature and flow dual elements are used to control the extraction amount of low-temperature drying hot air in the rear half of the tunnel kiln cooling zone; a low-temperature supplementary combustion hot air inlet is set in the rear half of the tunnel kiln firing zone, and the supplementary combustion air of each section is automatically adjusted based on the kiln temperature after mixing in the section (i.e. the set temperature of the firing zone); then the high-temperature hot air mixed in the kiln by each section of supplementary combustion is extracted out of the kiln respectively, and the mixed hot air is collected as the first residual air. Heat source of heat boiler; the high-temperature hot air extracted from the kiln is cooled to an appropriate temperature by the heat exchange components of the first waste heat boiler, and then used as the low-temperature balanced supplementary combustion hot air (with reduced oxygen content) in each section of the front half of the tunnel kiln firing zone. The supplementary combustion air in each section of the front half uses the kiln temperature after mixing in that section (still based on the set temperature of the firing zone) as the control benchmark, and automatically adjusts the air intake; the high-temperature flue gas extracted from each section of the front half of the tunnel kiln firing zone is then collected as the heat source of the second waste heat boiler, and after being cooled to the temperature required by the high-temperature drying kiln by the heat exchange components of the second waste heat boiler, it is sent to the high-temperature drying kiln for use.

[0047] In the present invention, both the first waste heat boiler and the second waste heat boiler use the high-temperature flue gas set by the tunnel roasting kiln as the heat source, which is convenient for stable utilization and has a low flow rate. In order to improve the efficiency of waste heat power generation, the present invention adopts a high-temperature medium-pressure steam parameter waste heat boiler to achieve gradient utilization of thermal energy and ensure that all sintering waste heat is recovered and utilized. Under the same condition of the low calorific value of internal combustion bricks, the power generation capacity can be more than doubled than that of the existing cooling belt radiation waste heat boiler.

[0048] The present invention not only ensures that the bricks used as fuel in the tunnel kiln firing zone are always in a disturbed combustion state, thereby improving the combustion intensity and saving the combustion time, but also improves the production capacity of the tunnel roasting kiln and ensures the temperature of the entire firing zone is stable.

[0049] After the high-temperature flue gas in the front section of the tunnel kiln firing zone of the present invention is extracted, the high-temperature flue gas remaining in the tunnel kiln is controlled in an orderly manner to ensure that the cold bricks entering the tunnel kiln are heated to the firing temperature and then mixed with the flue gas discharged from the flue gas waste heat boiler, so as to meet the flue gas volume and temperature requirements required for high-temperature drying of the hot flue gas. Among them, the principle of tunnel kiln roasting is to always control the temperature in the kiln. The recovered heat depends on the heat content of the internal combustion bricks themselves. In addition to the heat used by the roasting kiln itself, all excess heat can be recycled and utilized to make the best use of it.

[0050] Branch pipes A16 and B17 are evenly distributed in the rear section of the tunnel kiln firing zone 102, while branch pipes C22 and D24 are evenly distributed in the front section of the tunnel kiln firing zone 102. Aligning branch pipes A16 and B17, and branch pipes C22 and D24, allows flue gas input and extraction to occur in the same section, ensuring temperature uniformity.

[0051] A system for firing gangue internal combustion bricks by coupling a tunnel kiln with a waste heat boiler comprises the following steps:

[0052] (1) Bricks are produced through the brick production line and placed on the kiln car;

[0053] (2) sending the kiln car into the tunnel roasting kiln and passing it through the tunnel kiln preheating zone, tunnel kiln firing zone and tunnel kiln cooling zone in sequence;

[0054] (3) The blower sucks in natural air and pressurizes it, and then sends it into the tunnel roasting kiln from multiple air supply branches at multiple points. The cold air entering the kiln flows through the gaps between the gradually cooling bricks toward the kiln head, forming convection heat exchange with the bricks. The high-temperature bricks gradually cool down, and the air temperature rises to the temperature used for drying kiln heat. A large amount of low-temperature hot air is extracted from multiple points in the front section of the tunnel kiln cooling zone through the exhaust branch pipe and merged into the low-temperature drying kiln pipeline;

[0055] (4) The remaining low-temperature hot air in the cooling zone of the tunnel kiln continues to flow toward the kiln head, the temperature of the bricks gradually decreases, and the air temperature rises to the baking constant temperature value set in the firing zone of the tunnel kiln. During this process, the supplementary fan inhales and pressurizes the cold air, and sends it to the air preheater of the first waste heat boiler to be preheated to the required temperature, and enters the tunnel kiln through the branch pipe A to mix with the high-temperature flue gas in the kiln. The mixed high-temperature flue gas is based on the set baking temperature. After each mixing period, the same amount of high-temperature flue gas mixed in this section is extracted into the first high-temperature flue gas header, enters the first waste heat boiler to cool down and then is discharged, and then is extracted and pressurized by the first induced draft fan, and enters the tunnel kiln through the branch pipe C to mix with the high-temperature flue gas in the kiln. After each mixing period, the same amount of high-temperature flue gas mixed in this section is extracted into the second high-temperature flue gas header, enters the second waste heat boiler to cool down and then is discharged, and then is extracted and pressurized by the second induced draft fan and collected in the collection pipe;

[0056] (5) The third induced draft fan arranged at the head of the tunnel kiln extracts the preheated flue gas from the head of the tunnel kiln and pressurizes it, collects it in the collecting pipe, and then flows into the high-temperature drying kiln pipeline.

[0057] In summary, the above are only preferred embodiments of the present invention and are not intended to limit the scope of implementation of the present invention. All equivalent changes and modifications in the shape, structure, characteristics and spirit of the claims of the present invention should be included in the scope of the claims of the present invention.

Claims

1. A system for firing coal gangue internal combustion bricks using a tunnel kiln coupled with a waste heat boiler, comprising a tunnel kiln and a kiln vehicle for transporting bricks that travels within the tunnel kiln. The tunnel roasting kiln is distributed from the kiln tail to the kiln head in sequence as a tunnel kiln cooling zone, a tunnel kiln firing zone and a tunnel kiln preheating zone; Its characteristics are: A blower is provided above the cooling zone of the tunnel kiln, and an air supply main is connected to the air supply main at its outlet. A plurality of air supply branches extending into the rear section of the cooling zone of the tunnel kiln are connected in parallel to the air supply main. An exhaust main is provided above the front section of the cooling zone of the tunnel kiln, and a plurality of exhaust branches extending into the front section of the cooling zone of the tunnel kiln are connected in parallel to the exhaust main. A first waste heat boiler and a second waste heat boiler are arranged adjacently above the tunnel kiln firing zone. An air preheater is provided at the upper end of the first waste heat boiler and a first high-temperature flue gas header is provided at the lower end. A supplementary fan is connected to the side of the air preheater via a pipe A. A pipe B connected to the side of the air preheater is provided below the pipe A. The port of the pipe B is connected to the main pipe A. The main pipe A is connected in parallel with a plurality of branch pipes A extending into the rear section of the tunnel kiln firing zone. A plurality of branch pipes B extending into the rear section of the tunnel kiln firing zone are provided at the bottom of the first high-temperature flue gas header. The top of the heat exchanger is connected to the first induced draft fan via pipe C. The air outlet of the first induced draft fan is connected to pipe D. The end of pipe D is connected to main pipe B. Multiple branch pipes C are connected in parallel to main pipe B and extend into the front section of the firing zone of the tunnel kiln. A second high-temperature flue gas header is provided at the bottom of the second waste heat boiler. Multiple branch pipes D are provided at the bottom of the second high-temperature flue gas header and extend into the front section of the firing zone of the tunnel kiln. The upper part of the second waste heat boiler is connected to the second induced draft fan via pipe E. The air outlet of the second induced draft fan is connected to pipe F. The end of pipe F is connected to the manifold. A third induced draft fan is provided above the preheating zone of the tunnel kiln. The air inlet of the third induced draft fan is connected to the main pipe C. The main pipe C is connected in parallel with a plurality of branch pipes E extending into the front section of the preheating zone of the tunnel kiln. The air outlet of the third induced draft fan is connected to the pipe G. The pipe G and the pipe F are connected to the collecting pipe after merging.

2. The system for firing gangue internal combustion bricks by coupling a tunnel kiln with a waste heat boiler according to claim 1 is characterized in that: The air flow direction in the tunnel roasting kiln is opposite to the driving direction of the brick kiln vehicle.

3. The system for firing gangue internal combustion bricks by coupling a tunnel kiln with a waste heat boiler according to claim 1 is characterized in that: The exhaust main pipe is connected to the low-temperature drying kiln pipeline.

4. The system for firing gangue internal combustion bricks by coupling a tunnel kiln with a waste heat boiler according to claim 1 is characterized in that: The collecting pipe is connected with the high-temperature drying kiln pipeline.

5. The system for firing gangue internal combustion bricks by coupling a tunnel kiln with a waste heat boiler according to claim 1 is characterized in that: The branch pipe A and the branch pipe B are evenly distributed in the rear section of the tunnel kiln firing zone.

6. The system for firing gangue internal combustion bricks by coupling a tunnel kiln with a waste heat boiler according to claim 1 is characterized in that: The branch pipes C and D are correspondingly and evenly distributed in the front section of the firing zone of the tunnel kiln.

7. The system for firing gangue internal combustion bricks by coupling a tunnel kiln with a waste heat boiler according to claim 1 is characterized in that: The duct F is provided with a second induced draft fan regulating door for regulating the air output of the second induced draft fan.

8. The system for firing gangue internal combustion bricks by coupling a tunnel kiln with a waste heat boiler according to claim 1 is characterized in that: The duct G is provided with a third induced draft fan regulating door for regulating the air output of the third induced draft fan.

9. The system for firing gangue internal combustion bricks by coupling a tunnel kiln with a waste heat boiler according to claim 1 is characterized in that: The following steps are involved: (1) Bricks are produced through the brick production line and placed on the kiln car; (2) sending the kiln car into the tunnel roasting kiln and passing it through the tunnel kiln preheating zone, tunnel kiln firing zone and tunnel kiln cooling zone in sequence; (3) The blower sucks in natural air and pressurizes it, and then sends it into the tunnel roasting kiln from multiple air supply branches at multiple points. The cold air entering the kiln flows through the gaps between the gradually cooling bricks toward the kiln head, forming convection heat exchange with the bricks. The high-temperature bricks gradually cool down, and the air temperature rises to the temperature used for drying kiln heat. A large amount of low-temperature hot air is extracted from multiple points in the front section of the tunnel kiln cooling zone through the exhaust branch pipe and merged into the low-temperature drying kiln pipeline; (4) The remaining low-temperature hot air in the cooling zone of the tunnel kiln continues to flow toward the kiln head, the temperature of the bricks gradually decreases, and the air temperature rises to the baking constant temperature value set in the firing zone of the tunnel kiln. During this process, the supplementary fan inhales and pressurizes the cold air, and sends it to the air preheater of the first waste heat boiler to be preheated to the required temperature, and enters the tunnel kiln through the branch pipe A to mix with the high-temperature flue gas in the kiln. The mixed high-temperature flue gas is based on the set baking temperature. After each mixing period, the same amount of high-temperature flue gas mixed in this section is extracted into the first high-temperature flue gas header, enters the first waste heat boiler to cool down and then is discharged, and then is extracted and pressurized by the first induced draft fan, and enters the tunnel kiln through the branch pipe C to mix with the high-temperature flue gas in the kiln. After each mixing period, the same amount of high-temperature flue gas mixed in this section is extracted into the second high-temperature flue gas header, enters the second waste heat boiler to cool down and then is discharged, and then is extracted and pressurized by the second induced draft fan and collected in the collection pipe; (5) The third induced draft fan arranged at the head of the tunnel kiln extracts the preheated flue gas from the head of the tunnel kiln and pressurizes it, collects it in the collecting pipe, and then flows into the high-temperature drying kiln pipeline.

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