Sinter cooling waste gas waste heat cascade utilization system and use method

Abstract

The present application relates to a kind of sinter cooling waste gas waste heat cascade utilization system and use method, including ring cooling machine, sealed upper cover, wind box and waste gas circulation system, waste gas circulation system includes waste heat boiler, regulating valve and diffusion valve, normal production state, all accident diffusion valves are in closed state, the waste gas of upper cover section and upper cover second section is imported into waste heat boiler, after heat exchange by regenerative fan I is sent into back wind second section wind box and back wind third section wind box;When waste heat boiler import wind temperature is high, waste heat boiler import wind temperature is adjusted by regulating valve and accident diffusion valve;The waste gas of upper cover third section is sent into sintering machine material surface or back wind first section wind box, the waste gas of upper cover fourth section is sent into back wind first section wind box or is discharged after purification by dust removal system, the waste gas of upper cover fifth section is sent into back wind fourth section wind box by regenerative fan IV.Its advantages are: effectively improve the utilization rate and the stability of operation of waste heat boiler;Increase the proportion of waste gas self-circulation, realize ring cooling machine waste gas zero emission.

Description

Technical Field

[0001] This invention belongs to the technical field of waste heat recovery and utilization systems for waste gas from an annular cooler, and in particular relates to a cascade utilization system for waste heat from sintered ore cooling waste gas. Background Technology

[0002] Sintering has always been one of the most polluting processes in steel enterprises. In recent years, the rapid development of end-of-pipe treatment technologies has improved the control of particulate matter, sulfur dioxide, and nitrogen oxides emitted by sintering plants to a certain extent. However, the problem of fugitive emissions of dust-laden hot waste gas still exists in the sinter cooling process. Currently, some sintering plants have adopted a new type of blower-type ring cooler (referred to as a ring cooler) to cool hot sinter, which has significantly reduced the air leakage rate of the cooling equipment and basically avoided pollution caused by dust carried by leaks, resulting in a significant improvement in the working environment.

[0003] However, apart from recycling the hot exhaust gas from the front of the annular cooler after heat exchange in a boiler, the remaining hot exhaust gas typically diffuses into the surrounding environment through fugitive emissions. The waste heat of this exhaust gas is not utilized, and the particulate matter it carries is not treated. Some companies collect the dust-laden exhaust gas from the middle and later stages of the annular cooler and purify it through high-efficiency dust collectors before discharging it, significantly increasing the initial investment and operating costs of the environmental dust removal system. To alleviate this problem, a practice has emerged of using the exhaust gas from the later stages as cooling air, using the exhaust gas from the middle stages for hot air sintering, and utilizing the sintering machine to dispose of the annular cooler exhaust gas. Although existing technologies can largely solve the problem of fugitive emissions from annular cooler exhaust gas, the following issues still exist:

[0004] 1) Generally, the air box of the annular cooler is divided into sections according to the working range of the cooling fan. Each blower corresponds to a cooling section. The upper cover section of the annular cooler basically corresponds to the air box section. The heat collection section of the waste heat boiler is the first two sections of the annular cooler, and its area generally accounts for about 40% of the total area of ​​the annular cooler. The exhaust gas taken out from the upper cover of the first two sections of the annular cooler is sent back to the air box of the first two sections of the annular cooler as cooling air after heat exchange in the boiler. This part of the exhaust gas is self-circulated in the first two sections of the annular cooler. Due to the segmentation, the heat collection area of ​​the waste heat boiler is relatively fixed. A large amount of low-temperature exhaust gas waste heat in the middle and rear sections of the annular cooler cannot be recovered by the waste heat boiler.

[0005] 2) Due to the segmented design of the annular cooler's air box and upper shroud, the heat extraction range of the waste heat boiler is basically fixed. When sintering production fluctuates, the temperature of the hot waste gas in front of the annular cooler will also fluctuate. Once the boiler inlet air temperature deviates from the normal operating range, it will affect the working status of the waste heat boiler and may even cause the turbine of the waste heat power generation system to shut down. In actual production, the inlet air temperature of the waste heat boiler is generally adjusted by adjusting the air volume of the corresponding regenerative fan or by adding cold air. This adjustment method is difficult. When the above adjustment methods are ineffective, it is necessary to adjust the sintering production operation to ensure the inlet air temperature of the waste heat boiler, resulting in a situation where sintering production serves waste heat recovery but is not the primary function.

[0006] 3) Under current technological conditions, even after cascade utilization, the annular cooler still needs to discharge a large amount of exhaust gas. If the sintering machine is to be used to completely absorb the exhaust gas discharged from the annular cooler, a very long hood needs to be installed above the material surface of the sintering machine to absorb this part of the exhaust gas using a large proportion of the sintering area. When the sintering flue gas recirculation technology is adopted, a certain proportion of the sintering area also needs to be used to absorb the recirculated flue gas, which will compress the space for absorbing the exhaust gas from the annular cooler through the sintering machine. This presents a problem of "you can't have your cake and eat it too", making it impossible to completely eliminate the fugitive emission source of the annular cooler and achieve zero emissions of exhaust gas from the annular cooler.

[0007] In order to make fuller use of the waste heat from the sintering ore cooling exhaust gas, improve the utilization rate and stability of the waste heat boiler, and completely eliminate the fugitive emission source of the annular cooler, it is necessary to optimize and adjust the exhaust gas circulation system of the annular cooler. Summary of the Invention

[0008] The purpose of this invention is to provide a cascaded utilization system for waste heat from sintered ore cooling exhaust gas. This system breaks away from the conventional approach of corresponding wind box and upper hood sections, planning the wind box and upper hood sections separately. This allows the upper hood section to be unrestricted by the fan's operating range, segmenting the exhaust gas by temperature for cascaded utilization. By expanding the boiler's heat extraction range, the utilization rate of the waste heat boiler is improved; by adding wind temperature control methods, the operational stability of the waste heat boiler is enhanced; and by increasing the proportion of exhaust gas self-recirculation, more favorable conditions are created for achieving zero emissions from the annular cooler exhaust gas.

[0009] The objective of this invention is achieved through the following technical solution:

[0010] This invention discloses a cascade utilization system for waste heat from sintered ore cooling exhaust gas, comprising a ring cooler, a sealed upper cover disposed on the upper part of the ring cooler, a wind box disposed on the lower part of the ring cooler, and a waste gas circulation system. The sealed upper cover, along the material advance direction, consists of five sections in sequence: upper cover section 1, upper cover section 2, upper cover section 3, upper cover section 4, and upper cover section 5. The wind box consists of a return air section 1, a return air section 2, a return air section 3, a return air section 4, and a normal temperature cooling wind box. The waste gas circulation system includes a waste heat boiler, a regenerative fan, a three-way pipe, a regulating valve, and a venting valve. Its distinguishing feature is:

[0011] The first section of the upper cover is connected to the waste heat boiler via exhaust gas pipe A and regulating valve A. The second section of the upper cover is connected to the waste heat boiler via exhaust gas pipe B and regulating valve B. The waste heat boiler is connected to the inlet of the regenerative air fan I. The outlet of the regenerative air fan I is connected to the second and third return air boxes via regulating valves C and D, respectively.

[0012] The upper cover section 3 is connected to the inlet of regenerating air fan II via exhaust gas pipe C. Regenerating air fan II supplies hot air to the sintering machine material surface via pipeline for hot air sintering. The upper cover section 4 is connected to the inlet of regenerating air fan III via exhaust gas pipe D, regulating valve E, and three-way pipe I. The outlet of regenerating air fan III is connected to the first stage return air box. The upper cover section 5 is connected to the inlet of regenerating air fan IV via exhaust gas pipe E, regulating valve F, and three-way pipe II. The outlet of regenerating air fan IV is connected to the fourth stage return air box via pipeline.

[0013] The ambient temperature cooling box is connected to the outlet of the ambient temperature cooling fan.

[0014] Preferably, an emergency vent valve A is provided on the exhaust gas pipe A of the first section of the upper cover, an emergency vent valve B is provided on the exhaust gas pipe B of the second section of the upper cover, an emergency vent valve C is provided on the exhaust gas pipe D of the fourth section of the upper cover, and an emergency vent valve D is provided on the exhaust gas pipe E of the fifth section of the upper cover.

[0015] Preferably, the three-way pipe I and the three-way pipe II are connected to the atmosphere through regulating valve G and regulating valve H, respectively.

[0016] Preferably, the three sections of the upper cover are connected to the inlet of the regenerating fan III via exhaust gas pipe C, regulating valve E, and three-way pipe I, and the outlet of the regenerating fan III is connected to the return air section 1 air box. The four sections of the upper cover are connected to the inlet of the dust removal system via exhaust gas pipe D.

[0017] A method for using a cascade utilization system for waste heat from sintered ore cooling exhaust gas according to the present invention: characterized in that,

[0018] 1) Under normal production conditions, all emergency vent valves are closed. The exhaust gas temperature from the first stage of the upper cover of the annular cooler is about 400°C, and the exhaust gas temperature from the second stage of the upper cover of the annular cooler is about 300°C. The two exhaust gases enter the waste heat boiler through exhaust gas pipe A and exhaust gas pipe B respectively. After heat exchange and mixing in the waste heat boiler, the two exhaust gases are used as cooling air and sent into the return air second stage air box and return air third stage air box by the regenerating air fan I.

[0019] 2) When the inlet air temperature of the waste heat boiler is too high, open the regulating valve A or regulating valve B. If the inlet air temperature of the waste heat boiler is still too high when regulating valve A or regulating valve B is fully open, open the corresponding emergency vent valve A or emergency vent valve B to draw in a certain amount of ambient air to regulate the inlet air temperature of the waste heat boiler.

[0020] 3) The exhaust gas with a temperature of 200℃~250℃ in the three sections of the upper cover is sent to the material surface of the sintering machine through the regenerating blower II for hot air sintering;

[0021] 4) The exhaust gas with a temperature of about 150℃~180℃ in the fourth section of the upper cover is sent into the return air box of the first section by the regenerating fan III as cooling air; when the exhaust gas temperature in the fourth section of the upper cover is higher than 150℃, the ratio of exhaust gas from the fourth section of the upper cover to ambient air is controlled by adjusting the opening of the regulating valve G upstream of the three-way pipe I, so as to control the outlet air temperature of the regenerating fan III.

[0022] 5) The exhaust gas at a temperature of approximately 100°C in the fifth section of the upper cover is sent into the return air box in the fourth section by the regenerating fan IV as cooling air. When the exhaust gas temperature in the fifth section of the upper cover is higher than 100°C, the ratio of exhaust gas from the fifth section of the upper cover to ambient air is controlled by adjusting the opening of the regulating valve H upstream of the three-way pipe II, thereby controlling the outlet air temperature of the regenerating fan IV.

[0023] Preferably, the exhaust gas with a temperature of 200℃~250℃ in the three sections of the upper cover is sent into the return air box of the first section by the regenerating fan III as cooling air; when the exhaust gas temperature in the three sections of the upper cover is higher than 200℃, the ratio of exhaust gas from the three sections of the upper cover to ambient air is controlled by adjusting the opening of the regulating valve G upstream of the three-way pipe I, so as to control the outlet air temperature of the regenerating fan III.

[0024] The exhaust gas, with a temperature of 150℃~180℃ in the four sections of the upper cover, is purified by the dust removal system before being discharged.

[0025] Advantages of this invention:

[0026] 1) The sintered ore cooling exhaust gas waste heat cascade utilization system of the present invention uses the low temperature exhaust gas in the middle or middle-to-late stage as cooling air in the front stage of the ring cooler. The wind box that utilizes the return air of the waste heat boiler is moved to the rear in sections, which can increase the exhaust gas temperature in the front stage of the ring cooler and expand the heat collection area of ​​the waste heat boiler to more than 50% of the total area of ​​the ring cooler. This creates favorable conditions for recovering more waste heat from the exhaust gas through the waste heat boiler and improving the utilization rate of the waste heat boiler.

[0027] 2) The sintering ore cooling exhaust gas waste heat cascade utilization system of the present invention breaks the original correspondence between the ring cooler wind box and the upper cover section. By adjusting the direction of cooling exhaust gas through the valve on the upper cover air intake pipe, the heat extraction range of the waste heat boiler is not limited by the wind box section. It can adjust the proportion of exhaust gas of different temperatures entering the waste heat boiler as needed, thereby adjusting the inlet air temperature of the waste heat boiler. This ensures that the inlet air temperature of the waste heat boiler is not affected by the fluctuation of sintering production, creating favorable conditions for the efficient and stable operation of the boiler.

[0028] 3) The waste heat utilization system of sintered ore cooling exhaust gas of the present invention can recover and utilize a portion of the low-temperature exhaust gas in the middle or middle and rear sections that needs to be discharged in the prior art as the cooling air of the front section. This can increase the proportion of exhaust gas that is self-circulated on the ring cooler, significantly reduce the amount of exhaust gas discharged by the ring cooler, reduce the difficulty of disposing of this part of the exhaust gas, and create favorable conditions for achieving zero emissions of exhaust gas from the ring cooler. Attached Figure Description

[0029] Figure 1 This is a schematic diagram of the waste heat utilization system for sintered ore cooling exhaust gas of the present invention.

[0030] Figure 2 This is a schematic diagram of another embodiment of the present invention. Detailed Implementation

[0031] The specific embodiments of the present invention will be further described below with reference to the accompanying drawings.

[0032] The first implementation method is as follows: Figure 1 As shown, the present invention discloses a cascade utilization system for waste heat from sintered ore cooling exhaust gas, comprising an annular cooler 1, a sealed upper cover disposed on the upper part of the annular cooler, a wind box disposed on the lower part of the annular cooler, and a waste gas circulation system. The sealed upper cover, along the material advance direction, consists of, in sequence, upper cover section 111, upper cover section 112, upper cover section 113, upper cover section 114, and upper cover section 115. The wind box consists of, in sequence, return air section 121, return air section 122, return air section 123, return air section 124, and ambient temperature cooling wind box 125. The waste gas circulation system includes a waste heat boiler 2, a regenerative fan, a three-way pipe, and a regulating valve. Its characteristic is that:

[0033] The upper cover section 111 is connected to the waste heat boiler 2 via exhaust gas pipe A and regulating valve A21. The upper cover section 2 is connected to the waste heat boiler 2 via exhaust gas pipe B and regulating valve B22. The waste heat boiler 2 is connected to the inlet of the regenerative fan I3. The outlet of the regenerative fan I3 is connected to the return air section 122 and the return air section 123 via regulating valve C31 and regulating valve D32, respectively.

[0034] The upper cover section 113 is connected to the inlet of the regenerating air fan II4 via exhaust gas pipe C. The regenerating air fan II4 sends hot air to the sintering machine material surface for hot air sintering. The upper cover section 114 is connected to the inlet of the regenerating air fan III5 via exhaust gas pipe D, regulating valve E52, and three-way pipe I51. The outlet of the regenerating air fan III5 is connected to the return air box 121. The upper cover section 115 is connected to the inlet of the regenerating air fan IV6 via exhaust gas pipe E, regulating valve F62, and three-way pipe II61. The outlet of the regenerating air fan IV6 is connected to the return air box 121.

[0035] The return air box 124 is connected to the pipe, and the ambient temperature cooling box 125 is connected to the outlet of the ambient temperature cooling fan 7.

[0036] This invention provides an emergency vent valve A131 on the exhaust gas duct A of the first section of the upper cover, an emergency vent valve B132 on the exhaust gas duct B of the second section of the upper cover, an emergency vent valve C133 on the exhaust gas duct D of the fourth section of the upper cover, and an emergency vent valve D134 on the exhaust gas duct E of the fifth section of the upper cover. The operation of each emergency vent valve is as follows: Under normal production conditions, all emergency vent valves are closed, and exhaust gas is not directly discharged. When the operating regenerator fan suddenly malfunctions, the emergency vent valve corresponding to that section of the upper cover is opened, temporarily releasing the exhaust gas within that section of the upper cover. The machine is then shut down for maintenance after the sintered ore on the annular cooler has been cooled.

[0037] The three-way pipes I 51 and II 61 described in this invention are connected to the atmosphere via regulating valves G53 and H63, respectively. Their function is to control the ratio of exhaust gas from the upper hood (section 4 114 and section 5 115) to ambient air by adjusting the opening of the regulating valves upstream of the three-way pipes, thereby controlling the outlet air temperature of the regenerator fan.

[0038] The above-mentioned cascade utilization system for waste heat from sintered ore cooling gas is as follows:

[0039] 1) Under normal production conditions, all emergency vent valves are closed. The exhaust gas temperature discharged from the first section 111 of the upper cover of the annular cooler is about 400°C, and the exhaust gas temperature discharged from the second section 112 of the upper cover of the annular cooler is about 300°C. The two exhaust gases enter the waste heat boiler 2 through exhaust gas pipe A and exhaust gas pipe B respectively. After heat exchange and mixing in the waste heat boiler 2, the two exhaust gases are used as cooling air and sent to the return air second section air box 122 and return air third section air box 123 by the regenerative fan I3.

[0040] 2) When the inlet air temperature of waste heat boiler 2 is too high, open the regulating valve A21 or regulating valve B22. If the inlet air temperature of waste heat boiler 2 is still too high when regulating valve A21 or regulating valve B22 is fully open, open the corresponding emergency venting valve A131 or emergency venting valve B132 to draw in a certain amount of ambient air to regulate the inlet air temperature of waste heat boiler 2.

[0041] 3) The exhaust gas at a temperature of 200℃~250℃ in the three sections of the upper cover 113 is sent to the sintering machine material surface for hot air sintering through the regenerating blower II4;

[0042] 4) The exhaust gas with a temperature of approximately 150℃ to 180℃ in the fourth section 114 of the upper cover is sent into the first return air box 121 by the regenerating blower Ⅲ5 as cooling air; when the exhaust gas temperature in the fourth section 114 of the upper cover is higher than 150℃, the ratio of exhaust gas from the fourth section 114 of the upper cover to ambient air is controlled by adjusting the opening of the regulating valve G53 upstream of the three-way pipe Ⅰ51, so as to control the outlet air temperature of the regenerating blower Ⅲ5.

[0043] 5) The exhaust gas at a temperature of approximately 100°C in the upper five-section 115 is sent by the regenerating fan IV6 into the return air box 124 as cooling air. When the exhaust gas temperature in the upper five-section 115 is higher than 100°C, the ratio of exhaust gas from the upper five-section 115 to ambient air is controlled by adjusting the opening of the regulating valve H63 upstream of the three-way pipe II61, thereby controlling the outlet air temperature of the regenerating fan IV6.

[0044] The second implementation method is as follows: Figure 2 As shown, the upper cover three sections 113 of the present invention are connected to the inlet of the regenerating fan III5 through the exhaust gas pipe C, the regulating valve E52 and the three-way pipe I51, and the outlet of the regenerating fan III5 is connected to the return air first section air box 121. The upper cover four sections 114 are connected to the inlet of the dust removal system 8 through the exhaust gas pipe D.

[0045] In the second embodiment, the destination of the exhaust gas in the upper cover three-section 113 and upper cover four-section 114 is different from that in the first embodiment, while the other parts are the same as in the first embodiment.

[0046] The method of use is as follows: the exhaust gas with a temperature of 200℃~250℃ in the upper three-section 113 is sent into the return air box 121 by the regenerating fan Ⅲ5 as cooling air; when the exhaust gas temperature in the upper three-section 113 is higher than 200℃, the opening of the regulating valve G53 upstream of the three-way pipe Ⅰ51 is adjusted to control the ratio of exhaust gas from the upper three-section 113 to ambient air, thereby achieving the purpose of controlling the outlet air temperature of the regenerating fan Ⅲ5.

[0047] The exhaust gas at a temperature of 150℃~180℃ from the four sections 114 of the upper cover is purified by the dust removal system 8 before being discharged.

[0048] The above content only describes the technical route of the present invention. For sintering production lines of different scales, the number of fans can be increased and the operating temperature range can be adjusted according to actual production needs, which should also be included within the scope of protection of the present invention.

Claims

1. A cascade utilization system for waste heat from sintered ore cooling exhaust gas, comprising an annular cooler (1), a sealed upper cover installed on the upper part of the annular cooler, a wind box installed on the lower part of the annular cooler, and a waste gas circulation system, wherein the sealed upper cover is, in sequence along the material advance direction, an upper cover section 1 (111), an upper cover section 2 (112), an upper cover section 3 (113), an upper cover section 4 (114), and an upper cover section 5 (115), and the wind box is, in sequence, a return air section 1 wind box (121), a return air section 2 wind box (122), a return air section 3 wind box (123), a return air section 4 wind box (124), and a normal temperature cooling wind box (125), and the waste gas circulation system comprises a waste heat boiler (2), a regenerative fan, a three-way pipe, and a regulating valve, characterized in that: The upper cover section (111) is connected to the waste heat boiler (2) via exhaust gas pipe A and regulating valve A (21). The upper cover section (2) is connected to the waste heat boiler (2) via exhaust gas pipe B and regulating valve B (22). The waste heat boiler (2) is connected to the inlet of the regenerative fan I (3). The outlet of the regenerative fan I (3) is connected to the return air section 2 air box (122) and the return air section 3 air box (123) via regulating valve C (31) and regulating valve D (32) respectively. An emergency vent valve A (131) is provided on the exhaust gas pipe A of the first section of the upper cover, an emergency vent valve B (132) is provided on the exhaust gas pipe B of the second section of the upper cover, an emergency vent valve C (133) is provided on the exhaust gas pipe D of the fourth section of the upper cover, and an emergency vent valve D (134) is provided on the exhaust gas pipe E of the fifth section of the upper cover; The upper cover section 3 (113) is connected to the inlet of the regenerating fan II (4) through the exhaust gas pipe C. The regenerating fan II (4) sends hot air to the sintering machine material surface through the pipeline for hot air sintering. The upper cover section 4 (114) is connected to the inlet of the regenerating fan III (5) through the exhaust gas pipe D, the regulating valve E (52) and the three-way pipe I (51). Alternatively, the upper cover section 3 (113) is connected to the inlet of the regenerating fan III (5) through the exhaust gas pipe C, the regulating valve E (52) and the three-way pipe I (51). The outlet of the regenerating fan III (5) is connected to the return air section 1 air box (121). The upper cover section 4 (114) is connected to the inlet of the dust removal system (8) through the exhaust gas pipe D. The outlet of the regenerating fan III (5) is connected to the return air section 1 air box (121). The upper cover section 5 (115) is connected to the inlet of the regenerating fan IV (6) through the exhaust gas pipe E, regulating valve F (62) and three-way pipe II (61). The three-way pipe I (51) and three-way pipe II (61) are connected to the atmosphere through regulating valve G (53) and regulating valve H (63) respectively. The outlet of the regenerating fan IV (6) is connected to the return air section 4 air box (124) through the pipe. The ambient temperature cooling air box (125) is connected to the outlet of the ambient temperature cooling fan (7).

2. A method for using a cascade utilization system for waste heat from sintered ore cooling gas: The system employs the cascade utilization system for waste heat from sintered ore cooling gas as described in claim 1, characterized in that... 1) Under normal production conditions, all emergency vent valves are closed. The exhaust gas temperature discharged from the first section (111) of the upper cover of the ring cooler is 400℃, and the exhaust gas temperature discharged from the second section (112) of the upper cover of the ring cooler is 300℃. The two exhaust gases enter the waste heat boiler (2) through exhaust gas pipe A and exhaust gas pipe B respectively. After the two exhaust gases are heat exchanged and mixed by the waste heat boiler (2), they are used as cooling air and sent to the return air second section air box (122) and return air third section air box (123) by the return air fan I (3). 2) When the inlet air temperature of the waste heat boiler (2) is too high, open the regulating valve A (21) or regulating valve B (22). If the inlet air temperature of the waste heat boiler (2) is still too high when the regulating valve A (21) or regulating valve B (22) is fully open, open the corresponding emergency venting valve A (131) or emergency venting valve B (132) to draw in a certain amount of ambient air to regulate the inlet air temperature of the waste heat boiler (2). 3) The exhaust gas from the upper three sections (113) with a temperature of 200℃~250℃ is sent to the sintering machine material surface for hot air sintering through the regenerating blower II (4); The exhaust gas from the upper fourth section (114) with a temperature of 150℃~180℃ is sent into the return air box (121) by the regenerating blower III (5) as cooling air; when the exhaust gas temperature of the upper fourth section (114) is higher than 150℃, the ratio of exhaust gas from the upper fourth section (114) to ambient air is controlled by adjusting the opening of the regulating valve G (53) upstream of the three-way pipe I (51), thereby controlling the outlet air temperature of the regenerating blower III (5). Alternatively, the exhaust gas with a temperature of 200℃~250℃ from the upper three sections (113) is sent into the return air box (121) by the regenerating fan III (5) as cooling air; when the exhaust gas temperature of the upper three sections (113) is higher than 200℃, the ratio of exhaust gas from the upper three sections (113) to ambient air is controlled by adjusting the opening of the regulating valve G (53) upstream of the three-way pipe I (51), thereby achieving the purpose of controlling the outlet air temperature of the regenerating fan III (5); The exhaust gas from the four sections (114) of the upper cover, with a temperature of 150℃~180℃, is discharged after being purified by the dust removal system (8); 4) The exhaust gas with a temperature of about 100°C in the upper five section (115) is sent into the return air box (124) by the regenerating fan IV (6) as cooling air. When the exhaust gas temperature in the upper five section (115) is higher than 100°C, the ratio of exhaust gas from the upper five section (115) to ambient air is controlled by adjusting the opening of the regulating valve H (63) upstream of the three-way pipe II (61), so as to control the outlet air temperature of the regenerating fan IV (6).

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