Belt roaster process air circulation system suitable for vanadium-titanium magnetite pellet roasting

Abstract

This invention discloses a process air circulation system for a belt roaster applicable to the roasting of vanadium-titanium magnetite pellets. The regenerating fan's inlet is connected to the air box of the roasting section, and its outlet is connected to the exhaust hood. A cooling blower is connected to all air boxes in cooling section I and cooling section II via multiple branch pipes. The cooling blower is connected to the first air box in cooling section I in the direction of the trolley's movement via a first branch pipe. One end of the circulating cooling pipe where the circulating cooling fan is located is connected to the regenerating air flue at a first point, and the other end is connected to the first branch pipe at a second point. The first point is located on the outlet side of the regenerating fan. A tenth high-temperature butterfly valve is installed between the circulating cooling pipe and the circulating cooling fan at the first point, and an eleventh high-temperature butterfly valve is installed between the circulating cooling pipe and the circulating cooling fan at the second point. A third cooling air valve is connected to the circulating cooling pipe between the first point and the circulating cooling fan. A twelfth high-temperature butterfly valve is installed between the first branch pipe and the cooling blower at the second point.

Description

Technical Field

[0001] This invention relates to the field of belt roaster pellet roasting technology, and more particularly to a belt roaster process air circulation system applicable to vanadium-titanium magnetite pellet roasting. Background Technology

[0002] Vanadium-titanium magnetite pellets require a long preheating time, are not sensitive to roasting temperature, and have a narrow controllable temperature range, earning them the industry nickname of "dull ore." Currently, the only vanadium-titanium magnetite pelletizing processes are sintering and rotary kiln processes using chain grate machines, but both of these processes have numerous drawbacks.

[0003] Through experimental research and engineering practice, a reasonable process air circulation system has been developed for the belt roasting process of vanadium-titanium magnetite pelletizing. Currently, the reference oxygen content of flue gas from domestically operational belt roasting pelletizing production lines is all >18.5%, which does not meet the emission limit of ≤18% required by the "Ultra-Low Emission Standard for Air Pollutants in the Iron and Steel Industry" (DB13 / 2169-2018). This is a major headache for pelletizing plants. Summary of the Invention

[0004] Based on the above problems, this application provides a belt roaster process air circulation system applicable to the roasting of vanadium-titanium magnetite pellets.

[0005] This application provides a process air circulation system for a belt roaster applicable to the roasting of vanadium-titanium magnetite pellets. The belt roaster process air circulation system includes an adjacent first pair of set burners and a second pair of set burners. In the direction of the trolley's movement, the burners located before the first pair of set burners belong to the preheating section, and the burners located after the second pair of set burners belong to the roasting section. The first and second pairs of set burners are in the preheating section when the controlled temperature is between 850℃ and 1050℃, and in the roasting section when the controlled temperature is between 1150℃ and 1250℃. The belt roaster process air circulation system includes a regenerating fan, a cooling blower, and a circulating cooling fan. The inlet of the regenerating fan's flue is connected to the air box of the roasting section, and the outlet is connected to the exhaust hood. The cooling blower is connected to all the air boxes of Cooling Section I and Cooling Section II through multiple branch pipes. The cooling blower is connected to the first air box in Cooling Section I in the direction of the trolley's movement through the first branch pipe. One end of the circulating cooling pipe where the circulating cooling fan is located is connected to the regenerating air flue at the first point, and the other end is connected to the first branch pipe at the second point. The first point is located on the outlet side of the regenerating air fan. A tenth high-temperature butterfly valve is installed between the circulating cooling pipe and the circulating cooling fan at the first point, and an eleventh high-temperature butterfly valve is installed between the circulating cooling pipe and the circulating cooling fan at the second point. The third cooling air valve is connected to the circulating cooling pipe between the first point and the circulating cooling fan. A twelfth high-temperature butterfly valve is installed between the first branch pipe and the cooling blower at the second point.

[0006] In some implementations, the third cooling air valve is closed, the tenth high-temperature butterfly valve is opened, the twelfth high-temperature butterfly valve is closed, and the eleventh high-temperature butterfly valve is opened simultaneously to ensure that the reference oxygen content of the flue gas is ≤18%; at the same time, the tenth high-temperature butterfly valve is closed, the eleventh high-temperature butterfly valve is closed, and the twelfth high-temperature butterfly valve is opened, and the first branch pipe blows cold air into the first air box in the trolley running direction in the cooling section I through the cooling blower.

[0007] In some embodiments, a first air-cooled beam is provided at the junction of the drying section and the extraction section, a second air-cooled beam is provided at the junction of the extraction section and the preheating section, and a third air-cooled beam is provided at the junction of the calcination section and the homogenization section. The inlets of the first, second, and third air-cooled beams are all ambient cold air. The outlet of the first air-cooled beam is located in the first air box in the trolley running direction in the extraction section, the outlet of the second air-cooled beam is located in the first air box in the trolley running direction in the preheating section, and the outlet of the third air-cooled beam is located in the first air box in the trolley running direction in the homogenization section. The internal pressure of the first air box in the trolley running direction in the extraction section, the first air box in the trolley running direction in the preheating section, and the first air box in the trolley running direction in the homogenization section is set to be within the range of -1.5 kPa to -4.0 kPa.

[0008] In some embodiments, a dummy air box is installed under the partition wall between the drying section and the extraction section. The front and rear ends of the dummy air box are respectively sealed by a first partition and a second partition in the direction of trolley travel. A sealing air curtain is installed above the second partition seal. The inlet of the sealing air curtain is the drying section air box. The sealing air curtain blows into the extraction section fume hood to form a slight positive pressure at the dummy air box and the sealing air curtain, preventing the flue gas in the extraction section fume hood from flowing into the drying section fume hood.

[0009] In some embodiments, the process air circulation system of the belt roaster includes a drying blower and a drying exhaust blower. The inlet of the drying blower's flue is connected to the cooling section II hood, and the outlet is connected to the drying section air box. The drying exhaust blower's flue is connected to the drying section hood. A first cooling air valve is connected to the drying exhaust blower between the drying exhaust blower and the drying section hood. The drying blower's flue is connected to the drying exhaust blower through a second branch pipe. A fifth high-temperature butterfly valve is installed on the second branch pipe to regulate the temperature of the drying exhaust gas in the drying exhaust blower between 80°C and 120°C.

[0010] In some implementations, the outlet of the regenerated air flue is also connected to the preheating section at a forward position in the trolley's running direction, and the regenerated air flue is equipped with several high-temperature butterfly valves to control whether to input to the preheating section.

[0011] In some embodiments, the process air circulation system of the belt roaster includes a main induced draft fan. The inlet of the main induced draft fan flue is connected to the air box of the drying section and several air boxes of the preheating section. The main induced draft flue is equipped with several high-temperature butterfly valves to control whether hot air is introduced into the air box of the drying section.

[0012] In some embodiments, a third partition seal is provided below the trolley at the partition wall between the drying section and the preheating section, a fourth partition seal is provided below the trolley at the partition wall between the calcination section and the homogenization section, and a fifth partition seal is provided below the trolley at the partition wall between the cooling section I and the cooling section II. The third, fourth, and fifth partition seals are configured to move laterally and longitudinally to eliminate ash accumulation.

[0013] In some embodiments, the process air circulation system of the belt roaster includes a main induced draft fan and a drying blower. The inlet of the main induced draft fan flue is connected to the drying section air box and several air boxes in the preheating section. The inlet of the drying blower flue is connected to the cooling section hood and the outlet is connected to the main induced draft fan flue. The drying blower flue is equipped with an eighth high-temperature butterfly valve to control whether to input into the main induced draft fan flue. The reheat air flue is connected to the main induced draft fan flue through a third branch pipe. A ninth high-temperature butterfly valve is installed on the third branch pipe. The fifth cooling air valve is connected to the main induced draft fan flue at the inlet side of the main induced draft fan. In this way, the temperature of the main induced draft flue gas in the main induced draft fan flue is controlled at 140℃-180℃.

[0014] In some implementations, a second cold air valve is provided on the inlet side of the regenerating air fan.

[0015] The beneficial effects of this application are as follows: By controlling the temperature of the first pair of set burners at 850℃-1050℃ and the temperature of the second pair of set burners at 850℃-1050℃, the area can be used as a preheating section, extending the preheating time of the vanadium-titanium magnetite pellets to ensure that the titanium magnetite in the pellets is fully oxidized into titanium hematite; by controlling the temperature of the first pair of set burners at 1150-1250℃ and the temperature of the second pair of set burners at 1150-1250℃, the area can be used as a roasting section, extending the roasting time of the vanadium-titanium magnetite pellets and allowing for more precise adjustment of the pellet roasting temperature band curve; the process air circulation system can be adjusted and controlled according to actual production conditions during the roasting of vanadium-titanium magnetite pellets; When the third high-temperature air valve is closed, the tenth high-temperature butterfly valve is opened, the twelfth high-temperature butterfly valve is closed, and the eleventh high-temperature butterfly valve is opened, the hot air from the outlet of the regenerating fan (temperature approximately 340℃, oxygen content approximately 13%) is blown into the cooling section I by the circulating cooling fan, replacing part of the cold air (temperature approximately 25℃, oxygen content approximately 21%) drawn in by the cooling blower. This not only cools the upper pellets (temperature approximately 1100℃) but also reduces the reference oxygen content of the flue gas, ensuring that the reference oxygen content of the flue gas is ≤18%. Alternatively, the tenth high-temperature butterfly valve 510 and the eleventh high-temperature butterfly valve 511 can be closed, the twelfth high-temperature butterfly valve 512 can be opened, and the circulating cooling fan can be turned off. This channel is used as the cooling blower channel for cold air. Attached Figure Description

[0016] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention.

[0017] Figure 1 A schematic diagram of the process air circulation system of a belt roaster for vanadium-titanium magnetite pellet roasting provided in this application.

[0018] Attached reference numerals: 11-First cold air valve, 12-Second cold air valve, 13-Third cold air valve, 14-Fourth cold air valve, 15-Fifth cold air valve, 21-First air-cooled beam, 22-Second air-cooled beam, 23-Third air-cooled beam, 31-First partition seal, 32-Second partition seal, 33-Third partition seal, 34-Fourth partition seal, 35-Fifth partition seal, 4-Sealed air curtain, 51-First high-temperature butterfly valve, 52-Second high-temperature butterfly valve, 53-Third high-temperature butterfly valve, 54-Fourth high-temperature butterfly valve, 55-Fifth high-temperature butterfly valve, 56-Sixth high-temperature butterfly valve, 57-Seventh high-temperature butterfly valve, 58-Eighth high-temperature butterfly valve, 59-Ninth high-temperature butterfly valve, 510-Tenth high-temperature butterfly valve, 511-Eleventh high-temperature butterfly valve, 512-Twelfth high-temperature butterfly valve, 6-Dummy airbox, 71-First pair of set burners, 72-Second pair of set burners. Detailed Implementation

[0019] Please refer to Figure 1 A process air circulation system for a belt roaster suitable for roasting vanadium-titanium magnetite pellets is disclosed, which includes a main induced draft fan, a regenerating fan, a circulating cooling fan, a drying blower, a drying exhaust fan, and a cooling blower. Figure 1 The display shows the direction of the trolley's movement, and along the direction of the trolley's movement, there are sequentially arranged the drying section, the extraction section, the preheating section, the roasting section, the homogenization section, the cooling section I, and the cooling section II.

[0020] by Figure 1 The scheme is illustrated with examples, showing wind boxes #1, #2, #3 up to #18. #1 and #2 correspond to the drying section, #3 and #4 correspond to the extraction section, #5, #6 and #7 belong to the preheating section, #9, #10 and #11 correspond to the calcination section, #12 corresponds to the homogenization section, #13, #14, #15 and #16 correspond to the cooling section I, and #17 and #18 correspond to the cooling section II.

[0021] Figure 1 Specifically, it involves the first cold air valve 11, the second cold air valve 12, the third cold air valve 13, the fourth cold air valve 14, the fifth cold air valve 15, the first air-cooled beam 21, the second air-cooled beam 22, the third air-cooled beam 23, the first partition seal 31, the second partition seal 32, the third partition seal 33, the fourth partition seal 34, the fifth partition seal 35, the sealing air curtain 4, the first high-temperature butterfly valve 51, the second high-temperature butterfly valve 52, the third high-temperature butterfly valve 53, the fourth high-temperature butterfly valve 54, the fifth high-temperature butterfly valve 55, the sixth high-temperature butterfly valve 56, the seventh high-temperature butterfly valve 57, the eighth high-temperature butterfly valve 58, the ninth high-temperature butterfly valve 59, the tenth high-temperature butterfly valve 510, the eleventh high-temperature butterfly valve 511, the twelfth high-temperature butterfly valve 512, the dummy air box 6, the first pair of set burners 71, and the second pair of set burners 72.

[0022] The process air circulation system of the belt roaster includes an adjacent first pair of set burners 71 and a second pair of set burners 72. In the direction of trolley travel, the burners located in front of the first pair of set burners 71 belong to the preheating section, and the burners located after the second pair of set burners 72 belong to the roasting section. When the temperature of the first pair of set burners 71 and the second pair of set burners 72 is controlled at 850℃-1050℃, it belongs to the preheating section, and when the temperature is controlled at 1150-1250℃, it belongs to the roasting section.

[0023] By controlling the first pair of set burners 71 ( Figure 1 The temperature of the 7 / 8 burner is between 850℃ and 1050℃, controlling the second pair of set burners 72 ( Figure 1The temperature of the 9 / 10 burners is between 850℃ and 1050℃, and the area in this zone can be used as a preheating section to extend the preheating time of the vanadium-titanium magnetite pellets, so as to ensure that the titanium magnetite in the pellets is fully oxidized into titanium hematite; by controlling the temperature of the first pair of set burners 71 at 1150-1250℃ and the temperature of the second pair of set burners 72 at 1150-1250℃, the area in this zone can be used as a roasting section to extend the roasting time of the vanadium-titanium magnetite pellets, and to more finely adjust the pellet roasting temperature band curve.

[0024] The process air circulation system of the belt roaster includes a regenerating fan, a cooling blower, and a circulating cooling fan. The inlet of the regenerating air duct installed on the regenerating fan is connected to the air box of the roasting section, and the outlet is connected to the exhaust hood. The cooling blower is connected to all the air boxes of the cooling section I and cooling section II through multiple branch pipes. The cooling blower is connected to the first air box in the trolley running direction in the cooling section I through the first branch pipe. One end of the circulating cooling pipe where the circulating cooling fan is located is connected to the regenerating air duct at the first point, and the other end is connected to the first branch pipe at the second point. The first point is located on the outlet side of the regenerating fan. A tenth high-temperature butterfly valve 510 is installed between the circulating cooling pipe and the circulating cooling fan at the first point, and an eleventh high-temperature butterfly valve 511 is installed between the circulating cooling pipe and the circulating cooling fan at the second point. A third cooling air valve 13 is connected to the circulating cooling pipe between the first point and the circulating cooling fan. A twelfth high-temperature butterfly valve 512 is installed between the first branch pipe and the cooling blower at the second point.

[0025] The system roasts vanadium-titanium magnetite pellets. The process air circulation system can be adjusted and controlled according to the actual production situation. When producing certain raw materials, the reference oxygen content of the flue gas in the process production line is >18.5%, and it needs to be adjusted according to the first type of scheme below; when producing certain raw materials, the reference oxygen content of the flue gas in the process production line is 18%, and normal production is carried out according to the second type of scheme below.

[0026] For the first type of solution, please refer to... Figure 1 Simultaneously, the third cooling air valve 13 is closed, the tenth high-temperature butterfly valve 510 is opened, the twelfth high-temperature butterfly valve 512 is closed, and the eleventh high-temperature butterfly valve 511 is opened. The hot air from the outlet of the regenerating fan (temperature approximately 340℃, oxygen content approximately 13%) is blown into the cooling section I by the circulating cooling fan, replacing part of the cold air (temperature approximately 25℃, oxygen content approximately 21%) drawn in by the cooling blower. This not only cools the upper pellets (temperature approximately 1100℃) but also reduces the reference oxygen content of the flue gas, ensuring that the reference oxygen content of the flue gas is ≤18%.

[0027] The second option involves closing the tenth high-temperature butterfly valve 510 and the eleventh high-temperature butterfly valve 511, opening the twelfth high-temperature butterfly valve 512, and shutting down the circulating cooling fan. This channel serves as the cooling blower channel, using cold air. The cooling blower includes blowing cold air into the No. 13 air box via the first branch pipe. The No. 13 air box is the first air box in the trolley running direction in the cooling section I.

[0028] In summary, the belt roaster process air circulation system proposed in this application not only solves the practical improvement problem of vanadium-titanium magnetite pellets in the preheating or roasting stage, but also ensures that the reference oxygen content of flue gas is below 18%, meeting the new ultra-low emission standards for air pollutants in the iron and steel industry.

[0029] In some implementation methods, please refer to Figure 1 A first air-cooled beam 21 is installed at the junction of the drying and extraction sections; a second air-cooled beam 22 is installed at the junction of the extraction and preheating sections; and a third air-cooled beam 23 is installed at the junction of the calcination and homogenization sections. The inlets of all three beams are ambient cold air. The outlet of the first air-cooled beam 21 is located in wind box #3, which is the first wind box in the extraction section along the trolley's direction of travel. The outlet of the second air-cooled beam 22 is located in wind box #5, which is the first wind box in the preheating section along the trolley's direction of travel. The outlet of the third air-cooled beam 23 is located in wind box #12, which is the first wind box in the homogenization section along the trolley's direction of travel. The internal pressure of wind boxes #3, #5, and #12 is limited to the range of -1.5 kPa to -4.0 kPa. Ambient cold air is drawn in by the negative pressure of the wind boxes to cool the partition wall.

[0030] In some implementation methods, please refer to Figure 1 A false bellows 6 is installed under the partition wall between the drying section and the extraction section. The false bellows 6 is actually set in the original No. 3 bellows area. The false bellows 6 area is formed by using the first partition seal 31 and the second partition seal 32 at the front and rear ends in the trolley running direction, respectively.

[0031] In actual operation, the fume hoods of the blast drying section, the fume hoods of the extraction drying section, and the air box of the extraction drying section are under negative pressure, while the air box of the blast drying section is under positive pressure. Please refer to... Figure 1 A sealing air curtain 4 is installed above the second partition seal 32, with the inlet of the sealing air curtain 4 being the blower section air box. The sealing air curtain 4 blows into the exhaust section fume hood, creating a slight positive pressure at the location of the dummy air box 6 and the sealing air curtain 4. This prevents the flue gas in the exhaust section fume hood from flowing into the blower section fume hood, thus ensuring that the SO2 content in the blower section fume hood is ≤20mg / Nm³. 3 .

[0032] In some implementation methods, please refer to Figure 1The process air circulation system of the belt roaster includes a drying blower and a drying exhaust fan. The inlet of the drying blower's flue is connected to the cooling section II hood. Some outlets of the drying blower's flue are connected to the drying section air box. The drying exhaust fan's flue is connected to the drying section hood. The first cooling air valve 11 is connected to the drying exhaust fan between the drying exhaust fan and the drying section hood. The drying blower's flue is connected to the drying exhaust fan through a second branch pipe. A fifth high-temperature butterfly valve 55 is installed on the second branch pipe.

[0033] When the temperature of the exhaust gas from the blower is below 80℃, open the fifth high-temperature butterfly valve 55 and close the first cooling air valve 11, so that the exhaust gas (temperature 200℃-350℃) from the blower flue enters the blower exhaust duct, increasing the temperature of the exhaust gas to ≥80℃, so as to meet the requirements of the equipment used in the subsequent processes.

[0034] When the temperature of the blower exhaust gas is higher than 120℃, close the fifth high-temperature butterfly valve 55 and open the first cold air valve 11 to introduce cold air to reduce the temperature of the blower exhaust gas, so that the temperature of the blower exhaust gas is ≤120℃.

[0035] In some implementation methods, please refer to Figure 1 The outlet of the regenerated air flue is also connected to the preheating section at the forward position in the direction of the trolley's movement. Figure 1 Specifically, areas A / B, C / D, E / F, and the 1 / 2 burner area are designated as burner zones; areas A / B, C / D, and E / F do not have burner installations. The regenerative air flue is equipped with several high-temperature butterfly valves to control whether air is supplied to the preheating section. Figure 1 The valves are respectively the first high-temperature butterfly valve 51, the second high-temperature butterfly valve 52, the third high-temperature butterfly valve 53, and the fourth high-temperature butterfly valve 54.

[0036] By adjusting the first to fourth high-temperature butterfly valves 54, the airflow of regenerated flue gas (temperature approximately 340℃) into the A / B, C / D, E / F, and 1 / 2 burner zones (temperature 500-900℃) is controlled to adjust the temperature gradient in these zones, thereby better approximating the preheating temperature curve of vanadium-titanium magnetite pellets and achieving a better preheating effect.

[0037] In some embodiments, the process air circulation system of the belt roaster includes a main induced draft fan. The inlet of the main induced draft fan flue is connected to the air box of the drying section and several air boxes of the preheating section. The main induced draft flue is equipped with several high-temperature butterfly valves to control whether hot air is introduced into the air box of the drying section. Figure 1 The image shows the sixth high-temperature butterfly valve 56 and the seventh high-temperature butterfly valve 57. By adjusting the opening of the sixth high-temperature butterfly valve 56 and the seventh high-temperature butterfly valve 57, the flow rate and pressure of the drying air box are controlled to prevent the green balls from becoming too wet and suddenly falling and sticking after drying.

[0038] In some embodiments, a third partition seal 33 is provided below the trolley at the partition wall between the drying section and the preheating section, a fourth partition seal 34 is provided below the trolley at the partition wall between the calcination section and the homogenization section, and a fifth partition seal 35 is provided below the trolley at the partition wall between the cooling section I and the cooling section II. The third partition seal 33, the fourth partition seal 34 and the fifth partition seal 35 can move laterally and longitudinally, effectively eliminating the ash accumulation phenomenon.

[0039] In some implementation methods, please refer to Figure 1 The process air circulation system of the belt roaster includes a main induced draft fan and a drying blower. The inlet of the main induced draft fan flue is connected to the air box of the drying section and several air boxes of the preheating section. The inlet of the drying blower flue is connected to the cooling section II hood, and the outlet is connected to the main induced draft fan flue. The drying blower flue is equipped with an eighth high-temperature butterfly valve 58 to control whether to input into the main induced draft fan flue. The reheat air flue is connected to the main induced draft fan flue through a third branch pipe. A ninth high-temperature butterfly valve 59 is installed on the third branch pipe. The fifth cooling air valve 15 is connected to the main induced draft fan flue at the inlet side.

[0040] When the temperature of the main induced draft flue gas is <140℃, the opening of the eighth high-temperature butterfly valve 58 can be adjusted to introduce dry flue gas (temperature 200-350℃) into the main induced draft flue, or the opening of the ninth high-temperature butterfly valve 59 can be adjusted to introduce reheated flue gas (temperature about 340℃) into the main induced draft flue, so as to increase the temperature of the main induced draft flue gas to ≥140℃.

[0041] When the main exhaust gas temperature is >180℃, open the fifth cold air valve 15 to introduce cold air and lower the main exhaust temperature so that the main exhaust temperature is ≤180℃.

[0042] In some embodiments, a second cold air valve 12 is provided on the inlet side of the regenerating fan. The second cold air valve 12 is connected to the regenerating air flue through a branch pipe. When the temperature of the regenerating fan is too high during operation, the opening of the second cold air valve 12 can be adjusted to draw in cold air to reduce the equipment temperature and ensure equipment safety.

[0043] Similarly, a third cold air valve 13 is installed on the inlet side of the circulating cooling fan, and the third cold air valve 13 is connected to the circulating cooling flue through a branch pipe; a fourth cold air valve 14 is installed on the inlet side of the blower, and the fourth cold air valve 14 is connected to the blower flue through a branch pipe.

[0044] Although preferred embodiments of the invention have been described, those skilled in the art, upon learning the basic inventive concept, can make other changes and modifications to these embodiments. Therefore, the appended claims are intended to be interpreted as including both the preferred embodiments and all changes and modifications falling within the scope of the invention.

[0045] Obviously, those skilled in the art can make various modifications and variations to this invention without departing from its spirit and scope. Therefore, if these modifications and variations fall within the scope of the claims of this invention and their equivalents, this invention also intends to include these modifications and variations.

Claims

1. A process air circulation system for a belt roaster suitable for roasting vanadium titano-magnetite pellets, characterized in that, The belt roaster process air circulation system includes: The first pair of set burners and the second pair of set burners, in the direction of the trolley's movement, the burner in front of the first pair of set burners belongs to the preheating section, and the burner in the rear of the second pair of set burners belongs to the calcination section. When the temperature of the first pair of set burners and the second pair of set burners is controlled at 850℃-1050℃, they belong to the preheating section, and when the temperature is controlled at 1150-1250℃, they belong to the calcination section. The system includes a regenerating air fan, a cooling blower, and a circulating cooling fan. The inlet of the regenerating air duct where the regenerating air fan is installed is connected to the air box of the roasting section, and the outlet is connected to the exhaust hood. The cooling blower is connected to all the air boxes of the cooling section I and cooling section II respectively through multiple branch pipes. The cooling blower is connected to the first air box in the trolley running direction of the cooling section through the first branch pipe. One end of the circulating cooling pipe where the circulating cooling fan is located is connected to the regenerating air duct at a first point, and the other end is connected to the first branch pipe at a second point. The first point is located on the outlet side of the regenerating air fan. A tenth high-temperature butterfly valve is installed between the circulating cooling pipe and the circulating cooling fan at the first point, and an eleventh high-temperature butterfly valve is installed between the circulating cooling pipe and the circulating cooling fan at the second point. A third cooling air valve is connected to the circulating cooling pipe between the first point and the circulating cooling fan. A twelfth high-temperature butterfly valve is installed between the first branch pipe and the cooling blower at the second point.

2. The traveling grate process air circulation system as claimed in claim 1, characterized in that, Simultaneously close the third cold air valve, open the tenth high-temperature butterfly valve, close the twelfth high-temperature butterfly valve, and open the eleventh high-temperature butterfly valve to ensure that the reference oxygen content of the flue gas is ≤18%; Simultaneously, the tenth high-temperature butterfly valve and the eleventh high-temperature butterfly valve are closed, and the twelfth high-temperature butterfly valve is opened. The first branch pipe blows cold air into the first air box in the cooling section I in the direction of the trolley's movement through the cooling blower.

3. The traveling grate process air circulation system of claim 1, wherein, A first air-cooled beam is installed at the junction of the drying section and the extraction section, a second air-cooled beam is installed at the junction of the extraction section and the preheating section, and a third air-cooled beam is installed at the junction of the calcination section and the homogenization section. The inlets of the first, second, and third air-cooled beams are all ambient cold air. The outlet of the first air-cooled beam is located in the first air box in the trolley running direction in the extraction section, the outlet of the second air-cooled beam is located in the first air box in the trolley running direction in the preheating section, and the outlet of the third air-cooled beam is located in the first air box in the trolley running direction in the homogenization section. The internal pressure of the first air box in the trolley running direction in the extraction section, the first air box in the trolley running direction in the preheating section, and the first air box in the trolley running direction in the homogenization section is set to be within the range of -1.5 kPa to -4.0 kPa.

4. The traveling grate kiln process air circulation system as claimed in claim 1, wherein, A dummy air box is installed under the partition wall between the drying section and the extraction section. The front and rear ends of the dummy air box are respectively sealed by a first partition and a second partition in the direction of trolley movement. A sealing air curtain is installed above the second partition seal. The inlet of the sealing air curtain is the drying section air box. The sealing air curtain blows into the extraction section fume hood to form a slight positive pressure at the dummy air box and the sealing air curtain, preventing the smoke in the extraction section fume hood from flowing into the drying section fume hood.

5. The traveling grate kiln process air circulation system as claimed in claim 1, wherein, The process air circulation system of the belt roaster includes a drying blower and a drying exhaust fan. The inlet of the drying blower's flue is connected to the cooling section II hood, and the outlet is connected to the drying section air box. The drying exhaust fan's flue is connected to the drying section hood. A first cooling air valve is connected to the drying exhaust fan between the drying exhaust fan and the drying section hood. The drying blower's flue is connected to the drying exhaust fan through a second branch pipe. A fifth high-temperature butterfly valve is installed on the second branch pipe to regulate the drying exhaust gas temperature of the drying exhaust fan to 80℃-120℃.

6. The traveling grate kiln process air circulation system as claimed in claim 1, wherein, The outlet of the regenerating air flue is also connected to the preheating section at the forward position in the trolley's running direction. The regenerating air flue is equipped with several high-temperature butterfly valves to control whether to input air into the preheating section.

7. The traveling grate kiln process air circulation system as claimed in claim 1, wherein, The process air circulation system of the belt roaster includes a main induced draft fan. The inlet of the main induced draft fan is connected to the air box of the drying section and several air boxes of the preheating section. The main induced draft fan flue is equipped with several high-temperature butterfly valves to control whether hot air is introduced into the air box of the drying section.

8. The traveling grate kiln process air circulation system as claimed in claim 1, wherein, A third partition seal is installed below the trolley at the partition wall between the drying section and the preheating section; a fourth partition seal is installed below the trolley at the partition wall between the calcination section and the homogenization section; and a fifth partition seal is installed below the trolley at the partition wall between the cooling section I and the cooling section II. The third, fourth, and fifth partition seals are designed to move laterally and longitudinally to eliminate ash accumulation.

9. The traveling grate kiln process air circulation system of claim 1, wherein, The belt roaster process air circulation system includes a main induced draft fan and a drying blower. The inlet of the main induced draft fan's flue is connected to the drying section air box and several air boxes in the preheating section. The inlet of the drying blower's flue is connected to the cooling section II hood, and the outlet is connected to the main induced draft fan flue. The drying blower flue is equipped with an eighth high-temperature butterfly valve to control whether to input air into the main induced draft fan flue. The regenerated air flue is connected to the main induced draft fan flue through a third branch pipe. A ninth high-temperature butterfly valve is installed on the third branch pipe. The fifth cooling air valve is connected to the main induced draft fan flue at the inlet side of the main induced draft fan. In this way, the temperature of the main induced draft flue gas in the main induced draft fan flue is controlled at 140℃-180℃.

10. The traveling grate kiln process air circulation system of claim 1, wherein, The inlet side of the regenerating air fan is equipped with a second cold air valve.

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