Pellet production process and preparation system based on tail gas circulation O2-H2-CO2 fuel

Abstract

The invention discloses a pellet production process and a pellet preparation system based on tail gas circulation O2-H2-CO2 fuel, and belongs to the field of steel industry production, physical heat of tail gas in the production process is used for drying and preheating pellets, H2-containing gas, industrial pure oxygen and CO2-containing gas are mixed to serve as fuel gas, and the fuel gas is used as fuel gas; wherein CO2 gas is used as shielding gas when system equipment works. Waste heat of tail gas generated by combustion of hydrogen-rich fuel gas and industrial pure oxygen is fully utilized, and the utilization efficiency of heat prepared by a pellet production process is greatly improved; near-zero input of pulverized coal and nitrogen prepared through the pellet production technology is achieved, generation of COX and NOX in the production process is reduced from the source, the advantages of being economical and environmentally friendly are achieved, and green, sustainable, low-carbon and high-quality development of the iron and steel industry is facilitated.

Description

Technical Field

[0001] The present invention relates to the field of green, sustainable and efficient production of pellets in iron and steel metallurgical processes, and in particular to a method for preparing pellets based on tail gas recycling. 2 -H 2 -CO 2 Fuel pellet production process and preparation system. Background Art

[0002] Pelletized ore has important application value in the blast furnace ironmaking process. Due to the late start of pelletizing technology in my country, there are still some problems in the chain grate machine-rotary kiln-ring cooler process pelletizing production process. There is a big gap with international advanced steel companies in terms of energy conservation and emission reduction. For example, coke oven gas, blast furnace gas or pulverized coal is used as fuel in the rotary kiln, and air is introduced as a flame retardant. The heat generated is used for the heat required for drying and preheating of unroasted pelletized ore. However, since the coke oven gas, blast furnace gas or pulverized coal used as fuel is burned in an air environment, a large amount of carbon dioxide (CO2) will be generated under high temperature conditions. 2 ), nitrogen oxides (NO x ), sulfur dioxide (SO 2 ) and other atmospheric pollutants, which have an impact on the natural environment; secondly, during the operation of the equipment, the fuel and kinetic energy consumption is high, and carbon dioxide (CO 2 ), nitrogen oxides (NO x ), sulfur dioxide (SO 2 ) and other atmospheric pollutants are emitted in large quantities and carry a large amount of physical heat, which in turn leads to a decrease in physical thermal efficiency. According to statistics, during the pelletizing process, carbon dioxide (CO 2 ) emissions account for about 11.5% of the total emissions from the steel industry; nitrogen oxides (NO x ) emissions account for about 5% of the total emissions from the steel industry; sulfur dioxide (SO 2 ) emissions account for about 1% of the total emissions from the steel industry.

[0003] Therefore, the chain grate-rotary kiln-ring cooler pelletizing process and equipment are improved to make full use of the waste heat carried by the tail gas and reduce the carbon dioxide (CO 2 ), nitrogen oxides (NO x ), sulfur dioxide (SO 2 ) and other atmospheric pollutant emissions, which is of great significance to achieving low-carbon, green and high-quality development as well as transformation and upgrading of the steel industry. Summary of the invention

[0004] The purpose of the present invention is to provide a method based on tail gas recycling O 2 -H 2 -CO 2The fuel pellet production process and preparation system achieves near-zero input of coal powder and nitrogen in the entire system, reducing CO2 emissions from the source during the production process. X with NO X The generation of CO after the tail gas is recycled 2 The gas continues to be used as fuel for roasting in the rotary kiln to achieve CO 2 The recycling and recovery of gases will reduce emissions and promote low-carbon, green and high-quality development as well as transformation and upgrading of the steel industry.

[0005] The present invention adopts the following technical solutions: A tail gas recycle O 2 -H 2 -CO 2 A fuel pellet production process, characterized in that the process comprises the following steps: Step 1: The high-temperature rotary kiln tail gas generated by the combustion of the rotary kiln mixed fuel is introduced into the preheating section of the chain grate to preheat the unroasted pellets in the chain grate.

[0006] Step 2: The low-temperature chain grate preheating section tail gas generated after the heat exchange in the preheating process of step 1 is pressurized by the booster fan I and introduced into the tail gas internal circulation section dust removal and dehydration device, and then introduced into the ring cooling section of the ring cooler to forcefully cool the roasted finished pellets.

[0007] Step 3: Install gas composition detection device I at the outlet pipeline of the cooling section of the cooling machine to analyze the H 2 concentration; the tail gas is then introduced into the hydrogen membrane separation device to separate the H 2 Gas separation.

[0008] Step 3a: Separate the H2 from the hydrogen membrane separation device 2 The gas is pressurized by the booster fan III and then introduced into the fuel proportioning system to mix with industrial pure oxygen, CO 2 The gases are mixed in proportion as fuel for roasting in the rotary kiln; Step 3b: The tail gas separated by the hydrogen membrane separation device is pressurized by the booster fan II and then introduced into the chain grate drying section to dry the unroasted pellets.

[0009] Step 4: The tail gas from the drying section of the chain grate is pressurized by the booster fan IV and then introduced into the dust removal, dehydration, desulfurization and denitrification device of the tail gas external circulation section, and a gas composition detection device II is set at the outlet of the equipment; Step 4a: If the exhaust gas from the grate drying section contains CO 2 If the gas concentration is lower than 75%, it will be directly discharged into the air through the reversing valve I; Step 4b: If the exhaust gas from the grate drying section contains CO 2 If the gas concentration is higher than 75%, it is introduced into the CO2 Crude purification device to obtain CO 2 Gas concentration greater than 98% CO 2 gas, and store it in CO 2 The gas is then pressurized by the booster fan V and introduced into the fuel proportioning system to mix with industrial pure oxygen and H 2 The gases are mixed in proportion and used as fuel for rotary kiln roasting.

[0010] Furthermore, the ignition and heating mode of the rotary kiln is: 2 Gas, industrial pure oxygen and CO 2 The gas is mixed in proportion in the fuel proportioning system and burned as rotary kiln fuel, of which CO 2 The gas is used as a protective gas when the system equipment is working. When the furnace temperature of the rotary kiln reaches 1250°C, the pellet production process preparation operation mode remains unchanged.

[0011] A tail gas recycle O 2 -H 2 -CO 2 The fuel pellet production and preparation system comprises: a grate drying section, a grate preheating section, a rotary kiln, a ring cooler ring cooling section I, a ring cooler ring cooling section II, and is characterized in that the fuel containing H 2 Gas, industrial pure oxygen and CO 2 The gases are connected to the fuel proportioning system through pipelines P1, P2, and P3 respectively. The hydrogen separated by the hydrogen membrane separation device 2The gas passes through pipeline P10, through booster fan III, and then through pipeline P11 to connect with the fuel proportioning system. The gas outlet of the fuel proportioning system is connected with the fuel nozzle through pipeline P4. The lower exhaust port of the chain grate preheating section is connected with booster fan I through pipeline P5. The booster fan I is connected with the dust removal and dehydration device of the exhaust gas internal circulation section through pipeline P6. The dust removal and dehydration device of the exhaust gas internal circulation section is connected with the lower air inlet of the ring cooling section I of the ring cooler through pipeline P7. The upper exhaust port of the ring cooling section I of the ring cooler is connected with the inlet of the hydrogen membrane separation device through pipeline P8. The gas composition detection device I is connected with pipeline P8 through pipeline P9. The first outlet of the hydrogen membrane separation device is connected with the inlet of booster fan III through pipeline P10. The outlet of booster fan III is connected with the inlet of booster fan III through pipeline P1. 1 is connected to the fuel proportioning system, the other outlet of the hydrogen membrane separation device is connected to the inlet of the booster fan II through the pipeline P12, the outlet of the booster fan II is connected to the upper air inlet of the chain grate drying section through the pipeline P13, the lower air outlet of the chain grate drying section is connected to the air inlet of the booster fan IV through the pipeline P14, the air outlet of the booster fan IV is connected to the air inlet of the dust removal, dehydration, desulfurization and denitration device of the tail gas external circulation section through the pipeline P15, the air outlet of the dust removal, dehydration, desulfurization and denitration device of the tail gas external circulation section is connected to the inlet of the reversing valve I through the pipeline P16, the gas composition detection device II is connected to the pipeline P17 and the pipeline P16, the first outlet of the reversing valve I is connected to the vent through P18 and discharged into the air, and the other outlet of the reversing valve I is connected to the CO 2 Crude purification unit inlet connection, CO 2 The outlet of the crude purification unit is connected to CO through pipeline P20. 2 Gas tank inlet connection, CO 2 The outlet of the gas storage tank is connected to the inlet of the booster fan V through the pipeline P21, and the outlet of the booster fan V is connected to the fuel proportioning system through the pipeline P22.

[0012] Furthermore, the system includes a feed inlet atmosphere protection device and a ring cooler body atmosphere protection device, wherein the feed inlet atmosphere protection device is installed at the head position of the chain grate machine, and the ring cooler body atmosphere protection device is installed between the ring cooling section I and the ring cooling section II of the ring cooler, and the exhaust gas of the ring cooling section I of the ring cooler is introduced into the ring cooler body atmosphere protection device.

[0013] Furthermore, the fuel used in the rotary kiln contains H 2 The gas includes at least one of natural gas, shale gas, biomass cracking gas, and hydrogen; the oxygen concentration in industrial pure oxygen is ≥ 99.5 vol%; and contains CO 2 Gas CO 2 Concentration ≥98vol% Furthermore, the ring cooling section II of the ring cooler uses normal temperature air as cooling gas for the roasted finished pellets.

[0014] Beneficial effects: Compared with the prior art, the beneficial technical effects brought by the technical solution of the present invention are: (1) The present invention uses a 2 Gas, industrial pure oxygen and containing CO 2 The gas mixture is used as the fuel for rotary kiln roasting, replacing the original process of using pulverized coal, coke oven gas, etc. as the fuel for rotary kiln roasting; and the CO introduced into the fuel 2 The gas replaces the nitrogen in the air used in the original process as the protective gas for the system equipment, reducing CO in the production process from the source X with NO X Generation of.

[0015] (2) High-temperature tail gas is used for drying and preheating of pellets; and the dry and preheated tail gas is used to realize forced cooling of pellets and absorb the heat of finished pellets, thus making the most of the preheating generated by fuel combustion in the pellet production system.

[0016] (3) Use of CO 2 The gas replaces the nitrogen in the air used in the original process as the protective gas when the system equipment is working, achieving near-zero nitrogen input in the system, improving the heat utilization rate of the entire system and ultimately generating a gas containing less CO 2 The tail gas of the gas can be treated by dust removal, dehydration, desulfurization and other tail gas treatment methods and CO 2 After purification, it is used as CO in the fuel proportioning system 2 Gas fuel input to achieve CO 2 The gas is recycled multiple times. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is a system schematic diagram of the pellet production process and preparation system of the present invention.

[0018] Figure 1 Middle: chain grate drying section (C1), chain grate preheating section (C2), rotary kiln (C3), ring cooler ring cooling section I (C4), ring cooler ring cooling section II (C5), booster fan I (1), exhaust gas internal circulation section dust removal and dehydration device (2), gas composition detection device I (3), hydrogen membrane separation device (4), booster fan II (5), booster fan III (6), fuel proportioning system (7), booster fan IV (8), exhaust gas external circulation section dust removal, dehydration, desulfurization and denitrification device (9), gas composition detection device II (10), reversing valve I (11), CO 2 Crude purification unit (12), CO 2 Gas storage cabinet (13), booster fan V (14), fuel nozzle (15).

[0019] The gases in the system are numbered as follows: tail gas from rotary kiln (C3) (a), tail gas from grate preheating section (C2) (b), tail gas from ring cooler ring cooling section (C4) (c), tail gas from grate drying section (C1) (d), CO 2 Gas (e). DETAILED DESCRIPTION

[0020] In order to facilitate the understanding of the present invention, the present invention will be described in more comprehensive and detailed manner in conjunction with preferred actual production examples, but the protection scope of the present invention is not limited to the following specific examples. Unless otherwise specified, the various reagents and raw materials used in the present invention are commodities purchased from the market or products that can be prepared by known methods.

[0021] In this embodiment, the system and method are applied to an actual production device of a steel enterprise with an annual output of 750,000 tons of pelletized ore chain grate-rotary kiln-ring cooler.

[0022] A tail gas recycle O 2 -H 2 -CO 2 The fuel pellet production process includes the following steps: Example 1

[0023] Step 1: At the 0th minute of system operation, the rotary kiln enters the ignition and heating mode: 2 Gas, industrial pure oxygen and CO 2 The gas is mixed in the fuel proportioning system, and the mixing ratio (volume ratio) is CO 2 : H 2 : O 2 =5:2:1, CO 2 Flow rate: 24000Nm 3 / h,H 2 Flow rate: 9600Nm 3 / h,O 2 Flow rate: 4800Nm 3 / h. Gas composition of rotary kiln tail gas after roasting: 76.54 vol% CO 2 ,22.63 vol%H 2 O,0.5187 vol% H 2 , flow rate is 33600 Nm 3 / h, the temperature is 620℃, and it is introduced into the preheating section of the chain grate machine to preheat the unroasted pellets in the preheating section of the chain grate machine.

[0024] Step 2: The temperature of the exhaust gas in the chain grate preheating section after heat exchange is 120°C, and it is introduced into the exhaust gas internal circulation section dust removal and dehydration device through the booster fan I. The treated exhaust gas composition is 94.28 vol% CO 2,0.4921 vol% H 2 , and then it is led to the ring cooling section I of the ring cooler for forced cooling of the roasted pellets and absorbing the heat of the finished pellets.

[0025] Step 3: After the heat exchange of the ring cooling section I of the ring cooler, the temperature of the ring cooling tail gas of the ring cooler is 400°C. The tail gas of the ring cooling section of the ring cooler is introduced into the gas composition detection device I to analyze the H 2 concentration; then introduce the hydrogen into the hydrogen membrane separation device to separate the H 2 Gas separation.

[0026] Step 3a: Separate the H 2 After being pressurized by the booster fan III, it is introduced into the fuel proportioning system with a concentration of 99%, mixed with industrial pure oxygen and CO 2 The gas mixture is used as fuel for roasting in the rotary kiln.

[0027] Step 3b: The remaining tail gas from the ring cooling section of the other ring coolers separated by the hydrogen membrane separation device is pressurized by the booster fan II and then introduced into the grate drying section for drying the unroasted pellets in the grate drying section.

[0028] Step 4: After the heat exchange in the grate drying section, the temperature of the tail gas in the grate drying section is 38°C. After being pressurized by the booster fan IV, it is introduced into the dust removal, dehydration, desulfurization and denitrification device in the tail gas external circulation section. The tail gas after simple treatment is introduced into the CO 2 Crude purification device to obtain CO 2 Gas concentration greater than 98% CO 2 gas and stored in CO 2 Gas storage cabinets for industrial pure oxygen and H 2 The gas mixture is used as fuel for roasting in the rotary kiln. Example 2

[0029] Step 1: CO in the system 2 The system runs for 28 minutes and the furnace temperature of the rotary kiln rises to 1250℃. 2 Flow rate: 25500Nm 3 / h, while H 2 Flow rate: 10500Nm 3 / h,O 2 Flow rate: 5250Nm 3 / h. The three gases are introduced into the fuel proportioning system for proportioning and mixing. The composition of the rotary kiln tail gas after roasting: 96.54 vol% CO 2 , 3.03 vol%H 2 O,0.3587 vol% H 2, flow rate is 33600 Nm 3 / h, the temperature is 620℃, and it is introduced into the preheating section of the chain grate machine to preheat the unroasted pellets in the preheating section of the chain grate machine.

[0030] Step 2: The temperature of the exhaust gas in the preheating section of the chain grate after heat exchange is 150°C, and it is introduced into the dust removal and dehydration device in the exhaust gas internal circulation section through the booster fan I. The gas composition of the treated exhaust gas is 98.87 vol% CO 2 ,0.3261 vol% H 2 , and then it is led to the ring cooling section I of the ring cooler for forced cooling of the roasted pellets and absorbing the heat of the finished pellets.

[0031] Step 3: After heat exchange in the ring cooling section I of the ring cooler, the temperature of the ring cooling tail gas of the ring cooler is 450°C. The tail gas of the ring cooling section of the ring cooler is introduced into the gas composition detection device I to analyze the H 2 concentration; then introduce the hydrogen into the hydrogen membrane separation device to separate the H 2 Gas separation.

[0032] Step 3a: Separate the H 2 After being pressurized by the booster fan III, it is introduced into the fuel proportioning system with a concentration of 99%, mixed with industrial pure oxygen and CO 2 The gas mixture is used as fuel for roasting in the rotary kiln.

[0033] Step 3b: The remaining tail gas from the ring cooling section of the other ring coolers separated by the hydrogen membrane separation device is pressurized by the booster fan II and then introduced into the grate drying section for drying the unroasted pellets in the grate drying section.

[0034] Step 4: After heat exchange in the grate drying section, the exhaust gas temperature in the grate drying section is 58°C. It is pressurized by the booster fan IV and then introduced into the dust removal, dehydration, desulfurization and denitrification device in the exhaust gas external circulation section. The exhaust gas after simple treatment is introduced into the CO 2 Crude purification device to obtain CO 2 Gas concentration greater than 98% CO 2 gas and stored in CO 2 Gas storage cabinets for industrial pure oxygen and H 2 The gas mixture is used as fuel for roasting in the rotary kiln. Example 3

[0035] A tail gas recycle O 2 -H 2 -CO 2The fuel pellet production and preparation system includes: chain grate drying section C1, chain grate preheating section C2, rotary kiln C3, ring cooler ring cooling section I C4, ring cooler ring cooling section II C5, booster fan I1, exhaust gas internal circulation section dust removal and dehydration device 2, gas composition detection device I3, hydrogen membrane separation device 4, booster fan II5, booster fan III6, fuel proportioning system 7, booster fan IV8, exhaust gas external circulation section dust removal and dehydration desulfurization and denitrification device 9, gas composition detection device II10, reversing valve I11, CO 2 Crude purification device 12, CO 2 Gas storage cabinet 13, booster fan V 14, fuel nozzle 15, feed inlet atmosphere protection device 16, annular cooler body atmosphere protection device 17.

[0036] The connection between the devices is as follows: 2 Gas, industrial pure oxygen and CO 2 The gases are connected to the fuel proportioning system 7 through pipelines P1, P2, and P3 respectively, and the hydrogen separated by the hydrogen membrane separation device 4 is 2 The gas passes through the pipeline P10, the booster fan III6 and then through the pipeline P11 to connect with the fuel proportioning system 7. The gas outlet of the fuel proportioning system 7 is connected with the fuel nozzle 15 through the pipeline P4. The lower exhaust port of the chain grate preheating section C2 is connected with the booster fan I1 through the pipeline P5. The booster fan I1 is connected with the dust removal and dehydration device 2 of the exhaust gas internal circulation section through the pipeline P6. The dust removal and dehydration device 2 of the exhaust gas internal circulation section is connected with the lower air inlet of the ring cooling section I C4 of the ring cooler through the pipeline P7. The upper exhaust port of the ring cooling section I C4 of the ring cooler is connected with the inlet of the hydrogen membrane separation device 4 through the pipeline P8. The gas composition detection device I3 is connected with the pipeline P8 through the pipeline P9. The outlet of the hydrogen membrane separation device 4 is connected with the inlet of the booster fan III6 through the pipeline P10. The outlet of the booster fan III6 is connected with the inlet of the booster fan III6 through the pipeline P1 1 is connected to the fuel proportioning system 7, the other outlet of the hydrogen membrane separation device 4 is connected to the inlet of the booster fan II5 through the pipeline P12, the outlet of the booster fan II5 is connected to the upper air inlet of the chain grate drying section C1 through the pipeline P13, the lower air outlet of the chain grate drying section C1 is connected to the air inlet of the booster fan IV8 through the pipeline P14, the air outlet of the booster fan IV8 is connected to the air inlet of the exhaust gas external circulation section dust removal, dehydration, desulfurization and denitration device 9 through the pipeline P15, the air outlet of the exhaust gas external circulation section dust removal, dehydration, desulfurization and denitration device 9 is connected to the inlet of the reversing valve I11 through the pipeline P16, the gas composition detection device II10 is connected to the pipeline P16 through the pipeline P17, one outlet of the reversing valve I11 is connected to the vent through P18 and discharged into the air, and the other outlet of the reversing valve I11 is connected to the CO 2 The inlet of the crude purification device 12 is connected to CO 2 The outlet of the crude purification device 12 is connected to the CO 2 Gas storage cabinet 13 inlet connection, CO 2The outlet of the gas storage tank 13 is connected to the inlet of the booster fan V14 through a pipeline P21, and the outlet of the booster fan V14 is connected to the fuel proportioning system 7 through a pipeline P22.

[0037] The system also includes a feed inlet atmosphere protection device 16 and a ring cooler body atmosphere protection device 17. The feed inlet atmosphere protection device 16 is installed at the head position of the chain grate machine, and the ring cooler body atmosphere protection device 17 is installed between the ring cooler ring cooling section I C4 and the ring cooling section II C5. The tail gas c of the ring cooler ring cooling section I C4 is introduced into the ring cooler body atmosphere protection device 17, and the gas blowing flow rate is adjusted according to the ambient pressure of the atmosphere protection device to protect the gas pressure at this position higher than the ambient pressure, thereby preventing air from entering the chain grate C1, C2-rotary kiln C3-ring cooler ring cooling section I C4.

[0038] Although only one practical production embodiment of the present invention is given herein, those skilled in the art should understand that the embodiments of the present invention may be modified without departing from the spirit of the present invention. The above embodiments are merely exemplary and should not be used as a limitation on the scope of the present invention.

Claims

1. A pellet production process based on tail gas recycling O2-H2-CO2 fuel, characterized in that: The process comprises the following steps: Step 1: High-temperature rotary kiln tail gas (a) generated by combustion of mixed fuel in the rotary kiln (C3) is introduced into the chain grate preheating section (C2) to preheat the unroasted pellets in the chain grate; Step 2: The low-temperature chain grate preheating section (C2) tail gas (b) generated after the heat exchange in step 1 is pressurized and introduced into the tail gas internal circulation section dust removal and dehydration device (2), and then introduced into the ring cooling section (C4) of the ring cooler to forcefully cool the roasted finished pellets; Step 3: Analyze the H2 concentration in the tail gas (c) of the ring cooling section (C4) of the ring cooler; then the tail gas is introduced into the hydrogen membrane separation device (4) to separate the H2 gas in the tail gas; Step 3a: The H2 gas separated by the hydrogen membrane separation device (4) is pressurized and introduced into the fuel proportioning system (7), and mixed with industrial pure oxygen and CO2 gas in proportion as fuel for rotary kiln roasting; Step 3b: the tail gas separated by the hydrogen membrane separation device (4) is pressurized and introduced into the grate drying section (C1) to dry the unroasted pellets; Step 4: the tail gas (d) from the grate drying section (C1) is pressurized and introduced into the tail gas external circulation section dust removal, dehydration, desulfurization and denitrification device (9), and a gas composition detection device II (10) is installed at the outlet of the equipment; Step 4a: If the CO2 gas concentration in the tail gas (d) of the grate drying section (C1) is lower than 75%, it is directly discharged into the air; Step 4b: If the CO2 gas concentration in the tail gas (d) of the grate drying section (C1) is higher than 75%, it is purified and stored, and then introduced into the fuel proportioning system (7) after being pressurized by the booster fan V (14), and mixed with industrial pure oxygen and H2 gas in proportion as fuel for rotary kiln roasting.

2. A pelletizing process based on tail gas recycling O2-H2-CO2 fuel according to claim 1, characterized in that: The ignition and heating mode of the rotary kiln is as follows: H2 gas, industrial pure oxygen and CO2 gas are mixed in proportion in the fuel proportioning system (7) and burned as the rotary kiln fuel, wherein the CO2 gas is used as the protective gas when the system equipment is working. When the furnace temperature of the rotary kiln reaches 1250°C, the pellet production process preparation operation mode remains unchanged.

3. A pellet production system based on tail gas recycling O2-H2-CO2 fuel, comprising: The invention relates to a chain grate drying section (C1), a chain grate preheating section (C2), a rotary kiln (C3), a ring cooler ring cooling section I (C4), and a ring cooler ring cooling section II (C5), characterized in that H2 gas, industrial pure oxygen, and CO2 gas are connected to a fuel proportioning system (7) through pipelines P1, P2, and P3, respectively; the H2 gas separated by the hydrogen membrane separation device (4) is connected to the fuel proportioning system (7) through pipeline P10 and booster fan III (6) and then through pipeline P11; the gas outlet of the fuel proportioning system (7) is connected to the fuel nozzle (15) through pipeline P4; the lower exhaust of the chain grate preheating section (C2) The outlet is connected to the booster fan I (1) through a pipeline P5, the booster fan I (1) is connected to the exhaust gas internal circulation section dust removal and dehydration device (2) through a pipeline P6, the exhaust gas internal circulation section dust removal and dehydration device (2) is connected to the lower air inlet of the ring cooler ring cooling section I (C4) through a pipeline P7, the upper air outlet of the ring cooler ring cooling section I (C4) is connected to the inlet of the hydrogen membrane separation device (4) through a pipeline P8, the gas composition detection device I (3) is connected to the pipeline P8 through a pipeline P9, the outlet of the hydrogen membrane separation device (4) is connected to the inlet of the booster fan III (6) through a pipeline P10, and the outlet of the booster fan III (6) is connected to the inlet of the booster fan III (6) through a pipeline P11. P11 is connected to the fuel proportioning system (7), the other outlet of the hydrogen membrane separation device (4) is connected to the inlet of the booster fan II (5) through a pipeline P12, the outlet of the booster fan II (5) is connected to the upper air inlet of the chain grate drying section (C1) through a pipeline P13, the lower air outlet of the chain grate drying section (C1) is connected to the air inlet of the booster fan IV (8) through a pipeline P14, the air outlet of the booster fan IV (8) is connected to the air inlet of the exhaust gas external circulation section dust removal, dehydration, desulfurization and denitration device (9) through a pipeline P15, and the air outlet of the exhaust gas external circulation section dust removal, dehydration, desulfurization and denitration device (9) is connected to the reversing valve I (11) through a pipeline P16. ) inlet, the gas composition detection device II (10) is connected to the pipeline P16 through the pipeline P17, one outlet of the reversing valve I (11) is connected to the vent through P18 and discharged into the air, the other outlet of the reversing valve I (11) is connected to the inlet of the CO2 crude purification device (12) through the pipeline P19, the outlet of the CO2 crude purification device (12) is connected to the inlet of the CO2 gas storage tank (13) through the pipeline P20, the outlet of the CO2 gas storage tank (13) is connected to the inlet of the booster fan V (14) through the pipeline P21, and the outlet of the booster fan V (14) is connected to the fuel proportioning system (7) through the pipeline P22.

4. A pellet production system based on tail gas recycling O2-H2-CO2 fuel according to claim 3, characterized in that: The system comprises a feed inlet atmosphere protection device (16) and a ring cooler body atmosphere protection device (17), wherein the feed inlet atmosphere protection device (16) is installed at the head of the chain grate machine, and the ring cooler body atmosphere protection device (17) is installed between the ring cooler ring cooling section I (C4) and the ring cooling section II (C5), and the tail gas (c) of the ring cooler ring cooling section I (C4) is introduced into the ring cooler body atmosphere protection device (17).

5. The pellet production and preparation system based on tail gas recycling O2-H2-CO2 fuel according to claim 3 is characterized in that: The fuel used by the rotary kiln (C3) contains: H2 gas including at least one of natural gas, shale gas, biomass cracking gas, and hydrogen; industrial pure oxygen with an oxygen concentration of ≥ 99.5 vol%; and CO2 gas with a CO2 concentration of ≥ 98 vol%.

6. The pellet production system based on tail gas recycling O2-H2-CO2 fuel according to claim 3 is characterized in that: The ring cooling section II (C5) of the ring cooler uses room temperature air as the cooling gas for the roasted finished pellets.

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