Semi-coke production system and working method thereof

Abstract

The invention relates to a semi-coke production system and a working method thereof. The semi-coke production system comprises a semi-coke oven, a dry quenching device, a combustion system, a pressure swing adsorption device, a tail gas purification device and a tail gas decarburization device, a discharging hole of the semi-coke oven is connected with a feeding hole of the dry quenching device; a gas collection tank in the semi-coke oven is sequentially connected with a tail gas purification device and a tail gas decarbonization device through a tail gas pipeline; the combustion system is composed of a plurality of combustors, and each combustor is sequentially provided with a recycled gas connector, a mixer, an oxygen connector and a CO2 connector from the tail to the head. According to the invention, nitrogen in the semicoke gas can be effectively removed, and nitrogen-free or ultralow-nitrogen gas is obtained; the content of H2 in the semicoke gas is increased to 38%-47%, and the content of CO is also remarkably increased, so that fine processing of the semicoke gas is facilitated, and the additional value of the byproduct gas is greatly increased.

Description

Technical Field

[0001] The invention relates to the technical field of low-rank coal pyrolysis and dry distillation, and in particular to a semi-coke production system and a working method thereof. Background Art

[0002] Semi-coke, also known as blue coke or upgraded coal, is a solid carbon product with low volatile matter obtained by pyrolysis of low-rank coal under high temperature or medium-low temperature conditions. Semi-coke furnace is a low-rank coal pyrolysis and distillation furnace, including high-temperature pyrolysis circular semi-coke furnace and medium-low temperature pyrolysis square semi-coke furnace. High-temperature pyrolysis circular semi-coke furnace adopts high-temperature pyrolysis process to produce coal gas, semi-coke and coal tar, and the pyrolysis temperature is 900-1200℃. Medium-low temperature pyrolysis square semi-coke furnace adopts medium-low temperature pyrolysis process to produce coal gas, semi-coke and coal tar, and the pyrolysis temperature is 600-800℃.

[0003] The coal pyrolysis and distillation process of the semi-coke oven needs to be realized through the combustion system. The use of full oxygen or oxygen-enriched combustion can greatly reduce the nitrogen content in the coal gas. However, due to the fast combustion reaction rate and strong flame propagation effect, the violent reaction will lead to the formation of local high-temperature areas in the furnace, which requires high configuration of the carbonization furnace. The conventional semi-coke oven combustion system uses air as the combustion-supporting gas, which can solve the above problems, but it leads to a large increase in nitrogen in the semi-coke tail gas (generally the nitrogen content is as high as 43% to 48%), and the nitrogen is stable in nature and is not easy to separate from the coal gas. Therefore, it is difficult to further perform high-value-added finishing on the semi-coke tail gas, which seriously affects the value of the semi-coke coal gas. Removing nitrogen from the root and reducing the generation of nitrogen oxides is a better choice.

[0004] Carbon dioxide is easily separated from the semi-coke tail gas and can replace nitrogen as a diluent gas to produce high-quality nitrogen-free coal gas. On the other hand, the technical difficulty of extracting nitrogen by pressure swing adsorption of coal gas is high. The separation coefficient of the N2-H2 system, N2-CmHn system, and N2-CO system is low, the process is difficult, and the construction cost is high; while the technology of extracting nitrogen by pressure swing adsorption of air (N2-O2 system) is relatively mature, with good separation effect and low construction cost. Summary of the invention

[0005] The present invention provides a semi-coke production system and a working method thereof, which can effectively remove nitrogen from semi-coke coal gas to obtain nitrogen-free or ultra-low nitrogen coal gas; the H2 content in the semi-coke coal gas is increased to 38% to 47%, and the CO content is also significantly improved, which is convenient for fine processing of the semi-coke coal gas, thereby greatly improving the added value of the by-product coal gas.

[0006] In order to achieve the above object, the present invention adopts the following technical solutions:

[0007] A semi-coke production system comprises a semi-coke oven, a dry coke quenching device, a combustion system, a pressure swing adsorption device, an exhaust gas purification device and an exhaust gas decarbonization device; the semi-coke oven is provided with a feed inlet at the top and a discharge inlet at the bottom, a gas collecting box is provided at the upper part of the oven, and a combustion system is provided at the lower part of the oven body; the discharge inlet of the semi-coke oven is connected to the feed inlet of the dry coke quenching device; the gas collecting box is connected to the exhaust gas purification device and the exhaust gas decarbonization device in sequence through an exhaust gas pipeline; the combustion system is composed of a plurality of burners uniformly arranged along the circumference of the semi-coke oven, and the burners are provided with a return gas interface, a mixer, an oxygen interface and a CO2 interface in sequence from the tail to the head, wherein the return gas interface is connected to the exhaust pipeline downstream of the exhaust purification device through the return gas pipeline, the oxygen interface is connected to the oxygen outlet of the pressure swing adsorption device through the oxygen pipeline, and the CO2 interface is connected to the CO2 outlet of the exhaust gas decarbonization device through the CO2 pipeline.

[0008] The feeding port of the semi-coke oven is provided with a feeding system.

[0009] An oxygen buffer tank is arranged on the oxygen pipeline downstream of the pressure swing adsorption device.

[0010] A CO2 buffer tank is provided on the CO2 pipeline downstream of the tail gas decarbonization device.

[0011] A semi-coke production system also includes a control system; the control system is composed of a DCS control system, a return gas flow regulating device, an oxygen flow regulating device and a CO2 flow regulating device; the return gas flow regulating device is arranged on the return gas pipeline upstream of the burner, the oxygen flow regulating device is arranged on the oxygen pipeline upstream of the burner, and the CO2 flow regulating device is arranged on the CO2 pipeline upstream of the burner; the return gas flow regulating device, the oxygen flow regulating device and the CO2 flow regulating device are respectively connected to the DCS control system.

[0012] The return gas flow regulating device, oxygen flow regulating device and CO2 flow regulating device all include a flow meter and a flow regulating valve.

[0013] The nitrogen-free coal gas outlet of the tail gas decarbonization device is connected to the coal gas inlet of the coal gas finishing system.

[0014] The nitrogen outlet of the pressure swing adsorption device is connected to the dry quenching cycle gas inlet of the dry quenching device through a nitrogen pipeline, or is connected to the nitrogen inlet of the synthetic ammonia unit of the coal gas finishing system through a nitrogen pipeline.

[0015] A working method of a semi-coke production system includes the following processes:

[0016] 1) Low-rank coal enters the semi-coke furnace through the feeding system, and is carbonized into semi-coke by countercurrent contact with high-temperature gas from top to bottom in the furnace. The coal gas generated during the pyrolysis and distillation of coal is mixed with the high-temperature exhaust gas entering the carbonization chamber from the combustion chamber, and enters the tail gas purification device through the gas collecting box as semi-coke tail gas to remove ammonia, tar and particulate matter, and then extracts CO2 through the tail gas decarbonization device. The purified and decarbonized nitrogen-free coal gas enters the coal gas finishing system to produce high value-added chemical products;

[0017] 2) The CO2 extracted by the tail gas decarbonization device enters the CO2 buffer tank, and then enters the burner after the flow rate is adjusted by the CO2 flow regulating device, and serves as a dilution gas for the semi-coke oven combustion-supporting gas;

[0018] 3) The pressure swing adsorption device separates oxygen and nitrogen through air PSA pressure swing adsorption. The oxygen first enters the oxygen buffer tank, and then enters the burner after the flow rate is adjusted by the oxygen flow control device; the nitrogen is supplied to the dry coke quenching device for use as dry coke quenching circulating gas, or supplied to the coal gas finishing system to produce liquid ammonia through the synthetic ammonia process;

[0019] 4) In the burner, oxygen and CO2 are mixed in a mixer and burned as combustion-supporting gas with recycled coal gas to provide heat for pyrolysis and distillation of low-rank coal;

[0020] 5) Through the DCS system, return gas flow control device, oxygen flow control device and CO2 flow control device, interlocking control of return gas, oxygen and CO2 flow is achieved to ensure that the dry distillation temperature in the semi-coke oven is within the set range and the CO2 circulation volume is guaranteed.

[0021] During the semi-coke production process, the volume ratio of O2 to CO2 is controlled at 0.2-0.5:0.8-0.5.

[0022] Compared with the prior art, the present invention has the following beneficial effects:

[0023] 1) Nitrogen in semi-coke gas can be effectively removed to obtain nitrogen-free or ultra-low nitrogen gas; the H2 content in the semi-coke gas is increased to 38% to 47%, and the CO content is also significantly increased, which is convenient for fine processing of the semi-coke gas, thereby greatly increasing the added value of the by-product gas.

[0024] 2) The semi-coke production system described in the present invention can be directly implemented without changing the existing furnace type and furnace body refractory materials, producing high-quality nitrogen-free coal gas (because the low-rank coal raw material itself contains a small amount of nitrogen, and the semi-coke furnace cannot be completely sealed, a small amount of nitrogen-containing air will enter the furnace, so the nitrogen-free coal gas described in the present invention is relatively nitrogen-free, and the nitrogen content is not zero), while reducing the coal gas consumption in the furnace;

[0025] 3) The combustion system of the semi-coke oven uses oxygen as the combustion-supporting gas and carbon dioxide as the dilution gas, which also plays a role in temperature control;

[0026] 4) The pressure swing adsorption device produces a large amount of nitrogen, which can be used as dry quenching circulating gas, and can also be fed into the coal gas finishing system to produce liquid ammonia through the synthetic ammonia process;

[0027] 5) Through the automatic control system, the flow of oxygen, carbon dioxide and recycled coal gas is flexibly adjusted to control the temperature in the furnace within the set range, while ensuring the circulation of carbon dioxide; oxygen, carbon dioxide and recycled coal gas all use a coal gas finishing system composed of a flow meter and a coal gas finishing system and are precisely controlled through a DCS system (distributed computer control system);

[0028] 6) After purification and decarbonization, the semi-coke tail gas is converted into nitrogen-free coal gas. The subsequent coal gas refining routes have many options: (1) methanation can produce liquid ammonia; (2) hydrogen refining can produce hydrogen energy; (3) conversion can be used to synthesize methanol; (4) ammonia synthesis can be used to produce liquid ammonia after hydrogen extraction. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 It is a structural schematic diagram of a semi-coke production system described in the present invention.

[0030] In the figure: 1. Semi-coke oven 2. Tail gas purification device 3. Tail gas decarbonization device 4. Coal gas finishing system 5. CO2 buffer tank 6. CO2 flow control device 7. Mixer 71. Oxygen interface 72. CO2 interface 73. Recycled coal gas interface 8. Pressure swing adsorption device 9. Oxygen buffer tank 10. Oxygen flow control device 11. Recycled coal gas flow control device 12. Feeding system 13. Gas collecting box 14. Coke dry quenching device DETAILED DESCRIPTION

[0031] The specific implementation of the present invention will be further described below in conjunction with the accompanying drawings:

[0032] like Figure 1As shown, a semi-coke production system of the present invention comprises a semi-coke oven 1, a coke dry quenching device 14, a combustion system, a pressure swing adsorption device 8, a tail gas purification device 2 and a tail gas decarbonization device 3; the semi-coke oven 1 is provided with a feed inlet at the top and a discharge outlet at the bottom, a gas collecting box 13 is provided at the upper part of the oven, and a combustion system is provided at the lower part of the oven body; the discharge outlet of the semi-coke oven 1 is connected to the feed inlet of the coke dry quenching device 14; the gas collecting box 13 is connected to the tail gas purification device 2 and the tail gas decarbonization device 4 in sequence through a tail gas pipeline; The combustion system is composed of a plurality of burners evenly arranged along the circumference of the semi-coke oven 1, and the burners are provided with a return gas interface 73, a mixer 7, an oxygen interface 71 and a CO2 interface 72 in sequence from the tail to the head, wherein the return gas interface 73 is connected to the exhaust pipeline downstream of the exhaust gas purification device 2 through a return gas pipeline, the oxygen interface 71 is connected to the oxygen outlet of the pressure swing adsorption device 8 through an oxygen pipeline, and the CO2 interface 72 is connected to the CO2 outlet of the exhaust gas decarbonization device 3 through a CO2 pipeline.

[0033] The feeding port of the semi-coke oven 1 is provided with a feeding system 12 .

[0034] An oxygen buffer tank 9 is provided on the oxygen pipeline downstream of the pressure swing adsorption device 8 .

[0035] A CO2 buffer tank 5 is provided on the CO2 pipeline downstream of the tail gas decarbonization device 3.

[0036] A semi-coke production system described in the present invention also includes a control system; the control system is composed of a DCS control system, a return gas flow regulating device 11, an oxygen flow regulating device 10 and a CO2 flow regulating device 6; the return gas flow regulating device 11 is arranged on the return gas pipeline upstream of the burner, the oxygen flow regulating device 10 is arranged on the oxygen pipeline upstream of the burner, and the CO2 flow regulating device 6 is arranged on the CO2 pipeline upstream of the burner; the return gas flow regulating device 11, the oxygen flow regulating device 10 and the CO2 flow regulating device 6 are respectively connected to the DCS control system.

[0037] The recycled coal gas flow regulating device 11, the oxygen flow regulating device 10 and the CO2 flow regulating device 6 all include flow meters and flow regulating valves.

[0038] The nitrogen-free coal gas outlet of the tail gas decarbonization device 3 is connected to the coal gas inlet of the coal gas finishing system 4 .

[0039] The nitrogen outlet of the pressure swing adsorption device 8 is connected to the dry quenching circulating gas inlet of the dry quenching device 14 through a nitrogen pipeline, or is connected to the nitrogen inlet of the synthetic ammonia unit of the coal gas finishing system 4 through a nitrogen pipeline.

[0040] A working method of a semi-coke production system includes the following processes:

[0041] 1) Low-rank coal enters the semi-coke furnace 1 through the feeding system 12, and is carbonized into semi-coke by countercurrent contact with high-temperature gas from top to bottom in the furnace. The coal gas generated during the pyrolysis and distillation of the coal is mixed with the high-temperature exhaust gas entering the carbonization chamber from the combustion chamber, and enters the tail gas purification device 2 through the gas collecting box 13 as semi-coke tail gas to remove ammonia, tar and particulate matter, and then passes through the tail gas decarbonization device 3 to extract CO2. The purified and decarbonized nitrogen-free coal gas enters the coal gas finishing system 4 to produce high value-added chemical products;

[0042] 2) CO2 extracted by the tail gas decarbonization device 3 enters the CO2 buffer tank 5, and then enters the burner after the flow rate is adjusted by the CO2 flow control device 6, and serves as a dilution gas for the combustion-supporting gas of the semi-coke oven 1;

[0043] 3) The pressure swing adsorption device 8 separates oxygen and nitrogen through air PSA pressure swing adsorption. The oxygen first enters the oxygen buffer tank 9, and then enters the burner after the flow rate is adjusted by the oxygen flow control device 10; the nitrogen is supplied to the dry coke quenching device 14 for use as dry coke quenching circulating gas, or supplied to the coal gas finishing system 4 to produce liquid ammonia through the synthetic ammonia process;

[0044] 4) In the burner, oxygen and CO2 are mixed through the mixer 7 and then burned as combustion-supporting gas with the recycled coal gas to provide heat for the pyrolysis and dry distillation of low-rank coal;

[0045] 5) Through the DCS system, the return gas flow control device 11, the oxygen flow control device 10 and the CO2 flow control device 6, the interlocking control of the return gas, oxygen and CO2 flow is realized to ensure that the carbonization temperature in the semi-coke oven is within the set range and the CO2 circulation amount is guaranteed.

[0046] During the semi-coke production process, the volume ratio of O2 to CO2 is controlled at 0.2-0.5:0.8-0.5.

[0047] The combustion system of the semi-coke oven 1 adopts the temperature control method of CO2 dilution combustion-supporting gas, which is suitable for various types of ovens and has low requirements for the configuration of the oven type. The circular semi-coke oven has high carbonization temperature, high gas output, and no return gas, and is the preferred oven type.

[0048] The feeding system 12 is used to add coal into the carbonization chamber of the semi-coke oven 1 in a timely and quantitative manner, and cooperates with the coke discharge device at the bottom of the furnace to ensure the residence time of the coal in the semi-coke oven 1 (the residence time is about 10 hours). The feeding system 12 includes: a belt conveyor, a discharge car / feeder, a feeding bin, an intermediate bin, an auxiliary coal box, a gate valve and a bin wall vibrator, etc. This is a conventional technology and will not be described in detail here.

[0049] The pressure swing adsorption device 8 is used to separate oxygen and nitrogen from the air, and includes an air compressor, a buffer tank, a deoiler, a cold dryer, a filter and a pressure swing adsorption tank, etc. This is a conventional technology and will not be elaborated here.

[0050] The tail gas purification device 2 is used for the preliminary purification of the semi-coke tail gas, and the purpose is to remove ammonia, tar, particulate matter, etc. in the semi-coke tail gas. The main equipment includes a direct cooling tower, a horizontal tube intercooling tower, an electric tar collector, a gas blower, and a gas water seal tank, etc. This is a conventional technology and will not be described in detail here.

[0051] The following examples are implemented on the premise of the technical solution of the present invention, and provide detailed implementation methods and specific operation processes, but the protection scope of the present invention is not limited to the following examples. The methods used in the following examples are conventional methods unless otherwise specified.

[0052] [Example 1]

[0053] In this embodiment, the semi-coke oven production system includes a semi-coke oven 1, an exhaust gas purification device 2, an exhaust gas decarbonization device 3, a coal gas finishing system 4, a CO2 buffer tank 5, a CO2 flow regulating device 6, a mixer 7 (including an oxygen interface 71, a CO2 interface 72 and a return gas interface 73), a pressure swing adsorption device 8, an oxygen buffer tank 9, an oxygen flow regulating device 10, a return gas flow regulating device 11, a feeding system 12, a gas collecting box 13, and a coke dry quenching device 14, etc.

[0054] A feeding system 12 is provided at the top feed port of the semi-coke oven 1 , and low-rank coal enters the carbonization chamber of the semi-coke oven 1 evenly and orderly from the top of the semi-coke oven 1 .

[0055] The coal gas generated by low-level coalification and the high-temperature exhaust gas entering the carbonization chamber from the combustion chamber, the mixed gas of the two enters the exhaust gas purification device 2 from the gas collecting box 13 as semi-coke exhaust gas, and then passes through the exhaust gas decarbonization device 3 to extract CO2, and the remaining gas enters the coal gas finishing system 4, and is processed into high value-added chemical products through hydrogen extraction.

[0056] The CO2 extracted by the tail gas decarbonization device 3 enters the CO2 buffer tank 5, and then enters the mixer 7 in the burner to mix with oxygen after the CO2 flow rate is adjusted by the CO2 flow regulating device 6. The mixed gas serves as the combustion-supporting gas of the semi-coke oven 1.

[0057] The pressure swing adsorption device 8 separates oxygen and nitrogen through air PSA pressure swing adsorption, and the nitrogen enters the dry coke quenching device 14 or the coal gas finishing system 4. The oxygen first enters the oxygen buffer tank 9, and then after the flow rate is adjusted by the oxygen flow regulating device 10, it enters the mixer 7 and CO2, and finally enters the semi-coke oven 1 as a combustion-supporting gas to be mixed with the return coal gas for combustion.

[0058] The CO2 flow regulating device 6, the oxygen flow regulating device 10 and the recycled coal gas flow regulating device 11 all include corresponding flow regulating valves and flow meters, and are interlocked and controlled through the DCS control system to flexibly adjust the ratio of CO2 and O2, as well as the flow of each gas.

[0059] The mixer 7 can be used to fully and evenly mix CO2 and O2 to avoid damage to the refractory materials in the semi-coke oven 1 due to excessive local temperature in the oven; the mixer 7 is provided with an oxygen interface 71, a CO2 interface 72 and a return gas interface 73 (some furnace types do not require return gas, and the return gas interface 73 can be cancelled accordingly).

[0060] The pressure swing adsorption device 8 is used to separate oxygen and nitrogen in the air, wherein the oxygen is supplied to the combustion system of the semi-coke oven 1 as a combustion-supporting gas, and the nitrogen is supplied to the dry coke quenching device 14 below the semi-coke oven 1 for cooling the semi-coke.

[0061] In this embodiment, the dry distillation temperature is controlled to be 750°C, the volume ratio of O2 to CO2 is 0.2:0.8, and the composition of the nitrogen-free coal gas finally obtained is shown in Table 1:

[0062] Table 1 Nitrogen-free coal gas composition (volume content, V%) and calorific value

[0063] Ingredients <![CDATA[H2]]> <![CDATA[CH4]]> CO <![CDATA[C m H n ]]> <![CDATA[N2]]> <![CDATA[O2]]> <![CDATA[Q(Kcal / Nm 3 )]]> Content (V%) 38.2 12.0 46.8 0.7 2 0.3 3517

[0064] [Example 2]

[0065] This embodiment adopts the same system and process as that of embodiment 1, and controls the volume ratio of O2 to CO2 to be 0.4:0.6. The composition of the nitrogen-free coal gas finally obtained is shown in Table 2:

[0066] Table 1 Nitrogen-free coal gas composition (volume content, V%) and calorific value

[0067] Ingredients <![CDATA[H2]]> <![CDATA[CH4]]> CO <![CDATA[C m H n ]]> <![CDATA[N2]]> <![CDATA[O2]]> <![CDATA[Q(Kcal / Nm 3 )]]> Content (V%) 39.4 13.8 43.6 0.9 2 0.3 3632

[0068] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical scheme and inventive concept of the present invention within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.

Claims

1. A semi-coke production system, characterized in that: It comprises a semi-coke oven, a dry coke quenching device, a combustion system, a pressure swing adsorption device, an exhaust gas purification device and an exhaust gas decarbonization device; the semi-coke oven is provided with a feed port on the top and a discharge port on the bottom, a gas collecting box is provided in the upper part of the oven, and a combustion system is provided in the lower part of the oven body; the discharge port of the semi-coke oven is connected with the feed port of the dry coke quenching device; the gas collecting box is connected with the exhaust gas purification device and the exhaust gas decarbonization device in sequence through an exhaust gas pipeline; the combustion system is composed of a plurality of burners uniformly arranged along the circumference of the semi-coke oven, and the burners are provided with a return gas interface, a mixer, an oxygen interface and a CO2 interface in sequence from the tail to the head, wherein the return gas interface is connected to the exhaust pipeline downstream of the exhaust purification device through the return gas pipeline, the oxygen interface is connected to the oxygen outlet of the pressure swing adsorption device through the oxygen pipeline, and the CO2 interface is connected to the CO2 outlet of the exhaust gas decarbonization device through the CO2 pipeline.

2. A semi-coke production system according to claim 1, characterized in that: The feeding port of the semi-coke oven is provided with a feeding system.

3. A semi-coke production system according to claim 1, characterized in that: An oxygen buffer tank is arranged on the oxygen pipeline downstream of the pressure swing adsorption device.

4. A semi-coke production system according to claim 1, characterized in that: A CO2 buffer tank is provided on the CO2 pipeline downstream of the tail gas decarbonization device.

5. A semi-coke production system according to claim 1, characterized in that: It also includes a control system; the control system consists of a DCS control system, a return gas flow regulating device, an oxygen flow regulating device and a CO2 flow regulating device; the return gas flow regulating device is arranged on the return gas pipeline upstream of the burner, the oxygen flow regulating device is arranged on the oxygen pipeline upstream of the burner, and the CO2 flow regulating device is arranged on the CO2 pipeline upstream of the burner; the return gas flow regulating device, the oxygen flow regulating device and the CO2 flow regulating device are respectively connected to the DCS control system.

6. A semi-coke production system according to claim 5, characterized in that: The return gas flow regulating device, oxygen flow regulating device and CO2 flow regulating device all include a flow meter and a flow regulating valve.

7. A semi-coke production system according to claim 1, characterized in that: The nitrogen-free coal gas outlet of the tail gas decarbonization device is connected to the coal gas inlet of the coal gas finishing system.

8. A semi-coke production system according to claim 1, characterized in that: The nitrogen outlet of the pressure swing adsorption device is connected to the dry quenching cycle gas inlet of the dry quenching device through a nitrogen pipeline, or is connected to the nitrogen inlet of the synthetic ammonia unit of the coal gas finishing system through a nitrogen pipeline.

9. A method for operating a semi-coke production system according to any one of claims 1 to 8, characterized in that: The process includes the following: 1) Low-rank coal enters the semi-coke furnace through the feeding system, and is carbonized into semi-coke by countercurrent contact with high-temperature gas from top to bottom in the furnace. The coal gas generated during the pyrolysis and distillation of coal is mixed with the high-temperature exhaust gas entering the carbonization chamber from the combustion chamber, and enters the tail gas purification device through the gas collecting box as semi-coke tail gas to remove ammonia, tar and particulate matter, and then extracts CO2 through the tail gas decarbonization device. The purified and decarbonized nitrogen-free coal gas enters the coal gas finishing system to produce high value-added chemical products; 2) The CO2 extracted by the tail gas decarbonization device enters the CO2 buffer tank, and then enters the burner after the flow rate is adjusted by the CO2 flow regulating device, and serves as a dilution gas for the semi-coke oven combustion-supporting gas; 3) The pressure swing adsorption device separates oxygen and nitrogen through air PSA pressure swing adsorption. The oxygen first enters the oxygen buffer tank, and then enters the burner after the flow rate is adjusted by the oxygen flow regulating device; Nitrogen is supplied to the dry coke quenching unit for use as dry coke quenching circulating gas, or supplied to the coal gas finishing system to produce liquid ammonia through the synthetic ammonia process; 4) In the burner, oxygen and CO2 are mixed in a mixer and burned as combustion-supporting gas with recycled coal gas to provide heat for pyrolysis and distillation of low-rank coal; 5) Through the DCS system, return gas flow control device, oxygen flow control device and CO2 flow control device, interlocking control of return gas, oxygen and CO2 flow is achieved to ensure that the dry distillation temperature in the semi-coke oven is within the set range and the CO2 circulation volume is guaranteed.

10. The working method of a semi-coke production system according to claim 9, characterized in that: During the semi-coke production process, the volume ratio of O2 to CO2 is controlled at 0.2-0.5:0.8-0.5.

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