Semi-coke production system

Abstract

The utility model relates to a semi-coke production system which 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. The device disclosed by the utility model can be used for effectively removing nitrogen in the semi-coke gas to obtain nitrogen-free or ultralow-nitrogen gas; 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] This utility model relates to the field of low-rank coal pyrolysis and dry distillation technology, and in particular to a semi-coke production system. Background Technology

[0002] Semi-coke, also known as semi-coke or upgraded coal, is a solid carbon product with lower volatile matter obtained by pyrolyzing low-rank coal under high or medium-low temperature conditions. A semi-coke oven is a type of low-rank coal pyrolysis and retorting furnace, including high-temperature pyrolysis round semi-coke ovens and medium-low temperature pyrolysis square semi-coke ovens. High-temperature pyrolysis round semi-coke ovens use a high-temperature pyrolysis process to produce coal gas, semi-coke, and coal tar, with a pyrolysis temperature of 900–1200℃. Medium-low temperature pyrolysis square semi-coke ovens use a medium-low temperature pyrolysis process to produce coal gas, semi-coke, and coal tar, with a pyrolysis temperature of 600–800℃.

[0003] The coal pyrolysis and dry distillation process in a semi-coke oven requires a combustion system. Using full oxygen or oxygen-enriched combustion can significantly reduce the nitrogen content in the coal gas. However, due to the rapid combustion reaction rate and strong flame propagation effect, the intense reaction can lead to localized high-temperature zones within the furnace, placing high demands on the configuration of the carbonization furnace. Conventional semi-coke oven combustion systems use air as the combustion-supporting gas, which solves the above problems, but results in a significant increase in nitrogen in the semi-coke tail gas (typically reaching 43%–48%). Furthermore, nitrogen is stable and difficult to separate from the coal gas, making further high-value-added processing of the semi-coke tail gas challenging and severely impacting its value. Removing nitrogen at its source and reducing nitrogen oxide formation is the preferred option.

[0004] Carbon dioxide is easily separated from 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 technology for extracting nitrogen from coal gas by pressure swing adsorption is technically challenging. The N2-H2 system, N2-CmHn system, and N2-CO system have low separation coefficients, high process difficulty, and high construction costs. In contrast, the technology for extracting nitrogen from air (N2-O2 system) by pressure swing adsorption is relatively mature, with good separation effect and low construction cost. Summary of the Invention

[0005] This invention provides a semi-coke production system that can effectively remove nitrogen from semi-coke gas 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 facilitates the refining of the semi-coke gas and thus greatly increases the added value of the by-product gas.

[0006] To achieve the above objectives, the present invention adopts the following technical solution:

[0007] A semi-coke production system includes a semi-coke oven, a dry quenching device, a combustion system, a pressure swing adsorption (PSA) device, a tail gas purification device, and a tail gas decarbonization device. The semi-coke oven has a feed inlet at the top and a discharge outlet at the bottom. A gas collection box is located in the upper part of the oven, and the combustion system is located in the lower part of the oven. The discharge outlet of the semi-coke oven is connected to the feed inlet of the dry quenching device. The gas collection box is connected to the tail gas purification device and the tail gas decarbonization device sequentially via tail gas pipes. The combustion system consists of multiple burners evenly arranged around the circumference of the semi-coke oven. From the tail end to the head end, each burner has a return gas inlet, a mixer, an oxygen inlet, and a CO2 inlet sequentially. The return gas inlet is connected to the tail gas pipe downstream of the tail gas purification device via a return gas pipe. The oxygen inlet is connected to the oxygen outlet of the PSA device via an oxygen pipe. The CO2 inlet is connected to the CO2 outlet of the tail gas decarbonization device via a CO2 pipe.

[0008] The semi-coke oven is equipped with a feeding system at its feed inlet.

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

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

[0011] A semi-coke production system further includes a control system; the control system comprises a DCS control system, a reflux gas flow regulating device, an oxygen flow regulating device, and a CO2 flow regulating device; the reflux gas flow regulating device is located on the reflux gas pipeline upstream of the burner, the oxygen flow regulating device is located on the oxygen pipeline upstream of the burner, and the CO2 flow regulating device is located on the CO2 pipeline upstream of the burner; the reflux 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 furnace 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 gas outlet of the tail gas decarbonization device is connected to the gas inlet of the gas refining system.

[0014] The nitrogen outlet of the pressure swing adsorption device is connected to the dry quenching circulating gas inlet of the dry quenching device via a nitrogen pipeline, or to the nitrogen inlet of the ammonia synthesis unit of the coal gas refining system via a nitrogen pipeline.

[0015] Compared with the prior art, the beneficial effects of this utility model are:

[0016] 1) It can effectively remove nitrogen from semi-coke gas to obtain nitrogen-free or ultra-low nitrogen gas; the H2 content in semi-coke gas is increased to 38% to 47%, and the CO content is also significantly increased, which facilitates the refining of semi-coke gas and thus greatly increases the added value of by-product gas.

[0017] 2) The semi-coke production system described in this utility model can be implemented directly without changing the existing furnace type and furnace body refractory material. It produces high-quality nitrogen-free coal gas (because low-rank coal raw materials themselves contain a small amount of nitrogen, and semi-coke furnaces cannot be completely sealed, a small amount of nitrogen-containing air will enter the furnace, so the nitrogen-free coal gas described in this utility model is relatively nitrogen-free, and the nitrogen content is not zero) while reducing the coal gas consumption in the furnace.

[0018] 3) The combustion system of the semi-coke oven uses oxygen as the combustion-supporting gas and carbon dioxide as the diluent gas, which also plays a role in temperature control.

[0019] 4) The pressure swing adsorption unit produces a high amount of nitrogen, which can be used as a circulating gas for dry quenching coke, or it can be fed into the coal gas refining system to produce liquid ammonia through the ammonia synthesis process.

[0020] 5) The flow rates of oxygen, carbon dioxide, and recycled gas are flexibly adjusted through the automatic control system to control the furnace temperature within the set range, while ensuring the carbon dioxide circulation rate. Oxygen, carbon dioxide, and recycled gas are all controlled by a gas refining system consisting of flow meters and a gas refining system, and precise control is achieved through a DCS system (distributed computer control system).

[0021] 6) After purification and decarbonization, semi-coke tail gas is used to obtain nitrogen-free coal gas, and there are many options for subsequent coal gas refining routes: (1) Methanation can produce liquid ammonia; (2) Hydrogen refining can produce hydrogen energy; (3) After conversion, methanol can be synthesized; (4) After hydrogen extraction, ammonia can be synthesized to produce liquid ammonia. Attached Figure Description

[0022] Figure 1 This is a schematic diagram of the structure of a semi-coke production system described in this utility model.

[0023] In the diagram: 1. Semi-coke oven 2. Tail gas purification device 3. Tail gas decarbonization device 4. Coal gas refining system 5. CO2 buffer tank 6. CO2 flow regulating device 7. Mixer 71. Oxygen interface 72. CO2 interface 73. Recycled gas interface 8. Pressure swing adsorption device 9. Oxygen buffer tank 10. Oxygen flow regulating device 11. Recycled gas flow regulating device 12. Charging system 13. Gas collection box 14. Dry quenching device Detailed Implementation

[0024] The specific embodiments of this utility model will be further described below with reference to the accompanying drawings:

[0025] like Figure 1 As shown, the semi-coke production system of this utility model includes a semi-coke oven 1, a 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 has a feed inlet at the top and a discharge outlet at the bottom. A gas collection box 13 is provided in the upper part of the oven, and a combustion system is provided in the lower part of the oven. The discharge outlet of the semi-coke oven 1 is connected to the feed inlet of the dry quenching device 14. The gas collection 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 consists of multiple burners evenly arranged around the circumference of the semi-coke oven 1. From the tail end to the head end of each burner, there are sequentially arranged a return gas inlet 73, a mixer 7, an oxygen inlet 71, and a CO2 inlet 72. The return gas inlet 73 is connected to the tail gas pipeline downstream of the tail gas purification device 2 through a return gas pipeline. The oxygen inlet 71 is connected to the oxygen outlet of the pressure swing adsorption device 8 through an oxygen pipeline. The CO2 inlet 72 is connected to the CO2 outlet of the tail gas decarbonization device 3 through a CO2 pipeline.

[0026] The semi-coke oven 1 is equipped with a feeding system 12 at its feed inlet.

[0027] An oxygen buffer tank 9 is installed on the oxygen pipeline downstream of the pressure swing adsorption device 8.

[0028] A CO2 buffer tank 5 is installed on the CO2 pipeline downstream of the exhaust gas decarbonization device 3.

[0029] The semi-coke production system of this utility model also includes a control system; the control system consists 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 located on the return gas pipeline upstream of the burner, the oxygen flow regulating device 10 is located on the oxygen pipeline upstream of the burner, and the CO2 flow regulating device 6 is located 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.

[0030] The furnace gas flow regulating device 11, oxygen flow regulating device 10, and CO2 flow regulating device 6 all include a flow meter and a flow regulating valve.

[0031] The nitrogen-free gas outlet of the tail gas decarbonization device 3 is connected to the gas inlet of the gas refining system 4.

[0032] 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 via a nitrogen pipeline, or to the nitrogen inlet of the ammonia synthesis unit of the coal gas refining system 4 via a nitrogen pipeline.

[0033] The working process of the semi-coke production system described in this utility model is as follows:

[0034] 1) Low-rank coal enters the semi-coke oven 1 through the feeding system 12. In the oven, it is carbonized into semi-coke by countercurrent contact with high-temperature gas from top to bottom. The coal gas generated during the coal pyrolysis and dry distillation process is mixed with the high-temperature waste gas entering the carbonization chamber from the combustion chamber. As semi-coke tail gas, it enters the tail gas purification device 2 through the gas collection box 13 to remove ammonia water, tar and particulate matter. Then, it passes through the tail gas decarbonization device 3 to extract CO2. The purified and decarbonized nitrogen-free coal gas enters the coal gas refining system 4 to produce high-value-added chemical products.

[0035] 2) The CO2 extracted by the tail gas decarbonization device 3 enters the CO2 buffer tank 5, and after the flow rate is adjusted by the CO2 flow rate regulating device 6, it enters the burner as a dilution gas for the combustion gas of the semi-coke oven 1.

[0036] 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 oxygen flow regulating device 10 regulates the flow rate. The nitrogen is supplied to the dry quenching device 14 as the dry quenching circulating gas, or supplied to the coal gas refining system 4 to produce liquid ammonia through the ammonia synthesis process.

[0037] 4) In the burner, oxygen and CO2 are mixed by mixer 7 and then used as combustion-supporting gas to be mixed with recycled coal gas for combustion, providing heat for the pyrolysis and dry distillation of low-rank coal.

[0038] 5) Through the DCS system, the return gas flow regulating device 11, the oxygen flow regulating device 10 and the CO2 flow regulating device 6, the interlock control of the return gas, oxygen and CO2 flow is realized to ensure that the dry distillation temperature in the semi-coke oven is within the set range, while ensuring the CO2 circulation volume.

[0039] During the semi-coke production process, the volume ratio of O2 to CO2 is controlled at 0.2-0.5:0.8-0.5.

[0040] The combustion system of semi-coke oven 1 adopts a temperature control method that uses CO2 to dilute the combustion-supporting gas, making it suitable for various oven types and requiring less stringent oven configuration. The round semi-coke oven, with its high carbonization temperature, high gas production, and absence of recycled gas, is the preferred oven type.

[0041] The feeding system 12 is used to add coal to the carbonization chamber of the semi-coke oven 1 at regular intervals and in a measured manner. In conjunction with the bottom coke discharge device, it ensures the residence time of the coal in the semi-coke oven 1 (the residence time is about 10 hours). The feeding system 12 includes: belt conveyor, unloading car / feeder, feeding hopper, intermediate hopper, auxiliary coal box, gate valve and hopper wall vibrator, etc., which are conventional technologies and will not be described in detail here.

[0042] The pressure swing adsorption unit 8 is used to separate oxygen and nitrogen from the air. It includes an air compressor, a buffer tank, an oil separator, a refrigerated dryer, a filter, and a pressure swing adsorption tank, etc. This is conventional technology and will not be described in detail here.

[0043] The exhaust gas purification device 2 is used for the preliminary purification of semi-coke exhaust gas, with the aim of removing ammonia, tar, particulate matter, etc. from the semi-coke exhaust gas. The main equipment includes a direct cooling tower, a horizontal tube indirect cooling tower, an electrostatic precipitator, a gas blower, and a gas water seal tank, etc., which are conventional technologies and will not be described in detail here.

[0044] The following embodiments are implemented based on the technical solution of this utility model, providing detailed implementation methods and specific operation processes. However, the protection scope of this utility model is not limited to the following embodiments. Unless otherwise specified, the methods used in the following embodiments are conventional methods.

[0045]

Example 1

[0046] In this embodiment, the semi-coke oven production system includes a semi-coke oven 1, a tail gas purification device 2, a tail gas decarbonization device 3, a coal gas refining 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 coal gas interface 73), a pressure swing adsorption device 8, an oxygen buffer tank 9, an oxygen flow regulating device 10, a return coal gas flow regulating device 11, a feeding system 12, a gas collecting box 13, and a dry quenching device 14, etc.

[0047] A feeding system 12 is provided at the top feed inlet 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.

[0048] The gas produced by low-rank coal oxidation and the high-temperature waste gas entering the carbonization chamber from the combustion chamber are mixed together as semi-coke tail gas and enter the tail gas purification device 2 from the gas collection box 13. After passing through the tail gas decarbonization device 3 to extract CO2, the remaining gas enters the coal gas refining system 4 to extract hydrogen and process it into high-value-added chemical products.

[0049] The CO2 extracted by the exhaust gas decarbonization device 3 enters the CO2 buffer tank 5, and after the CO2 flow rate is adjusted by the CO2 flow rate regulating device 6, it enters the mixer 7 in the burner to mix with oxygen. The mixed gas is used as the combustion gas for the semi-coke oven 1.

[0050] The pressure swing adsorption (PSA) device 8 separates oxygen and nitrogen through air PSA adsorption. The nitrogen enters the dry quenching device 14 or the gas refining system 4. The oxygen first enters the oxygen buffer tank 9, and then enters the mixer 7 to mix with CO2 after the oxygen flow regulating device 10 regulates the flow rate. Finally, it enters the semi-coke oven 1 as a combustion-supporting gas to be mixed and burned with the recycled gas.

[0051] The CO2 flow regulating device 6, the oxygen flow regulating device 10, and the return gas flow regulating device 11 all include corresponding flow regulating valves and flow meters, and are interlocked and controlled by the DCS control system to flexibly adjust the ratio of CO2 to O2 and the flow rate of each gas.

[0052] The mixer 7 can fully and evenly mix CO2 and O2, avoiding damage to the refractory materials inside the furnace due to excessively high local temperatures in the semi-coke oven 1; the mixer 7 is equipped with an oxygen inlet 71, a CO2 inlet 72 and a return gas inlet 73 (for some furnace types that do not require return gas, the return gas inlet 73 can be cancelled accordingly).

[0053] The pressure swing adsorption device 8 is used to separate oxygen and nitrogen from the air. The oxygen is sent to the combustion system of the semi-coke oven 1 as a combustion-supporting gas, and the nitrogen is supplied to the dry quenching device 14 below the semi-coke oven 1 to cool the semi-coke.

[0054] In this embodiment, the dry distillation temperature was controlled at 750℃, and the volume ratio of O2 to CO2 was 0.2:0.8. The composition of the final nitrogen-free coal gas is shown in Table 1.

[0055] Table 1. Composition (volume content, V%) and calorific value of nitrogen-free coal gas

[0056] 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

[0057]

Example 2

[0058] This embodiment uses the same system and process as Example 1, controlling the volume ratio of O2 to CO2 to be 0.4:0.6. The composition of the final nitrogen-free coal gas is shown in Table 2.

[0059] Table 1. Composition (volume content, V%) and calorific value of nitrogen-free coal gas

[0060] 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

[0061] The above description is only a preferred embodiment of the present utility model, but the protection scope of the present utility model is not limited thereto. Any equivalent substitutions or changes made by those skilled in the art within the technical scope disclosed in the present utility model, based on the technical solution and inventive concept of the present utility model, should be included within the protection scope of the present utility model.

Claims

1. A semi-coke production system, characterized by, The coke oven plant 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; the semi-coke oven is provided with a feeding port at the top and a discharging port at the bottom, and is provided with a gas collecting tank at the upper part and a combustion system at the lower part; the discharging port of the semi-coke oven is connected with the feeding port of the dry quenching device; the gas collecting tank is connected with the tail gas purification device and the tail gas decarburization device through tail gas pipelines in sequence; the combustion system is composed of a plurality of burners which are uniformly arranged along the circumference of the semi-coke oven, and the burners are provided with, from the tail end to the head, a recycled coal gas interface, a mixer, an oxygen interface and a CO2 interface in sequence, wherein the recycled coal gas interface is connected with the tail gas pipeline downstream of the tail gas purification device through a recycled coal gas pipeline, the oxygen interface is connected with the oxygen outlet of the pressure swing adsorption device through an oxygen pipeline, and the CO2 interface is connected with the CO2 outlet of the tail gas decarburization device through a CO2 pipeline.

2. A semi-char 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-char production system according to claim 1, wherein, An oxygen buffer tank is arranged on the oxygen pipeline downstream of the pressure swing adsorption device.

4. A semi-char production system according to claim 1, wherein, A CO2 buffer tank is arranged on the CO2 pipeline downstream of the tail gas decarburization device.

5. A semi-char production system according to claim 1, wherein, The control system is composed of a DCS control system, a recycled coal gas flow regulating device, an oxygen flow regulating device and a CO2 flow regulating device; the recycled coal gas flow regulating device is arranged on the recycled coal 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 recycled coal gas flow regulating device, the oxygen flow regulating device and the CO2 flow regulating device are connected with the DCS control system respectively.

6. A semi-char production system according to claim 5, wherein, The recycled coal gas flow regulating device, the oxygen flow regulating device and the CO2 flow regulating device each comprise a flow meter and a flow regulating valve.

7. A semi-char production system according to claim 1, wherein The nitrogen-free coal gas outlet of the tail gas decarburization device is connected with the coal gas inlet of a coal gas finishing system.

8. A semi-char production system according to claim 1, wherein, The nitrogen outlet of the pressure swing adsorption device is connected with the dry quenching circulating gas inlet of the dry quenching device through a nitrogen pipeline, or is connected with the nitrogen inlet of a synthetic ammonia unit of a coal gas finishing system through a nitrogen pipeline.

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