Coal oxygen-enriched self-heating pyrolysis system and method

Abstract

The application provides a coal oxygen-enriched self-heating pyrolysis system and method, and relates to the technical field of coal pyrolysis. The coal oxygen-enriched self-heating pyrolysis system comprises a pyrolysis furnace, the pyrolysis furnace comprises a furnace body, a feeding port, a discharging port and a gas outlet; the feeding port is located on one side of the furnace body; the discharging port is located on the side of the furnace body away from the feeding port; the gas outlet is located on the side of the furnace body close to the feeding port; wherein, in the direction from the feeding port to the discharging port, the pyrolysis furnace further comprises, in sequence, a preheating and primary pyrolysis zone, a main volatile analysis outlet zone, a temperature adjusting transition zone and an oxidation heat supply zone; the pyrolysis furnace further comprises a first gas inlet and a second gas inlet, the first gas inlet is in communication with the temperature adjusting transition zone, and the first gas inlet is used for introducing carbon dioxide; the second gas inlet is in communication with the oxidation heat supply zone, and the second gas inlet is used for introducing oxygen-enriched gas; and the main volatile analysis outlet zone is not provided with a gas inlet for directly introducing oxygen-enriched gas.

Description

Technical Field

[0001] This invention relates to the field of coal pyrolysis technology, specifically to a coal oxygen-enriched autothermal pyrolysis system and method. Background Technology

[0002] Coal pyrolysis can convert coal into semi-coke, tar, and coal gas, and is an important technological path for realizing the high-value utilization of coal. Traditional external heating pyrolysis relies on the furnace wall or external heat carrier for heat transfer, which has problems such as long heat transfer path, low thermal efficiency, decreased temperature uniformity inside the furnace after large-scale operation, and high overall energy consumption.

[0003] Self-heating pyrolysis introduces oxygen-containing gas into the furnace, utilizing the exothermic oxidation of some coal, semi-coke, or pyrolysis gas to sustain the reaction, thus reducing dependence on external heat sources. However, if oxygen directly enters the main pyrolysis zone, it easily reacts with volatile components such as tar vapor, methane, carbon monoxide, and hydrogen, not only reducing the yield of the target product but also easily forming localized high-temperature zones, triggering secondary cracking and temperature field fluctuations.

[0004] In related technologies, using oxygen-enriched gas can reduce the dilution of coal gas by nitrogen, which is beneficial to improving coal gas quality. However, increased oxygen concentration will further enhance the local oxidation intensity, making the contradiction between "oxidative heating" and "pyrolysis product protection" more prominent. Summary of the Invention

[0005] In view of the above problems, the present invention provides a coal oxygen-enriched autothermal pyrolysis system and method.

[0006] According to a first aspect of the present invention, a coal oxygen-enriched autothermal pyrolysis system is provided. The coal oxygen-enriched autothermal pyrolysis system includes a pyrolysis furnace, which includes a furnace body, a feed inlet, a discharge outlet, and a gas outlet. The feed inlet is located on one side of the furnace body; the discharge outlet is located on the side of the furnace body away from the feed inlet; and the gas outlet is located on the side of the furnace body near the feed inlet. In the direction from the feed inlet to the discharge outlet, the pyrolysis furnace further includes, sequentially arranged, a preheating and primary pyrolysis zone, a main volatile matter extraction zone, a temperature-regulating transition zone, and an oxidation heating zone. The pyrolysis furnace also includes a first gas inlet and a second gas inlet. The first gas inlet is connected to the temperature-regulating transition zone and is used to introduce carbon dioxide. The second gas inlet is connected to the oxidation heating zone and is used to introduce oxygen-enriched gas. The main volatile matter extraction zone does not have a gas inlet for directly introducing oxygen-enriched gas.

[0007] According to an embodiment of the present invention, the second air inlet includes at least a first sub-air inlet and a second sub-air inlet, the first sub-air inlet being disposed close to the first air inlet, and the second sub-air inlet being located on the side of the first sub-air inlet away from the first air inlet.

[0008] According to an embodiment of the present invention, the coal oxygen-enriched autothermal pyrolysis system further includes an oxygen concentration detection component and multiple temperature detection components. The oxygen concentration detection component is located between the main volatile matter extraction zone and the temperature adjustment transition zone, and the multiple temperature detection components are respectively located in the preheating and primary pyrolysis zone, the main volatile matter extraction zone, the temperature adjustment transition zone, and the oxidation heating zone.

[0009] According to an embodiment of the present invention, the coal oxygen-enriched autothermal pyrolysis system further includes a first regulating valve and a second regulating valve, wherein the first regulating valve is connected to a first air inlet and the second regulating valve is connected to a second air inlet.

[0010] According to a second aspect of the present invention, a method for coal oxygen-enriched autothermal pyrolysis based on the above-described coal oxygen-enriched autothermal pyrolysis system is provided, comprising the following steps:

[0011] Raw coal is fed into the furnace through the feed inlet. The raw coal passes through the preheating and primary pyrolysis zone and the main volatile matter analysis zone in sequence. The main volatile matter analysis zone completes the main volatile matter removal reaction to generate semi-coke and pyrolysis oil and gas. After completing at least part of the volatile matter removal reaction, the raw coal and semi-coke pass through the temperature adjustment transition zone and the oxidation heating zone in sequence. The pyrolysis oil and gas are discharged through the gas outlet.

[0012] Carbon dioxide is introduced into the temperature-controlled transition zone through the first air inlet;

[0013] Oxygen-rich gas is introduced into the oxidation heating zone through the second air inlet, so that the raw coal and / or semi-coke that have completed at least part of the volatile matter removal reaction undergo an oxidation reaction and release heat.

[0014] By adjusting the flow rates of oxygen-enriched gas and / or carbon dioxide, the volume fraction of oxygen entering the main volatile analysis zone is made less than or equal to a first threshold.

[0015] According to an embodiment of the present invention, adjusting the flow rate of oxygen-enriched gas and / or carbon dioxide to make the volume fraction of oxygen entering the main volatile analysis zone less than or equal to a first threshold includes:

[0016] When the volume fraction of oxygen entering the main volatile analysis zone is detected to be greater than the first threshold, the flow rate of oxygen-enriched gas introduced into the second inlet is reduced, and / or the flow rate of carbon dioxide introduced into the first inlet is increased, so that the volume fraction of oxygen entering the main volatile analysis zone is less than or equal to the first threshold.

[0017] According to an embodiment of the present invention, the second air inlet includes at least a first sub-air inlet and a second sub-air inlet, the first sub-air inlet being disposed close to the first air inlet, and the second sub-air inlet being located on the side of the first sub-air inlet away from the first air inlet. The coal oxygen-enriched autothermal pyrolysis method further includes:

[0018] When the volume fraction of oxygen entering the main volatile analysis zone is detected to be greater than the first threshold, the flow rate of oxygen-enriched gas introduced into the first sub-inlet is reduced, or oxygen-enriched gas is introduced into the oxidation heating zone only through the second sub-inlet, so that the volume fraction of oxygen entering the main volatile analysis zone is less than or equal to the first threshold.

[0019] According to embodiments of the present invention, the coal oxygen-enriched autothermal pyrolysis method includes at least one of a high effective gas operation mode, a tar protection operation mode, and a high semi-coke yield operation mode, wherein:

[0020] When the coal oxygen-enriched autothermal pyrolysis system operates in the high effective gas mode, the temperature of the oxidation heating zone and the amount of carbon dioxide introduced are increased, so that at least part of the high-temperature semi-coke reacts with carbon dioxide to generate carbon monoxide, which is then discharged through the gas outlet.

[0021] When the coal oxygen-enriched autothermal pyrolysis system is operating in tar protection mode, the oxygen distribution ratio of the first sub-inlet is reduced so that oxygen is mainly introduced through the second sub-inlet.

[0022] When the coal oxygen-enriched autothermal pyrolysis system operates in a high semi-coke yield mode, the amount of oxygen-enriched gas and / or carbon dioxide introduced should be reduced to decrease the degree of further oxidation and gasification of the semi-coke, while maintaining the stable autothermal operation of the coal oxygen-enriched autothermal pyrolysis system.

[0023] According to an embodiment of the present invention, the first threshold is greater than or equal to 0.2% and less than or equal to 1.0%.

[0024] According to an embodiment of the present invention, the volume fraction of oxygen in the oxygen-enriched gas is 30% to 100%, and the oxygen injection rate is 0.05 to 0.60 Nm³ per unit dry coal mass. 3 / kg, the carbon dioxide injection rate is 0.02~1.00 Nm 3 / kg.

[0025] The coal oxygen-enriched autothermal pyrolysis system provided by this invention has at least the following beneficial effects:

[0026] (1) By spatially separating the main volatile matter separation zone and the oxidation heating zone in the furnace, the oxygen-enriched gas can preferentially contact the coal or semi-coke that has completed the main volatile matter removal reaction and undergo oxidation reaction, thereby reducing the direct oxidation of pyrolysis oil and gas by oxygen and increasing the yield of pyrolysis oil and gas.

[0027] (2) At least part of the heat generated by the oxidation of semi-coke can be transferred to the upper pyrolysis zone to achieve self-heating and reduce dependence on external heating.

[0028] (3) By setting up a temperature-regulating transition zone between the oxidation heating zone and the main volatile matter separation zone, the carbon dioxide introduced from the first air inlet can be mixed with the high-temperature gas transferred upward from the oxidation heating zone, thereby achieving local high-temperature peak reduction and heat transport, and thus achieving heat self-balance in the pyrolysis process.

[0029] (4) Carbon dioxide can also react with high-temperature semi-coke to produce carbon monoxide, thereby increasing the proportion of effective gas in pyrolysis gas. Attached Figure Description

[0030] The above and other objects, features and advantages of the present invention will become more apparent from the following description of embodiments of the invention with reference to the accompanying drawings, in which:

[0031] Figure 1 A schematic diagram of a coal oxygen-enriched autothermal pyrolysis system according to an embodiment of the present invention is shown.

[0032] Figure 2 A flowchart illustrating a coal oxygen-enriched autothermal pyrolysis method according to an embodiment of the present invention is shown. Detailed Implementation

[0033] To make the objectives, technical solutions, and advantages of the present invention clearer, the present invention will be further described in detail below with reference to specific embodiments and accompanying drawings.

[0034] Figure 1 A schematic diagram of a coal oxygen-enriched autothermal pyrolysis system according to an embodiment of the present invention is shown.

[0035] like Figure 1 As shown, the coal oxygen-enriched autothermal pyrolysis system includes a pyrolysis furnace 100. The pyrolysis furnace 100 includes a furnace body 11, a feed inlet 12, a discharge outlet 13, and a gas outlet 14. The feed inlet 12 is located on one side of the furnace body 11, for example, at the top of the furnace body 11. Raw coal enters the furnace through the feed inlet 12 for pyrolysis. The discharge outlet 13 is located on the side of the furnace body 11 away from the feed inlet 12, for example, at the bottom of the furnace body 11. The semi-coke generated after the raw coal pyrolysis is discharged from the discharge outlet 13. The gas outlet 14 is located on the side of the furnace body 11 closer to the feed inlet 12, for example, the gas outlet 14 is also located at the top of the furnace body 11. The pyrolysis oil and gas generated after the raw coal pyrolysis is discharged from the gas outlet 14.

[0036] Reference Figure 1Along the direction from the feed inlet 12 to the discharge outlet 13 (i.e., the X direction), the pyrolysis furnace 100 also includes a preheating and primary pyrolysis zone 21, a main volatile matter extraction zone 22, a temperature-regulating transition zone 23, and an oxidation heating zone 24, arranged sequentially. It can be understood that after the raw coal enters the furnace, it first passes through the preheating and primary pyrolysis zone 21, where it undergoes preheating and primary pyrolysis. It then enters the main volatile matter extraction zone 22, where the main volatile matter removal reaction is completed in a basically oxygen-free or low-oxygen environment, generating semi-coke and pyrolysis oil and gas. The pyrolysis oil and gas can be discharged through the gas outlet 14. After completing the main volatile matter removal reaction, the coal or semi-coke further enters the oxidation heating zone 24.

[0037] Reference Figure 1 The pyrolysis furnace 100 also includes a first air inlet 31 and a second air inlet 32. The first air inlet 31 is connected to the temperature-regulating transition zone 23 and is used to introduce carbon dioxide. The second air inlet 32 ​​is connected to the oxidation heating zone 24 and is used to introduce oxygen-enriched gas. The main volatile matter extraction zone 22 does not have an air inlet for directly introducing oxygen-enriched gas. It can be understood that the oxygen-enriched gas introduced through the second air inlet 32 ​​undergoes an oxidation reaction after contacting coal or semi-coke in the oxidation heating zone 24, releasing heat and forming high-temperature gases including carbon monoxide and carbon dioxide. The released heat is transferred to the temperature-regulating transition zone 23, the main volatile matter extraction zone 22, and the preheating and primary pyrolysis zone 21 through solid-state heat transfer and the upward-moving high-temperature gas, providing energy for the drying and pyrolysis of the upper coal material, thus achieving self-heating and reducing dependence on external heating. Because oxygen-enriched gas preferentially contacts and oxidizes coal or semi-coke that has already undergone major volatile matter removal reactions, it reduces the direct oxidation of pyrolysis oil and gas by oxygen, thereby increasing the yield of pyrolysis oil and gas. Carbon dioxide introduced through the first inlet 31 mixes with the high-temperature gas transferred upwards from the oxidation heating zone 24 in the temperature-regulating transition zone 23, buffering the localized high temperatures generated by oxygen-enriched oxidation and achieving heat self-balance in the pyrolysis process. Furthermore, carbon dioxide can also undergo a gasification reaction with the high-temperature semi-coke to generate carbon monoxide, thereby increasing the proportion of effective gas in the pyrolysis gas.

[0038] It should be noted that in this embodiment, carbon dioxide and oxygen-enriched gas use independent gas supply pipelines and are not premixed before entering the pyrolysis furnace 100. During the start-up phase of the pyrolysis furnace 100, the coal inside the furnace is first subjected to initial pyrolysis through external heating, forming a high-temperature coal and / or semi-coke layer in the oxidation heating zone 24. Subsequently, carbon dioxide is introduced first, and after the carbon dioxide gas flow stabilizes, oxygen-enriched gas is gradually introduced. Once the partial oxidation reaction in the oxidation heating zone 24 can provide the heat required for the pyrolysis process, the oxygen-enriched gas and carbon dioxide are continuously supplied, and the pyrolysis furnace 100 enters a stable self-heating operation state.

[0039] In some embodiments, the temperature of the preheating and primary pyrolysis zone 21 can be 100~450°C. The temperature of the main volatile matter separation zone 22 can be 400~700°C. The temperature of the temperature-adjusting transition zone 23 can be 550~800°C. The temperature of the oxidation heating zone 24 can be 600~950°C.

[0040] It should be noted that the temperatures in each of the above zones refer to the furnace temperature during the actual operation of the pyrolysis furnace 100. During the start-up phase, the pyrolysis furnace 100 primarily uses external heating to bring the coal to its initial pyrolysis temperature. As oxygen-enriched gas is introduced into the oxidation heating zone 24, some of the coal and / or semi-coke undergo oxidation and release heat, gradually replacing the external heating. During the stable operation phase, the pyrolysis furnace 100 uses the partial oxidation heat release from the oxidation heating zone 24 as the primary heat source, with external heating only used for start-up or necessary auxiliary heating.

[0041] In some embodiments, the average temperature of the main volatile matter extraction zone 22 is preferably controlled at 500~700°C. The equivalent heating rate of the coal in the main volatile matter extraction zone 22 can be 1~50°C / min, preferably 2~30°C / min. The maximum temperature of the oxidation heating zone 24 is preferably controlled below 850°C.

[0042] In some embodiments, the carbon dioxide injection rate can be 0.02~1.00 Nm³ per unit dry coal mass. 3 / kg. That is, for every 1 kg of raw coal input, 0.02~1.00 standard cubic meters of carbon dioxide need to be introduced. Preferably, the carbon dioxide introduction rate is 0.05~0.60 Nm³. 3 / kg. By adjusting the amount of carbon dioxide introduced, the heat generated in the oxidation heating zone 24 can be transferred to the main volatile matter extraction zone 22 in a controlled manner.

[0043] In some embodiments, the volume fraction of oxygen in the oxygen-enriched gas can be 30% to 100%, preferably 50% to 100%, and more preferably 80% to 100%. The oxygen flow rate per unit dry coal mass can be 0.05 to 0.60 Nm³. 3 / kg. This means that for every 1 kg of raw coal input, 0.05~0.60 standard cubic meters of oxygen are required. Preferably, the oxygen input rate is 0.10~0.50 Nm³. 3 / kg. In the actual pyrolysis process, the oxygen flow rate can be adjusted according to the coal type, moisture content, volatile matter content, heat loss of the pyrolysis furnace 100, and the distribution of the target product.

[0044] In some embodiments, the second air inlet 32 ​​includes at least a first sub-air inlet 321 and a second sub-air inlet 322. The first sub-air inlet 321 is located close to the first air inlet 31, and the second sub-air inlet 322 is located on the side of the first sub-air inlet 321 away from the first air inlet 31. That is, along the X direction, at least two sub-air inlets are provided for introducing oxygen-enriched gas, and both can be opened or partially opened according to actual needs.

[0045] In some embodiments, the coal oxygen-enriched autothermal pyrolysis system further includes an oxygen concentration detection component 41 and multiple temperature detection components 42. The oxygen concentration detection component 41 is located between the main volatile matter extraction zone 22 and the temperature adjustment transition zone 23, and is used to detect the oxygen concentration in the gas entering the main volatile matter extraction zone 22 from the oxidation heating zone 24. The multiple temperature detection components 42 are respectively located in the preheating and primary pyrolysis zone 21, the main volatile matter extraction zone 22, the temperature adjustment transition zone 23, and the oxidation heating zone 24, and are used to detect the temperatures of the preheating and primary pyrolysis zone 21, the main volatile matter extraction zone 22, the temperature adjustment transition zone 23, and the oxidation heating zone 24. It should be noted that... Figure 1 The illustration only takes the temperature detection component 42 set in the main volatile analysis zone 22 as an example.

[0046] In some embodiments, the coal oxygen-enriched autothermal pyrolysis system further includes a first regulating valve 51 and a second regulating valve 52. The first regulating valve 51 is connected to a first air inlet 31 and is used to regulate the flow rate of gas introduced through the first air inlet 31, for example, to regulate the flow rate of carbon dioxide introduced through the first air inlet 31. The second regulating valve 52 is connected to a second air inlet 32 ​​and is used to regulate the flow rate of gas introduced through the second air inlet 32, for example, to regulate the flow rate of oxygen-enriched gas introduced through the second air inlet 32.

[0047] For example, refer to Figure 1 The coal oxygen-enriched autothermal pyrolysis system may include at least two second regulating valves 52. The at least two second regulating valves 52 respectively control the first sub-inlet 321 and the second sub-inlet 322. That is, the first sub-inlet 321 and the second sub-inlet 322 can be opened and closed independently, and the flow rate of the oxygen-enriched gas can be adjusted independently. In actual use, at least one of the first sub-inlet 321 and the second sub-inlet 322 can be opened to supply oxygen according to different coal types, processing capacities, and the position of the pyrolysis reaction front.

[0048] For example, refer to Figure 1 The coal oxygen-enriched autothermal pyrolysis system may also include a control unit 400, which can acquire data from the oxygen concentration detection component 41 and the temperature detection component 42, and control the first regulating valve 51 and the second regulating valve 52 respectively based on the acquired data.

[0049] It is understood that pyrolysis oil and gas mainly consist of tar vapor and coal gas. In some embodiments, the coal oxygen-enriched autothermal pyrolysis system may further include a gas-solid separation component 200 and a condensation separation component 300. The inlet of the gas-solid separation component 200 is connected to the gas outlet 14 of the pyrolysis furnace 100, and the outlet of the gas-solid separation component 200 is connected to the inlet of the condensation separation component 300. After passing through the gas-solid separation component 200, solid particles such as coal powder and semi-coke dust mixed in with the pyrolysis oil and gas can be removed, thereby purifying the pyrolysis oil and gas. After purification, the pyrolysis oil and gas is cooled by the condensation separation component 300, causing the tar with a higher boiling point to condense from the gaseous state into a liquid state and be discharged from the first outlet 301 of the condensation separation component 300, while the coal gas with a lower boiling point remains in a gaseous state and is discharged from the second outlet 302 of the condensation separation component 300, thereby achieving the separation of tar and coal gas.

[0050] Figure 2 A flowchart illustrating a coal oxygen-enriched autothermal pyrolysis method according to an embodiment of the present invention is shown.

[0051] Combined with reference Figure 1 and Figure 2 The coal oxygen-enriched autothermal pyrolysis method based on the above-mentioned coal oxygen-enriched autothermal pyrolysis system includes steps S1 to S4.

[0052] In step S1, raw coal is fed into the furnace body 11 through the feed inlet 12. The raw coal passes through the preheating and primary pyrolysis zone 21 and the main volatile matter analysis zone 22 in sequence. The main volatile matter removal reaction is completed in the main volatile matter analysis zone 22 to generate semi-coke and pyrolysis oil and gas. After completing at least part of the volatile matter removal reaction, the raw coal and semi-coke pass through the temperature adjustment transition zone 23 and the oxidation heating zone 24 in sequence. The pyrolysis oil and gas are discharged through the gas outlet 14.

[0053] Step S2: Carbon dioxide is introduced into the temperature-adjusting transition zone 23 through the first air inlet 31.

[0054] In step S3, oxygen-enriched gas is introduced into the oxidation heating zone 24 through the second air inlet 32, so that the raw coal and / or semi-coke that have completed at least part of the volatile matter removal reaction undergo an oxidation reaction and release heat.

[0055] Step S4: By adjusting the flow rate of oxygen-enriched gas and / or carbon dioxide, the volume fraction of oxygen entering the main volatile analysis zone 22 is less than or equal to the first threshold.

[0056] Understandably, in this embodiment, carbon dioxide is introduced first, followed by oxygen-enriched gas. The high-temperature gas generated by the reaction of the oxygen-enriched gas with the semi-coke can be buffered by the carbon dioxide, preventing the formation of localized high-temperature zones. By adjusting the flow rates of the oxygen-enriched gas and / or carbon dioxide, the volume fraction of oxygen entering the main volatile analysis zone 22 can be made less than or equal to a first threshold, ensuring that the main volatile analysis zone 22 is in an environment with essentially no or low free oxygen. This reduces the direct oxidation of pyrolysis oil and gas by oxygen and improves the yield of pyrolysis oil and gas.

[0057] In some embodiments, the first threshold is greater than or equal to 0.2% and less than or equal to 1.0%. For example, by adjusting the flow rate of oxygen-enriched gas and / or carbon dioxide, the volume fraction of oxygen in the gas entering the main volatile matter extraction zone 22 is 0-1.0%, preferably 0-0.5%, and more preferably 0-0.2%. This causes oxygen to be mainly consumed in the temperature-adjusting transition zone 23 and the oxidation heating zone 24, thereby forming the oxidation reaction boundary AA. The main volatile matter extraction zone 22 is located outside the oxidation reaction boundary AA, which can maintain a low residual oxygen environment and reduce the degree of direct oxidation of tar vapor and pyrolysis gas components such as H2, CO, and CH4.

[0058] It should be noted that the raw coal fed into the furnace is crushed and screened coal particles. For example, the particle size of the raw coal can be 3-50 mm. Preferably, the particle size of the raw coal can be 5-30 mm. The raw coal can be lignite, long-flame coal, non-caking coal, weakly caking coal, gas coal, or other coal types suitable for medium- and low-temperature pyrolysis. Depending on the moisture content of the raw coal, it can be pre-dried before entering the pyrolysis furnace 100.

[0059] In some embodiments, the total residence time of the coal in the pyrolysis furnace 100 can be 20 to 240 minutes, preferably 30 to 150 minutes. The operating pressure of the pyrolysis furnace 100 can be atmospheric pressure to 0.50 MPa gauge pressure, preferably atmospheric pressure to 0.20 MPa gauge pressure.

[0060] In some embodiments, step S4 includes: when the volume fraction of oxygen entering the main volatile analysis zone 22 is detected to be greater than a first threshold, reducing the flow rate of oxygen-enriched gas entering the second inlet 32, and / or increasing the flow rate of carbon dioxide entering the first inlet 31, so that the volume fraction of oxygen entering the main volatile analysis zone 22 is less than or equal to the first threshold. It is understood that the oxygen concentration detection component 41 located between the temperature transition zone 23 and the main volatile analysis zone 22 can detect the volume fraction of oxygen in the gas entering the main volatile analysis zone 22 in real time. When the volume fraction of oxygen is detected to be greater than the first threshold (i.e., a set value), the control unit 400 can control the opening degree of the second regulating valve 52 to reduce the flow rate of oxygen-enriched gas entering the second inlet 32, thereby reducing the volume fraction of oxygen. The control unit 400 can also control the opening degree of the first regulating valve 51 to increase the flow rate of carbon dioxide entering the first inlet 31, thereby diluting the gas entering the main volatile analysis zone 22 and reducing the volume fraction of oxygen.

[0061] In some embodiments, the second air inlet 32 ​​includes at least a first sub-air inlet 321 and a second sub-air inlet 322. The first sub-air inlet 321 is located close to the first air inlet 31, and the second sub-air inlet 322 is located on the side of the first sub-air inlet 321 away from the first air inlet 31. The coal oxygen-enriched autothermal pyrolysis method further includes: when the volume fraction of oxygen entering the main volatile matter analysis zone 22 is detected to be greater than a first threshold, reducing the flow rate of oxygen-enriched gas introduced into the first sub-air inlet 321, or introducing oxygen-enriched gas only through the second sub-air inlet 322 into the oxidation heating zone 24, so that the volume fraction of oxygen entering the main volatile matter analysis zone 22 is less than or equal to the first threshold. Understandably, when the volume fraction of oxygen detected is greater than the first threshold (i.e. the set value), the control unit 400 can reduce the flow rate of oxygen-enriched gas into the first sub-inlet 321 by controlling the second regulating valve 52, or introduce oxygen-enriched gas into the oxidation heating zone 24 only through the second sub-inlet 322, thereby shifting the oxidation reaction boundary AA downward to reduce the volume fraction of oxygen entering the main volatile matter separation zone 22.

[0062] In some embodiments, the coal oxygen-enriched autothermal pyrolysis method includes at least one of a high effective gas operation mode, a tar protection operation mode, and a high semi-coke yield operation mode. Specifically: when the coal oxygen-enriched autothermal pyrolysis system operates in the high effective gas operation mode, the temperature of the oxidation heating zone 24 and the carbon dioxide injection rate are increased, causing at least a portion of the high-temperature semi-coke to undergo a gasification reaction with carbon dioxide, generating carbon monoxide, which is then discharged through the outlet 14; when the coal oxygen-enriched autothermal pyrolysis system operates in the tar protection operation mode, the oxygen distribution ratio at the first sub-inlet 321 is reduced, allowing oxygen to be mainly introduced through the second sub-inlet 322; when the coal oxygen-enriched autothermal pyrolysis system operates in the high semi-coke yield operation mode, while maintaining stable autothermal operation of the coal oxygen-enriched autothermal pyrolysis system, the injection rate of oxygen-enriched gas and / or carbon dioxide is reduced to decrease the degree of further oxidation and gasification of the semi-coke.

[0063] Understandably, in the high-effective-gas operation mode, increasing the carbon dioxide injection rate and the temperature of the oxidation heating zone 24 can promote the endothermic gasification reaction between carbon dioxide and high-temperature semi-coke, generating carbon monoxide. This increases the carbon monoxide content in the pyrolysis gas, i.e., the proportion of effective gas in the pyrolysis gas. For example, the carbon dioxide injection rate can be 0.30~0.60 Nm³. 3 / kg. The temperature in the oxidative heating zone 24 can be 700~850℃.

[0064] In the tar protection operation mode, by reducing the oxygen distribution ratio of the first sub-inlet 321, more oxygen is introduced through the lower-positioned second sub-inlet 322. This allows the main oxidation reaction to shift towards the lower part of the furnace body 11, reducing the contact between newly generated tar vapor and oxygen. For example, the oxygen flow distribution ratio of the first sub-inlet 321 and the second sub-inlet 322 is 35:65. When the oxygen concentration entering the main volatile matter separation zone 22 increases, the oxygen ratio of the first sub-inlet 321 can be further reduced from 35% until the first sub-inlet 321 is closed, allowing all oxygen to be supplied through the lower-positioned second sub-inlet 322.

[0065] In the high semi-coke yield operation mode, by reducing the flow rate of oxygen-enriched gas and / or carbon dioxide while maintaining stable self-heating operation of the coal oxygen-enriched autothermal pyrolysis system, and appropriately lowering the temperature of the oxidation heating zone 24, the further oxidation of semi-coke and the carbon loss caused by its gasification reaction with carbon dioxide can be reduced while maintaining the system's thermal balance. For example, it is preferable to control the carbon dioxide flow rate at 0.02~0.10 Nm³ / kg, with the minimum oxygen-enriched gas flow rate controlled to maintain stable self-heating operation of the pyrolysis furnace 100. That is, through the coordinated adjustment of oxygen-enriched gas flow rate, carbon dioxide flow rate, oxygen supply location, and furnace temperature, the directional control of the three-phase products of semi-coke, tar, and coal gas can be achieved.

[0066] It should be noted that the "effective gas concentration" referred to in this article is the sum of the volume fractions of H2, CO and CH4 in dry-basis pyrolysis gas.

[0067] It should be noted that oxygen and CO2 enter the pyrolysis furnace 100 through independent pipelines. In the specific operating conditions used for performance evaluation in Tables 1 and 2 (described later), the CO2 feed rate is 0.25 Nm³ / kg and the oxygen feed rate is 0.26 Nm³ / kg per unit dry coal mass. The oxygen flow rates at the first sub-inlet 321 and the second sub-inlet 322 are allocated in a 35:65 ratio. Unless otherwise specified, the basic operating conditions, such as raw coal, coal particle size, feed rate, residence time, and temperature of the main volatile matter extraction zone 22, remain consistent in the following embodiments and comparative examples.

[0068] The following detailed description of the coal oxygen-enriched autothermal pyrolysis method provided by the present invention is based on specific embodiments.

[0069] Reference Figure 1 In Embodiment 1 of this invention, a vertical moving bed pyrolysis furnace 100 is used to process raw coal with a particle size of 6-20 mm. The raw coal is continuously added from the top of the pyrolysis furnace 100 and sequentially passes through a preheating and primary pyrolysis zone 21, a main volatile matter extraction zone 22, a temperature-regulating transition zone 23, and an oxidation heating zone 24. The temperature of the main volatile matter extraction zone 22 is controlled at 550-650°C. Carbon dioxide is independently introduced into the temperature-regulating transition zone 23, and the amount of carbon dioxide introduced is controlled at 0.10-0.40 Nm³ per unit dry coal mass. 3 / kg. Two independent oxygen supply ports (i.e., the first sub-inlet 321 and the second sub-inlet 322) are set up in the oxidation heating zone 24, using oxygen-enriched gas with an oxygen volume fraction greater than 90% as the oxidation medium. The oxygen flow rate is controlled at 0.20~0.45 Nm³ per unit dry coal mass. 3 / kg. Oxygen and CO2 enter the reactor through separate pipelines.

[0070] In Example 1, the residual oxygen concentration in the gas entering the main volatile analysis zone 22 is detected by an oxygen concentration detection component 41 located between the temperature transition zone 23 and the main volatile analysis zone 22. By adjusting the oxygen supply, the volume fraction of oxygen in the gas entering the main volatile analysis zone 22 is less than or equal to 0.5%.

[0071] In Comparative Example 1, the same vertical moving bed pyrolysis furnace 100, raw coal, coal particle size, feed rate, and residence time as in Example 1 were used. The temperature of the main volatile matter extraction zone 22 was controlled at 550~650℃. The carbon dioxide injection rate was controlled at 0.20 Nm³ per unit dry coal mass. 3 / kg, the oxygen flow rate is controlled at 0.26 Nm³. 3 / kg. Oxygen and carbon dioxide are pre-mixed to form a mixed gas before entering the pyrolysis furnace 100, and enter the pyrolysis furnace 100 through the first sub-inlet 321. In this comparative example, carbon dioxide is not independently introduced into the temperature-regulating transition zone 23, thus the temperature-regulating transition function composed of independent CO2 supply is not formed. Oxygen and carbon dioxide are pre-mixed before entering the pyrolysis furnace 100 and are centrally supplied through the first sub-inlet 321, allowing the oxygen-containing mixed gas to migrate directly to the main volatile matter separation zone 22.

[0072] In Comparative Example 2, the same vertical moving bed pyrolysis furnace 100, raw coal, coal particle size, feed rate, and residence time as in Example 1 were used. The temperature of the main volatile matter extraction zone 22 was controlled at 550~650℃. The oxygen injection rate was controlled at 0.26 Nm³ per unit dry coal mass. 3 / kg. In this comparative example, oxygen is introduced through the second sub-inlet 322, and carbon dioxide is not introduced.

[0073] The data on residual oxygen concentration entering the main volatile matter analysis zone 22, maximum temperature of the oxidation heating zone 24, tar yield, and effective gas concentration in pyrolysis gas, tested by Example 1, Comparative Example 1, and Comparative Example 2 respectively, are shown in Table 1 below.

[0074] Table 1

[0075]

[0076] As shown in Table 1, under the conditions of stratified oxygen supply and independent supply of CO2 and oxygen-enriched gas in separate zones in Example 1, the residual oxygen concentration entering the main volatile matter extraction zone 22 decreased, the maximum temperature of the oxidation heating zone 24 decreased, and the tar yield and effective gas concentration in the pyrolysis gas increased. These results indicate that spatially separating the oxidation heating zone 24 from the main volatile matter extraction zone 22, and using CO2 in the temperature-regulating transition zone 23 to regulate and dilute the upward-transmitted high-temperature oxygen-containing gas, helps reduce the degree of oxygen entering the main volatile matter extraction zone 22, alleviates localized high temperatures, and reduces direct oxidation losses of the pyrolysis oil and gas.

[0077] In Embodiment 2 of the present invention, based on Embodiment 1, the carbon dioxide injection rate is adjusted to 0.10 Nm³. 3 / kg.

[0078] In Embodiment 3 of the present invention, based on Embodiment 1, the first sub-inlet 321 is closed, and the second sub-inlet 322, located at a lower position, is opened. This increases the axial distance between the oxidation reaction zone and the main volatile matter removal zone 22. When the furnace throughput decreases or the main volatile matter removal reaction zone shifts upward, the first sub-inlet 321 can be reopened. In other words, the effective oxygen supply position can be changed according to the pyrolysis reaction front.

[0079] The data on the residual oxygen concentration entering the main volatile analysis zone 22, the maximum temperature of the oxidation heating zone 24, and the effective gas concentration in the pyrolysis gas, which were tested in Examples 1, 2, and 3 respectively, are shown in Table 2 below.

[0080] Table 2

[0081]

[0082] As shown in Table 2, under the condition that the oxygen distribution between the first sub-inlet 321 and the second sub-inlet 322 remains at 35:65, in Example 1, after increasing the CO2 input rate from 0.10 Nm³ / kg in Example 2 to 0.25 Nm³ / kg, the residual oxygen volume fraction entering the main volatile matter separation zone 22 decreased from 0.45% to 0.30%, the maximum temperature of the oxidation heating zone 24 decreased from 795℃ to 760℃, and the effective gas concentration in the pyrolysis gas increased from 53.62 vol% to 61.27 vol%. This indicates that appropriately increasing the CO2 input rate in the temperature adjustment transition zone 23 is beneficial for reducing the oxygen concentration in the upward migrating gas and buffering the local high temperature in the oxidation heating zone 24, while also promoting the gasification reaction between the high-temperature semi-coke and CO2.

[0083] In Example 3, while maintaining the same CO2 injection rate as in Example 1, the first sub-inlet 321, located near the main volatile matter extraction zone 22, was closed, allowing all oxygen-enriched gas to be supplied through the lower-positioned second sub-inlet 322. Compared to Example 1, the residual oxygen volume fraction further decreased from 0.30% to 0.18%, and the maximum temperature of the oxidation heating zone 24 decreased from 760°C to 745°C. This indicates that further lowering the location of the main oxidation reaction increases the axial distance between the oxidation reaction zone and the main volatile matter extraction zone 22, thereby further reducing the degree of oxygen migration to the main volatile matter extraction zone 22.

[0084] Meanwhile, the effective gas concentration in Example 3 decreased from 61.27 vol% to 58.70 vol%, indicating that while further lowering the oxygen supply position is beneficial for enhancing tar protection and reducing residual oxygen, it may alter the degree of CO2 gasification and coal gasification reactions in the high-temperature zone. Therefore, the oxygen distribution ratio of the first sub-inlet 321 and the second sub-inlet 322 can be adjusted according to objectives such as tar protection, effective gas yield, and furnace temperature field.

[0085] The embodiments of the present invention have been described above. However, these embodiments are merely illustrative and not intended to limit the scope of the invention. Although various embodiments have been described above, this does not mean that the measures in the various embodiments cannot be used advantageously in combination. The scope of the invention is defined by the appended claims and their equivalents. Various substitutions and modifications can be made by those skilled in the art without departing from the scope of the invention, and all such substitutions and modifications should fall within the scope of the invention.

Claims

1. A coal oxygen-enriched self-heating pyrolysis system, characterized in that, The coal oxygen-enriched autothermal pyrolysis system includes a pyrolysis furnace, which comprises: Furnace body; The feed inlet is located on one side of the furnace body; The discharge port is located on the side of the furnace body away from the feed port; and The air outlet is located on the side of the furnace body near the feed inlet; The pyrolysis furnace further includes, in the direction from the feed inlet to the discharge outlet, a preheating and primary pyrolysis zone, a main volatile matter elution zone, a temperature adjustment transition zone, and an oxidation heating zone arranged sequentially. The pyrolysis furnace further includes a first air inlet and a second air inlet. The first air inlet is connected to the temperature control transition zone and is used to introduce carbon dioxide. The second air inlet is connected to the oxidation heating zone and is used to introduce oxygen-enriched gas. The main volatile matter separation zone does not have an air inlet for directly introducing oxygen-enriched gas.

2. The coal oxygen-enriched autothermal pyrolysis system according to claim 1, characterized in that, The second air inlet includes at least a first sub-air inlet and a second sub-air inlet, wherein the first sub-air inlet is located close to the first air inlet, and the second sub-air inlet is located on the side of the first sub-air inlet away from the first air inlet.

3. The coal oxygen-enriched autothermal pyrolysis system according to claim 1, characterized in that, The coal oxygen-enriched autothermal pyrolysis system also includes an oxygen concentration detection component and multiple temperature detection components. The oxygen concentration detection component is located between the main volatile matter analysis zone and the temperature adjustment transition zone. The multiple temperature detection components are respectively located in the preheating and primary pyrolysis zone, the main volatile matter analysis zone, the temperature adjustment transition zone, and the oxidation heating zone.

4. The coal oxygen-enriched autothermal pyrolysis system according to claim 3, characterized in that, The coal oxygen-enriched autothermal pyrolysis system further includes a first regulating valve and a second regulating valve, wherein the first regulating valve is connected to the first air inlet and the second regulating valve is connected to the second air inlet.

5. A coal oxygen-enriched autothermal pyrolysis method based on the coal oxygen-enriched autothermal pyrolysis system according to any one of claims 1-4, characterized in that, Includes the following steps: Raw coal is fed into the furnace body through the feed inlet. The raw coal passes through the preheating and primary pyrolysis zone and the main volatile matter extraction zone in sequence. In the main volatile matter extraction zone, the main volatile matter removal reaction is completed to generate semi-coke and pyrolysis oil and gas. After completing at least part of the volatile matter removal reaction, the raw coal and the semi-coke pass through the temperature adjustment transition zone and the oxidation heating zone in sequence. The pyrolysis oil and gas are discharged through the gas outlet. Carbon dioxide is introduced into the temperature-regulating transition zone through the first air inlet; Oxygen-rich gas is introduced into the oxidation heating zone through the second air inlet, causing the raw coal and / or semi-coke that have completed at least part of the volatile matter removal reaction to undergo an oxidation reaction and release heat. By adjusting the flow rates of oxygen-enriched gas and / or carbon dioxide, the volume fraction of oxygen entering the main volatile analysis zone is made less than or equal to a first threshold.

6. The method for oxygen-enriched autothermal pyrolysis of coal according to claim 5, characterized in that, The step of adjusting the flow rate of oxygen-enriched gas and / or carbon dioxide to ensure that the volume fraction of oxygen entering the main volatile matter elution zone is less than or equal to a first threshold includes: When the volume fraction of oxygen entering the main volatile analysis zone is detected to be greater than the first threshold, the flow rate of oxygen-enriched gas introduced into the second air inlet is reduced, and / or the flow rate of carbon dioxide introduced into the first air inlet is increased, so that the volume fraction of oxygen entering the main volatile analysis zone is less than or equal to the first threshold.

7. The method for oxygen-enriched autothermal pyrolysis of coal according to claim 5, characterized in that, The second air inlet includes at least a first sub-air inlet and a second sub-air inlet. The first sub-air inlet is located close to the first air inlet, and the second sub-air inlet is located on the side of the first sub-air inlet away from the first air inlet. The coal oxygen-enriched autothermal pyrolysis method further includes: When the volume fraction of oxygen entering the main volatile analysis zone is detected to be greater than the first threshold, the flow rate of oxygen-enriched gas introduced into the first sub-inlet is reduced, or oxygen-enriched gas is introduced into the oxidation heating zone only through the second sub-inlet, so that the volume fraction of oxygen entering the main volatile analysis zone is less than or equal to the first threshold.

8. The method for oxygen-enriched autothermal pyrolysis of coal according to claim 7, characterized in that, The coal oxygen-enriched autothermal pyrolysis method includes at least one of the following: a high effective gas operation mode, a tar protection operation mode, and a high semi-coke yield operation mode, wherein: When the coal oxygen-enriched autothermal pyrolysis system operates in the high effective gas operation mode, the temperature of the oxidation heating zone and the amount of carbon dioxide introduced are increased, so that at least part of the high-temperature semi-coke reacts with carbon dioxide to generate carbon monoxide, which is discharged through the gas outlet. When the coal oxygen-enriched autothermal pyrolysis system is operating in the tar protection mode, the oxygen distribution ratio of the first sub-inlet is reduced, so that oxygen is mainly introduced through the second sub-inlet. When the coal oxygen-enriched autothermal pyrolysis system operates in the high semi-coke yield mode, the amount of oxygen-enriched gas and / or carbon dioxide introduced is reduced to decrease the degree of further oxidation and gasification of the semi-coke, while maintaining the stable autothermal operation of the coal oxygen-enriched autothermal pyrolysis system.

9. The method for oxygen-enriched autothermal pyrolysis of coal according to claim 5, characterized in that, The first threshold is greater than or equal to 0.2% and less than or equal to 1.0%.

10. The method for oxygen-enriched autothermal pyrolysis of coal according to claim 5, characterized in that, The oxygen-enriched gas has an oxygen volume fraction of 30% to 100%, and the oxygen injection rate is 0.05 to 0.60 Nm³ per unit dry coal mass. 3 / kg, wherein the carbon dioxide injection rate is 0.02~1.00 Nm³. 3 / kg.

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