Coal dust pyrolysis apparatus and method

Abstract

The present disclosure discloses a pyrolysis device and method for pulverized coal, comprising: a furnace body, wherein a hearth is defined; a gasification section is arranged at the bottom of the hearth, suitable for mixing low-temperature semi-coke and gasification agent, and making the low-temperature semi-coke gasify to form mixed gas formed by mixing high-temperature semi-coke and coal gas, and making the mixed gas form a gas flow along the extension direction of the hearth; an acceleration section is arranged above the gasification section, suitable for increasing the flow rate of the mixed gas; a pyrolysis section is arranged above the acceleration section, suitable for fully mixing the pulverized coal and the mixed gas under the action of a gas-solid flow field to form pyrolysis semi-coke and pyrolysis gas; and a back-mixing section is arranged above the pyrolysis section, wherein the inner diameter of the back-mixing section is designed to be larger than the inner diameter of the pyrolysis section, so that a part of the pyrolysis semi-coke with larger particle size returns to the pyrolysis section to further increase the material concentration in the pyrolysis section and promote the pyrolysis of the pulverized coal.

Description

TECHNICAL FIELD

[0001] The present disclosure relates to the pyrolysis technical field, in particular to a coal powder pyrolysis device and method. BACKGROUND

[0002] The low-rank coal reserves, represented by lignite and low metamorphic bituminous coal, are abundant, reaching 550 billion tons, accounting for more than 55% of the total coal reserves. Due to the late coal-forming age, the volatile matter content in low-rank coal is generally high, reaching 10-40%. According to estimates, the total amount of volatile matter contained in low-rank coal is equivalent to 100 billion tons of oil and gas resources. At present, more than 90% of low-rank coal is directly used for power generation and heating, which not only has low utilization efficiency and causes environmental pollution, but also results in a huge waste of oil and gas resources. In view of the characteristics of energy resources and the current energy structure, the cascade utilization guided by pyrolysis is an important measure to realize the clean, efficient and high-value utilization of low-rank coal and solve the oil and gas safety problem.

[0003] At present, the vertical furnace pyrolysis process using lump coal (particle size of 25-80 mm) as raw material has been successfully industrialized and applied. Among them, the Lurgi three-stage furnace is the most typical pyrolysis process. Based on this process, a variety of vertical furnace processes have been further developed, such as Sanjiang SJ low-temperature dry distillation furnace, Anshan Thermal Energy Institute ZNZL vertical furnace, Shanxi Metallurgy SH vertical furnace, Guofu furnace, Shenmu Hengyuan dry distillation furnace, etc. However, the lump coal pyrolysis process is generally aimed at producing semi-coke, and the coal tar yield is not high, and the quality of the pyrolysis gas is relatively poor. In addition, this kind of pyrolysis process also has the problems of small single furnace scale and difficulty in scaling up, long pyrolysis time, and the need for wastewater treatment. In view of these problems, it is still necessary to improve the energy efficiency and reduce pollution through technical research and development.

[0004] In modern mechanized coal mining processes, the yield of lump coal accounts for only 20-25% of the total coal production, and more exists in the form of 0-25 mm pulverized coal. At present, a variety of pyrolysis technologies covering moving bed, fluidized bed, gas flow bed and rotary kiln have been gradually developed for pulverized coal. Although there are many pulverized coal pyrolysis processes, due to the limitations of poor homogenization pyrolysis effect of wide-screen pulverized coal, uneven flow, inability to run stably for a long period of time, and insufficient comprehensive utilization efficiency of coal, the pulverized coal pyrolysis technology has not yet been successfully commercialized and is still in the stage of technical research and industrial demonstration. SUMMARY

[0005] In order to solve the above technical problems, the present disclosure provides a coal powder pyrolysis device and method, which can effectively solve the problems of poor homogenization pyrolysis effect of wide-screen pulverized coal, uneven flow, and inability to run stably for a long period of time.

[0006] According to the inventive concept of one aspect of the present disclosure, a pyrolysis device for pulverized coal is provided, which includes a furnace body defining a hearth inside the furnace body; a gasification section arranged at the bottom of the hearth and adapted to mix low-temperature semi-coke and a gasification agent and to gasify the low-temperature semi-coke to form mixed gas of high-temperature semi-coke and coal gas, and to form a gas flow of the mixed gas along the extension direction of the hearth; an acceleration section arranged above the gasification section and adapted to increase the flow rate of the mixed gas; a pyrolysis section arranged above the acceleration section and adapted to mix the pulverized coal and the mixed gas under the action of a gas-solid flow field, to rapidly heat the pulverized coal, and to form pyrolysis semi-coke and pyrolysis gas by pyrolysis; and a back-mixing section arranged above the pyrolysis section and having an inner diameter greater than that of the pyrolysis section, so as to return a part of the pyrolysis semi-coke with a relatively large particle size to the pyrolysis section to provide a heat source for the pyrolysis of the pulverized coal.

[0007] According to some embodiments of the present disclosure, the inner diameter of the acceleration section is configured to be smaller than that of the gasification section, so that the mixed gas passing through the acceleration section is accelerated.

[0008] According to some embodiments of the present disclosure, the acceleration section is configured as a flow guide mechanism including an input end and an output end, and is configured to make the flow rate of the mixed gas at the output end of the flow guide mechanism greater than that at the input end of the flow guide mechanism.

[0009] According to some embodiments of the present disclosure, the acceleration section is provided with a feeding port adapted to input the pulverized coal into the hearth.

[0010] According to some embodiments of the present disclosure, the inner diameter of the pyrolysis section is configured to be greater than that of the acceleration section, and a transition section is formed between the pyrolysis section and the acceleration section, and the transition section is provided with a feeding port adapted to input the pulverized coal into the hearth.

[0011] According to some embodiments of the present disclosure, the pyrolysis device further includes a circulation mechanism arranged between the back-mixing section and the gasification section and adapted to separate a part of the pyrolysis gas and the low-temperature semi-coke, so as to return the separated low-temperature semi-coke to the gasification section to be gasified and to provide a heat source for the pyrolysis of the pulverized coal in the next cycle.

[0012] According to some embodiments of the present disclosure, the circulation mechanism includes a separator connected to the output end of the back-mixing section and adapted to separate the pyrolysis gas from at least a part of the low-temperature semi-coke, and a return feeder arranged between the separator and the gasification section and provided with return air inside the return feeder to return the low-temperature semi-coke separated by the separator to the gasification section.

[0013] According to the inventive concept of another aspect of the present disclosure, a coal pyrolysis method comprises: mixing low-temperature semi-coke and a gasification agent, and gasifying the low-temperature semi-coke to form mixed gas of high-temperature semi-coke and coal gas, and forming a gas flow of the mixed gas along the extension direction of a furnace; increasing the flow rate of the gas flow of the mixed gas along the extension direction of the furnace; feeding coal powder, and fully mixing the coal powder and the mixed gas under the action of a gas-solid flow field, and rapidly heating the coal powder to form pyrolysis semi-coke and pyrolysis gas; and separating the pyrolysis gas and a part of the pyrolysis semi-coke to extract the pyrolysis gas and return a part of the pyrolysis semi-coke with a larger particle size to a pyrolysis section to provide a heat source for coal pyrolysis.

[0014] According to some embodiments of the present disclosure, the pyrolysis method further comprises: re-separating the extracted pyrolysis gas and the pyrolysis semi-coke with a smaller particle size to separate a part of the pyrolysis gas and low-temperature semi-coke, and returning the separated low-temperature semi-coke to the gasification section to be gasified to provide a heat source for coal pyrolysis in the next cycle.

[0015] According to some embodiments of the present disclosure, the pyrolysis method further comprises: configuring a return air to transport the low-temperature semi-coke to the gasification section to participate in the reaction in the next cycle.

[0016] According to the coal pyrolysis device and the pyrolysis method according to the embodiments of the present disclosure, the cross-sectional area of the return mixing section is greater than that of the pyrolysis section, so that the flow rate of the mixed gas in the return mixing section is less than that in the pyrolysis section, and the semi-coke particles with a larger particle size are returned to the pyrolysis section again, the concentration of the semi-coke particles in the pyrolysis section is increased, and the gas-solid mixing effect in the furnace is intense and sufficient, so that the coal powder can be rapidly and uniformly heated, the temperature gradient in the particles is avoided, the rapid and uniform pyrolysis of the coal powder is facilitated, the pyrolysis tar yield is improved, and the added value of the coal is increased. BRIEF DESCRIPTION OF DRAWINGS

[0017] Figure 1 is a working principle diagram of a coal pyrolysis device according to an exemplary embodiment of the present disclosure.

[0018] Figure 2 is a working principle diagram of a coal pyrolysis device according to another exemplary embodiment of the present disclosure.

[0019] Figure 3 is a working principle diagram of a coal pyrolysis device according to still another exemplary embodiment of the present disclosure.

[0020] Figure 4 is a step flow schematic diagram of a coal pyrolysis method according to an exemplary embodiment of the present disclosure.

[0021] In the above drawings, the meanings of the reference signs are as follows:

[0022] 1-furnace;

[0023] 11-gasification section;

[0024] 12-accelerating section;

[0025] 121-flow guide mechanism;

[0026] 13-pyrolysis section;

[0027] 14-back mixing section;

[0028] 15-feed inlet;

[0029] 16-transition section;

[0030] 2-circulating mechanism;

[0031] 21-separator;

[0032] 22-back feeder;

[0033] A-gasification agent;

[0034] B-pulverized coal;

[0035] C-back air;

[0036] D-pyrolysis product. DETAILED DESCRIPTION

[0037] In order to make the purpose, technical solutions and advantages of the present disclosure clearer, the present disclosure is further described in detail below in combination with specific embodiments and with reference to the accompanying drawings.

[0038] In the related art, due to the poor effect of wide-screen pulverized coal homogenization pyrolysis, uneven flow, inability to run stably for a long period, insufficient comprehensive utilization efficiency of coal and other limitations, the pulverized coal pyrolysis efficiency is poor and cannot be commercialized. In order to solve this problem, the cross-sectional area of the accelerating section is set to be smaller than that of the gasification section and the pyrolysis section, the mixed gas flow rate of the accelerating section is greater than that of the gasification section and the pyrolysis section, so that the mixed gas generated in the gasification section is all transported to the pyrolysis section, and at the same time, the particles in the pyrolysis section are prevented from returning to the gasification section, thereby realizing the decoupling of the pulverized coal pyrolysis and the semi-coke gasification in the hearth. The high-temperature semi-coke and coal gas formed by the semi-coke gasification are used as heat sources to rapidly heat the pulverized coal for pyrolysis reaction, thereby realizing the purpose of reducing the complexity of the pyrolysis device and providing stable operation of the device. By setting the cross-sectional area of the back mixing section to be greater than that of the pyrolysis section, the mixed gas flow rate of the back mixing section is less than that of the pyrolysis section, so that the semi-coke particles with larger particles return to the pyrolysis section, thereby increasing the concentration of semi-coke particles in the pyrolysis section, and ultimately realizing the purpose of rapidly and uniformly heating the pulverized coal, rapidly and uniformly pyrolyzing the pulverized coal, improving the pyrolysis tar yield, and increasing the added value of coal.

[0039] Figure 1 is a working principle diagram of a pulverized coal pyrolysis device according to an exemplary embodiment of the present disclosure.

[0040] Figure 2 is a working principle diagram of a coal powder pyrolysis device according to another exemplary embodiment of the present disclosure.

[0041] Figure 3 is a working principle diagram of a coal powder pyrolysis device according to another exemplary embodiment of the present disclosure.

[0042] According to the inventive concept of one aspect of the present disclosure, as Figures 1-3 As shown, a coal powder pyrolysis device is provided, which comprises a furnace body, a gasification section 11, an acceleration section 12, a pyrolysis section 13 and a back-mixing section 14. A hearth 1 is defined in the furnace body. The gasification section 11 is arranged at the bottom of the hearth 1 and is adapted to accommodate the mixture of low-temperature semi-coke and gasification agent A and make the low-temperature semi-coke gasify to form mixed gas of high-temperature semi-coke and coal gas, and make the mixed gas form a gas flow along the extension direction of the hearth 1. The acceleration section 12 is arranged above the gasification section 11 and is adapted to increase the flow rate of the mixed gas. The pyrolysis section 13 is arranged above the acceleration section 12 and is adapted to make the coal powder B and the mixed gas fully mix under the action of the gas-solid flow field, so that the coal powder is rapidly heated to form pyrolysis semi-coke and pyrolysis gas. The back-mixing section 14 is arranged above the pyrolysis section 13, and the inner diameter of the back-mixing section 14 is designed to be larger than that of the pyrolysis section 13, so that a part of the pyrolysis semi-coke with larger particle size returns to the pyrolysis section 13 to provide heat source for the pyrolysis of the coal powder.

[0043] In the present embodiment, the coal powder pyrolysis device and the pyrolysis method achieve that the cross-sectional area of the back-mixing section 14 is larger than that of the pyrolysis section 13, so that the flow rate of the mixed gas in the back-mixing section 14 is smaller than that in the pyrolysis section 13, and the semi-coke particles with larger particle size return to the pyrolysis section 13, thereby increasing the concentration of the semi-coke particles in the pyrolysis section 13, which helps to create a strong and sufficient gas-solid mixing effect in the furnace, so that the coal powder can be rapidly and uniformly heated, the temperature gradient in the particles can be avoided, the rapid and uniform pyrolysis of the coal powder can be facilitated, the pyrolysis tar yield can be improved, and the added value of the coal can be increased.

[0044] According to some embodiments of the present disclosure, the hearth 1 is sequentially provided with the gasification section 11, the acceleration section 12, the pyrolysis section 13 and the back-mixing section 14 from bottom to top. The bottom of the gasification section 11 is provided with a gasification agent A port for introducing the gasification agent A. The gasification agent A reacts with the low-temperature semi-coke to form mixed gas of high-temperature semi-coke and coal gas. The mixed gas is conveyed upward to the pyrolysis section 13 for pyrolyzing the coal powder.

[0045] According to some embodiments of the present disclosure, under the action of the gas flow, the pyrolysis semi-coke is further conveyed upward to the back-mixing section 14. Due to the reduced flow rate, the semi-coke particles with larger particle size are back-mixed, thereby increasing the concentration of the semi-coke particles in the pyrolysis section 13. Part of the fine particles are carried out of the back-mixing section 14 by the gas flow.

[0046] According to some optional embodiments of the present disclosure, the temperature of the gasification section 11 is 850-1100°C, and the superficial wind speed is 0.5-3.0 m / s.

[0047] According to some optional embodiments of the present disclosure, the superficial wind speed of the acceleration section 12 is 5-20 m / s.

[0048] According to some optional embodiments of the present disclosure, the temperature of the pyrolysis section 13 is 550-850°C, and the superficial wind speed is 1.0-3.0 m / s.

[0049] According to some optional embodiments of the present disclosure, the ratio of the inner diameter of the back-mixing section 14 to the pyrolysis section 13 is 1-5, and the superficial wind speed of the back-mixing section 14 is 0.5-2.0 m / s.

[0050] According to some optional embodiments of the present disclosure, the gasification agent A is an oxygen-containing gas, and one or a combination of air, oxygen-enriched gas, oxygen, and steam is used.

[0051] According to some embodiments of the present disclosure, the excess oxygen coefficient of the oxygen-containing gas relative to the coal powder B in the gasification process is 0.05-0.3.

[0052] According to some embodiments of the present disclosure, as shown in FIG. 1, the inner diameter of the acceleration section 12 is configured to be smaller than that of the gasification section 11, so that the mixed gas passing through the acceleration section 12 is accelerated. Figures 1-2

[0053] In the present embodiment, by configuring the cross-sectional area of the acceleration section 12 to be smaller than that of the gasification section 11 and the pyrolysis section 13, the flow rate of the mixed gas in the acceleration section 12 is greater than that in the gasification section 11 and the pyrolysis section 13, so that the mixed gas generated in the gasification section 11 is all transported to the pyrolysis section 13, while avoiding the particles in the pyrolysis section 13 from back-mixing to the gasification section 11, thereby realizing the decoupling of the coal powder pyrolysis and the semi-coke gasification in the hearth 1. The high-temperature semi-coke and the coal gas formed by the gasification are used as heat sources to rapidly heat the coal powder to cause the pyrolysis reaction, thereby reducing the complexity of the pyrolysis device and providing stability for the operation of the device. The structure of the acceleration section 12 can improve the uniformity of the distribution of the mixed gas in the pyrolysis section 13, avoid local fluidization dead zones in the pyrolysis section 13, enhance the physical mixing effect between the coal powder B and the mixed gas, and improve the effectiveness of the coal powder pyrolysis.

[0054] According to some embodiments of the present disclosure, the mixed gas formed by the high-temperature semi-coke and the coal gas is accelerated by the acceleration section 12 and then transported to the pyrolysis section 13, while avoiding the back-mixing of the materials in the pyrolysis section 13 to the gasification section 11.

[0055] According to some embodiments of the present disclosure, the ratio of the inner diameter of the gasification section 11 to the acceleration section 12 is 1.5-4.

[0056] According to some optional embodiments of the present disclosure, the superficial wind speed of the acceleration section 12 is 5-20 m / s.​

[0057] According to some embodiments of the present disclosure, as shown in Figure 3 The acceleration section 12 is configured as a flow guide mechanism 121, including an input end and an output end, and is configured to make the flow rate of the mixed gas at the output end of the flow guide mechanism 121 greater than that at the input end of the flow guide mechanism 121.

[0058] In this embodiment, the flow guide mechanism 121 is configured without the need for a variable-diameter structure, which improves the air distribution uniformity of the mixed gas in the pyrolysis section 13, avoids local fluidization dead zones in the pyrolysis section 13, enhances the physical mixing effect between the pulverized coal B and the mixed gas, and improves the effectiveness of the pyrolysis of the pulverized coal.

[0059] According to some embodiments of the present disclosure, the mixed gas formed by the high-temperature semi-coke and the coal gas is accelerated by the acceleration section 12 and then transported to the pyrolysis section 13, while avoiding backmixing of the materials in the pyrolysis section 13 to the gasification section 11.

[0060] According to some optional embodiments of the present disclosure, the acceleration section 12 is configured with at least three material passages, each of which is uniformly distributed on the cross section of the acceleration section 12.

[0061] According to some optional embodiments of the present disclosure, the superficial wind speed in each passage is still between 5-20 m / s.

[0062] According to some embodiments of the present disclosure, the acceleration section 12 is configured with a feed inlet 15 suitable for inputting the pulverized coal B into the hearth 1.

[0063] According to some optional embodiments of the present disclosure, the feed inlet 15 is arranged at one end of the acceleration section 12 close to the pyrolysis section 13 and is perpendicular to the vertical direction.

[0064] According to some optional embodiments of the present disclosure, the number of feed inlets 15 is not less than 2, and they are uniformly arranged along the cross section of the hearth 1.

[0065] According to some embodiments of the present disclosure, as shown in Figure 2 The inner diameter of the pyrolysis section 13 is configured to be greater than that of the acceleration section 12, and a transition section 16 is formed between the pyrolysis section 13 and the acceleration section 12, and the feed inlet 15 suitable for inputting the pulverized coal B into the hearth 1 is arranged on the transition section 16.

[0066] According to some embodiments of the present disclosure, the feed inlet 15 is arranged on the transition section 16 and has an included angle a with the vertical direction of 45-90°.

[0067] According to some embodiments of the present disclosure, the feed inlet 15 has a certain included angle with the vertical direction, the pulverized coal B contacts the accelerated mixed gas through the feed inlet 15, the gas-solid flow field of the mixed gas is destroyed, the flow field disturbance near the feed inlet 15 is increased, the pulverized coal can better contact the mixed gas, the pulverized coal is uniformly heated, and the pyrolysis efficiency is improved.

[0068] According to some embodiments of the present disclosure, the ratio of the inner diameter of the pyrolysis section 13 to the inner diameter of the acceleration section 12 is 1.5-4.

[0069] According to some embodiments of the present disclosure, the particle size of the pulverized coal B is 0-0.5 mm.

[0070] According to some embodiments of the present disclosure, as shown in Figure 1 The circulating mechanism 2 is arranged between the back-mixing section 14 and the gasification section 11, and is suitable for separating a part of the pyrolysis gas and the low-temperature semi-coke, so that the separated low-temperature semi-coke returns to the gasification section 11 to be gasified, thereby providing a heat source for the pulverized coal pyrolysis in the next cycle.

[0071] In the present embodiment, the circulating mechanism 2 separates the pyrolysis semi-coke with a relatively large particle size and transports it to the next cycle to react with the gasification agent A, thereby realizing a self-heating process, providing heat for the whole cycle, and realizing decoupling of the pulverized coal pyrolysis and the semi-coke gasification in the same reactor. The high-temperature semi-coke and the coal gas generated by the semi-coke gasification are used as the heat source for the rapid pyrolysis of the pulverized coal, which can ensure efficient pyrolysis of the pulverized coal, reduce the number of reaction units, reduce the operation difficulty of the device, and improve the stability of long-period operation of the system.

[0072] According to some embodiments of the present disclosure, the circulating mechanism 2 comprises a separator 21 and a return feeder 22. The separator 21 is connected to the output end of the back-mixing section 14 and is suitable for separating the pyrolysis gas from at least a part of the low-temperature semi-coke; and the return feeder 22 is arranged between the separator 21 and the gasification section 11, and the return feeder 22 is configured with a return air C to return the separated low-temperature semi-coke to the gasification section 11.

[0073] According to some embodiments of the present disclosure, the separator 21 separates the pyrolysis semi-coke with a relatively large particle size from the pyrolysis gas and enters the return feeder 22.

[0074] According to some embodiments of the present disclosure, the bottom of the return feeder 22 is provided with an air inlet for introducing the return air C. The return air C transports the separated pyrolysis semi-coke with a relatively large particle size to the gasification section 11 to react with the gasification agent A, thereby generating high-temperature semi-coke and coal gas.

[0075] According to some optional embodiments of the present disclosure, the return air C is an oxygen-containing gas, which is one or a combination of air, oxygen-enriched gas, oxygen, and steam.

[0076] Figure 4 is a step flow schematic diagram of a pulverized coal pyrolysis method according to an exemplary embodiment of the present disclosure.

[0077] According to another aspect of the present disclosure, the inventive concept is as follows Figure 4As shown in FIG. 1, a pulverized coal pyrolysis method includes steps S410-S440.

[0078] According to some embodiments of the present disclosure, step S410 includes mixing the low-temperature semi-coke and the gasification agent A, gasifying the low-temperature semi-coke to form a mixed gas of high-temperature semi-coke and coal gas, and forming a gas flow of the mixed gas along the extension direction of the hearth 1.

[0079] According to some embodiments of the present disclosure, step S420 includes increasing the flow rate of the gas flow of the mixed gas along the extension direction of the hearth 1.

[0080] According to some embodiments of the present disclosure, step S430 includes introducing the pulverized coal B, and mixing the pulverized coal B and the mixed gas under the action of the gas-solid flow field to rapidly heat the pulverized coal to form pyrolysis semi-coke and pyrolysis gas.

[0081] According to some embodiments of the present disclosure, step S440 includes separating the pyrolysis gas and a part of the pyrolysis semi-coke, and returning a part of the pyrolysis semi-coke with a relatively large particle size to the pyrolysis section to provide a heat source for the pyrolysis of the pulverized coal.

[0082] In the present embodiment, the mixed gas of high-temperature semi-coke and high-temperature coal gas is used as a heat carrier, which helps to create a strong and sufficient gas-solid mixing effect in the furnace. With the pulverized coal B as a raw material, the pulverized coal can be rapidly and uniformly heated under the mixing effect, avoiding the temperature gradient in the particles, and facilitating the rapid and uniform pyrolysis of the pulverized coal, improving the pyrolysis tar yield, and increasing the added value of coal.

[0083] According to some embodiments of the present disclosure, as shown in FIG. 2, the pyrolysis method further includes step S450. Figure 4

[0084] According to some embodiments of the present disclosure, step S450 includes re-separating the extracted pyrolysis gas and the pyrolysis semi-coke with a relatively small particle size, and returning the separated low-temperature semi-coke with a relatively large particle size to the gasification section 11 for gasification to provide a heat source for the pyrolysis of the pulverized coal in the next cycle.

[0085] According to some embodiments of the present disclosure, as shown in FIG. 3, the pyrolysis method further includes step S460. Figure 4

[0086] According to some embodiments of the present disclosure, step S460 includes configuring the return air C to transport the low-temperature semi-coke to the gasification section to participate in the reaction in the next cycle.

[0087] The technical solutions of the present disclosure are further explained below in combination with a specific embodiment. It should be noted that the specific embodiment is only for the purpose of facilitating those skilled in the art to better understand the technical solutions of the present disclosure, and should not be regarded as an unreasonable limitation on the protection scope of the present disclosure.​​

[0088] Embodiment one

[0089] The coal powder B with a particle size of 0-0.5 mm is added to the pyrolysis device from the acceleration section 12 or the pyrolysis section 13, and under the action of the intense gas-solid flow field, is uniformly mixed with the high-temperature semicoke and coal gas (i.e. gas-solid heat carrier) that is transported upward, and a rapid pyrolysis reaction occurs in the pyrolysis section 13 to produce pyrolysis semicoke and pyrolysis gas, and the pyrolysis temperature is 550-850℃. Under the action of the upward gas flow, the semicoke particles are further transported upward to the back-mixing section 14, and due to the reduced flow rate, the relatively coarse semicoke particles undergo back-mixing, thereby increasing the semicoke particle concentration in the pyrolysis section 13. Part of the fine particles are carried out of the back-mixing section 14 by the gas flow and enter the cyclone separator 21, and part of the pyrolysis products D (including relatively fine semicoke and gas products) escape from the cyclone separator 21, and the other part (mainly referring to relatively coarse semicoke) is separated and enters the return feeder 22. Under the action of the return air B, this part of semicoke is transported to the gasification section 11 of the furnace 1 and undergoes partial gasification reaction with the gasification agent A to generate high-temperature semicoke and coal gas, and the gasification temperature is 850-1100℃, and the excess oxygen coefficient of the gasification process is between 0.05-0.3 (relative to raw coal). The high-temperature semicoke and coal gas serve as the gas-solid heat carrier of the coal powder pyrolysis process, are accelerated through the acceleration section 12, and are transported to the pyrolysis section 13 to rapidly heat the coal powder and make it undergo pyrolysis reaction, while avoiding back-mixing of the material in the pyrolysis section 13 to the gasification section 12.

[0090] In the above process, the gasification agent A is an oxygen-containing gas, and one or a combination of air, oxygen-enriched gas, oxygen and steam is used; the return air C is an oxygen-containing gas, and one or a combination of air, oxygen-enriched gas, oxygen and steam is used; the superficial velocity of the gasification section 11 is between 0.5-3.0 m / s, the superficial velocity of the acceleration section 12 is between 5-20 m / s, the superficial velocity of the pyrolysis section 13 is between 1.0-3.0 m / s, and the superficial velocity of the back-mixing section 14 is between 0.5-2.0 m / s.

[0091] Compared with the prior art, the pyrolysis device and pyrolysis method for coal powder according to the embodiments of the present disclosure have the following technical effects:

[0092] (1) The high-temperature semicoke and high-temperature coal gas are used as heat carriers, which helps to create an intense and sufficient gas-solid mixing effect in the furnace, and under this mixing effect, the coal powder can be rapidly and uniformly heated to avoid temperature gradient in the particle interior, which is conducive to rapid and uniform pyrolysis of the coal powder, improves the pyrolysis tar yield, and increases the added value of coal.

[0093] (2) Through the partition setting of the reactor structure, the decoupling of the coal powder pyrolysis and the semi-coke gasification can be realized in the same reactor, the high-temperature semi-coke and the coal gas generated by the semi-coke gasification are used as the heat source of the rapid pyrolysis of the coal powder, the efficient pyrolysis of the coal powder can be ensured, the number of reaction units is reduced, the operation difficulty of the device is reduced, and the stability of long-period operation of the system is improved.

[0094] The above specific embodiments further specifically describe the purposes, technical solutions and beneficial effects of the present disclosure, and it should be understood that the above description is only for specific embodiments of the present disclosure and is not intended to limit the present disclosure. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present disclosure shall be included in the protection scope of the present disclosure.

Claims

1. A pyrolysis device for pulverized coal, characterized in that, include: Furnace body, the furnace body defining the furnace chamber; The gasification section is located at the bottom of the furnace and is suitable for containing a mixture of low-temperature semi-coke and gasifying agent, and for gasifying the low-temperature semi-coke to form a mixed gas of high-temperature semi-coke and coal gas, and for forming an airflow of the mixed gas along the extension direction of the furnace. An acceleration section, located above the gasification section, is suitable for increasing the flow rate of the mixed gas; The pyrolysis section, located above the acceleration section, is suitable for fully mixing the pulverized coal and the mixed gas under the action of the gas-solid flow field, and for rapidly heating the pulverized coal to pyrolyze and form pyrolytic semi-coke and pyrolysis gas. as well as A back-mixing section is located above the pyrolysis section. The inner diameter of the back-mixing section is configured to be larger than that of the pyrolysis section, so that a portion of the pyrolysis semi-coke with larger particle size returns to the pyrolysis section to further increase the material concentration in the pyrolysis section and promote the pyrolysis of pulverized coal.

2. The pyrolysis apparatus according to claim 1, characterized in that, The inner diameter of the acceleration section is configured to be smaller than that of the vaporization section so that the mixture passing through the acceleration section is accelerated.

3. The pyrolysis apparatus according to claim 1, characterized in that, The acceleration section is configured as a flow guiding mechanism, including an input end and an output end, and is constructed such that the flow velocity of the mixed gas at the output end of the flow guiding mechanism is greater than that at the input end of the flow guiding mechanism.

4. The pyrolysis apparatus according to claim 1, characterized in that, The acceleration section is equipped with a feed inlet suitable for feeding the pulverized coal into the furnace.

5. The pyrolysis apparatus according to claim 1, characterized in that, The inner diameter of the pyrolysis section is configured to be larger than the inner diameter of the acceleration section, and a transition section is formed between the pyrolysis section and the acceleration section. The transition section is provided with a feed port suitable for feeding the pulverized coal into the furnace.

6. The pyrolysis apparatus according to any one of claims 1 to 5, characterized in that, It also includes a circulation mechanism, which is located between the back-mixing section and the gasification section. The circulation mechanism is suitable for separating a portion of the pyrolysis gas and the low-temperature semi-coke, so that the separated low-temperature semi-coke is returned to the gasification section for gasification, providing a heat source for the next cycle of pulverized coal pyrolysis.

7. The pyrolysis apparatus according to claim 6, characterized in that, The circulation mechanism includes: A separator, connected to the output of the backmixing section, is suitable for separating pyrolysis gas from at least a portion of the low-temperature semi-coke; and A return feeder is installed between the separator and the gasification section. The return feeder is equipped with return air to return the low-temperature semi-coke separated by the separator to the gasification section.

8. A method for pyrolysis of pulverized coal based on the pyrolysis apparatus according to any one of claims 1 to 7, characterized in that, include: Low-temperature semi-coke and gasifying agent are mixed to gasify the low-temperature semi-coke, thereby forming a mixed gas of high-temperature semi-coke and coal gas, and the mixed gas is made to form an airflow along the extension direction of the furnace. Increase the flow velocity of the gas stream formed by the mixed gas along the extension direction of the furnace chamber; Powdered coal is introduced so that the powdered coal and the mixed gas are fully mixed under the action of the gas-solid flow field, so as to pyrolyze and form pyrolytic semi-coke and pyrolytic gas. as well as The pyrolysis gas and a portion of the pyrolysis coke are separated, and a portion of the larger-particle-size pyrolysis coke is returned to the pyrolysis section to provide a heat source for pulverized coal pyrolysis.

9. The pyrolysis method according to claim 8, characterized in that, The pyrolysis method further includes: separating the extracted pyrolysis gas and the pyrolysis coke with smaller particle size again to separate a portion of the pyrolysis gas and the low-temperature coke, and returning the separated low-temperature coke to the gasification section for gasification to provide a heat source for the next cycle of pulverized coal pyrolysis.

10. The pyrolysis method according to claim 8, characterized in that, The pyrolysis method also includes: configuring return air to transport the low-temperature semi-coke to the gasification section to participate in the reaction of the next cycle.

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