Low-order pulverized coal pyrolysis and cracking conversion system and method

Abstract

The invention belongs to the field of coal chemical industry, and discloses a low-order pulverized coal pyrolysis and cracking conversion system and method. The system comprises a drying device, a pyrolysis device, a cooling device, a direct cracking conversion reaction device and a catalyst carbon deposition oxidation combustion regeneration device, the drying device, the pyrolysis device and the cooling device are all vertical multi-layer fluidized beds; an outlet of a dry pulverized coal discharging pipe of the drying device is connected with an inlet of a dry pulverized coal feeding pipe of the pyrolysis device; and the outlet of the high-temperature semi-coke powder discharging pipe of the pyrolysis device is connected with the inlet of the high-temperature semi-coke powder feeding pipe of the cooling device. According to the invention, quality-divided utilization of coal is realized; and the polycyclic substances are carbonized and deposited on the catalyst, so that the problems of difficult phenolic wastewater treatment, high-temperature coal gas heat energy loss, equipment blockage and the like in the existing low-order pulverized coal pyrolysis and raw coke oven gas cooling and condensing processes are solved.

Description

Technical Field

[0001] This invention belongs to the field of coal chemical industry, and more specifically, relates to a system and method for the pyrolysis and cracking conversion of low-rank pulverized coal. Background Technology

[0002] As coal mining continues, high-quality coal is gradually decreasing, while the proportion of low-rank coal is increasing. However, due to its high moisture content, susceptibility to weathering and spontaneous combustion, difficulty in sorting, and unsuitability for long-distance transportation and storage, the comprehensive utilization of low-rank coal is greatly limited. With the widespread adoption of modern coal mining technologies, the yield of lump coal has decreased, while the yield of pulverized coal exceeds 60%. Pulverized coal presents problems such as easy dust generation, flammability, explosiveness, and difficulty in comprehensive utilization. Therefore, coal pyrolysis and graded utilization have become important pathways for the efficient and clean utilization of low-rank pulverized coal.

[0003] Currently, most industrial low-rank coal pyrolysis technologies can only be used with lump coal, while pulverized coal pyrolysis technology is mostly in the experimental and demonstration stage. The main problems are concentrated in the pulverized coal pyrolysis process and the cooling and separation process of high-temperature pyrolysis gas, i.e., raw coal gas.

[0004] For pulverized coal pyrolysis, rotary kiln pyrolysis technology is commonly used. CN105754624A discloses a "low-rank pulverized coal pyrolysis system, i.e., low-rank pulverized coal pyrolysis method," which proposes a pyrolysis reactor with multiple layers of regenerative radiant tubes arranged at different heights. The heat required for pyrolysis is indirectly supplied through the radiant tubes, eliminating the need for a gaseous heat carrier to dilute the pyrolysis gas, resulting in a high concentration of effective components in the pyrolysis gas. However, this method suffers from uneven heat exchange and a complex structure. CN1066459A discloses a "multi-stage rotary kiln gaseous heat carrier internal and external heating low-to-medium temperature rapid pyrolysis process," which conducts coal drying, pyrolysis, and cooling in three separate rotary kilns. This process handles raw coal with a particle size of 3–30 mm and cannot process pulverized coal with smaller particle sizes.

[0005] Currently, there are two main methods for the cooling and separation process of raw coal gas: direct cooling and ammonia-containing water quenching. Direct cooling using heat exchangers leads to severe blockage of the conveying pipeline due to tar condensation and agglomeration during the cooling process. Ammonia-containing water quenching generates large amounts of wastewater with complex composition and diverse pollutants, resulting in high treatment costs and operating expenses. CN109553508B discloses "An apparatus and method for direct steam reforming of coke oven raw coal gas to produce methanol," proposing to convert all hydrocarbons and non-hydrocarbons such as tar, naphthalene, benzene, and methane in raw coal gas into syngas CO and H2 through non-catalytic reforming at 1300–1500℃. CN118183626A discloses "A system and process for direct reforming of high-temperature raw coal gas to produce hydrogen-rich reducing gas," which optimizes the design of the raw coal gas inlet and oxygen inlet on the reformer, obtaining hydrogen-rich reducing gas from raw coal gas through non-catalytic partial oxidation at 1200–1350℃. The above method, which generates CO and H2 from tar and methane in raw coal gas through partial oxidation or steam reforming, can solve the aforementioned problems. However, the reaction temperature is too high, resulting in high energy consumption. Furthermore, it converts valuable substances such as methane and benzene in the raw coal gas into CO and H2, failing to fully achieve the effect of coal quality utilization.

[0006] Therefore, there is an urgent need to propose a system and method for the pyrolysis and cracking conversion of low-rank pulverized coal. Summary of the Invention

[0007] The purpose of this invention is to address the shortcomings of existing technologies by proposing a system and method for the pyrolysis and cracking conversion of low-rank pulverized coal. This invention achieves differentiated utilization of coal; the carbonization and deposition of polycyclic substances on the catalyst avoids problems such as difficulty in treating phenol-containing wastewater, loss of high-temperature gas heat energy, and equipment blockage that exist in existing low-rank pulverized coal pyrolysis and raw coal gas cooling and condensation processes.

[0008] To achieve the above objectives, the present invention provides a low-rank pulverized coal pyrolysis and cracking conversion system, the system comprising a drying device, a pyrolysis device, a cooling device, a direct cracking conversion reaction device, and a catalyst coking oxidation combustion regeneration device; wherein the drying device, pyrolysis device, and cooling device are all vertical multi-layer fluidized beds;

[0009] The drying device is equipped with a shell, a low-rank pulverized coal feed pipe, a high-temperature nitrogen inlet pipe, and a dry pulverized coal outlet pipe; the low-rank pulverized coal feed pipe is connected to the top of the shell of the drying device; the high-temperature nitrogen inlet pipe and the dry pulverized coal outlet pipe are respectively connected to different sides of the bottom of the shell of the drying device.

[0010] The pyrolysis unit includes a shell, a dry coal powder feed pipe, a high-temperature semi-coke powder discharge pipe, an ash powder discharge pipe, an oxygen-containing gas inlet pipe, and a raw coal gas outlet pipe. The dry coal powder feed pipe is connected to the top of the shell of the pyrolysis unit, and the outlet of the dry coal powder discharge pipe of the dry unit is connected to the inlet of the dry coal powder feed pipe of the pyrolysis unit. The high-temperature semi-coke powder discharge pipe is connected to the shell wall corresponding to the second to fifth fluidized bed layers from the bottom of the pyrolysis unit. The ash powder discharge pipe is connected to the shell wall corresponding to the lowest fluidized bed layer of the pyrolysis unit. The oxygen-containing gas inlet pipe is connected to the bottom of the shell of the dry unit. The raw coal gas outlet pipe is used to send the raw coal gas obtained from the pyrolysis unit to the direct cracking conversion reactor.

[0011] The direct cracking conversion reactor is used to realize the cracking conversion of raw coal gas obtained from the pyrolysis unit; the catalyst carbonization oxidation combustion regeneration unit is used to realize the regeneration of the catalyst used for the cracking conversion of raw coal gas and to send the regenerated catalyst back to the direct cracking conversion reactor.

[0012] The cooling device includes a shell, a high-temperature semi-coke powder feed pipe, a nitrogen inlet pipe, a semi-coke powder product outlet pipe, and a high-temperature nitrogen outlet pipe. The high-temperature semi-coke powder feed pipe is connected to the top of the cooling device shell, and the outlet of the high-temperature semi-coke powder outlet pipe of the pyrolysis device is connected to the inlet of the high-temperature semi-coke powder feed pipe of the cooling device. The nitrogen inlet pipe is connected to the bottom of the cooling device shell. The semi-coke powder product outlet pipe is connected to the shell wall corresponding to the lowest fluidized bed of the cooling device. The high-temperature nitrogen outlet pipe is used to send the high-temperature nitrogen obtained from the cooling device to the high-temperature nitrogen inlet pipe.

[0013] According to the present invention, preferably, the shell of the drying device is provided with multiple layers of porous trays evenly distributed from top to bottom; each layer of porous tray is provided with an interlayer drop pipe, the interlayer drop pipe including a cylindrical tube and a tapering funnel connected sequentially from top to bottom;

[0014] The high-temperature nitrogen inlet pipe is connected to the lower shell wall of the bottom porous tower plate of the drying device, and a gas distribution plate is provided in the shell between the high-temperature nitrogen inlet pipe and the bottom porous tower plate of the drying device.

[0015] The drying device also includes an internal cyclone separator, a combustion gas inlet pipe, an external cyclone separator, and a screw feeder. The internal and external cyclone separators are used to discharge moisture-containing nitrogen from the drying device's shell into the system. The combustion gas inlet pipe is connected to the shell wall between the lowest porous tray and the gas distribution plate of the drying device. The screw feeder's discharge port is connected to the inlet of the low-rank pulverized coal feed pipe.

[0016] Preferably, the vertical multilayer fluidized bed of the drying device has 2 to 6 layers, a diameter of 0.5 to 10 m, and a distance of 200 to 1500 mm between adjacent porous trays; the ratio of the cross-sectional area of ​​the cylindrical section of the interlayer feed pipe to the cross-sectional area of ​​the bed is 0.02 to 0.10, the distance from the top of the cylindrical section of the interlayer feed pipe to the porous tray of the same layer is 100 to 1000 mm, and the distance from the bottom of the constricting funnel of the interlayer feed pipe to the porous tray of the next layer is 50 to 500 mm; the porosity of each porous tray is 0.5 to 5.0%; and the porosity of the gas distribution plate is 0.2 to 2.0%.

[0017] In this invention, if the heat carried by the high-temperature nitrogen from the cooling device cannot meet the drying index requirements of low-rank pulverized coal, the combustion gas inlet pipe is opened. The combustion gas inlet pipe is used to introduce a mixture of coal gas and air into the shell of the drying device.

[0018] In this invention, the outer cyclone separator of each device also returns the solids in the gas carried out by the inner cyclone separator back to each device.

[0019] According to the present invention, preferably, the shell of the pyrolysis device is provided with multiple layers of porous trays evenly distributed from top to bottom; each layer of porous tray is provided with an interlayer drop pipe, the interlayer drop pipe including a cylindrical tube and a tapering funnel connected sequentially from top to bottom;

[0020] The oxygen-containing gas inlet pipe is connected to the lower shell wall of the bottom porous tower plate of the pyrolysis device, and a gas distribution plate is provided in the shell between the oxygen-containing gas inlet pipe and the bottom porous tower plate of the pyrolysis device.

[0021] The pyrolysis device is also equipped with an internal cyclone separator and an external cyclone separator; the internal and external cyclone separators are used to discharge the raw coal gas inside the pyrolysis device to the raw coal gas outlet pipe.

[0022] Preferably, the vertical multilayer fluidized bed of the pyrolysis device has 4 to 12 layers, a diameter of 0.5 to 10 m, and a distance of 200 to 1200 mm between adjacent porous trays; the ratio of the cross-sectional area of ​​the cylindrical section of the interlayer feed pipe to the cross-sectional area of ​​the bed is 0.02 to 0.10, the distance from the top of the cylindrical section of the interlayer feed pipe to the porous tray of the same layer is 100 to 800 mm, and the distance from the bottom of the constricting funnel of the interlayer feed pipe to the porous tray of the next layer is 50 to 400 mm; the porosity of each porous tray is 0.5 to 5.0%; and the porosity of the gas distribution plate is 0.2 to 2.0%.

[0023] According to the present invention, preferably, the cooling device has multiple layers of porous trays evenly distributed from top to bottom inside the shell; each porous tray is provided with an interlayer drop pipe, the interlayer drop pipe including a cylindrical tube and a tapering funnel connected sequentially from top to bottom;

[0024] The nitrogen inlet pipe is connected to the lower shell wall of the bottom porous tray of the cooling device, and a gas distribution plate is provided in the shell between the nitrogen inlet pipe and the bottom porous tray of the cooling device.

[0025] The cooling device is also equipped with an internal cyclone separator and an external cyclone separator; the internal and external cyclone separators are used to discharge the high-temperature nitrogen gas inside the cooling device to the high-temperature nitrogen gas outlet pipe.

[0026] Preferably, the vertical multilayer fluidized bed of the cooling device has 2 to 6 layers, a diameter of 0.5 to 10 m, and a distance of 200 to 1300 mm between adjacent porous trays; the ratio of the cross-sectional area of ​​the cylindrical section of the interlayer feed pipe to the cross-sectional area of ​​the bed is 0.02 to 0.10, the distance from the top of the cylindrical section of the interlayer feed pipe to the porous tray of the same layer is 100 to 1100 mm, and the distance from the bottom of the constricting funnel of the interlayer feed pipe to the porous tray of the next layer is 50 to 500 mm; the porosity of each porous tray is 0.5 to 5.0%; and the porosity of the gas distribution plate is 0.2 to 2.0%.

[0027] According to the present invention, preferably, the direct cracking conversion reactor is a vertical multilayer fluidized bed for direct cracking conversion, wherein the vertical multilayer fluidized bed for direct cracking conversion is provided with a shell, a raw coal gas inlet pipe, an oxygen + water vapor inlet pipe, a catalyst feed pipe, a spent catalyst outlet pipe and a cracking conversion gas outlet pipe.

[0028] The shell of the direct cracking conversion vertical multilayer fluidized bed is evenly distributed with multiple porous trays from top to bottom; each porous tray is provided with an interlayer downcomer, which includes a cylindrical tube and a tapering funnel connected sequentially from top to bottom;

[0029] The raw coal gas inlet pipe is connected to the lower shell wall of the bottom porous tray of the direct cracking and conversion vertical multilayer fluidized bed, and a gas distribution plate is provided in the shell between the raw coal gas inlet pipe and the bottom porous tray of the direct cracking and conversion vertical multilayer fluidized bed; the outlet of the raw coal gas outlet pipe of the pyrolysis unit is connected to the inlet of the raw coal gas inlet pipe of the direct cracking and conversion vertical multilayer fluidized bed.

[0030] The oxygen and water vapor inlet pipe is connected to the shell wall between the lowest porous tray and the gas distribution plate of the vertical multilayer fluidized bed for direct cracking conversion reaction.

[0031] The catalyst feed pipe is connected to the top of the shell of the vertical multilayer fluidized bed for direct cracking conversion reaction;

[0032] The catalyst discharge pipe is connected to the bottom of the shell of the vertical multilayer fluidized bed for direct cracking conversion reaction;

[0033] The shell of the direct cracking conversion vertical multilayer fluidized bed is also equipped with an internal cyclone separator, an external cyclone separator, and a cooling heat exchanger. The internal and external cyclone separators are used to discharge the cracked gas from the shell of the direct cracking conversion vertical multilayer fluidized bed to the heat source inlet of the cooling heat exchanger. The heat source outlet of the cooling heat exchanger is connected to the outside of the system through the cracked gas outlet pipe.

[0034] Preferably, the vertical multilayer fluidized bed of the direct cracking conversion reaction has 3 to 10 layers, a diameter of 0.5 to 10 m, and a distance of 200 to 1000 mm between adjacent porous trays; the ratio of the cross-sectional area of ​​the cylindrical section of the interlayer feed pipe to the cross-sectional area of ​​the bed is 0.02 to 0.10, the distance from the top of the cylindrical section of the interlayer feed pipe to the porous tray of the same layer is 100 to 700 mm, and the distance from the bottom of the constricting funnel of the interlayer feed pipe to the porous tray of the next layer is 50 to 350 mm; the porosity of each porous tray is 0.5 to 5.0%; and the porosity of the gas distribution plate is 0.2 to 2.0%.

[0035] In this invention, the cold source of the cooling heat exchanger is not limited and can be water to be heated into steam.

[0036] According to the present invention, preferably, the direct cracking conversion reactor is a direct cracking conversion U-shaped tube fluidized bed, which includes a shell, a raw coal gas inlet pipe, an oxygen + water vapor inlet pipe, a catalyst feed tank, a catalyst feed pipe, a bottom coal gas inlet pipe, a gas-solid separator, a cyclone separator, a cooling heat exchanger, and a cracked conversion gas outlet pipe;

[0037] The shell of the direct cracking conversion reaction U-shaped tubular fluidized bed is provided with a downward section, a U-shaped bend section and an upward section, wherein the U-shaped bend section is the connecting section between the downward section and the upward section;

[0038] The raw coal gas inlet pipe and the oxygen + water vapor inlet pipe are connected together to the upper side wall inlet of the downward section; the outlet of the catalyst feeding tank is connected to the top inlet of the downward section; the catalyst feed pipe is connected to the inlet of the catalyst feeding tank;

[0039] The bottom gas inlet pipe is connected to the U-shaped elbow section;

[0040] The gas-solid separator is located at the outlet of the upward section. The gas-solid separator is connected to a catalyst discharge pipe and a gas outlet pipe. The gas outlet pipe is connected to the inlet of the cyclone separator. The cyclone separator is provided with a gas outlet and a solid outlet. The gas outlet is connected to the outside of the system in sequence through the heat source inlet and outlet of the cooling heat exchanger and the cracked conversion gas outlet pipe.

[0041] Preferably, the diameter of the down section is 100-800mm and the height is 5-30m; the diameter of the up section is 150-1000mm and the height is 4-25m; the horizontal distance between the centerlines of the up section and the down section is 500-3000mm.

[0042] In this invention, the bottom gas inlet pipe is used to introduce gas into the U-shaped bend section, and the gas introduced by the bottom gas inlet pipe solves the problem of catalyst blockage in the U-shaped bend section.

[0043] According to the present invention, preferably, the catalyst carbon deposition oxidation combustion regeneration device includes a catalyst buffer tank, a riser oxidation combustion regeneration unit, and a turbulent fluidized bed oxidation regeneration sub-unit.

[0044] According to the present invention, preferably, the catalyst buffer tank is provided with a feed inlet for the generated catalyst, a nitrogen inlet for gravity flow, a catalyst outlet for the generated catalyst, and a top inlet; the feed inlet for the generated catalyst is connected to the catalyst discharge pipe for the generated catalyst; the nitrogen inlet for gravity flow is located at the bottom of the catalyst buffer tank; when the direct cracking conversion reactor is a direct cracking conversion U-shaped tubular fluidized bed, the top inlet is connected to the solid outlet of the cyclone separator of the direct cracking conversion U-shaped tubular fluidized bed; when the direct cracking conversion reactor is a direct cracking conversion vertical multilayer fluidized bed, the top inlet is connected to the shell wall of the direct cracking conversion vertical multilayer fluidized bed.

[0045] In this invention, when the direct cracking conversion reactor is a vertical multilayer fluidized bed, the top port is connected to the shell wall of the vertical multilayer fluidized bed to achieve gas exchange between the devices.

[0046] According to the present invention, preferably, the riser oxidation combustion regenerator is provided with a vertical tubular shell, and the bottom end of the vertical tubular shell is provided with a catalyst inlet, a primary air inlet and a secondary air inlet; the catalyst inlet of the vertical tubular shell is connected to the catalyst outlet of the catalyst buffer tank.

[0047] According to the present invention, preferably, the turbulent fluidized bed oxidation regeneration sub-device is provided with a shell, an air inlet pipe, a fresh catalyst feed pipe, a regenerated catalyst discharge pipe, a cooling heat exchanger, and a flue gas outlet pipe; the shell of the turbulent fluidized bed oxidation regeneration sub-device is provided with a hollow straight cylinder, a rapid separator, and an internal cyclone separator, the rapid separator and the internal cyclone separator being located at the top of the hollow straight cylinder; the top end of the vertical tubular shell of the riser oxidation combustion regeneration device passes through the hollow straight cylinder and communicates with the rapid separator, the rapid separator being used to discharge the material in the vertical tubular shell into the hollow straight cylinder; the regenerated catalyst discharge pipe and the fresh catalyst feed pipe are connected to the bottom of the cylinder wall of the hollow straight cylinder, and the... The regenerated catalyst discharge pipe is located below the fresh catalyst feed pipe, and the air inlet pipe is connected to the wall of the hollow straight cylinder located between the regenerated catalyst discharge pipe and the fresh catalyst feed pipe; the outlet of the regenerated catalyst discharge pipe of the turbulent fluidized bed oxidation regeneration sub-unit is connected to the inlet of the catalyst feed pipe of the direct cracking conversion reactor; the internal cyclone separator inside the shell is used to send the flue gas in the hollow straight cylinder to the heat source inlet of the cooling heat exchanger, and the heat source outlet of the cooling heat exchanger is connected to the outside of the system through the flue gas outlet pipe; preferably, the diameter of the vertical tubular shell is 200-800 mm and the height is 5-30 m; the diameter of the hollow straight cylinder is 800-5000 mm and the height is 2-8 m.

[0048] In this invention, "the regenerated catalyst discharge pipe and the fresh catalyst feed pipe are connected to the bottom of the hollow straight cylinder wall, and the regenerated catalyst discharge pipe is located below the fresh catalyst feed pipe." Therefore, when the amount of regenerated catalyst is insufficient, the fresh catalyst and the insufficient amount of regenerated catalyst can be fed together into the direct cracking conversion reactor through the outlet of the regenerated catalyst discharge pipe of the turbulent fluidized bed oxidation regeneration sub-device.

[0049] Another aspect of the present invention provides a method for the pyrolysis and cracking conversion of low-rank pulverized coal, the method employing the above-described system and comprising the following steps:

[0050] S1: Low-rank pulverized coal is fed into the uppermost fluidized bed of the drying device through the low-rank pulverized coal feed pipe, and high-temperature nitrogen from the cooling device is fed into the lowermost fluidized bed of the drying device, so that the low-rank pulverized coal and high-temperature nitrogen exchange heat in the fluidized state to obtain dry coal powder and moisture-containing nitrogen.

[0051] The dried coal powder is fed into the uppermost fluidized bed of the pyrolysis device, so that the dried coal powder comes into contact with the high-temperature combustion gas in a fluidized state, thereby allowing the dried coal powder to obtain heat and undergo a pyrolysis reaction. Raw coal gas is generated in the uppermost fluidized bed of the pyrolysis device, and semi-coke powder is generated in the second to fifth fluidized beds from the bottom of the pyrolysis device.

[0052] A portion of the semi-coke powder is fed downwards layer by layer into the pyrolysis unit, where it comes into contact with oxygen-containing gas in a fluidized state and undergoes an oxidation and combustion reaction to generate ash powder and the high-temperature combustion gas. The ash powder is then discharged from the system. The remaining semi-coke powder is fed into the uppermost fluidized bed of the cooling unit, where it exchanges heat with nitrogen gas fed into the cooling unit in a fluidized state to obtain the high-temperature nitrogen gas and the semi-coke powder product. The semi-coke powder product is then discharged from the system.

[0053] S2: The raw coal gas is sent to the direct cracking and conversion reactor, where it undergoes cracking and conversion under the action of oxygen, steam and catalyst to obtain cracked conversion gas and a spent catalyst; the spent catalyst is sent to the catalyst carbonization oxidation combustion regeneration device for treatment to obtain a regenerated catalyst, which is then sent back to the direct cracking and conversion reactor for use.

[0054] According to the present invention, preferably, in step S1:

[0055] Low-rank pulverized coal is fed into the uppermost fluidized bed of the drying device through the low-rank pulverized coal feed pipe using a screw feeder.

[0056] The low-rank pulverized coal has a moisture content of 16-30% and a particle size of 0.01-1.0 mm.

[0057] The height of the fluidized bed formed by the low-rank pulverized coal and the high-temperature nitrogen gas is 300-800 mm; in this invention, the "height of the fluidized bed" refers to the height to which the low-rank pulverized coal is blown up by the high-temperature nitrogen gas.

[0058] The operating temperature of the uppermost fluidized bed in the drying device shall not be lower than 60℃, and the operating temperature of the lowermost fluidized bed in the drying device shall not be lower than 200℃.

[0059] The empty tower operating velocity of high-temperature nitrogen in each fluidized bed is controlled at 0.2–0.6 m / s;

[0060] The average residence time of the low-rank pulverized coal in the drying device is 20–100 min;

[0061] The moisture content of the dried coal powder is 5.0–8.0%.

[0062] High-temperature nitrogen from the cooling unit is sequentially fed into the lowest fluidized bed of the drying unit through a high-temperature nitrogen outlet pipe, a high-temperature nitrogen inlet pipe, and a gas distribution plate.

[0063] The method further includes discharging the moisture-containing nitrogen gas from the system by sequentially passing it through an inner cyclone separator and an outer cyclone separator;

[0064] The operating temperature of the uppermost fluidized bed in the pyrolysis unit is 400–500℃;

[0065] The operating temperature of the fluidized beds from the bottom 2nd to 5th from the bottom of the pyrolysis unit is 550–650℃;

[0066] The operating temperature of the lowest fluidized bed in the pyrolysis device is 600–800°C; in this invention, the operating temperature of the fluidized bed in the pyrolysis device is achieved through the oxidation-combustion reaction.

[0067] The empty tower operating gas velocity of the high-temperature combustion gas in each fluidized bed is controlled at 0.2–0.6 m / s;

[0068] The average residence time of the dried coal powder in the pyrolysis device is 30 to 200 minutes;

[0069] The operating temperature of the uppermost fluidized bed inside the cooling device shell shall not be lower than 300℃;

[0070] The operating temperature of the lowest fluidized bed inside the cooling device casing shall not exceed 60℃;

[0071] The empty tower operating velocity of nitrogen in each fluidized bed is controlled at 0.2–0.6 m / s;

[0072] The average residence time of the remaining semi-coke powder in the cooling device is 10 to 100 minutes.

[0073] According to the present invention, preferably, in step S2:

[0074] The catalyst is at least one of molecular sieve, alumina, graphite, magnesium oxide and iron oxide;

[0075] When the direct cracking conversion reactor is a U-shaped fluidized bed direct cracking conversion reactor, the cracking conversion of raw coal gas includes: mixing the raw coal gas, oxygen, steam, and catalyst, and sequentially passing them through a downward section, a U-shaped bend section, and an upward section in a fluidized state, causing the tar components in the raw coal gas to undergo catalytic cracking and conversion reactions, obtaining a gas-solid mixture system, which is then separated by a gas-solid separator to obtain solid-containing cracked conversion gas and the catalyst to be generated; the solid-containing cracked conversion gas is then sent to the cyclone separator for further processing to obtain the desired product. The pyrolysis conversion gas and catalyst powder are described; the pyrolysis conversion gas is cooled and sent outside the system; the raw catalyst and catalyst powder are sent to the catalyst buffer tank; preferably, the operating temperature of the downward section is 400-480℃, the gas velocity in the empty tower of the downward section is 3-15m / s, the operating temperature of the upward section is 450-550℃, the gas velocity in the empty tower of the upward section is 3-10m / s, and the average residence time of raw coal gas in the U-shaped tubular fluidized bed of direct cracking conversion reaction is 3-20s;

[0076] When the direct cracking conversion reactor is a vertical multi-layer fluidized bed reactor, the cracking conversion of raw coal gas includes: feeding a catalyst into the uppermost fluidized bed of the U-shaped tube fluidized bed, and feeding raw coal gas, oxygen, and steam into the lowermost fluidized bed of the U-shaped tube fluidized bed, so that the tar components in the raw coal gas undergo catalytic cracking and conversion reactions in a fluidized state, obtaining the cracked conversion gas and the catalyst to be generated; the cracked conversion gas is then cooled and sent outside the system. The catalyst to be generated is sent to the catalyst buffer tank; preferably, the operating temperature of the uppermost fluidized bed of the direct cracking conversion vertical multilayer fluidized bed is 350-450℃, the operating temperature of the lowermost fluidized bed of the direct cracking conversion vertical multilayer fluidized bed is 450-600℃, the empty tower operating gas velocity of the raw coal gas in each fluidized bed is controlled at 0.2-0.5m / s, and the average residence time of the catalyst in the direct cracking conversion vertical multilayer fluidized bed is 1-10min;

[0077] Inside the catalyst buffer tank, the spent catalyst flows under the action of nitrogen into the vertical tubular shell of the riser oxidation combustion regenerator. Inside the vertical tubular shell, the spent catalyst and catalyst powder react with air entering through the primary air inlet in a fluidized state, undergoing oxidation and combustion reactions of the carbon deposited on the catalyst surface. The resulting reaction system flows upward under the action of air entering through the secondary air inlet into the rapid separator within the turbulent fluidized bed oxidation regenerator, and then through the rapid separator into the hollow cylinder of the turbulent fluidized bed oxidation regenerator. Inside the hollow cylinder, the reaction... The system undergoes an oxidation reaction with air to obtain a regenerated catalyst. The regenerated catalyst and optionally a fresh catalyst are fed into a direct cracking conversion reactor. Preferably, the operating gas velocity of nitrogen in the catalyst buffer tank is 0.1–0.2 m / s; the air velocity in the riser oxidation combustion regenerator is 3–10 m / s, and the operating temperature is 450–600°C; the air velocity in the turbulent fluidized bed oxidation regenerator is 0.2–0.6 m / s, and the operating temperature is 450–600°C; the amount of coke deposited on the regenerated catalyst is less than 0.2% based on the total weight of the regenerated catalyst.

[0078] In this invention, the amount of reaction system entering the rapid separator in the turbulent fluidized bed oxidation regeneration sub-device can be adjusted by regulating the amount of air entering through the secondary air inlet.

[0079] The beneficial effects of the technical solution of this invention are as follows: This invention realizes the graded utilization of coal; polycyclic substances are cracked into monocyclic substances and low-carbon hydrocarbons, with some carbonization and deposition on the catalyst, avoiding the problems of difficult treatment of phenol-containing wastewater, high-temperature gas heat loss, and equipment blockage that exist in the existing low-rank pulverized coal pyrolysis and raw coal gas cooling and condensation processes. Specifically:

[0080] (1) In the low-rank pulverized coal drying and pyrolysis stage of this invention, the gas and low-rank pulverized coal with a particle size of 0.01-1.0 mm in the multi-layer fluidized bed come into contact in a fluidized state, resulting in good contact effect. Therefore, this invention achieves the pyrolysis of low-rank coal micropowder with a small particle size. The average residence time of solid low-rank pulverized coal in the bed can be adjusted by adjusting the feed rate, so the multi-layer fluidized bed operation of each device in this invention has great flexibility.

[0081] (2) Existing technology uses the gas after coal gas combustion as the high-temperature combustion gas of the pyrolysis device, while the present invention uses the gas obtained by burning semi-coke powder after low-rank pulverized coal pyrolysis as the high-temperature combustion gas to provide the heat required for low-rank pulverized coal pyrolysis. Therefore, the actual output of coal gas (non-condensable gas after removing benzene and phenol from cracked conversion gas) obtained by the present invention is more than doubled, which increases the yield of differentiated utilization products.

[0082] (3) The present invention uses nitrogen gas and high-temperature semi-coke powder for cooling and heat exchange, i.e. dry quenching, and the obtained high-temperature nitrogen gas is used to heat and dry low-rank pulverized coal in the drying device. Therefore, the present invention makes maximum use of the heat of high-temperature semi-coke powder, which can greatly save the energy consumption required for drying low-rank pulverized coal.

[0083] (4) Unlike the non-catalytic partial oxidation of raw coal gas, the catalytic cracking and conversion of raw coal gas proposed in this invention adopts a method with a lower temperature (400-600℃) and a catalyst, so that the tar components in the raw coal gas undergo catalytic cracking and conversion reactions. Long-chain substances are cracked into short-chain substances, the branches on the cyclic substances break to generate small molecules, some polycyclic substances are cracked into smaller molecules, and the remaining polycyclic substances undergo carbonization reactions and are deposited on the catalyst surface in the form of carbon deposits, while retaining high-value-added small molecules such as benzene and methane, so that the graded utilization of coal is fully reflected.

[0084] (5) The present invention converts the macromolecular substances in the raw coal gas into small molecules and converts them into carbon deposits on the catalyst, which greatly reduces the tar precipitation rate of the converted raw coal gas during the cooling process, avoids the problem of tar condensation clogging pipes and equipment during the cooling process, and also avoids the problem of difficult treatment of phenol-containing wastewater caused by ammonia water cooling shock.

[0085] (6) The U-shaped tubular fluidized bed (raw coal gas direct cracking and conversion reaction device) of the present invention has less back mixing in the downward section and more uniform cracking and conversion. The average residence time in the upward section is extended, which is conducive to the further conversion and carbonization of polycyclic substances and is more compatible with the cracking and conversion reaction of tar components in raw coal gas.

[0086] Other features and advantages of the present invention will be described in detail in the following detailed description section. Attached Figure Description

[0087] The above and other objects, features and advantages of the present invention will become more apparent from the more detailed description of exemplary embodiments of the invention in conjunction with the accompanying drawings, wherein the same reference numerals generally represent the same components in the exemplary embodiments of the invention.

[0088] Figure 1 A schematic diagram of a low-rank pulverized coal pyrolysis and cracking conversion system provided in Embodiment 1 of the present invention is shown.

[0089] Figure 2 A schematic diagram of a low-rank pulverized coal pyrolysis and cracking conversion system provided in Embodiment 4 of the present invention is shown.

[0090] Figure 3 The diagram shows a schematic of the structure of a multi-layer fluidized bed interlayer feed pipe in a low-rank pulverized coal pyrolysis and cracking conversion system provided by the present invention (d represents the diameter of the cylindrical tube of the multi-layer fluidized bed interlayer feed pipe, and d / 2 represents that the bottom diameter of the interlayer feed pipe is 1 / 2 of d).

[0091] The annotations in the attached figures are explained as follows:

[0092] Drying device (1), pyrolysis device (2), cooling device (3), direct cracking conversion U-tube fluidized bed (4), catalyst buffer tank (5), riser oxidation combustion regenerator (6), turbulent fluidized bed oxidation regenerator (7), direct cracking conversion vertical multilayer fluidized bed (8);

[0093] In the drying device (1):

[0094] The drying unit includes a shell (100), a low-rank pulverized coal feed pipe (101), a perforated tray (102), an interlayer feed pipe (103), a combustion gas inlet pipe (104), a high-temperature nitrogen inlet pipe (105), a gas distribution plate (106), a pulverized coal discharge pipe (107), an internal cyclone separator (108), an external cyclone separator (109), and a screw feeder (110).

[0095] In the pyrolysis apparatus (2):

[0096] The shell of the pyrolysis unit (200), the porous tower plate of the pyrolysis unit (201), the dry coal powder feed pipe (202), the interlayer feed pipe of the pyrolysis unit (203), the high temperature semi-coke powder discharge pipe (204), the gas distribution plate of the pyrolysis unit (205), the oxygen-containing gas inlet pipe of the pyrolysis unit (206), the ash powder discharge pipe (207), the internal cyclone separator of the pyrolysis unit (208), the external cyclone separator of the pyrolysis unit (209), and the raw coal gas outlet pipe (210).

[0097] In the cooling device (3):

[0098] The cooling device includes a shell (300), a high-temperature semi-coke powder feed pipe (301), an inter-layer feed pipe (302), a semi-coke powder product discharge pipe (303), a nitrogen inlet pipe (304), a gas distribution plate (305), a porous tray (306), an internal cyclone separator (307), an external cyclone separator (308), and a high-temperature nitrogen outlet pipe (309).

[0099] In the direct cracking conversion reaction U-tube fluidized bed (4):

[0100] The direct cracking conversion U-shaped tubular fluidized bed consists of the shell (400), descending section (401), U-shaped bend section (402), ascending section (403), catalyst feed tank (404), oxygen + steam inlet pipe (405), raw coal gas inlet pipe (406), bottom coal gas inlet pipe (407), and gas-solid separation system. The following components are included: a catalyst feed pipe (408) for a direct cracking and conversion U-shaped tubular fluidized bed, a gas outlet pipe (410) for a direct cracking and conversion U-shaped tubular fluidized bed, a cyclone separator (411) for a direct cracking and conversion U-shaped tubular fluidized bed, a catalyst feed pipe (412) for a direct cracking and conversion U-shaped tubular fluidized bed, a cooling heat exchanger (414) for a direct cracking and conversion U-shaped tubular fluidized bed, and a cracked gas outlet pipe (415) for a direct cracking and conversion U-shaped tubular fluidized bed.

[0101] In catalyst buffer tank (5):

[0102] Shell (500), catalyst feed inlet (501), nitrogen inlet for self-fluidization (502), catalyst outlet (503), top port (504).

[0103] In the riser oxidation combustion regenerator (6):

[0104] Vertical tubular shell (600), catalyst inlet (601), primary air inlet (602), secondary air inlet (603).

[0105] In the turbulent fluidized bed oxidation regeneration sub-unit (7):

[0106] Hollow straight cylinder (700), fast separator (701), internal cyclone separator (702), air inlet pipe (703), fresh catalyst feed pipe (704), regenerated catalyst discharge pipe (705), cooling heat exchanger (706) of turbulent fluidized bed oxidation regeneration sub-device.

[0107] In the direct cracking conversion reaction vertical multilayer fluidized bed (8):

[0108] The shell (800) of the vertical multilayer fluidized bed for direct cracking conversion reaction, the catalyst feed pipe (801) of the vertical multilayer fluidized bed for direct cracking conversion reaction, the interlayer feed pipe (802) of the vertical multilayer fluidized bed for direct cracking conversion reaction, the porous tray (803) of the vertical multilayer fluidized bed for direct cracking conversion reaction, the unused catalyst discharge pipe (804) of the vertical multilayer fluidized bed for direct cracking conversion reaction, the gas distribution plate (805) of the vertical multilayer fluidized bed for direct cracking conversion reaction, and the direct cracking conversion... The raw coal gas inlet pipe (806) of the vertical multi-layer fluidized bed for direct cracking and conversion reaction, the oxygen + steam inlet pipe (807) of the vertical multi-layer fluidized bed for direct cracking and conversion reaction, the internal cyclone separator (808) of the vertical multi-layer fluidized bed for direct cracking and conversion reaction, the external cyclone separator (809) of the vertical multi-layer fluidized bed for direct cracking and conversion reaction, the cooling heat exchanger (810) of the vertical multi-layer fluidized bed for direct cracking and conversion reaction, and the pyrolysis conversion gas outlet pipe (811) of the vertical multi-layer fluidized bed for direct cracking and conversion reaction.

[0109] A. Low-rank pulverized coal, B. Moisture-containing nitrogen, C. Dry pulverized coal, D. Semi-coke powder, E. Ash powder, F. Oxygen-containing gas, G. Semi-coke powder product, H. Nitrogen, I. Bottom coal gas, J. Catalyst awaiting regeneration, K. Regenerated catalyst. Detailed Implementation

[0110] Preferred embodiments of the invention will now be described in more detail. While preferred embodiments of the invention are described below, it should be understood that the invention can be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided so that the invention will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art.

[0111] Example 1

[0112] This embodiment provides a low-rank pulverized coal pyrolysis and cracking conversion system, such as Figure 1 As shown, the system includes a drying device (1), a pyrolysis device (2), a cooling device (3), a direct cracking conversion reaction device, and a catalyst carbon deposition oxidation combustion regeneration device; the drying device (1), the pyrolysis device (2), and the cooling device (3) are all vertical multilayer fluidized beds;

[0113] The drying device (1) is provided with a shell (100), a low-rank pulverized coal feed pipe (101), a high-temperature nitrogen inlet pipe (105), and a dry pulverized coal outlet pipe (107); the low-rank pulverized coal feed pipe (101) is connected to the top of the shell of the drying device (1); the dry pulverized coal outlet pipe (107) is connected to the bottom of the shell of the drying device (1); four layers of porous trays (102) are evenly distributed from top to bottom inside the shell of the drying device (1); each porous tray (102) is provided with an interlayer feed pipe (103), and the layers are connected to the bottom of the shell. The interlayer feed pipe includes a cylindrical tube and a tapering funnel connected sequentially from top to bottom; the vertical multilayer fluidized bed of the drying device (1) has 5 layers with a diameter of 1.5m, and the distance between two adjacent porous trays (102) is 800mm; the ratio of the cross-sectional area of ​​the cylindrical tube of the interlayer feed pipe (103) to the cross-sectional area of ​​the bed is 0.05, the distance from the top of the cylindrical tube of the interlayer feed pipe (103) to the porous tray of the same layer is 800mm, and the distance from the bottom of the tapering funnel of the interlayer feed pipe (103) to the porous tray of the next layer is... The diameter is 400 mm; the porosity of each porous tray (102) is 1.55%; the high-temperature nitrogen inlet pipe is connected to the lower shell wall of the bottom porous tray of the drying device, and a gas distribution plate (106) with an porosity of 0.8% is provided in the shell between the high-temperature nitrogen inlet pipe (105) and the bottom porous tray (102) of the drying device (1); an internal cyclone separator (108) is also provided in the shell of the drying device (1), and the drying device (1) is also provided with a combustion chamber. The gas inlet pipe (104), the outer cyclone separator (109), and the screw feeder (110) are used to discharge the moisture-containing nitrogen gas from the shell of the drying device (1) into the system; the gas inlet pipe (104) is connected to the shell wall between the lowest porous tower plate and the gas distribution plate (106) of the drying device (1); the discharge port of the screw feeder (110) is connected to the inlet of the low-rank pulverized coal feed pipe (101).

[0114] The pyrolysis device is equipped with a shell (200), a dry coal powder feed pipe (202), a high-temperature semi-coke powder discharge pipe (204), an ash powder discharge pipe (207), an oxygen-containing gas inlet pipe (206), and a raw coal gas outlet pipe (210); the dry coal powder feed pipe (202) is connected to the top of the shell of the pyrolysis device (2), and the outlet of the dry coal powder discharge pipe (107) of the drying device (1) is connected to the inlet of the dry coal powder feed pipe (202) of the pyrolysis device (2); the high-temperature semi-coke powder discharge pipe (204) is connected to the bottom of the pyrolysis device from the bottom down. The shell wall corresponding to the third fluidized bed; the ash powder discharge pipe (207) is connected to the shell wall corresponding to the lowest fluidized bed of the pyrolysis unit; the raw coal gas discharge pipe (210) is used to send the raw coal gas obtained from the pyrolysis unit (2) to the direct cracking conversion reactor; the shell of the pyrolysis unit (2) is evenly distributed with 7 layers of porous trays (201) from top to bottom; each porous tray (201) is provided with an interlayer feed pipe (203), the interlayer feed pipe includes a cylindrical tube and a closing funnel connected sequentially from top to bottom; the vertical multilayer fluidized bed of the pyrolysis unit (2) The system has 8 layers, a diameter of 1.8m, and a distance of 1000mm between adjacent porous trays (201). The ratio of the cross-sectional area of ​​the cylindrical section of the interlayer feed pipe (203) to the cross-sectional area of ​​the bed is 0.04. The distance from the top of the cylindrical section of the interlayer feed pipe (203) to the porous tray of the same layer is 600mm, and the distance from the bottom of the funnel of the interlayer feed pipe (203) to the porous tray of the next layer is 300mm. The porosity of each porous tray (201) is 1.8%. The oxygen-containing gas inlet pipe (206) is connected to the pyrolysis device (2). The shell wall below the lowest porous tower plate of the pyrolysis device (2) is provided with a gas distribution plate (205) with an opening rate of 0.67% between the oxygen gas inlet pipe (206) and the lowest porous tower plate of the pyrolysis device (2); the shell of the pyrolysis device (2) is also provided with an internal cyclone separator (208) and an external cyclone separator (209); the internal cyclone separator (208) and the external cyclone separator (209) are used to discharge the raw coal gas in the shell of the pyrolysis device (2) to the raw coal gas outlet pipe (210).

[0115] The direct cracking conversion reactor is used to realize the cracking conversion of raw coal gas obtained from the pyrolysis unit; the direct cracking conversion reactor in this embodiment is a direct cracking conversion U-shaped tube fluidized bed (4), which includes a shell (400), a raw coal gas inlet pipe (406), an oxygen + water vapor inlet pipe (405), a catalyst feed tank (404), a catalyst feed pipe (412), a bottom coal gas inlet pipe (407), a gas-solid separator (408), a cyclone separator (411), a cooling heat exchanger (414), and a cracked conversion gas outlet pipe (415); the shell (400) of the direct cracking conversion U-shaped tube fluidized bed is provided with a downward section (401), a U-shaped elbow section (402), and an upward section (403). The U-shaped bend section (402) is the connecting section between the down section (401) and the up section (403); the raw coal gas inlet pipe (406) and the oxygen + water vapor inlet pipe (405) are connected together to the top side wall inlet of the down section (401); the outlet of the catalyst feeding tank (404) is connected to the top inlet of the down section (401); the catalyst feed pipe (412) is connected to the feed inlet of the catalyst feeding tank (404); the bottom coal gas inlet pipe (407) is connected to the U-shaped bend section (403), and the bottom coal gas inlet pipe (407) is used to introduce coal gas into the U-shaped bend section (403). Under the action of the coal gas introduced by the bottom coal gas inlet pipe (407), the problem of catalyst blockage in the U-shaped bend section (403) is solved. The gas-solid separator (408) is located at the outlet of the upward section (403). The gas-solid separator (408) is connected to the catalyst discharge pipe (409) and the gas outlet pipe (410). The gas outlet pipe (410) is connected to the inlet of the cyclone separator (411). The cyclone separator (411) is provided with a gas outlet and a solid outlet. The gas outlet is connected to the outside of the system in sequence through the heat source inlet and outlet of the cooling heat exchanger (414) and the cracked conversion gas outlet pipe (415). The diameter of the downward section (401) is 300 mm and the height is 20 m. The diameter of the upward section (403) is 400 mm and the height is 20 m. The horizontal distance between the center lines of the upward section (403) and the downward section (401) is 1000 mm.

[0116] The catalyst carbon deposition oxidation combustion regeneration device is used to regenerate the catalyst used in the cracking and conversion of raw coal gas and to send the regenerated catalyst back to the direct cracking and conversion reactor; the catalyst carbon deposition oxidation combustion regeneration device includes a catalyst buffer tank (5), a riser oxidation combustion regenerator (6) and a turbulent fluidized bed oxidation regeneration sub-device (7).

[0117] The catalyst buffer tank (5) is provided with a catalyst feed inlet (501), a nitrogen inlet for self-fluidization (502), a catalyst outlet (503), and a top pipe (504); the catalyst feed inlet (501) is connected to the catalyst discharge pipe (409) of the direct cracking conversion U-shaped tubular fluidized bed; the nitrogen inlet for self-fluidization (502) is located at the bottom of the catalyst buffer tank (5); the top pipe (504) is connected to the solid outlet of the cyclone separator (411) of the direct cracking conversion U-shaped tubular fluidized bed;

[0118] The riser oxidation combustion regenerator is provided with a vertical tubular shell (600). The bottom end of the vertical tubular shell (600) is provided with a catalyst inlet (601), a primary air inlet (602), and a secondary air inlet (603). The catalyst inlet (601) of the vertical tubular shell (600) is connected to the catalyst outlet (503) of the catalyst buffer tank (5). The vertical tubular shell (600) has a diameter of 300 mm and a height of 13 m.

[0119] The turbulent fluidized bed oxidation regeneration sub-device is equipped with a shell, an air inlet pipe (703), a fresh catalyst feed pipe (704), a regenerated catalyst discharge pipe (705), a cooling heat exchanger (706), and a flue gas outlet pipe. Inside the shell of the turbulent fluidized bed oxidation regeneration sub-device are a hollow cylinder (700), a rapid separator (701), and an internal cyclone separator (702). The rapid separator (701) and the internal cyclone separator (702) are located at the top of the hollow cylinder (700). The hollow cylinder (700) has a diameter of 3000 mm and a height of 5 m. The top end of the vertical tubular shell (600) of the riser oxidation combustion regeneration device passes through the hollow cylinder (700) and communicates with the rapid separator (701). The rapid separator (701) is used to discharge the material inside the vertical tubular shell (600) into the hollow cylinder (700). The regenerated catalyst discharge pipe (705) and the fresh catalyst feed pipe (704) are connected to the bottom of the hollow straight cylinder (700), and the regenerated catalyst discharge pipe (705) is located below the fresh catalyst feed pipe (704). The air inlet pipe (703) is connected to the wall of the hollow straight cylinder (700) between the regenerated catalyst discharge pipe (705) and the fresh catalyst feed pipe (704). The outlet of the regenerated catalyst discharge pipe (705) of the turbulent fluidized bed oxidation regeneration sub-device is connected to the inlet of the catalyst feed pipe (412) of the direct cracking conversion reaction U-shaped tube fluidized bed. The internal cyclone separator (702) in the shell is used to send the flue gas in the hollow straight cylinder (700) to the heat source inlet of the cooling heat exchanger (706). The heat source outlet of the cooling heat exchanger (706) is connected to the outside of the system through the flue gas outlet pipe.

[0120] The cooling device (3) is provided with a shell (300), a high-temperature semi-coke powder feed pipe (301), a nitrogen inlet pipe (304), a semi-coke powder product outlet pipe (303), and a high-temperature nitrogen outlet pipe (309); the high-temperature semi-coke powder feed pipe (301) is connected to the top of the shell of the cooling device (3), and the outlet of the high-temperature semi-coke powder outlet pipe of the pyrolysis device (2) is connected to the inlet of the high-temperature semi-coke powder feed pipe (301) of the cooling device (3); the semi-coke powder product outlet pipe (303) is connected to the shell wall corresponding to the lowest fluidized bed of the cooling device (3); the high-temperature nitrogen outlet pipe (309) is used to send the high-temperature nitrogen obtained by the cooling device (3) to the high-temperature nitrogen inlet pipe (105). The cooling device (3) has three layers of porous trays (306) evenly distributed from top to bottom inside its shell. Each porous tray (306) is provided with an interlayer downcomer (302), which includes a cylindrical tube and a constricting funnel connected sequentially from top to bottom. The vertical multilayer fluidized bed of the cooling device (3) has four layers with a diameter of 1.2m. The distance between two adjacent porous trays (306) is 1000mm. The ratio of the cross-sectional area of ​​the cylindrical tube of the interlayer downcomer (302) to the cross-sectional area of ​​the bed is 0.05. The distance from the top of the cylindrical tube of the interlayer downcomer (302) to the porous tray of the same layer is 700mm, and the distance from the bottom of the constricting funnel of the interlayer downcomer (302) to the porous tray of the next layer is 350mm. m; the porosity of each porous tray (306) is 2.4%; the nitrogen inlet pipe (304) is connected to the lower shell wall of the bottom porous tray of the cooling device (3), and a gas distribution plate (305) with a porosity of 1.0% is provided in the shell between the nitrogen inlet pipe (304) and the bottom porous tray of the cooling device (3); an inner cyclone separator (307) is also provided in the shell of the cooling device (3), and an outer cyclone separator (308) is also provided in the cooling device (3); the inner cyclone separator (307) and the outer cyclone separator (308) are used to discharge the high-temperature nitrogen in the shell of the cooling device (3) to the high-temperature nitrogen outlet pipe (309).

[0121] This embodiment also provides a method for the pyrolysis and cracking conversion of low-rank pulverized coal, using the above-described system, including the following steps:

[0122] (1) Low-rank pulverized coal with a moisture content of 20% and a particle size of 0.01-1.0 mm is fed into the uppermost fluidized bed of the drying device (1) by a screw feeder (110) at a feed rate of 105 kg / min. It undergoes gas-solid heat exchange with high-temperature nitrogen in a fluidized state, forming a bubbling or turbulent fluidized bed with a height approximately equal to that of the interlayer downcomer. The moisture contained in the low-rank pulverized coal evaporates into the gas, and the height of the fluidized bed is 400 mm. The operating temperature of the uppermost fluidized bed is 80 °C. As low-rank pulverized coal is continuously added, some of the dried coal powder enters the next fluidized bed through the interlayer downcomer for further fluidization and drying. Low-rank pulverized coal is fluidized and dried layer by layer from top to bottom until the bottom fluidized bed is reached. The operating temperature of the bottom fluidized bed is 230℃. The average residence time of the low-rank pulverized coal in the drying device (1) is 66 min, and the water content in the low-rank pulverized coal is reduced to 7.0%, resulting in dried coal powder. The dried coal powder then enters the pyrolysis device through the dried coal powder discharge pipe (107) and the dried coal powder feed pipe (202). The temperature from the cooling device (3) is 300℃ and the flow rate is 2230 m³ / s. 3 High-temperature nitrogen gas at a temperature of 80°C enters the lowest fluidized bed of the drying device (1) through the gas distribution plate, forming a gas-solid fluidization with low-rank pulverized coal. Then, it passes through the porous tower plates of each layer upwards, and finally passes through the inner cyclone separator and the outer cyclone separator in sequence (the outer cyclone separator also sends the solids in the gas carried out by the inner cyclone separator back to the drying device (1)). The nitrogen gas containing moisture at a temperature of 80°C is sent to the tail gas treatment system for cooling and dust removal before being discharged into the atmosphere or sent to the nitrogen inlet pipe of the cooling device (3). The empty tower gas velocity of high-temperature nitrogen gas in the multi-layer fluidized bed is 0.35 m / s.

[0123] (2) The dried coal powder from step (1) is fed into the uppermost fluidized bed of the pyrolysis device (2) through the dried coal powder feed pipe. It comes into contact with the high-temperature combustion gas from the lower fluidized bed in a fluidized state, thereby allowing the dried coal powder to gain heat and rise in temperature and undergo partial pyrolysis reaction to generate pyrolysis gas containing tar, H2, CH4, CO, CO2, N2, NH3, etc., i.e., raw coal gas. The operating temperature of the uppermost fluidized bed is 450℃. As the dried coal powder continues to enter the pyrolysis device (2), the coal powder is fluidized and pyrolyzed layer by layer until the third fluidized bed from the bottom, where all the volatiles in the coal powder are pyrolyzed to form semi-coke powder. The operating temperature of the third fluidized bed from the bottom is 630℃, the average residence time of the coal powder from the uppermost fluidized bed to the third fluidized bed from the bottom is 168 min, and the average empty tower gas velocity of each fluidized bed is 0.28 m / s. In the fluidized bed from the bottom third layer (1), a portion of the semi-coke powder enters the second-to-last fluidized bed and the bottommost fluidized bed through the interlayer feed pipe. Simultaneously, high-oxygen gas from the oxygen-containing gas inlet pipe (206) enters the bottommost fluidized bed and the second-to-last fluidized bed through the gas distribution plate and porous tray of the pyrolysis device (2). There, it reacts with the high-temperature semi-coke powder coming down from above in a fluidized state, undergoing an oxidation and combustion reaction to generate the high-temperature combustion gas and ash powder. The temperature of the bottommost fluidized bed in the pyrolysis device (2) is 780°C. The high-temperature combustion gas enters each layer sequentially through the porous tray of the pyrolysis device (2), providing heat to the dried coal powder and causing a pyrolysis reaction. The ash powder is then discharged from the system through the ash powder outlet pipe (207). 2) The remaining semi-coke powder is sequentially fed into the uppermost fluidized bed of the cooling device (3) through the high-temperature semi-coke powder discharge pipe (204) and the high-temperature semi-coke powder feed pipe (301). It contacts the nitrogen gas coming from the porous tray of this layer in a fluidized state. The nitrogen gas gains heat and rises in temperature, producing the high-temperature nitrogen gas, while the semi-coke powder releases heat and cools down. The operating temperature of the uppermost fluidized bed of the cooling device (3) is 400℃. As high-temperature semi-coke powder continuously enters the cooling device (3), it passes through the interlayer downcomer into the next fluidized bed. The semi-coke powder undergoes layer-by-layer fluidization and heat exchange to cool down until it reaches the lowermost fluidized bed of the cooling device (3), and then is discharged as semi-coke powder product through the semi-coke powder product discharge pipe (303). The operating temperature of the lowermost fluidized bed is controlled at 58℃, and the residence time of the remaining semi-coke powder in the cooling device (3) is 55 minutes. The nitrogen gas in the cooling device (3) is heated layer by layer upwards to obtain high-temperature nitrogen gas in the uppermost fluidized bed. It then passes through the inner and outer cyclone separators of the cooling device (3) (to separate from the carried-out semi-coke powder), and then enters the uppermost fluidized bed of the drying device (1) through the gas distribution plate. The average empty tower gas velocity of nitrogen in each fluidized bed of the cooling device is 0.5 m / s.

[0124] (3) The raw coal gas obtained in step (2) is sequentially sent through the inner cyclone separator of the pyrolysis device (2), the outer cyclone separator of the pyrolysis device (to separate from the coal powder carried out), the raw coal gas outlet pipe (210) and the raw coal gas inlet pipe into the downward section (401) of the direct cracking conversion reaction U-shaped tubular fluidized bed (4), and mixed with the regenerated catalyst falling into the downward section (401) from the catalyst feed tank (404) and the O2 and H2O entering the downward section from the oxygen + water vapor inlet pipe (405), so that the raw coal gas, O2, H2O and catalyst come into contact in the gas-solid fluidized bed state, and sequentially pass through the downward section (401), the U-shaped bend section (402) and the upward section (403). The operating temperature of the downlink section (401) is 450℃ and the empty tower gas velocity is 10.1 m / s. The operating temperature of the uplink section (403) is 430℃ and the empty tower gas velocity is 6.7 m / s. The residence time of the raw coal gas in the direct cracking and conversion reaction U-shaped tubular fluidized bed (4) is 5.3 s. The raw coal gas undergoes catalytic cracking and conversion reactions in the direct cracking and conversion reaction U-shaped tubular fluidized bed (4). The long-chain substances in the tar components are cracked into short-chain substances, the branches on the cyclic substances break to generate small molecules, some polycyclic substances undergo ring-opening cracking into smaller molecules, and the remaining polycyclic substances undergo carbonization reactions and are deposited on the catalyst surface in the form of carbon deposits to generate cracked conversion gas. The composition of the pyrolysis gas is 16.39% H2, 7.48% CO, 24.77% CO2, 2.07% N2, 0.46% O2, 0.57% H2S, 0.58% SO2, 29.31% H2O, 0.23% NH3, 13.22% CH4, 0.52% C2H4, 2.48% C6H6 (benzene), and 1.92% C6H6O (phenol). All contents are by volume, and the gas flow rate is 1230 m³ / s. 3 / h. Then, the gas-solid material in the upward section (403) is processed by the gas-solid separator (408) to separate most of the catalyst powder. The catalyst powder enters the catalyst buffer tank (5) through the catalyst discharge pipe. The solid-containing pyrolysis conversion gas comes out from the gas outlet pipe and enters the cyclone separator (411). After further separation of the catalyst powder carried by the solid-containing pyrolysis conversion gas, the pyrolysis conversion gas enters the cooling heat exchanger (414) and then enters the next process. The catalyst powder coming out from the bottom of the cyclone separator (411) also enters the catalyst buffer tank through the top pipe (504). The catalyst is a mixture of molecular sieve, iron oxide and magnesium oxide, with a mass ratio of molecular sieve, iron oxide and magnesium oxide of 0.2:0.5:0.3.

[0125] (4) The catalyst in the catalyst buffer tank (5) is a spent catalyst with a carbon deposition of 2.1%; in the catalyst buffer tank (5): the spent catalyst is in contact with a small amount of nitrogen gas coming in from the self-fluidizing nitrogen inlet (502), the nitrogen gas velocity in the empty tower is 0.15m / s, and it is in a micro-fluidized state to enhance the fluidity of the spent catalyst powder, so that the spent catalyst enters the spent catalyst inlet (601) of the riser oxidation combustion regenerator after coming out from the spent catalyst outlet (503). In the riser oxidation combustion regenerator (6): under the impetus of the air coming in from the primary air inlet (602), the gas and solid are in a fluidized bed state, and the oxidation and combustion reaction of carbon deposits on the catalyst surface occurs to obtain the reaction system; the air coming in from the secondary air inlet (603) is used to regulate the amount of the reaction system entering the rapid separator (701) in the turbulent fluidized bed oxidation regenerator (7) upward. The primary air flow rate is 1300m 3 / h, secondary air flow rate is 200m³ / h 3 The operating temperature of the riser oxidation combustion regenerator (6) is 540℃, and the gas flow rate is 6.0 m / s. In the turbulent fluidized bed oxidation regeneration sub-device (7): the high-speed fluidized reaction system within the vertical tubular shell (600) of the riser oxidation combustion regenerator (6) falls into the hollow cylinder (700) through a rapid separator. Inside the hollow cylinder (700), the reaction system comes into fluidized contact with the air entering through the air inlet pipe (703), undergoing further oxidation. The amount of carbon deposited on the catalyst is reduced to 0.18%, resulting in a regenerated catalyst. The operating temperature of the turbulent fluidized bed oxidation regeneration sub-device (7) is 580℃, and the gas flow rate is 0.31 m / s. The regenerated catalyst is returned to the direct cracking conversion reactor via the regenerated catalyst discharge pipe (705) and the catalyst feed pipe (412). The air burned by the oxidation reaction in the hollow cylinder (700) is called low oxygen content flue gas. It enters the cooling heat exchanger (706) of the turbulent fluidized bed oxidation regeneration sub-device (7) through the internal cyclone separator (702) of the turbulent fluidized bed oxidation regeneration sub-device (7). After heat exchange, cooling and environmental protection treatment, it is discharged from the system.

[0126] Example 2

[0127] This embodiment provides a low-rank pulverized coal pyrolysis and cracking conversion system. The only difference between this system and Embodiment 1 is that:

[0128] The vertical multi-layer fluidized bed of the drying device (1) has 5 layers and a diameter of 1.0 m. The distance between two adjacent porous trays (102) is 1000 mm. The ratio of the cross-sectional area of ​​the cylindrical tube of the interlayer feed pipe (103) to the cross-sectional area of ​​the bed is 0.06. The distance from the top of the cylindrical tube of the interlayer feed pipe (103) to the porous tray of the same layer is 600 mm. The distance from the bottom of the hopper of the interlayer feed pipe (103) to the porous tray of the next layer is 300 mm. The porosity of each porous tray (102) is 2.13%. The porosity of the gas distribution plate (106) of the drying device (1) is 1.1%.

[0129] The pyrolysis device (2) has 6 layers of porous trays (201) evenly distributed from top to bottom inside its shell; the vertical multi-layer fluidized bed of the pyrolysis device (2) has 7 layers with a diameter of 1.3m, and the distance between two adjacent porous trays (201) is 900mm; the ratio of the cross-sectional area of ​​the cylindrical tube of the interlayer feed pipe (203) to the cross-sectional area of ​​the bed is 0.052, the distance from the top of the cylindrical tube of the interlayer feed pipe (203) to the porous tray of the same layer is 550mm, and the distance from the bottom of the condensing funnel of the interlayer feed pipe (203) to the porous tray of the next layer is 270mm; the porosity of each porous tray (201) is 2.2%; the porosity of the gas distribution plate (205) of the pyrolysis device is 0.73%.

[0130] The diameter of the downward section (401) of the direct cracking conversion U-shaped fluidized bed is 250 mm and the height is 18 m; the diameter of the upward section (403) is 350 mm and the height is 16 m; the horizontal distance between the centerlines of the upward section (403) and the downward section (401) is 900 mm.

[0131] The vertical tubular shell (600) of the riser oxidation combustion regenerator has a diameter of 250 mm and a height of 12 m;

[0132] The hollow cylindrical part (700) of the turbulent fluidized bed oxidation regeneration sub-device has a diameter of 2500 mm and a height of 4 m;

[0133] The vertical multilayer fluidized bed of the cooling device (3) has 4 layers with a diameter of 1.0m. The distance between two adjacent porous trays (306) is 900mm. The ratio of the cross-sectional area of ​​the cylindrical tube of the interlayer feed pipe (302) to the cross-sectional area of ​​the bed is 0.056. The distance from the top of the cylindrical tube of the interlayer feed pipe (302) to the porous tray of the same layer is 600mm. The distance from the bottom of the hopper of the interlayer feed pipe (302) to the porous tray of the next layer is 300mm. The porosity of each porous tray (306) is 2.13%. The porosity of the gas distribution plate (305) of the cooling device (3) is 1.2%.

[0134] The only difference between the method in this embodiment and that in Embodiment 1 is:

[0135] In step (1):

[0136] The low-rank pulverized coal has a moisture content of 21% and a particle size of 0.01–1.0 mm.

[0137] Low-rank pulverized coal is fed into the uppermost fluidized bed of the drying device (1) by a screw feeder at a feed rate of 58 kg / min;

[0138] The height of the fluidized bed formed by the low-rank pulverized coal and the high-temperature nitrogen is 600 mm.

[0139] The operating temperature of the uppermost fluidized bed of the drying device (1) is 83°C, and the operating temperature of the lowermost fluidized bed of the drying device (1) is 250°C.

[0140] The average residence time of low-rank pulverized coal in the drying device (1) is 72 min;

[0141] The moisture content of the dried coal powder is 7.8%;

[0142] The temperature from the cooling device (3) is 300℃ and the flow rate is 1480m³. 3 High-temperature nitrogen gas per hour enters the lowest fluidized bed of the drying device (1) through the gas distribution plate of the drying device (1);

[0143] The temperature of the nitrogen gas containing moisture is 78℃;

[0144] The high-temperature nitrogen gas in the drying device (1) has an empty tower gas velocity of 0.41 m / s in the multi-layer fluidized bed.

[0145] In step (2):

[0146] The operating temperature of the uppermost fluidized bed in the pyrolysis unit (2) is 460℃;

[0147] The operating temperature of the third fluidized bed from the bottom is 620℃, the average residence time of pulverized coal from the top fluidized bed to the third fluidized bed from the bottom is 131 min, and the average empty tower gas velocity of each fluidized bed is 0.31 m / s.

[0148] The temperature of the lowest fluidized bed in the pyrolysis unit (2) is 770℃;

[0149] The operating temperature of the uppermost fluidized bed of the cooling device (3) is 380°C;

[0150] The operating temperature of the lowest fluidized bed in the cooling device (3) is controlled at 55°C, and the residence time of the remaining semi-coke powder in the cooling device (3) is 106 min. The average empty tower gas velocity of nitrogen in each fluidized bed of the cooling device (3) is 0.41 m / s.

[0151] In step (3):

[0152] The operating temperature of the down section (401) is 460℃ and the empty tower gas velocity is 8.38m / s. The operating temperature of the up section (403) is 410℃ and the empty tower gas velocity is 4.3m / s. The residence time of the raw coal gas in the direct cracking conversion reaction U-shaped tubular fluidized bed (4) is 5.9s.

[0153] The composition of the pyrolysis gas is 15.87% H2, 7.24% CO, 23.96% CO2, 2.01% N2, 0.45% O2, 31.59% H2O, 0.56% H2S, 0.56% SO2, 0.22% NH3, 12.78% CH4, 0.50% C2H4, 2.40% C6H6 (benzene), and 1.86% C6H6O (phenol). All contents are by volume, and the gas flow rate is 663 m³ / s. 3 / h.

[0154] The catalyst is a mixture of alumina, iron oxide and magnesium oxide, with a mass ratio of alumina, iron oxide and magnesium oxide of 0.1:0.5:0.4.

[0155] In step (4):

[0156] The catalyst in the catalyst buffer tank (5) is a spent catalyst with a carbon deposition of 1.6%; the nitrogen gas velocity in the empty tower of the catalyst buffer tank (5) is 0.13 m / s;

[0157] Inside the riser oxidation combustion regenerator (6): the primary air flow rate is 1060 m³ / h. 3 / h, secondary air flow rate is 200m³ / h 3 The operating temperature of the riser oxidation combustion regenerator (6) is 580℃ and the gas flow rate is 7.0m / s.

[0158] Inside the turbulent fluidized bed oxidation regeneration sub-device (7): the operating temperature of the turbulent fluidized bed oxidation regeneration sub-device (7) is 560℃ and the gas flow rate is 0.28m / s.

[0159] Example 3

[0160] This embodiment provides a low-rank pulverized coal pyrolysis and cracking conversion system. The only difference between this system and Embodiment 1 is that:

[0161] The drying device (1) has three layers of porous trays (102) evenly distributed from top to bottom inside its shell; the vertical multi-layer fluidized bed of the drying device (1) has four layers with a diameter of 1.2m, and the distance between two adjacent porous trays (102) is 1200mm; the ratio of the cross-sectional area of ​​the cylindrical tube of the interlayer feed pipe (103) to the cross-sectional area of ​​the bed is 0.054, the distance from the top of the cylindrical tube of the interlayer feed pipe (103) to the porous tray of the same layer is 800mm, and the distance from the bottom of the hopper of the interlayer feed pipe (103) to the porous tray of the next layer is 400mm; the porosity of each porous tray (102) is 1.93%; the porosity of the gas distribution plate (106) of the drying device (1) is 0.93%.

[0162] The vertical multilayer fluidized bed of the pyrolysis device (2) has 8 layers and a diameter of 1.0 m. The distance between two adjacent porous trays (201) is 800 mm. The ratio of the cross-sectional area of ​​the cylindrical tube of the interlayer feed pipe (203) to the cross-sectional area of ​​the bed is 0.043. The distance from the top of the cylindrical tube of the interlayer feed pipe (203) to the porous tray of the same layer is 500 mm. The distance from the bottom of the condensing funnel of the interlayer feed pipe (203) to the porous tray of the next layer is 250 mm. The porosity of each porous tray (201) is 2.43%. The porosity of the gas distribution plate (205) of the pyrolysis device is 1.2%.

[0163] The diameter of the downward section (401) of the direct cracking conversion U-shaped fluidized bed (4) is 250 mm and the height is 16 m; the diameter of the upward section (403) is 300 mm and the height is 15 m; the horizontal distance between the center lines of the upward section (403) and the downward section (401) is 800 mm.

[0164] The vertical tubular shell (600) of the riser oxidation combustion regenerator has a diameter of 280 mm and a height of 10 m;

[0165] The hollow cylindrical section (700) of the turbulent fluidized bed oxidation regeneration sub-device has a diameter of 2000 mm and a height of 4 m.

[0166] The cooling device (3) has four layers of porous trays (306) evenly distributed from top to bottom inside its shell; the vertical multi-layer fluidized bed of the cooling device (3) has five layers with a diameter of 0.8m, and the distance between two adjacent porous trays (306) is 800mm; the ratio of the cross-sectional area of ​​the cylindrical tube of the interlayer feed pipe (302) to the cross-sectional area of ​​the bed is 0.061, the distance from the top of the cylindrical tube of the interlayer feed pipe (302) to the porous tray of the same layer is 500mm, and the distance from the bottom of the condensing funnel of the interlayer feed pipe (302) to the porous tray of the next layer is 250mm; the porosity of each porous tray (306) is 2.54%; and the porosity of the gas distribution plate (305) of the cooling device (3) is 1.32%.

[0167] The only difference between the method in this embodiment and that in Embodiment 1 is:

[0168] In step (1):

[0169] The low-rank pulverized coal has a moisture content of 23% and a particle size of 0.01–1.0 mm.

[0170] Low-rank pulverized coal is fed into the uppermost fluidized bed of the drying device (1) by a screw feeder (110) at a feed rate of 65 kg / min;

[0171] The height of the fluidized bed formed by the low-rank pulverized coal and the high-temperature nitrogen is 800 mm;

[0172] The operating temperature of the uppermost fluidized bed of the drying device (1) is 76°C, and the operating temperature of the lowermost fluidized bed of the drying device (1) is 260°C.

[0173] The average residence time of low-rank pulverized coal in the drying device (1) is 87 min;

[0174] The water content of the dried coal powder is 6.9%;

[0175] The temperature from the cooling device (3) is 320°C and the flow rate is 1500 m³ / h. 3 High-temperature nitrogen gas per hour enters the lowest fluidized bed of the drying device (1) through the gas distribution plate of the drying device (1);

[0176] The temperature of the nitrogen gas containing moisture is 76℃;

[0177] The high-temperature nitrogen gas in the drying device (1) has an empty tower gas velocity of 0.39 m / s in the multi-layer fluidized bed. In this embodiment, combustion gas (a mixture of coal gas and air) is also introduced into the drying device (1) through the combustion gas inlet pipe (104). The combustion gas temperature is 600°C and the empty tower gas velocity is 0.1 m / s.

[0178] In step (2):

[0179] The operating temperature of the uppermost fluidized bed in the pyrolysis unit (2) is 480℃;

[0180] The operating temperature of the third fluidized bed from the bottom is 640℃, the average residence time of pulverized coal from the top fluidized bed to the third fluidized bed from the bottom is 68 min, and the average empty tower gas velocity of each fluidized bed is 0.34 m / s.

[0181] The temperature of the lowest fluidized bed in the pyrolysis unit (2) is 760℃;

[0182] The operating temperature of the uppermost fluidized bed of the cooling device (3) is 350°C;

[0183] The operating temperature of the lowest fluidized bed in the cooling device (3) is controlled at 53°C, and the residence time of the remaining semi-coke powder in the cooling device (3) is 69 min. The average empty tower gas velocity of nitrogen in each fluidized bed of the cooling device (3) is 0.52 m / s.

[0184] In step (3):

[0185] The operating temperature of the down section (401) is 480℃ and the empty tower gas velocity is 5.44m / s. The operating temperature of the up section (403) is 450℃ and the empty tower gas velocity is 3.8m / s. The residence time of the raw coal gas in the direct cracking conversion reaction U-shaped tubular fluidized bed (4) is 6.9s.

[0186] The composition of the pyrolysis gas is 16.41% H2, 7.52% CO, 24.89% CO2, 2.08% N2, 0.46% O2, 0.58% H2S, 0.58% SO2, 29.02% H2O, 0.23% NH3, 13.28% CH4, 0.52% C2H4, 2.49% C6H6 (benzene), and 1.92% C6H6O (phenol). All contents are by volume, and the gas flow rate is 650 m³ / s. 3 / h.

[0187] The catalyst is a mixture of molecular sieve, graphite, iron oxide and magnesium oxide, with a mass ratio of molecular sieve, graphite, iron oxide and magnesium oxide of 0.28:0.02:0.4:0.3. In this embodiment, the graphite is specifically multi-metal (cesium, copper, molybdenum and vanadium) oxygen cluster intercalated expanded graphite.

[0188] In step (4):

[0189] The catalyst in the catalyst buffer tank (5) is a spent catalyst with a carbon deposition of 1.6%; the nitrogen gas velocity in the empty tower of the catalyst buffer tank (5) is 0.19 m / s;

[0190] Inside the riser oxidation combustion regenerator (6): the primary air flow rate is 1300 m³ / h.3 / h, secondary air flow rate is 180m³ / h 3 The operating temperature of the riser oxidation combustion regenerator (6) is 570℃ and the gas flow rate is 8.0m / s.

[0191] In the turbulent fluidized bed oxidation regeneration sub-unit (7): the amount of carbon deposited on the catalyst is reduced to 0.17%, and a regenerated catalyst is obtained. The operating temperature of the turbulent fluidized bed oxidation regeneration sub-unit (7) is 540℃ and the gas flow rate is 0.41m / s.

[0192] Example 4

[0193] This embodiment provides a low-rank pulverized coal pyrolysis and cracking conversion system. The only difference between this system and Embodiment 1 is that:

[0194] The drying device (1) has 5 layers of porous trays (102) evenly distributed from top to bottom inside its shell; the vertical multi-layer fluidized bed of the drying device (1) has 6 layers with a diameter of 1.0 m, and the distance between two adjacent porous trays (102) is 1000 mm; the ratio of the cross-sectional area of ​​the cylindrical tube of the interlayer feed pipe (103) to the cross-sectional area of ​​the bed is 0.062, the distance from the top of the cylindrical tube of the interlayer feed pipe (103) to the porous tray of the same layer is 700 mm, and the distance from the bottom of the condensing funnel of the interlayer feed pipe (103) to the porous tray of the next layer is 350 mm; the porosity of each porous tray (102) is 2.45%; the porosity of the gas distribution plate (106) of the drying device (1) is 1.23%.

[0195] The pyrolysis device (2) has 9 layers of porous trays (201) evenly distributed from top to bottom inside its shell; the vertical multi-layer fluidized bed of the pyrolysis device (2) has 10 layers with a diameter of 1.0 m, and the distance between two adjacent porous trays (201) is 800 mm; the ratio of the cross-sectional area of ​​the cylindrical tube of the interlayer feed pipe (203) to the cross-sectional area of ​​the bed is 0.061, the distance from the top of the cylindrical tube of the interlayer feed pipe (203) to the porous tray of the same layer is 500 mm, and the distance from the bottom of the condensing funnel of the interlayer feed pipe (203) to the porous tray of the next layer is 250 mm; the porosity of each porous tray (201) is 2.12%; the porosity of the gas distribution plate (205) of the pyrolysis device is 1.03%;

[0196] The direct cracking conversion reactor is used to realize the cracking conversion of raw coal gas obtained from the pyrolysis unit; the direct cracking conversion reactor in this embodiment is a direct cracking conversion vertical multilayer fluidized bed (8), which is provided with a shell (800), a raw coal gas inlet pipe (806), an oxygen + water vapor inlet pipe (807), a catalyst feed pipe (801), a spent catalyst outlet pipe (804), and a cracked conversion gas outlet pipe (801); the shell (800) of the direct cracking conversion vertical multilayer fluidized bed is evenly distributed with 7 layers of porous trays (803) from top to bottom; each porous tray (803) is provided with an interlayer downcomer (802), which includes The vertical multi-layer fluidized bed (8) of the direct cracking conversion reaction consists of a cylindrical tube and a tapering funnel connected sequentially from top to bottom; the vertical multi-layer fluidized bed has 8 layers, a diameter of 0.8 m, and a distance of 1000 mm between adjacent porous trays (803); the ratio of the cross-sectional area of ​​the cylindrical tube of the interlayer feed pipe (802) to the cross-sectional area of ​​the bed is 0.053, the distance from the top of the cylindrical tube of the interlayer feed pipe (802) to the porous tray of the same layer is 600 mm, and the distance from the bottom of the tapering funnel of the interlayer feed pipe to the porous tray of the next layer is 300 mm; the opening ratio of each porous tray is 2.13%; the raw coal gas inlet pipe (806) is connected to the bottommost porous tray of the vertical multi-layer fluidized bed (8) of the direct cracking conversion reaction. The lower shell wall of the direct cracking and conversion vertical multi-layer fluidized bed (8) is provided with a gas distribution plate (805) with an opening ratio of 0.8% between the raw coal gas inlet pipe (806) and the lowest porous tower plate (803) of the direct cracking and conversion vertical multi-layer fluidized bed (8); the outlet of the raw coal gas outlet pipe of the pyrolysis device (2) is connected to the inlet of the raw coal gas inlet pipe of the direct cracking and conversion vertical multi-layer fluidized bed (8); the oxygen + water vapor inlet pipe (807) is connected to the shell wall between the lowest porous tower plate and the gas distribution plate (805) of the direct cracking and conversion vertical multi-layer fluidized bed (8); the catalyst feed pipe (801) is connected to the top of the shell of the direct cracking and conversion vertical multi-layer fluidized bed (8); The catalyst discharge pipe (804) is connected to the bottom of the shell of the direct cracking conversion vertical multilayer fluidized bed (8); the shell of the direct cracking conversion vertical multilayer fluidized bed (8) is also provided with an internal cyclone separator (808), and the direct cracking conversion vertical multilayer fluidized bed (8) is also provided with an external cyclone separator (809) and a cooling heat exchanger (810); the internal cyclone separator (808) and the external cyclone separator (809) are used to discharge the cracked conversion gas in the shell of the direct cracking conversion vertical multilayer fluidized bed (8) to the heat source inlet of the cooling heat exchanger (810), and the heat source outlet of the cooling heat exchanger (810) is connected to the outside of the system through the cracked conversion gas outlet pipe (811);

[0197] The vertical tubular shell (600) of the riser oxidation combustion regenerator has a diameter of 300 mm and a height of 20 m;

[0198] The hollow cylindrical section (700) of the turbulent fluidized bed oxidation regeneration sub-device has a diameter of 2300 mm and a height of 5 m;

[0199] The cooling device (3) has 5 layers of porous trays (306) evenly distributed from top to bottom inside its shell; the vertical multi-layer fluidized bed of the cooling device (3) has 6 layers with a diameter of 0.8m and a distance of 700mm between two adjacent porous trays (306); the ratio of the cross-sectional area of ​​the cylindrical tube of the interlayer feed pipe (302) to the cross-sectional area of ​​the bed is 0.071, the distance from the top of the cylindrical tube of the interlayer feed pipe (302) to the porous tray of the same layer is 400mm, and the distance from the bottom of the condensing funnel of the interlayer feed pipe (302) to the porous tray of the next layer is 200mm; the porosity of each porous tray (306) is 2.28%; and the porosity of the gas distribution plate (305) of the cooling device (3) is 1.02%.

[0200] The method in this embodiment differs from that in Embodiment 1 only in that:

[0201] In step (1):

[0202] The low-rank pulverized coal has a moisture content of 18% and a particle size of 0.01–1.0 mm.

[0203] Low-rank pulverized coal is fed into the uppermost fluidized bed of the drying device (1) at a feed rate of 51 kg / min;

[0204] The height of the fluidized bed formed by the low-rank pulverized coal and the high-temperature nitrogen is 700 mm.

[0205] The operating temperature of the uppermost fluidized bed of the drying device (1) is 81°C, and the operating temperature of the lowermost fluidized bed of the drying device (1) is 270°C.

[0206] The average residence time of low-rank pulverized coal in the drying device (1) is 95 min;

[0207] The water content of the dried coal powder is 5.8%;

[0208] The temperature from the cooling device (3) is 312°C and the flow rate is 960 m³ / h. 3 High-temperature nitrogen gas per hour enters the lowest fluidized bed of the drying device (1) through the gas distribution plate of the drying device (1);

[0209] The temperature of the nitrogen gas containing moisture is 75℃;

[0210] The high-temperature nitrogen gas in the drying device (1) has an empty tower gas velocity of 0.34 m / s in the multi-layer fluidized bed.

[0211] In step (2):

[0212] The operating temperature of the uppermost fluidized bed in the pyrolysis unit (2) is 475°C.

[0213] The operating temperature of the third fluidized bed from the bottom is 623℃, the average residence time of pulverized coal from the top fluidized bed to the third fluidized bed from the bottom is 110 min, and the average empty tower gas velocity of each fluidized bed is 0.38 m / s.

[0214] The temperature of the lowest fluidized bed in the pyrolysis unit (2) is 782℃;

[0215] The operating temperature of the uppermost fluidized bed of the cooling device (3) is 340°C;

[0216] The operating temperature of the lowest fluidized bed in the cooling device (3) is controlled at 50°C, and the residence time of the remaining semi-coke powder in the cooling device (3) is 85 min. The average empty tower gas velocity of nitrogen in each fluidized bed of the cooling device is 0.38 m / s.

[0217] In step (3):

[0218] The raw coal gas obtained in step (2) is sequentially fed into the bottom of the vertical multi-layer fluidized bed (8) for direct cracking and conversion reaction through the inner cyclone separator of the pyrolysis device (2), the outer cyclone separator of the pyrolysis device (2) (separating from the coal powder carried out), the raw coal gas outlet pipe (210), and the raw coal gas inlet pipe; O2 and H2O are also fed into the bottom of the vertical multi-layer fluidized bed (8) for direct cracking and conversion reaction through the oxygen + water vapor inlet pipe (807); then O2, H2O, and raw coal gas enter the lowest fluidized bed after passing through the gas distribution plate (805). Under the action of the catalyst, the tar components in the raw coal gas undergo catalytic cracking and conversion reactions, long-chain substances are cracked into short-chain substances, and the branches on the cyclic substances break to generate small molecules, and some polycyclic substances undergo catalytic cracking and conversion reactions. The material undergoes ring-opening cracking into smaller molecules, and the remaining polycyclic substances undergo carbonization reactions and are deposited on the catalyst surface in the form of carbon deposits. The raw coal gas and the catalyst are fluidized in a multi-layer fluidized bed in a countercurrent manner, and finally the cracked gas is obtained. The cracked gas is processed by the inner cyclone separator (808) and the outer cyclone separator (809) in the uppermost fluidized bed, and then enters the cooling heat exchanger (810) for cooling and heat exchange before entering the next process. The catalyst enters the uppermost fluidized bed of the vertical multi-layer fluidized bed (8) of the direct cracking conversion reaction from the catalyst feed pipe, and is fluidized in each fluidized bed with the raw coal gas through the inter-layer downcomer from top to bottom. The catalyst powder enters the catalyst buffer tank (5) through the spent catalyst outlet pipe in the lowermost fluidized bed. The operating temperature of the lowermost fluidized bed is 580℃, the operating temperature of the uppermost fluidized bed is 445℃, and the average empty tower gas velocity of each fluidized bed is 0.33m / s. The composition of the pyrolysis gas is 17.10% H2, 7.82% CO, 25.85% CO2, 2.16% N2, 0.48% O2, 26.22% H2O, 0.6% H2S, 0.6% SO2, 0.24% NH3, 13.79% CH4, 0.54% C2H4, 2.59% C6H6 (benzene), and 2.01% C6H6O (phenol). All concentrations are by volume, and the gas flow rate is 550 m³ / s. 3 / h. The catalyst is a mixture of alumina, graphite, iron oxide and magnesium oxide, with a mass ratio of alumina, graphite, iron oxide and magnesium oxide of 0.09:0.01:0.3:0.6. In this embodiment, the graphite is specifically N,P co-doped graphene.

[0219] In step (4):

[0220] The catalyst in the catalyst buffer tank (5) is a spent catalyst with a carbon deposition of 1.7%; the nitrogen gas velocity in the empty tower of the catalyst buffer tank (5) is 0.1 m / s;

[0221] Inside the riser oxidation combustion regenerator (6): the primary air flow rate is 1800 m³ / s. 3 / h, secondary air flow rate is 210m³ / h3 The operating temperature of the riser oxidation combustion regenerator (6) is 560℃ and the gas flow rate is 8.5m / s.

[0222] In the turbulent fluidized bed oxidation regeneration sub-unit (7): the amount of carbon deposited on the catalyst is reduced to 0.19%, and a regenerated catalyst is obtained. The operating temperature of the turbulent fluidized bed oxidation regeneration sub-unit (7) is 550°C, and the gas flow rate is 0.35 m / s.

[0223] The various embodiments of the present invention have been described above. These descriptions are exemplary and not exhaustive, nor are they limited to the disclosed embodiments. Many modifications and variations will be apparent to those skilled in the art without departing from the scope and spirit of the described embodiments.

Claims

1. A low-rank pulverized coal pyrolysis and cracking conversion system, characterized in that, The system includes a drying unit, a pyrolysis unit, a cooling unit, a direct cracking conversion reactor, and a catalyst coking oxidation combustion regeneration unit; the drying unit, pyrolysis unit, and cooling unit are all vertical multilayer fluidized beds; The drying device is equipped with a shell, a low-rank pulverized coal feed pipe, a high-temperature nitrogen inlet pipe, and a dry pulverized coal outlet pipe; the low-rank pulverized coal feed pipe is connected to the top of the shell of the drying device; the high-temperature nitrogen inlet pipe and the dry pulverized coal outlet pipe are respectively connected to different sides of the bottom of the shell of the drying device. The pyrolysis unit includes a shell, a dry coal powder feed pipe, a high-temperature semi-coke powder discharge pipe, an ash powder discharge pipe, an oxygen-containing gas inlet pipe, and a raw coal gas outlet pipe. The dry coal powder feed pipe is connected to the top of the shell of the pyrolysis unit, and the outlet of the dry coal powder discharge pipe of the dry unit is connected to the inlet of the dry coal powder feed pipe of the pyrolysis unit. The high-temperature semi-coke powder discharge pipe is connected to the shell wall corresponding to the second to fifth fluidized bed layers from the bottom of the pyrolysis unit. The ash powder discharge pipe is connected to the shell wall corresponding to the lowest fluidized bed layer of the pyrolysis unit. The oxygen-containing gas inlet pipe is connected to the bottom of the shell of the dry unit. The raw coal gas outlet pipe is used to send the raw coal gas obtained from the pyrolysis unit to the direct cracking conversion reactor. The direct cracking conversion reactor is used to realize the cracking conversion of raw coal gas obtained from the pyrolysis unit; the catalyst carbonization oxidation combustion regeneration unit is used to realize the regeneration of the catalyst used for the cracking conversion of raw coal gas and to send the regenerated catalyst back to the direct cracking conversion reactor. The cooling device includes a shell, a high-temperature semi-coke powder feed pipe, a nitrogen inlet pipe, a semi-coke powder product outlet pipe, and a high-temperature nitrogen outlet pipe. The high-temperature semi-coke powder feed pipe is connected to the top of the cooling device shell, and the outlet of the high-temperature semi-coke powder outlet pipe of the pyrolysis device is connected to the inlet of the high-temperature semi-coke powder feed pipe of the cooling device. The nitrogen inlet pipe is connected to the bottom of the cooling device shell. The semi-coke powder product outlet pipe is connected to the shell wall corresponding to the lowest fluidized bed of the cooling device. The high-temperature nitrogen outlet pipe is used to send the high-temperature nitrogen obtained from the cooling device to the high-temperature nitrogen inlet pipe.

2. The low-rank pulverized coal pyrolysis and cracking conversion system according to claim 1, wherein, The drying device has multiple layers of porous trays evenly distributed from top to bottom inside its shell; each layer of porous tray is provided with an interlayer drop pipe, which includes a cylindrical tube and a tapering funnel connected sequentially from top to bottom. The high-temperature nitrogen inlet pipe is connected to the lower shell wall of the bottom porous tower plate of the drying device, and a gas distribution plate is provided in the shell between the high-temperature nitrogen inlet pipe and the bottom porous tower plate of the drying device. The drying device also includes an internal cyclone separator, a combustion gas inlet pipe, an external cyclone separator, and a screw feeder. The internal and external cyclone separators are used to discharge moisture-containing nitrogen from the drying device's shell into the system. The combustion gas inlet pipe is connected to the shell wall between the lowest porous tray and the gas distribution plate of the drying device. The screw feeder's discharge port is connected to the inlet of the low-rank pulverized coal feed pipe. Preferably, the vertical multilayer fluidized bed of the drying device has 2 to 6 layers, a diameter of 0.5 to 10 m, and a distance of 200 to 1500 mm between adjacent porous trays; the ratio of the cross-sectional area of ​​the cylindrical section of the interlayer feed pipe to the cross-sectional area of ​​the bed is 0.02 to 0.10, the distance from the top of the cylindrical section of the interlayer feed pipe to the porous tray of the same layer is 100 to 1000 mm, and the distance from the bottom of the constricting funnel of the interlayer feed pipe to the porous tray of the next layer is 50 to 500 mm; the porosity of each porous tray is 0.5 to 5.0%; and the porosity of the gas distribution plate is 0.2 to 2.0%.

3. The low-rank pulverized coal pyrolysis and cracking conversion system according to claim 1, wherein, The shell of the pyrolysis device is evenly distributed with multiple layers of porous trays from top to bottom; each layer of porous tray is provided with an interlayer drop pipe, which includes a cylindrical tube and a tapering funnel connected sequentially from top to bottom; The oxygen-containing gas inlet pipe is connected to the lower shell wall of the bottom porous tower plate of the pyrolysis device, and a gas distribution plate is provided in the shell between the oxygen-containing gas inlet pipe and the bottom porous tower plate of the pyrolysis device. The pyrolysis device is also equipped with an internal cyclone separator and an external cyclone separator; the internal and external cyclone separators are used to discharge the raw coal gas inside the pyrolysis device to the raw coal gas outlet pipe. Preferably, the vertical multilayer fluidized bed of the pyrolysis device has 4 to 12 layers, a diameter of 0.5 to 10 m, and a distance of 200 to 1200 mm between adjacent porous trays; the ratio of the cross-sectional area of ​​the cylindrical section of the interlayer feed pipe to the cross-sectional area of ​​the bed is 0.02 to 0.10, the distance from the top of the cylindrical section of the interlayer feed pipe to the porous tray of the same layer is 100 to 800 mm, and the distance from the bottom of the constricting funnel of the interlayer feed pipe to the porous tray of the next layer is 50 to 400 mm; the porosity of each porous tray is 0.5 to 5.0%; and the porosity of the gas distribution plate is 0.2 to 2.0%.

4. The low-rank pulverized coal pyrolysis and cracking conversion system according to claim 1, wherein, The cooling device has multiple perforated trays evenly distributed from top to bottom inside its shell; each perforated tray is provided with an interlayer drop pipe, which includes a cylindrical tube and a tapering funnel connected sequentially from top to bottom. The nitrogen inlet pipe is connected to the lower shell wall of the bottom porous tray of the cooling device, and a gas distribution plate is provided in the shell between the nitrogen inlet pipe and the bottom porous tray of the cooling device. The cooling device is also equipped with an internal cyclone separator and an external cyclone separator; the internal and external cyclone separators are used to discharge the high-temperature nitrogen gas inside the cooling device to the high-temperature nitrogen gas outlet pipe. Preferably, the vertical multilayer fluidized bed of the cooling device has 2 to 6 layers, a diameter of 0.5 to 10 m, and a distance of 200 to 1300 mm between adjacent porous trays; the ratio of the cross-sectional area of ​​the cylindrical section of the interlayer feed pipe to the cross-sectional area of ​​the bed is 0.02 to 0.10, the distance from the top of the cylindrical section of the interlayer feed pipe to the porous tray of the same layer is 100 to 1100 mm, and the distance from the bottom of the constricting funnel of the interlayer feed pipe to the porous tray of the next layer is 50 to 500 mm; the porosity of each porous tray is 0.5 to 5.0%; and the porosity of the gas distribution plate is 0.2 to 2.0%.

5. The low-rank pulverized coal pyrolysis and cracking conversion system according to claim 1, wherein, The direct cracking conversion reactor is a vertical multi-layer fluidized bed for direct cracking conversion. The vertical multi-layer fluidized bed for direct cracking conversion is equipped with a shell, a raw coal gas inlet pipe, an oxygen + water vapor inlet pipe, a catalyst feed pipe, a spent catalyst outlet pipe, and a cracked conversion gas outlet pipe. The shell of the direct cracking conversion vertical multilayer fluidized bed is evenly distributed with multiple porous trays from top to bottom; each porous tray is provided with an interlayer downcomer, which includes a cylindrical tube and a tapering funnel connected sequentially from top to bottom; The raw coal gas inlet pipe is connected to the lower shell wall of the bottom porous tray of the direct cracking and conversion vertical multilayer fluidized bed, and a gas distribution plate is provided in the shell between the raw coal gas inlet pipe and the bottom porous tray of the direct cracking and conversion vertical multilayer fluidized bed; the outlet of the raw coal gas outlet pipe of the pyrolysis unit is connected to the inlet of the raw coal gas inlet pipe of the direct cracking and conversion vertical multilayer fluidized bed. The oxygen and water vapor inlet pipe is connected to the shell wall between the lowest porous tray and the gas distribution plate of the vertical multilayer fluidized bed for direct cracking conversion reaction. The catalyst feed pipe is connected to the top of the shell of the vertical multilayer fluidized bed for direct cracking conversion reaction; The catalyst discharge pipe is connected to the bottom of the shell of the vertical multilayer fluidized bed for direct cracking conversion reaction; The shell of the direct cracking conversion vertical multilayer fluidized bed is also equipped with an internal cyclone separator, an external cyclone separator, and a cooling heat exchanger. The internal and external cyclone separators are used to discharge the cracked gas from the shell of the direct cracking conversion vertical multilayer fluidized bed to the heat source inlet of the cooling heat exchanger. The heat source outlet of the cooling heat exchanger is connected to the outside of the system through the cracked gas outlet pipe. Preferably, the vertical multilayer fluidized bed of the direct cracking conversion reaction has 3 to 10 layers, a diameter of 0.5 to 10 m, and a distance of 200 to 1000 mm between adjacent porous trays; the ratio of the cross-sectional area of ​​the cylindrical section of the interlayer feed pipe to the cross-sectional area of ​​the bed is 0.02 to 0.10, the distance from the top of the cylindrical section of the interlayer feed pipe to the porous tray of the same layer is 100 to 700 mm, and the distance from the bottom of the constricting funnel of the interlayer feed pipe to the porous tray of the next layer is 50 to 350 mm; the porosity of each porous tray is 0.5 to 5.0%; and the porosity of the gas distribution plate is 0.2 to 2.0%.

6. The low-rank pulverized coal pyrolysis and cracking conversion system according to claim 1, wherein, The direct cracking conversion reactor is a direct cracking conversion U-shaped tube fluidized bed, which includes a shell, a raw coal gas inlet pipe, an oxygen + water vapor inlet pipe, a catalyst feed tank, a catalyst feed pipe, a bottom coal gas inlet pipe, a gas-solid separator, a cyclone separator, a cooling heat exchanger, and a cracked conversion gas outlet pipe. The shell of the direct cracking conversion reaction U-shaped tubular fluidized bed is provided with a downward section, a U-shaped bend section and an upward section, wherein the U-shaped bend section is the connecting section between the downward section and the upward section; The raw coal gas inlet pipe and the oxygen + water vapor inlet pipe are connected together to the upper side wall inlet of the downward section; the outlet of the catalyst feeding tank is connected to the top inlet of the downward section; the catalyst feed pipe is connected to the inlet of the catalyst feeding tank; The bottom gas inlet pipe is connected to the U-shaped elbow section; The gas-solid separator is located at the outlet of the upward section. The gas-solid separator is connected to a catalyst discharge pipe and a gas outlet pipe. The gas outlet pipe is connected to the inlet of the cyclone separator. The cyclone separator is provided with a gas outlet and a solid outlet. The gas outlet is connected to the outside of the system in sequence through the heat source inlet and outlet of the cooling heat exchanger and the cracked conversion gas outlet pipe. Preferably, the diameter of the down section is 100-800mm and the height is 5-30m; the diameter of the up section is 150-1000mm and the height is 4-25m; the horizontal distance between the centerlines of the up section and the down section is 500-3000mm.

7. The low-rank pulverized coal pyrolysis and cracking conversion system according to claim 5 or 6, wherein, The catalyst carbon deposition oxidation combustion regeneration device includes a catalyst buffer tank, a riser oxidation combustion regeneration unit, and a turbulent fluidized bed oxidation regeneration sub-unit. The catalyst buffer tank is equipped with a feed inlet for the generated catalyst, a nitrogen inlet for gravity flow, a catalyst outlet for the generated catalyst, and a top inlet. The feed inlet for the generated catalyst is connected to the catalyst discharge pipe. The nitrogen inlet for gravity flow is located at the bottom of the catalyst buffer tank. When the direct cracking conversion reactor is a U-shaped tubular fluidized bed, the top inlet is connected to the solid outlet of the cyclone separator of the U-shaped tubular fluidized bed. When the direct cracking conversion reactor is a vertical multilayer fluidized bed, the top inlet is connected to the shell wall of the vertical multilayer fluidized bed. The riser oxidation combustion regenerator is provided with a vertical tubular shell, and the bottom end of the vertical tubular shell is provided with a catalyst inlet, a primary air inlet and a secondary air inlet; the catalyst inlet of the vertical tubular shell is connected to the catalyst outlet of the catalyst buffer tank; The turbulent fluidized bed oxidation regeneration sub-device is equipped with a shell, an air inlet pipe, a fresh catalyst feed pipe, a regenerated catalyst discharge pipe, a cooling heat exchanger, and a flue gas outlet pipe. Inside the shell of the turbulent fluidized bed oxidation regeneration sub-device are a hollow cylinder, a rapid separator, and an internal cyclone separator, with the rapid separator and internal cyclone separator located at the top of the hollow cylinder. The top end of the vertical tubular shell of the riser oxidation combustion regenerator passes through the hollow cylinder and communicates with the rapid separator, which discharges the material inside the vertical tubular shell into the hollow cylinder. The regenerated catalyst discharge pipe and the fresh catalyst feed pipe are connected to the bottom of the hollow cylinder wall, with the regenerated catalyst discharge pipe located below the fresh catalyst feed pipe. The air inlet pipe is connected to the wall of the hollow cylinder located between the regenerated catalyst discharge pipe and the fresh catalyst feed pipe. The outlet of the regenerated catalyst discharge pipe of the turbulent fluidized bed oxidation regeneration sub-unit is connected to the inlet of the catalyst feed pipe of the direct cracking conversion reactor; the internal cyclone separator inside the shell is used to send the flue gas in the hollow straight cylinder to the heat source inlet of the cooling heat exchanger, and the heat source outlet of the cooling heat exchanger is connected to the outside of the system through the flue gas outlet pipe; preferably, the diameter of the vertical tubular shell is 200-800 mm and the height is 5-30 m; the diameter of the hollow straight cylinder is 800-5000 mm and the height is 2-8 m.

8. A method for the pyrolysis and cracking conversion of low-rank pulverized coal, characterized in that, The method employs the system described in any one of claims 1 to 7, and includes the following steps: S1: Low-rank pulverized coal is fed into the uppermost fluidized bed of the drying device through the low-rank pulverized coal feed pipe, and high-temperature nitrogen from the cooling device is fed into the lowermost fluidized bed of the drying device, so that the low-rank pulverized coal and high-temperature nitrogen exchange heat in the fluidized state to obtain dry coal powder and moisture-containing nitrogen. The dried coal powder is fed into the uppermost fluidized bed of the pyrolysis device, so that the dried coal powder comes into contact with the high-temperature combustion gas in a fluidized state, thereby allowing the dried coal powder to obtain heat and undergo a pyrolysis reaction. Raw coal gas is generated in the uppermost fluidized bed of the pyrolysis device, and semi-coke powder is generated in the second to fifth fluidized beds from the bottom of the pyrolysis device. A portion of the semi-coke powder is fed downwards layer by layer into the pyrolysis unit, where it comes into contact with oxygen-containing gas in a fluidized state and undergoes an oxidation and combustion reaction to generate ash powder and the high-temperature combustion gas. The ash powder is then discharged from the system. The remaining semi-coke powder is fed into the uppermost fluidized bed of the cooling unit, where it exchanges heat with nitrogen gas fed into the cooling unit in a fluidized state to obtain the high-temperature nitrogen gas and the semi-coke powder product. The semi-coke powder product is then discharged from the system. S2: The raw coal gas is sent to the direct cracking and conversion reactor, where it undergoes cracking and conversion under the action of oxygen, steam and catalyst to obtain cracked conversion gas and a spent catalyst; the spent catalyst is sent to the catalyst carbonization oxidation combustion regeneration device for treatment to obtain a regenerated catalyst, which is then sent back to the direct cracking and conversion reactor for use.

9. The method for pyrolysis and cracking conversion of low-rank pulverized coal according to claim 8, wherein, In step S1: Low-rank pulverized coal is fed into the uppermost fluidized bed of the drying device through the low-rank pulverized coal feed pipe using a screw feeder. The low-rank pulverized coal has a moisture content of 16-30% and a particle size of 0.01-1.0 mm. The height of the fluidized bed formed by the low-rank pulverized coal and the high-temperature nitrogen is 300-800 mm. The operating temperature of the uppermost fluidized bed in the drying device shall not be lower than 60℃, and the operating temperature of the lowermost fluidized bed in the drying device shall not be lower than 200℃. The empty tower operating velocity of high-temperature nitrogen in each fluidized bed is controlled at 0.2–0.6 m / s; The average residence time of the low-rank pulverized coal in the drying device is 20–100 min; The moisture content of the dried coal powder is 5.0–8.0%. High-temperature nitrogen gas from the cooling unit is sequentially fed into the lowest fluidized bed of the drying unit through a high-temperature nitrogen gas outlet pipe, a high-temperature nitrogen gas inlet pipe, and a gas distribution plate. The method further includes discharging the moisture-containing nitrogen gas from the system by sequentially passing it through an inner cyclone separator and an outer cyclone separator; The operating temperature of the uppermost fluidized bed in the pyrolysis unit is 400–500℃; The operating temperature of the second to fifth fluidized bed layers from the bottom of the pyrolysis unit is 550–650°C. The operating temperature of the lowest fluidized bed in the pyrolysis unit is 600–800℃; The empty tower operating gas velocity of the high-temperature combustion gas in each fluidized bed is controlled at 0.2–0.6 m / s; The average residence time of the dried coal powder in the pyrolysis device is 30 to 200 minutes; The operating temperature of the uppermost fluidized bed inside the cooling device shell shall not be lower than 300℃; The operating temperature of the lowest fluidized bed inside the cooling device casing shall not exceed 60℃; The empty tower operating velocity of nitrogen in each fluidized bed is controlled at 0.2–0.6 m / s; The average residence time of the remaining semi-coke powder in the cooling device is 10 to 100 minutes.

10. The method for pyrolysis and cracking conversion of low-rank pulverized coal according to claim 8, wherein, In step S2: The catalyst is at least one of molecular sieve, alumina, graphite, magnesium oxide and iron oxide; When the direct cracking conversion reactor is a U-shaped fluidized bed direct cracking conversion reactor, the cracking conversion of raw coal gas includes: mixing the raw coal gas, oxygen, steam, and catalyst, and sequentially passing them through a downward section, a U-shaped bend section, and an upward section in a fluidized state, causing the tar components in the raw coal gas to undergo catalytic cracking and conversion reactions, obtaining a gas-solid mixture system, which is then separated by a gas-solid separator to obtain solid-containing cracked conversion gas and the catalyst to be generated; the solid-containing cracked conversion gas is then sent to the cyclone separator for further processing to obtain the desired product. The pyrolysis conversion gas and catalyst powder are described; the pyrolysis conversion gas is cooled and sent outside the system; the raw catalyst and catalyst powder are sent to the catalyst buffer tank; preferably, the operating temperature of the downward section is 400-480℃, the gas velocity in the empty tower of the downward section is 3-15m / s, the operating temperature of the upward section is 450-550℃, the gas velocity in the empty tower of the upward section is 3-10m / s, and the average residence time of raw coal gas in the U-shaped tubular fluidized bed of direct cracking conversion reaction is 3-20s; When the direct cracking conversion reactor is a vertical multi-layer fluidized bed reactor, the cracking conversion of raw coal gas includes: feeding a catalyst into the uppermost fluidized bed of the U-shaped tube fluidized bed, and feeding raw coal gas, oxygen, and steam into the lowermost fluidized bed of the U-shaped tube fluidized bed, so that the tar components in the raw coal gas undergo catalytic cracking and conversion reactions in a fluidized state, obtaining the cracked conversion gas and the catalyst to be generated; the cracked conversion gas is then cooled and sent outside the system. The catalyst to be generated is sent to the catalyst buffer tank; preferably, the operating temperature of the uppermost fluidized bed of the direct cracking conversion vertical multilayer fluidized bed is 350-450℃, the operating temperature of the lowermost fluidized bed of the direct cracking conversion vertical multilayer fluidized bed is 450-600℃, the empty tower operating gas velocity of the raw coal gas in each fluidized bed is controlled at 0.2-0.5m / s, and the average residence time of the catalyst in the direct cracking conversion vertical multilayer fluidized bed is 1-10min; Inside the catalyst buffer tank, the spent catalyst flows under the action of nitrogen into the vertical tubular shell of the riser oxidation combustion regenerator. Inside the vertical tubular shell, the spent catalyst and catalyst powder react with air entering through the primary air inlet in a fluidized state, undergoing oxidation and combustion reactions of the carbon deposited on the catalyst surface. The resulting reaction system flows upward under the action of air entering through the secondary air inlet into the rapid separator within the turbulent fluidized bed oxidation regenerator, and then through the rapid separator into the hollow cylinder of the turbulent fluidized bed oxidation regenerator. Inside the hollow cylinder, the reaction... The system undergoes an oxidation reaction with air to obtain a regenerated catalyst. The regenerated catalyst and optionally a fresh catalyst are fed into a direct cracking conversion reactor. Preferably, the operating gas velocity of nitrogen in the catalyst buffer tank is 0.1–0.2 m / s; the air velocity in the riser oxidation combustion regenerator is 3–10 m / s, and the operating temperature is 450–600°C; the air velocity in the turbulent fluidized bed oxidation regenerator is 0.2–0.6 m / s, and the operating temperature is 450–600°C; the amount of coke deposited on the regenerated catalyst is less than 0.2% based on the total weight of the regenerated catalyst.

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