A method and system for heating and cooling polycrystalline silicon cold hydrogenation

Abstract

This invention discloses a method and system for cooling and heating polycrystalline silicon cold hydrogenation, relating to the field of polycrystalline silicon production technology, including the following steps: S1, mixing hydrogen and silicon tetrachloride, then feeding the mixture into a material heating line for vaporization and stepped heat exchange heating, followed by feeding the mixture into a fluidized bed; S2, in the fluidized bed, high-temperature hydrogen, silicon tetrachloride, and silicon powder react to generate trichlorosilane, and feeding the trichlorosilane, unreacted silicon tetrachloride, and hydrogen high-temperature mixture in the fluidized bed into a material cooling line; S3, the material cooling line performs stepped heat exchange cooling, silicon powder filtration, and washing on the high-temperature mixture, and finally feeds the cooled material into the downstream device; S4, when the cold hydrogenation cooling and heating system needs to be shut down for maintenance after a period of operation, a stepped cooling method combined with the material heating line is used to cool the fluidized bed, resulting in uniform and faster cooling.

Description

Technical Field

[0001] This invention relates to the field of polycrystalline silicon production technology, and more specifically to a method and system for heating and cooling polycrystalline silicon cold hydrogenation. Background Technology

[0002] Currently, the technology used in my country's polysilicon production is primarily the modified Siemens process. Polysilicon produced using this technology accounts for over 80% of the country's total output. A crucial step in the modified Siemens process is cold hydrogenation. Cold hydrogenation involves mixing and heating hydrogen and silicon tetrachloride in a fluidized bed reactor at 530℃-560℃ and 2.5MPa-3.0MPa, where they undergo an endothermic reaction with silicon powder. This reaction requires the addition of a certain proportion of catalyst to improve the conversion rate. The exhaust gas from the reaction undergoes heat recovery, dust removal, washing, and condensation to obtain chlorosilane products, which are then sent to the distillation process for further processing. Unreacted hydrogen is compressed and reused using a circulating hydrogen compressor. The advent of cold hydrogenation effectively converts silicon tetrachloride into trichlorosilane, solving the closed-loop chlorine cycle problem and reducing the overall power consumption of polysilicon production. It is a significant cost-reduction approach in the modified Siemens process for polysilicon production.

[0003] In the prior art, patent CN115340095A discloses a cold hydrogenation heat energy recovery system and method, including a feed gas preheating mechanism, a feed gas mixing and vaporization group, a mixed gas heating mechanism, a fluidized bed, a quench tower, and a coarse separator. The feed gas preheating mechanism has a first shell-side flow channel and a first tube-side flow channel for heat exchange, and the mixed gas heating mechanism has a second shell-side flow channel and a second tube-side flow channel for heat exchange. The inlet of the first tube-side flow channel is connected to a gas supply source, the outlet of the first tube-side flow channel is connected to the inlet of the feed gas mixing and vaporization group, the outlet of the feed gas mixing and vaporization group is connected to the inlet of the second shell-side flow channel, the outlet of the second shell-side flow channel is connected to the gas inlet of the fluidized bed, the outlet of the fluidized bed is connected to the inlet of the second tube-side flow channel, the inlet of the second tube-side flow channel is connected to the inlet of the quench tower, the outlet of the quench tower is connected to the inlet of the first shell-side flow channel, and the outlet of the first shell-side flow channel is connected to the coarse separator. This invention realizes cold hydrogenation heat energy recovery, reduces heat waste, and lowers energy consumption and production costs.

[0004] The cold hydrogenation heat recovery system disclosed in the above patent has the following drawbacks:

[0005] 1. The proposed solution does not take into account the start-up and shutdown cooling time of the cold hydrogenation process. The simultaneous operation of the three-stage heat exchangers results in an excessively long shutdown cooling time for the cold hydrogenation process, increasing the maintenance cost of the cold hydrogenation process.

[0006] 2. After passing through three stages of heat exchange, the fluidized bed outlet enters the quench tower. Without removing silicon powder, this will cause blockage of the quench tower and shorten the cold hydrogenation operation cycle.

[0007] 3. Using ordinary shell and tube heat exchangers for heat recovery requires a large number of heat exchange stages, and the heat exchangers are prone to clogging. Summary of the Invention

[0008] In order to overcome the defects in the prior art, the present invention discloses a polycrystalline silicon cold hydrogenation heating and cooling method and system to solve the problems of shutdown cooling and silicon powder removal in the prior art.

[0009] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0010] In a first aspect, the present invention provides a method for heating and cooling polycrystalline silicon cold hydrogenation, comprising the following steps:

[0011] S1. Mix hydrogen and silicon tetrachloride, and then send the mixture into the material heating line. Use a vaporizer and a multi-stage heat recovery unit to vaporize the mixture and perform step heat exchange to raise the temperature. Then send the mixture into a fluidized bed.

[0012] S2. In the fluidized bed, high-temperature hydrogen, silicon tetrachloride and silicon powder react to generate trichlorosilane, and the high-temperature mixture of trichlorosilane, unreacted silicon tetrachloride and hydrogen in the fluidized bed is sent into the material cooling line.

[0013] S3, the material cooling line performs stepped heat exchange cooling, silicon powder filtration and washing on the high-temperature mixture, and sends the finally stepped heat exchanged and cooled material to the downstream unit.

[0014] S4. When the cold hydrogenation heating and cooling operation needs to be stopped for maintenance after a period of time, a stepped cooling method is adopted in combination with the material heating line to cool down the fluidized bed.

[0015] Preferably, step S1 includes the following steps:

[0016] S11. The hydrogen and silicon tetrachloride transported by the hydrogen pipeline and silicon tetrachloride pipeline are fed into the mixer for mixing.

[0017] S12. The mixture after mixing in the mixer is sent into the shell-side flow channel of the primary heat recovery unit to perform the first heat exchange and temperature rise of the mixture from T1 to T2.

[0018] S13. The mixture after the first heat exchange and heating is sequentially fed into the vaporizer and superheater for vaporization and heating, raising the temperature of the mixture from T2 to T3.

[0019] S14. The vaporized and heated mixture is fed into the shell-side flow channel of the secondary heat recovery unit to perform a second heat exchange and temperature increase on the mixture, raising the temperature of the mixture from T3 to T4.

[0020] S15. The mixture after the second heat exchange and heating is sent into the shell-side flow channel of the three-stage heat recovery unit to perform a third heat exchange and heating, raising the temperature of the mixture from T4 to T5.

[0021] S16. The mixture after the third heat exchange and heating is sent into the shell-side flow channel of the fourth-stage heat recovery unit to perform the fourth heat exchange and heating of the mixture, raising the temperature of the mixture from T5 to T6.

[0022] S17. The mixture after the fourth heat exchange and heating is sent to the electric heater to electrically heat the mixture, raising its temperature from T6 to T7, and then sent to the bottom of the fluidized bed.

[0023] Preferably, in the material heating circuit of step S1, T1 is 50-60℃, T2 is 100-120℃, T3 is 150-170℃, T4 is 220-240℃, T5 is 310-330℃, T6 is 470-490℃, and T7 is 560℃.

[0024] Preferably, in step S2, silicon powder is introduced into the fluidized bed, and high-temperature hydrogen and silicon tetrachloride react with the silicon powder. 23%-35% of the silicon tetrachloride reacts to generate trichlorosilane. The trichlorosilane, unreacted silicon tetrachloride, and hydrogen are then mixed at high temperature and fed into the material cooling circuit.

[0025] Preferably, step S3 includes the following steps:

[0026] S31. The high-temperature mixture at the top of the fluidized bed is fed into the tube flow channel of the four-stage heat recovery unit to perform the first heat exchange and cooling of the high-temperature mixture, reducing the temperature of the high-temperature mixture from M1 to M2.

[0027] S32. The high-temperature mixture after the first heat exchange and cooling is sent into the tube flow channel of the three-stage heat recovery unit to perform a second heat exchange and cooling, reducing the temperature of the high-temperature mixture from M2 to M3.

[0028] S33. The high-temperature mixture after the second heat exchange and cooling is sequentially fed into a cyclone separator and a filter to remove silicon powder;

[0029] S34. The high-temperature mixture after removing silicon powder is sent into the tube flow channel of the secondary heat recovery unit to perform a third heat exchange and cooling of the high-temperature mixture, reducing the temperature of the high-temperature mixture from M3 to M4.

[0030] S35. The high-temperature mixture after the third heat exchange and cooling is sequentially fed into washing tower I and washing tower II for washing and cooling, so that the temperature of the mixture is reduced from M4 to M5.

[0031] S36. The washed and cooled mixture is sent to the tube side of the primary heat recovery unit for the fourth heat exchange and cooling, reducing the temperature of the mixture from M5 to M6, and finally sent to the downstream unit.

[0032] Preferably, in the material cooling circuit of step S3, M1 is 550℃, M2 is 370-490℃, M3 is 300-320℃, M4 is 220-240℃, M5 is 130-150℃, and M6 is 80-100℃.

[0033] Preferably, step S4 includes the following steps:

[0034] S41. Open the bypass valve I of the three-stage heat recovery unit so that most of the low-temperature material in the material heating line does not enter the shell-side flow channel of the three-stage heat recovery unit, but directly enters the shell-side flow channel of the subsequent four-stage heat recovery unit through valve I, thereby bypassing the three-stage heat recovery unit to cool it down, and controlling the cooling rate of the bottom of the fluidized bed to N1.

[0035] S42. When the cooling rate at the bottom of the fluidized bed is lower than that of N2, open the bypass valve II of the secondary heat recovery unit so that most of the low-temperature material in the material heating line does not enter the shell-side flow channel of the secondary heat recovery unit, but directly enters the fluidized bed through valve II to cool the fluidized bed.

[0036] S43. When the cooling rate at the bottom of the fluidized bed is lower than N3, close valve III on the hydrogen delivery pipeline that controls the hydrogen entering the material heating line, and open valve IV that controls the hydrogen entering the first heat exchanger, so that the hydrogen in the hydrogen delivery pipeline enters the tube flow channel of the first heat exchanger, cools the hydrogen and then directly introduces it into the fluidized bed to continue cooling the inside of the fluidized bed.

[0037] S44. When the cooling rate at the bottom of the fluidized bed is lower than N4, close valve IV and open valve V, which controls the entry of hydrogen into the second heat exchanger, so that the hydrogen in the hydrogen delivery pipeline enters the tube-side flow channel of the second heat exchanger, cools the hydrogen, and then directly introduces it into the fluidized bed to continue cooling the inside of the fluidized bed until the system cooling is complete; wherein, the heat exchange temperature of the first heat exchanger is greater than the heat exchange temperature of the second heat exchanger.

[0038] Preferably, in step S4, N1 is 40-60℃ / h, N2 is 40℃ / h, N3 is 40℃ / h, and N4 is 40℃ / h; the first heat exchanger is a circulating water heat exchanger, and the second heat exchanger is a 7℃ heat exchanger.

[0039] In a second aspect, the present invention provides a polycrystalline silicon cold hydrogenation heating and cooling system, including a mixer, a heat recovery assembly, a fluidized bed, a scrubbing tower assembly, a vaporization superheating assembly, a silicon powder filtration assembly, and a shutdown cooling assembly.

[0040] The mixer is connected to a hydrogen delivery pipeline and a silicon tetrachloride delivery pipeline at its inlet. The heat recovery assembly includes several stages of heat recovery units connected in sequence. Each stage of heat recovery unit is equipped with a shell-side flow channel and a tube-side flow channel for heat exchange. The shell-side flow channels of the several stages of heat recovery units form a material heating line, and the tube-side flow channels form a material cooling line.

[0041] In the material heating circuit, the shell-side flow channel inlet of the first-stage heat recovery unit is connected to the outlet of the mixer, the shell-side flow channel outlet of the previous-stage heat recovery unit is connected to the shell-side flow channel inlet of the next-stage heat recovery unit, and the shell-side flow channel outlet of the last-stage heat recovery unit is connected to the bottom inlet of the fluidized bed.

[0042] In the material cooling circuit, the tube-side flow channel inlet of the final stage heat recovery unit is connected to the top outlet of the fluidized bed, the tube-side flow channel outlet of the next stage heat recovery unit is connected to the tube-side flow channel inlet of the previous stage heat recovery unit, and the tube-side flow channel outlet of the second stage heat recovery unit is connected to the inlet of the washing tower assembly, which includes several washing towers connected in sequence.

[0043] The vaporization superheating assembly is installed in the material heating line, the silicon powder filtration assembly is installed in the material cooling line, and one end of the shutdown cooling assembly is connected to the hydrogen conveying pipeline, and the other end is connected to the material heating line and the bottom inlet of the fluidized bed.

[0044] Preferably, the heat recovery assembly includes a primary heat recovery unit, a secondary heat recovery unit, a tertiary heat recovery unit, and a quaternary heat recovery unit;

[0045] The shell-side flow channel inlet of the first-stage heat recovery unit is connected to the outlet of the mixer; the shell-side flow channel outlet of the first-stage heat recovery unit is connected to the shell-side flow channel inlet of the second-stage heat recovery unit; the shell-side flow channel outlet of the second-stage heat recovery unit is connected to the shell-side flow channel inlet of the third-stage heat recovery unit; the shell-side flow channel outlet of the third-stage heat recovery unit is connected to the shell-side flow channel inlet of the fourth-stage heat recovery unit; and the shell-side flow channel outlet of the fourth-stage heat recovery unit is connected to the bottom inlet of the fluidized bed.

[0046] The fluidized bed top outlet is connected to the tube-side flow channel inlet of the fourth-stage heat recovery unit, the tube-side flow channel outlet of the fourth-stage heat recovery unit is connected to the tube-side flow channel inlet of the third-stage heat recovery unit, the tube-side flow channel outlet of the third-stage heat recovery unit is connected to the tube-side flow channel inlet of the second-stage heat recovery unit, and the tube-side flow channel outlet of the second-stage heat recovery unit is connected to the combined inlet of the scrubbing tower.

[0047] Preferably, the vaporization superheating assembly is arranged in the material heating line between the shell-side flow channel outlet of the primary heat recovery unit and the shell-side flow channel inlet of the secondary heat recovery unit, and includes a vaporizer and a superheater.

[0048] The vaporizer inlet is connected to the shell-side flow channel outlet of the first-stage heat recovery unit, the vaporizer outlet is connected to the superheater inlet, and the superheater outlet is connected to the shell-side flow channel inlet of the second-stage heat recovery unit.

[0049] Preferably, it also includes an electric heater, wherein the shell-side flow channel outlet of the fourth-stage heat recovery unit is connected to the inlet of the electric heater, and the outlet of the electric heater is connected to the bottom inlet of the fluidized bed.

[0050] Preferably, the silicon powder filter assembly is arranged in the material cooling line between the outlet of the tube-side flow channel of the tertiary heat recovery unit and the inlet of the tube-side flow channel of the secondary heat recovery unit, and includes a cyclone separator and a filter;

[0051] The cyclone separator inlet is connected to the outlet of the tube-side flow channel of the third-stage heat recovery unit, the cyclone separator outlet is connected to the filter inlet, and the filter outlet is connected to the inlet of the tube-side flow channel of the second-stage heat recovery unit.

[0052] Preferably, the washing tower assembly includes washing tower I and washing tower II. The bottom inlet of washing tower I is connected to the tube-side flow channel outlet of the secondary heat recovery unit, the top outlet of washing tower I is connected to the bottom inlet of washing tower II, the top outlet of washing tower II is connected to the tube-side flow channel inlet of the primary heat recovery unit, and the tube-side flow channel outlet of the primary heat recovery unit is connected to the downstream device.

[0053] Preferably, the shutdown cooling combination includes a first heat exchanger and a second heat exchanger connected in parallel, the heat exchange temperature of the first heat exchanger is greater than that of the second heat exchanger, the inlet pipes of the first heat exchanger and the second heat exchanger are connected to the hydrogen delivery pipeline, and the outlet pipes are connected to the bottom inlet of the fluidized bed.

[0054] Preferably, a first pipe connecting the inlet and outlet is provided between the shell-side flow channel inlet and outlet of the three-stage heat recovery unit, and a valve I is provided on the first pipe;

[0055] The outlet main pipes of the first heat exchanger and the second heat exchanger are connected to a second pipe, which is connected to the inlet of the shell-side flow channel of the secondary heat recovery unit. Valve II is installed on the second pipe.

[0056] The hydrogen delivery pipeline is equipped with valve III for controlling the entry of materials into the mixer;

[0057] Valves IV and V are respectively installed on the inlet branch pipes of the first heat exchanger and the second heat exchanger.

[0058] Preferably, the first heat exchanger is a circulating water heat exchanger, and the second heat exchanger is a 7°C heat exchanger.

[0059] The beneficial effects of this invention are:

[0060] The cold hydrogenation heating and cooling method and system provided by this invention employs a stepped cooling method for shutdown cooling, resulting in uniform and faster cooling, effectively saving shutdown maintenance time and reducing costs. It utilizes low-temperature hydrogen and low-temperature materials in the material heating line to rapidly cool the fluidized bed, quickly cooling down cold hydrogenation shutdowns, saving cold hydrogenation maintenance time and reducing maintenance costs.

[0061] The cold hydrogenation heating and cooling method and system provided by this invention filters silicon powder entering the material cooling circuit from the fluidized bed, preventing silicon powder from affecting subsequent systems and effectively removing silicon powder, thus extending the system's operating cycle. The washing tower assembly includes several washing towers connected in sequence, providing better multi-stage washing and effectively improving product quality.

[0062] The cold hydrogenation heating and cooling method and system provided by this invention includes a heat recovery assembly comprising several stages of heat recovery units connected in sequence. Each stage of the heat recovery unit is equipped with a shell-side flow channel and a tube-side flow channel for heat exchange. The temperature of the fluid in the shell-side flow channel is lower than that of the fluid in the tube-side flow channel. The fluids in the shell-side and tube-side flow channels exchange heat with each other to recover and utilize the heat of the fluid in the tube-side flow channel, thereby raising the temperature of the fluid in the shell-side flow channel and lowering the temperature of the fluid in the tube-side flow channel. The shell-side flow channels of the several stages of heat recovery units form a material heating path, and the tube-side flow channels form a material cooling path, realizing the heating, cooling, and heat recovery of polycrystalline silicon cold hydrogenation. Attached Figure Description

[0063] Figure 1 This is a schematic diagram of the polycrystalline silicon cold hydrogenation heating and cooling method of the present invention;

[0064] Figure 2 This is a schematic diagram of the polycrystalline silicon cold hydrogenation heating and cooling system of the present invention;

[0065] Figure label:

[0066] 1. Mixer; 2. Fluidized bed; 3. Primary heat recovery unit; 4. Secondary heat recovery unit; 5. Tertiary heat recovery unit; 6. Quaternary heat recovery unit; 7. Vaporizer; 8. Superheater; 9. Electric heater; 10. Cyclone separator; 11. Filter; 12. Scrubber I; 13. Scrubber II; 14. First heat exchanger; 15. Second heat exchanger; 16. Valve I; 17. Valve II; 18. Valve III; 19. Valve IV; 20. Valve V. Detailed Implementation

[0067] The following will provide a clear and complete description of the concept, specific structure, and technical effects of the present invention in conjunction with the embodiments and accompanying drawings, so as to fully understand the purpose, features, and effects of the present invention.

[0068] Example 1

[0069] A polycrystalline silicon cold hydrogenation heating and cooling system, such as Figure 2 As shown, it includes a mixer 1, a heat recovery assembly, a fluidized bed 2, a scrubbing tower assembly, a vaporization superheating assembly, a silicon powder filtration assembly, and a shutdown cooling assembly.

[0070] The inlet of the mixer 1 is connected to a hydrogen delivery pipeline and a silicon tetrachloride delivery pipeline. The heat recovery assembly includes several stages of heat recovery units connected in sequence. Each stage of heat recovery unit is equipped with a shell-side flow channel and a tube-side flow channel for heat exchange. The shell-side flow channels of the several stages of heat recovery units form a material heating line, and the tube-side flow channels form a material cooling line.

[0071] In the material heating circuit, the shell-side flow channel inlet of the first-stage heat recovery unit is connected to the outlet of the mixer 1, the shell-side flow channel outlet of the preceding heat recovery unit is connected to the shell-side flow channel inlet of the following heat recovery unit, and the shell-side flow channel outlet of the final-stage heat recovery unit is connected to the bottom inlet of the fluidized bed 2.

[0072] In the material cooling circuit, the tube-side flow channel inlet of the final stage heat recovery unit is connected to the top outlet of the fluidized bed 2, the tube-side flow channel outlet of the subsequent stage heat recovery unit is connected to the tube-side flow channel inlet of the previous stage heat recovery unit, and the tube-side flow channel outlet of the second stage heat recovery unit is connected to the inlet of the washing tower assembly, which includes several washing towers connected in sequence.

[0073] The vaporization superheating assembly is installed in the material heating line, the silicon powder filtration assembly is installed in the material cooling line, and one end of the shutdown cooling assembly is connected to the hydrogen conveying pipeline, and the other end is connected to the material heating line and the bottom inlet of the fluidized bed 2.

[0074] In this embodiment, mixer 1 is used to mix hydrogen and silicon tetrachloride transported by the hydrogen delivery pipeline and the silicon tetrachloride delivery pipeline. The heat recovery assembly is used to exchange heat between the materials, heating or cooling them, and recovering and utilizing the heat. Fluidized bed 2 is used for the reaction of hydrogen, silicon tetrachloride, and silicon powder to produce trichlorosilane. The scrubbing tower assembly is used to wash the materials. The vaporization superheating assembly is used to vaporize and superheat the mixed hydrogen and silicon tetrachloride gas. The silicon powder filtration assembly is used to filter silicon powder to prevent it from affecting subsequent systems. The shutdown cooling assembly is used for cooling during cold hydrogenation shutdown.

[0075] In this embodiment, the heat recovery assembly includes several stages of heat recovery units connected in sequence. Each stage of the heat recovery unit is equipped with a shell-side flow channel and a tube-side flow channel for heat exchange. The temperature of the fluid in the shell-side flow channel is lower than that of the fluid in the tube-side flow channel. The fluids in the shell-side and tube-side flow channels exchange heat with each other to recover and utilize the heat of the fluid in the tube-side flow channel, thereby raising the temperature of the fluid in the shell-side flow channel and lowering the temperature of the fluid in the tube-side flow channel. The shell-side flow channels of the several stages of heat recovery units form a material heating path, and the tube-side flow channels form a material cooling path, realizing the heating, cooling and heat recovery of polycrystalline silicon cold hydrogenation.

[0076] like Figure 2 As shown, the heat recovery assembly includes a primary heat recovery unit 3, a secondary heat recovery unit 4, a tertiary heat recovery unit 5, and a quaternary heat recovery unit 6.

[0077] The shell-side flow channel inlet of the first-stage heat recovery unit 3 is connected to the outlet of the mixer 1, the shell-side flow channel outlet of the first-stage heat recovery unit 3 is connected to the shell-side flow channel inlet of the second-stage heat recovery unit 4, the shell-side flow channel outlet of the second-stage heat recovery unit 4 is connected to the shell-side flow channel inlet of the third-stage heat recovery unit 5, the shell-side flow channel outlet of the third-stage heat recovery unit 5 is connected to the shell-side flow channel inlet of the fourth-stage heat recovery unit 6, and the shell-side flow channel outlet of the fourth-stage heat recovery unit 6 is connected to the bottom inlet of the fluidized bed 2.

[0078] The top outlet of the fluidized bed 2 is connected to the inlet of the tube-side flow channel of the fourth-stage heat recovery unit 6. The outlet of the tube-side flow channel of the fourth-stage heat recovery unit 6 is connected to the inlet of the tube-side flow channel of the third-stage heat recovery unit 5. The outlet of the tube-side flow channel of the third-stage heat recovery unit 5 is connected to the inlet of the tube-side flow channel of the second-stage heat recovery unit 4. The outlet of the tube-side flow channel of the second-stage heat recovery unit 4 is connected to the inlet of the scrubbing tower assembly.

[0079] In this embodiment, by setting up a four-stage heat recovery unit of the above form, the heat recovery rate is higher and the power consumption is lower.

[0080] like Figure 2 As shown, the vaporization superheater assembly is located in the material heating line between the shell-side flow channel outlet of the primary heat recovery unit 3 and the shell-side flow channel inlet of the secondary heat recovery unit 4, and includes a vaporizer 7 and a superheater 8.

[0081] The inlet of vaporizer 7 is connected to the shell-side flow channel outlet of primary heat recovery unit 3, the outlet of vaporizer 7 is connected to the inlet of superheater 8, and the outlet of superheater 8 is connected to the shell-side flow channel inlet of secondary heat recovery unit 4.

[0082] In this embodiment, vaporizer 7 is used to vaporize the mixture of hydrogen and silicon tetrachloride. Superheater 8 is used to reheat the mixture in vaporizer 7, making it a superheated gas.

[0083] like Figure 2 As shown, it also includes an electric heater 9. The shell-side flow channel outlet of the four-stage heat recovery unit 6 is connected to the inlet of the electric heater 9, and the outlet of the electric heater 9 is connected to the bottom inlet of the fluidized bed 2. The electric heater 9 is used to electrically heat the mixed gas of hydrogen and silicon tetrachloride.

[0084] like Figure 2 As shown, the silicon powder filter assembly is installed in the material cooling line between the outlet of the tube-side flow channel of the tertiary heat recovery unit 5 and the inlet of the tube-side flow channel of the secondary heat recovery unit 4, and includes a cyclone separator 10 and a filter 11.

[0085] The inlet of the cyclone separator 10 is connected to the outlet of the tube-side flow channel of the tertiary heat recovery unit 5, the outlet of the cyclone separator 10 is connected to the inlet of the filter 11, and the outlet of the filter 11 is connected to the inlet of the tube-side flow channel of the secondary heat recovery unit 4.

[0086] In this embodiment, the cyclone separator 10 is used to separate large silicon powder particles from the material. The filter 11 is used to filter small silicon powder particles from the material. In addition, by adding the cyclone separator 10 and the filter 11 to effectively separate the silicon powder before heat recovery, the problems of scaling and clogging in the secondary heat recovery unit 4 are avoided, thus solving the defect 3 in the background technology.

[0087] like Figure 2 As shown, the washing tower assembly includes washing tower I12 and washing tower II13. The bottom inlet of washing tower I12 is connected to the tube-side flow channel outlet of the secondary heat recovery unit 4, the top outlet of washing tower I12 is connected to the bottom inlet of washing tower II13, the top outlet of washing tower II13 is connected to the tube-side flow channel inlet of the primary heat recovery unit 3, and the tube-side flow channel outlet of the primary heat recovery unit 3 is connected to the downstream device.

[0088] In this embodiment, scrubbing tower I12 is used to remove trace amounts of silicon powder, metal chlorides, and high-boiling-point substances from the gas entering the tower. Scrubbing tower II13 is used to further scrub the gas exiting scrubbing tower I12.

[0089] like Figure 2 As shown, a spray liquid inlet pipe is installed on the side wall at the top of the washing tower II13, a spray liquid conveying pipe is installed between the bottom of the washing tower II13 and the top side wall of the washing tower I12, and a downstream slurry conveying pipe is installed at the bottom of the washing tower I12.

[0090] like Figure 2As shown, the shutdown cooling assembly includes a first heat exchanger 14 and a second heat exchanger 15 connected in parallel. The heat exchange temperature of the first heat exchanger 14 is higher than that of the second heat exchanger 15. The inlet pipes of the first heat exchanger 14 and the second heat exchanger 15 are connected to a hydrogen delivery pipeline, and the outlet pipes are connected to the bottom inlet of the fluidized bed 2. The first heat exchanger 14 and the second heat exchanger 15 are used to exchange heat with the hydrogen, and then deliver the cooled hydrogen to the fluidized bed 2 for shutdown cooling.

[0091] like Figure 2 As shown, a first pipe connecting the inlet and outlet of the shell-side flow channel of the three-stage heat recovery unit 5 is provided, and a valve I16 is provided on the first pipe. The functions of the first pipe and the valve I16 are: to close the valve I16 during the system heating process to accelerate the heating rate; to fully open the valve I16 during the system cooling process to accelerate the cooling rate; and to adjust the opening degree of the valve I16 during system operation to adjust the shell-side outlet temperature.

[0092] like Figure 2 As shown, the outlet main pipes of the first heat exchanger 14 and the second heat exchanger 15 are connected to a second pipe, which is connected to the inlet of the shell-side flow channel of the secondary heat recovery unit 4. A valve II 17 is installed on the second pipe. The functions of the second pipe and valve II 17 are: to close valve II 17 during system heating to accelerate the heating rate; to fully open valve II 17 during system cooling to accelerate the cooling rate; and to adjust the opening degree of valve II 17 during system operation to adjust the shell-side outlet temperature.

[0093] like Figure 2 As shown, the hydrogen delivery pipeline is equipped with a valve Ⅲ18 for controlling the entry of materials into the mixer 1.

[0094] like Figure 2 As shown, valves IV19 and V20 are respectively installed on the inlet branch pipes of the first heat exchanger 14 and the second heat exchanger 15 to control the hydrogen gas to enter the heat exchanger for heat exchange and to cool the hydrogen gas.

[0095] In a preferred embodiment of this invention, the first heat exchanger 14 is a circulating water heat exchanger, and the second heat exchanger 15 is a 7°C heat exchanger.

[0096] Example 2

[0097] A method for heating and cooling polycrystalline silicon cold hydrogenation, such as Figure 1 As shown, it includes the following steps:

[0098] S1. Mix hydrogen and silicon tetrachloride, and then send the mixture into the material heating line. Use a vaporizer and a multi-stage heat recovery unit to vaporize the mixture and perform step heat exchange to raise the temperature. Then send the mixture into fluidized bed 2.

[0099] S2. In fluidized bed 2, high-temperature hydrogen, silicon tetrachloride and silicon powder react to generate trichlorosilane, and the high-temperature mixture of trichlorosilane, unreacted silicon tetrachloride and hydrogen in fluidized bed 2 is sent into the material cooling line.

[0100] S3, the material cooling line performs stepped heat exchange cooling, silicon powder filtration and washing on the high-temperature mixture, and sends the finally stepped heat exchanged and cooled material to the downstream unit.

[0101] S4. When the cold hydrogenation heating and cooling operation needs to be stopped for maintenance after a period of time, a stepped cooling method is adopted in combination with the material heating line to cool down the fluidized bed 2.

[0102] like Figure 2 As shown, the material heating in step S1 includes the following steps:

[0103] S11. The hydrogen and silicon tetrachloride transported by the hydrogen pipeline and silicon tetrachloride pipeline are fed into mixer 1 for mixing.

[0104] S12. The mixture after mixing in mixer 1 is sent into the shell-side flow channel of primary heat recovery unit 3 to perform the first heat exchange and temperature rise of the mixture from 50-60℃ to 100-120℃.

[0105] S13. The mixture after the first heat exchange and heating is sequentially fed into the vaporizer 7 and the superheater 8 for vaporization and heating, raising the temperature of the mixture from 100-120℃ to 150-170℃.

[0106] S14. The vaporized and heated mixture is fed into the shell-side flow channel of the secondary heat recovery unit 4 to perform a second heat exchange and temperature increase on the mixture, raising the temperature of the mixture from 150-170℃ to 220-240℃.

[0107] S15. The mixture after the second heat exchange and heating is sent into the shell-side flow channel of the three-stage heat recovery unit 5 to perform a third heat exchange and heating, raising the temperature of the mixture from 220-240℃ to 310-330℃.

[0108] S16. The mixture after the third heat exchange and heating is sent into the shell-side flow channel of the fourth-stage heat recovery unit 6 to perform the fourth heat exchange and heating of the mixture, raising the temperature of the mixture from 310-330℃ to 470-490℃.

[0109] S17. The mixture after the fourth heat exchange and heating is sent to the electric heater 9 to electrically heat the mixture, raising its temperature from 470-490℃ to 560℃, and then sent to the bottom of the fluidized bed 2.

[0110] In step S2, silicon powder is introduced into fluidized bed 2. High-temperature hydrogen and silicon tetrachloride react with the silicon powder. 23%-35% of the silicon tetrachloride reacts to generate trichlorosilane. The trichlorosilane, unreacted silicon tetrachloride and hydrogen are then mixed at high temperature and fed into the material cooling circuit.

[0111] like Figure 2 As shown, the material cooling process in step S3 includes the following steps:

[0112] S31. The high-temperature mixture at the top of the fluidized bed 2 is fed into the tube flow channel of the four-stage heat recovery unit 6 to perform the first heat exchange and cooling of the high-temperature mixture, reducing the temperature of the high-temperature mixture from 550℃ to 370-490℃.

[0113] S32. The high-temperature mixture after the first heat exchange and cooling is sent into the tube flow channel of the three-stage heat recovery unit 5 to perform a second heat exchange and cooling, reducing the temperature of the high-temperature mixture from 370-490℃ to 300-320℃.

[0114] S33. The high-temperature mixture after the second heat exchange and cooling is sequentially fed into the cyclone separator 10 and the filter 11 to remove silicon powder;

[0115] S34. The high-temperature mixture after removing silicon powder is sent into the tube flow channel of the secondary heat recovery unit 4 to perform a third heat exchange and cooling of the high-temperature mixture, reducing the temperature of the high-temperature mixture from 300-320℃ to 220-240℃.

[0116] S35. The high-temperature mixture after the third heat exchange and cooling is sequentially fed into washing tower I12 and washing tower II13 for washing and cooling, so that the temperature of the mixture is reduced from 220-240℃ to 130-150℃.

[0117] S36. The washed and cooled mixture is sent to the tube flow channel of the first-stage heat recovery unit 3 for the fourth heat exchange and cooling, reducing the temperature of the mixture from 130-150℃ to 80-100℃, and finally sent to the downstream unit.

[0118] like Figure 2 As shown, step S4, the shutdown and cooling process, includes the following steps:

[0119] S41. Open the bypass valve I16 of the three-stage heat recovery unit 5 so that most of the low-temperature material in the material heating line does not enter the shell-side flow channel of the three-stage heat recovery unit 5, but directly enters the shell-side flow channel of the subsequent four-stage heat recovery unit 6 through valve I16, thereby bypassing the three-stage heat recovery unit 5 to cool it down, and controlling the cooling rate of the bottom of the fluidized bed 2 to be 40-60℃ / h.

[0120] S42. When the cooling rate at the bottom of fluidized bed 2 is lower than 40℃ / h, open the bypass valve II17 of the secondary heat recovery unit 4 so that most of the low-temperature material in the material heating line does not enter the shell-side flow channel of the secondary heat recovery unit 4, but directly enters the fluidized bed 2 through valve II17 to cool the fluidized bed 2.

[0121] S43. When the cooling rate at the bottom of fluidized bed 2 is lower than 40℃ / h, close valve Ⅲ18 on the hydrogen delivery pipeline that controls the hydrogen entering the material heating line, and open valve Ⅳ19 that controls the hydrogen entering the first heat exchanger 14 (circulating water heat exchanger), so that the hydrogen in the hydrogen delivery pipeline enters the tube flow channel of the first heat exchanger 14, cools the hydrogen and directly introduces it into fluidized bed 2 to continue cooling the inside of fluidized bed 2;

[0122] S44. When the cooling rate at the bottom of fluidized bed 2 is lower than 40℃ / h, close valve IV19 and open valve V20, which controls the hydrogen to enter the second heat exchanger 15 (7℃ heat exchanger), so that the hydrogen in the hydrogen delivery pipeline enters the tube flow channel of the second heat exchanger 15, cools the hydrogen and then directly introduces it into fluidized bed 2 to continue cooling the inside of fluidized bed 2 until the system cooling is completed.

[0123] The above-mentioned stepped cooling method results in uniform and faster cooling, effectively saving downtime for maintenance and reducing costs.

[0124] In the above steps, the cooling material introduced in step S41 is the material that has not been heated by heat exchange in the three-stage heat recovery unit 5; the cooling material introduced in step S42 is the material that has not been heated by heat exchange in the two-stage heat recovery unit 4, the three-stage heat recovery unit 5, and the four-stage heat recovery unit 6, and its temperature is lower than that of the material introduced in step S41; the cooling material introduced in step S43 is hydrogen gas that has been cooled by the circulating water heat exchanger, and its temperature is lower than that of the material introduced in step S42; the cooling material introduced in step S44 is hydrogen gas that has been cooled by the 7°C heat exchanger, and its temperature is lower than that of the hydrogen gas introduced in step S43.

[0125] In this invention, during the initial cooling phase, the fluidized bed 2 temperature is approximately 560°C. Due to this high temperature, lower-temperature materials need to be heated to a temperature difference of approximately 100°C with the fluidized bed 2 by passing through a primary heat recovery unit 3, a vaporizer 7, a superheater 8, a secondary heat recovery unit 4, a quaternary heat recovery unit 6, and an electric heater 9. This process then cools the fluidized bed 2, preventing direct cooling of the high-temperature fluidized bed 2 by the low-temperature materials, which could damage the equipment. If cold materials are used directly for cooling during the initial cooling phase (approximately 560°C), the cooling rate will exceed 60°C / h, potentially damaging other heat exchangers.

[0126] Mid-stage cooling: When the temperature of fluidized bed 2 is low, resulting in a small temperature difference between the fluidized bed 2 and the material being cooled, and the cooling rate is below 40℃ / h, the material with the lower temperature does not need to be preheated. It directly bypasses the secondary heat recovery unit 4, the tertiary heat recovery unit 5, the quaternary heat recovery unit 6, and the electric heater 9, and enters the fluidized bed 2 through valve II 17 to cool it down, ensuring stable cooling.

[0127] In the later stage of cooling: when the temperature of fluidized bed 2 is below 250℃, the cooling rate of the cold material directly bypassing the secondary heat recovery unit 4, tertiary heat recovery unit 5, quaternary heat recovery unit 6, and electric heater 9 cannot meet the cooling rate of 40℃ / h at the bottom of fluidized bed 2. Therefore, it is necessary to sequentially activate the circulating water heat exchanger and then the 7℃ heat exchanger (the cooling material no longer passes through the material heating line). After cooling the cold material through the circulating water heat exchanger and the 7℃ heat exchanger, the fluidized bed 2 is cooled again until the temperature of fluidized bed 2 drops below 50℃, completing the entire cooling process.

[0128] By sequentially introducing cooling materials at lower temperatures, it is ensured that the cold materials and fluidized bed 2 maintain a sufficient temperature difference in the early, middle, and late stages of cooling, and the cooling rate can be maintained at 40-60℃ / h, which shortens the cooling time and ensures the safe and stable operation of the equipment.

[0129] The embodiments of the present invention have been described in detail above, but the present invention is not limited to the described embodiments. Those skilled in the art can make various equivalent modifications or substitutions without departing from the spirit of the present invention, and these equivalents or substitutions are all included within the scope defined by the claims of the present invention.

Claims

1. A method for heating and cooling polycrystalline silicon cold hydrogenation, characterized in that, Includes the following steps: S1. Mix hydrogen and silicon tetrachloride, and then send the mixture into the material heating line. Use a vaporizer and a multi-stage heat recovery unit to vaporize the mixture and perform step heat exchange to raise the temperature. Then send the mixture into a fluidized bed. S2. In the fluidized bed, high-temperature hydrogen, silicon tetrachloride and silicon powder react to generate trichlorosilane, and the high-temperature mixture of trichlorosilane, unreacted silicon tetrachloride and hydrogen in the fluidized bed is sent into the material cooling line. S3, the material cooling line performs stepped heat exchange cooling, silicon powder filtration and washing on the high-temperature mixture, and sends the finally stepped heat exchanged and cooled material to the downstream unit. S4. When the cold hydrogenation heating and cooling process needs to be stopped for maintenance after a period of time, a stepped cooling method is adopted in combination with the material heating line. Low-temperature hydrogen and low-temperature materials in the material heating line are used to cool the fluidized bed during shutdown. The stepped cooling method involves sequentially introducing cooling materials with lower temperatures to ensure that the cooling materials and the fluidized bed maintain a sufficient temperature difference in the early, middle and late stages of cooling, and the cooling rate is stable.

2. The cold hydrogenation heating and cooling method as described in claim 1, characterized in that, Step S1 includes the following steps: S11. The hydrogen and silicon tetrachloride transported by the hydrogen pipeline and silicon tetrachloride pipeline are fed into the mixer for mixing. S12. The mixture after mixing in the mixer is sent into the shell-side flow channel of the primary heat recovery unit to perform the first heat exchange and temperature rise of the mixture from T1 to T2. S13. The mixture after the first heat exchange and heating is sequentially fed into the vaporizer and superheater for vaporization and heating, raising the temperature of the mixture from T2 to T3. S14. The vaporized and heated mixture is fed into the shell-side flow channel of the secondary heat recovery unit to perform a second heat exchange and temperature increase on the mixture, raising the temperature of the mixture from T3 to T4. S15. The mixture after the second heat exchange and heating is sent into the shell-side flow channel of the three-stage heat recovery unit to perform a third heat exchange and heating, raising the temperature of the mixture from T4 to T5. S16. The mixture after the third heat exchange and heating is sent into the shell-side flow channel of the fourth-stage heat recovery unit to perform the fourth heat exchange and heating of the mixture, raising the temperature of the mixture from T5 to T6. S17. The mixture after the fourth heat exchange and heating is sent to the electric heater to electrically heat the mixture, raising its temperature from T6 to T7, and then sent to the bottom of the fluidized bed.

3. The cold hydrogenation heating and cooling method as described in claim 2, characterized in that, In step S2, silicon powder is introduced into the fluidized bed. High-temperature hydrogen and silicon tetrachloride react with the silicon powder, and 23%-35% of the silicon tetrachloride reacts to generate trichlorosilane. The trichlorosilane, unreacted silicon tetrachloride, and hydrogen are then mixed at high temperature and fed into the material cooling circuit.

4. The cold hydrogenation heating and cooling method as described in claim 2, characterized in that, Step S3 includes the following steps: S31. The high-temperature mixture at the top of the fluidized bed is fed into the tube flow channel of the four-stage heat recovery unit to perform the first heat exchange and cooling of the high-temperature mixture, reducing the temperature of the high-temperature mixture from M1 to M2. S32. The high-temperature mixture after the first heat exchange and cooling is sent into the tube flow channel of the three-stage heat recovery unit to perform a second heat exchange and cooling, reducing the temperature of the high-temperature mixture from M2 to M3. S33. The high-temperature mixture after the second heat exchange and cooling is sequentially fed into a cyclone separator and a filter to remove silicon powder; S34. The high-temperature mixture after removing silicon powder is sent into the tube flow channel of the secondary heat recovery unit to perform a third heat exchange and cooling of the high-temperature mixture, reducing the temperature of the high-temperature mixture from M3 to M4. S35. The high-temperature mixture after the third heat exchange and cooling is sequentially fed into washing tower I and washing tower II for washing and cooling, and the temperature of the mixture is reduced from M4 to M5. S36. The washed and cooled mixture is sent to the tube side of the primary heat recovery unit for the fourth heat exchange and cooling, reducing the temperature of the mixture from M5 to M6, and finally sent to the downstream unit.

5. The cold hydrogenation heating and cooling method as described in claim 4, characterized in that, In the material heating circuit of step S1, T1 is 50-60℃, T2 is 100-120℃, T3 is 150-170℃, T4 is 220-240℃, T5 is 310-330℃, T6 is 470-490℃, and T7 is 560℃. In the material cooling circuit of step S3, M1 is 550℃, M2 is 370-490℃, M3 is 300-320℃, M4 is 220-240℃, M5 is 130-150℃, and M6 is 80-100℃.

6. The cold hydrogenation heating and cooling method as described in claim 1, characterized in that, Step S4 includes the following steps: S41. Open the bypass valve I of the three-stage heat recovery unit so that most of the low-temperature material in the material heating line does not enter the shell-side flow channel of the three-stage heat recovery unit, but directly enters the shell-side flow channel of the subsequent four-stage heat recovery unit through valve I, thereby bypassing the three-stage heat recovery unit to cool it down, and controlling the cooling rate of the bottom of the fluidized bed to N1. S42. When the cooling rate at the bottom of the fluidized bed is lower than that of N2, open the bypass valve II of the secondary heat recovery unit so that most of the low-temperature material in the material heating line does not enter the shell-side flow channel of the secondary heat recovery unit, but directly enters the fluidized bed through valve II to cool the fluidized bed. S43. When the cooling rate at the bottom of the fluidized bed is lower than N3, close valve III on the hydrogen delivery pipeline that controls the hydrogen entering the material heating line, and open valve IV that controls the hydrogen entering the first heat exchanger, so that the hydrogen in the hydrogen delivery pipeline enters the tube flow channel of the first heat exchanger, cools the hydrogen and then directly introduces it into the fluidized bed to continue cooling the inside of the fluidized bed. S44. When the cooling rate at the bottom of the fluidized bed is lower than N4, close valve IV and open valve V, which controls the entry of hydrogen into the second heat exchanger, so that the hydrogen in the hydrogen delivery pipeline enters the tube-side flow channel of the second heat exchanger, cools the hydrogen, and then directly introduces it into the fluidized bed to continue cooling the inside of the fluidized bed until the system cooling is complete; wherein, the heat exchange temperature of the first heat exchanger is greater than the heat exchange temperature of the second heat exchanger.

7. The cold hydrogenation heating and cooling method as described in claim 6, characterized in that, In step S4, N1 is 40-60℃ / h, N2 is 40℃ / h, N3 is 40℃ / h, and N4 is 40℃ / h; the first heat exchanger is a circulating water heat exchanger, and the second heat exchanger is a 7℃ heat exchanger.

8. A polycrystalline silicon cold hydrogenation heating and cooling system based on the cold hydrogenation heating and cooling method according to any one of claims 1-7, characterized in that, This includes mixers, heat recovery units, fluidized beds, scrubbing tower units, vaporization superheating units, silicon powder filtration units, and shutdown cooling units; The mixer is connected to a hydrogen delivery pipeline and a silicon tetrachloride delivery pipeline at its inlet. The heat recovery assembly includes several stages of heat recovery units connected in sequence. Each stage of heat recovery unit is equipped with a shell-side flow channel and a tube-side flow channel for heat exchange. The shell-side flow channels of the several stages of heat recovery units form a material heating line, and the tube-side flow channels form a material cooling line. In the material heating circuit, the shell-side flow channel inlet of the first-stage heat recovery unit is connected to the outlet of the mixer, the shell-side flow channel outlet of the previous-stage heat recovery unit is connected to the shell-side flow channel inlet of the next-stage heat recovery unit, and the shell-side flow channel outlet of the last-stage heat recovery unit is connected to the bottom inlet of the fluidized bed. In the material cooling circuit, the tube-side flow channel inlet of the final stage heat recovery unit is connected to the top outlet of the fluidized bed, the tube-side flow channel outlet of the next stage heat recovery unit is connected to the tube-side flow channel inlet of the previous stage heat recovery unit, and the tube-side flow channel outlet of the second stage heat recovery unit is connected to the inlet of the washing tower assembly, which includes several washing towers connected in sequence. The vaporization superheating assembly is installed in the material heating line, the silicon powder filtration assembly is installed in the material cooling line, and one end of the shutdown cooling assembly is connected to the hydrogen conveying pipeline, and the other end is connected to the material heating line and the bottom inlet of the fluidized bed.

9. The cold hydrogenation heating and cooling system as described in claim 8, characterized in that, The heat recovery system includes a primary heat recovery unit, a secondary heat recovery unit, a tertiary heat recovery unit, and a quaternary heat recovery unit. The shell-side flow channel inlet of the first-stage heat recovery unit is connected to the outlet of the mixer; the shell-side flow channel outlet of the first-stage heat recovery unit is connected to the shell-side flow channel inlet of the second-stage heat recovery unit; the shell-side flow channel outlet of the second-stage heat recovery unit is connected to the shell-side flow channel inlet of the third-stage heat recovery unit; the shell-side flow channel outlet of the third-stage heat recovery unit is connected to the shell-side flow channel inlet of the fourth-stage heat recovery unit; and the shell-side flow channel outlet of the fourth-stage heat recovery unit is connected to the bottom inlet of the fluidized bed. The fluidized bed top outlet is connected to the tube-side flow channel inlet of the fourth-stage heat recovery unit, the tube-side flow channel outlet of the fourth-stage heat recovery unit is connected to the tube-side flow channel inlet of the third-stage heat recovery unit, the tube-side flow channel outlet of the third-stage heat recovery unit is connected to the tube-side flow channel inlet of the second-stage heat recovery unit, and the tube-side flow channel outlet of the second-stage heat recovery unit is connected to the combined inlet of the scrubbing tower. The vaporization superheating assembly is set in the material heating line between the shell-side flow channel outlet of the primary heat recovery unit and the shell-side flow channel inlet of the secondary heat recovery unit, and includes a vaporizer and a superheater. The vaporizer inlet is connected to the shell-side flow channel outlet of the first-stage heat recovery unit, the vaporizer outlet is connected to the superheater inlet, and the superheater outlet is connected to the shell-side flow channel inlet of the second-stage heat recovery unit. It also includes an electric heater, wherein the shell-side flow channel outlet of the four-stage heat recovery unit is connected to the inlet of the electric heater, and the outlet of the electric heater is connected to the bottom inlet of the fluidized bed; The silicon powder filter assembly is installed in the material cooling line between the outlet of the tube-side flow channel of the tertiary heat recovery unit and the inlet of the tube-side flow channel of the secondary heat recovery unit, and includes a cyclone separator and a filter. The cyclone separator inlet is connected to the outlet of the tube-side flow channel of the third-stage heat recovery unit, the cyclone separator outlet is connected to the filter inlet, and the filter outlet is connected to the inlet of the tube-side flow channel of the second-stage heat recovery unit. The washing tower assembly includes washing tower I and washing tower II. The bottom inlet of washing tower I is connected to the tube-side flow channel outlet of the secondary heat recovery unit, the top outlet of washing tower I is connected to the bottom inlet of washing tower II, the top outlet of washing tower II is connected to the tube-side flow channel inlet of the primary heat recovery unit, and the tube-side flow channel outlet of the primary heat recovery unit is connected to the downstream device.

10. The cold hydrogenation heating and cooling system as described in claim 9, characterized in that, The shutdown cooling assembly includes a first heat exchanger and a second heat exchanger connected in parallel. The heat exchange temperature of the first heat exchanger is greater than that of the second heat exchanger. The inlet pipes of the first heat exchanger and the second heat exchanger are connected to the hydrogen delivery pipeline, and the outlet pipes are connected to the bottom inlet of the fluidized bed. A first pipe connecting the inlet and outlet is provided between the shell-side flow channel inlet and outlet of the three-stage heat recovery unit, and valve I is provided on the first pipe; The outlet main pipes of the first heat exchanger and the second heat exchanger are connected to a second pipe, which is connected to the inlet of the shell-side flow channel of the secondary heat recovery unit. Valve II is installed on the second pipe. The hydrogen delivery pipeline is equipped with valve III for controlling the entry of materials into the mixer; Valves IV and V are respectively installed on the inlet branch pipes of the first heat exchanger and the second heat exchanger; The first heat exchanger is a circulating water heat exchanger, and the second heat exchanger is a 7°C heat exchanger.

Images