A system and method for propane dehydrogenation to propylene

Abstract

This invention provides a system and method for propane dehydrogenation to propylene, belonging to the field of propane dehydrogenation technology. It solves the problems of increased investment costs, high overall energy consumption, and increased production and operating costs caused by the complex structure of existing technologies. It includes a reaction regeneration system connected to a separation system for processing the reaction gas. The separation system includes a water washing tower, with a compressor suction tank connected to the top of the water washing tower. A reaction gas compressor is connected to the top of the compressor suction tank, a cold box is connected to the cold box, an ethane tower is connected to the cold box, a propylene tower is connected to the bottom of the ethane tower, and a propane tower is connected to the bottom of the propylene tower. The water washing tower washes and cools the reaction gas, preventing catalyst fines from clogging subsequent pipelines and reducing the workload of the cold box. The reaction gas is then separated through the ethane, propylene, and propane towers. This method features low overall energy consumption, a simple structure, high utilization rate of separated byproducts, low investment costs, and low production costs.

Description

Technical Field

[0001] This invention belongs to the field of propane dehydrogenation technology, specifically to a system and method for propane dehydrogenation to propylene. Background Technology

[0002] Propylene is one of the world's most produced basic organic chemical raw materials, second only to ethylene in terms of consumption. Propylene is the raw material for polypropylene plastics, which are commonly used in the automotive and textile industries. It is frequently used in packaging plastic films and many other products. In addition to producing polypropylene, it is also used to produce derivatives such as acrylonitrile, butanol, and octanol. With the rapid growth in demand for downstream products, the demand for propylene has also been increasing year by year. Propane dehydrogenation to propylene technology is one of the main technical routes for industrial propylene production in recent years.

[0003] Propane dehydrogenation is an important process step in the production of propylene and is crucial for the petrochemical industry. Since the discovery of propane dehydrogenation technology in the early 1990s, the industrial propane dehydrogenation technology has become increasingly mature, with fixed bed, moving bed and fluidized bed processes. Currently, all three propane dehydrogenation technologies have been industrialized.

[0004] In recent years, propane dehydrogenation technology has developed rapidly, and the scale of industrial plants has gradually expanded. Currently, the main propane dehydrogenation technologies that have been industrialized and occupy the mainstream market are the Catofin fixed-bed process and the Oleflex moving-bed process. They each have their advantages and are undergoing continuous technological improvements. For example, the Catofin process now uses the lower bulk density dehydrogenation catalyst Catofin 311 and is used in conjunction with HGM (heat-generating material), which further improves selectivity. The Oleflex process, while ensuring that the catalyst performance remains unchanged, further reduces the platinum content in the catalyst and improves the catalyst's resistance to carbon deposition, enabling the dehydrogenation reaction to maintain operation for a longer period of time.

[0005] China's propane dehydrogenation technology has made rapid progress in both catalyst and complete process development. In recent years, it has entered the industrialization stage. Chinese research teams are further accelerating the development of propane dehydrogenation technology, continuously improving the technical level and enhancing technical competitiveness. China's propane dehydrogenation technology has achieved the development of catalysts and complete processes.

[0006] In the near future, with the increasing trend towards lighter raw materials, the diversification of propylene feedstocks will become a development trend in the industry. Compared with technologies such as steam cracking and catalytic cracking for producing propylene, propane dehydrogenation technology, due to its single feedstock and easy product separation, can significantly improve propylene yield, with a total propylene yield exceeding 80%. The production cost of propane dehydrogenation is closely related only to the fluctuation of propane prices, which are directly linked to naphtha prices and the propylene market. Propane dehydrogenation technology can convert low-value propane into high-value propylene, thereby improving efficiency. However, existing propane dehydrogenation systems for producing propylene have complex structures, leading to increased investment costs. During operation, they also have high overall energy consumption, resulting in correspondingly higher production and operating costs. Summary of the Invention

[0007] To address the aforementioned problems, the present invention aims to provide a system and method for propane dehydrogenation to propylene. This system incorporates a water washing tower to wash and cool the reaction gas, preventing catalyst powder from clogging subsequent pipelines and reducing the workload of the cold box. The reaction gas is then separated using ethane, propylene, and propane towers. The system features low overall energy consumption, a simple structure, high utilization rate of separated byproducts, low investment costs, and low production costs.

[0008] The technical solution adopted in this invention is as follows:

[0009] A propane dehydrogenation to propylene system includes a reaction regeneration system connected to a separation system for processing reaction gases. The separation system includes a water washing tower connected to the reaction regeneration system. The top of the water washing tower is connected to a compressor intake tank via a pipe. The top of the compressor intake tank is connected to a reaction gas compressor. The reaction gas compressor is connected to a cold box. The cold box is connected to an ethane tower. The bottom of the ethane tower is connected to a propylene tower via a pipe. The bottom of the propylene tower is connected to a propane tower via a pipe.

[0010] Preferably, the washing tower is provided with washing circulation pipelines for circulating washing water at the top, middle and bottom. The washing circulation pipelines located in the middle and bottom of the washing tower are connected, and the washing circulation pipeline at the bottom diverts part of the washing water to the washing circulation pipeline in the middle. The washing circulation pipeline in the middle is provided with a catalyst clarification tank and a clarified water tank. The bottom of the catalyst clarification tank is connected to a sedimentation tank.

[0011] Preferably, the compressor suction tank and the reaction gas compressor are provided in two sets and connected in series for two-stage compression, and the bottom of the compressor suction tank is connected to the water washing tower.

[0012] Preferably, the top of the ethane tower is connected to an ethane tower top reflux tank, and the pipe connecting the ethane tower and the ethane tower top reflux tank extends into the cold box. The bottom of the ethane tower top reflux tank is connected to two pipes, one of which is connected to the ethane tower, and the other pipe discharges ethane outward.

[0013] Preferably, the top of the propylene tower is connected to a propylene tower top reflux tank, and the pipe connecting the propylene tower and the propylene tower top reflux tank extends into the cold box. The bottom of the propylene tower top reflux tank is connected to two pipes, one of which is connected to the propylene tower, and the other pipe discharges propylene outward.

[0014] Preferably, the top of the propane tower is connected to a propane tower top reflux tank, and the pipe connecting the propane tower and the propane tower top reflux tank extends into the cold box. The bottom of the propane tower top reflux tank is connected to two pipes, one of which is connected to the propane tower and the other is connected to the feed end of the reaction regeneration system.

[0015] Preferably, the reaction regeneration system includes a feed heat exchanger, a heating furnace, and a reactor connected in sequence. The bottom of the reactor is connected to a regenerator via a pipe, and the bottom of the regenerator is connected to the reactor via a pipe. The top of the reactor is connected to the heat source inlet of the feed heat exchanger via a pipe, and the heat source outlet of the feed heat exchanger is connected to a steam generator via a pipe. The steam generator is connected to a water washing tower via a pipe.

[0016] Preferably, the reactor is equipped with a primary and secondary cyclone separator, a tertiary cyclone separator is installed on the pipe connecting the reactor to the feed heat exchanger, a quaternary cyclone separator is connected to the bottom of the tertiary cyclone separator, the top of the quaternary cyclone separator is connected to the heat source inlet of the feed heat exchanger through a pipe, a reaction fine powder collection tank is connected to the bottom of the quaternary cyclone separator, a waste catalyst tank is connected to the waste catalyst tank, and a loading device is installed below the waste catalyst tank.

[0017] Preferably, the regenerator is equipped with a primary and secondary regeneration cyclone separator, a tertiary regeneration cyclone separator is connected to the top of the regenerator, the top of the tertiary regeneration cyclone separator is connected to a waste heat generating boiler via a pipe and a double-acting slide valve is installed in the pipe, the waste heat generating boiler is connected to a flue gas dust collector, the flue gas dust collector is connected to a chimney, a quaternary regeneration cyclone separator is connected to the bottom of the tertiary regeneration cyclone separator, the top of the quaternary regeneration cyclone separator is connected to the waste heat generating boiler via a pipe, and the bottom of the quaternary regeneration cyclone separator is connected to a regenerated fine powder collection tank, which is connected to a waste catalyst tank.

[0018] A method for producing propylene by propane dehydrogenation includes the following steps:

[0019] S1. Propane is fed into the feed heat exchanger. After being heated in the furnace, the propane enters the reactor and reacts with the catalyst to generate reaction gas. The unprocessed catalyst in the reactor is sent to the regenerator for coking and regeneration to obtain the regenerated catalyst. The regenerated catalyst is then returned to the reactor for continued use. The flue gas generated during the regeneration process passes through the first and second stage regeneration cyclone separators, the third stage regeneration cyclone separator, and the fourth stage regeneration cyclone separator to separate the catalyst fine powder. Finally, the flue gas passes through the waste heat generator to recover heat and the flue gas dust collector to remove dust before being discharged from the chimney.

[0020] S2. The reaction gas passes through the first and second stage cyclone separators, the third stage cyclone separator, and the fourth stage cyclone separator in sequence to separate the catalyst fine powder. It is then fed into the feed heat exchanger as a heat source and then fed into the steam generator for cooling.

[0021] S3. The cooled reaction gas enters the water washing tower for washing. The water washing tower is equipped with three washing circulation pipelines. The washing circulation pipeline located in the middle of the water washing tower uses a catalyst clarification tank to separate the catalyst and transport it to the settling tank for further separation.

[0022] S4. The washed reaction gas enters the compressor intake tank, is then compressed by the reaction gas compressor and sent to the cold box to separate the methane hydrogen and condensate.

[0023] S5. The condensate passes through the ethane tower, propylene tower and propane tower in sequence to separate ethane, propylene and propane. The propane is then fed into the feed end of the feed heat exchanger to react again.

[0024] In summary, due to the adoption of the above technical solution, the beneficial effects of the present invention are:

[0025] A water washing tower is set up to wash and cool the reaction gas, which prevents the catalyst fine powder from clogging the subsequent pipelines and reduces the workload of the cold box. The reaction gas is then separated by ethane tower, propylene tower and propane tower. The overall energy consumption is low, the structure is simple, the utilization rate of the separated by-products is high, the investment cost is low and the production cost is low. Attached Figure Description

[0026] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0027] Figure 1 This is a flowchart provided for an embodiment of the present invention;

[0028] Figure 2This is a schematic diagram of the cold box structure provided in an embodiment of the present invention.

[0029] Figure Descriptions: 1-Reaction Regeneration System; 2-Separation System; 3-Reaction Primary and Secondary Cyclone Separators; 4-Regeneration Primary and Secondary Cyclone Separators; 5-Reaction Tertiary Cyclone Separator; 6-Reaction Quaternary Cyclone Separator; 7-Reaction Fine Powder Collection Tank; 8-Regeneration Tertiary Cyclone Separator; 9-Regeneration Quaternary Cyclone Separator; 10-Regeneration Fine Powder Collection Tank; 11-Internal Heat Extraction Pipe of Reaction; 12-Internal Heat Extraction Pipe of Regeneration; 13-Heating Furnace; 14-Heating Furnace Heat Extraction Pipe; 15-Feed Heat Exchanger; 16-Steam Generator; 17-Waste Heat Steam Generator; 18-Flue Gas Dust Collector; 19-Chimney; 20-Fresh Catalyst Tank; 21-Waste Catalyst Tank; 22-Small Additive Dosing Device; 23-Loader; 24-Main Fan; 25-Auxiliary Combustion Chamber; 26-Double-Action Slide Valve; 27-Regenerator; 28- Reactor; 201-Water washing tower; 202-Top circulation pump; 203-Bottom circulation pump; 204-Catalyst clarification tank; 205-Clarified water tank; 206-Catalyst transfer pump; 207-Middle circulation pump; 208-Settling tank; 209-Compressor suction tank; 210-Reaction gas compressor; 211-Cold box; 212-Ethane tower; 213-Ethane tower top reflux tank; 214-Ethane tower top reflux pump; 215-Ethane tower bottom pump; 216-Propylene tower; 217-Propylene tower top reflux tank; 218-Propylene tower top reflux pump; 219-Propylene tower bottom pump; 220-Propane tower; 221-Propane tower top reflux tank; 222-Propane tower top reflux pump; 223-Depropane tower bottom pump; 224-Separation tank; 225-First stage compression pipe; 226-Second stage compression pipe. Detailed Implementation

[0030] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0031] Therefore, the following detailed description of the embodiments of the invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the invention without inventive effort are within the scope of protection of the invention.

[0032] In the description of this invention, it should be noted that if terms such as "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," or "outer" are used to indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship commonly used when the product is in use, they are only for the convenience of describing this invention and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this invention.

[0033] The following is combined with Figures 1-2 The present invention will be described in detail below.

[0034] Example

[0035] A system for propane dehydrogenation to propylene, such as Figure 1 As shown, the system includes a reaction regeneration system 1, which is connected to a separation system 2 for processing reaction gases. The separation system 2 includes a water washing tower 201 connected to the reaction regeneration system 1. The top of the water washing tower 201 is connected to a compressor suction tank 209 via a pipe. The top of the compressor suction tank 209 is connected to a reaction gas compressor 210. The reaction gas compressor 210 is connected to a cold box 211. The cold box 211 is connected to an ethane tower 212. The bottom of the ethane tower 212 is connected to a propylene tower 216 via a pipe. The bottom of the propylene tower 216 is connected to a propane tower 220 via a pipe. An ethane tower bottom pump 215 is installed in the pipe connecting the ethane tower 212 and the propylene tower 216, and a propylene tower bottom pump 219 is installed in the pipe connecting the propylene tower 216 and the propane tower 220.

[0036] like Figure 1 As shown, the washing tower 201 is equipped with washing circulation pipelines at its top, middle, and bottom for circulating washing water. The washing circulation pipelines located at the middle and bottom of the washing tower 201 are connected, and the bottom washing circulation pipeline diverts part of the washing water to the middle washing circulation pipeline. The middle washing circulation pipeline is equipped with a catalyst clarification tank 204 and a clarified water tank 205. The bottom of the catalyst clarification tank 204 is connected to a settling tank 208. The three washing circulation pipelines of the washing tower 201 are respectively equipped with a top circulation pump 202, a middle circulation pump 207, and a bottom circulation pump 203. The outlet of the bottom circulation pump 203 is connected to the middle washing circulation pipeline, thereby sending the washing water containing catalyst fine powder at the bottom to the catalyst clarification tank 204 for separation. The separated catalyst is transported by the catalyst transfer pump 206 to the settling tank 208 for further separation. The clarified water in the catalyst clarification tank 204 is collected in the clarified water tank 205 and transported by the middle circulation pump 207. The three-stage cycle washing system ensures a noticeable washing effect.

[0037] The compressor suction tank 209 and the reaction gas compressor 210 are configured as two sets connected in series for two-stage compression, ensuring the compression ratio while preventing damage to the reaction gas compressor 210. For example... Figure 2 As shown, the first-stage reaction gas compressor 210 first compresses the reaction gas in the compressor suction tank 209 and extends it into the cold box 211 through a compression pipe 225 for cooling. The condensate and reaction gas enter the second-stage compressor suction tank 209, where the second-stage reaction gas compressor 210 further compresses the reaction gas and transports it through a second compression pipe 226 to the separation tank 224 located in the cold box 221 for separation, separating methane hydrogen and condensate. The methane hydrogen can be used as fuel for the heating furnace, reducing fuel consumption, while the condensate undergoes subsequent separation operations. The bottom of the compressor suction tank 209 is connected to the water washing tower 201, allowing the collected condensate to be returned to the water washing tower 201 for reuse and also reducing the temperature of the washing water.

[0038] The top of ethane tower 212 is connected to an ethane tower top reflux tank 213, and the pipe connecting ethane tower 212 and ethane tower top reflux tank 213 extends into a cold box 211. The bottom of ethane tower top reflux tank 213 is connected to two pipes, one of which connects to ethane tower 212, and the other discharges ethane. Ethanol tower 212 performs gas-liquid two-phase separation on the condensate. The gas is discharged from the top of ethane tower 212 and condensed in the cold box 211 to form a liquid phase, which eventually collects in the ethane tower top reflux tank 213. Then, ethane is pumped to the outside and ethane tower 212 by ethane tower top reflux pump 214. Part of the ethane is sent to the outside for direct recovery, and the other part is returned to the top of ethane tower 212 for reflux. The liquid phase at the bottom of ethane tower 212 is pumped to propylene tower 216 by ethane tower bottom pump 215. Ethane tower 212 has a simple structure, low investment cost, high by-product utilization rate, and low production cost.

[0039] The top of propylene tower 216 is connected to a propylene tower top reflux tank 217, and the pipe connecting propylene tower 216 and propylene tower top reflux tank 217 extends into a cold box 211. The bottom of propylene tower top reflux tank 217 is connected to two pipes, one of which connects to propylene tower 216, and the other discharges propylene. Propylene tower 216 performs gas-liquid two-phase separation on the bottom liquid of ethane tower 212. The gas exits from the top of propylene tower 216 and, after condensation in the cold box 211, forms a liquid phase, which eventually collects in the propylene tower top reflux tank 217. Propylene is then pumped to the outside and to propylene tower 216 by propylene tower top reflux pump 218. Part of the propylene is sent to the outside for direct recovery, while the other part is returned to the top of propylene tower 216 for reflux. The bottom liquid phase of propylene tower 216 is pumped to propane tower 220 by propylene tower bottom pump 219. Propylene tower 216 has a simple structure, low investment cost, high by-product utilization rate, and low production cost.

[0040] The top of propane tower 220 is connected to a propane tower top reflux tank 221, and the pipe connecting propane tower 220 and propane tower top reflux tank 221 extends into cold box 211. The bottom of propane tower top reflux tank 221 is connected to two pipes, one of which is connected to propane tower 220, and the other is connected to the feed end of reaction regeneration system 1. Propane tower 220 performs gas-liquid two-phase separation on the bottom liquid of propylene tower 216. The gas is discharged from the top of propane tower 220 and condensed in cold box 211 to form a liquid phase, which is finally collected in propane tower top reflux tank 221. Then, propane is pumped by propane tower top reflux pump 222 to reaction regeneration system 1 and propane tower 220. Part of the propane is sent to reaction regeneration system 1 to continue to participate in the reaction, and the other part of the propane is returned to the top of propane tower 220 for reflux. The bottom liquid phase of propylene tower 216 is sent to the outside as a heavy phase by depropane tower bottom pump 223. The propane tower 220 has a simple structure, low investment cost, high by-product utilization rate, and low production cost.

[0041] like Figure 2 As shown, cold box 211 uses three propylene streams as refrigerants: propylene one (5-15℃), propylene two (-25--7℃), and propylene three (-50--30℃). Two of these streams can also be used in combination. Cold box 211 can also cool the circulating water at the top of the water washing tower. Cold box 211 has high utilization rate, significant heat exchange effect, simple structure, low energy consumption, and low production cost. Propylene one, propylene two, and propylene three are compressed in three stages by a propylene refrigeration compressor. The inlet temperature of the first stage is 5-15℃, and the pressure is 0.5-0.8 MPa; the inlet temperature of the second stage is -25--7℃, and the pressure is 0.15-0.4 MPa; the inlet temperature of the third stage is -50--30℃, and the pressure is 0.03-0.2 MPa. The outlet of the propylene refrigeration compressor can be used as a heat source for the reboilers of each tower, or the superheated steam produced in the unit can be matched with the outlet of the propylene refrigeration compressor to serve as the reboilers for each tower, adjusted according to the required process conditions of the tower.

[0042] The reaction regeneration system 1 includes a feed heat exchanger 15, a heater 13, and a reactor 28 connected in sequence. A regenerator 27 is connected to the bottom of reactor 28 via a pipe, and the bottom of regenerator 27 is connected to reactor 28 via a pipe. The top of reactor 28 is connected to the heat source inlet of feed heat exchanger 15 via a pipe, and the heat source outlet of feed heat exchanger 15 is connected to steam generator 16 via a pipe. Steam generator 16 is connected to water scrubbing tower 201 via a pipe. Propane enters feed heat exchanger 15 for initial heating, where the heat source is the reaction gas. Steam generator 16 is used to further cool the reaction gas, reducing the temperature of the reaction gas and thus reducing the load on heater 13 and water scrubbing tower 201, thereby lowering production costs. Heater 13 is also equipped with a heater heat exchanger pipe 14, utilizing the waste heat from the exhaust gas to produce steam, comprehensively utilizing thermal energy and reducing the temperature of the exhaust gas. Regenerator 27 recycles and regenerates the catalyst in reactor 28 to ensure the normal and continuous operation of reactor 28.

[0043] Reactor 28 is equipped with 4 to 8 sets of internal heat exchange pipes 11 in the dilute phase section. This generates steam while lowering the dilute phase temperature, reducing side reactions and increasing reaction yield. Regenerator 27 is equipped with 6 to 12 sets of internal heat exchange pipes 12 in the dense phase section. This design is simple in structure, has low investment costs, lowers the dense phase temperature, and generates saturated steam, thus reducing production costs. The number of internal heat exchange pipes 11 and internal heat exchange pipes 12 can be adjusted according to the production scale of the unit.

[0044] The regenerator 27 is also connected to a fresh catalyst tank 20. During startup, the fresh catalyst tank 20 adds catalyst to the regenerator 27 and then transfers it to the reactor 28, saving startup time and effectively increasing catalyst temperature. During normal production, fresh catalyst is added to the regenerator 27 via a small additive dispenser 22. The regenerator 27 is also connected to an auxiliary combustion chamber 25, which supplies coke to the regenerator 27 via a main fan 24.

[0045] Reactor 28 is equipped with a primary and secondary cyclone separator 3. A tertiary cyclone separator 5 is installed on the pipe connecting reactor 28 and feed heat exchanger 15. A quaternary cyclone separator 6 is connected to the bottom of the tertiary cyclone separator 5. The top of the quaternary cyclone separator 6 is connected to the heat source inlet of feed heat exchanger 15 via a pipe. A fine catalyst collection tank 7 is connected to the bottom of the quaternary cyclone separator 6. A waste catalyst tank 21 is connected to the waste catalyst tank 21. A loading device 23 is installed below the waste catalyst tank 21. The primary and secondary cyclone separators 3 separate the catalyst fine powder carried by the reaction gas and allow it to fall into reactor 28 for easy recycling. The tertiary and quaternary cyclone separators 5 and 6 further separate the reaction gas discharged from reactor 28, further reducing the amount of catalyst fine powder carried. The reaction gas discharged from the tertiary and quaternary cyclone separators 5 and 6 flows together into feed heat exchanger 15, improving product yield. The collected catalyst fine powder is gathered into the reaction fine powder collection tank 7, and then finally transported to the waste catalyst tank 21. The catalyst fine powder is then loaded into the transport vehicle through the loading device 23 for convenient transportation.

[0046] The regenerator 27 is equipped with a primary and secondary regeneration cyclone separator 4. The top of the regenerator 27 is connected to a tertiary regeneration cyclone separator 8. The top of the tertiary regeneration cyclone separator 8 is connected to a waste heat generating boiler 17 via a pipe, and a double-acting slide valve 26 is installed in the pipe. The waste heat generating boiler 17 is connected to a flue gas dust collector 18, and the flue gas dust collector 18 is connected to a chimney 19. The bottom of the tertiary regeneration cyclone separator 8 is connected to a quaternary regeneration cyclone separator 9. The top of the quaternary regeneration cyclone separator 9 is connected to the waste heat generating boiler 17 via a pipe, and the bottom of the quaternary regeneration cyclone separator 9 is connected to a regeneration fine powder collection tank 10. The regeneration fine powder collection tank 10 is connected to a waste catalyst tank 21. The catalyst fines in the flue gas are separated by the first and second stage regeneration cyclone separators 4 and fall into the regenerator 27 for easy recycling. The third and fourth stage regeneration cyclone separators 8 and 9 further separate the flue gas discharged from the regenerator 27. The flue gas discharged from the third stage regeneration cyclone separator 8 passes through the double-acting slide valve 26 and merges with the flue gas discharged from the fourth stage regeneration cyclone separator 9 into the waste heat steam generator 17. The waste heat steam generator 17 uses the heat of the flue gas to generate steam and superheats the saturated steam produced in other locations, resulting in low overall energy consumption and low production costs. The flue gas is then filtered by the flue gas dust collector 18 to remove the final catalyst fines before being discharged from the chimney 19, which is environmentally friendly.

[0047] The primary and secondary cyclone separators 3 are equipped with 8 to 20 sets, and the primary and secondary cyclone separators 4 are equipped with 6 to 16 sets; both the regenerator 27 and the reactor 28 are equipped with stripping sections at the bottom, and the stripping sections can be set with 2 to 5 sections. The number of cyclone separators and the number of stripping sections can be adjusted according to the production scale of the unit.

[0048] A method for producing propylene by propane dehydrogenation includes the following steps:

[0049] S1. Propane is fed into the feed heat exchanger 15. After being heated by the heater 13, the propane enters the reactor 28 and reacts with the catalyst to generate reaction gas. The unprocessed catalyst in the reactor 28 is sent to the regenerator 27 for coke burn-off regeneration to obtain regenerated catalyst. The regenerated catalyst is then returned to the reactor 28 for continued use. The flue gas generated during the regeneration process in the regenerator 27 passes sequentially through the primary and secondary cyclone separators 4, the tertiary cyclone separator 8, and the quaternary cyclone separator 9 to separate fine catalyst powder. Finally, the flue gas passes through the waste heat generator 17 to recover heat and... The dust collector 18 removes dust and discharges it from the chimney 19; the heating furnace 13 heats the propane to 500-600℃, the reaction temperature in the reactor 28 is 550-650℃, the pressure is 0.03-0.1 MPa, and the catalyst-to-propane ratio is 1-20. The preferred reaction temperature is 560-610℃, the pressure is 0.03-0.05 MPa, and the catalyst-to-propane ratio is 7-16; the preferred reaction conditions for the regenerator 27 are: temperature 600-690℃, pressure 0.025-0.045 MPa.

[0050] S2. The reaction gas passes through the first and second stage cyclone separators 3, the third stage cyclone separator 5 and the fourth stage cyclone separator 6 in sequence to separate the catalyst fine powder. It is then fed into the feed heat exchanger 15 as a heat source and then fed into the steam generator 16 for cooling.

[0051] S3. The cooled reaction gas enters the water washing tower 201 for washing. The water washing tower 201 is equipped with three washing circulation pipelines. The washing circulation pipeline located in the middle of the water washing tower 201 uses the catalyst clarification tank 204 to separate the catalyst and transport it to the settling tank 208 for further separation. The top pressure of the water washing tower 201 is 0.02~0.04 MPa.

[0052] S4. The washed reaction gas enters the compressor intake tank 209, and is then compressed by the reaction gas compressor 210 and transported to the cold box 211 to separate the methane hydrogen and condensate; the reaction gas compressor 210 compresses the gas to 1.1-2.1 MPa.

[0053] S5. The condensate is sequentially passed through ethane tower 212, propylene tower 216 and propane tower 220 to separate ethane, propylene and propane. The propane is then fed into the feed end of feed heat exchanger 15 for further reaction. The pressure of ethane tower 212 is 0.5-2.0 MPa, the pressure of propylene tower 216 is 0.5-1.5 MPa and the pressure of propane tower 220 is 0.3-1.3 MPa.

[0054] This application is also suitable for the production of olefins from liquefied gas, and is also applicable to the dehydrogenation of propane low-carbon hydrocarbons, isobutane and mixtures of one or more of isobutane-rich low-carbon hydrocarbons to produce olefins, with a wide range of applications.

[0055] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A system for propane dehydrogenation to propylene, comprising a reaction regeneration system (1), characterized in that, The reaction regeneration system (1) is connected to a separation system (2) for processing the reaction gas; the separation system (2) includes a water washing tower (201) connected to the reaction regeneration system (1), the top of the water washing tower (201) is connected to a compressor suction tank (209) via a pipe, the top of the compressor suction tank (209) is connected to a reaction gas compressor (210), the reaction gas compressor (210) is connected to a cold box (211), the cold box (211) is connected to an ethane tower (212), and the bottom of the ethane tower (212) is connected to a propylene tower (…). 216), the bottom of the propylene tower (216) is connected to the propane tower (220) via a pipe; the top, middle and bottom of the water washing tower (201) are provided with washing circulation pipelines for circulating washing water, the washing circulation pipelines located in the middle and bottom of the water washing tower (201) are connected, and the washing circulation pipeline at the bottom will divert part of the washing water to the washing circulation pipeline in the middle, the washing circulation pipeline in the middle is provided with a catalyst clarification tank (204) and a clarified water tank (205), and the bottom of the catalyst clarification tank (204) is connected to a settling tank (208).

2. The system for propane dehydrogenation to propylene according to claim 1, characterized in that, The compressor intake tank (209) and the reaction gas compressor (210) are provided in two sets and connected in series for two-stage compression. The bottom of the compressor intake tank (209) is connected to the water washing tower (201).

3. The system for propane dehydrogenation to propylene according to claim 1, characterized in that, The top of the ethane tower (212) is connected to an ethane tower top reflux tank (213), and the pipe connecting the ethane tower (212) and the ethane tower top reflux tank (213) extends into the cold box (211). The bottom of the ethane tower top reflux tank (213) is connected to two pipes, one of which is connected to the ethane tower (212), and the other pipe discharges ethane outward.

4. The system for propane dehydrogenation to propylene according to claim 1, characterized in that, The top of the propylene tower (216) is connected to a propylene tower top reflux tank (217), and the pipe connecting the propylene tower (216) and the propylene tower top reflux tank (217) extends into the cold box (211). The bottom of the propylene tower top reflux tank (217) is connected to two pipes, one of which is connected to the propylene tower (216), and the other pipe discharges propylene outward.

5. The system for propane dehydrogenation to propylene according to claim 1, characterized in that, The top of the propane tower (220) is connected to a propane tower top reflux tank (221), and the pipe connecting the propane tower (220) and the propane tower top reflux tank (221) extends into the cold box (211). The bottom of the propane tower top reflux tank (221) is connected to two pipes, one of which is connected to the propane tower (220), and the other is connected to the feed end of the reaction regeneration system (1).

6. The system for propane dehydrogenation to propylene according to claim 1, characterized in that, The reaction regeneration system (1) includes a feed heat exchanger (15), a heater (13), and a reactor (28) connected in sequence. The bottom of the reactor (28) is connected to a regenerator (27) through a pipe. The bottom of the regenerator (27) is connected to the reactor (28) through a pipe. The top of the reactor (28) is connected to the heat source inlet of the feed heat exchanger (15) through a pipe. The heat source outlet of the feed heat exchanger (15) is connected to a steam generator (16) through a pipe. The steam generator (16) is connected to a water washing tower (201) through a pipe.

7. A system for propane dehydrogenation to propylene according to claim 6, characterized in that, The reactor (28) is equipped with a first and second stage cyclone separator (3), and a third stage cyclone separator (5) is installed on the pipeline connecting the reactor (28) and the feed heat exchanger (15). The bottom of the third stage cyclone separator (5) is connected to a fourth stage cyclone separator (6). The top of the fourth stage cyclone separator (6) is connected to the heat source inlet of the feed heat exchanger (15) through a pipeline. The bottom of the fourth stage cyclone separator (6) is connected to a fine powder collection tank (7), and the fine powder collection tank (7) is connected to a waste catalyst tank (21). A loading device (23) is installed below the waste catalyst tank (21).

8. A system for propane dehydrogenation to propylene according to claim 6, characterized in that, The regenerator (27) is equipped with a first and second stage regeneration cyclone separator (4). The top of the regenerator (27) is connected to a third stage regeneration cyclone separator (8). The top of the third stage regeneration cyclone separator (8) is connected to a waste heat boiler (17) via a pipe, and a double-acting slide valve (26) is installed in the pipe. The waste heat boiler (17) is connected to a flue gas dust collector (18), and the flue gas dust collector (18) is connected to a chimney (19). The bottom of the third stage regeneration cyclone separator (8) is connected to a fourth stage regeneration cyclone separator (9). The top of the fourth stage regeneration cyclone separator (9) is connected to the waste heat boiler (17) via a pipe, and the bottom of the fourth stage regeneration cyclone separator (9) is connected to a regeneration fine powder collection tank (10). The regeneration fine powder collection tank (10) is connected to a waste catalyst tank (21).

9. A method for producing propylene by dehydrogenation of propane, characterized in that, Includes the following steps: S1. Propane is fed into the feed heat exchanger (15). After being heated by the heater (13), the propane enters the reactor (28) and comes into contact with the catalyst to react and generate reaction gas. The catalyst to be generated in the reactor (28) is sent to the regenerator (27) for coking and regeneration to obtain the regenerated catalyst. The regenerated catalyst is then returned to the reactor (28) for continued use. The flue gas generated during the regeneration process of the regenerator (27) passes through the first and second stage cyclone separators (4), the third stage cyclone separator (8), and the fourth stage cyclone separator (9) to separate the catalyst fine powder. Finally, the flue gas passes through the waste heat generator (17) to recover heat and the flue gas dust collector (18) to remove dust before being discharged from the chimney (19). S2. The reaction gas passes through the first and second stage cyclone separators (3), the third stage cyclone separator (5) and the fourth stage cyclone separator (6) in sequence to separate the catalyst fine powder. Then it is fed into the feed heat exchanger (15) as a heat source and then fed into the steam generator (16) for cooling. S3. The cooled reaction gas enters the water washing tower (201) for washing. The water washing tower (201) is equipped with three washing circulation pipelines. The washing circulation pipeline located in the middle of the water washing tower (201) uses the catalyst clarification tank (204) to separate the catalyst and transport it to the settling tank (208) for further separation. S4. The washed reaction gas enters the compressor intake tank (209), and is then compressed by the reaction gas compressor (210) and transported to the cold box (211) to separate the methane hydrogen and condensate. S5. The condensate passes through the ethane tower (212), propylene tower (216) and propane tower (220) in sequence to separate ethane, propylene and propane. The propane is then fed into the feed end of the feed heat exchanger (15) to react again.

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