CN108645119B - Cryogenic separation device and method for propane dehydrogenation product gas - Google Patents
Cryogenic separation device and method for propane dehydrogenation product gas Download PDFInfo
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- CN108645119B CN108645119B CN201810611992.XA CN201810611992A CN108645119B CN 108645119 B CN108645119 B CN 108645119B CN 201810611992 A CN201810611992 A CN 201810611992A CN 108645119 B CN108645119 B CN 108645119B
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- alkyne
- product gas
- diene
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- deethanizer
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
- F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
- F25J3/00—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification
- F25J3/02—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by rectification, i.e. by continuous interchange of heat and material between a vapour stream and a liquid stream
- F25J3/0228—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by rectification, i.e. by continuous interchange of heat and material between a vapour stream and a liquid stream characterised by the separated product stream
- F25J3/0242—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by rectification, i.e. by continuous interchange of heat and material between a vapour stream and a liquid stream characterised by the separated product stream separation of CnHm with 3 carbon atoms or more
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
- F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
- F25J3/00—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification
- F25J3/02—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by rectification, i.e. by continuous interchange of heat and material between a vapour stream and a liquid stream
- F25J3/0228—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by rectification, i.e. by continuous interchange of heat and material between a vapour stream and a liquid stream characterised by the separated product stream
- F25J3/0252—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by rectification, i.e. by continuous interchange of heat and material between a vapour stream and a liquid stream characterised by the separated product stream separation of hydrogen
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
- F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
- F25J3/00—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification
- F25J3/02—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by rectification, i.e. by continuous interchange of heat and material between a vapour stream and a liquid stream
- F25J3/0295—Start-up or control of the process; Details of the apparatus used, e.g. sieve plates, packings
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
- F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
- F25J2270/00—Refrigeration techniques used
- F25J2270/66—Closed external refrigeration cycle with multi component refrigerant [MCR], e.g. mixture of hydrocarbons
Abstract
The invention discloses a deep cooling separation device and method for propane dehydrogenation product gas, comprising a product gas compression drying system, a cold box heat exchanger, an alkyne-removing diene system, a deethanizer and a propylene rectifying tower, wherein the product gas compression drying system is connected with the cold box heat exchanger, the propane dehydrogenation product gas is sent to the cold box heat exchanger for fractional condensation after being compressed and dried to form condensate and low-temperature condensate, the condensate is sent to the deethanizer after alkyne and diene are removed by the alkyne-removing diene system, the deethanizer can receive the low-temperature condensate and convey gas-phase light components to the cold box heat exchanger, and the liquid-phase components of the deethanizer are output to the propylene rectifying tower for rectification to obtain propylene products. The propane dehydrogenation product gas cryogenic separation process adopts mixed refrigerant compression refrigeration, can provide wider refrigeration temperature range and more refrigerant temperature levels, reduces the number of movable equipment, and reduces a large amount of equipment investment and operation maintenance cost compared with the conventional refrigeration separation process.
Description
Technical Field
The invention relates to the field of petrochemical industry, in particular to a propane dehydrogenation product gas cryogenic separation device and a propane dehydrogenation product gas cryogenic separation method.
Background
Propylene is an important petrochemical basic raw material and plays an important role in national economy. In the previous years, the internationally traditional methods for producing propylene products mainly comprise petroleum product cracking, petroleum product catalytic cracking and the like. At present, catalytic dehydrogenation of propane, olefin preparation from methanol and propylene preparation from methanol are also new important ways for producing propylene, in the past, propane is mainly derived from oilfield associated gas, the yield is relatively low, a conditional place can be used as a raw material of a light hydrocarbon cracking furnace for producing propylene products, propane in most areas can not be used as liquefied gas products because of being capable of being formed into a scale, a propane dehydrogenation catalyst is extremely expensive, and a device for producing propylene by international propane dehydrogenation is pineapple horn; however, with the continuous progress and maturity of shale gas exploitation technology, the exploitation amount of shale gas is larger and larger, the exploitation cost of shale gas is lower and lower, and accordingly the accompanying propane amount is larger and larger, the price of propane is lower and lower, the cost of producing propylene through catalytic dehydrogenation of propane is lower and the device for producing propylene through dehydrogenation of propane is more and more. At present, three technologies for realizing industrialized production of propane at home and abroad are adopted, and the largest two technologies are adopted internationally, namely, one technology is a moving bed propane catalytic dehydrogenation technology of UOP, the other technology is a fixed bed propane catalytic dehydrogenation technology of Rums, and more UOP moving bed catalytic dehydrogenation technologies are adopted at home. Whether UOP moving bed catalytic dehydrogenation or Rums fixed bed propane catalytic dehydrogenation, the cryogenic separation technology is adopted for product gas separation refrigeration. UOP adopts a deep cooling technology of propylene refrigeration and a two-stage expander. Because of the characteristic of the composition of the propane dehydrogenation product gas, the method for effectively recycling the hydrogen tail gas is deep cooling, and the product gas is cooled to a certain temperature under a certain pressure, so that the three carbon components in the product gas are liquefied and separated. The gas separation pressure of the propane dehydrogenation products of the UOP and the Rums technology which are put into production and under construction at home is about 1.1MPa, the Rums technology uses the cascade refrigeration technology of propylene refrigeration and ethylene refrigeration, and the minimum refrigeration temperature is about minus 100 ℃; the UOP technology adopts a deep cooling technology of propylene refrigeration and a two-stage expander, the lowest refrigeration temperature is 130 ℃ below zero, and the hydrogen expander has high cost and poor refrigeration effect; the crude hydrogen after expansion and depressurization is further compressed by the pressure swing adsorption hydrogen production unit. The traditional ethylene separation process adopts an overlapping refrigeration method of propylene refrigeration and ethylene refrigeration, and the overlapping refrigeration is completed by a propylene refrigeration unit and an ethylene refrigeration unit. The process equipment is more, the refrigeration effect is poor, and the separation effect is not ideal enough.
Disclosure of Invention
In view of the above, the invention aims to provide a propane dehydrogenation product gas cryogenic separation device and a propane dehydrogenation product gas cryogenic separation method, which have the advantages of simplified process equipment, good refrigeration effect and good separation effect.
According to one aspect of the invention, a cryogenic separation device for propane dehydrogenation product gas is provided, and the cryogenic separation device comprises a product gas compression drying system, a cold box heat exchanger, an alkyne-removing diene system, an ethane-removing system and a propylene rectifying tower, wherein the product gas compression drying system is connected with the cold box heat exchanger, the propane dehydrogenation product gas is compressed and dried and then is sent to the cold box heat exchanger to be subjected to fractional condensation to form condensate and low-temperature condensate, the cold box heat exchanger is connected with the feeding end of the alkyne-removing diene system, the discharging end of the alkyne-removing diene system is connected with the input end of the ethane-removing system, the condensate enters the alkyne-removing diene system to remove alkyne and diene and then is sent to the ethane-removing system, the ethane-removing system is connected with the cold box heat exchanger in a bidirectional manner to receive the low-temperature condensate and send gas-phase light components to the cold box heat exchanger, and the output end of the ethane-removing system is connected with the input end of the propylene rectifying tower.
In some embodiments, the propane dehydrogenation product gas cryogenic separation device further comprises a mixed refrigerant refrigeration system connected to the cold box heat exchanger and forming a refrigeration loop.
In some embodiments, the deethanizer system comprises a low pressure deethanizer and a high pressure deethanizer.
In some embodiments, the dealkylation diene system comprises a dealkylation diene reaction feeding system and a dealkylation diene reaction system, the cold box heat exchanger is connected with the feeding end of the dealkylation diene reaction feeding system, the discharging end of the dealkylation diene reaction feeding system is connected with the feeding end of the dealkylation diene reaction system, condensate is fed into the dealkylation diene reaction feeding system for pressurizing and heating, and then is fed into the dealkylation diene reaction system for hydrogenation to convert alkyne and diene into propylene or propane, and the output end of the dealkylation diene reaction system is connected with the input end of the deethanation system.
In some embodiments, the propane dehydrogenation product gas cryogenic separation device further comprises a pressure swing adsorption device connected to the cold box heat exchanger to receive the hydrogen-rich tail gas output by the cold box heat exchanger.
According to another aspect of the present invention, there is provided a process for the cryogenic separation of propane dehydrogenation product gas comprising the steps of:
s1, pumping the product gas of the propane dehydrogenation device through a product gas compression drying system, removing water, then sending the product gas into a cold box heat exchanger, and cooling the product gas to condensate and low-temperature condensate with different components at different temperatures through heat exchange and cooling of the heat exchanger;
s2, sending condensate into an alkyne-removal diene system for pressurizing and heating, then carrying out hydrogenation reaction, removing alkyne and diene in the material, and then sending the material into a deethanizer system for separating C3 heavy components from methane and ethane light components;
and S3, conveying the liquid-phase heavy components in the condensed liquid in the deethanization system to a propylene rectifying tower for rectification to obtain a propylene product and circulating propane.
In some embodiments, in S1, the product gas is condensed to-15 ℃ to obtain condensate with a component of more than 90% of C3 and a small amount of C4+, and then the product gas is condensed to-40 ℃ to obtain low-temperature condensate with a component of 0.60-0.70% of H2, more than 85% of C3 and a small amount of methane-carbon two.
In some embodiments, the alkyne-removing diene system comprises an alkyne-removing diene reaction feeding system and an alkyne-removing diene reaction system, wherein the alkyne-removing diene reaction feeding system is used for pressurizing and heating condensate, and then sending the condensate into the alkyne-removing diene reaction system for hydrogenation reaction, so that alkyne, diene and hydrogen in product gas react to generate propylene or propane.
In some embodiments, the deethanizer comprises a low-pressure deethanizer and a high-pressure deethanizer, the outlet materials of the deethanized diene reaction system are cooled and then enter the high-pressure deethanizer to separate C3 from light components such as methane and ethane, the C3 in the bottom of the high-pressure deethanizer is sent to the propylene rectifying tower, and the top of the high-pressure deethanizer contains carbon three, methane and ethane tail gas which is cooled and depressurized and then is sent to the low-pressure deethanizer.
In some embodiments, the low-temperature condensate enters a low-pressure deethanizer, the material at the bottom of the low-pressure deethanizer is heated and enters a propylene rectifying tower, and the carbon two and light components at the top of the low-pressure deethanizer return to a cold box heat exchanger for rewarming and recycling.
The beneficial effects of the invention are as follows: the propane dehydrogenation product gas cryogenic separation process provided by the invention adopts mixed refrigerant compression refrigeration, can provide a wider refrigeration temperature range and more refrigerant temperature levels, and can meet the refrigeration requirements of propane dehydrogenation product gas component fluctuation and different separation processes by adjusting the refrigerant proportion. The propane dehydrogenation product gas is condensed into liquids with different temperatures and different components under a plurality of temperature-level coolants, so that the heat transfer temperature difference between the hot flow and the cold flow in the heat exchanger is always lower, and the operation energy consumption of the device is reduced; and only one refrigeration compressor is needed, so that the number of movable equipment is reduced, and a great amount of equipment investment and operation and maintenance cost are reduced compared with the conventional refrigeration separation process.
Drawings
FIG. 1 is a process flow diagram of a propane dehydrogenation product gas cryogenic separation device in accordance with an embodiment of the present invention;
fig. 2 is a schematic structural diagram of a cold box heat exchanger of the propane dehydrogenation product gas cryogenic separation device shown in fig. 1.
Detailed Description
The invention is described in further detail below with reference to the accompanying drawings.
Example 1
Figures 1 and 2 schematically illustrate a propane dehydrogenation product gas cryogenic separation plant in accordance with one embodiment of the present invention.
Referring to fig. 1 and 2, the propane dehydrogenation product gas cryogenic separation device comprises a product gas compression drying system 1, a cold box heat exchanger 2, an alkyne diene system 3, a mixed refrigerant refrigeration system 4, a deethanizer system 5, a propylene rectifying tower 6 and a pressure swing adsorption device 7. The product gas compression drying system 1 is connected with the cold box heat exchanger 2, and the propane dehydrogenation product gas is compressed and dried by the product gas compression drying system 1 and then is sent into the cold box heat exchanger 2 for fractional condensation to form condensate and low-temperature condensate. The cold box heat exchanger 2 is connected with the feeding end of the alkyne-removing diene system 3, and the discharging end of the alkyne-removing diene system 3 is connected with the input end of the deethanizer system 5. The condensate enters the alkyne and diene removal system 3 and then is sent to the deethanizer system 5, the deethanizer system 5 is in bidirectional connection with the cold box heat exchanger 2, and the deethanizer system 5 receives the low-temperature condensate output by the cold box heat exchanger 2 and the materials output by the alkyne and diene removal system 3 and performs gas-liquid separation. The gas phase light component separated by the deethanizer 5 returns to the cold box heat exchanger 2 for rewarming and can be used as fuel of the fuel gas system. The output end of the deethanizer 5 is connected with the input end of the propylene rectifying tower 6, and the liquid phase component output by the deethanizer 5 is sent into the propylene rectifying tower 6 for rectification. The pressure swing adsorption device 7 is connected with the cold box heat exchanger 2 to receive the hydrogen-rich tail gas output by the cold box heat exchanger 2.
The cold box heat exchanger 2 may include a primary heat exchanger 21, a secondary heat exchanger 22, a primary gas-liquid separator 23, and a secondary gas-liquid separator 24. The output end of the product gas compression drying system 1 is connected with the input end of the first-stage gas-liquid separator 23, and the product gas output by the product gas compression drying system 1 is condensed to-15 ℃ by the first-stage heat exchanger 21 and then is sent to the first-stage gas-liquid separator 23 for gas-liquid separation. The liquid phase material separated by the primary gas-liquid separator 23 is condensate with the components of more than 90% of C3 and a small amount of C4+, and the liquid phase output end of the primary gas-liquid separator 23 is connected with the alkyne-removing diene system 3 and can convey the condensate to the alkyne-removing diene system 3. The gas phase output end of the primary gas-liquid separator 23 is connected with the input end of the secondary gas-liquid separator 24, and the gas phase material output by the primary gas-liquid separator 23 is condensed to-40 ℃ by the secondary heat exchanger 22 and then is sent into the secondary gas-liquid separator 24 for gas-liquid separation. The liquid phase separated by the secondary gas-liquid separator 24 is H2 with the component of 0.60-0.70%, C3 with the component of more than 85% and a small amount of methane, and the gas phase is hydrogen-rich tail gas. The liquid phase output end of the secondary gas-liquid separator 24 is connected with the deethanizer system 5, and the gas phase output end of the secondary gas-liquid separator 24 is connected with the pressure swing adsorption device 7.
The mixed refrigerant refrigeration system 4 is connected with the cold box heat exchanger 2 and forms a refrigeration circuit. The mixed refrigerant refrigerating system 4 adopts mixed refrigerant which is mixed by different proportions of components such as methane, ethylene, propane, isopentane, nitrogen and the like, and can provide refrigeration capacity in a temperature range of 5 ℃ to minus 190 ℃. The specific components of the invention are 10 to 15 percent of methane, 40 to 45 percent of ethylene, 12 to 25 percent of propane, 10 to 18 percent of isopentane and 5 to 8 percent of nitrogen.
The mixed refrigerant refrigeration system 4 consists of a refrigeration compressor unit, a refrigerant balance tank and a throttle valve.
The dealkyne diene system 3 includes a dealkyne diene reaction feed system 31 and a dealkyne diene reaction system 32. The cold box heat exchanger 2 is connected with the feed end of the alkyne-removing diene reaction feed system 31, and the discharge end of the alkyne-removing diene reaction feed system 31 is connected with the feed end of the alkyne-removing diene reaction system 32. The condensate is sent to the alkyne-removing diene reaction feeding system 31 for pressurizing and heating, and then sent to the alkyne-removing diene reaction system 32 for hydrogenation reaction to convert alkyne and diene into propylene or propane, and the output end of the alkyne-removing diene reaction system 32 is connected with the input end of the deethanization system 5.
Deethanizer system 5 includes a low pressure deethanizer 51 and a high pressure deethanizer 52. A low pressure deethanizer 51 is connected to the desacetylenic diene reaction system 32 to receive the vapor phase feed from the desacetylenic diene reaction system 32. High pressure deethanizer 52 is connected to the desacetylenic diene reaction system 32 to receive the liquid phase feed from the desacetylenic diene reaction system 32. The output end of the low-pressure deethanizer 51 and the output end of the high-pressure deethanizer 52 are both connected with the input end of the propylene rectifying tower 6 and convey liquid-phase materials to the propylene rectifying tower 6. The feed end of the low pressure deethanizer 51 is connected to the liquid phase output end of the secondary gas-liquid separator 24 to receive the cryogenic condensate. The high-pressure deethanizer 52 is connected to the low-pressure deethanizer 51, and the off-gas containing a large amount of C3 produced at the top of the high-pressure deethanizer 52 is fed to the low-pressure deethanizer 51.
Example 2
The cryogenic separation method of propane dehydrogenation product gas comprises the following steps:
s1, pumping the product gas of the propane dehydrogenation device through a product gas compression drying system 1, then sending the product gas into a cold box heat exchanger 2, and cooling the product gas to condensate and low-temperature condensate with different components at different temperatures through heat exchange and cooling of the heat exchanger;
the first-stage heat exchanger 21 of the cold box heat exchanger 2 condenses the product gas to-15 ℃, then sends the condensed gas to the first-stage gas-liquid separator 23 for gas-liquid separation to obtain condensate with the component of C3 and less C4+ above 90%, and the gas phase is condensed to-40 ℃ by the second-stage heat exchanger 22 and then sent to the second-stage gas-liquid separator 24 for gas-liquid separation to obtain low-temperature condensate with the component of H2 of 0.60-0.70%, C3 above 85% and less methane and hydrogen-rich tail gas containing a large amount of H2.
S2, sending the condensate into an alkyne-removing diene system 3 for hydrogenation reaction after pressurizing and heating, removing alkyne and diene in the material, and sending the material into a high-pressure deethanizer 52 of a deethanizer 5 for separating C3 heavy components from methane and ethane light components.
The dealkyne diene system 3 includes a dealkyne diene reaction feed system 31 and a dealkyne diene reaction system 32. The condensate is pressurized to 3.5MPa by the alkyne-removing diene reaction feeding system 31 and heated to about 45 ℃, and then the condensate is sent to the alkyne-removing diene reaction system 32 for hydrogenation reaction, so that alkyne, diene and hydrogen in the product gas react to generate propylene or propane.
And S3, conveying the liquid phase component condensed in the deethanizer 5 to a propylene rectifying tower 6 for rectification, and reacting alkyne, diene and hydrogen to generate propylene or propane under the action of a catalyst. Obtaining propylene product and recycle propane. The circulating propane is extracted from the tower bottom of the propylene rectifying tower 6, vaporized and refrigerated at low pressure and then enters a heating system as a raw material for propane dehydrogenation.
The deethanizer system 5 comprises a low-pressure deethanizer 51 and a high-pressure deethanizer 52, wherein the materials at the outlet of the deethanizer diene reaction system 32 are cooled and then enter the high-pressure deethanizer 52 to separate C3 from light components such as methane and ethane, the C3 at the tower bottom of the high-pressure deethanizer 52 is sent to the propylene rectifying tower 6, and part of the carbon three and methane tail gas at the tower top of the high-pressure deethanizer is sent to the low-pressure deethanizer 51 after being cooled and depressurized.
The pressure in the high-pressure deethanizer 52 is 1.8-2.5 MPa, in the high-pressure deethanizer 52, the liquid phase heavy components in the condensate flow to the bottom of the tower due to gravity, and the light components methane, ethane and the like in the condensate are gasified into gas and flow out of the deethanizer, so that the separation of C3, methane, ethane and the like light components is realized. The mixed carbon three materials at the tower bottom of the high-pressure deethanizer 52 enter the propylene rectifying tower 6 by self pressure, and the gas phase components are sent into the low-pressure deethanizer 51 to be used as the feed of the low-pressure deethanizer 51. The low temperature condensate separated by the secondary gas-liquid separator 24 is also fed into the low pressure deethanizer 51 as feed to the low pressure deethanizer 51. The mixed carbon three materials at the bottom of the low-pressure deethanizer 51 are pumped out and then enter the propylene rectifying tower 6 after being heated. The second carbon and light components at the top of the low-pressure deethanizer 51 return to the cold box heat exchanger for rewarming to normal temperature, and then can enter a fuel gas system for combustion.
The mixed carbon III entering the propylene rectifying tower 6 is separated into propylene products and circulating propane in the propylene rectifying tower 6, the propylene products are extracted from the top of the propylene rectifying tower 6, the circulating propane is extracted from the tower bottom of the propylene rectifying tower 6, and the propylene products are vaporized and refrigerated at low pressure and then enter a heating system as raw materials for dehydrogenation of propane.
S4, reheating the low-temperature hydrogen-rich tail gas obtained after deep cooling, and sending the low-temperature hydrogen-rich tail gas to the pressure swing adsorption device 7 to prepare hydrogen.
The invention discloses a propane dehydrogenation product gas cryogenic separation process. Aiming at the difference of boiling points of the gas components of the propane dehydrogenation product, the separation is carried out in different temperature areas by adopting a low-temperature rectification mode, and mixed refrigerant refrigeration is adopted to replace the original cascade refrigeration. The new separation process system comprises a raw material gas compression and drying system, an alkyne and diene removal reactor, a main heat exchanger, a deethanizer system, a propylene rectifying tower, a refrigerating system and a pressure swing adsorption hydrogen extraction system. The refrigerating system adopts mixed refrigerant for refrigeration, and adopts different refrigerant combinations for gradual condensation and evaporation to obtain cold energy with different temperature levels, so as to achieve the purposes of gradual cooling and liquefaction separation of raw gas components. The process method is simple and convenient to operate, reduces the number of movable equipment, reduces investment and maintenance cost, reduces the operation energy consumption of the device by 10 percent compared with the prior process method, and has good energy-saving effect and economic benefit.
What has been described above is merely some embodiments of the present invention. It will be apparent to those skilled in the art that various modifications and improvements can be made without departing from the spirit of the invention.
Claims (10)
1. The propane dehydrogenation product gas cryogenic separation device is characterized by comprising a product gas compression drying system (1), a cold box heat exchanger (2), an alkyne and diene system (3), a deethanization system (5) and a propylene rectifying tower (6), wherein the product gas compression drying system (1) is connected with the cold box heat exchanger (2), the propane dehydrogenation product gas is sent to the cold box heat exchanger (2) for fractional condensation after compression drying to form condensate and low-temperature condensate, the cold box heat exchanger (2) is connected with the feed end of the alkyne diene system (3), the discharge end of the alkyne diene system (3) is connected with the input end of the deethanization system (5), the condensate is sent to the deethanization system (5) after being subjected to the alkyne and diene removal by the deethanization system (3), the deethanization system (5) is connected with the cold box heat exchanger (2) in a bidirectional manner to receive the low-temperature condensate and send gas-phase light components to the cold box heat exchanger (2), and the output end of the deethanization system (5) is connected with the input end of the propylene rectifying tower (6).
2. The propane dehydrogenation product gas cryogenic separation device according to claim 1, further comprising a mixed refrigerant refrigeration system (4), wherein the mixed refrigerant refrigeration system (4) is connected with the cold box heat exchanger (2) and forms a refrigeration loop.
3. The propane dehydrogenation product gas cryogenic separation device according to claim 2, characterized in that the deethanizer system (5) comprises a low pressure deethanizer (51) and a high pressure deethanizer (52).
4. The propane dehydrogenation product gas cryogenic separation device according to claim 1, wherein the alkyne removal diene system (3) comprises an alkyne removal diene reaction feeding system (31) and an alkyne removal diene reaction system (32), the cold box heat exchanger (2) is connected with the feeding end of the alkyne removal diene reaction feeding system (31), the discharging end of the alkyne removal diene reaction feeding system (31) is connected with the feeding end of the alkyne removal diene reaction system (32), condensate is sent into the alkyne removal diene reaction feeding system (31) for pressurizing and heating, and then is sent into the alkyne removal diene reaction system (32) for hydrogenation to convert alkyne and diene into propylene or propane, and the output end of the alkyne removal diene reaction system (32) is connected with the input end of the ethane removal system (5).
5. The propane dehydrogenation product gas cryogenic separation device according to any one of claims 1-4, further comprising a pressure swing adsorption device (7), wherein the pressure swing adsorption device (7) is connected with the cold box heat exchanger (2) to receive hydrogen-rich tail gas output by the cold box heat exchanger (2).
6. The cryogenic separation method for the propane dehydrogenation product gas is characterized by comprising the following steps of:
s1, pumping product gas of a propane dehydrogenation device through a product gas compression drying system (1), then sending the product gas into a cold box heat exchanger (2), and cooling the product gas to condensate and low-temperature condensate with different components at different temperatures through heat exchange and cooling of the heat exchanger;
s2, sending condensate into an alkyne-removing diene system (3), pressurizing and heating, then carrying out hydrogenation reaction, removing alkyne and diene in the materials, and then sending the materials into a deethanizer system (5) for separating C3 heavy components from methane and ethane light components;
s3, conveying the liquid-phase heavy components in the condensed liquid in the deethanizer (5) to a propylene rectifying tower (6) for rectification to obtain a propylene product and circulating propane.
7. The method for cryogenic separation of propane dehydrogenation product gas according to claim 6, wherein in the step S1, the product gas is condensed to-15 ℃ to obtain condensate with a component of more than 90% of C3 and a small amount of C4+, and then the product gas is condensed to-40 ℃ to obtain low-temperature condensate with a component of 0.60-0.70% of H2, more than 85% of C3 and a small amount of methane.
8. The method for cryogenic separation of propane dehydrogenation product gas according to claim 6, wherein the alkyne-removal diene system (3) comprises an alkyne-removal diene reaction feeding system (31) and an alkyne-removal diene reaction system (32), and the alkyne-removal diene reaction feeding system (31) is used for pressurizing and heating condensate, and then sending the condensate into the alkyne-removal diene reaction system (32) for hydrogenation reaction, so that alkyne, diene and hydrogen in product gas react to generate propylene or propane.
9. The deep cooling separation method for propane dehydrogenation product gas according to claim 8, wherein the deethanizer system (5) comprises a low-pressure deethanizer column (51) and a high-pressure deethanizer column (52), outlet materials of the deethanized diene reaction system (32) are cooled and enter the high-pressure deethanizer column (52) to separate light components such as C3, methane and ethane, C3 in a tower kettle of the high-pressure deethanizer column (52) is sent to a propylene rectifying tower (6), and methane and ethane tail gas at the top of the high-pressure deethanizer column is sent to the low-pressure deethanizer column (51) after being cooled and depressurized.
10. The method for cryogenic separation of propane dehydrogenation product gas according to claim 8, wherein low-temperature condensate enters a low-pressure deethanizer (51), tower bottom materials of the low-pressure deethanizer (51) enter a propylene rectifying tower (6) after being heated, and carbon two and light components at the tower top of the low-pressure deethanizer (51) are returned to a cold box heat exchanger for re-heating and recycling.
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| CN112939724B (en) * | 2019-12-11 | 2022-09-20 | 中国石油化工股份有限公司 | Recovery device and recovery process for reaction product of propane dehydrogenation propylene preparation |
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| CN114543444A (en) * | 2022-02-28 | 2022-05-27 | 杭州中泰深冷技术股份有限公司 | Multi-refrigerant cold box separation system for propane dehydrogenation and process method |
| CN114992983A (en) * | 2022-03-21 | 2022-09-02 | 江苏卓然恒泰低温科技有限公司 | Low-temperature separation cold box for propane dehydrogenation |
| CN115597309B (en) * | 2022-10-19 | 2023-05-16 | 中科泓能(北京)科技有限公司 | Propane dehydrogenation product separation method and system |
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