Ethylene recovery device

Abstract

The utility model discloses an ethylene recovery device which comprises a flash tank, a stirring tank, a first heat exchanger, a second heat exchanger and a gas-liquid separation tank, the top of the flash tank and the top of the stirring tank are both communicated with the gas-liquid separation tank, the first heat exchanger is communicated between the flash tank and the gas-liquid separation tank, and the second heat exchanger is communicated between the stirring tank and the gas-liquid separation tank. The second heat exchanger is communicated between the stirring tank and the gas-liquid separation tank, the bottom of the flash tank is communicated with the stirring tank, and a heating piece is arranged on the stirring tank. According to the device, high-purity ethylene can be effectively separated, the loss of ethylene in a solvent can be reduced, and the recycling rate of ethylene is improved.

Description

Technical Field

[0001] This utility model relates to the field of chemical equipment technology, and in particular to an ethylene recovery device. Background Technology

[0002] Ethylene is an important raw material for the petrochemical industry with extremely wide applications, including synthetic resins, synthetic fibers, synthetic rubber, pharmaceuticals, pesticides, new chemical materials, and daily chemical products. In some ethylene-related chemical production processes, a large amount of tail gas, primarily composed of ethylene, is generated. From an economic perspective, this portion of ethylene often needs to be recovered and reused.

[0003] Current ethylene recovery technologies typically involve feeding ethylene-containing streams into a flash tank for flash evaporation, followed by pressurization and return to the reaction system via a compressor. However, the purity of ethylene recovered in this way is difficult to guarantee. During long-term operation, impurities entrained in the ethylene may deposit in the pipelines or even enter the compressor, causing scaling or corrosion of internal components and affecting the compressor's normal operation, posing certain safety hazards. Furthermore, to avoid excessive liquid entrainment during flash evaporation while meeting the compressor's inlet pressure requirements, flash tanks are generally pressurized. At higher pressures, the solvent in the reaction system has a higher solubility for ethylene, resulting in a significant portion of the ethylene dissolving in the liquid solvent and being discharged without effective recovery. Utility Model Content

[0004] The purpose of this invention is to provide an ethylene recovery device that can effectively separate high-purity ethylene, reduce ethylene loss in the solvent, and improve the ethylene recovery rate.

[0005] To solve the above-mentioned technical problems, this utility model provides the following technical solution:

[0006] An ethylene recovery device includes a flash tank, a stirred tank, a first heat exchanger, a second heat exchanger, and a gas-liquid separator. The top of the flash tank and the top of the stirred tank are both connected to the gas-liquid separator. The first heat exchanger is connected between the flash tank and the gas-liquid separator. The second heat exchanger is connected between the stirred tank and the gas-liquid separator. The bottom of the flash tank is connected to the stirred tank. A heating element is provided on the stirred tank.

[0007] Preferably, the mixing tank is equipped with a stirrer and baffles.

[0008] Preferably, the heating element is a heating sleeve, which is wrapped around the outside of the mixing tank.

[0009] Preferably, the gas-liquid separation tank includes a first gas-liquid separation tank and a second gas-liquid separation tank, the top of the flash tank is connected to the first gas-liquid separation tank, and the top of the stirring tank is connected to the second gas-liquid separation tank.

[0010] Preferably, the first gas-liquid separator and the second gas-liquid separator are interconnected, and a first compressor is connected between them.

[0011] Preferably, it further includes a second compressor, and the first gas-liquid separator is connected to an ethylene output pipe, which is connected to the second compressor.

[0012] Preferably, a first regulating valve is connected between the first heat exchanger and the gas-liquid separator.

[0013] Preferably, a second regulating valve is connected between the second heat exchanger and the gas-liquid separator.

[0014] Preferably, the third regulating valve is connected between the bottom of the flash tank and the stirring tank.

[0015] Preferably, both the first heat exchanger and the second heat exchanger are plate-fin heat exchangers.

[0016] Compared with the prior art, the ethylene recovery device of this utility model has the following advantages:

[0017] In this invention, the flash tank is equipped with a demister. The flash tank is used to flash-evaporate the pressurized product liquid introduced into it, thereby vaporizing the pressurized product liquid. The liquid product liquid flows into the bottom of the flash tank, while the vaporized product liquid is discharged upwards. When passing through the first heat exchanger, it can condense impurities in the ethylene to form condensate that flows back into the flash tank, effectively purifying the ethylene. Then, the ethylene continues to enter the gas-liquid separator for further purification. In addition, since the bottom of the flash tank is connected to the stirred tank, the liquid product liquid in the flash tank simultaneously enters the stirred tank during the flash-evaporation process. Under the heating action of the heating element, it can be further degassed. The resulting ethylene also condenses impurities in the ethylene when passing through the second heat exchanger, and the condensate flows back into the stirred tank, effectively purifying the ethylene. Finally, the ethylene enters the gas-liquid separator. Therefore, the ethylene recovery device, through the installation of flash tank and stirred tank, can fully recover and utilize ethylene to reduce losses. Then, under the action of the first heat exchanger, the second heat exchanger and the gas-liquid separator, the ethylene can be fully purified to effectively separate high-purity ethylene. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the overall structure of an embodiment of the present utility model.

[0019] In the diagram, 1. Flash tank; 2. Stirring tank; 3. First heat exchanger; 4. Second heat exchanger; 5. First gas-liquid separator; 6. Second gas-liquid separator; 7. Stirrer; 8. Heating element; 9. Baffle plate; 10. First compressor; 11. Second compressor; 12. First regulating valve; 13. Second regulating valve; 14. Third regulating valve; 15. Transfer pump; 16. Fourth regulating valve; 17. First discharge valve; 18. Second discharge valve. Detailed Implementation

[0020] The specific embodiments of this utility model will be described in further detail below with reference to the accompanying drawings and examples. The following examples are used to illustrate this utility model, but are not intended to limit its scope.

[0021] In the description of this utility model, it should be understood that the term "comprising" as used in this specification means the presence of the stated features, integers, steps, operations, parts, and / or components, but does not exclude the presence or addition of one or more other features, integers, steps, operations, parts, components, and / or groups thereof. It should be understood that when we say a part is "connected" to another part, it can be directly connected to the other part, or there may be intermediate parts. The term "and / or" as used herein includes all or any unit and all combinations of one or more associated listed items.

[0022] like Figure 1 As shown, this utility model relates to an ethylene recovery device, including a flash tank 1, a stirred tank 2, a first heat exchanger 3, a second heat exchanger 4, and a gas-liquid separator. The top of the flash tank 1 and the top of the stirred tank 2 are both connected to the gas-liquid separator. The first heat exchanger 3 is connected between the flash tank 1 and the gas-liquid separator. The second heat exchanger 4 is connected between the stirred tank 2 and the gas-liquid separator. The bottom of the flash tank 1 is connected to the stirred tank 2. A heating element 8 is provided on the stirred tank 2.

[0023] In this invention, the flash tank 1 is equipped with a demister. The flash tank 1 is used to flash the pressurized product liquid introduced into it to vaporize the pressurized product liquid. The liquid product liquid flows into the bottom of the flash tank 1, and the vaporized product liquid is discharged upward. When passing through the first heat exchanger 3, it can condense impurities in the ethylene to form condensate that flows back into the flash tank 1, effectively purifying the ethylene. Then, the ethylene continues to enter the gas-liquid separator for further purification. In addition, since the bottom of the flash tank 1 is connected to the stirred tank 2, the liquid product liquid in the flash tank 1 simultaneously enters the stirred tank 2 during the flash process. Under the heating action of the heating element 8, it can be further degassed. The ethylene formed can also condense impurities in the ethylene when passing through the second heat exchanger 4. The condensate flows back into the stirred tank 2, effectively purifying the ethylene. Finally, the ethylene enters the gas-liquid separator. Therefore, the ethylene recovery device, through the setup of flash tank 1 and stirred tank 2, can fully recover and utilize ethylene to reduce losses. Then, under the action of the first heat exchanger 3, the second heat exchanger 4 and the gas-liquid separator, ethylene can be fully purified to effectively separate high-purity ethylene, thereby avoiding the corrosion of subsequent equipment by impurities.

[0024] In this embodiment, the mixing tank 2 is equipped with a stirrer 7 and a baffle plate 9, so that the liquid phase product liquid is mixed more evenly and the temperature is more uniform under the action of the stirrer 7 and the baffle plate 9, which is conducive to the separation of ethylene in the mixing tank 2.

[0025] In this embodiment, the heating element 8 is a heating sleeve, which is wrapped around the outside of the stirring tank 2.

[0026] In other words, by wrapping the outside of the mixing tank 2 with a heating jacket, the mixing tank 2 can be heated more evenly, so that the temperature of the liquid product liquid inside can also be more uniform.

[0027] In this embodiment, the gas-liquid separation tank includes a first gas-liquid separation tank 5 and a second gas-liquid separation tank 6. The top of the flash tank 1 is connected to the first gas-liquid separation tank 5, and the top of the stirring tank 2 is connected to the second gas-liquid separation tank 6.

[0028] That is, the ethylene separated by the flash tank 1 enters the first gas-liquid separator 5 for further purification, and the ethylene separated by the stirred tank 2 enters the second gas-liquid separator 6 for further purification.

[0029] Preferably, the first gas-liquid separator 5 and the second gas-liquid separator 6 are interconnected, and a first compressor 10 is connected between them.

[0030] That is, the first compressor 10 can transport the ethylene in the second gas-liquid separator 6 to the first gas-liquid separator 5 so that the ethylene can be extracted for storage and utilization later.

[0031] Furthermore, the ethylene recovery device also includes a second compressor 11, and the first gas-liquid separator 5 is connected to an ethylene output pipe, which is connected to the second compressor 11.

[0032] That is, the outlet of the ethylene output pipe can be connected to an external device, so that the ethylene in the first gas-liquid separator 5 can be transported to the external device through the second compressor 11, so that the recovered ethylene can be utilized.

[0033] In this embodiment, a first regulating valve 12 is connected between the first heat exchanger 3 and the first gas-liquid separator 5, which can be used to control the tank pressure in the flash tank 1.

[0034] In this embodiment, a second regulating valve 13 is connected between the second heat exchanger 4 and the second gas-liquid separator 6, which can be used to control the pressure in the mixing tank 2. Specifically, the second regulating valve 13 can control the pressure of the mixing tank 2 to be in a lower environment, which is conducive to the degassing of the mixing tank 2.

[0035] In this embodiment, the third regulating valve 14 is connected between the bottom of the flash tank 1 and the stirring tank 2, so as to control the liquid level in the flash tank 1.

[0036] In this embodiment, the bottom of the mixing tank 2 is connected to a first liquid delivery pipe, which is equipped with a delivery pump 15 and a fourth regulating valve 16, so that the product liquid in the mixing tank 2 can be discharged.

[0037] In this embodiment, the bottom of the first gas-liquid separator 5 is connected to a second waste liquid conveying pipe, and the second waste liquid conveying pipe is provided with a first discharge valve 17, so that the waste liquid in the first gas-liquid separator 5 can be discharged.

[0038] In this embodiment, the bottom of the second gas-liquid separator 6 is connected to a third waste liquid conveying pipe, and the third waste liquid conveying pipe is equipped with a second discharge valve 18, so that the waste liquid in the second gas-liquid separator 6 can be discharged.

[0039] In this embodiment, both the first heat exchanger 3 and the second heat exchanger 4 are plate-fin heat exchangers, which can efficiently condense impurities in ethylene to improve the purification quality and efficiency of ethylene.

[0040] To illustrate the beneficial effects of this utility model, this embodiment and comparative example will be used for explanation.

[0041] This embodiment:

[0042] The pressurized product liquid originates from the tubular process for preparing norbornene, comprising approximately 25 wt% norbornene, approximately 72 wt% toluene (the solvent), and approximately 3 wt% ethylene and other impurities. The pressurized product liquid enters flash tank 1 for flash evaporation, with the first regulating valve 12 controlling the pressure in flash tank 1 at 0.5-1 MPa. The flash-evaporated ethylene, after being condensed and purified by a plate-fin heat exchanger, enters the first gas-liquid separator 5. The condensed liquid product is returned to flash tank 1, which uses 5°C chilled water as the refrigerant. The ethylene in the first gas-liquid separator 5 is pressurized by the second compressor 11 and returned to the tubular reactor for recycling. The liquid product in flash tank 1 is introduced into stirred tank 2 from the bottom, with the third regulating valve 14 controlling the liquid level in flash tank 1 at 40%. After entering stirred tank 2, the product liquid undergoes further degassing under stirring and heating, separating ethylene. The second regulating valve 13 controls the pressure in stirred tank 2 at -0. The pressure is 0.02-0.05 MPa, the stirring speed is 200 rpm, and the temperature is controlled at 40-60℃. The ethylene recovered from degassing in the stirred tank 2 is condensed and purified by a plate-fin heat exchanger before entering the second gas-liquid separator 6. The condensed liquid product is returned to the stirred tank 2. The plate-fin heat exchanger uses 5℃ chilled water as the refrigerant. The ethylene in the second gas-liquid separator 6 is pressurized by the first compressor 10 and then fed into the first gas-liquid separator 5. It is then pressurized by the second compressor 11 and returned to the tubular reactor. The degassed product liquid in the stirred tank 2 is finally transported to the outside of the system by the transfer pump 15. The fourth regulating valve 16 controls the liquid level in the stirred tank 2 to be 30%. Waste liquid is discharged periodically through the first discharge valve 17 and the second discharge valve 18. The consumption rate of fresh ethylene is measured according to the ethylene flow meter, and the results are listed in Table 1 below.

[0043] Comparative example:

[0044] The pressurized product liquid comes from the tubular process for preparing norbornene, in which norbornene accounts for approximately 25 wt%, toluene (solvent) accounts for approximately 72 wt%, and ethylene and other impurities account for approximately 3 wt%. The pressurized product liquid enters flash tank 1 for flash evaporation, with the first regulating valve 12 controlling the pressure in flash tank 1 at 0.5-1 MPa. The flash-evaporated ethylene, after being condensed and purified by a plate-fin heat exchanger, enters the first gas-liquid separator 5. The condensed liquid product liquid is returned to flash tank 1. The plate-fin heat exchanger uses 5°C chilled water as the refrigerant. The ethylene in the first gas-liquid separator 5 is pressurized by the second compressor 11 and returned to the tubular reactor for recycling. The liquid product liquid in flash tank 1 is transported from the bottom to the outside of the system, and waste liquid is discharged periodically through the first discharge valve 17. The consumption rate of fresh ethylene is measured using an ethylene flow meter, and the results are listed in Table 1 below.

[0045] Table 1 Consumption rate of norbornene ethylene preparation by tubular process.

[0046]

[0047] In other words, by using the ethylene recovery device of this invention, the ethylene consumption rate approaches the theoretical reaction rate, indicating that the ethylene dissolved in the product liquid is effectively recovered and utilized, significantly reducing ethylene waste.

[0048] The above description is only a preferred embodiment of the present utility model. It should be noted that for those skilled in the art, several improvements and substitutions can be made without departing from the technical principles of the present utility model, and these improvements and substitutions should also be considered within the protection scope of the present utility model.

Claims

1. An ethylene recovery device, characterized by, The device comprises a flash tank, a stirring tank, a first heat exchanger, a second heat exchanger and a gas-liquid separation tank, the top of the flash tank and the top of the stirring tank are communicated with the gas-liquid separation tank, the first heat exchanger is communicated between the flash tank and the gas-liquid separation tank, the second heat exchanger is communicated between the stirring tank and the gas-liquid separation tank, the bottom of the flash tank is communicated with the stirring tank, and a heating element is arranged on the stirring tank.

2. The ethylene recovery device of claim 1, wherein, The stirring tank is provided with a stirrer and a baffle.

3. The ethylene recovery device of claim 1, wherein, The heating element is a heating jacket which is wrapped outside the stirring tank.

4. The ethylene recovery device of claim 1, wherein, The gas-liquid separation tank comprises a first gas-liquid separation tank and a second gas-liquid separation tank, the top of the flash tank is communicated with the first gas-liquid separation tank, and the top of the stirring tank is communicated with the second gas-liquid separation tank.

5. The ethylene recovery device of claim 4, wherein, The first gas-liquid separation tank and the second gas-liquid separation tank are communicated with each other, and a first compressor is communicated between the first gas-liquid separation tank and the second gas-liquid separation tank.

6. The ethylene recovery device of claim 5, wherein, A second compressor is further arranged, and an ethylene output pipe is communicated with the first gas-liquid separation tank, and the second compressor is communicated with the ethylene output pipe.

7. The ethylene recovery device of claim 1, wherein, A first regulating valve is communicated between the first heat exchanger and the gas-liquid separation tank.

8. The ethylene recovery device of claim 1, wherein, A second regulating valve is communicated between the second heat exchanger and the gas-liquid separation tank.

9. The ethylene recovery device of claim 1, wherein, A third regulating valve is communicated between the bottom of the flash tank and the stirring tank.

10. The ethylene recovery device of claim 1, wherein, The first heat exchanger and the second heat exchanger are both plate-fin heat exchangers.

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