Process for adsorbing and separating ethane by using catalytic dry gas

Abstract

The invention discloses a process for adsorbing and separating ethane by using catalytic dry gas, and aims to solve the technical problems that in the prior art, the ethane adsorption effect is relatively poor, an adsorbent is not easy to regenerate, the chemical stability is relatively poor, next adsorption can be carried out only after desorption is completed after adsorption saturation, and the working efficiency is low. The process comprises the following steps: S1, pretreating dry gas; s2, preparing an adsorbent; and S3, the dry gas pretreated in the S1 is pressurized to the pressure condition required by the process through a compressor, and then the dry gas is cooled through circulating water and low-temperature refrigerant water in sequence. According to the process, the adsorbent is prepared by loading copper chloride on activated carbon, the prepared adsorbent has a better adsorption effect on ethane, the adsorbent can be regenerated and is good in chemical stability, and through the design of the two adsorption beds, one adsorption bed performs desorption while the other adsorption bed performs adsorption operation; and continuous adsorption and desorption operation can be realized, and the working efficiency is higher.

Description

Technical Field

[0001] This invention belongs to the field of petrochemical technology, specifically relating to a process for separating ethane by catalytic dry gas adsorption. Background Technology

[0002] Dry gas is an important byproduct of petrochemicals. Ethane separation is an important separation process. Ethane is mainly used as a raw material for the production of ethylene, and can also be used as fuel and refrigerant, as well as in the manufacture of chloroethane and bromoethane, etc.

[0003] Currently, invention patent CN202011391248.7 discloses a method for separating ethylene and ethane from catalytic dry gas. The method is characterized by the following steps: after gas-liquid separation, the catalytic dry gas sequentially passes through a pressure swing adsorption (PSA) unit, a compression unit, a purification unit, and a cryogenic distillation unit to separate ethylene and ethane. The PSA unit removes most of the hydrocarbons (hydrogen, nitrogen, and methane) from the catalytic dry gas, concentrating hydrocarbons with more than two carbon atoms to obtain ethylene-rich gas. The compression unit pressurizes the ethylene-rich concentrated gas. The purification unit removes carbon dioxide, sulfides, arsenic, mercury, nitrogen oxides, and water. The purified gas then enters the cryogenic distillation unit to separate ethylene and ethane, obtaining ethylene with a purity greater than 99.9% and ethane with a purity greater than 98%. The feed gas is catalytic dry gas with a pressure of 0.3–1.0 MPa. The pressure of the feed gas itself is utilized, and no further pressurization is required. The process is simple and consumes less energy than conventional technologies, but it has poor adsorption effect on ethane, the adsorbent is not easy to regenerate, has poor chemical stability, and requires desorption after adsorption saturation before the next adsorption can be carried out, resulting in low working efficiency.

[0004] Therefore, the problems of poor adsorption effect and low working efficiency mentioned above urgently need to be solved in order to improve the application scenarios of dry gas. Summary of the Invention

[0005] (1) Technical problems to be solved

[0006] In view of the shortcomings of the prior art, the purpose of this invention is to provide a process for separating ethane by catalytic dry gas adsorption. This process aims to solve the technical problems of poor adsorption effect of ethane, difficulty in regenerating the adsorbent, poor chemical stability, and low working efficiency under the prior art, which requires desorption after adsorption saturation before the next adsorption can be carried out.

[0007] (2) Technical solution

[0008] To address the aforementioned technical problems, this invention provides a process for separating ethane using catalytic dry gas adsorption, the steps of which are as follows:

[0009] S1: Pre-treatment of dry gas;

[0010] S2: Preparation of adsorbent:

[0011] S21: Place the powdered activated carbon into a vacuum drying oven, set the drying temperature and drying time, and remove and seal it after it cools naturally in the vacuum drying oven.

[0012] S22: Weigh out the same amount of CuCl as the powdered activated carbon, sieve the CuCl, mix the CuCl with the powdered activated carbon, and then grind it.

[0013] S23: Place the mixture of CuCl and powdered activated carbon after grinding into a tube furnace, heat to 400℃ under a nitrogen atmosphere for dispersion treatment, set the heating rate, hold at 120℃ for 30 minutes, calcine at 400℃, keep the tube furnace under a nitrogen atmosphere, cool naturally to room temperature, remove the adsorbent and seal for storage.

[0014] S3: The dry gas pretreated in S1 is pressurized by a compressor to the pressure required by the process, and then cooled by circulating water and low-temperature chilled water in sequence.

[0015] S4: The adsorbent prepared in S2 is added to the adsorption bed, and dry gas is introduced into the adsorption bed. The adsorption temperature and dry gas flow rate are set. C2H6 and C2H4 compete for adsorption on the adsorbent. C2H6 is adsorbed, and the concentration of C2H6 in the adsorbed phase increases, while the concentration of C2H4 in the gas phase increases until the adsorption reaches saturation. Then, the dry gas is cut off, N2 is introduced, and the temperature is raised to desorb and obtain ethane.

[0016] Preferably, the specific steps of the preprocessing in S1 are as follows:

[0017] S11: Dry gas is introduced into the pressure swing adsorption unit to adsorb methane;

[0018] S12: Then it is sent to the compression unit to remove heavy hydrocarbons from the dry gas;

[0019] S13: Then, after passing through the desulfurization and decarbonization unit, H2S in the dry gas is absorbed by MDEA, CO2 is absorbed by NaOH solution, and then H2S is removed to a content ≤0.1μg / g by the fine desulfurization unit;

[0020] S14: After deoxygenation by a deaerator, the gas is cooled to 40°C to separate water, and then pretreated dry gas is obtained after alkaline washing.

[0021] Preferably, the drying temperature in step S21 is 120°C and the drying time is 4-6 hours.

[0022] Preferably, the sieve used to sieve CuCl in S22 has a mesh size of 300-400.

[0023] Preferably, the heating rate in step S23 is 5°C / min, and the calcination time is 4-6 hours.

[0024] Preferably, the pressure condition in S3 is 3.0-4.0 MPa.

[0025] Preferably, the temperature of the cooled dry gas in S3 is 10-15°C.

[0026] Preferably, the adsorption temperature in S4 is 25-60℃ and the dry gas flow rate is 25-60L / min.

[0027] Preferably, the condition for adsorption to reach saturation in S4 is that the outlet gas concentration of C2H6 / C2H4 is the same as the inlet gas concentration.

[0028] (3) Beneficial effects

[0029] Compared with the prior art, the beneficial effects of the present invention are as follows: The process of the present invention uses copper chloride loaded on activated carbon to prepare adsorbent, which has a better adsorption effect on ethane, and the adsorbent can be regenerated and has good chemical stability. Furthermore, through the design of two adsorption beds, one adsorption bed is performing adsorption operation while the other adsorption bed is performing desorption, which can realize continuous and uninterrupted adsorption and desorption operations, resulting in higher work efficiency. In addition, the overall process is simple, easy to control, requires less equipment, and effectively reduces costs. Detailed Implementation

[0030] This specific embodiment utilizes a catalytic dry gas adsorption process to separate ethane, and its steps are as follows:

[0031] S1: Pre-treatment of dry gas;

[0032] S2: Preparation of adsorbent:

[0033] S21: Place the powdered activated carbon into a vacuum drying oven, set the drying temperature and drying time, and remove and seal it after it cools naturally in the vacuum drying oven.

[0034] S22: Weigh out the same amount of CuCl as the powdered activated carbon, sieve the CuCl, mix the CuCl with the powdered activated carbon, and then grind it.

[0035] S23: Place the mixture of CuCl and powdered activated carbon after grinding into a tube furnace, heat to 400℃ under a nitrogen atmosphere for dispersion treatment, set the heating rate, hold at 120℃ for 30 minutes, calcine at 400℃, keep the tube furnace under a nitrogen atmosphere, cool naturally to room temperature, remove the adsorbent and seal for storage.

[0036] S3: The dry gas pretreated in S1 is pressurized by a compressor to the pressure required by the process, and then cooled by circulating water and low-temperature chilled water in sequence.

[0037] S4: The adsorbent prepared in S2 is added to the adsorption bed, and dry gas is introduced into the adsorption bed. The adsorption temperature and dry gas flow rate are set. C2H6 and C2H4 compete for adsorption on the adsorbent. C2H6 is adsorbed, and the concentration of C2H6 in the adsorbed phase increases, while the concentration of C2H4 in the gas phase increases until the adsorption reaches saturation. Then, the dry gas is cut off, N2 is introduced, and the temperature is raised to desorb and obtain ethane.

[0038] Example 1

[0039] The process using this technical solution involves the following steps:

[0040] S1: Pretreatment of dry gas:

[0041] S11: Dry gas is introduced into the pressure swing adsorption unit to adsorb methane;

[0042] S12: Then it is sent to the compression unit to remove heavy hydrocarbons from the dry gas;

[0043] S13: Then, after passing through the desulfurization and decarbonization unit, H2S in the dry gas is absorbed by MDEA, CO2 is absorbed by NaOH solution, and then H2S is removed to a content ≤0.1μg / g by the fine desulfurization unit;

[0044] S14: After deoxygenation by the deaerator, the gas is cooled to 40°C to separate water, and then pretreated dry gas is obtained after alkaline washing.

[0045] S2: Preparation of adsorbent:

[0046] S21: Place the powdered activated carbon in a vacuum drying oven, set the drying temperature and drying time to 120℃ and 6h, and remove and seal it after it cools naturally in the vacuum drying oven.

[0047] S22: Weigh out the same amount of CuCl as the powdered activated carbon, sieve the CuCl, mix the CuCl with the powdered activated carbon and grind them together. The sieve size is 300 mesh.

[0048] S23: Place the mixture of CuCl and powdered activated carbon after grinding into a tube furnace, heat to 400℃ under a nitrogen atmosphere for dispersion treatment, set the heating rate to 5℃ / min, hold at 120℃ for 30min, calcine at 400℃ for 6h, keep in a nitrogen atmosphere in the tube furnace, cool naturally to room temperature, take out the adsorbent and seal it for storage.

[0049] S3: The dry gas pretreated in S1 is pressurized by a compressor to the required pressure of 4.0 MPa, and then cooled by circulating water and low-temperature chilled water in sequence. The temperature after cooling is 15℃.

[0050] S4: The adsorbent prepared in S2 is added to the adsorption bed, and dry gas is introduced into the adsorption bed. The adsorption temperature and dry gas flow rate are set as follows: the adsorption temperature is 60℃ and the dry gas flow rate is 40L / min. C2H6 and C2H4 compete for adsorption on the adsorbent. C2H6 is adsorbed, and the concentration of C2H6 in the adsorbed phase increases, while the concentration of C2H4 in the gas phase increases until the adsorption reaches saturation. The saturation condition is that the outlet gas concentration of C2H6 / C2H4 is the same as the inlet gas concentration. The dry gas is then cut off, N2 is introduced, and the temperature is raised to desorb and obtain ethane.

[0051] The separation factor for ethane using the process described in Example 1 can reach 9.2, and the adsorption capacity for ethane is 16.9 mg / g.

[0052] Example 2

[0053] The process using this technical solution involves the following steps:

[0054] S1: Pretreatment of dry gas:

[0055] S11: Dry gas is introduced into the pressure swing adsorption unit to adsorb methane;

[0056] S12: Then it is sent to the compression unit to remove heavy hydrocarbons from the dry gas;

[0057] S13: Then, after passing through the desulfurization and decarbonization unit, H2S in the dry gas is absorbed by MDEA, CO2 is absorbed by NaOH solution, and then H2S is removed to a content ≤0.1μg / g by the fine desulfurization unit;

[0058] S14: After deoxygenation by the deaerator, the gas is cooled to 40°C to separate water, and then pretreated dry gas is obtained after alkaline washing.

[0059] S2: Preparation of adsorbent:

[0060] S21: Place the powdered activated carbon in a vacuum drying oven, set the drying temperature and drying time to 120℃ and 4h, and remove and seal it after it cools naturally in the vacuum drying oven.

[0061] S22: Weigh out the same amount of CuCl as the powdered activated carbon, sieve the CuCl, mix the CuCl with the powdered activated carbon and grind them together. The sieve size is 300 mesh.

[0062] S23: Place the mixture of CuCl and powdered activated carbon after grinding into a tube furnace, heat to 400℃ under a nitrogen atmosphere for dispersion treatment, set the heating rate to 5℃ / min, hold at 120℃ for 30min, calcine at 400℃ for 5h, keep in a nitrogen atmosphere in the tube furnace, cool naturally to room temperature, take out the adsorbent and seal it for storage.

[0063] S3: The dry gas pretreated in S1 is pressurized by a compressor to the required pressure of 4.0 MPa, and then cooled by circulating water and low-temperature chilled water in sequence. The temperature after cooling is 15℃.

[0064] S4: The adsorbent prepared in S2 is added to the adsorption bed, and dry gas is introduced into the adsorption bed. The adsorption temperature and dry gas flow rate are set as follows: the adsorption temperature is 50℃ and the dry gas flow rate is 50L / min. C2H6 and C2H4 compete for adsorption on the adsorbent. C2H6 is adsorbed, and the concentration of C2H6 in the adsorbed phase increases, while the concentration of C2H4 in the gas phase increases until the adsorption reaches saturation. The saturation condition is that the outlet gas concentration of C2H6 / C2H4 is the same as the inlet gas concentration. The dry gas is then cut off, N2 is introduced, and the temperature is raised to desorb and obtain ethane.

[0065] The separation factor for ethane using the process described in Example 2 can reach 7.7, and the adsorption capacity for ethane is 18.3 mg / g.

[0066] Example 3

[0067] The process using this technical solution involves the following steps:

[0068] S1: Pretreatment of dry gas:

[0069] S11: Dry gas is introduced into the pressure swing adsorption unit to adsorb methane;

[0070] S12: Then it is sent to the compression unit to remove heavy hydrocarbons from the dry gas;

[0071] S13: Then, after passing through the desulfurization and decarbonization unit, H2S in the dry gas is absorbed by MDEA, CO2 is absorbed by NaOH solution, and then H2S is removed to a content ≤0.1μg / g by the fine desulfurization unit;

[0072] S14: After deoxygenation by the deaerator, the gas is cooled to 40°C to separate water, and then pretreated dry gas is obtained after alkaline washing.

[0073] S2: Preparation of adsorbent:

[0074] S21: Place the powdered activated carbon in a vacuum drying oven, set the drying temperature and drying time to 120℃ and 4h, and remove and seal it after it cools naturally in the vacuum drying oven.

[0075] S22: Weigh out the same amount of CuCl as the powdered activated carbon, sieve the CuCl, mix the CuCl with the powdered activated carbon and grind them together. The sieve size is 350 mesh.

[0076] S23: Place the mixture of CuCl and powdered activated carbon after grinding into a tube furnace, heat to 400℃ under a nitrogen atmosphere for dispersion treatment, set the heating rate to 5℃ / min, hold at 120℃ for 30min, calcine at 400℃ for 4h, keep the tube furnace under a nitrogen atmosphere, cool naturally to room temperature, remove the adsorbent and seal for storage.

[0077] S3: The dry gas pretreated in S1 is pressurized by a compressor to the required pressure of 4.0 MPa, and then cooled by circulating water and low-temperature chilled water in sequence. The temperature after cooling is 10℃.

[0078] S4: The adsorbent prepared in S2 is added to the adsorption bed, and dry gas is introduced into the adsorption bed. The adsorption temperature and dry gas flow rate are set as follows: the adsorption temperature is 40℃ and the dry gas flow rate is 60L / min. C2H6 and C2H4 compete for adsorption on the adsorbent. C2H6 is adsorbed, and the concentration of C2H6 in the adsorbed phase increases, while the concentration of C2H4 in the gas phase increases until the adsorption reaches saturation. The saturation condition is that the outlet gas concentration of C2H6 / C2H4 is the same as the inlet gas concentration. The dry gas is then cut off, N2 is introduced, and the temperature is raised to desorb and obtain ethane.

[0079] The separation factor of ethane obtained by the process in Example 3 can reach 10, and the adsorption capacity of ethane is 19.5 mg / g.

Claims

1. A process for separating ethane using catalytic dry gas adsorption, characterized in that, The steps are as follows: S1: Pre-treatment of dry gas; S2: Preparation of adsorbent: S21: Place the powdered activated carbon into a vacuum drying oven, set the drying temperature and drying time, and remove and seal it after it cools naturally in the vacuum drying oven. S22: Weigh out the same amount of CuCl as the powdered activated carbon, sieve the CuCl, mix the CuCl with the powdered activated carbon, and then grind it. S23: Place the mixture of CuCl and powdered activated carbon after grinding into a tube furnace, heat to 400℃ under a nitrogen atmosphere for dispersion treatment, set the heating rate, hold at 120℃ for 30 minutes, calcine at 400℃, keep the tube furnace under a nitrogen atmosphere, cool naturally to room temperature, remove the adsorbent and seal for storage. S3: The dry gas pretreated in S1 is pressurized by a compressor to the pressure required by the process, and then cooled by circulating water and low-temperature chilled water in sequence. S4: The adsorbent prepared in S2 is added to the adsorption bed, and dry gas is introduced into the adsorption bed. The adsorption temperature and dry gas flow rate are set. C2H6 and C2H4 compete for adsorption on the adsorbent. C2H6 is adsorbed, and the concentration of C2H6 in the adsorbed phase increases, while the concentration of C2H4 in the gas phase increases until the adsorption reaches saturation. Then, the dry gas is cut off, N2 is introduced, and the temperature is raised to desorb ethane. At the same time, dry gas is introduced into another adsorption bed, and adsorption is carried out.

2. The process for separating ethane using catalytic dry gas adsorption according to claim 1, characterized in that, The specific steps of the preprocessing in S1 are as follows: S11: Dry gas is introduced into the pressure swing adsorption unit to adsorb methane; S12: Then it is sent to the compression unit to remove heavy hydrocarbons from the dry gas; S13: Then, after passing through the desulfurization and decarbonization unit, H2S in the dry gas is absorbed by MDEA, CO2 is absorbed by NaOH solution, and then H2S is removed to a content ≤0.1μg / g by the fine desulfurization unit; S14: After deoxygenation by a deaerator, the gas is cooled to 40°C to separate water, and then pretreated dry gas is obtained after alkaline washing.

3. The process for separating ethane using catalytic dry gas adsorption according to claim 1, characterized in that, The drying temperature in S21 is 120℃ and the drying time is 4-6 hours.

4. The process for separating ethane using catalytic dry gas adsorption according to claim 1, characterized in that, The sieve used for sieving CuCl in S22 is 300-400 mesh.

5. The process for separating ethane using catalytic dry gas adsorption according to claim 1, characterized in that, The heating rate in S23 is 5℃ / min, and the calcination time is 4-6h.

6. The process for separating ethane using catalytic dry gas adsorption according to claim 1, characterized in that, The pressure condition in S3 is 3.0-4.0 MPa.

7. The process for separating ethane using catalytic dry gas adsorption according to claim 1, characterized in that, The temperature of the cooled dry gas in S3 is 10-15℃.

8. The process for separating ethane using catalytic dry gas adsorption according to claim 1, characterized in that, The adsorption temperature in S4 is 25-60℃, and the dry gas flow rate is 25-60L / min.

9. The process for separating ethane using catalytic dry gas adsorption according to claim 1, characterized in that, The condition for adsorption to reach saturation in S4 is that the outlet gas concentration of C2H6 / C2H4 is the same as the inlet gas concentration.