Process for separating carbon dioxide components

Abstract

The present application relates to the field of refinery dry gas treatment, and discloses a method for separating carbon two components. The method comprises the following steps: (1) sequentially performing acid gas removal, oxygen removal and gas-liquid cutting on refinery dry gas to obtain a first gas phase and a first liquid phase; (2) performing condensate stripping on the first liquid phase to obtain a stripping gas phase and a stripping liquid phase; (3) returning the stripping gas phase to the above treatment together with the refinery dry gas; and (4) feeding the first gas phase into a cryogenic absorption tower to obtain a cryogenic tower top gas phase and a cryogenic tower bottom liquid phase. The method can fully separate and recover ethylene and ethane in the refinery dry gas, and has high recovery rate and low energy consumption.

Description

Technical Field

[0001] This invention relates to the field of refinery dry gas treatment, and more specifically to a method for separating C2 components. Background Technology

[0002] Refinery dry gas primarily originates from the secondary processing of crude oil. Currently, most refineries still burn it as fuel gas, resulting in low utilization value and significant resource waste and environmental pollution. Refinery dry gas mainly includes saturated and unsaturated dry gas. Unsaturated dry gas contains ethylene, propylene, etc., while saturated dry gas mainly contains alkanes. Separating and recovering hydrocarbons from refinery dry gas, especially important chemical feedstocks like ethylene and ethane, could significantly improve its utilization value. However, current separation processes suffer from drawbacks such as high energy consumption and low recovery rates, and some equipment may experience heavy loads during operation.

[0003] Therefore, there is an urgent need to develop a process that can fully recover the target gas from refinery dry gas, with a high recovery rate and low energy consumption. Summary of the Invention

[0004] The purpose of this invention is to overcome the aforementioned problems in the prior art and provide a method for separating C2 components. This method can fully separate and recover ethylene and ethane from refinery dry gas, and has a high recovery rate and low energy consumption.

[0005] To achieve the above objectives, the present invention provides a method for separating C2 components, the method comprising:

[0006] (1) The refinery dry gas is subjected to acid gas removal, oxygen removal and gas-liquid cutting in sequence to obtain the first gas phase and the first liquid phase;

[0007] (2) The first liquid phase is subjected to condensate stripping to obtain stripping gas phase and stripping liquid phase;

[0008] (3) The stripped gas phase is returned to the refinery dry gas for the above processing;

[0009] (4) The first gas phase is fed into the cryogenic absorption tower to obtain the top gas phase and the bottom liquid phase of the cryogenic tower;

[0010] (5) Optionally, the cold energy of the gas phase at the top of the cryogenic tower is recovered.

[0011] Through the above technical solution, the present invention can fully separate and recover ethylene and ethane from refinery dry gas, with a high recovery rate and low energy consumption. Attached Figure Description

[0012] Figure 1This is a process flow diagram for separating C2 components provided by a preferred embodiment of the present invention.

[0013] Explanation of reference numerals in the attached figures

[0014] 1-Compressor; 2-Amine washing tower; 3-Inorganic alkali washing tower; 4-Deoxygenation reactor; 5-Cooler; 6-Gas-liquid cutting tank; 7-Condensate stripping tower; 8-Gas phase dryer; 9-Cold box; 10-Cryogenic absorption tower; 11-Refinery dry gas; 12-Cryogenic absorbent; 13-Cryogenic tower bottom liquid phase; 14-Cryogenic tower top gas phase; 15-Light hydrocarbon products. Detailed Implementation

[0015] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0016] This invention provides a method for processing and separating C2 components, the method comprising:

[0017] (1) The refinery dry gas is subjected to acid gas removal, oxygen removal and gas-liquid cutting in sequence to obtain the first gas phase and the first liquid phase;

[0018] (2) The first liquid phase is subjected to condensate stripping to obtain stripping gas phase and stripping liquid phase;

[0019] (3) The stripped gas phase is returned to the refinery dry gas for the above processing;

[0020] (4) The first gas phase is fed into the cryogenic absorption tower to obtain the top gas phase and the bottom liquid phase of the cryogenic tower;

[0021] (5) Optionally, the cold energy of the gas phase at the top of the cryogenic tower is recovered.

[0022] In addition to hydrocarbon gases, refinery dry gas also contains some acidic gases such as carbon dioxide and hydrogen sulfide, as well as some oxygen and water. Therefore, it is necessary to remove acidic gases and oxygen. It is understood that the C2 component refers to ethylene and / or ethane.

[0023] Using the scheme of this invention, different components are separated in a cryogenic absorption tower at a relatively low temperature (i.e., cryogenic). The C2 component mainly enters the cryogenic tower bottom liquid phase, resulting in a high recovery rate. Downstream processes can further separate the cryogenic tower bottom liquid phase as needed. In the chemical industry, "standard oil" is commonly used to measure energy consumption; one kilogram of standard oil is approximately 10,000 kcal.

[0024] According to the present invention, preferably, before removing acidic gases, the method further includes: adjusting the refinery dry gas pressure to 1-3.8 MPa (e.g., 1 MPa, 1.1 MPa, 1.2 MPa, 1.3 MPa, 1.4 MPa, 1.5 MPa, 1.6 MPa, 1.7 MPa, 1.8 MPa, 1.9 MPa, 2 MPa, 2.1 MPa, 2.2 MPa, 2.3 MPa, 2.4 MPa, 2.5 MPa, 2...). The pressure and temperature of the dry gas obtained from the refinery may fall outside the above ranges (e.g., 0.8 MPa, 3 MPa, 3.2 MPa, 3.4 MPa, 3.6 MPa, 3.8 MPa, and any two of the above values), and the temperature should be adjusted to 25-65°C (e.g., 25°C, 30°C, 32°C, 34°C, 36°C, 38°C, 40°C, 42°C, 44°C, 46°C, 48°C, 50°C, 55°C, 60°C, 65°C, and any two of the above values). It is understood that the pressure and temperature of the dry gas obtained from the refinery may not be within the above ranges; therefore, the pressure and temperature can be adjusted before acid gas removal. The pressure of the refinery dry gas is increased to the above range using a compressor, and a cooler can be installed at the compressor outlet to adjust the temperature to the above range. Meeting the above ranges allows for better removal of acid gases.

[0025] According to the present invention, preferably, the method for removing acidic gases includes: alkaline washing of refinery dry gas.

[0026] According to the present invention, preferably, the alkaline washing method includes: washing the refinery dry gas with organic amines and inorganic alkalis.

[0027] According to the present invention, preferably, the conditions for the organic amine washing include: the eluent is an organic amine solution, and the mass concentration of the organic amine in the organic amine solution is 28-35 wt%. The amine washing can be carried out in an amine washing tower.

[0028] According to the present invention, preferably, the organic amine is methyldiethanolamine.

[0029] According to the present invention, preferably, the conditions for the inorganic alkaline washing include: the eluent is an alkali metal hydroxide solution, and the mass concentration of the alkali metal hydroxide in the alkali metal hydroxide solution is 8-16 wt%. The inorganic alkaline washing can be carried out in an inorganic alkaline washing tower. The alkali metal hydroxide is preferably sodium hydroxide.

[0030] When the above conditions are met, it can be further ensured that acidic gases are removed from the refinery dry gas.

[0031] The gas can be pressurized after alkaline washing and before deoxidation, depending on the pressure required for cryogenic absorption. If the gas pressure before deoxidation has already reached the pressure required for cryogenic absorption, then pressurization is not necessary.

[0032] According to the present invention, preferably, the oxygen removal conditions include: a temperature of 40-400℃ (for example, 40℃, 50℃, 60℃, 80℃, 100℃, 130℃, 150℃, 170℃, 200℃, 220℃, 250℃, 270℃, 300℃, 320℃, 340℃, 360℃, 380℃, 400℃, and values ​​within any two of the above values), and a pressure of 1-5.5. MPa (e.g., 1 MPa, 1.2 MPa, 1.3 MPa, 1.4 MPa, 1.5 MPa, 1.7 MPa, 2 MPa, 2.3 MPa, 2.5 MPa, 2.7 MPa, 3 MPa, 3.3 MPa, 3.5 MPa, 3.7 MPa, 4 MPa, 4.3 MPa, 4.5 MPa, 5 MPa, 5.5 MPa, and values ​​within any two of the above values). Deoxygenation can be carried out in a deoxygenation reactor. The deoxygenation catalyst can be any conventional choice in the art, and will not be elaborated here. Temperature can be adjusted to the preferred range described above using a heater.

[0033] According to the present invention, preferably, before performing gas-liquid cutting, the method further includes: pre-cooling the material to a material temperature of 4-35°C (for example, 4°C, 5°C, 7°C, 10°C, 12°C, 15°C, 17°C, 20°C, 23°C, 25°C, 28°C, 30°C, 32°C, 34°C, 35°C, and any two of the above values, or values ​​within the range).

[0034] According to the present invention, the preferred conditions for condensate stripping include: being carried out in a condensate stripping tower with a theoretical plate number of 10-20 (e.g., 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20), an operating pressure of 0.5-3.5 MPa (0.5 MPa, 1 MPa, 1.5 MPa, 2 MPa, 2.5 MPa, 3 MPa, 3.2 MPa, 3.5 MPa), a tower top temperature of 10-60°C (e.g., 10°C, 20°C, 30°C, 40°C, 50°C, 60°C), and a tower bottom temperature of 60-150°C (60°C, 70°C, 80°C, 90°C, 100°C, 110°C, 120°C, 130°C, 140°C, 150°C). After condensate stripping, the heavy components (mainly C3 and above) in the first liquid phase enter the stripping liquid phase, which can be directly sent out of the unit as a light hydrocarbon product, thereby reducing the load on subsequent equipment.

[0035] According to the present invention, preferably, before the first gas phase is fed into the cryogenic absorption tower, the method further includes: sequentially subjecting the first gas phase to gas phase drying and a first cooling; wherein the gas phase drying results in a water content in the material ≤ 2 ppm by volume, and the first cooling results in a temperature of -70°C to -110°C (for example, it can be -70°C, -75°C, -80°C, -85°C, -90°C, -95°C, -100°C, -115°C, -110°C, or any two of the above values ​​within a range). The first cooling can be carried out in a cold box. The refrigerant in the cold box can be multi-temperature propylene and ethylene (as the refrigerant in a multi-stage cooling cold box).

[0036] According to the present invention, preferably, no condenser is installed in the cryogenic absorption tower.

[0037] According to the present invention, the preferred operating conditions in the cryogenic absorption tower include: operation in the presence of a cryogenic absorbent; a theoretical plate number preferably of 20-70 (e.g., a range or value within the range of 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, or any two of the above values); and an operating pressure preferably of 0.5-6.4 MPa (e.g., a range of 0.5 MPa, 1 MPa, 1.5 MPa, 2 MPa, 2.5 MPa, 3 MPa, 3.5 MPa, 4 MPa, 5 MPa, 5.5 MPa, 6 MPa, 6.4 MPa, or any two of the above values). The column top temperature is preferably -55℃ to -118℃ (e.g., -55℃, -60℃, -65℃, -70℃, -75℃, -80℃, -85℃, -90℃, -95℃, -100℃, -105℃, -110℃, -118℃, and any two of the above values), and the column bottom temperature is preferably -28℃ to 58℃ (e.g., -28℃, -30℃, -20℃, -10℃, 0℃, 10℃, 20℃, 30℃, 40℃, 50℃, 58℃, and any two of the above values). The presence of the cryogenic absorbent allows for the further absorption of components other than methane hydrogen present in the upper part of the column without the need for a condenser, reducing cooling consumption and saving on condenser investment and energy consumption. The cryogenic absorbent introduced from the outside can be cooled to -70°C to -120°C in a cold box before being introduced into the cryogenic absorption tower. The mass of the cryogenic absorbent used per unit time can be maintained at 0.03-0.4 times the total mass of the first gas and first liquid phases introduced into the cryogenic absorption tower.

[0038] According to the present invention, preferably, the method for recovering cold energy includes: using the cryogenic tower overhead gas phase as at least a portion of the refrigerant for the first cooling. The cryogenic tower overhead gas phase can be introduced into the cold box used for the first cooling as at least a portion of the refrigerant, thus enabling sufficient recovery of the cold energy in the cryogenic tower overhead gas phase.

[0039] The present invention will be described in detail below through embodiments.

[0040] Examples 1-3 describe methods for separating C2 components, in the following ways: Figure 1 The process is carried out in the equipment shown. Figure 1 In the diagram, 1 is the compressor; 2 is the amine washing tower; 3 is the inorganic alkali washing tower; 4 is the deoxygenation reactor; 5 is the cooler; 6 is the gas-liquid cutting tank; 7 is the condensate stripping tower; 8 is the gas phase dryer; 9 is the cold box; 10 is the cryogenic absorption tower; 11 is the refinery dry gas; 12 is the cryogenic absorbent; 13 is the cryogenic tower bottom liquid phase; 14 is the cryogenic tower top gas phase; and 15 is the light hydrocarbon product.

[0041] According to the material flow, amine washing tower 2, inorganic alkaline washing tower 3, deoxygenation reactor 4, and cooler 5 are connected sequentially via pipelines. Compressors 1 are installed before amine washing tower 2 and after inorganic alkaline washing tower 3 (the compressor outlet before amine washing tower 2 also has a cooler, and the compressor outlet after inorganic alkaline washing tower 3 has a heater, neither shown in the diagram). The compressor 1 after alkaline washing tower 3 can be turned on or off as needed to achieve the required pressure. The connection between gas-liquid separator 6, condensate stripping tower 7, and gas phase dryer 8 allows the gas phase separated by gas-liquid separator 6 to enter gas phase dryer 8, and the resulting liquid phase to enter condensate stripping tower 7. Condensate stripping tower 7 is connected to compressor 1 before amine washing tower 2, so that the stripped gas phase separated by condensate stripping tower 7 can be returned to the refinery dry gas for further pressurization and other processing. The stripped liquid phase obtained from condensate stripping tower 7 is led out as light hydrocarbon product 15 via pipeline. A gas-phase dryer 8, a cold box 9, and a cryogenic absorption tower 10 are connected in sequence. Material from the gas-phase dryer 8 is cooled by the cold box 9 and then enters the cryogenic absorption tower 10 from the upper middle part. The top of the cryogenic absorption tower 10 is connected to the cold box 9 via a pipe, allowing the gas phase at the top of the tower to flow back into the cold box 9 as a refrigerant before being drawn out. The liquid phase obtained from the bottom of the cryogenic absorption tower 10 is drawn out via a pipe. Furthermore, the piping arrangement ensures that the cryogenic absorbent 12 introduced from the outside first passes through the cold box 9 before being introduced into the cryogenic absorption tower. The refrigerant in the cold box 9 is a multi-temperature propylene refrigerant and an ethylene refrigerant.

[0042] Example 1

[0043] The composition and mass flow rate of the saturated refinery dry gas 11 used in this embodiment, as well as the composition and mass flow rate of the introduced cryogenic absorbent 12, are shown in Table 1.

[0044] Table 1

[0045] Refinery dry gas 11 Cryogenic Absorbent 12 Mass flow rate (kg / hr) 142719 8000 Molar composition (%) hydrogen 38.03 0 Nitrogen 4.16 0 oxygen 0.06 0 carbon monoxide 0.29 0 carbon dioxide 2.56 0 methane 25.03 0 Ethane 17.42 0.21 propane 6.44 67.38 Isobutane 2.14 21.97 n-Butane 1.06 10.44 pentane 0.94 0 hexane 0.33 0 water 1.55 0

[0046] The specific method for separating the C2 components is as follows:

[0047] (1) Refinery dry gas 11 (pressure 0.5 MPa) is introduced into compressor 1 to increase the pressure to 2 MPa, and then cooled to 40°C by the cooler at the outlet of compressor 1. It is then sent to amine washing tower 2 (the eluent is an aqueous solution of methyl diethanolamine with a concentration of 35% by mass) for organic amine washing. The material after organic amine washing is then sent to inorganic alkali washing tower 3 (the eluent is an aqueous solution of sodium hydroxide with a concentration of 8% by mass) for inorganic alkali washing.

[0048] After being washed with inorganic alkali, the material is increased to 4.0 MPa by compressor 1 and heated to 150°C by heater before being introduced into deoxygenation reactor 4 (where the deoxygenation catalyst is a nickel-based catalyst) for oxygen removal.

[0049] The deoxygenated material is introduced into cooler 5 and pre-cooled to 15°C before being sent to gas-liquid cutting tank 6 for gas-liquid cutting to obtain the first gas phase and the first liquid phase.

[0050] (2) The first liquid phase is fed into the condensate stripping tower 7, which has a theoretical plate number of 15, an operating pressure of 1.8 MPa, a top temperature of 45°C, and a bottom temperature of 110°C. The stripped liquid phase is separated and taken out of the device as light hydrocarbon product 15; the stripped gas phase is returned to the compressor 1 before the amine washing tower 2.

[0051] The first gas phase is dried in the gas phase dryer 8 until the water content in the material is ≤2 ppm by volume; then it is cooled to -100℃ in the cold box 9.

[0052] The first gas phase is then fed into a cryogenic absorption tower, which does not have a condenser. The cryogenic absorption tower has a theoretical plate count of 50, an operating pressure of 3 MPa, a top temperature of -90°C, and a bottom temperature of 45°C. The cryogenic absorbent 12 is cooled to -80°C in a cold box before being fed to the top of the tower. The liquid phase 13 at the bottom of the cryogenic tower is piped out, and the gas phase 14 at the top of the cryogenic tower is led out after heat recovery in the cold box 9.

[0053] The discharge flow rates and compositions of the cryogenic tower bottom liquid phase 13, the cryogenic tower top gas phase 14, and the light hydrocarbon product 15 are shown in Table 2.

[0054] Table 2

[0055]

[0056]

[0057] In the cryogenic tower bottom liquid phase 13, the C2 recovery rate is greater than 99.3%. The energy consumption is 62 kg standard oil / t feed (feed refers to the refinery dry gas entering the unit).

[0058] Example 2

[0059] The composition of the unsaturated refinery dry gas 11 used in this embodiment and the mass flow rate of the introduction device, as well as the composition of the introduced cryogenic absorbent 12 and the mass flow rate of the introduction device, are shown in Table 3.

[0060] Table 3

[0061] Refinery dry gas 11 Cryogenic Absorbent 12 Mass flow rate (kg / hr) 139538 40000 Molar composition (%) hydrogen 35.66 0 Nitrogen 5.16 0 oxygen 0.87 0 carbon monoxide 0.29 0 carbon dioxide 2.54 0 methane 24.87 0 ethylene 10.21 0 Ethane 9.24 0.27 propylene 2.15 35.12 propane 4.06 64.01 Isobutane 2.13 0.59 n-Butane 1.05 0.01 pentane 0.94 0 hexane 0.33 0 water 0.50 0

[0062] The specific method for separating the C2 components is as follows:

[0063] (1) Refinery dry gas 11 (pressure 0.6 MPa) is introduced into compressor 1 to increase the pressure to 2.2 MPa, and then cooled to 45°C by the cooler at the outlet of compressor 1. It is then sent to amine washing tower 2 (the eluent is an aqueous solution of methyl diethanolamine with a concentration of 32% by mass) for organic amine washing. The material after organic amine washing is then sent to inorganic alkaline washing tower 3 (the eluent is an aqueous solution of sodium hydroxide with a concentration of 14% by mass) for inorganic alkaline washing.

[0064] After the inorganic alkaline washing material is heated to 130°C by a heater, it is introduced into deoxygenation reactor 4 (where the deoxygenation catalyst is a nickel-based catalyst) for oxygen removal.

[0065] The deoxygenated material is introduced into cooler 5 and pre-cooled to 20°C before being sent to gas-liquid cutting tank 6 for gas-liquid cutting to obtain the first gas phase and the first liquid phase.

[0066] (2) The first liquid phase is fed into the condensate stripping tower 7, which has a theoretical plate number of 18, an operating pressure of 1.0 MPa, a top temperature of 30°C, and a bottom temperature of 101°C. The stripped liquid phase is taken out of the device and can be used as light hydrocarbon product 15; the stripped gas phase is returned to the compressor 1 before the amine washing tower 2.

[0067] The first gas phase is dried in the gas phase dryer 8 until the water content in the material is ≤2 ppm by volume; then it is cooled in the cold box 9 to a temperature of -99°C.

[0068] The first gas phase is then fed into a cryogenic absorption tower, which does not have a condenser. The cryogenic absorption tower has a theoretical plate number of 55, an operating pressure of 1.3 MPa, a top temperature of -75°C, and a bottom temperature of 21°C. The cryogenic absorbent 12 is cooled to -95°C in a cold box before being fed to the top of the tower. The liquid phase 13 at the bottom of the cryogenic tower is piped out, and the gas phase 14 at the top of the cryogenic tower is led out after heat recovery in the cold box 9.

[0069] The discharge flow rates and compositions of the cryogenic tower bottom liquid phase 13, the cryogenic tower top gas phase 14, and the light hydrocarbon product 15 are shown in Table 4.

[0070] Table 4

[0071]

[0072]

[0073] In the cryogenic tower bottom liquid phase 13, the C2 recovery rate is greater than 98.5%. The energy consumption is 64 kg standard oil / t feed.

[0074] Example 3

[0075] The composition of the unsaturated refinery dry gas 11 used in this embodiment and the mass flow rate of the introduction device, as well as the composition of the introduced cryogenic absorbent 12 and the mass flow rate of the introduction device, are shown in Table 5.

[0076] Table 5

[0077] Refinery dry gas 11 Cryogenic Absorbent 12 Mass flow rate (kg / hr) 139538 55000 Molar composition (%) hydrogen 35.66 0 Nitrogen 5.16 0 oxygen 0.87 0 carbon monoxide 0.29 0 carbon dioxide 2.54 0 methane 24.87 0 ethylene 10.21 0 Ethane 9.24 0.21 propylene 2.15 19.46 propane 4.06 43.57 Isobutane 2.13 24.74 n-Butane 1.05 12.02 pentane 0.94 0 hexane 0.33 0 water 0.50 0

[0078] The specific method for separating the C2 components is as follows:

[0079] (1) Refinery dry gas 11 (pressure 0.7 MPa) is introduced into compressor 1 to increase the pressure to 1.2 MPa, and then cooled to 45°C by the cooler at the outlet of compressor 1. It is then sent to amine washing tower 2 (eluent is an aqueous solution of methyl diethanolamine with a concentration of 28% by mass) for organic amine washing. The material after organic amine washing is then sent to inorganic alkali washing tower 3 (eluent is an aqueous solution of sodium hydroxide with a concentration of 16% by mass) for inorganic alkali washing.

[0080] After the inorganic alkaline washing material is heated to 130°C by a heater, it is introduced into deoxygenation reactor 4 (where the deoxygenation catalyst is a nickel-based catalyst) for oxygen removal.

[0081] The deoxygenated material is introduced into cooler 5 and pre-cooled to 20°C before being sent to gas-liquid cutting tank 6 for gas-liquid cutting to obtain the first gas phase and the first liquid phase.

[0082] (2) The first liquid phase is fed into the condensate stripping tower 7, which has a theoretical plate number of 17, an operating pressure of 1.1 MPa, a top temperature of 32°C, and a bottom temperature of 111°C. The stripped liquid phase is taken out of the device and can be used as light hydrocarbon product 15; the stripped gas phase is returned to the compressor 1 before the amine washing tower 2.

[0083] The first gas phase is dried in the gas phase dryer 8 until the water content in the material is ≤2 ppm by volume; then it is cooled in the cold box 9 to a temperature of -98℃.

[0084] The first gas phase is then fed into a cryogenic absorption tower, which does not have a condenser. The cryogenic absorption tower has a theoretical plate number of 57, an operating pressure of 0.6 MPa, a top temperature of -80°C, and a bottom temperature of -20°C. The cryogenic absorbent 12 is cooled to -115°C in a cold box before being fed to the top of the tower. The liquid phase 13 at the bottom of the cryogenic tower is piped out, and the gas phase 14 at the top of the cryogenic tower is led out after heat recovery in the cold box 9.

[0085] The discharge flow rates and compositions of the cryogenic tower bottom liquid phase 13, the cryogenic tower top gas phase 14, and the light hydrocarbon product 15 are shown in Table 6.

[0086] Table 6

[0087]

[0088]

[0089] In the cryogenic tower bottom liquid phase 13, the C2 recovery rate is greater than 96.3%. The energy consumption is 63 kg standard oil / t feed.

[0090] Comparative Example 1

[0091] The refinery dry gas and method of Example 1 are separated, except that the cryogenic absorbent 12 is not introduced into the cryogenic absorber.

[0092] The discharge flow rates and compositions of the cryogenic tower bottom liquid phase 13, the cryogenic tower top gas phase 14, and the light hydrocarbon product 15 are shown in Table 7.

[0093] Table 7

[0094]

[0095]

[0096] In the cryogenic tower bottom liquid phase 13, the C2 recovery rate is approximately 89%.

[0097] As can be seen from the above, the technical solution of the present invention has a high C2 recovery rate and the energy consumption is generally below 100 kg of standard oil / t of raw material, which is low.

[0098] The preferred embodiments of the present invention have been described in detail above; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combinations of various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.

Claims

1. A method for separating carbon-2 components, characterized in that, The method includes: (1) The refinery dry gas is subjected to acid gas removal, oxygen removal and gas-liquid cutting in sequence to obtain the first gas phase and the first liquid phase; (2) The first liquid phase is subjected to condensate stripping to obtain stripping gas phase and stripping liquid phase; (3) The stripped gas phase is returned to the refinery dry gas for the above treatment; (4) The first gas phase is fed into the cryogenic absorption tower. No condenser is installed in the cryogenic absorption tower. The process is carried out in the presence of the cryogenic absorbent to obtain the top gas phase and the bottom liquid phase of the cryogenic tower. Before the first gas phase is fed into the cryogenic absorption tower, the method further includes: sequentially performing gas phase drying and first cooling on the first gas phase; the gas phase drying makes the water content in the material ≤2 ppm by volume, and the first cooling makes the temperature -70℃ to -110℃. The operating conditions in the cryogenic absorption tower include: a tower top temperature of -55°C to -118°C; (5) Optionally, the cold energy of the gas phase at the top of the cryogenic tower is recovered.

2. The method according to claim 1, wherein, Before removing acidic gases, the method also includes adjusting the refinery dry gas pressure to 1-3.8 MPa and the temperature to 25-65°C.

3. The method according to claim 1, wherein, The method for removing acidic gases includes: alkaline washing of refinery dry gas.

4. The method according to claim 3, wherein, The alkaline washing method includes: washing refinery dry gas with organic amines and inorganic alkalis.

5. The method according to claim 4, wherein, The conditions for the organic amine washing include: the eluent is an organic amine solution, and the mass concentration of organic amine in the organic amine solution is 28-35 wt%.

6. The method according to claim 5, wherein, The organic amine is methyldiethanolamine.

7. The method according to claim 4, wherein, The conditions for the inorganic alkaline washing include: the eluent is an alkali metal hydroxide solution, and the mass concentration of the alkali metal hydroxide in the alkali metal hydroxide solution is 8-16 wt%.

8. The method according to claim 1 or 3, wherein, The conditions for oxygen removal include a temperature of 40-400℃ and a pressure of 1-5.5MPa.

9. The method according to claim 1 or 4, wherein, Before performing gas-liquid cutting, the method also includes pre-cooling the material to a temperature of 4-35°C.

10. The method according to claim 1 or 2, wherein, The conditions for condensate stripping include: it is carried out in a condensate stripping tower with a theoretical plate number of 10-20, an operating pressure of 0.5-3.5 MPa, a top temperature of 10-60℃, and a bottom temperature of 60-150℃.

11. The method according to claim 1 or 4, wherein, The operating conditions in a cryogenic absorption tower include: 20-70 theoretical plates, 0.5-6.4 MPa operating pressure, and bottom temperature of -28℃ to 58℃.

12. The method according to claim 9, wherein, The method for recovering cold energy includes using the top gas phase of the cryogenic tower as at least a portion of the refrigerant for the first cooling.

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