CN113354506B - Method for recovering and separating low-carbon hydrocarbons from refinery saturated dry gas by combined absorption - Google Patents
Method for recovering and separating low-carbon hydrocarbons from refinery saturated dry gas by combined absorption Download PDFInfo
- Publication number
- CN113354506B CN113354506B CN202110293757.4A CN202110293757A CN113354506B CN 113354506 B CN113354506 B CN 113354506B CN 202110293757 A CN202110293757 A CN 202110293757A CN 113354506 B CN113354506 B CN 113354506B
- Authority
- CN
- China
- Prior art keywords
- tower
- absorption
- dry gas
- propane
- refinery
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Active
Links
Images
Classifications
-
- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C7/00—Purification; Separation; Use of additives
- C07C7/11—Purification; Separation; Use of additives by absorption, i.e. purification or separation of gaseous hydrocarbons with the aid of liquids
-
- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C7/00—Purification; Separation; Use of additives
-
- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C7/00—Purification; Separation; Use of additives
- C07C7/04—Purification; Separation; Use of additives by distillation
Abstract
The invention provides a method for combined absorption, recovery and separation of low-carbon hydrocarbons in saturated dry gas of a refinery, which comprises the following steps: s1, gradually compressing saturated dry gas of a refinery to 3-4.5 MPag through a gas compressor, removing impurities through an impurity removal device, gradually cooling the gas to-15 to-35 ℃ through a cooler, and allowing the gas to enter an absorption tower; s2, liquid-phase propane or a C3 fraction rich in propane is adopted as an absorbent in the absorption tower, and the absorbent enters the absorption tower from the top of the tower to absorb components of C2 and above C2 in saturated dry gas; feeding the tower bottom material of the absorption tower to a desorption tower, and feeding the tower top gas phase of the absorption tower into a reabsorption tower; the invention takes propane or C3 fraction rich in propane as an absorbent, takes toluene or xylene and industrial hexane as a reabsorber, and absorbs and separates saturated dry gas produced by each device of a refinery under the condition of intercooling, the recovery rates of ethane and propane can reach more than 98 percent, meanwhile, the circulation amount and the loss amount of the absorbent are relatively small, the absorbent does not need to be supplemented basically, and the energy consumption of the device is low.
Description
Technical Field
The invention relates to a method for separating low-carbon hydrocarbons from saturated dry gas in a refinery, in particular to a method for separating low-carbon hydrocarbons from saturated dry gas in a refinery by combined absorption and recovery.
Background
The saturated dry gas of the refinery is mainly from primary processing and secondary processing of crude oil, such as by-product gas in the processes of atmospheric and vacuum distillation, hydrocracking, reforming and the like, and mainly comprises components such as hydrogen, methane, ethane, propane and the like. At present, most of the saturated dry gas of refineries is directly used as industrial or civil fuel, which causes serious waste of resources. Ethane and propane can be used as raw materials of an ethylene cracking device for producing ethylene and propylene, so that the cost of ethylene cracking raw materials can be effectively reduced, and the economic benefit of enterprises is improved.
At present, the separation method of saturated dry gas in a refinery mainly comprises a cryogenic separation method, an intermediate cooling oil absorption method, a pressure swing adsorption method, a shallow cooling oil absorption method and the like, and various methods have respective characteristics. The cryogenic separation method has high recovery rate and mature process, but has large equipment investment and higher energy consumption; the intercooled oil absorption method mostly adopts mixed carbon four or carbon five as an absorbent, so that the investment is low, the adaptability is strong, but the recovery rate is low, the circulation amount and loss of the absorbent are large, and the energy consumption is high; the pressure swing adsorption has low energy consumption, simple operation, large occupied area, poor absorption effect, low product purity and low recovery rate.
Patent publication No. CN106609161A proposes a method for separating saturated dry gas of a refinery, which adopts C4 as an absorbent, C2 fraction and heavier components in the compressed and cooled saturated dry gas are absorbed in a main absorption tower, a bottom material flow of the main absorption tower is sent to a desorption tower, and recovered C2 concentrated gas is obtained at the top of the desorption tower. The pressure of the absorption tower is about 3.0-4.5 MPag, the temperature of the top of the absorption tower is about 5-25 ℃, and the temperature of the bottom of the absorption tower is 100-160 ℃. The temperature of the top of the desorption tower is 55-65 ℃, and the temperature of the bottom of the desorption tower is 100-160 ℃. The method is provided with a reabsorption tower and a stabilization tower, wherein stabilized gasoline is used as an absorbent to absorb a C4 absorbent carried out from gas at the top of a main absorption tower, rich absorption oil enters the stabilization tower, the temperature at the top of the stabilization tower is 40-80 ℃, and the temperature at the bottom of the stabilization tower is 150-200 ℃. The recovery rate of C2 is about 97%, the total recovery rate of C2 and C3 is about 94%, but the circulating amount and loss amount of the absorbent are large, the temperatures of the bottoms of the absorption tower, the desorption tower and the stabilization tower are high, the energy consumption is relatively high, and heavy components are carried in dry gas (the dry gas is not dry).
The patent publication No. CN104560194A proposes a saturated dry gas recovery system and recovery method of a refinery, the method adopts carbon four or carbon five as an absorbent, a condensate stripping tower is arranged, condensate between sections of a compressor is sent to the condensate stripping tower, and a product after stripping is directly sent to an ethylene device cracking furnace. The method is additionally provided with a reabsorption tower, and the reabsorption agent is gasoline. The total recovery rate of C2 and C3 in the method is about 96%, but the circulating amount and the loss amount of the absorbent are large, the temperatures of the bottoms of the absorption tower and the desorption tower are high, and the energy consumption is high.
Patent publication No. CN109553504A proposes a method and a device for recovering refinery saturated dry gas by adopting a shallow cold oil absorption technology, wherein C4 is adopted as an absorbent, the temperature of the top of an absorption tower is about 5-25 ℃, and the temperature of the bottom of the absorption tower is 100-160 ℃. The temperature of the top of the desorption tower is 55-65 ℃, the temperature of the bottom of the desorption tower is 100-160 ℃, most of the liquid phase at the bottom of the desorption tower is used as a circulating absorbent to return to the absorption tower, and the small part of the liquid phase is sent to a gasoline stabilizing tower for treatment. The reabsorption tower adopts stable gasoline as an absorbent to absorb the C4 absorbent carried out from the gas at the top of the main absorption tower, and rich absorption oil enters the stabilization tower, wherein the temperature at the top of the stabilization tower is 40-80 ℃, and the temperature at the bottom of the stabilization tower is 120-150 ℃. The recovery rate of C2 is about 98%, the total recovery rate of C2 and C3 is about 95%, but the circulating amount and loss amount of the absorbent are large, the temperatures of the bottoms of the absorption tower, the desorption tower and the stabilizing tower are high, and the energy consumption is relatively high.
In summary, the current refinery gas recycling mainly aims at catalytic dry gas, and the recycling of saturated dry gas is less studied. The existing process for separating C2/C3 from saturated dry gas has the problems of high energy consumption, large scale of a tower and other equipment, large investment, low C2/C3 recovery rate, dry gas non-drying and the like.
Disclosure of Invention
The invention aims to provide a method for combined absorption, recovery and separation of low carbon hydrocarbons in saturated dry gas of a refinery, so as to solve the problems in the background technology.
In order to achieve the purpose, the invention provides the following technical scheme:
a method for combined absorption, recovery and separation of low-carbon hydrocarbons in saturated dry gas of a refinery comprises the following steps:
s1, gradually compressing saturated dry gas of a refinery to 3-4.5 MPag by a gas compressor, removing impurities by an impurity removing device, and gradually cooling the saturated dry gas to-15 to-35 ℃ by a cooler to enter an absorption tower;
s2, liquid-phase propane or a C3 fraction rich in propane is adopted as an absorbent in the absorption tower, and the absorbent enters the absorption tower from the top of the tower to absorb components of C2 and above C2 in saturated dry gas; the tower bottom material of the absorption tower is sent to a desorption tower, and the tower top gas phase of the absorption tower enters a reabsorption tower;
s3, adopting liquid-phase methylbenzene or dimethylbenzene and industrial hexane as a reabsorber by the reabsorption tower to absorb C2 and C3 components carried out by the gas at the top of the absorption tower, taking the gas at the top of the reabsorption tower as dry gas, merging the gas into a fuel gas pipe network, and sending the liquid phase at the bottom of the reabsorption tower into a reabsorption tower;
s4, condensing the gas phase at the top of the re-desorption tower, returning the condensed liquid rich in propane to the absorption tower after pressurizing and cooling by a pump, and returning the liquid phase at the bottom of the re-desorption tower serving as a re-absorbent to the top of the re-absorption tower through cooling circulation;
s5, obtaining an ethane and propane mixed component at the top of the desorption tower; a part of the C3+ liquid phase at the bottom of the desorption tower is pressurized and cooled and then circularly returned to the absorption tower, and the rest part enters a depropanizing tower to be continuously separated and continuously separated;
s6, separating the top of the depropanizing tower to obtain high-purity propane, mixing one part of the high-purity propane serving as a circulating absorbent with a circulating material at the bottom of the desorption tower after pressurizing and cooling, returning the mixture to the absorption tower, and discharging the other part of the high-purity propane serving as a propane product discharge device; c4+ liquid phase obtained at the bottom of the depropanizing tower is sent to a subsequent device for treatment.
As a further scheme of the invention: in the step S1, the saturated dry gas of the refinery is compressed step by 3-4 sections; the impurity removal process comprises amine washing, alkali washing and drying.
As a further scheme of the invention: the absorption tower has 20-70 layers of theoretical plates, 10-40 layers of feeding positions, 3-4.5 MPag pressure at the top of the tower, -35-10 ℃ temperature at the top of the tower, 60-90 ℃ temperature at the bottom of the tower, and a plurality of middle-section reflux arranged in the absorption tower.
As a further scheme of the invention: the reabsorption tower has 15-70 layers of theoretical plates, 5-40 layers of feeding positions, tower top pressure of 1.5-2.5 MPag, tower top temperature of 0-15 deg.c and several middle reflux stages.
As a further scheme of the invention: 15-50 layers of theoretical plates of the re-desorption tower, 5-30 layers of feeding positions, 0.6-1 MPag of pressure at the top of the tower, 10-25 ℃ of temperature at the top of the tower and 190-230 ℃ of temperature at the bottom of the tower.
As a further scheme of the invention: the desorption tower has 20-70 layers of theoretical plates and 10-40 layers of feeding positions, the pressure at the top of the tower is 1.5-3 MPag, the temperature at the top of the tower is 6-30 ℃, and the temperature at the bottom of the tower is 60-85 ℃.
As a further scheme of the invention: the depropanizer has 20-80 layers of theoretical plates and 10-50 layers of feeding positions, the pressure at the top of the tower is 0.6-1.5 MPag, the temperature at the top of the tower is 15-35 ℃, and the temperature at the bottom of the tower is 60-90 ℃.
Compared with the prior art, the invention has the beneficial effects that:
1. the invention takes propane or C3 fraction rich in propane as an absorbent, takes toluene or xylene and industrial hexane as a reabsorber, and absorbs and separates saturated dry gas produced by each device of a refinery under the condition of intercooling (-15 to-35 ℃), the recovery rates of ethane and propane can reach more than 98 percent, meanwhile, the circulation amount and the loss amount of the absorbent are relatively small, the absorbent does not need to be supplemented basically, and the energy consumption of the device is low. The method improves the recovery rate of ethane and propane, and solves the problems of large consumption of absorbent, high energy consumption, large scale of tower and other equipment, large investment, low recovery rate, no dryness of dry gas to be delivered and the like in the separation process of saturated dry gas C1, C2 and C3 in the existing refinery.
2. In the method, propane or C3 fraction rich in propane is used as an absorbent, so that the effect of absorbing C2 is better, and the consumption of the absorbent is small. And the propane or the C3 fraction rich in propane is produced by the device, so that the operation cost is reduced. Meanwhile, absorption is carried out under an intercooling condition, the dosage of an absorbent is small, the scale of a tower and other equipment is small, and the investment is low.
3. The invention takes toluene (or xylene and industrial hexane) as the reabsorber, has better effect of absorbing C3, less C3 components carried by methane fuel gas, small circulation amount of the reabsorber, and the carrying amount of heavy components in dry gas is not more than 0.2mol percent. And the reabsorber is produced by the refinery, so that the operation cost is reduced.
4. The invention does not use equipment such as a cold box, an ethylene machine and the like, has low refrigeration load, greatly reduces the use of low-temperature materials and cold insulation materials, and has low device investment.
5. The tower bottoms of the absorption tower, the desorption tower and the depropanizing tower are low in temperature, and a reboiler at the tower bottom can adopt hot water, low-temperature process material waste heat and the like, so that the energy consumption is low.
Drawings
FIG. 1 is a schematic structural diagram of a method for combined absorption, recovery and separation of low carbon hydrocarbons in refinery saturated dry gas.
In the figure: 1. a gas compressor; 2. impurity removal equipment; 3. a cooler; 4. an absorption tower; 5. a desorption tower; 6. a reabsorption tower; 7. then desorbing the tower; 8. a depropanizer.
Detailed Description
The technical solution of the present patent will be described in further detail with reference to the following embodiments.
Referring to fig. 1, a method for combined absorption, recovery and separation of low carbon hydrocarbons in refinery saturated dry gas includes the following steps:
s1, gradually compressing saturated dry gas of a refinery to 3-4.5 MPag by a gas compressor 1, removing impurities by an impurity removing device 2, gradually cooling to-15 to-35 ℃ by a cooler 3, and allowing the gas to enter an absorption tower 4;
s2, adopting liquid-phase propane or a C3 fraction rich in propane as an absorbent in the absorption tower 4, wherein the absorbent enters the absorption tower 4 from the top of the tower to absorb components C2 and above C2 in saturated dry gas; the material at the bottom of the absorption tower 4 is sent to a desorption tower 5, and the gas phase at the top of the absorption tower 4 enters a reabsorption tower 6;
s3, absorbing C2 and C3 components carried out by the gas phase at the top of the absorption tower 4 by adopting liquid-phase methylbenzene or dimethylbenzene and industrial hexane as a reabsorber in the reabsorption tower 6, introducing the gas at the top of the reabsorber 6 serving as dry gas into a fuel gas pipe network, and feeding the liquid phase at the bottom of the reabsorber 6 into a reabsorption tower 7;
s4, condensing the gas phase at the top of the re-desorption tower 7, then returning the condensed liquid rich in propane to the absorption tower 4 after pressurization and cooling by a pump, and cooling and circularly returning the liquid phase at the bottom of the re-desorption tower 7 to the top of the re-absorption tower 6 by taking the liquid phase as a re-absorbent;
s5, obtaining an ethane and propane mixed component at the top of the desorption tower 5; a part of the C3+ liquid phase at the bottom of the desorption tower 5 is pressurized and cooled and then circularly returned to the absorption tower 4, and the rest part enters the depropanizing tower 8 for continuous separation or all enters the depropanizing tower 8 for continuous separation;
s6, separating the top of the depropanizing tower 8 to obtain high-purity propane, mixing one part of the high-purity propane serving as a circulating absorbent with a circulating material at the bottom of the desorption tower 5 after pressurization and cooling, returning the mixture to the absorption tower 4, and sending the other part of the high-purity propane serving as a propane product out of the device; c4+ liquid phase obtained at the bottom of the depropanizing tower 8 is sent to a subsequent device for treatment.
Further, in the step S1, the refinery saturated dry gas is gradually compressed by 3-4 sections; the impurity removal process comprises amine washing, alkali washing and drying.
Furthermore, the absorption tower 4 has 20-70 layers of theoretical plates and 10-40 layers of feeding positions, the pressure at the top of the tower is 3-4.5 MPag, the temperature at the top of the tower is-35-10 ℃, the temperature at the bottom of the tower is 60-90 ℃, and the absorption tower 4 is provided with a plurality of middle-section reflux.
Furthermore, the reabsorption tower 6 has 15-70 layers of theoretical plates and 5-40 layers of feeding positions, the pressure at the top of the tower is 1.5-2.5 MPag, the temperature at the top of the tower is 0-15 ℃, and the reabsorption tower 6 is provided with a plurality of middle-section refluxes.
Furthermore, the re-desorption tower 7 has 15-50 layers of theoretical plates and 5-30 layers of feeding positions, the pressure at the top of the tower is 0.6-1 MPag, the temperature at the top of the tower is 10-25 ℃, and the temperature at the bottom of the tower is 190-230 ℃.
Furthermore, the desorption tower 5 comprises 20-70 layers of theoretical plates and 10-40 layers of feeding positions, the pressure at the top of the tower is 1.5-3 MPag, the temperature at the top of the tower is 6-30 ℃, and the temperature at the bottom of the tower is 60-85 ℃.
Furthermore, the depropanizer 8 has 20-80 layers of theoretical plates, 10-50 layers of feeding positions, the pressure at the top of the tower is 0.6-1.5 MPag, the temperature at the top of the tower is 15-35 ℃, and the temperature at the bottom of the tower is 60-90 ℃.
The composition of the saturated dry gas, the absorbent and the reabsorber in this example is shown in the following table:
| saturated dry gas | Absorbent agent | Reabsorbing agent | |
| Mass flow rate t/h | 49.17 | 70 | 150 |
| Molar composition (mol%) | |||
| Hydrogen gas | 50.931 | ||
| Nitrogen gas | 8.560 | ||
| Carbon monoxide | 0.207 | ||
| Oxygen gas | 0.087 | ||
| Carbon dioxide | 1.290 | ||
| Methane | 19.990 | ||
| Ethylene (CO) process | 0.382 | ||
| Ethane (III) | 9.814 | 0.016 | |
| Hydrogen sulfide | - | ||
| Propylene (PA) | 0.040 | 0.244 | |
| Propane | 4.070 | 99.739 | |
| C4 | 3.420 | ||
| C5 | 0.910 | ||
| C6+ | 0.300 | ||
| Toluene | - | 100 |
The saturated dry gas of the refinery comes from other devices of the refinery and enters the gas compressor 1, and the pressure is increased to 3.85MPag after four-stage compression. The pressurized saturated dry gas passes through an impurity removal device 2, is cooled to about minus 20 ℃ by a cooler 3, and enters an absorption tower 4. The absorption tower 4 takes propane as an absorbent, enters from the top of the tower and absorbs C2 and above components in the gas. The number of theoretical plates of the absorption tower 4 is preferably 45 layers, the operation pressure at the top of the tower is 3.72MPag, the temperature at the top of the tower is-19 ℃, the temperature at the bottom of the tower is 83 ℃, and a plurality of middle-section heat taking reflux is arranged on the absorption tower 4. The gas at the top of the absorption tower 4 enters a reabsorption tower 6, the theoretical plate number of the reabsorption tower 6 is preferably 30 layers, the operation pressure is 2.3MPag, the temperature at the top of the tower is 2.7 ℃, and the reabsorption tower 6 is provided with a plurality of middle-stage reflux. The rich absorption liquid at the bottom of the absorption tower 4 enters a desorption tower 5 for separation. The reabsorption tower 6 adopts toluene as a reabsorption agent 2 to absorb C2 and C3 components brought out by the gas phase at the top of the absorption tower 4, methane-hydrogen fuel gas (dry gas) obtained at the top of the reabsorption tower 6 is merged into a fuel gas pipe network, and the liquid phase at the bottom of the reabsorption tower 6 is sent to a reabsorption tower 7. The number of theoretical plates of the re-desorption tower 7 is preferably 28 layers, the operation pressure is 0.8MPag, the tower top temperature is 15 ℃, the tower bottom temperature is 213.6 ℃, the condensate rich in propane obtained by separation at the tower top of the re-desorption tower 7 is pressurized by a pump and then returns to the absorption tower 4, and the toluene at the tower bottom of the re-desorption tower 7 is used as a reabsorber to be cooled and then circularly returns to the tower top of the re-absorption tower 6. The number of theoretical plates of the desorption tower 5 is preferably 30, the operation pressure is 2.3MPag, the tower top temperature is about 24.7 ℃, the tower bottom temperature is 71 ℃, the mixed component of ethane and propane is separated from the tower top of the desorption tower 5 and is sent to a downstream ethylene cracking device, wherein the propane amount is basically equal to the propane amount in the saturated dry gas of a refinery; and (3) a tower bottom C3+ component 24, wherein a part of materials are pressurized and cooled and then circularly returned to the absorption tower 4, the rest of materials enter the depropanizing tower 8 for further separation, and all materials enter the depropanizing tower 8 for separation in the embodiment. The number of theoretical plates of the depropanizer 8 is preferably 40, the operating pressure is 0.8MPag, the temperature at the top of the tower is about 22.8 ℃, the temperature at the bottom of the tower is 75.64 ℃, high-purity propane separated from the top of the depropanizer 8 is used as a circulating absorbent, is pressurized and cooled, is mixed with a circulating material at the bottom of the desorber 5 and then returns to the absorption tower 4, and no propane product is produced; c4+ liquid phase from the tower bottom of the depropanizing tower 8 is sent to a subsequent device for treatment.
The isolated products are shown in the following table:
in this example, the ethane recovery was 99.96wt%, propane recovery was 99.9wt%, C2C3 recovery was 99.93wt%, and the entrainment of heavies in the methane fuel gas was less than 0.2mol%.
The working principle of the invention is as follows: in the invention, the content of C2 and C3 in the saturated dry gas of the refinery is about 20mol percent, and the rest is hydrogen, methane, water, impurities, components with more than 4 carbon atoms and the like. The invention is particularly limited to the absorbent which is propane or a C3 fraction rich in propane and the reabsorber which is toluene or xylene, industrial hexane or other components.
The specific process flow is as follows: saturated dry gas from a refinery enters a gas compressor 1 at the temperature of 40 ℃, is compressed to 3-4.5 MPag through three-stage or four-stage compression, is desulfurized, decarbonized, dried and subjected to other impurity removal, and is cooled to-15 to-35 ℃ step by step and then enters an absorption tower 4. The absorption tower 4 takes propane or C3 fraction rich in propane as an absorbent, the pressure of the absorption tower 4 is 3-4.5 MPag, the temperature of the top of the tower is-35-10 ℃, the temperature of the bottom of the tower is 60-90 ℃, the theoretical plates are 20-70 layers, the feeding positions are 10-40 layers, and the absorption tower 4 is provided with a plurality of middle-section refluxes. The gas phase at the top of the absorption tower 4 enters a reabsorption tower 6, the reabsorption tower 6 has 15-70 layers of theoretical plates and 5-40 layers of feeding positions, the pressure at the top of the tower is 1.5-2.5 MPag, the temperature at the top of the tower is 0-15 ℃, and the reabsorption tower 6 is provided with a plurality of middle-section refluxes. The rich absorption liquid at the bottom of the absorption tower 4 enters a desorption tower 5 for separation. The reabsorption tower 6 adopts toluene as a reabsorber to absorb part of C2 and C3 components carried by non-condensable gas at the top of the absorption tower 4, methane-hydrogen fuel gas (dry gas) obtained at the top of the reabsorber 6 enters a fuel gas pipe network, and products at the bottom of the reabsorber 6 are sent to a reabsorption tower 7. Then desorbing tower 7 with theoretical plate 15-50 layers and feeding position 5-30 layers, tower top pressure 0.6-1 MPag, tower top temperature 10-25 deg.c and tower bottom temperature 190-230 deg.c. The condensate rich in propane obtained by separation at the top of the re-desorption tower 7 is pressurized by a pump and then returns to the absorption tower 4, and the toluene at the bottom of the re-desorption tower 7 is used as a re-absorbent and returns to the top of the re-absorption tower 6 through cooling circulation. The pressure at the top of the desorption tower 5 is 1.5-3 MPag, the temperature at the top of the desorption tower is 6-30 ℃, the temperature at the bottom of the desorption tower is 60-85 ℃, the theoretical plate is 20-70 layers, and the feeding position is 10-40 layers; the mixed component of ethane and propane is separated from the top of the desorption tower 5 (high-purity ethane can also be obtained by separation), the C3+ component at the bottom of the tower, one part of the material is pressurized and cooled and then circularly returned to the absorption tower 4, and the rest part of the material enters the depropanizing tower 8 for further separation (or all the material enters the depropanizing tower 8 for continuous separation). The pressure at the top of the depropanizing tower 8 is 0.6-1.5 MPag, the temperature at the top of the depropanizing tower is 15-35 ℃, the temperature at the bottom of the depropanizing tower is 60-90 ℃, the theoretical plates are 20-80 layers, and the feeding position is 10-50 layers; a part of high-purity propane separated from the top of the depropanizing tower 8 is taken as a circulating absorbent, is pressurized and cooled, is mixed with the circulating material at the bottom of the desorption tower 5 and then returns to the absorption tower 4, and a part of high-purity propane is taken as a product outlet device; c4+ liquid phase from the tower bottom of the depropanizing tower 8 is sent to a subsequent device for treatment.
Although the preferred embodiments of the present patent have been described in detail, the present patent is not limited to the above embodiments, and various changes can be made without departing from the spirit of the present patent within the knowledge of those skilled in the art.
Claims (7)
1. A method for combined absorption, recovery and separation of low-carbon hydrocarbons in saturated dry gas of a refinery is characterized by comprising the following steps:
s1, gradually compressing saturated dry gas of a refinery to 3-4.5 MPag through a gas compressor (1), removing impurities through an impurity removal device (2), gradually cooling to-15 to-35 ℃ through a cooler (3), and entering an absorption tower (4);
s2, adopting liquid-phase propane as an absorbent in the absorption tower (4), wherein the absorbent enters the absorption tower (4) from the top of the tower to absorb C2 and components above C2 in saturated dry gas; the material at the bottom of the absorption tower (4) is sent to a desorption tower (5), and the gas phase at the top of the absorption tower (4) enters a reabsorption tower (6);
s3, absorbing C2 and C3 components carried out by the gas phase at the top of the absorption tower (4) by adopting liquid-phase methylbenzene as a reabsorber in the reabsorption tower (6), introducing the gas at the top of the reabsorption tower (6) as dry gas into a fuel gas pipe network, and feeding the liquid phase at the bottom of the reabsorption tower (6) into a reabsorption tower (7);
s4, condensing the gas phase at the top of the re-desorption tower (7) to obtain condensate rich in propane, pressurizing and cooling the condensate by a pump, returning the condensate to the absorption tower (4), and cooling and circularly returning the liquid phase at the bottom of the re-desorption tower (7) to the top of the re-absorption tower (6) as a re-absorbent;
s5, obtaining an ethane and propane mixed component at the top of the desorption tower (5); part of the C3+ liquid phase at the bottom of the desorption tower (5) is pressurized and cooled and then circularly returned to the absorption tower (4), and the rest part enters a depropanizing tower (8) for continuous separation;
s6, separating the top of the depropanizing tower (8) to obtain high-purity propane, mixing one part of the high-purity propane serving as a circulating absorbent with a circulating material at the bottom of the desorption tower (5) after pressurization and cooling, returning the mixture to the absorption tower (4), and sending the other part of the high-purity propane serving as a propane product out of the device; c4+ liquid phase obtained at the bottom of the depropanizing tower (8) is sent to a subsequent device for treatment.
2. The method for combined absorption, recovery and separation of low carbon hydrocarbons in refinery saturated dry gas according to claim 1, wherein in step S1, the refinery saturated dry gas is compressed by 3-4 stages; the impurity removal process comprises amine washing, alkali washing and drying.
3. The combined absorption, recovery and separation method of low carbon hydrocarbons in refinery saturated dry gas according to claim 1, wherein the absorption tower (4) has 20-70 layers of theoretical plates and 10-40 layers of feeding positions, the overhead pressure is 3-4.5 MPag, the overhead temperature is-35-10 ℃, the bottom temperature is 60-90 ℃, and the absorption tower (4) is provided with a plurality of middle-stage reflux streams.
4. The method for combined absorption, recovery and separation of low carbon hydrocarbons in refinery saturated dry gas according to claim 1, wherein the reabsorption tower (6) has 15-70 layers of theoretical plates, 5-40 layers of feeding positions, 1.5-2.5 MPag of overhead pressure, 0-15 ℃ of overhead temperature, and a plurality of middle reflux streams in the reabsorption tower (6).
5. The method for combined absorption, recovery and separation of low carbon hydrocarbons in refinery saturated dry gas according to claim 1, wherein the re-desorption tower (7) has 15-50 layers of theoretical plates, 5-30 layers of feeding positions, 0.6-1 MPag of overhead pressure, 10-25 ℃ of overhead temperature and 190-230 ℃ of bottom temperature.
6. The method for combined absorption, recovery and separation of low carbon hydrocarbons in saturated dry gas of refinery according to claim 1, wherein the desorption tower (5) has 20-70 layers of theoretical plates, 10-40 layers of feeding positions, 1.5-3 MPag of overhead pressure, 6-30 ℃ of overhead temperature and 60-85 ℃ of bottom temperature.
7. The method for combined absorption, recovery and separation of low carbon hydrocarbons in refinery saturated dry gas according to claim 1, wherein the depropanizer (8) has 20-80 layers of theoretical plates, 10-50 layers of feeding positions, 0.6-1.5 MPag of overhead pressure, 15-35 ℃ of overhead temperature and 60-90 ℃ of bottom temperature.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202110293757.4A CN113354506B (en) | 2021-03-19 | 2021-03-19 | Method for recovering and separating low-carbon hydrocarbons from refinery saturated dry gas by combined absorption |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202110293757.4A CN113354506B (en) | 2021-03-19 | 2021-03-19 | Method for recovering and separating low-carbon hydrocarbons from refinery saturated dry gas by combined absorption |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN113354506A CN113354506A (en) | 2021-09-07 |
| CN113354506B true CN113354506B (en) | 2023-02-28 |
Family
ID=77524993
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202110293757.4A Active CN113354506B (en) | 2021-03-19 | 2021-03-19 | Method for recovering and separating low-carbon hydrocarbons from refinery saturated dry gas by combined absorption |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN113354506B (en) |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN115253604B (en) * | 2022-08-09 | 2024-01-26 | 大连理工大学 | Device and method for separating carbon-rich two-carbon three-dry gas by NMP |
Family Cites Families (9)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101063048A (en) * | 2006-04-27 | 2007-10-31 | 中国石油化工股份有限公司 | Method for separating plant catalytic dry gas by employing middle-cool-oil absorption process |
| CN104419465B (en) * | 2013-09-10 | 2016-12-07 | 中国石油化工股份有限公司 | A kind of oil refinery dry gas recovery system and dry-gas recovery method |
| CN104419464B (en) * | 2013-09-10 | 2017-01-11 | 中国石油化工股份有限公司 | Dry gas recovery system and dry gas recovery method for refinery plant |
| CN104557384B (en) * | 2013-10-23 | 2017-02-15 | 中国石油化工股份有限公司 | Refinery mixed dry gas recovery system and recovery method |
| CN104557387B (en) * | 2013-10-23 | 2017-02-15 | 中国石油化工股份有限公司 | Refinery mixed dry gas recovery system and recovery method |
| CN104892340A (en) * | 2015-06-10 | 2015-09-09 | 天津大学 | Three-tower device and method for recycling ethylene and ethane from dry gas through oil absorption |
| CN106608801B (en) * | 2015-10-26 | 2019-06-28 | 中国石油化工股份有限公司 | A method of separation coal aromatic hydrocarbons by-product dry gas |
| CN107099340B (en) * | 2017-06-22 | 2020-07-28 | 山东京博石油化工有限公司 | Device and method for removing propylene in dry gas |
| CN109678635B (en) * | 2017-10-19 | 2022-03-15 | 中国石油化工股份有限公司 | Saturated hydrocarbon cracking gas separation system and utilization method of ethane/propane-rich saturated hydrocarbon |
-
2021
- 2021-03-19 CN CN202110293757.4A patent/CN113354506B/en active Active
Also Published As
| Publication number | Publication date |
|---|---|
| CN113354506A (en) | 2021-09-07 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN109912379B (en) | Refinery dry gas separation method and device | |
| CN104557384B (en) | Refinery mixed dry gas recovery system and recovery method | |
| CN104557387A (en) | Refinery mixed dry gas recovery system and recovery method | |
| EP4053251A1 (en) | Method and device for recovering c2-c4 components in methane-containing industrial gas | |
| CN113121301B (en) | Recovery method of light hydrocarbon in refinery dry gas | |
| CN113354506B (en) | Method for recovering and separating low-carbon hydrocarbons from refinery saturated dry gas by combined absorption | |
| CN111320523B (en) | Method and device for separating ethylene from refinery dry gas | |
| CN113354502B (en) | Method for separating low-carbon hydrocarbon from unsaturated dry gas by combined absorption and recovery | |
| CN111393252A (en) | Light hydrocarbon separation device and method | |
| CN112410070B (en) | Energy-saving process and device for recovering carbon dioxide from refinery dry gas | |
| CN112279746B (en) | Method and device for separating three dry gases rich in carbon dioxide | |
| CN109748771A (en) | The method for recycling carbon two in oil refinery dry gas | |
| CN113350974B (en) | H in saturated dry gas2C1, C2 and C3 separation and recovery method | |
| CN113354501A (en) | Separation method for recovering C1, C2 and C3 in catalytic rich gas by combined absorption method | |
| CN113387769A (en) | Separation method for recovering C1, C2 and C3 in refinery saturated dry gas by combined absorption method | |
| CN112725032B (en) | Method and device for recovering carbon dioxide component in dry gas | |
| CN115253604B (en) | Device and method for separating carbon-rich two-carbon three-dry gas by NMP | |
| CN112728869B (en) | Method and device for recovering three components of carbon two in dry gas | |
| CN112707785B (en) | Pyrolysis gas separation system with cold energy recovery function and separation method | |
| CN104557385B (en) | A kind of refinery's mixing dry gas recovery system and recovery method | |
| CN113755201B (en) | Method for concentrating two or more components in dry gas of light and heavy refinery, device and application thereof | |
| CN113355135A (en) | Separation method of saturated dry gas of refinery plant | |
| CN114432843B (en) | Method and device for separating gaseous hydrocarbon material | |
| CN116023216A (en) | Method for recycling ethane and propane in refinery saturated dry gas, device and application thereof | |
| CN116023220A (en) | Method for recycling carbon two and carbon three components in refinery dry gas, device and application thereof |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination | ||
| GR01 | Patent grant | ||
| GR01 | Patent grant |