CN112760134B - Oil gas recovery method and device - Google Patents
Oil gas recovery method and device Download PDFInfo
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- CN112760134B CN112760134B CN201911066141.2A CN201911066141A CN112760134B CN 112760134 B CN112760134 B CN 112760134B CN 201911066141 A CN201911066141 A CN 201911066141A CN 112760134 B CN112760134 B CN 112760134B
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- C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
- C10G—CRACKING HYDROCARBON OILS; PRODUCTION OF LIQUID HYDROCARBON MIXTURES, e.g. BY DESTRUCTIVE HYDROGENATION, OLIGOMERISATION, POLYMERISATION; RECOVERY OF HYDROCARBON OILS FROM OIL-SHALE, OIL-SAND, OR GASES; REFINING MIXTURES MAINLY CONSISTING OF HYDROCARBONS; REFORMING OF NAPHTHA; MINERAL WAXES
- C10G53/00—Treatment of hydrocarbon oils, in the absence of hydrogen, by two or more refining processes
- C10G53/02—Treatment of hydrocarbon oils, in the absence of hydrogen, by two or more refining processes plural serial stages only
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Abstract
The invention belongs to the field of chemical industry, and particularly discloses oil gasThe method and the device for recycling the light hydrocarbon have the advantages that the gasoline, the C4 and the components below C4 are separated in advance before the light hydrocarbon is separated, so that the gasoline is not required to be adopted to absorb the liquefied gas components in the subsequent flow, the consumption of the absorbent circulation is saved, meanwhile, the gas-phase hydrocarbon and the liquid-phase hydrocarbon are independently desulfurized at the outlet of the debutanizer respectively, and the material flow does not contain H any more in the light hydrocarbon separation process2S, the material requirement of a light hydrocarbon separation and recovery system is reduced, and the safety of the whole process is ensured; meanwhile, the invention has simple process flow, mild operation condition and less energy consumption.
Description
Technical Field
The invention belongs to the field of chemical industry, and particularly relates to an oil gas recovery method and device.
Background
Light hydrocarbon refers to the components of methane, ethane, ethylene, propane, propylene, carbon and the like obtained in the petrochemical process, and the light hydrocarbon separation process is always the key point of attention of the petrochemical process. The existing process with high gas yield such as catalytic cracking, hydrocracking, delayed coking and the like usually adopts absorption stabilization to recover liquefied gas (C3/C4) components to realize liquefied gas components and dry gas (H)2/C1/C2) and stabilizing the gasoline to ensure the qualified vapor pressure of the gasoline.
The absorption stabilizing process mainly comprises four towers: the absorption tower, the reabsorption tower, the desorption tower and the stabilizing tower, wherein the recovery rate of the liquefied gas is controlled by the absorption tower and the reabsorption tower, and the specification of the liquefied gas is ensured by the desorption tower (controlling the content of carbon five) and the stabilizing tower (controlling the content of carbon five). The main characteristic is that gasoline is used as absorbent under certain pressure (1.3 MPaG-1.6 MPaG) and normal temperature, most of liquefied gas components and a small amount of carbon dioxide in the rich gas are absorbed, and then the absorbed light components such as carbon dioxide are desorbed under proper conditions. Therefore, the method of absorption and desorption can realize the separation of the carbon two and the carbon three under the milder operation condition, and avoid the adoption of a rectification method (with higher pressure, lower temperature and refrigeration requirement) to separate the carbon two and the carbon three, thereby reducing the investment and the energy consumption; the cost is that the top gas of the desorption tower contains certain components such as liquefied gas and the like besides carbon dioxide, and the desorption gas returns to the absorption tower again, so that the circulation of the components of the liquefied gas between absorption and desorption is caused, and the energy consumption of an absorption stabilizing system is increased.
Through research and analysis, the prior absorption stabilization process method has the following defects:
(1) the absorption stabilizing system adopts stable gasoline as an absorbent to recover liquefied gas components, absorbs the components at normal temperature without refrigeration, and has large gasoline circulation amount in order to ensure the recovery rate of the liquefied gas.
(2) Gasoline circulates among the gasoline absorption tower, the desorption tower and the stabilizing tower, the temperature of the bottoms of the ethane desorption tower and the stabilizing tower is higher, the thermal load of a reboiler at the bottom of the tower is larger, and the energy consumption is higher.
(3) The stabilizing tower (debutanizer) is arranged at the tail end, the flow path of the gasoline is long, and the energy consumption is high;
(4) the desulfurization is arranged on a dry gas and liquefied gas product line, and an absorption stabilizing system contains H2S, the requirement on the material is high, and potential safety hazards may exist in normal operation.
The present invention has been made to solve the above-mentioned problems occurring in the prior art.
Disclosure of Invention
The invention aims to provide a device and a method for separating and recovering liquefied gas from light hydrocarbon, which have simple process flow and mild operation conditions, can realize the high-efficiency separation and recovery of three-carbon and four-carbon components, and simultaneously, because a light hydrocarbon recovery system does not contain H2S, the material requirement of the light hydrocarbon recovery system is reduced, and the operation is safer.
In order to achieve the above object, the present invention provides a method for oil and gas recovery, the method comprising:
(1) separation: oil gas from an upstream device after reaction is sent to a fractionating tower for separation, oil slurry, diesel oil and recycle oil are respectively extracted from the bottom and a lateral line of the fractionating tower, gas phase at the top of the fractionating tower is sent to a first-stage gas-liquid separation tank after being cooled, gas phase at the top of the tank is sent to a second-stage gas-liquid separation tank after being condensed again, liquid phase part at the bottom of the tank is sent to the top of the fractionating tower, and the rest part of the liquid phase part is sent to a debutanizer; compressing the gas phase at the top of the secondary gas-liquid separation tank, and then sending the compressed gas phase to a debutanizer, boosting the pressure of the liquid phase at the bottom of the tank, and then sending the liquid phase to the debutanizer;
(2) removing butane: the gas phase and the liquid phase from the step (1) enter a debutanizer, the gas phase distilled from the top of the debutanizer enters a reflux tank at the top of the tower through condensation to separate a gas phase and a liquid phase, then impurities are respectively removed, and at least part of the liquid phase at the bottom of the debutanizer is taken as a stable gasoline product to be extracted;
(3) gas-phase impurity removal: gas phase on the top of a reflux tank at the top of the debutanizer tower is sequentially subjected to H removal in a rich gas desulfurization tower by taking lean amine liquid as an absorbent2S and CO2In the gas-rich alkaline tower, the mercaptan and a small amount of H are removed by alkali liquor2S and CO2Then the mixture is sent to a post cooler after being pressurized and cooled;
(4) liquid phase impurity removal: removing H from the liquid phase at the bottom of the reflux tank at the top of the debutanizer in turn in a liquid hydrocarbon desulfurization tower2S and CO2In the liquid hydrocarbon sweetening reactor, alkali liquor is used to remove mercaptan and small quantity of H2S and CO2Then sending the mixture to an aftercooler;
(5) post-cooling: the gas phase and the liquid phase are preliminarily mixed and cooled in a postcooler and then are sent to a feeding tank;
(6) feeding: after the mixture flow from the aftercooler is mixed and gas-liquid balanced in a feeding tank, the gas phase at the top of the tank is sent to a liquefied gas recovery tower, and the liquid phase at the bottom of the tank is sent to a demethanizer;
(7) demethanization: removing methane from the liquid phase at the bottom of the feed tank in a demethanizer, simultaneously removing a small part of components with the carbon number of C2 and more than C2, sending the gas phase at the top of the demethanizer to a liquefied gas recovery tower, and sending the liquid phase at the bottom of the demethanizer to a deethanizer;
(8) deethanizing: separating C2 component from the liquid phase at the bottom of the demethanizer in a deethanizer, collecting the separated mixed C2 component from the top of the deethanizer or sending the component to a liquefied gas recovery tower, and sending the liquid phase components with C3 and above C3 at the bottom of the deethanizer to a depropanizer;
(9) depropanizing: further separating the liquid phase component from the bottom of the deethanizer in a depropanizer, and extracting the separated C3 component from the upper part of the depropanizer as a C three product and the bottom of the depropanizer as a C four product;
(10) and (3) recovering liquefied gas: in the liquefied gas recovery tower, stabilized gasoline is used as an absorbent to absorb liquefied gas components in a gas phase in the tower, the gas phase at the top of the liquefied gas recovery tower is extracted as a dry gas product, and a liquid phase at the bottom of the liquefied gas recovery tower returns to the debutanizer.
The invention has wide application range, and the high-temperature oil gas (including the component H) after reaction in the common processes with higher light hydrocarbon profit, such as catalytic cracking, delayed coking, flexicoking, slurry bed hydrocracking and the like in the petrochemical production2C1-C4 light hydrocarbons, gasoline, diesel oil, heavy oil, etc.) can be separated by the device of the invention to recover liquefied gas.
As a preferable scheme of the invention, in order to fully utilize the excessive heat of the high-temperature oil gas of the upstream device, the oil gas of the upstream device is further separated by using a fractionating tower, the operation temperature at the top of the fractionating tower is 100-140 ℃, and the pressure is 0.1-0.35 MPaG. The tower top of the fractionating tower is provided with two-stage gas-liquid separation, gas phase extracted from the tower top of the fractionating tower is sequentially subjected to cooling, gas-liquid separation and re-cooling, after the process of gas-liquid separation again, a large part of gasoline is separated from a first-stage gas-liquid separation tank and then directly sent to a debutanizer so as to avoid repeated cooling and heating of the gasoline and reduce investment and energy consumption, oil gas is subjected to two-stage gas-liquid separation, the gas phase is sent to the debutanizer through boosting, the operating temperature of the first-stage gas-liquid separation tank at the tower top of the fractionating tower is 60-80 ℃, and the pressure is 0.07-0.32 MPaG; the operation temperature of the second-stage gas-liquid separation tank at the top of the fractionating tower is 35-50 ℃, and the pressure is 0.03-0.28 MPaG.
In a preferable scheme of the invention, in order to further separate gasoline from carbon four and components below carbon four, the operation temperature at the top of the debutanizer is 55-85 ℃, and the operation pressure is 1.0-1.3 MPaG; the operation temperature at the bottom of the tower is 160-210 ℃, and the temperature of the reflux tank at the top of the debutanizer is 35-45 ℃.
In the invention, in order to meet the requirement of related product recovery, the gas-phase and liquid-phase hydrocarbons need to be subjected to impurity removal independently before next separation, and the impurity removal mainly comprises amine elution H2S and CO2And alkaline washing to remove mercaptan. Preferably, the operation temperature of the rich gas desulfurization tower is 35-45 ℃, and the operation pressure is 0.95-1.25 MPaG; the operating temperature of the liquid hydrocarbon desulfurization tower is 35-45 ℃, and the operating pressure is 2.2-3.0 MPaG; the operating temperature of the feeding tank is 5-20 ℃, and the operating pressure is 2.0-2.8 MPaG.
In the present invention, amine elution H2S can be carried out by adopting a compound amine liquid solvent (namely, a modified solvent based on MDEA) and carrying out H2S and CO2In which H is2S can be removed to less than 10ppmw, CO2The removal efficiency can reach 90-99 wt%, and the amine washing part realizes H2S and CO2After the high-efficiency removal, the gas-phase hydrocarbon and the liquid-phase hydrocarbon can effectively enter the stream of the alkaline washing mercaptan removal reactor to remove H2S and CO2And further reducing the consumption of alkali liquor.
Because the main recovery target of the invention is C3/C4 components, and C2 components are not required to be recovered, according to the principle that the saturated vapor pressure of the C3/C4 components is lower, most of the C3/C4 components can be condensed by directly adopting one-time gas-liquid separation under the process operation condition adopted by the invention, and then the condensate is subjected to demethanization, deethanization and depropanization processes in turn. According to the invention, the temperature of the feeding tank is preferably 5-20 ℃ and the pressure is preferably 2.0-2.8 MPaG.
In the invention, the uncondensed gas phase is sent to a liquefied gas recovery tower to recover the entrained liquefied gas components, preferably, the temperature of the liquefied gas recovery tower is 5-20 ℃, and the pressure is 2.0-2.8 MPaG; the absorbent is a stable gasoline product extracted from the bottom of the debutanizer, and does not need to be supplemented from the outside of the system.
In order to ensure the product quality of the downstream recovered propylene, reduce the content of the C2 component and reduce the circulating amount of each component, the invention is provided with a demethanizer and a deethanizer in sequence.
As a preferable scheme of the invention, the temperature of the top of the demethanizer is 10-30 ℃, the pressure is 2.2-3.0 MPaG, and the temperature of the bottom of the demethanizer is 60-100 ℃; the temperature of the top of the deethanizer is 5-20 ℃, the pressure is 2.6-3.2 MPaG, and the temperature of the bottom of the deethanizer is 95-120 ℃; the tower top temperature of the depropanizing tower is 50-65 ℃, the pressure is 1.6-2.0 MPaG, and the tower bottom temperature is 95-120 ℃. Because the temperature of the bottom of the demethanizer and the deethanizer is low and the circulating amount of each component is small, the load of a reboiler at the bottom of the tower can be reduced, and the energy is saved.
As a preferable scheme of the invention, when the carbon dioxide product needs to be recovered, the carbon dioxide product obtained from the top of the deethanizer can be directly led out, subjected to impurity removal and sent to a downstream ethylene device for further recovery, the carbon dioxide product mainly comprises ethylene and ethane and contains about 20 v% of propylene, and the recovery rate of the carbon dioxide component is 50-60 wt%.
As a preferable embodiment of the present invention, in order to further separate propylene having a purity of not less than 99.6 vol%, the mixed C3 component may be further rectified, and specifically, the method further includes:
(11) and (3) propylene rectification: and (3) sending the carbon product extracted from the upper part of the depropanizing tower to a propylene rectifying tower for further rectification, wherein the gas phase at the top of the propylene rectifying tower is extracted as a propylene product, and the liquid phase at the bottom of the propylene rectifying tower is extracted as a propane product. Wherein, the temperature of the propylene rectifying tower is preferably 45-60 ℃, and the pressure is preferably 1.7-2.0 MPaG.
In another aspect, the present invention provides an apparatus for recovering oil and gas, the apparatus comprising: the system comprises an oil gas feeding pipeline, a fractionating tower, a primary heat exchanger, a primary gas-liquid separating tank, a secondary heat exchanger, a secondary gas-liquid separating tank, a compressor I, a debutanizer, a rich gas desulfurization tower, a rich gas alkaline washing tower, a liquid hydrocarbon desulfurization tower, a liquid hydrocarbon sweetening reactor, a compressor II, a cooler, an after cooler, a feeding tank, a demethanizer, a deethanizer, a depropanizer and a liquefied gas recovery tower;
wherein, the oil gas feed pipeline is connected with the fractionating tower,
the top of the fractionating tower is provided with a first-stage heat exchanger, a first-stage gas-liquid separation tank, a second-stage heat exchanger and a second-stage gas-liquid separation tank, a diesel oil extraction pipeline and a recycle oil extraction pipeline are arranged on the lateral line, and an oil slurry extraction pipeline is arranged at the bottom of the fractionating tower; the top of the fractionating tower is sequentially connected with a first-stage heat exchanger and a first-stage gas-liquid separation tank in series, the top of the first-stage gas-liquid separation tank is sequentially connected with a second-stage heat exchanger and a second-stage gas-liquid separation tank in series, and the bottom of the fractionating tower is respectively connected with the fractionating tower and the debutanizer; the top of the second-stage gas-liquid separation tank is sequentially connected with a compressor I and a debutanizer in series, and the bottom of the tank is connected with the debutanizer;
a reflux tank is arranged on the top of the debutanizer, and the top of the reflux tank is sequentially connected with a rich gas desulfurization tower, a rich gas alkaline washing tower, a compressor II, a cooler and an after-cooler; the tank bottom is connected with a liquid hydrocarbon desulfurizing tower, a liquid hydrocarbon sweetening reactor and an after-cooler in sequence; a stable gasoline extraction pipeline is arranged at the bottom of the debutanizer;
the aftercooler is directly connected with the feeding tank through a pipeline;
the top of the feeding tank is connected with a liquefied gas recovery tower, and the bottom of the feeding tank is connected with a demethanizer;
the top of the demethanizer is connected with a liquefied gas recovery tower, and the bottom of the demethanizer is connected with a deethanizer;
a carbon dioxide extraction pipeline is arranged at the top of the deethanizer, the carbon dioxide extraction pipeline is optionally connected with a liquefied gas recovery tower, and the bottom of the deethanizer is connected with a depropanizer;
the upper part of the depropanizing tower is provided with a C3 product extraction pipeline, and the bottom of the depropanizing tower is provided with a C4 product extraction pipeline;
the tower top of the liquefied gas recovery tower is provided with a dry gas extraction pipeline, the tower bottom of the liquefied gas recovery tower is connected with a debutanizer, and the upper part of the liquefied gas recovery tower is provided with an absorbent feeding pipeline.
As a preferable scheme of the invention, the device also comprises a propylene rectifying tower, and the C3 product extraction line is connected with the propylene rectifying tower; and a propylene product extraction pipeline is arranged at the top of the propylene rectifying tower, and a propane product extraction pipeline is arranged at the bottom of the propylene rectifying tower.
As a preferred scheme of the invention, the stable gasoline extraction pipeline is divided into two branches, wherein one branch is used as an absorbent feeding pipeline of a liquefied gas recovery tower; reboilers are arranged at the bottoms of the debutanizer, the demethanizer and the deethanizer; the compressor I is divided into a plurality of sections, and the sections are connected with the debutanizer through liquid phase extraction pipelines.
Compared with the prior art, the invention has the following advantages:
(1) according to the invention, by selecting appropriate process parameters, most of the liquefied gas components are recovered by direct condensation instead of using gasoline as an absorbent, and the gasoline circulation amount is greatly reduced, so that the energy consumption is greatly reduced.
(2) The debutanizer is arranged at the outlet of the compressor I, and separates gasoline, C4 and components below C4 in advance, so that gasoline is not needed to absorb liquefied gas components in the subsequent flow, the consumption of absorbent circulation is saved, meanwhile, gas and liquid at the outlet of a return flow tank at the top of the debutanizer are independently desulfurized, and the material flow does not contain H in the light hydrocarbon separation process2S, the material requirement of the light hydrocarbon separation and recovery system is reduced, and the safety of the process is ensured.
(3) In the invention, because the temperature of the bottoms of the demethanizer and the deethanizer is low, the circulating amount of each component is small, the load of a reboiler at the bottom of the tower is greatly reduced, and the energy is saved.
(4) The top of the fractionating tower adopts two-stage condensation cooling, and most of gasoline is directly separated from a first-stage gas-liquid separation outlet at a higher temperature and is sent to a light gasoline separating tower and a heavy gasoline separating tower, so that the energy consumption required by light gasoline and heavy gasoline separation is reduced, a large amount of gasoline is prevented from being cooled and heated repeatedly, and the investment and the energy consumption are reduced.
Additional features and advantages of the invention will be set forth in the detailed description which follows.
Drawings
The above and other objects, features and advantages of the present invention will become more apparent by describing in more detail exemplary embodiments thereof with reference to the attached drawings, in which like reference numerals generally represent like parts throughout.
Fig. 1 shows a process flow diagram for recovering liquefied gas by catalytic cracking light hydrocarbon separation in embodiment 1 of the present invention.
Fig. 2 shows a process flow diagram for recovering liquefied gas by catalytic cracking light hydrocarbon separation in embodiment 2 of the present invention.
Description of reference numerals:
1. a fractionating column; 2. a primary heat exchanger; 3. a first-stage gas-liquid separation tank; 4. a secondary heat exchanger; 5. a secondary gas-liquid separation tank; 6. a first section of a compressor I; 7. a second section of the compressor I; 8. a debutanizer column; 9. a rich gas desulfurization tower; 10. a rich gas caustic wash tower; 11. a liquid hydrocarbon desulfurization tower; 12. a liquid hydrocarbon sweetening reactor; 13. a compressor II; 14. a cooler; 15. an aftercooler; 16. a feed tank; 17. a demethanizer; 18. a deethanizer; 19. a depropanizer; 20. a propylene rectification column; 21. a liquefied gas recovery column;
s1, oil gas from an upstream device; s2, diesel oil; s3, recycling oil; s4, oil slurry; s5, lean amine liquid; s6, an amine-rich solution; s7, alkali liquor; s8, regenerating alkali liquor; s9, dry gas products; s10, propylene products; s11, preparing a carbon four product; s12, propane product; s13, stabilizing the gasoline product; s14, a carbon two product.
Detailed Description
Preferred embodiments of the present invention will be described in more detail below. While the following describes preferred embodiments of the present invention, it should be understood that the present invention may be embodied in various forms and should not be limited by the embodiments set forth herein.
The properties of the feed oil and gas in the following examples are shown in tables 1 and 2:
TABLE 1 flow of high temperature oil and gas at the inlet of the fractionating column
TABLE 2
Example 1
Oil gas recovery device:
the system comprises an oil gas feeding pipeline, a fractionating tower 1, a primary heat exchanger 2, a primary gas-liquid separating tank 3, a secondary heat exchanger 4, a secondary gas-liquid separating tank 5, a compressor I, a debutanizer 8, a rich gas desulfurizing tower 9, a rich gas alkaline washing tower 10, a liquid hydrocarbon desulfurizing tower 11, a liquid hydrocarbon sweetening reactor 12, a compressor II 13, a cooler 14, an after cooler 15, a feeding tank 16, a demethanizer 17, a deethanizer 18, a depropanizer 19, a propylene rectifying tower 20 and a liquefied gas recovery tower 21;
wherein, the oil gas feed pipeline is connected with the fractionating tower 1,
the top of the fractionating tower 1 is provided with a primary heat exchanger 2, a primary gas-liquid separation tank 3, a secondary heat exchanger 4 and a secondary gas-liquid separation tank 5, a diesel oil extraction pipeline and a recycle oil extraction pipeline are arranged on the lateral line, and an oil slurry extraction pipeline is arranged at the bottom of the fractionating tower; the top of the fractionating tower 1 is sequentially connected with a primary heat exchanger 2 and a primary gas-liquid separation tank 3 in series, the top of the primary gas-liquid separation tank 3 is sequentially connected with a secondary heat exchanger 4 and a secondary gas-liquid separation tank 5 in series, and the bottom of the fractionating tower 1 is respectively connected with a debutanizer 8; the top of the second-stage gas-liquid separation tank 5 is sequentially connected with a compressor I and a debutanizer 8 in series, and the bottom of the tank is connected with the debutanizer 8;
a reflux tank is arranged at the top of the debutanizer 8, and the top of the reflux tank is sequentially connected with a rich gas desulfurization tower 9, a rich gas alkaline washing tower 10, a compressor II 13, a cooler 14 and an aftercooler 15; the tank bottom is connected with a liquid hydrocarbon desulfurizing tower 11, a liquid hydrocarbon sweetening reactor 12 and an after-cooler 15 in sequence; a stable gasoline extraction pipeline is arranged at the bottom of the debutanizer 8;
the aftercooler 15 is directly connected with the feeding tank 16 through a pipeline;
the top of the feed tank 16 is connected with a liquefied gas recovery tower 21, and the bottom of the tank is connected with a demethanizer 17;
the top of the demethanizer 17 is connected with a liquefied gas recovery tower 21, the bottom of the demethanizer is connected with a deethanizer 18, and the bottom of the tower is provided with a reboiler;
the top of the deethanizer 18 is connected with a liquefied gas recovery tower 21, the bottom of the deethanizer is connected with a depropanizer 19, and the bottom of the tower is provided with a reboiler;
the upper part of the depropanizing tower 19 is connected with the propylene rectifying tower 20, and the bottom of the tower is provided with a C4 product extraction pipeline;
a propylene product extraction pipeline is arranged at the top of the propylene rectifying tower 20, and a propane product extraction pipeline is arranged at the bottom of the tower;
the tower top of the liquefied gas recovery tower 21 is provided with a dry gas extraction pipeline, the tower bottom is connected with the debutanizer 8, the upper part of the liquefied gas recovery tower 21 is provided with an absorbent feeding pipeline, and the absorbent feeding pipeline is connected with one of the stable gasoline extraction pipelines.
The oil gas recovery is carried out by adopting the process flow shown in figure 1, and the specific process comprises the following steps:
(1) separation: oil gas (product composition is shown in table 1) from an outlet of a reactor of a catalytic cracking upstream device is sent to a fractionating tower for separation, oil slurry S4, diesel oil S2 and recycle oil S3 are respectively extracted from the bottom and a lateral line of the fractionating tower 1, gas phase at the top of the tower is cooled and then sent to a first-stage gas-liquid separation tank 3, gas phase at the top of the tank is condensed again and then sent to a second-stage gas-liquid separation tank 5, liquid phase part at the bottom of the tank is sent back to the top of the fractionating tower 1, and the rest part of the gas phase is sent to a debutanizer 8; the gas phase at the top of the secondary gas-liquid separation tank 5 is compressed and then sent to a debutanizer 8, and the liquid phase at the bottom of the tank is boosted and then sent to the debutanizer 8;
(2) removing butane: the gas phase and the liquid phase from the step (1) enter a debutanizer 8, the gas phase distilled from the top of the debutanizer 8 enters a reflux tank at the top of the tower through condensation to separate a gas phase and a liquid phase, then impurities are respectively removed, part of the liquid phase at the bottom of the debutanizer is taken as a stable gasoline product S13 to be extracted, and the rest part of the liquid phase is taken as an absorbent to be sent to a liquefied gas recovery tower 21;
(3) gas-phase impurity removal: the gas phase on the top of the reflux tank at the top of the debutanizer 8 is sequentially subjected to H removal in a rich gas desulfurization tower 9 by taking lean amine liquid S5 as an absorbent2S and CO2In the rich gas caustic tower 10, mercaptan is removed by taking alkali liquor S7 as an absorbent, and then the rich gas caustic tower is pressurized and cooled and then is sent to an aftercooler 15;
(4) liquid phase impurity removal: the liquid phase at the bottom of the reflux tank at the top of the debutanizer 8 is sequentially removed with H in the liquid hydrocarbon desulfurizing tower 112S and CO2After mercaptan is removed in the liquid hydrocarbon mercaptan removal reactor 12, the liquid hydrocarbon mercaptan removed is sent to an aftercooler 15;
(5) post-cooling: the gas phase and the liquid phase are preliminarily mixed and cooled in an aftercooler 15 and then are sent to a feeding tank 16;
(6) feeding: after the mixture flow from the after-cooler 15 is mixed and gas-liquid balanced in the feeding tank 16, the gas phase at the top of the tank is sent to a liquefied gas recovery tower 21, and the liquid phase at the bottom of the tank is sent to a demethanizer 17;
(7) demethanization: the liquid phase from the bottom of the feed tank 16 removes methane in the demethanizer 17, and simultaneously removes a small part of components with the carbon number of 2 and more than 2, the gas phase at the top of the demethanizer 17 is sent to a liquefied gas recovery tower 21, and the liquid phase at the bottom of the demethanizer is sent to a deethanizer 18;
(8) deethanizing: separating C2 components from the liquid phase at the bottom of the demethanizer 17 in a deethanizer, collecting the separated mixed C2 components from the top of the deethanizer 18, sending the components to a liquefied gas recovery tower 21, and sending the liquid phase components with C3 and C3 at the bottom of the deethanizer 19;
(9) depropanizing: the liquid phase component from the tower bottom of the deethanizer 18 is further separated in the depropanizer 19, the separated C3 component is extracted from the upper part of the depropanizer 19 and then sent to the propylene rectifying tower 20, and the liquid phase at the tower bottom is extracted as a C-IV product S11;
(10) and (3) recovering liquefied gas: in the liquefied gas recovery tower 21, stabilized gasoline is used as an absorbent to absorb liquefied gas components in gas phase in the tower, the gas phase at the top of the liquefied gas recovery tower 21 is extracted as a dry gas product S9, and the liquid phase at the bottom of the tower returns to the debutanizer 8.
(11) And (3) propylene rectification: and (3) sending the carbon product extracted from the upper part of the depropanizing tower 19 to a propylene rectifying tower 20 for further rectification, wherein the gas phase at the top of the propylene rectifying tower 20 is extracted as a propylene product S10, and the liquid phase at the bottom of the propylene rectifying tower is extracted as a propane product S12.
The properties of the product isolated by the above process are shown in tables 3 and 4.
TABLE 3
TABLE 4 Properties of gasoline, Diesel and slurry products
Example 2
The oil gas recovery is carried out by adopting the process flow shown in figure 2, and only the difference from the example 1 is that:
(8) deethanizing: the liquid phase from the bottom of the demethanizer 17 is further separated into C2 components in the deethanizer 18, the separated mixed C2 component is extracted from the top of the deethanizer 18, a carbon dioxide product S14 is obtained as a byproduct, and the liquid phase components at the bottom of the deethanizer 19 containing C3 and C3 are distributed.
The light hydrocarbons in the catalytic cracking reaction were separated by the above-described method, and the composition and properties of each product were separated as shown in tables 6 and 7.
TABLE 6
TABLE 7 Properties of gasoline, Diesel and slurry products
From the above, the operation conditions of the invention are mild, and the method can realize the high-efficiency separation and recovery of the carbon three and the carbon four components, and simultaneously, the light hydrocarbon recovery system does not contain H2S, the material requirement of the light hydrocarbon recovery system is reduced, and the operation is safer. In addition, as can be seen from example 2, the present invention can also obtain a carbon dioxide product as a byproduct, and the recovery rate of the carbon dioxide product is 50 to 60%.
Having described embodiments of the present invention, the foregoing description is intended to be exemplary, not exhaustive, and not limited to the embodiments disclosed. Many modifications and variations will be apparent to those of ordinary skill in the art without departing from the scope and spirit of the described embodiments.
Claims (8)
1. A method of oil and gas recovery, the method comprising:
(1) separation: oil gas from an upstream device is sent to a fractionating tower for separation, oil slurry, diesel oil and recycle oil are respectively extracted from the bottom and a lateral line of the fractionating tower, gas phase at the top of the tower is sent to a first-stage gas-liquid separation tank after being cooled, gas phase at the top of the tank is sent to a second-stage gas-liquid separation tank after being condensed again, liquid phase part at the bottom of the tank is sent to the top of the fractionating tower, and the rest part of the liquid phase part is sent to a debutanizer; compressing the gas phase at the top of the secondary gas-liquid separation tank, and then sending the compressed gas phase to a debutanizer, boosting the pressure of the liquid phase at the bottom of the tank, and then sending the liquid phase to the debutanizer;
(2) removing butane: the gas phase and the liquid phase from the step (1) enter a debutanizer, the gas phase distilled from the top of the debutanizer enters a reflux tank at the top of the tower through condensation to separate a gas phase and a liquid phase, then impurities are respectively removed, and at least part of the liquid phase at the bottom of the debutanizer is taken as a stable gasoline product to be extracted;
(3) gas phaseRemoving impurities: gas phase on the top of a reflux tank at the top of the debutanizer tower is sequentially subjected to H removal in a rich gas desulfurization tower by taking lean amine liquid as an absorbent2S and CO2Removing mercaptan in a rich gas alkaline tower by taking alkali liquor as an absorbent, then pressurizing and cooling the rich gas alkaline tower, and then sending the rich gas alkaline tower to a post cooler;
(4) liquid phase impurity removal: removing H from the liquid phase at the bottom of the reflux tank at the top of the debutanizer in turn in a liquid hydrocarbon desulfurization tower2S and CO2After mercaptan is removed in the liquid hydrocarbon mercaptan removal reactor, the liquid hydrocarbon mercaptan removed is sent to a aftercooler;
(5) post-cooling: the gas phase and the liquid phase are preliminarily mixed and cooled in a postcooler and then are sent to a feeding tank;
(6) feeding: after the mixture flow from the aftercooler is mixed and gas-liquid balanced in a feeding tank, the gas phase at the top of the tank is sent to a liquefied gas recovery tower, and the liquid phase at the bottom of the tank is sent to a demethanizer;
(7) demethanization: removing methane from the liquid phase at the bottom of the feed tank in a demethanizer, simultaneously removing a small part of components with the content of C2 and above C2, sending the gas phase at the top of the demethanizer to a liquefied gas recovery tower, and sending the liquid phase at the bottom of the demethanizer to a deethanizer;
(8) deethanizing: separating C2 component from the liquid phase at the bottom of the demethanizer in a deethanizer, collecting the separated mixed C2 component from the top of the deethanizer or sending the component to a liquefied gas recovery tower, and sending the liquid phase components with C3 and above C3 at the bottom of the deethanizer to a depropanizer;
(9) depropanizing: the liquid phase component from the bottom of the deethanizer is further separated in the depropanizer,
the separated C3 component is extracted as a carbon three product from the upper part of the depropanizing tower, and is extracted as a carbon four product from the bottom of the depropanizing tower;
(10) and (3) recovering liquefied gas: in the liquefied gas recovery tower, stabilized gasoline is used as an absorbent to absorb liquefied gas components in a gas phase in the tower, the gas phase at the top of the liquefied gas recovery tower is extracted as a dry gas product, and a liquid phase at the bottom of the liquefied gas recovery tower returns to the debutanizer;
(11) and (3) propylene rectification: and (3) sending the carbon product extracted from the upper part of the depropanizing tower to a propylene rectifying tower for further rectification, wherein the gas phase at the top of the propylene rectifying tower is extracted as a propylene product, and the liquid phase at the bottom of the propylene rectifying tower is extracted as a propane product.
2. The method of claim 1, wherein the hydrocarbons of the upstream plant contain H2The device comprises C1-C4 light hydrocarbon, gasoline, diesel oil and heavy oil, wherein the upstream device is at least one of catalytic cracking, catalytic cracking and delayed coking.
3. The method of claim 1,
the operation temperature of the top of the fractionating tower is 100-140 ℃, and the pressure is 0.1-0.35 MPaG;
the operation temperature of the primary gas-liquid separation tank is 60-80 ℃, and the pressure is 0.07-0.32 MPaG; the operation temperature of the secondary gas-liquid separation tank is 35-50 ℃, and the pressure is 0.03-0.28 MPaG;
the operation temperature of the top of the debutanizer is 55-85 ℃, and the operation pressure is 1.0-1.3 MPaG; the operation temperature of the tower bottom is 160-210 ℃, and the temperature of the reflux tank at the tower top of the debutanizer is 35-45 ℃;
the operation temperature of the rich gas desulfurization tower is 35-45 ℃, and the operation pressure is 0.95-1.25 MPaG;
the operating temperature of the liquid hydrocarbon desulfurization tower is 35-45 ℃, and the operating pressure is 2.2-3.0 MPaG;
the operating temperature of the feeding tank is 5-20 ℃, and the operating pressure is 2.0-2.8 MPaG.
4. The method according to claim 1, wherein the temperature of the top of the demethanizer is 10-30 ℃, the pressure is 2.2-3.0 MPaG, and the temperature of the bottom of the demethanizer is 60-100 ℃; the temperature of the top of the deethanizer is 5-20 ℃, the pressure is 2.6-3.2 MPaG, and the temperature of the bottom of the deethanizer is 95-120 ℃; the tower top temperature of the depropanizing tower is 50-65 ℃, the pressure is 1.6-2.0 MPaG, and the tower bottom temperature is 95-120 ℃.
5. The method according to claim 1, wherein the liquefied gas recovery tower has a temperature of 5 to 20 ℃ and a pressure of 2.0 to 2.8 MPaG; the absorbent is a stable gasoline product extracted from the bottom of the debutanizer, and does not need to be supplemented from the outside of the system.
6. The method according to claim 1, wherein the temperature of the propylene rectification column is 45-60 ℃ and the pressure is 1.7-2.0 MPaG.
7. An apparatus for use in the method of any one of claims 1 to 6, the apparatus comprising: the system comprises an oil gas feeding pipeline, a fractionating tower, a primary heat exchanger, a primary gas-liquid separating tank, a secondary heat exchanger, a secondary gas-liquid separating tank, a compressor I, a debutanizer, a rich gas desulfurization tower, a rich gas alkaline washing tower, a liquid hydrocarbon desulfurization tower, a liquid hydrocarbon sweetening reactor, a compressor II, a cooler, an after cooler, a feeding tank, a demethanizer, a deethanizer, a depropanizer, a liquefied gas recovery tower and a propylene rectifying tower;
wherein, the oil gas feed pipeline is connected with the fractionating tower,
the top of the fractionating tower is provided with a first-stage heat exchanger, a first-stage gas-liquid separation tank, a second-stage heat exchanger and a second-stage gas-liquid separation tank, a diesel oil extraction pipeline and a recycle oil extraction pipeline are arranged on the lateral line, and an oil slurry extraction pipeline is arranged at the bottom of the fractionating tower; the top of the fractionating tower is sequentially connected with a first-stage heat exchanger and a first-stage gas-liquid separation tank in series, the top of the first-stage gas-liquid separation tank is sequentially connected with a second-stage heat exchanger and a second-stage gas-liquid separation tank in series, and the bottom of the fractionating tower is respectively connected with the fractionating tower and the debutanizer; the top of the second-stage gas-liquid separation tank is sequentially connected with a compressor I and a debutanizer in series, and the bottom of the tank is connected with the debutanizer;
a reflux tank is arranged on the top of the debutanizer, and the top of the reflux tank is sequentially connected with a rich gas desulfurization tower, a rich gas alkaline washing tower, a compressor II, a cooler and an after-cooler; the tank bottom is connected with a liquid hydrocarbon desulfurizing tower, a liquid hydrocarbon sweetening reactor and an after-cooler in sequence; a stable gasoline extraction pipeline is arranged at the bottom of the debutanizer;
the aftercooler is directly connected with the feeding tank through a pipeline;
the top of the feeding tank is connected with a liquefied gas recovery tower, and the bottom of the feeding tank is connected with a demethanizer;
the top of the demethanizer is connected with a liquefied gas recovery tower, and the bottom of the demethanizer is connected with a deethanizer;
a carbon dioxide extraction pipeline is arranged at the top of the deethanizer, the carbon dioxide extraction pipeline is optionally connected with a liquefied gas recovery tower, and the bottom of the deethanizer is connected with a depropanizer;
the upper part of the depropanizing tower is provided with a C3 product extraction pipeline, and the bottom of the depropanizing tower is provided with a C4 product extraction pipeline;
a dry gas extraction pipeline is arranged at the top of the liquefied gas recovery tower, the bottom of the liquefied gas recovery tower is connected with a debutanizer, and an absorbent feeding pipeline is arranged at the upper part of the liquefied gas recovery tower;
the C3 product extraction pipeline is connected with the propylene rectifying tower; and a propylene product extraction pipeline is arranged at the top of the propylene rectifying tower, and a propane product extraction pipeline is arranged at the bottom of the propylene rectifying tower.
8. The apparatus of claim 7, wherein the stabilized gasoline production line is bifurcated, one of which serves as an absorbent feed line to a liquefied gas recovery column;
reboilers are arranged at the bottoms of the debutanizer, the demethanizer and the deethanizer;
the compressor I is divided into a plurality of sections, and the sections are connected with the debutanizer through liquid phase extraction pipelines.
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| US5015364A (en) * | 1989-06-21 | 1991-05-14 | Mobil Oil Corporation | Method and means for refinery gas plant operation |
| CN102382680A (en) * | 2010-08-30 | 2012-03-21 | 中国石油化工股份有限公司 | Combined technology of catalytic cracking absorbing stabilizing system and C3 intercooling oil absorption |
| CN102503757A (en) * | 2011-09-20 | 2012-06-20 | 王松汉 | Process flow for separating low-carbon hydrocarbons and separating gas during production of olefins (M-OS/MTO) from methanol |
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