CN112760126B - Oil-gas separation and recovery device and method - Google Patents
Oil-gas separation and recovery device and method Download PDFInfo
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- CN112760126B CN112760126B CN201911061389.XA CN201911061389A CN112760126B CN 112760126 B CN112760126 B CN 112760126B CN 201911061389 A CN201911061389 A CN 201911061389A CN 112760126 B CN112760126 B CN 112760126B
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- C—CHEMISTRY; METALLURGY
- 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
Abstract
The invention belongs to the field of chemical industry, and particularly disclosesThe invention relates to an oil-gas separation and recovery device and a method, wherein before light hydrocarbon separation, gasoline, C4 and components below C4 are separated in advance, so that gasoline is not required to be adopted in the subsequent flow to absorb liquefied gas components, the consumption of absorbent circulation is saved, meanwhile, the gas at the outlet of a debutanizer is desulfurized, and the material flow does not contain H in the light hydrocarbon separation process2S, the material requirement of a light hydrocarbon separation and recovery system is reduced, and H is reduced2The risk possibly brought by S leakage ensures the safety of the whole process; meanwhile, the invention has simple process flow, mild operation condition and less energy consumption.
Description
Technical Field
The invention belongs to the field of oil refining and chemical engineering, and particularly relates to an oil-gas separation and recovery device and method in processes with high gas yield, such as catalytic cracking, delayed coking and the like.
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 under a 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, then the light components of carbon, etc. are desorbed under proper conditions, and after cooling, the light components are returned to the absorption tower. Thus, the carbon two and the carbon three are separated by adopting an absorption and desorption method under a mild operation condition, the carbon two and the carbon three are prevented from being separated by adopting a rectification method (the pressure is high, the temperature is low, refrigeration is required), and the investment and the energy consumption are reduced; the cost is that the top gas of the desorption tower contains a certain amount of heavy components such as liquefied gas and the like besides carbon dioxide, and the desorbed 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.
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, the liquefied gas components are absorbed at the normal temperature of 40 ℃, refrigeration is not carried out, and the gasoline circulation amount is large in order to ensure the liquefied gas recovery rate.
(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.
Disclosure of Invention
The invention aims to provide a device and a method for separating and recovering liquefied gas from oil gas, which have simple process flow and mild operation conditions, can realize the high-efficiency separation and recovery of C three and C four components, and does not contain H in the recovery process2S, the material requirement of the light hydrocarbon recovery system is reduced, and the method is safer.
In order to achieve the above object, the present invention provides a method for oil-gas separation and recovery, comprising:
(1) gas-liquid separation: oil gas from an upstream device is condensed and cooled and then sent to a gas-liquid separation tank for gas-liquid separation, a liquid phase at the bottom of the tank is pressurized and then sent to a debutanizer, and a gas phase at the top of the tank is compressed and then sent 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 the gas phase and the liquid phase are respectively sent to impurity removal, 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 CO2Removing mercaptan in a rich gas alkaline tower by taking alkali liquor as an absorbent, cooling, and then sending 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) and (3) 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 gas-liquid equilibrium of the material flow from the after-cooler is carried out in the feeding tank, the gas phase at the top of the tank is sent to the absorption tower, and the liquid phase at the bottom of the tank is sent to the demethanizer;
(7) absorption: in the absorption tower, mixed C4 is used as an absorbent to absorb components above C3 and C3 in a gas phase from the top of a feed tank, meanwhile, light components below C2 and C2 are absorbed together, the gas phase at the top of the absorption tower is sent to a downstream device, and a liquid phase at the bottom of the absorption tower returns to an aftercooler;
(6) demethanization: further separating methane hydrogen components from the liquid phase at the bottom of the feed tank in the demethanizer, extracting the separated methane hydrogen from the top of the deethanizer or returning the separated methane hydrogen to an aftercooler, and sending the liquid phase components at the bottom of the deethanizer;
(7) deethanizing: further separating C2 components from the liquid phase at the bottom of the demethanizer in a deethanizer, extracting the separated mixed C2 components from the top of the deethanizer or returning the mixed C2 components to an aftercooler, and delivering the liquid phase components at the bottom of the deethanizer, wherein the liquid phase components are C3 and more than C3;
(8) depropanizing: the liquid phase component from the bottom of the deethanizer is further separated in the depropanizer, the separated C3 component is extracted from the top of the depropanizer, at least part of the bottom component is sent to the absorption tower as the mixed C4 absorbent, and the rest is extracted as the mixed C4 product.
As a preferable embodiment of the further separation of the C3 component, the method further comprises: (9) and (3) propylene rectification: and (3) sending the C3 component extracted from the depropanizing tower into a propylene rectifying tower for further rectification, extracting a gas phase at the top of the propylene rectifying tower as a propylene product, and extracting a liquid phase at the bottom of the propylene rectifying tower as a propane product, wherein the temperature at the top of the propylene rectifying tower is preferably 45-50 ℃, the pressure is 1.7-2.0 MPaG, and the temperature at the bottom of the propylene rectifying tower is 55-60 ℃.
As a preferable scheme for further recovering the components C4 and C4, the method further comprises the following steps: (10) and (3) recovering the absorbent: the gas phase from the top of the absorption tower absorbs components with the concentration of C4 and above C4 in the gas phase from the top of the absorption tower by taking stable gasoline from debutanization as an absorbent in an absorbent recovery tower, simultaneously absorbs part of the components with the concentration of C2/C3, the gas phase from the top of the absorption tower is taken out as dry gas, and the liquid phase at the bottom of the absorption tower returns to a debutanizer or returns to a catalytic cracking unit fractionating tower as top circulation, and further preferably, the pressure of the absorbent recovery tower is 0.85-1.35 MPaG, and the temperature is 5-25 ℃.
The invention has wide application range, and the oil gas (including H) in the common processes with higher gas yield such as catalytic cracking, delayed coking and the like in chemical production2C1-C4, gasoline components and minor amounts of non-hydrocarbon components) can be separated and recovered using the apparatus of the present invention.
As a preferable scheme of the invention, in order to avoid the need of using a large amount of gasoline for cyclic absorption in the prior art liquefied gas recovery, the invention firstly uses a debutanizer to separate gasoline from components with the carbon number of C4 and the carbon number of below C4, wherein the temperature at the top of the debutanizer is 55-85 ℃, the pressure at the top of the debutanizer is 1.0-1.5 MPaG, and the temperature at the bottom of the debutanizer is 160-210 ℃.
As a preferred scheme of the invention, in order to meet the requirements of related product recovery, gas-liquid phase impurity removal is required to be carried out on the overhead stream of the debutanizer before the overhead stream is subjected to next separation, and the gas-liquid phase impurity removal mainly comprises amine elution H2S and alkali washing to remove mercaptan, preferably, the temperature of gas phase impurity removal is 35-45 ℃, and the pressure is 0.95-1.45 MPaG; the temperature of the liquid phase impurity removal is 35-45 ℃, and the pressure is 1.6-2.2 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 20ppmw, CO2The removal efficiency can reach 90-99 wt%, and CO in material flow entering the alkaline washing mercaptan removal reactor is effectively reduced2And further reducing the consumption of alkali liquor. After the gas-liquid phase is washed out from amine, H can be further washed by alkali2S is reduced to less than 10ppmw, CO2To below 200 ppmw.
As a preferable scheme of the invention, the temperature of the feeding tank is 5-25 ℃, and the pressure is 0.9-1.4 MPaG; the pressure of the absorption tower is 0.85-1.35 MPaG, and the temperature is 5-25 ℃.
Because the main recovery target of the invention is C3/C4 components, and propylene with the purity not lower than 99.6 v% is further separated, according to the principle that the saturated vapor pressure of the C3/C4 groups is lower, under the process operation condition adopted by the invention, a large part of C3/C4 components can be condensed by directly adopting one-time gas-liquid separation, then demethanization, deethanization and depropanization processes are carried out on the condensate in sequence, and finally propane and propylene products can be obtained by further rectification.
As a preferred embodiment of the present invention, when it is desired to recover the carbon dioxide product, the carbon dioxide product obtained from the top of the deethanizer can be directly taken out, subjected to impurity removal and sent to a downstream ethylene plant for further recovery, the carbon dioxide product being mainly ethylene and ethane and containing about 20 v% propylene, wherein the recovery of the carbon dioxide component is 50-60 wt%.
As a preferable scheme of the invention, the circulating carbon four is used as an absorbent, the carbon four components circulate among the absorption tower, the deethanization tower and the depropanization tower, and the boiling point of the carbon four components is low, so that the temperature of the bottoms of the demethanizer, the deethanizer and the depropanization tower is low, the load of a reboiler at the bottom of the tower is reduced, and the energy is saved, wherein the temperature at the top of the demethanizer is 10-35 ℃, the pressure is 1.2-1.7 MPaG, and the temperature at the bottom of the tower is 50-80 ℃; the temperature of the top of the deethanizer is 5-25 ℃, the pressure is 2.0-3.2 MPaG, and the temperature of the bottom of the deethanizer is 60-110 ℃; the tower top temperature of the depropanizing tower is 45-60 ℃, the pressure is 1.6-2.0 MPaG, and the tower bottom temperature is 85-110 ℃.
In the invention, the demethanizer is only provided with a stripping section and is not provided with a rectifying section, the tower top is not provided with a condenser, and the liquid phase from the upstream gas-liquid separation tank directly enters the first tower plate at the tower top of the demethanizer, so that the consumption of the whole process on cold energy is reduced.
In the invention, the deethanizer is provided with a rectifying section and a stripping section simultaneously, so that the propylene and heavier components taken away from the gas at the top of the deethanizer are reduced as much as possible, and the circulating amount of the propylene and heavier components is reduced, thereby reducing the flow of the circulating C4 and reducing the energy consumption.
In another aspect, the present invention provides an apparatus for oil-gas separation and recovery, comprising: the system comprises an oil gas feeding pipeline, a gas-liquid separation tank, a compressor, a debutanizer, a rich gas desulfurization tower, a rich gas alkaline washing tower, a liquid hydrocarbon desulfurization tower, a liquid hydrocarbon sweetening reactor, a cooler, an after cooler, a feeding tank, an absorption tower, a demethanizer, a deethanizer and a depropanizer;
wherein, the oil gas feed pipeline is connected with the inlet of the gas-liquid separation tank, the top of the gas-liquid separation tank is sequentially connected with the compressor and the debutanizer, and the bottom of the gas-liquid separation 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 cooler, an after cooler and a feeding tank; the tank bottom is sequentially connected with a liquid hydrocarbon desulfurizing tower, a liquid hydrocarbon sweetening reactor, an after cooler and a feeding tank; a stable gasoline extraction pipeline is arranged at the bottom of the debutanizer;
the top of the feeding tank is connected with the absorption tower, and the bottom of the feeding tank is connected with the demethanizer;
the top of the absorption tower is connected with a downstream device, the bottom of the absorption tower is connected with an aftercooler, and the upper part of the absorption tower is provided with a mixed C4 absorbent feeding pipeline;
the top of the demethanizer is connected with the aftercooler, and the bottom of the demethanizer is connected with the deethanizer;
a carbon dioxide extraction pipeline is arranged at the top of the deethanizer, the carbon dioxide extraction pipeline is optionally connected with an aftercooler, and the bottom of the deethanizer is connected with a depropanizer;
a mixed C3 product extraction pipeline is arranged at the upper part of the depropanizing tower, a mixed C4 product extraction pipeline is arranged at the bottom of the depropanizing tower, the mixed C4 product extraction pipeline is divided into two branches, and one branch is used as a mixed C4 absorbent feeding pipeline;
as a preferred embodiment of the present invention, the downstream apparatus comprises a propylene rectification column; the mixed 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.
As a preferred aspect of the present invention, the downstream apparatus comprises an absorbent recovery column; the top of the absorbent recovery tower is provided with a dry gas extraction pipeline, the bottom of the absorbent recovery tower is connected with a debutanizer, the upper part of the absorbent recovery tower is provided with a stable gasoline absorbent feeding pipeline, the stable gasoline product extraction pipeline of the debutanizer is divided into two branches, and one branch is used as the stable gasoline absorbent feeding pipeline; or a dry gas extraction pipeline is arranged at the top of the absorbent recovery tower, the bottom of the absorbent recovery tower is connected with the catalytic cracking unit, and a stable gasoline absorbent feeding pipeline is arranged at the upper part of the absorbent recovery tower and is connected with a stable gasoline extraction pipeline of the catalytic cracking unit.
As a preferable scheme of the invention, a reboiler is arranged at the bottom of the debutanizer; the compressor can be divided into a plurality of sections, and an intersegment liquid phase extraction pipeline is connected with the debutanizer.
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) In the invention, before the light hydrocarbon separation, the gasoline, the C4 and the components below C4 are separated in advance, 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 hydrocarbon and the liquid hydrocarbon at the outlet 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, the circulating C4 is used as the absorbent, so that the temperature of the bottoms of the demethanizer and the deethanizer is low, the circulating amount of C4 is small, the load of a reboiler at the bottom of the tower is reduced, and the energy is saved.
(4) The invention adopts the process flow of demethanization and deethanization for the material flow at the bottom of the feed tank, the gas phase flow at the top of the demethanizer and the deethanizer is low, the gas returned to the absorption tower is small, the carbon four-cycle quantity can be effectively reduced, and the energy consumption is low.
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 the separation and recovery of catalytically cracked oil and gas in example 1 of the present invention.
FIG. 2 shows a process flow diagram for the separation and recovery of catalytically cracked oil and gas in example 2 of the present invention.
Description of reference numerals:
1. a gas-liquid separation tank; 2. a compressor section; 3. a second compressor section; 4. a debutanizer column; 5. a rich gas desulfurization tower; 6. a rich gas caustic wash tower; 7. a liquid hydrocarbon desulfurization tower; 8. a liquid hydrocarbon sweetening reactor; 9. a cooler; 10. an aftercooler; 11. a feed tank; 12. an absorption tower; 13. a demethanizer; 14. a deethanizer; 15. a depropanizer; 16. a propylene rectification column; 17. an absorbent recovery column;
s1, oil gas from an upstream device; s2, crude gasoline; s3, lean amine liquid; s4, an amine-rich solution; s5, alkali liquor; s6, alkali liquor to be regenerated; s7, a carbon four absorbent; s8, preparing a carbon four product; s9, dry gas; s10, propylene products; s11, propane product; s12, stabilizing gasoline; s13, 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 table 1, and the properties of the C5+ component in the oil and gas are shown in table 2:
TABLE 1
TABLE 2
| Item | Numerical value |
| Density, 20 deg.C | 0.8167 |
| En-type distillation (D-86) and C | Percent distilled off, v% |
| 0 | 42 |
| 10 | 91 |
| 30 | 99 |
| 50 | 129 |
| 70 | 145 |
| 90 | 162 |
| 100 | 187 |
Example 1
An apparatus for oil and gas separation recovery comprising: the system comprises an oil gas feeding pipeline, a gas-liquid separation tank 1, a compressor, a debutanizer 4, a rich gas desulfurizing tower 5, a rich gas alkaline washing tower 6, a liquid hydrocarbon desulfurizing tower 7, a liquid hydrocarbon sweetening reactor 8, a cooler 9, an after cooler 10, a feeding tank 11, an absorption tower 12, a demethanizer 13, a deethanizer 14, a depropanizer 15, a propylene rectifying tower 16 and an absorbent recovery tower 17;
wherein, the oil gas feed pipeline is connected with the inlet of the gas-liquid separation tank 1, the top of the gas-liquid separation tank 1 is sequentially connected with a compressor and a debutanizer 4, and the bottom of the tank is connected with the debutanizer 4;
a reflux tank is arranged at the top of the debutanizer 4, and the top of the reflux tank is sequentially connected with a rich gas desulfurization tower 5, a rich gas alkaline washing tower 6, a cooler 9, an after-cooler 10 and a feeding tank 11; the bottom of the tank is sequentially connected with a liquid hydrocarbon desulfurizing tower 7, a liquid hydrocarbon sweetening reactor 8, an after cooler 10 and a feeding tank 11; a stable gasoline extraction pipeline is arranged at the bottom of the debutanizer 4;
the top of the feed tank 11 is connected with the absorption tower 12, and the bottom of the tank is connected with the demethanizer 13;
the top of the absorption tower 12 is connected with an absorbent recovery tower 17, the bottom of the absorption tower 12 is connected with an aftercooler 10, and the upper part of the absorption tower 12 is provided with a mixed C4 absorbent feeding pipeline;
the top of the absorbent recovery tower 17 is provided with a dry gas extraction pipeline, the bottom of the absorbent recovery tower 17 is connected with the debutanizer 4, the upper part of the absorbent recovery tower 17 is provided with a stable gasoline absorbent feeding pipeline, the stable gasoline product extraction pipeline of the debutanizer 4 is divided into two branches, and one branch is used as the stable gasoline absorbent feeding pipeline;
the top of the demethanizer 13 is connected with the aftercooler 10, and the bottom of the demethanizer is connected with the deethanizer 14;
the top of the deethanizer 14 is connected with the aftercooler 10, and the bottom of the deethanizer 15;
the upper part of the depropanizing tower 15 is connected with the propylene rectifying tower 16, the bottom of the depropanizing tower is provided with a mixed C4 product extraction pipeline, the mixed C4 product extraction pipeline is divided into two branches, and one branch is used as a mixed C4 absorbent feeding pipeline;
the upper part of the propylene rectifying tower 16 is provided with a propylene product extraction pipeline, and the bottom of the tower is provided with a propane product extraction pipeline.
The oil-gas separation is carried out by adopting the device, and the separation process is shown in figure 1:
(1) gas-liquid separation: oil gas from an upstream device is condensed and cooled and then sent to a gas-liquid separation tank 1 for gas-liquid separation, a liquid phase at the bottom of the tank is pressurized and then sent to a debutanizer 4, and a gas phase at the top of the tank is compressed and then sent to the debutanizer 4;
(2) removing butane: the gas phase and the liquid phase from the step (1) enter a debutanizer 4, the gas phase distilled from the top of the debutanizer 4 enters a reflux tank at the top of the tower after condensation to separate a gas phase and a liquid phase, then the gas phase and the liquid phase are respectively sent to impurity removal, part of the liquid phase at the bottom of the debutanizer 4 is taken as a stable gasoline product to be extracted, and the rest part of the liquid phase is taken as an absorbent to be sent to an absorbent recovery tower 17; the temperature at the top of the debutanizer is 55-85 ℃, the pressure at the top of the debutanizer is 1.0-1.5 MPaG, and the temperature at the bottom of the debutanizer is 160-210 ℃;
(3) gas-phase impurity removal: the gas phase on the top of the reflux tank at the top of the debutanizer 4 is sequentially subjected to H removal in a rich gas desulfurization tower 5 by taking lean amine liquid S3 as an absorbent2S and CO2In the rich gas caustic tower 6, mercaptan is removed by taking alkali liquor S5 as an absorbent, and the cooled rich gas caustic tower is sent to a aftercooler 10; the temperature of gas phase impurity removal is 35-45 ℃, and the pressure is 0.95-1.45 MPaG;
(5) liquid phase impurity removal: the liquid phase at the bottom of the reflux tank at the top of the debutanizer 4 is sequentially removed with H in the liquid hydrocarbon desulfurizing tower 72S and CO2After mercaptan is removed in the liquid hydrocarbon mercaptan removal reactor 8, the liquid hydrocarbon mercaptan removed is sent to an aftercooler 10; the temperature of liquid phase impurity removal is 35-45 ℃, and the pressure is 1.6-2.2 MPaG;
(5) and (3) cooling: the gas phase and the liquid phase are primarily mixed and cooled in an aftercooler 10 and then are sent to a feeding tank 11;
(6) feeding: after the gas-liquid equilibrium of the material flow from the after-cooler 10 is carried out in the feeding tank 11, the gas phase at the top of the tank is sent to the absorption tower 12, and the liquid phase at the bottom of the tank is sent to the demethanizer 13; the temperature of the feeding tank is 5-25 ℃, and the pressure is 0.9-1.4 MPaG;
(7) absorption: in the absorption tower 12, the mixed C4 is used as an absorbent to absorb components above C3 and C3 in a gas phase from the top of the feed tank 11, meanwhile, light components below C2 and C2 are absorbed together, the gas phase at the top of the absorption tower 12 is sent to an absorbent recovery tower 17, and a liquid phase at the bottom of the absorption tower is returned to an aftercooler 10; the temperature of the absorption tower is 5-25 ℃, and the pressure is 0.85-1.35 MPaG;
(6) demethanization: the liquid phase from the bottom of the feed tank 11 is further separated into methane hydrogen components in a demethanizer 13, the separated methane hydrogen is extracted from the top of a deethanizer 14 and returned to an aftercooler 10, and the liquid phase components at the bottom of the deethanizer 14 are sent to the deethanizer 14; the temperature at the top of the demethanizer is 10-35 ℃, the pressure is 1.2-1.7 MPaG, and the temperature at the bottom of the demethanizer is 50-80 ℃;
(7) deethanizing: the liquid phase at the bottom of the demethanizer 13 is further separated into C2 components in the deethanizer 14, the separated mixed C2 components are extracted from the top of the deethanizer 14 and returned to the aftercooler 10, and the liquid phase components at the bottom of the deethanizer 15 are sent to C3 and above C3; the temperature at the top of the deethanizer is 5-25 ℃, the pressure is 2.0-3.2 MPaG, and the temperature at the bottom of the deethanizer is 60-110 ℃;
(8) depropanizing: the liquid phase component from the bottom of the deethanizer 14 is further separated in the depropanizer 15, the separated C3 component is extracted from the top of the depropanizer 15, at least part of the bottom component is sent to the absorption tower 12 as a mixed C4 absorbent, and the rest is extracted as a mixed C4 product; the temperature at the top of the depropanizing tower is 45-60 ℃, the pressure is 1.6-2.0 MPaG, and the temperature at the bottom of the depropanizing tower is 85-110 ℃;
(9) and (3) propylene rectification: c3 components extracted from the depropanizing tower 15 are sent to the propylene rectifying tower 16 for further rectification, the gas phase at the top of the propylene rectifying tower 16 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 S11; the temperature of the top of the propylene rectifying tower is 45-50 ℃, the pressure is 1.7-2.0 MPaG, and the temperature of the bottom of the propylene rectifying tower is 55-60 ℃;
(10) and (3) recovering the absorbent: the gas phase at the top of the absorption tower 12 absorbs components of C4 and above C4 in the gas phase at the top of the absorption tower 12 in an absorbent recovery tower 17 by taking the stable gasoline from the debutanizer 4 as an absorbent, and absorbs part of the components of C2/C3 at the same time, the gas phase at the top of the absorption tower 17 is taken out as dry gas S9, and the liquid phase at the bottom of the absorption tower is returned to the debutanizer 4; the temperature of the absorbent recovery tower is 5-25 ℃, and the pressure is 0.85-1.35 MPaG.
The light hydrocarbons in the catalytic cracking reaction were separated by the above method, and the composition and properties of each product were separated as shown in tables 3 and 4.
TABLE 3
TABLE 4 gasoline product Properties
Example 2
Light hydrocarbon separation as shown in fig. 2, there is a difference from example 1 in that:
(7) deethanizing: the liquid phase from the bottom of the demethanizer 13 is further separated into C2 components in the deethanizer 14, the separated mixed C2 component is extracted from the top of the deethanizer, a carbon dioxide product S13 is obtained as a byproduct, and the liquid phase components at the bottom of the deethanizer, C3 and above C3, are distributed to the depropanizer 15.
The light hydrocarbons in the catalytic cracking reaction were separated by the above method, and the composition and properties of each product were separated as shown in tables 5 and 6.
TABLE 5
TABLE 6 gasoline product Properties
| Item | Gasoline (gasoline) |
| Flow rate, kg/h | 64252 |
| Density, 20 deg.C | 0.742 |
| Percent distilled off, v% | En type distillation (D-86))，℃ |
| 0 | 44 |
| 10 | 57 |
| 30 | 89 |
| 50 | 107 |
| 70 | 137 |
| 90 | 157 |
| 100 | 182 |
The data in the table show that the process is simple, the operation condition is mild, the energy consumption is low, less equipment is utilized, the recovery of liquefied gas in oil gas of catalytic cracking, catalytic cracking and delayed coking can be realized, wherein the recovery rates of the recovered three-carbon component and four-carbon component are both more than 99 wt%, and the content of C2 in the propylene product obtained by further separation is not more than 200 ppmv. 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 (6)
1. A method for separating and recovering oil gas is characterized by comprising the following steps:
(1) gas-liquid separation: oil gas from an upstream device is condensed and cooled and then sent to a gas-liquid separation tank for gas-liquid separation, a liquid phase at the bottom of the tank is pressurized and then sent to a debutanizer, and a gas phase at the top of the tank is compressed and then sent 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 the gas phase and the liquid phase are respectively sent to impurity removal, 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 CO2Removing mercaptan in a rich gas alkaline tower by taking alkali liquor as an absorbent, cooling, and then sending to a post cooler;
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) and (3) 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 gas-liquid equilibrium of the material flow from the after-cooler is carried out in the feeding tank, the gas phase at the top of the tank is sent to the absorption tower, and the liquid phase at the bottom of the tank is sent to the demethanizer;
(7) absorption: in the absorption tower, mixed C4 is used as an absorbent to absorb components above C3 and C3 in a gas phase from the top of a feed tank, meanwhile, light components below C2 and C2 are absorbed together, the gas phase at the top of the absorption tower is sent to a downstream device, and a liquid phase at the bottom of the absorption tower returns to an aftercooler;
(8) demethanization: further separating light methane components from the liquid phase at the bottom of the feed tank in the demethanizer, extracting the separated light methane components from the top of the demethanizer and returning the light methane components to an aftercooler, and sending the liquid phase components at the bottom of the demethanizer to a deethanizer;
(9) deethanizing: further separating C2 components from the liquid phase at the bottom of the demethanizer in a deethanizer, extracting the separated mixed C2 components from the top of the deethanizer or returning the mixed C2 components to an aftercooler, and delivering the liquid phase components at the bottom of the deethanizer, wherein the liquid phase components are C3 and more than C3;
(10) depropanizing: further separating liquid phase components from the bottom of the deethanizer in a depropanizer, extracting separated C3 components from the top of the depropanizer, sending at least part of the bottom components to an absorption tower as a mixed C4 absorbent, and extracting the rest as a mixed C4 product;
(11) and (3) propylene rectification: c3 components extracted from the depropanizing tower are sent to a propylene rectifying tower for further rectification, 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;
(12) and (3) recovering the absorbent: the gas phase from the top of the absorption tower absorbs components of C4 and above C4 in the gas phase from the top of the absorption tower by taking stable gasoline from debutanization as an absorbent in an absorbent recovery tower, simultaneously absorbs part of the components of C2/C3, the gas phase at the top of the absorbent recovery tower is taken out as dry gas, and the liquid phase at the bottom of the absorption tower returns to the debutanizer or returns to a catalytic cracking unit fractionating tower as top circulation.
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 a catalytic cracking device, a catalytic cracking device and a delayed coking device.
3. The method of claim 1,
the temperature at the top of the debutanizer is 55-85 ℃, the pressure at the top of the debutanizer is 1.0-1.5 MPaG, and the temperature at the bottom of the debutanizer is 160-210 ℃;
the temperature of the gas phase impurity removal is 35-45 ℃, and the pressure is 0.95-1.45 MPaG;
the temperature of the liquid phase impurity removal is 35-45 ℃, and the pressure is 1.6-2.2 MPaG;
the temperature of the feeding tank is 5-25 ℃, and the pressure is 0.9-1.4 MPaG;
the temperature of the absorption tower is 5-25 ℃, and the pressure is 0.85-1.35 MPaG;
the temperature at the top of the demethanizer is 10-35 ℃, the pressure is 1.2-1.7 MPaG, and the temperature at the bottom of the demethanizer is 50-80 ℃; the temperature at the top of the deethanizer is 5-25 ℃, the pressure is 2.0-3.2 MPaG, and the temperature at the bottom of the deethanizer is 60-110 ℃; the temperature at the top of the depropanizing tower is 45-60 ℃, the pressure is 1.6-2.0 MPaG, and the temperature at the bottom of the depropanizing tower is 85-110 ℃.
4. The method according to claim 1, wherein the temperature of the top of the propylene rectifying tower is 45-50 ℃, the pressure is 1.7-2.0 MPaG, and the temperature of the bottom of the propylene rectifying tower is 55-60 ℃.
5. The method according to claim 1, wherein the temperature of the absorbent recovery tower is 5 to 25 ℃ and the pressure is 0.85 to 1.35 MPaG.
6. An apparatus for use in the method of any one of claims 1 to 5, the apparatus comprising: the system comprises an oil gas feeding pipeline, a gas-liquid separation tank, a compressor, a debutanizer, a rich gas desulfurization tower, a rich gas alkaline washing tower, a liquid hydrocarbon desulfurization tower, a liquid hydrocarbon sweetening reactor, a cooler, an after cooler, a feeding tank, an absorption tower, a demethanizer, a deethanizer and a depropanizer;
wherein, the oil gas feed pipeline is connected with the inlet of the gas-liquid separation tank, the top of the gas-liquid separation tank is sequentially connected with the compressor and the debutanizer, and the bottom of the gas-liquid separation 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 cooler, an after cooler and a feeding tank; the tank bottom is sequentially connected with a liquid hydrocarbon desulfurizing tower, a liquid hydrocarbon sweetening reactor, an after cooler and a feeding tank; a stable gasoline extraction pipeline is arranged at the bottom of the debutanizer;
the top of the feeding tank is connected with the absorption tower, and the bottom of the feeding tank is connected with the demethanizer;
the top of the absorption tower is connected with a downstream device, the bottom of the absorption tower is connected with an aftercooler, and the upper part of the absorption tower is provided with a mixed C4 absorbent feeding pipeline;
the top of the demethanizer is connected with the aftercooler, and the bottom of the demethanizer is connected with the deethanizer;
a carbon dioxide extraction pipeline is arranged at the top of the deethanizer, the carbon dioxide extraction pipeline is optionally connected with an aftercooler, and the bottom of the deethanizer is connected with a depropanizer;
a mixed C3 product extraction pipeline is arranged at the upper part of the depropanizing tower, a mixed C4 product extraction pipeline is arranged at the bottom of the depropanizing tower, the mixed C4 product extraction pipeline is divided into two branches, and one branch is used as a mixed C4 absorbent feeding pipeline;
the downstream device comprises a propylene rectifying tower and an absorbent recovery tower;
the mixed C3 product extraction pipeline is connected with the propylene rectifying tower; 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;
the top of the absorbent recovery tower is provided with a dry gas extraction pipeline, the bottom of the absorbent recovery tower is connected with a debutanizer, the upper part of the absorbent recovery tower is provided with a stable gasoline absorbent feeding pipeline, the stable gasoline product extraction pipeline of the debutanizer is divided into two branches, and one branch is used as the stable gasoline absorbent feeding pipeline; alternatively, the first and second electrodes may be,
the top of the absorbent recovery tower is provided with a dry gas extraction pipeline, the bottom of the absorbent recovery tower is connected with the catalytic cracking unit, and the upper part of the absorbent recovery tower is provided with a stable gasoline absorbent feeding pipeline which is connected with a stable gasoline extraction pipeline of the catalytic cracking unit.
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| US5015364A (en) * | 1989-06-21 | 1991-05-14 | Mobil Oil Corporation | Method and means for refinery gas plant operation |
| CN101973831A (en) * | 2010-10-14 | 2011-02-16 | 东华工程科技股份有限公司 | Separation method for producing light olefins from oxygenated chemicals |
| CN106316752A (en) * | 2015-06-24 | 2017-01-11 | 中石化广州工程有限公司 | Separation method for methanol-to-propylene (MTP) reaction product |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| US7273542B2 (en) * | 2003-04-04 | 2007-09-25 | Exxonmobil Chemical Patents Inc. | Process and apparatus for recovering olefins |
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Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5015364A (en) * | 1989-06-21 | 1991-05-14 | Mobil Oil Corporation | Method and means for refinery gas plant operation |
| CN101973831A (en) * | 2010-10-14 | 2011-02-16 | 东华工程科技股份有限公司 | Separation method for producing light olefins from oxygenated chemicals |
| CN106316752A (en) * | 2015-06-24 | 2017-01-11 | 中石化广州工程有限公司 | Separation method for methanol-to-propylene (MTP) reaction product |
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