CN110684575A - Method for removing carbon dioxide in high-pressure natural gas - Google Patents
Method for removing carbon dioxide in high-pressure natural gas Download PDFInfo
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- CN110684575A CN110684575A CN201810739128.8A CN201810739128A CN110684575A CN 110684575 A CN110684575 A CN 110684575A CN 201810739128 A CN201810739128 A CN 201810739128A CN 110684575 A CN110684575 A CN 110684575A
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
- B01D53/34—Chemical or biological purification of waste gases
- B01D53/74—General processes for purification of waste gases; Apparatus or devices specially adapted therefor
- B01D53/77—Liquid phase processes
- B01D53/78—Liquid phase processes with gas-liquid contact
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
- B01D53/34—Chemical or biological purification of waste gases
- B01D53/46—Removing components of defined structure
- B01D53/62—Carbon oxides
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- C—CHEMISTRY; METALLURGY
- C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
- C10L—FUELS NOT OTHERWISE PROVIDED FOR; NATURAL GAS; SYNTHETIC NATURAL GAS OBTAINED BY PROCESSES NOT COVERED BY SUBCLASSES C10G, C10K; LIQUEFIED PETROLEUM GAS; ADDING MATERIALS TO FUELS OR FIRES TO REDUCE SMOKE OR UNDESIRABLE DEPOSITS OR TO FACILITATE SOOT REMOVAL; FIRELIGHTERS
- C10L3/00—Gaseous fuels; Natural gas; Synthetic natural gas obtained by processes not covered by subclass C10G, C10K; Liquefied petroleum gas
- C10L3/06—Natural gas; Synthetic natural gas obtained by processes not covered by C10G, C10K3/02 or C10K3/04
- C10L3/10—Working-up natural gas or synthetic natural gas
- C10L3/101—Removal of contaminants
- C10L3/102—Removal of contaminants of acid contaminants
- C10L3/104—Carbon dioxide
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D2252/00—Absorbents, i.e. solvents and liquid materials for gas absorption
- B01D2252/20—Organic absorbents
- B01D2252/204—Amines
- B01D2252/20405—Monoamines
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02C—CAPTURE, STORAGE, SEQUESTRATION OR DISPOSAL OF GREENHOUSE GASES [GHG]
- Y02C20/00—Capture or disposal of greenhouse gases
- Y02C20/40—Capture or disposal of greenhouse gases of CO2
Abstract
The invention belongs to the technical field of gas purification, and relates to a method for removing carbon dioxide in high-pressure natural gas. The invention provides the process flow of absorption-high-pressure flash evaporation-low-pressure flash evaporation-thermal flash evaporation-absorption, thermal flash steam is simultaneously used as the stripping gas of low-pressure flash evaporation, and the activated MDEA absorption liquid is adopted, so that the energy consumption of the system can be reduced.
Description
Technical Field
The invention belongs to the technical field of gas purification, and relates to a method for removing carbon dioxide in high-pressure natural gas.
Background
The natural gas produced from the formation mostly contains CO2Iso-acid gases, the presence of which can be on dayThe problems of pipeline corrosion, reduction of fuel gas heat value, hydrate generation and the like are caused in the storage, transportation and utilization processes of the natural gas. Therefore, decarburization is a very important step in the pretreatment of natural gas. At present, natural gas decarbonization methods are various, such as an alcohol amine method, a membrane separation method and the like. Among them, the decarburization of N-Methyldiethanolamine (MDEA) is widely applied to industrial production because of its advantages of large treatment capacity, high removal rate and the like.
MDEA and CO2The reaction mechanism of (2) is relatively complicated. From a chemical point of view, tertiary amines such as MDEA contain a tertiary nitrogen atom as the active group, which means that the solution absorbs CO2Only bicarbonate is formed, so that a heating regeneration can be carried out, the steam consumption of which is far higher than that of the primary and secondary amines and CO2The formation of rather stable carbamate salts is low when the regeneration is carried out with heating. Therefore, tertiary amines such as MDEA have been widely used for various CO removal applications2In the process of (1).
Tertiary amines such as MDEA and CO2The reaction pathway is as follows:
（1）
(1) + (2) formula:
（3）。
the reaction is controlled by (1), and the reaction (1) is CO2Hydration reaction, reaction rate constant K at 25 deg.COH=1041／mo1.s，[OH]=10-3～10-5And (mol). Therefore, the reaction (3) is a very slow reaction.
When a small amount of activator R is added to the tertiary amine solution，When NH, CO is absorbed2The process of (a) can be explained by a shuttle mechanism: the activator absorbs CO on the surface of the surface liquid film2Then transfer CO to the liquid phase2The activating agent is regenerated to continuously absorb the diffused CO2Thus the activator becomes CO2Essentially accelerating CO2The mass transfer rate. Absorption of CO2The reaction was carried out according to the following scheme.
(4) The formula of + (5) + (2):
currently, active research on various activators has led to the development of a number of solvents based on N-Methyldiethanolamine (MDEA) in various formulations, typically the aMDEA series of BSAF, the UCARSOL series of DOW, the GAS/SPEC series of INEOS, and the JEFFTREAT series of Huntsman.
In terms of process flow, according to actual working conditions, the single-stage absorption-regeneration tower bottom heat regeneration flow is typically CN107073386A, CN104619395A and the like;
CN105126576A proposes a single-stage absorption-high-pressure flash evaporation-regeneration tower bottom heat regeneration process;
CN1107530C proposes a two-stage absorption-high pressure flash evaporation-low pressure flash evaporation-regeneration tower bottom heat regeneration flow.
The flow reduces the energy consumption of the treatment process as much as possible while meeting the decarburization requirement. However, for high pressure high CO content2The natural gas is treated by the prior art, and still needs higher energy consumption.
Disclosure of Invention
The invention adopts a novel treatment process and a formula type MDEA solution for high-pressure high-CO content2Natural gas CO removal2Compared with the prior art, the energy consumption can be obviously reduced.
The main technical scheme of the invention is as follows: the method for removing the carbon dioxide in the high-pressure natural gas is characterized by comprising the following steps:
in the first step, absorption is carried out to ensure that the high pressure is high and the CO is contained2The natural gas enters an absorption tower to be in countercurrent contact with absorption liquid for absorption, and purified gas and rich liquid rich in carbon dioxide are respectively obtained from the tower top and the tower bottom of the absorption tower;
second, high-pressure flash evaporation is carried out to absorb CO2The absorption liquid is subjected to high-pressure flash evaporation to remove the dissolved methane and other hydrocarbons, and the high-pressure flash evaporation pressure is 0.8-1.2 MPa;
thirdly, low-pressure flash evaporation is carried out, so that the absorption liquid of the hydrocarbon which is flashed off enters low-pressure flash evaporation, and is simultaneously stripped by hot flash steam in a low-pressure flash evaporation tank, wherein the pressure of the low-pressure flash evaporation is normal pressure to 0.08 MPa;
fourthly, heating the absorption liquid after low-pressure flash evaporation; heating the absorption liquid subjected to low-pressure flash evaporation to increase the temperature of the absorption liquid by 3-15 ℃;
fifthly, carrying out thermal flash evaporation to the heated absorption liquid, wherein the pressure of the thermal flash evaporation is 0.01-0.09 MPa;
and sixthly, cooling the absorption liquid from the thermal flash evaporation step, and circulating the absorption liquid back to the absorption tower.
Generally, the temperature of the absorption liquid entering the absorption tower is 60-75 ℃.
The absorption liquid is stripped by hot flash steam while flashing at low pressure, and the pressure of the low-pressure flash is 0.01-0.08 MPa.
And heating the absorption liquid subjected to low-pressure flash evaporation at 5-10 ℃, and then performing thermal flash evaporation again, wherein the thermal flash evaporation pressure is 0.01-0.08 MPa.
The flash gas of the thermal flash evaporation is used as the stripping gas of the low-pressure flash evaporation.
The absorption liquid adopted by the invention is a formula type MDEA solution added with an activating agent, and typical activating agents are diethanol amine, piperazine and derivatives thereof or hindered amine and the like.
The absorption liquid contains a defoaming agent or a corrosion inhibitor.
The particular apparatus involved in the absorption column of the present invention is well known to those skilled in the art.
Compared with the prior art, the method for removing the carbon dioxide from the high-pressure natural gas has the advantages that: only adopting a flash evaporation method to desorb CO absorbed by the absorption liquid2And the flash steam of the thermal flash evaporation is used as the stripping gas of the low-pressure flash evaporation, so that the energy consumption in the treatment process can be further reduced.
Drawings
FIG. 1 is a schematic diagram of a process for removing carbon dioxide from high pressure natural gas according to an embodiment of the present invention.
In the figure: 1-an absorption tower, 2-a high-pressure flash tank, 3-a low-pressure flash tower, 4-a solution heater, 5-a thermal flash tower, 6-a solution cooler, 7-a solution pump and 10-100-pipelines.
Detailed Description
The present invention will be described in detail with reference to examples, but the present invention is not limited to these examples.
The method of the following example refers to figure 1.
Example of implementation
Certain natural gas pressure is 8.0MPa, CO2The content of 20 percent (volume ratio, the same below) and the temperature of 20 ℃ enter from the lower part of the absorption tower 1 and are closely contacted with the hindered amine activated MDEA solution which is arranged below the upper part of the absorption tower to remove CO in the solution2Purification of natural gas CO2Rich in CO, with a content of 2.2%, coming out from the bottom of the absorption column2The absorption liquid enters a high-pressure flash tank 2 after energy is recovered by a hydraulic turbine, the pressure of the high-pressure flash tank is controlled to be 1.2MPa, rich absorption liquid containing most hydrocarbons is flashed out and then enters a low-pressure flash tower 3, the pressure of the low-pressure flash tower 3 is controlled to be 0.03MPa, and the rich absorption liquid is stripped by hot flash steam while being flashed in the low-pressure flash tower. CO from the low pressure flash column 32Can be recycled or emptied, the absorption liquid coming out of the low-pressure flash tower 3 is heated by the heater 4, the temperature is increased by 10 ℃, and the heat consumption of the absorption liquid heater 4 is 300KW/kNm3CO2The heated absorption liquid enters a thermal flash tower 5 to be continuously flashed, the pressure of the thermal flash tower 5 is 0.08MPa, the thermal flash steam coming out from the top of the thermal flash tower 5 enters the lower part of a low-pressure flash tower 3 to be stripped, and the absorption liquid coming out from the thermal flash tower 5 is cooled to 65 ℃ by a cooler 6Recycled to the absorption tower 1 for re-absorption.
Comparative example 1
The natural gas in the first embodiment adopts a single-stage absorption-regeneration tower bottom heat regeneration flow path, and the heat consumption is 640KW/kNm3CO2。
Example two
Certain natural gas pressure is 6.5MPa and CO2The content is 23 percent, the temperature is 40 ℃, by applying the method, hydroxyethyl piperazine is adopted to activate MDEA solution for decarburization, the temperature of barren liquor is 75 ℃, the pressure of high-pressure flash evaporation is 1.2MPa, the pressure of low-pressure flash evaporation is normal pressure, the temperature of heated absorption liquid is increased by 5 ℃, the pressure of a thermal flash tower 5 is 0.01MPa, and CO in purified natural gas is purified2The content is 1.8 percent, and the heat consumption of the absorption liquid heater is 330KW/kNm3CO2。
Comparative example No. two
The natural gas in the second embodiment adopts a single-stage absorption-high-pressure flash evaporation-regeneration tower bottom heat regeneration process, and the heat consumption is 700KW/kNm3CO2。
Example III
Certain natural gas pressure is 4.0MPa, CO2The content is 18 percent, the temperature is 30 ℃, the method is applied, diethanolamine is adopted to activate MDEA solution for decarburization, the temperature of barren liquor is 70 ℃, the pressure of high-pressure flash evaporation is 0.8MPa, the pressure of low-pressure flash evaporation is 0.08MPa, the temperature of heated absorption liquid is raised by 8 ℃, the pressure of a thermal flash tower 5 is 0.09MPa, and CO in purified natural gas is purified2The content is 2.5 percent, and the heat consumption of the absorption liquid heater is 360KW/kNm3CO2。
Comparative example No. three
The natural gas of example three, a two-stage absorption-high pressure flash evaporation-low pressure flash evaporation-regeneration tower bottom heat regeneration flow path is adopted. The regeneration heat consumption is 460KW/kNm3CO2。
Example four
Certain natural gas pressure is 7.0MPa, CO2The content is 25 percent, the temperature is 20 ℃, the method is applied, diethanolamine is adopted to activate MDEA solution for decarburization, the temperature of barren solution is 75 ℃, the pressure of high-pressure flash evaporation is 1.0MPa, and the pressure of low-pressure flash evaporation is0.03MPa, the temperature of the heated absorption liquid rises by 5 ℃, the pressure of the thermal flash tower 5 is 0.04MPa, and CO in the purified natural gas is2The content is 1.3 percent, and the heat consumption of the absorption liquid heater is 310KW/kNm3CO2。
Example five
Certain natural gas pressure is 5.0MPa, CO2The content of the purified natural gas CO is 32 percent, the temperature is 25 ℃, the method is applied, the MDEA solution is activated by adopting the sterically hindered amine for decarburization, the temperature of the barren solution is 60 ℃, the pressure of the high-pressure flash evaporation is 1.0MPa, the pressure of the low-pressure flash evaporation is 0.05MPa, the temperature of the heated absorption liquid is increased by 6 ℃, the pressure of the thermal flash evaporation tower 5 is 0.06MPa, and the purified natural gas CO is purified2The content is 2.3 percent, and the heat consumption of the absorption liquid heater is 400KW/kNm3CO2。
Example six
Certain natural gas pressure is 7.5MPa and CO2The content is 28 percent, the temperature is 20 ℃, the method is applied, hindered amine is adopted to activate MDEA solution for decarburization, the temperature of barren liquor is 65 ℃, the pressure of high-pressure flash evaporation is 1.1MPa, the pressure of low-pressure flash evaporation is 0.02MPa, the temperature of heated absorption liquid is raised by 7 ℃, the pressure of a thermal flash tower 5 is 0.03MPa, and CO in purified natural gas is purified2The content is 1.4 percent, and the heat consumption of the absorption liquid heater is 310KW/kNm3CO2。
Example seven
Certain natural gas pressure is 5.5MPa and CO2The content is 21 percent, the temperature is 30 ℃, the method is applied, diethanolamine is adopted to activate MDEA solution for decarburization, the temperature of barren liquor is 72 ℃, the pressure of high-pressure flash evaporation is 1.1MPa, the pressure of low-pressure flash evaporation is 0.01MPa, the temperature of heated absorption liquid is increased by 9 ℃, the pressure of a thermal flash evaporation tower 5 is 0.02MPa, and CO in purified natural gas is purified2The content is 2.3 percent, and the heat consumption of the absorption liquid heater is 420KW/kNm3CO2。
Claims (8)
1. A method for removing carbon dioxide from high-pressure natural gas is characterized by comprising the following steps:
in the first step, absorption is carried out to ensure that the high pressure is high and the CO is contained2The natural gas enters an absorption tower to be in countercurrent contact with absorption liquid for absorption, and the natural gas is absorbed from the tower of the absorption towerPurified gas and rich liquid rich in carbon dioxide are respectively obtained at the top and the bottom of the tower;
second, high-pressure flash evaporation is carried out to absorb CO2The absorption liquid is subjected to high-pressure flash evaporation to remove the dissolved methane and other hydrocarbons, and the high-pressure flash evaporation pressure is 0.8-1.2 MPa;
thirdly, low-pressure flash evaporation is carried out, so that the absorption liquid of the hydrocarbon which is flashed off enters low-pressure flash evaporation, and is simultaneously stripped by hot flash steam in a low-pressure flash evaporation tank, wherein the pressure of the low-pressure flash evaporation is normal pressure to 0.08 MPa;
fourthly, heating the absorption liquid after low-pressure flash evaporation; heating the absorption liquid subjected to low-pressure flash evaporation to increase the temperature of the absorption liquid by 3-15 ℃;
fifthly, carrying out thermal flash evaporation to the heated absorption liquid, wherein the pressure of the thermal flash evaporation is 0.01-0.09 MPa;
and sixthly, cooling the absorption liquid from the thermal flash evaporation step, and circulating the absorption liquid back to the absorption tower.
2. The method according to claim 1, wherein the temperature of the absorption liquid entering the absorption column is 60 to 75 ℃.
3. The process of claim 1, wherein the absorption liquid is stripped with hot flash vapor simultaneously with the low pressure flash at a pressure of 0.01 to 0.08 MPa.
4. The method as claimed in claim 1, wherein the absorption liquid after low-pressure flash evaporation is heated to 5-10 ℃ and then subjected to thermal flash evaporation again, and the thermal flash evaporation pressure is 0.01-0.08 MPa.
5. The process of claim 1 wherein the flash gas of the thermal flash is used as the stripping gas of the low pressure flash.
6. The method according to claim 1, wherein the absorption liquid is an MDEA solution with an activator added thereto.
7. The method according to claim 6, wherein the absorbent activator is diethanolamine or piperazine and its derivatives or hindered amines.
8. The method according to claim 6, wherein the absorption liquid contains a defoaming agent or a corrosion inhibitor.
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| CN201810739128.8A CN110684575A (en) | 2018-07-06 | 2018-07-06 | Method for removing carbon dioxide in high-pressure natural gas |
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| CN201810739128.8A CN110684575A (en) | 2018-07-06 | 2018-07-06 | Method for removing carbon dioxide in high-pressure natural gas |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN116870663A (en) * | 2023-08-04 | 2023-10-13 | 中国石油天然气集团有限公司 | Amine liquid purification and regeneration system and method |
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2018
- 2018-07-06 CN CN201810739128.8A patent/CN110684575A/en active Pending
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| CN1364096A (en) * | 1999-07-27 | 2002-08-14 | 联合碳化化学及塑料技术公司 | Process for removing contaminants from gas using polyethylene glycols |
| CN105307752A (en) * | 2013-06-14 | 2016-02-03 | Ifp新能源公司 | Process for decarbonation of a hydrocarbon-based gas |
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| 勘察设计注册工程师石油天然气专业管理委员会: "《勘察设计注册石油天然气工程师资格考试专业考试复习指南》", 31 July 2006, 中国石油大学出版社 * |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN116870663A (en) * | 2023-08-04 | 2023-10-13 | 中国石油天然气集团有限公司 | Amine liquid purification and regeneration system and method |
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