CN113959178B - Carbon capture method in hydrogen production process by LNG - Google Patents

Carbon capture method in hydrogen production process by LNG Download PDF

Info

Publication number
CN113959178B
CN113959178B CN202111431459.3A CN202111431459A CN113959178B CN 113959178 B CN113959178 B CN 113959178B CN 202111431459 A CN202111431459 A CN 202111431459A CN 113959178 B CN113959178 B CN 113959178B
Authority
CN
China
Prior art keywords
refrigerant
reaction gas
carbon dioxide
temperature
lng
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Active
Application number
CN202111431459.3A
Other languages
Chinese (zh)
Other versions
CN113959178A (en
Inventor
李欣锐
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Individual
Original Assignee
Individual
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Individual filed Critical Individual
Priority to CN202111431459.3A priority Critical patent/CN113959178B/en
Publication of CN113959178A publication Critical patent/CN113959178A/en
Application granted granted Critical
Publication of CN113959178B publication Critical patent/CN113959178B/en
Active legal-status Critical Current
Anticipated expiration legal-status Critical

Links

Images

Classifications

    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
    • F25J3/00—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification
    • F25J3/02—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by rectification, i.e. by continuous interchange of heat and material between a vapour stream and a liquid stream
    • F25J3/0228—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by rectification, i.e. by continuous interchange of heat and material between a vapour stream and a liquid stream characterised by the separated product stream
    • F25J3/0252—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by rectification, i.e. by continuous interchange of heat and material between a vapour stream and a liquid stream characterised by the separated product stream separation of hydrogen
    • 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
    • B01D53/002—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 by condensation
    • 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
    • B01D53/26—Drying gases or vapours
    • B01D53/265—Drying gases or vapours by refrigeration (condensation)
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
    • C01B3/00—Hydrogen; Gaseous mixtures containing hydrogen; Separation of hydrogen from mixtures containing it; Purification of hydrogen
    • C01B3/02—Production of hydrogen or of gaseous mixtures containing a substantial proportion of hydrogen
    • C01B3/32—Production of hydrogen or of gaseous mixtures containing a substantial proportion of hydrogen by reaction of gaseous or liquid organic compounds with gasifying agents, e.g. water, carbon dioxide, air
    • C01B3/34—Production of hydrogen or of gaseous mixtures containing a substantial proportion of hydrogen by reaction of gaseous or liquid organic compounds with gasifying agents, e.g. water, carbon dioxide, air by reaction of hydrocarbons with gasifying agents
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
    • C01B32/00—Carbon; Compounds thereof
    • C01B32/50—Carbon dioxide
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
    • F25J3/00—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification
    • F25J3/02—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by rectification, i.e. by continuous interchange of heat and material between a vapour stream and a liquid stream
    • F25J3/0228—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by rectification, i.e. by continuous interchange of heat and material between a vapour stream and a liquid stream characterised by the separated product stream
    • F25J3/0266—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by rectification, i.e. by continuous interchange of heat and material between a vapour stream and a liquid stream characterised by the separated product stream separation of carbon dioxide
    • 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
    • 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
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P20/00—Technologies relating to chemical industry
    • Y02P20/10—Process efficiency
    • 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
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P20/00—Technologies relating to chemical industry
    • Y02P20/151—Reduction of greenhouse gas [GHG] emissions, e.g. CO2
    • 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
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P20/00—Technologies relating to chemical industry
    • Y02P20/50—Improvements relating to the production of bulk chemicals
    • 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
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P30/00—Technologies relating to oil refining and petrochemical industry

Abstract

The invention discloses a carbon capture method in a hydrogen production process by LNG, which comprises the following steps: the initial reaction gas discharged by the natural gas hydrogen production device is cooled by an air heat exchanger, and a first reaction gas is output; the first reaction gas enters a heat exchanger for cooling and a second reaction gas is output; the second reaction gas enters a deep dehydrator for cooling, and a third reaction gas is output; the third reaction gas enters a cooler; the carbon dioxide gas in the third reaction gas is converted into liquid in the cooler; the cooler outputs a fourth reaction gas; the fourth reaction gas enters a deep carbon dioxide remover; the carbon dioxide gas in the fourth reaction gas is converted to a liquid in the deep decarbonizer. The invention realizes the capture of carbon dioxide in a liquid form, and can increase the use efficiency of cold energy.

Description

Carbon capture method in hydrogen production process by LNG
Technical Field
The invention relates to a carbon capture method in a hydrogen production process by LNG.
Background
The technology of hydrogen production by natural gas is very mature, is the most economic hydrogen production mode at present, is mainly used in the chemical industry at the beginning, and a large-scale hydrogen production factory is constructed and is conveyed to the chemical factory in a gas state or a liquid state through a pipeline or a vehicle or a ship; with the increasing use of hydrogen fuel cells in the automotive industry, the hydrogenation of automobiles becomes a concern. The storage cost of hydrogen is high, the danger is high, and the hydrogen is not suitable for large-scale storage in cities with dense population; and the natural gas is high in safety and can be obtained in a pipeline or LNG form, so that the miniaturized natural gas hydrogen production equipment is provided, and the demand of distributed hydrogen use is met. For example, a small natural gas hydrogen plant can be installed in a container, the hydrogen production amount reaches 1000 square/hour, and about 0.4 to 0.45 cubic of natural gas can be converted into 1 cubic of hydrogen (the total consumption of natural gas as fuel and raw material) in terms of conversion efficiency.
The existing small-sized hydrogen production equipment using LNG has the following process flow in the aspect of carbon capture: after the conversion of the 'natural gas hydrogen production device', the converted reaction gas (the main components of the reaction gas are hydrogen, methane and carbon dioxide, and also comprise a small amount of carbon monoxide, water vapor and other gases) enters the 'hydrogen freezing and purifying device' for treatment, the working temperature of the 'hydrogen freezing and purifying device' reaches-90 ℃, the carbon dioxide (the temperature of the carbon dioxide converted into solid under 2MPa is about-57 ℃) and the water in the reaction gas are converted into solid, other components with lower freezing points are converted into liquid, and the solid and the liquid are sent to a dry ice production device; and tail gas discharged by the natural gas hydrogen production device also enters the dry ice production device to capture carbon dioxide in the dry ice production device.
In the prior art, water, carbon dioxide and other gases are converted into solid or liquid by adopting a freezing mode at the temperature of-90 ℃, and then transferred into a dry ice production device; and tail gas discharged by the natural gas hydrogen production device also enters the dry ice production device to capture carbon dioxide in the dry ice production device.
The prior art has the following disadvantages:
1. the collection and transportation of carbon dioxide are more complicated, and the collection and transportation of carbon dioxide are not as convenient as liquid carbon dioxide;
2. the low-temperature refrigeration mode is used for capturing carbon dioxide, which is not beneficial to the full utilization of the high-grade cold energy of LNG/vaporized gas.
3. The low-temperature refrigeration at minus 90 ℃ is adopted, the low-temperature working temperature of the secondary refrigerant reaches below minus 95 ℃, the selection of the secondary refrigerant is harsh, and even substances such as propane/butane and the like which are flammable and explosive and need to be stored in a pressure container are selected, so the use and maintenance cost is high, and the danger is high;
4. after the 'natural gas hydrogen production device' is converted, the converted mixed gas and the tail gas discharged by the 'natural gas hydrogen production device' have higher temperature, and are directly cooled by using low-temperature 'secondary refrigerant', so that the heat energy in the gases is wasted, a large amount of cold energy is consumed, and the waste of resources and even the deficiency of the cold energy are caused.
Disclosure of Invention
The invention aims to overcome the defects in the prior art and provide a carbon capture method in a hydrogen production process by using LNG.
The invention solves the technical problems through the following technical scheme:
a method of carbon capture in a hydrogen production process from LNG, comprising the steps of:
firstly, cooling an initial reaction gas discharged by a natural gas hydrogen production device through an air heat exchanger, converting part of water vapor in the initial reaction gas into condensed water, and discharging the condensed water, and outputting a first reaction gas by the air heat exchanger;
step two, the first reaction gas enters a heat exchanger which takes a first refrigerant as a secondary refrigerant to be cooled, and after part of water vapor in the first reaction gas is condensed into condensed water and discharged, the heat exchanger outputs a second reaction gas;
step three, the second reaction gas enters a deep dehydrator which takes a second refrigerant as a secondary refrigerant to be cooled, and after part of water vapor in the second reaction gas forms ice and is discharged, the deep dehydrator outputs a third reaction gas;
step four, the third reaction gas enters a cooler which takes a third refrigerant as a secondary refrigerant; the carbon dioxide gas in the third reaction gas is converted into liquid in the cooler; the carbon dioxide liquid is conveyed to a liquid carbon dioxide storage tank; the cooler outputs a fourth reaction gas;
step five, the fourth reaction gas enters a deep carbon dioxide remover which takes a third refrigerant as a secondary refrigerant; the carbon dioxide gas in the fourth reaction gas is converted to a liquid in the deep decarbonizer and the carbon dioxide liquid is transferred to a liquid carbon dioxide storage tank.
In the preferred scheme, the LNG storage tank is used as a natural gas raw material source for the natural gas hydrogen production device; the LNG storage tank is sequentially connected with an LNG gasification/low-temperature heater and a low-temperature natural gas heater; the third refrigerant flowing out of the device taking the third refrigerant as the secondary refrigerant enters the LNG gasification/low-temperature heater, and the third refrigerant cooled by the LNG gasification/low-temperature heater respectively enters the device taking the third refrigerant as the secondary refrigerant to form flow path circulation of the third refrigerant; the third refrigerant is used as a heating source of the LNG gasification/low-temperature heater, and the LNG gasification/low-temperature heater is used as a cooling part of the third refrigerant; the second refrigerant flowing out of the deep dehydrator enters the low-temperature natural gas heater, and the second refrigerant cooled by the low-temperature natural gas heater is taken as secondary refrigerant and then enters the deep dehydrator to form flow path circulation of the second refrigerant; the second refrigerant is used as a heating source of the low-temperature natural gas heater, and the low-temperature natural gas heater is used as a cooling part of the second refrigerant; the natural gas in the LNG storage tank is heated by the LNG gasification/low-temperature heater and the low-temperature natural gas heater in sequence, the natural gas flowing out of the low-temperature natural gas heater serves as a first refrigerant, and the first refrigerant serves as a secondary refrigerant of the heat exchanger and then flows back to the natural gas hydrogen production device.
In the preferred scheme, the temperature of the third reaction gas output by the deep dehydrator is-10 ℃ to-15 ℃; the temperature of the fourth reaction gas output by the cooler is-50 ℃ to-30 ℃.
In a preferred scheme, the initial reaction gas discharged by the natural gas hydrogen production device is crude hydrogen containing hydrogen, carbon dioxide and other gases, and the pressure of the initial reaction gas, the first reaction gas, the second reaction gas, the third reaction gas and the fourth reaction gas is 0.8 MPa-2.5 MPa.
In a preferred scheme, the initial reaction gas discharged by the natural gas hydrogen production device is waste gas generated by burning fuel used by the natural gas hydrogen production device.
In the preferable scheme, the temperature of a first refrigerant flowing out of the low-temperature natural gas heater is-20 ℃ to-10 ℃; the temperature of a second refrigerant flowing out of the low-temperature natural gas heater is-25 ℃ to-15 ℃; the temperature of the third refrigerant flowing out of the LNG vaporization/low temperature heater is-95 ℃ to-85 ℃.
In the preferred scheme, two water removal parts are arranged in the inner cavity of the deep water remover, the inner cavity of each water removal part is used for a second refrigerant to pass through, and a second reaction gas flow entering the deep water remover passes through the surfaces of the water removal parts; two water removal units are arranged in parallel.
In the preferred scheme, two carbon dioxide removing parts are arranged in the inner cavity of the deep carbon dioxide remover, the inner cavity of each carbon dioxide removing part is used for a third refrigerant to pass through, and a fourth reaction gas entering the deep carbon dioxide remover flows through the surfaces of the carbon dioxide removing parts; the two carbon dioxide removing components are arranged in parallel.
Preferably, the third refrigerant is used as the secondary refrigerant for cooling the liquid carbon dioxide storage tank.
Preferably, the method for capturing carbon in the process of producing hydrogen by using LNG further comprises a sixth step of inputting the liquid carbon dioxide in the liquid carbon dioxide storage tank into a dry ice production device, and converting the liquid carbon dioxide into dry ice by the dry ice production device; the dry ice production device takes a third refrigerant as a secondary refrigerant.
The invention has the beneficial effects that: the invention improves the prior art of the process flow for producing hydrogen by using Liquefied Natural Gas (LNG), reasonably utilizes the cold energy of the LNG in the hydrogen production process, realizes the capture, transportation and storage of carbon dioxide in a liquid form, and is particularly suitable for carbon capture of distributed hydrogen production without pipeline natural gas supply. The invention can reduce the use of high-grade LNG cold energy and increase the use efficiency of the cold energy; the invention can improve the working temperature of the carbon dioxide capture equipment, reduce the unreasonable consumption of high-grade cold energy and increase the use efficiency of the high-grade cold energy; the heat exchange process is reasonably optimized, so that the cold energy in the hydrogen production process of LNG can be reasonably utilized, and safer secondary refrigerants such as methanol and the like can be used. The method is used for carbon capture in the LNG hydrogen production process and related energy reasonable utilization modes, and under the common conditions, the method is more commonly used for small hydrogen production devices.
Drawings
FIG. 1 is a schematic diagram of a preferred embodiment of the present invention.
Fig. 2 is a schematic diagram of a circuit for outputting natural gas from an LNG storage tank according to a preferred embodiment of the present invention.
Fig. 3 is a schematic circuit diagram of a third refrigerant according to a preferred embodiment of the invention.
Fig. 4 is a schematic circuit diagram of a second refrigerant according to a preferred embodiment of the invention.
Detailed Description
The present invention will be more fully described by the following two preferred embodiments in conjunction with the accompanying drawings.
The initial reaction gas discharged by the natural gas hydrogen production device is crude hydrogen containing hydrogen, carbon dioxide and other gases, or is waste gas generated after the natural gas hydrogen production device burns by taking natural gas as fuel.
The process will now be more clearly and completely described with reference to the initial reaction gas being crude hydrogen and off gas, respectively.
Example 1
According to the existing process flow, two-step chemical reaction is carried out in a natural gas hydrogen production device, wherein the two-step chemical reaction is respectively carried out at the temperature of more than 800 DEG CEndothermic reactions (CH) of natural gas and water to produce carbon monoxide and hydrogen occur 4 +H 2 O→CO+2H 2 ) And the exothermic reaction (CO + H) of carbon monoxide and water to produce carbon dioxide and hydrogen, which takes place at a temperature of 300-400 DEG C 2 O→CO 2 +H 2 ). The main components of the reacted gas (i.e., crude hydrogen, i.e., "initial reaction gas" in this example) are hydrogen, carbon dioxide, steam, carbon monoxide and methane, and the pressure of the initial reaction gas is generally 1 to 2.5MPa.
In this example, the flow of capturing carbon dioxide in the initial reaction gas will be described by taking the initial reaction gas temperature of 120 ℃ and the pressure of 2MPa as an example.
A method of carbon capture in a hydrogen production process from LNG, as shown in fig. 1, 2, 3 and 4, comprising the steps of:
firstly, the initial reaction gas 20 discharged from the natural gas hydrogen production device 10 is cooled by the air heat exchanger 30, and after part of the water vapor in the initial reaction gas is converted into condensed water and discharged, the air heat exchanger 30 outputs a first reaction gas 21.
The initial reaction gas is cooled by the air heat exchanger, and the temperature is reduced to about 70 ℃ after the heat is discharged to the atmosphere, namely the temperature of the first reaction gas is about 70 ℃.
And step two, the first reaction gas 21 enters a heat exchanger 40 which takes a first refrigerant 31 as a secondary refrigerant to cool, and the temperature of the first refrigerant is-20 ℃ to-10 ℃. After part of the water vapor in the first reaction gas is condensed into condensed water and discharged, the heat exchanger outputs a second reaction gas 22. The temperature of the second reaction gas is about 40 ℃.
And step three, the second reaction gas 22 enters a deep dehydrator 50 which takes a second refrigerant 32 as a secondary refrigerant to cool, wherein the temperature of the second refrigerant is-25 ℃ to-15 ℃. After ice is formed from part of the water vapor in the second reaction gas and discharged, the deep dehydrator outputs a third reaction gas 23. The temperature of the third reaction gas output by the deep dehydrator is-10 ℃ to-15 ℃.
The inner cavity of the deep dehydrator 50 is provided with two dehydrating components 51, the inner cavity of the dehydrating components is used for a second refrigerant to pass through, and a second reaction gas entering the deep dehydrator flows through the surface of the dehydrating components; two water removal components are arranged in parallel.
The principle of the deep dehydrator is as follows: the surface temperature of the dewatering component is reduced through the refrigerant, when the second reaction gas flows through the surface of the dewatering component, the water vapor in the second reaction gas is frozen and is retained in the inner cavity of the deep water remover, and therefore the water vapor in the second reaction gas is removed.
Since the water vapor in the second reaction gas forms ice on the surface of the water removing part, the passing resistance of the second reaction gas is increased along with the excessive ice, and for this reason, two water removing parts are arranged in parallel in the deep water remover. When the ice on the surface of one water removing part is excessive, switching to another water removing part for water removal; meanwhile, the temperature of the first water removal part is raised to about 10 ℃, so that ice is converted into water and discharged through a pipeline.
After the second reaction gas passes through the deep dehydrator, almost all water vapor in the second reaction gas is removed. The deep dehydrator outputs a third reaction gas. The main components of the third reaction gas are hydrogen, carbon dioxide, carbon monoxide and methane, and other gas components are small or trace, and the temperature of the third reaction gas is about-10 ℃.
Step four, the third reaction gas 23 enters a cooler 60 which takes a third refrigerant 33 as a secondary refrigerant; the temperature of the third refrigerant is-95 ℃ to-85 ℃. The carbon dioxide gas in the third reaction gas is converted into liquid in the cooler; the carbon dioxide liquid is delivered to a liquid carbon dioxide storage tank 70 which takes a third refrigerant as a secondary refrigerant; the cooler outputs a fourth reactant gas 24. The temperature of the fourth reaction gas output by the cooler is-50 ℃ to-30 ℃.
The cooler removes most of the carbon dioxide from the third reaction gas and leaves a small amount of carbon dioxide in the fourth reaction gas.
Step five, the fourth reaction gas 24 enters a deep carbon dioxide removal device 80 which takes a third refrigerant 33 as a secondary refrigerant; the temperature of the third refrigerant is-95 ℃ to-85 ℃. The carbon dioxide gas in the fourth reaction gas is converted to a liquid in the deep carbon dioxide remover and the carbon dioxide liquid is transferred to the liquid carbon dioxide storage tank 70.
The structure of the deep carbon dioxide remover is similar to that of the deep water remover.
The inner cavity of the deep carbon dioxide remover 80 is provided with two carbon dioxide removing components 81, the inner cavity of the carbon dioxide removing components is used for a third refrigerant to pass through, and a fourth reaction gas entering the deep carbon dioxide remover flows through the surfaces of the carbon dioxide removing components; the two carbon dioxide removing components are arranged in parallel.
The principle of the deep carbon dioxide remover is as follows: when the surface temperature of the carbon dioxide removing part is reduced by the refrigerant and the fourth reaction gas flows through the surface of the carbon dioxide removing part, the carbon dioxide in the fourth reaction gas is cooled and liquefied to even form dry ice, so that the carbon dioxide in the fourth reaction gas is removed.
Two carbon dioxide removing parts are arranged in the deep carbon dioxide remover in parallel. When the dry ice on the surface of one carbon dioxide removing component is excessive, switching to the other carbon dioxide removing component to work; and simultaneously, heating the first carbon dioxide removing part to convert the dry ice into liquid carbon dioxide and conveying the liquid carbon dioxide to a carbon dioxide storage tank.
After the above five steps, the deep decarbonizer discharges a fifth reaction gas 25, the main components of which are hydrogen, methane and carbon monoxide. By the above steps, carbon dioxide in the initial reaction gas can be successfully removed.
In the above step, methanol may be used as the third refrigerant. The solidifying point of the methanol is-98 ℃, the methanol is liquid at normal temperature, the storage requirement is lower, and the maintenance cost can be effectively reduced.
The second refrigerant can be methanol or glycol solution. Wherein, the methanol management is convenient, and the glycol solution is safer.
The LNG storage tank is used as a natural gas raw material source for the natural gas hydrogen production device; the LNG storage tank is sequentially connected with an LNG gasification/low-temperature heater and a low-temperature natural gas heater.
In order to improve the utilization rate of cold energy, in the above steps, the second refrigerant and the third refrigerant are cooled by a low-temperature natural gas heater and an LNG vaporization/low-temperature heater, and meanwhile, the first refrigerant may also be natural gas output by an LNG storage tank.
Specifically (as shown in fig. 2, 3 and 4):
the third refrigerant 33 flowing out of the device using the third refrigerant as the secondary refrigerant enters the LNG vaporization/low temperature heater 12, and the third refrigerant cooled by the LNG vaporization/low temperature heater respectively enters the device using the third refrigerant as the secondary refrigerant to form a flow path circulation of the third refrigerant; the third refrigerant is used as a heating source of the LNG vaporization/low-temperature heater, and the LNG vaporization/low-temperature heater is used as a cooling part of the third refrigerant.
The second refrigerant 32 flowing out of the deep dehydrator enters the low-temperature natural gas heater 23, and the second refrigerant cooled by the low-temperature natural gas heater is taken as secondary refrigerant and then enters the deep dehydrator to form flow path circulation of the second refrigerant; the second refrigerant is used as a heating source of the low-temperature natural gas heater, and the low-temperature natural gas heater is used as a cooling part of the second refrigerant.
The natural gas in the LNG storage tank is heated by the LNG gasification/low-temperature heater and the low-temperature natural gas heater in sequence, the natural gas flowing out of the low-temperature natural gas heater 13 serves as a first refrigerant 31, and the first refrigerant serves as a secondary refrigerant of the heat exchanger and then flows back to the natural gas hydrogen production device.
And storing the liquid carbon dioxide obtained by the steps in a liquid carbon dioxide storage tank. And taking the third refrigerant as a secondary refrigerant for cooling the liquid carbon dioxide storage tank.
The cooling capacity of LNG becomes cooling energy. The cold energy may be classified according to its different temperature stages. The cold energy with lower temperature is called high-grade cold energy because the grade of the cold energy is high due to the strong cooling capacity. The cooling energy having a higher temperature than the high-grade cooling energy is called low-grade cooling energy because the cooling energy has a slightly lower grade due to its slightly lower cooling capacity.
The invention can use the cold energy in grades, and avoids the waste caused by directly cooling the high-temperature gas by the high-grade cold energy. In the present invention, as shown in fig. 2, fig. 3 and fig. 4, the higher-grade cooling energy is carried and transmitted by the third cooling medium, the lower-grade cooling energy is carried and transmitted by the second cooling medium, and the natural gas (natural gas 31 in fig. 2) after the initial temperature rise can carry the lowest-grade cooling energy by itself as the first cooling medium.
According to the invention, through the graded utilization of the LNG cold energy, the second refrigerant and the third refrigerant can be cooled without using additional cooling energy for the second refrigerant and the third refrigerant. Therefore, the waste of the cold energy of the LNG is avoided, the cold energy of the LNG is fully utilized, the cost for cooling the refrigerant is reduced, and the LNG refrigeration system has high economic value.
In the present invention, the principle of carbon capture application is a simple physical principle: carbon dioxide varies in its physical state at different temperatures. Specifically, the method comprises the following steps: the carbon dioxide is cooled, so that the carbon dioxide is changed into a liquid state or a solid state from a gaseous state.
From the physical properties of carbon dioxide described in textbooks and technical dictionaries: the carbon dioxide form can be controlled by using the heat conduction and the matter state change, namely the carbon dioxide liquefaction is realized by controlling the temperature of the heat conduction by using the pressure parameter of the hydrogen production process. The above forms the carbon capture technical idea of the present invention.
Based on the technical ideas, the invention skillfully utilizes the method of graded temperature reduction by combining the technical defects of carbon capture in the hydrogen production process, thereby realizing more effective carbon capture. Meanwhile, the LNG cold energy is utilized in a grading manner, waste caused by inefficient use of high-grade cold energy is avoided, and the idea of LNG cold energy use is formed.
The method has the following advantages:
1. in a miniaturized hydrogen production device using LNG as a raw material, carbon dioxide is recovered in a liquid state mode, and a pump and a pipeline are convenient to use for collection and conveying.
2. The method can improve the working temperature of the carbon dioxide capture equipment and increase the utilization efficiency of cold energy.
3. And a safer secondary refrigerant is used, so that the whole process is safer.
4. The heat exchange process is reasonably optimized, so that the cold energy (especially high-grade cold energy) in the hydrogen production process of the LNG can be reasonably utilized, the equipment is simplified, and the investment cost is reduced.
In addition, if the liquid carbon dioxide needs to be converted into dry ice, the method further comprises a sixth step of inputting the liquid carbon dioxide in the liquid carbon dioxide storage tank 70 into a dry ice production device 90, and the dry ice production device converts the liquid carbon dioxide into dry ice; the dry ice production device takes a third refrigerant as a secondary refrigerant.
The carbon dioxide is converted into solid from liquid in a controlled state, the shape, volume and the like of the dry ice can be controlled, and the dry ice meeting the final use requirement can be directly produced.
Example 2
As described in example 1, a natural gas hydrogen plant produces hydrogen and requires two chemical reactions. Wherein the first step chemical reaction is an endothermic reaction (CH) of natural gas and water to produce carbon monoxide and hydrogen occurring above 800 deg.C 4 +H 2 O→CO+2H 2 ). To achieve the 800 ℃ requirement, certain fuels need to be burned to achieve high temperatures above 800 ℃ and to provide the heat required for the reaction. Since natural gas and/or PSA purge gas are generally used as fuel, the fuel contains carbon-containing components such as methane and carbon monoxide. Thus, the main components of the exhaust gas (exhaust gas) after combustion of the fuel are nitrogen, oxygen, carbon dioxide and water vapor, and the temperature is 150 ℃ or higher.
In this embodiment, a flow of capturing carbon dioxide in an initial reaction gas is described by taking an exhaust gas generated by burning natural gas as a fuel in a natural gas hydrogen production apparatus as the initial reaction gas, the initial reaction gas having a temperature of 150 ℃ and a pressure of 0.2MPa as examples.
A method of carbon capture in a hydrogen production process from LNG, comprising the steps of:
firstly, the initial reaction gas discharged by the natural gas hydrogen production device is cooled by an air heat exchanger, partial water vapor in the initial reaction gas is converted into condensed water and discharged, and the air heat exchanger outputs the first reaction gas.
The initial reaction gas is cooled by the air heat exchanger, and the temperature is reduced to about 70 ℃ after the heat is discharged to the atmosphere, namely the temperature of the first reaction gas is about 70 ℃.
And step two, the first reaction gas enters a heat exchanger which takes a first refrigerant as a secondary refrigerant to cool, and the temperature of the first refrigerant is-20 ℃ to-10 ℃. And after part of water vapor in the first reaction gas is condensed into condensed water and discharged, the heat exchanger outputs a second reaction gas. The temperature of the second reaction gas is about 40 ℃.
And step three, cooling the second reaction gas in a deep dehydrator taking a second refrigerant as a secondary refrigerant, wherein the temperature of the second refrigerant is-25 ℃ to-15 ℃. And after part of water vapor in the second reaction gas forms ice and is discharged, the deep dehydrator outputs a third reaction gas. The temperature of the third reaction gas output by the deep dehydrator is-10 ℃ to-15 ℃.
Step four, the third reaction gas is pressurized to 1-2 MPa and then enters a cooler taking a third refrigerant as a secondary refrigerant; the temperature of the third refrigerant is-95 ℃ to-85 ℃. The carbon dioxide gas in the third reaction gas is converted into liquid in the cooler; the carbon dioxide liquid is conveyed to a liquid carbon dioxide storage tank which takes a third refrigerant as a secondary refrigerant; the cooler outputs a fourth reaction gas. The temperature of the fourth reaction gas output by the cooler is-50 ℃ to-30 ℃.
Step five, the fourth reaction gas enters a deep carbon dioxide remover which takes a third refrigerant as a secondary refrigerant; the temperature of the third refrigerant is-95 ℃ to-85 ℃. The carbon dioxide gas in the fourth reaction gas is converted to a liquid in the deep decarbonizer and the carbon dioxide liquid is transferred to a liquid carbon dioxide storage tank.
After the five steps, the main components of the reaction gas discharged by the deep carbon dioxide remover are nitrogen and oxygen. By the above steps, carbon dioxide in the initial reaction gas can be successfully removed.
Otherwise, the same as in example 1 was applied. Compared with example 1, example 2 is only different from the initial reaction gas, so example 2 does not list the attached drawing, and can refer to the attached drawing of example 1.
In addition to the above two embodiments, the method of the present invention may be implemented in other ways, which are not listed here.
The invention improves the prior art of the process flow for producing hydrogen by using Liquefied Natural Gas (LNG), reasonably utilizes the cold energy of the LNG in the hydrogen production process, realizes the capture, transportation and storage of carbon dioxide in a liquid form, and is particularly suitable for the carbon capture of distributed hydrogen production without pipeline natural gas supply.
The invention can reduce the use of high-grade LNG cold energy and increase the use efficiency of the cold energy; the invention can improve the working temperature of the carbon dioxide capture equipment, reduce the unreasonable consumption of high-grade cold energy and increase the use efficiency of the high-grade cold energy; the heat exchange process is reasonably optimized, so that the cold energy in the hydrogen production process of LNG can be reasonably utilized, and safer secondary refrigerants such as methanol and the like can be used.
The method is used for carbon capture in the hydrogen production process of LNG and related energy reasonable utilization modes, and under the common condition, a small hydrogen production device is more commonly used.
While specific embodiments of the invention have been described above, it will be appreciated by those skilled in the art that this is by way of example only, and that the scope of the invention is defined by the appended claims. Various changes or modifications to these embodiments may be made by those skilled in the art without departing from the principle and spirit of this invention, and these changes and modifications are within the scope of this invention.

Claims (9)

1. A carbon capture method in a hydrogen production process by LNG is characterized by comprising the following steps:
firstly, cooling an initial reaction gas discharged by a natural gas hydrogen production device through an air heat exchanger, converting part of water vapor in the initial reaction gas into condensed water, and discharging the condensed water, and outputting a first reaction gas by the air heat exchanger;
step two, the first reaction gas enters a heat exchanger which takes a first refrigerant as a secondary refrigerant to be cooled, and after part of water vapor in the first reaction gas is condensed into condensed water and discharged, the heat exchanger outputs a second reaction gas;
step three, the second reaction gas enters a deep dehydrator which takes a second refrigerant as a secondary refrigerant to be cooled, and after part of water vapor in the second reaction gas forms ice and is discharged, the deep dehydrator outputs a third reaction gas;
step four, the third reaction gas enters a cooler taking a third refrigerant as a secondary refrigerant; the carbon dioxide gas in the third reaction gas is converted into liquid in the cooler; the carbon dioxide liquid is conveyed to a liquid carbon dioxide storage tank; the cooler outputs a fourth reaction gas;
step five, the fourth reaction gas enters a deep carbon dioxide removal device taking a third refrigerant as a secondary refrigerant; the carbon dioxide gas in the fourth reaction gas is converted into liquid in the deep carbon dioxide remover, and the carbon dioxide liquid is conveyed to a liquid carbon dioxide storage tank;
the LNG storage tank is used as a natural gas raw material source for the natural gas hydrogen production device; the LNG storage tank is sequentially connected with an LNG gasification/low-temperature heater and a low-temperature natural gas heater; the third refrigerant flowing out of the device taking the third refrigerant as the secondary refrigerant enters the LNG gasification/low-temperature heater, and the third refrigerant cooled by the LNG gasification/low-temperature heater respectively enters the device taking the third refrigerant as the secondary refrigerant to form flow path circulation of the third refrigerant; the third refrigerant is used as a heating source of the LNG gasification/low-temperature heater, and the LNG gasification/low-temperature heater is used as a cooling part of the third refrigerant; the second refrigerant flowing out of the deep dehydrator enters the low-temperature natural gas heater, and the second refrigerant cooled by the low-temperature natural gas heater is taken as secondary refrigerant and then enters the deep dehydrator to form flow path circulation of the second refrigerant; the second refrigerant is used as a heating source of the low-temperature natural gas heater, and the low-temperature natural gas heater is used as a cooling part of the second refrigerant; the natural gas in the LNG storage tank is heated by the LNG gasification/low-temperature heater and the low-temperature natural gas heater in sequence, the natural gas flowing out of the low-temperature natural gas heater serves as a first refrigerant, and the first refrigerant serves as a secondary refrigerant of the heat exchanger and then flows back to the natural gas hydrogen production device.
2. The carbon capture method in the hydrogen production process by LNG as claimed in claim 1, wherein the temperature of the third reaction gas output by the deep dehydrator is-10 ℃ to-15 ℃; the temperature of the fourth reaction gas output by the cooler is minus 50 ℃ to minus 30 ℃.
3. The method for capturing carbon in a hydrogen production process using LNG according to claim 1, wherein the initial reaction gas discharged from the natural gas hydrogen production apparatus is crude hydrogen gas containing hydrogen gas, carbon dioxide, and other gases, and the pressure of the initial reaction gas, the first reaction gas, the second reaction gas, the third reaction gas, and the fourth reaction gas is 0.8MPa to 2.5MPa.
4. The method for capturing carbon in the process of producing hydrogen from LNG as claimed in claim 1, wherein the initial reaction gas discharged from the natural gas hydrogen production apparatus is an exhaust gas obtained by burning a fuel used in the natural gas hydrogen production apparatus.
5. The method for capturing carbon in the process of producing hydrogen from LNG according to claim 1, wherein the temperature of the first refrigerant flowing out of the low-temperature natural gas heater is-20 ℃ to-10 ℃; the temperature of a second refrigerant flowing out of the low-temperature natural gas heater is minus 25 ℃ to minus 15 ℃; the temperature of the third refrigerant flowing out of the LNG gasification/low temperature heater is-95 ℃ to-85 ℃.
6. The method for capturing carbon in a process of producing hydrogen from LNG as claimed in claim 1, wherein the deep dehydrator has two dehydration parts in its inner cavity, the inner cavity of the dehydration part is used for the second refrigerant to pass through, and the second reaction gas entering the deep dehydrator flows through the surface of the dehydration part; two water removal units are arranged in parallel.
7. The carbon capture method in the hydrogen production process with LNG as recited in claim 1, wherein the inner cavity of the deep carbon dioxide remover is provided with two carbon dioxide removing parts, the inner cavity of the carbon dioxide removing part is used for the third refrigerant to pass through, and the fourth reactant gas entering the deep carbon dioxide remover flows on the surface of the carbon dioxide removing part; the two carbon dioxide removing components are arranged in parallel.
8. The method of claim 1, wherein the third refrigerant is used as a coolant to cool the liquid carbon dioxide storage tank.
9. The method for capturing carbon in a hydrogen production process using LNG according to claim 1, wherein the method for capturing carbon in a hydrogen production process using LNG further comprises a sixth step of introducing liquid carbon dioxide in a liquid carbon dioxide storage tank into a dry ice production device, the dry ice production device converting the liquid carbon dioxide into dry ice; the dry ice production device takes a third refrigerant as a secondary refrigerant.
CN202111431459.3A 2021-11-29 2021-11-29 Carbon capture method in hydrogen production process by LNG Active CN113959178B (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
CN202111431459.3A CN113959178B (en) 2021-11-29 2021-11-29 Carbon capture method in hydrogen production process by LNG

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
CN202111431459.3A CN113959178B (en) 2021-11-29 2021-11-29 Carbon capture method in hydrogen production process by LNG

Publications (2)

Publication Number Publication Date
CN113959178A CN113959178A (en) 2022-01-21
CN113959178B true CN113959178B (en) 2023-01-20

Family

ID=79472446

Family Applications (1)

Application Number Title Priority Date Filing Date
CN202111431459.3A Active CN113959178B (en) 2021-11-29 2021-11-29 Carbon capture method in hydrogen production process by LNG

Country Status (1)

Country Link
CN (1) CN113959178B (en)

Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS5532784A (en) * 1978-08-31 1980-03-07 Seitetsu Kagaku Co Ltd Production of liquefied carbon dioxide
US4822393A (en) * 1988-06-30 1989-04-18 Kryos Energy Inc. Natural gas pretreatment prior to liquefaction
CN101913604A (en) * 2010-07-20 2010-12-15 浙江大学 Device and method for manufacturing dry ice by using liquefied natural gas cold energy
CN101922352A (en) * 2009-06-17 2010-12-22 中国科学院工程热物理研究所 Thermal circulation system cooled by liquefied natural gas and flow
CN105115245A (en) * 2015-08-11 2015-12-02 中海油能源发展股份有限公司北京冷能利用研究所 System device for trapping liquefied carbon dioxide by using cold energy of liquefied natural gas and method of device
CN106731600A (en) * 2016-12-20 2017-05-31 新疆敦华石油技术股份有限公司 A kind of collecting carbonic anhydride liquefying plant
CN110980646A (en) * 2019-12-30 2020-04-10 华南理工大学 System and method for preparing hydrogen from liquefied natural gas with CCS

Patent Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS5532784A (en) * 1978-08-31 1980-03-07 Seitetsu Kagaku Co Ltd Production of liquefied carbon dioxide
US4822393A (en) * 1988-06-30 1989-04-18 Kryos Energy Inc. Natural gas pretreatment prior to liquefaction
CN101922352A (en) * 2009-06-17 2010-12-22 中国科学院工程热物理研究所 Thermal circulation system cooled by liquefied natural gas and flow
CN101913604A (en) * 2010-07-20 2010-12-15 浙江大学 Device and method for manufacturing dry ice by using liquefied natural gas cold energy
CN105115245A (en) * 2015-08-11 2015-12-02 中海油能源发展股份有限公司北京冷能利用研究所 System device for trapping liquefied carbon dioxide by using cold energy of liquefied natural gas and method of device
CN106731600A (en) * 2016-12-20 2017-05-31 新疆敦华石油技术股份有限公司 A kind of collecting carbonic anhydride liquefying plant
CN110980646A (en) * 2019-12-30 2020-04-10 华南理工大学 System and method for preparing hydrogen from liquefied natural gas with CCS

Also Published As

Publication number Publication date
CN113959178A (en) 2022-01-21

Similar Documents

Publication Publication Date Title
CN100549389C (en) The power generation system of carbon dioxide separation and method
Baccioli et al. Small scale bio-LNG plant: Comparison of different biogas upgrading techniques
CN100365246C (en) Power system with enhanced thermodynamic efficiency and pollution control
AU2013264211B2 (en) Liquid hydrogen production device
CN109386316B (en) LNG cold energy and BOG combustion energy combined utilization system and method
CN101274746A (en) Reforming system for combined cycle plant with partial CO2 capture
CN108795508B (en) Method for separating coke oven gas by utilizing expansion refrigeration of nitrogen and helium
US20120198884A1 (en) Method for Production of Carbon Dioxide and Apparatus Therefor
JP6951613B1 (en) Carbon dioxide recovery hydrogen production system utilizing LNG
CN101922352A (en) Thermal circulation system cooled by liquefied natural gas and flow
CN101566104B (en) Method and device for zero emission of carbon dioxide by utilizing liquid hydrogen condensation
US11614280B2 (en) Reforming system connected with a raw material gas vaporization system
CN102102586A (en) Peak load power generation device
CN104266454A (en) Liquefied natural gas production system with gas-supercritical carbon dioxide united power
CN101747131B (en) Method for extracting hydrogen and methane from coke oven gas by utilizing membrane separation and low-temperature rectification
CN201104074Y (en) Skid mounted biogas purifying and liquefying device
CN103803492B (en) The method of low temperature pyrogenation coal gas hydrogen manufacturing cogeneration LNG
WO2019030688A1 (en) Process for the treatment of a gas mixture comprising methane, hydrogen, carbon oxide and carbon dioxide
US20070163256A1 (en) Apparatus and methods for gas production during pressure letdown in pipelines
JP2002243360A (en) Method and facility for producing liquid hydrogen
CA2552366A1 (en) Apparatus and methods for gas production during pressure letdown in pipelines
CN100402918C (en) Liquified natural gas pressure raising gasification process conprehensive energy using system in gas station
CN113959178B (en) Carbon capture method in hydrogen production process by LNG
CN101126041A (en) Cascade connection method for preparing liquefied natural gas
KR20220053060A (en) Hydrogen-floating production and treatment system

Legal Events

Date Code Title Description
PB01 Publication
PB01 Publication
SE01 Entry into force of request for substantive examination
SE01 Entry into force of request for substantive examination
GR01 Patent grant
GR01 Patent grant