CN114149837B - Process for preparing liquefied natural gas and co-producing liquid ammonia or hydrogen by coke oven gas with conversion decarburization - Google Patents

Process for preparing liquefied natural gas and co-producing liquid ammonia or hydrogen by coke oven gas with conversion decarburization Download PDF

Info

Publication number
CN114149837B
CN114149837B CN202111272968.6A CN202111272968A CN114149837B CN 114149837 B CN114149837 B CN 114149837B CN 202111272968 A CN202111272968 A CN 202111272968A CN 114149837 B CN114149837 B CN 114149837B
Authority
CN
China
Prior art keywords
gas
oven gas
coke oven
hydrogen
coke
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
CN202111272968.6A
Other languages
Chinese (zh)
Other versions
CN114149837A (en
Inventor
汪涛
蹇守华
胡瑜飞
吴路平
刘琴
袁家均
杨柱荣
龙雨谦
葛得翠
杨运超
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.)
Southwest Research and Desigin Institute of Chemical Industry
Original Assignee
Southwest Research and Desigin Institute of Chemical Industry
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 Southwest Research and Desigin Institute of Chemical Industry filed Critical Southwest Research and Desigin Institute of Chemical Industry
Priority to CN202111272968.6A priority Critical patent/CN114149837B/en
Publication of CN114149837A publication Critical patent/CN114149837A/en
Application granted granted Critical
Publication of CN114149837B publication Critical patent/CN114149837B/en
Active legal-status Critical Current
Anticipated expiration legal-status Critical

Links

Images

Classifications

    • 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
    • C10L3/08—Production of synthetic natural gas
    • 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
    • C01B3/50—Separation of hydrogen or hydrogen containing gases from gaseous mixtures, e.g. purification
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01C—AMMONIA; CYANOGEN; COMPOUNDS THEREOF
    • C01C1/00—Ammonia; Compounds thereof
    • C01C1/02—Preparation, purification or separation of ammonia
    • C01C1/04—Preparation of ammonia by synthesis in the gas phase
    • 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
    • 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
    • Y02P20/129—Energy recovery, e.g. by cogeneration, H2recovery or pressure recovery turbines

Landscapes

  • Chemical & Material Sciences (AREA)
  • Organic Chemistry (AREA)
  • Oil, Petroleum & Natural Gas (AREA)
  • Engineering & Computer Science (AREA)
  • Inorganic Chemistry (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • General Chemical & Material Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • Analytical Chemistry (AREA)
  • Industrial Gases (AREA)

Abstract

The invention discloses a process for preparing liquefied natural gas and co-producing liquid ammonia or hydrogen by using transformed decarbonized coke oven gas, which comprises the following steps: the coke-oven gas is subjected to process units such as compression purification, hydrodesulfurization, conversion, decarburization, methanation, cryogenic separation and the like, liquid obtained after cryogenic separation is an LNG product, and the gas can be used as a hydrogen-nitrogen raw material of a downstream ammonia synthesis device to produce a liquid ammonia product or as a raw material of a PSA hydrogen extraction device to produce pure hydrogen after reheating. The process has the advantages of high utilization rate of effective components in the coke oven gas, good process reliability, low comprehensive energy consumption, large operation flexibility and the like.

Description

Process for preparing liquefied natural gas and co-producing liquid ammonia or hydrogen by coke oven gas with conversion decarburization
Technical Field
The invention belongs to the field of efficient clean utilization of coke oven gas, and particularly relates to a process for preparing liquefied natural gas and co-producing liquid ammonia or hydrogen by using coke oven gas with shift decarburization.
Background
1. Technology for preparing liquefied natural gas and co-producing liquid ammonia from coke oven gas
The method adopts the prior technology of preparing liquefied natural gas and liquid ammonia by coke oven gas, and mainly produces methane by the synthetic reaction of all non-methane carbon-containing compounds in the coke oven gas and hydrogen. The main part of the technologyThe purpose is to produce liquefied natural gas, liquid ammonia is only a byproduct, and the yield is small. Because the coke oven gas contains a large amount of CO and CO 2 The total amount of the gas accounts for-12% of the raw material coke oven gas, if the methane is completely synthesized, a large amount of hydrogen is consumed, and the consumed hydrogen accounts for about-80% of the total amount of the hydrogen in the coke oven gas, so that the yield of liquid ammonia products is greatly reduced.
2. Technology for preparing liquefied natural gas from coke oven gas
By adopting the prior technology for preparing liquefied natural gas by coke oven gas, hydrogen and nitrogen which account for about 15 percent of the total amount of the coke oven gas are abundant, and if the hydrogen and the nitrogen are not well utilized, the part of gas can only be returned to the coke oven to be used as fuel. From the investment perspective, gas accounting for about 15 percent of the total gas amount of the coke oven gas is useless in the whole process, and the investment of the device is increased; from the energy consumption perspective, about 15% of the total gas quantity of the coke oven gas is compressed from the normal pressure to 2.4MPaG, and finally, the gas is reduced to the normal pressure to be used as fuel, and the compression work is wasted. Therefore, if the coke oven gas only produces liquefied natural gas without considering the comprehensive utilization of the tail gas, the method is not economical, and particularly, the method is not reasonable for a large-scale device for preparing the liquefied natural gas by the coke oven gas.
The coke oven gas contains more sulfides with complex forms, and if the hydrolysis mode is adopted for desulfurization, the total sulfur is difficult to remove the precision required by the downstream methanation process, so that the performance and the service life of the methanation catalyst are influenced. Therefore, the liquefied natural gas prepared by methanation of the coke-oven gas basically adopts a fine desulfurization process after hydroconversion.
3. Technology for preparing LNG and coproducing liquid ammonia by taking coal gas and semi-coke tail gas as raw materials or taking coal gas and coke oven gas as mixed raw materials
In the prior art, the liquefied natural gas is produced by adopting coke oven gas as a raw material and adopting coal gas and semi-coke tail gas as the raw material. Although the general composition of these gases is almost the same, the main components, such as the content of hydrogen and the content of CO, are greatly different, and the forms and the contents of impurities in the gases are also greatly different, so the adopted process method is different and is not strong in comparison with the process of the application.
Disclosure of Invention
The invention aims to provide a process for preparing liquefied natural gas and co-producing liquid ammonia or hydrogen by using coke oven gas with conversion decarburization. In the process, coke oven gas is subjected to process units such as compression purification, hydrodesulfurization, conversion, decarburization, methanation, cryogenic separation and the like, liquid obtained after cryogenic separation is an LNG product, and the gas can be used as a hydrogen and nitrogen raw material of a downstream ammonia synthesis device to produce a liquid ammonia product or used as a raw material of a PSA hydrogen extraction device to produce pure hydrogen after reheating. The process has the advantages of high utilization rate of effective components in the coke oven gas, good process reliability, low comprehensive energy consumption, large operation flexibility and the like.
In order to realize the aim, the invention adopts the following specific technical scheme:
a process for preparing liquefied natural gas and co-producing liquid ammonia or hydrogen by using coke oven gas with conversion decarburization comprises the following steps:
1) Purifying: pretreating the coke-oven gas to obtain primarily purified coke-oven gas;
2) Hydrodesulfurization: carrying out hydrodesulfurization treatment on the primarily purified coke oven gas to remove sulfides in the coke oven gas;
3) And (3) transformation: setting a conversion and waste heat recovery unit to adjust H in the coke oven gas 2 、CO、CO 2 Obtaining the transformed gas according to the proportion;
4) Decarbonization: most of carbon dioxide in the shift gas is removed, and the obtained decarbonized gas is sent to a methanation unit;
5) Methanation: carrying out methanation on the decarbonized gas to obtain a methane-rich gas;
6) Cryogenic separation: and (3) performing a refrigeration separation process on the methane-rich gas by using a mixed refrigerant to obtain an LNG product.
The method comprises the following specific steps:
1) Compression purification
The coke oven gas from coking is pretreated, macromolecular impurities in the coke oven gas are primarily removed by adopting a gas-liquid separation or adsorption mode, and the coke oven gas enters a gas holder for buffering and storage, then enters a compressor for compression and then is sent to a purification process unit. The purification process unit mainly removes impurities such as tar, naphthalene, ammonia, hydrogen cyanide and the like in the coke oven gas to the process requirement indexes in the modes of washing, gas-liquid separation, adsorption and the like. And feeding the purified coke-oven gas into a hydrodesulfurization unit.
As a better embodiment in the application, the coke oven gas is compressed from normal pressure to 1.0-4.5 MPaG by a compressor.
2) Hydrodesulfurization of hydrocarbons
Preheating purified coke-oven gas, sequentially entering a pre-hydrogenation reactor and a primary hydrogenation reactor, removing oxygen in the coke-oven gas, simultaneously converting 90% of organic sulfur into inorganic sulfur, and then entering a primary medium-temperature zinc oxide tank to remove hydrogen sulfide in the coke-oven gas. The coke oven gas from the first-stage medium-temperature zinc oxide tank enters a second-stage hydrogenation reactor to further convert organic sulfur into inorganic sulfur, and then the inorganic sulfur passes through a second-stage medium-temperature zinc oxide tank. The desulfurized gas is sent to a shift unit.
As a preferred embodiment in this application, the sulfur content of the coke oven gas is removed to below 0.1ppmv after the hydrodesulfurization step.
3) Transformation of
The desulfurized gas enters a shift reactor after waste heat recovery and proper steam addition, and the shifted gas is sent to a decarburization unit after byproduct steam and heat recovery.
In a preferred embodiment of the present invention, the carbon monoxide dry basis content of the shifted gas is from 0.2V% to 1.5V%.
4) Decarburization of carbon
The shift gas is decarbonized with MDEA solution.
In a preferred embodiment of the present invention, the dry content of carbon dioxide in the decarbonated gas is 0.1 to 1.5V%.
5) Methanation
The decarbonized gas enters a methanation reactor after being preheated, the methane-rich gas at the outlet of the methanation reactor enters a second-stage methanation reactor after byproduct steam and waste heat are recovered, and CO + CO at the outlet of the second-stage methanation reactor 2 Less than or equal to 20ppm. After waste heat recovery, the waste heat is cooled to 40 ℃ by using circulating water to obtain methane-rich gas, and the main components of the methane-rich gas are hydrogen, methane and nitrogen.
In a preferred embodiment of the present invention, the methane-rich gas comprises hydrogen, methane and nitrogen as main components, wherein the hydrogen is 30-80V%, the methane is 20-60V%, and the nitrogen is 3-8V%.
6) Cryogenic separation
The methane-rich gas is subjected to cryogenic pretreatment, and enters a cold box after water, micro dust and other trace harmful impurities are removed. The cold energy of the cold box is provided by mixed refrigerant and a compressor, an LNG product is obtained after cryogenic separation, and the byproduct cryogenic tail gas enters a downstream production device after reheating.
Compared with the prior art, the invention has the following beneficial effects:
compared with other similar process flows for preparing liquefied natural gas and coproducing liquid ammonia from coke oven gas, the process mainly has the following main differences that the original effective gas components in the coke oven gas are reserved and utilized to a greater extent: hydrogen gas.
1) The process is provided with a conversion process unit, and converts the liquefied natural gas prepared from coke oven gas into liquid ammonia or useless carbon monoxide in the hydrogen preparation process into hydrogen. After the conversion, a decarburization process unit is arranged to remove useless carbon dioxide in the process of preparing liquefied natural gas and co-producing liquid ammonia or hydrogen from coke oven gas. Through the combination of the processes of conversion, decarburization and demethanization, the reaction of synthesizing methane from carbon monoxide, carbon dioxide and hydrogen is greatly reduced, so that more hydrogen is reserved and the yield of liquid ammonia or hydrogen is increased. From the view of material balance, the yield of liquid ammonia can be increased by 2.83kg or 5.6Nm for each less 1kg of methane synthesized 3 Hydrogen gas.
Taking a 50000Nm3/h device for preparing LNG and co-producing liquid ammonia by using coke oven gas as an example, if the patent technology 'a process for preparing liquefied natural gas and co-producing liquid ammonia by using coke oven gas (CN 102517108A)' is adopted, 11.2 ten thousand tons of LNG and 5.0 ten thousand tons of liquid ammonia can be obtained every year; if the method is adopted, 9.2 ten thousand tons of LNG and 10.6 ten thousand tons of liquid ammonia can be obtained every year.
2) The process flow of methanation matched with cryogenic separation is adopted and is arranged after transformation and decarburization, so that the transformation reaction and CO are reduced 2 The depth of removal is required so as to meet the requirements of impurities in downstream devicesAnd under the condition of demand, the steam consumption is saved.
Compared with other similar process flows for producing LNG by using coke-oven gas, the method mainly has the following main differences that the original effective gas components in the coke-oven gas are utilized to a greater extent: hydrogen, nitrogen.
1) The process flow of co-producing liquid ammonia or hydrogen by using the cryogenic tail gas increases the yield of liquid ammonia or hydrogen.
2) The process flow for preparing liquefied natural gas by using coke oven gas generally adopts cryogenic tail gas which accounts for 20-30V% of the raw material coke oven gas. If the gas can not be well utilized, the waste of the cost such as compression power consumption, gas purification and the like can be caused, and once the gas is made into a chemical product, the economic value of the gas is considerable.
At 50000Nm 3 For example, if the patent technology of 'a method for producing liquefied natural gas from coke oven gas (CN 102115684B)' is adopted, there will be about 12500Nm 3 The deep cooling tail gas per hour is burned back without other purification cost, and the electricity wasted each year is about 1600 ten thousand degrees.
Compared with other process flows of preparing liquefied natural gas and co-producing liquid ammonia or hydrogen by using similar coke oven gas, the method has the main difference that the LNG yield and the yield of the co-produced liquid ammonia or hydrogen can be adjusted according to market conditions, so that greater economic benefit is obtained. By adjusting the reaction depth of shift and decarburization, the variation range of 90-120% of LNG yield can be obtained under the same 100% of raw gas quantity, and at the moment, the corresponding yield of liquid ammonia or hydrogen can be varied within the range of 120-60%.
Drawings
FIG. 1 is a schematic view of a process flow of producing liquefied natural gas and liquid ammonia from coke oven gas with shift decarburization.
FIG. 2 is a schematic view of a process flow of producing liquefied natural gas and co-producing hydrogen gas from coke oven gas with shift decarburization.
FIG. 3 is a schematic view of the process flow of hydrodesulfurization according to example 1 of the present invention.
Detailed Description
A technology for preparing liquefied natural gas and co-producing liquid ammonia or hydrogen by coke oven gas with conversion decarburization comprises the following steps:
1) Purification: pretreating coke oven gas to obtain primarily purified coke oven gas;
2) Hydrodesulfurization: carrying out hydrodesulfurization treatment on the primarily purified coke oven gas to remove sulfides in the coke oven gas;
3) And (3) transforming: setting a conversion and waste heat recovery unit to adjust H in the coke oven gas 2 、CO、CO 2 Obtaining the transformed gas according to the proportion;
4) Decarbonization: most of carbon dioxide in the conversion gas is removed, and the obtained decarbonized gas is sent to a methanation unit;
5) Methanation: carrying out methanation on the decarbonized gas to obtain a methane-rich gas;
6) Cryogenic separation: and (3) performing a refrigeration separation process on the methane-rich gas by using a mixed refrigerant to obtain an LNG product.
Preferably, the purification step in step 1) is: primarily removing macromolecular impurities in coke-oven gas from coking by adopting a gas-liquid separation or adsorption mode, then entering a gas holder for buffering and storage, then entering a compressor, compressing the coke-oven gas to 1.0-4.5 MPaG from normal pressure, and then sending the coke-oven gas to a purification process unit; the purification process unit mainly comprises the steps of washing, gas-liquid separation and adsorption, and impurities such as tar, naphthalene, ammonia, hydrogen cyanide and the like in the coke oven gas are removed to meet the process requirement index.
Preferably, the hydrodesulfurization in the step 2) comprises the specific steps of preheating purified coke-oven gas, sequentially entering a pre-hydrogenation reactor and a primary hydrogenation reactor to remove oxygen in the coke-oven gas, converting most organic sulfur into inorganic sulfur, and entering a primary medium-temperature zinc oxide tank to remove hydrogen sulfide in the coke-oven gas; the coke-oven gas from the first-stage medium-temperature zinc oxide tank enters a second-stage hydrogenation reactor to further convert organic sulfur into inorganic sulfur, and then the sulfur content in the coke-oven gas is removed through the second-stage medium-temperature zinc oxide tank.
Preferably, the total sulfur in the coke oven gas after desulfurization in the step 2) is reduced to less than or equal to 0.1ppmv.
Preferably, the conversion specific step in the step 3) is that the desulfurized gas is subjected to waste heat recovery, proper water vapor is added, the desulfurized gas enters the conversion reactor, and the converted gas is sent to the decarburization unit after byproduct steam and heat are recovered.
Preferably, the dry basis index of carbon monoxide in the shift gas obtained in step 3) is 0.2V% to 1.5V%.
Preferably, in step 4), the gas is decarbonated using an MDEA solution.
Preferably, the index of carbon dioxide in the decarbonated gas obtained in step 4) is 0.1 to 1.5V%.
Preferably, the methanation in the step 5) comprises the specific steps that the decarbonized gas is preheated and then enters a methanation reactor, the methane-rich gas at the outlet of the methanation reactor enters a second-stage methanation reactor after byproduct steam and waste heat are recovered, and CO + CO at the outlet of the second-stage methanation reactor 2 Less than or equal to 20ppm; after waste heat recovery, the waste heat is cooled to 40 ℃ by using circulating water to obtain methane-rich gas, and the methane-rich gas mainly comprises 30-80V% of hydrogen, 20-60V% of methane and 3-8V% of nitrogen.
Preferably, the specific step of deep cooling separation in the step 6) is that the methane-rich gas enters a cooling box after being subjected to deep cooling pretreatment to remove moisture, dust and other trace harmful impurities; and carrying out cryogenic separation to obtain an LNG product.
The present invention is further illustrated by the following examples in order to better explain the context of the invention, but it should not be understood that the scope of the invention is limited thereto and that all features disclosed in the summary of the invention, or all steps in the methods or processes disclosed, may be combined in any way, except mutually exclusive features and/or steps. Any feature disclosed in this application may be replaced by alternative features serving equivalent or similar purposes, unless expressly stated otherwise. That is, unless expressly stated otherwise, each feature is only an example of a generic series of equivalent or similar features.
In the present application, all% refer to V% unless otherwise specified.
Example 1
Boundary entering areaCoke oven gas 40 deg.C, 6kPaG pressure and 49724Nm gas amount 3 On a dry basis, hydrogen 58.07%, carbon monoxide 6.45%, carbon dioxide 2.15%, methane 25.81%, oxygen 0.54%, cnHm2.48%, and an impurity composition (mg/Nm) on a dry basis 3 ): 100 parts of tar, 200 parts of naphthalene, 50 parts of ammonia, 50 parts of hydrogen sulfide, 150 parts of organic sulfur, 150 parts of hydrogen cyanide, and 2500 parts of C6 and above hydrocarbons.
1) Compression purification
Coke oven gas from coking is pretreated, and tar in the coke oven gas is removed to 5mg/Nm by gas-liquid separation or adsorption 3 Naphthalene is removed to 50mg/Nm 3 After the coke oven gas enters a gas holder for buffering and storage, the coke oven gas enters a plurality of parallel reciprocating compressors with the pressure of about 3-4 kPaG, the reciprocating compressors adopt four-stage compression, the coke oven gas can be compressed from normal pressure to 2.4MPaG, then the coke oven gas is sent to a purification unit, and the tar in the coke oven gas is further removed to 1mg/Nm 3 Following, naphthalene was removed to 5mg/Nm 3 The following.
2) Hydrodesulfurization
The coke oven gas from the compressor is washed by water to remove ammonia to 5mg/Nm 3 Hydrocyanic acid is removed to 1mg/Nm 3 The following. Then preheating to about 240 ℃, sequentially entering a pre-hydrogenation reactor and a first-stage hydrogenation reactor, removing oxygen in the coke-oven gas, simultaneously converting 90% of organic sulfur into inorganic sulfur, and then entering a first-stage medium-temperature zinc oxide tank to remove hydrogen sulfide in the coke-oven gas. The coke oven gas from the first-stage medium-temperature zinc oxide tank enters a second-stage hydrogenation reactor to further convert organic sulfur into inorganic sulfur, and then the total sulfur content in the coke oven gas is removed to be below 0.1ppm through the second-stage medium-temperature zinc oxide tank.
3) Transformation
After waste heat recovery and addition of proper amount of water vapor, the desulfurized gas enters a wide temperature shift reactor after the temperature is reduced to 230 ℃. The converted gas is about 280 ℃, and is sent to a downstream process after byproduct steam and heat are recovered. The main gas components of the time-varying ventilation gas are 59.52% of hydrogen, 0.60% of carbon monoxide, 7.82% of carbon dioxide and 25.25% of methane.
4) Decarburization of carbon
The scrubbing gas is decarbonized by adopting an MDEA solution, and the main gas components of the decarbonized process gas are 64.44 percent of hydrogen, 0.65 percent of carbon monoxide, 0.20 percent of carbon dioxide and 27.33 percent of methane.
5) Methanation of
Preheating the decarbonized gas to 360-385 ℃, then feeding the decarbonized gas into a methanation reactor, wherein the outlet of the methanation reactor is 485-515 ℃, recycling byproduct steam and waste heat, then feeding the decarbonized gas into a second-stage methanation reactor, and feeding CO and CO at the outlet of the second-stage methanation reactor 2 Less than or equal to 20ppm. After waste heat recovery, the waste heat is cooled to 40 ℃ by using circulating water to obtain methane-rich gas, and the methane-rich gas mainly comprises 60.51% of hydrogen and 34.60% of methane. The amount of methane-rich gas is about 45752Nm 3 /h。
6) Cryogenic separation
The methane-rich gas enters a drying tower from the lower part, and the water in the dried gas from the upper part is removed to below 1ppm for cryogenic separation. The regeneration gas of the drying tower adopts nitrogen-rich gas of cryogenic separation and nitrogen gas from air separation. Then a mixed refrigerant refrigeration separation process is adopted to obtain an LNG product of 11.31t/h, the cryogenic tail gas of the byproduct is divided into two streams, one stream of hydrogen-rich gas is directly sent to an ammonia synthesis unit to be used as raw material gas, and the other stream of nitrogen-rich gas is used as regeneration gas of a drying unit.
7) Ammonia synthesis
After being pressurized by a nitrogen compressor, the nitrogen-rich gas from the dry regenerated gas is mixed with the hydrogen-rich gas from the cryogenic separation, and then the mixture enters an ammonia synthesis gas compressor, and enters an ammonia synthesis unit after being pressurized, so that a liquid ammonia product is obtained at 13.71t/h.
Example 2
Coke oven gas entering boundary region at 40 deg.c, 6kPaG pressure and 49724Nm gas amount 3 On a dry basis, hydrogen 58.07%, carbon monoxide 6.45%, carbon dioxide 2.15%, methane 25.81%, oxygen 0.54%, cnHm2.48%, and an impurity composition (mg/Nm) on a dry basis 3 ): 100 parts of tar, 200 parts of naphthalene, 50 parts of ammonia, 50 parts of hydrogen sulfide, 150 parts of organic sulfur, 150 parts of hydrogen cyanide, and 2500 parts of C6 and above hydrocarbons.
1) Compression purification (same example 1)
The coke oven gas from coking is pretreated, and tar in the coke oven gas is removed in a gas-liquid separation or adsorption mode5mg/Nm 3 Naphthalene is removed to 50mg/Nm 3 After the coke oven gas enters a gas holder for buffering and storage, the coke oven gas enters a plurality of parallel reciprocating compressors with the pressure of 3-4 kPaG, the reciprocating compressors adopt four-stage compression, the coke oven gas can be compressed from normal pressure to 2.4MPaG, then the coke oven gas is sent to a purification unit, and the tar in the coke oven gas is further removed to 1mg/Nm 3 As follows, naphthalene desorption was to 5mg/Nm 3 The following.
2) Hydrodesulfurization (same as in example 1)
The coke oven gas from the compressor is washed by water to remove ammonia to 5mg/Nm 3 Hydrocyanic acid is removed to 1mg/Nm 3 The following. Then preheating to about 240 ℃, sequentially entering a pre-hydrogenation reactor and a primary hydrogenation reactor, removing oxygen in the coke-oven gas, simultaneously converting 90% of organic sulfur into inorganic sulfur, and then entering a primary medium-temperature zinc oxide tank to remove hydrogen sulfide in the coke-oven gas. The coke oven gas from the first-stage medium-temperature zinc oxide tank enters a second-stage hydrogenation reactor to further convert organic sulfur into inorganic sulfur, and then the total sulfur content in the coke oven gas is removed to be below 0.1ppm through the second-stage medium-temperature zinc oxide tank.
3) The main gas components of the converted gas are 58.18% of hydrogen, 3.93% of carbon monoxide, 4.76% of carbon dioxide and 26.08% of methane by adjusting the steam-water ratio of the conversion.
4) The decarbonization is carried out by adopting MDEA solution, and the main gas components in the decarbonization gas comprise 60.48 percent of hydrogen gas, 4.08 percent of carbon monoxide, 0.99 percent of carbon dioxide and 27.11 percent of methane.
5) Methanation
Preheating the decarbonization gas to 270-305 ℃, then feeding the decarbonization gas into a methanation reactor, wherein the outlet of the methanation reactor is 510-540 ℃, recycling byproduct steam and waste heat, then feeding the decarbonization gas into a second-stage methanation reactor, and feeding CO + CO at the outlet of the second-stage methanation reactor 2 Less than or equal to 20ppm. After waste heat recovery, the waste heat is cooled to 40 ℃ by using circulating water to obtain methane-rich gas, and the methane-rich gas mainly comprises 49.47% of hydrogen and 44.90% of methane. The amount of methane-rich gas is about 39731Nm 3 /h。
6) The LNG product 12.74t/h is obtained by adopting a mixed refrigerant refrigeration separation process, the cryogenic tail gas of the byproduct is divided into two streams, one stream of hydrogen-rich gas is directly sent to an ammonia synthesis unit to be used as raw material gas, and the other stream of nitrogen-rich gas is used as regeneration gas of a drying unit.
7) After being pressurized by a nitrogen compressor, the nitrogen-rich gas from the dry regenerated gas is mixed with the hydrogen-rich gas from the cryogenic separation, and then the mixture enters an ammonia synthesis gas compressor, and enters an ammonia synthesis unit after being pressurized, so that a liquid ammonia product of 9.73t/h is obtained.
Example 3
Coke oven gas entering boundary region at 40 deg.c, 6kPaG pressure and 49724Nm gas amount 3 Dry basis of hydrogen 58.07%, carbon monoxide 6.45%, carbon dioxide 2.15%, methane 25.81%, oxygen 0.54%, cnHm2.48%, and impurities (mg/Nm/g) 3 ): 100 parts of tar, 200 parts of naphthalene, 50 parts of ammonia, 50 parts of hydrogen sulfide, 150 parts of organic sulfur, 150 parts of hydrogen cyanide, and 2500 parts of C6 and above hydrocarbons.
1) Compressed purification (same example 1)
Coke oven gas from coking is pretreated, and tar in the coke oven gas is removed to 5mg/Nm by gas-liquid separation or adsorption 3 Naphthalene is removed to 50mg/Nm 3 After the coke oven gas enters a gas holder for buffering and storage, the coke oven gas enters a plurality of parallel reciprocating compressors with the pressure of about 3-4 kPaG, the reciprocating compressors adopt four-stage compression, the coke oven gas can be compressed from normal pressure to 2.4MPaG, then the coke oven gas is sent to a purification unit, and the tar in the coke oven gas is further removed to 1mg/Nm 3 Following, naphthalene was removed to 5mg/Nm 3 The following.
2) Hydrodesulfurization (same as in example 1)
Removing ammonia in coke oven gas from a compressor to 5mg/Nm through water washing 3 Hydrocyanic acid is removed to 1mg/Nm 3 The following. Then preheating to about 240 ℃, sequentially entering a pre-hydrogenation reactor and a primary hydrogenation reactor, removing oxygen in the coke-oven gas, simultaneously converting 90% of organic sulfur into inorganic sulfur, and then entering a primary medium-temperature zinc oxide tank to remove hydrogen sulfide in the coke-oven gas. The coke oven gas from the first-stage medium-temperature zinc oxide tank enters a second-stage hydrogenation reactor to further convert organic sulfur into inorganic sulfur, and then the total sulfur content in the coke oven gas is removed to be below 0.1ppm through the second-stage medium-temperature zinc oxide tank.
3) Transformations (in the same example 1)
After waste heat recovery and addition of proper amount of water vapor, the desulfurized gas enters a wide temperature shift reactor after the temperature is reduced to 230 ℃. The converted gas is about 280 ℃, and is sent to a downstream process after byproduct steam and heat are recovered. The main gas components of the time-varying ventilation gas are 59.52% of hydrogen, 0.60% of carbon monoxide, 7.82% of carbon dioxide and 25.25% of methane.
4) Decarbonization (same example 1)
The scrubbing gas is decarbonized by adopting an MDEA solution, and the main gas components of the decarbonized process gas are 64.44 percent of hydrogen, 0.65 percent of carbon monoxide, 0.20 percent of carbon dioxide and 27.33 percent of methane.
5) Methanation (as in example 1)
Preheating the decarbonized gas to 360-385 ℃, then feeding the decarbonized gas into a methanation reactor, wherein the outlet of the methanation reactor is 485-515 ℃, recycling byproduct steam and waste heat, then feeding the decarbonized gas into a second-stage methanation reactor, and feeding CO and CO at the outlet of the second-stage methanation reactor 2 Less than or equal to 20ppm. After waste heat recovery, the waste heat is cooled to 40 ℃ by using circulating water to obtain methane-rich gas, and the methane-rich gas mainly comprises 60.51% of hydrogen and 34.60% of methane. The amount of methane-rich gas is about 45752Nm 3 /h。
6) Cryogenic separation (same example 1)
The methane-rich gas enters a drying tower from the lower part, and the water in the dried gas from the upper part is removed to below 1ppm for cryogenic separation. The regeneration gas of the drying tower adopts nitrogen-rich gas of cryogenic separation and nitrogen gas from air separation. Then, a mixed refrigerant refrigeration separation process is adopted to obtain 11.31t/h LNG product, the by-product cryogenic tail gas is reheated and then sent to a PSA hydrogen extraction device, the total amount is 30241Nm3/h, and the main gas components are 91.54% of hydrogen, 7.40% of nitrogen and 1.06% of methane. .
7) The tail gas from the cryogenic separation enters a PSA hydrogen extraction adsorption tower, and a hydrogen product (99.99%) 25705Nm3/h can be obtained. The desorbed gas is about 4536Nm3/h and is used as dry regenerated gas which is returned to the coke oven for fuel.
Example 4
Coke oven gas entering boundary region at 40 deg.c, 6kPaG pressure and 49724Nm gas amount 3 Hydrogen,/h (dry basis), composition on dry basis (V%)58.07%, carbon monoxide 6.45%, carbon dioxide 2.15%, methane 25.81%, oxygen 0.54%, cnHm2.48%, and impurity composition (mg/Nm) 3 ): 100 parts of tar, 200 parts of naphthalene, 50 parts of ammonia, 50 parts of hydrogen sulfide, 150 parts of organic sulfur, 150 parts of hydrogen cyanide, and 2500 parts of C6 and above hydrocarbons.
1) Compressed purification (same as example 2)
Coke oven gas from coking is pretreated, and tar in the coke oven gas is removed to 5mg/Nm by gas-liquid separation or adsorption 3 Naphthalene was removed to 50mg/Nm 3 After the coke oven gas enters a gas holder for buffering and storage, the coke oven gas enters a plurality of parallel reciprocating compressors with the pressure of 3-4 kPaG, the reciprocating compressors adopt four-stage compression, the coke oven gas can be compressed from normal pressure to 2.4MPaG, then the coke oven gas is sent to a purification unit, and the tar in the coke oven gas is further removed to 1mg/Nm 3 Following, naphthalene was removed to 5mg/Nm 3 The following.
2) Hydrodesulfurization (same as in example 2)
The coke oven gas from the compressor is washed by water to remove ammonia to 5mg/Nm 3 Hydrocyanic acid is removed to 1mg/Nm 3 The following. Then preheating to about 240 ℃, sequentially entering a pre-hydrogenation reactor and a first-stage hydrogenation reactor, removing oxygen in the coke-oven gas, simultaneously converting 90% of organic sulfur into inorganic sulfur, and then entering a first-stage medium-temperature zinc oxide tank to remove hydrogen sulfide in the coke-oven gas. The coke oven gas from the first-stage medium-temperature zinc oxide tank enters a second-stage hydrogenation reactor to further convert organic sulfur into inorganic sulfur, and then the total sulfur content in the coke oven gas is removed to be below 0.1ppm through the second-stage medium-temperature zinc oxide tank.
3) Alternative (same as example 2)
The main gas components of the converted gas are 58.18% of hydrogen, 3.93% of carbon monoxide, 4.76% of carbon dioxide and 26.08% of methane by adjusting the steam-water ratio of the conversion.
4) Decarburization (same as example 2)
The decarbonization is carried out by adopting MDEA solution, and the main gas components in the decarbonization gas comprise 60.48 percent of hydrogen, 4.08 percent of carbon monoxide, 0.99 percent of carbon dioxide and 27.11 percent of methane.
5) Methanation (as in example 2)
Preheating the decarbonization gas to 270-305 ℃, then feeding the decarbonization gas into a methanation reactor, wherein the outlet of the methanation reactor is 510-540 ℃, recycling byproduct steam and waste heat, then feeding the decarbonization gas into a second-stage methanation reactor, and feeding CO + CO at the outlet of the second-stage methanation reactor 2 Less than or equal to 20ppm. After waste heat recovery, the waste heat is cooled to 40 ℃ by using circulating water to obtain methane-rich gas, and the methane-rich gas mainly comprises 49.47% of hydrogen and 44.90% of methane. The amount of methane-rich gas is about 39731Nm 3 /h。
6) Cryogenic separation (same as example 2)
The LNG product 12.74t/h is obtained by adopting a mixed refrigerant refrigeration separation process, the by-product cryogenic tail gas is reheated and then sent to a PSA hydrogen extraction device, and the total amount is 22123Nm 3 The main gas components are 88.85 percent of hydrogen, 10.11 percent of nitrogen and 1.04 percent of methane. .
7) The tail gas from the cryogenic separation enters a PSA hydrogen extraction adsorption tower to obtain a hydrogen product (99.99 percent) 18804Nm 3 H is used as the reference value. The desorbed gas is about 3319Nm3/h, is used as dry regenerated gas, and is returned to the coke oven to be used as fuel after regeneration.
The invention is not limited to the foregoing embodiments. The invention extends to any novel feature or any novel combination of features disclosed in this specification and any novel method or process steps or any novel combination of features disclosed.

Claims (5)

1. A technology for preparing liquefied natural gas and co-producing liquid ammonia or hydrogen by coke oven gas with conversion decarburization is characterized by comprising the following steps:
1) Purifying: pretreating the coke-oven gas to obtain primarily purified coke-oven gas;
2) Hydrodesulfurization: carrying out hydrodesulfurization treatment on the primarily purified coke oven gas to remove sulfides in the coke oven gas; the specific steps of hydrodesulfurization are that purified coke-oven gas is preheated and then sequentially enters a pre-hydrogenation reactor and a primary hydrogenation reactor to remove oxygen in the coke-oven gas, most organic sulfur is converted into inorganic sulfur at the same time, and then the hydrogen sulfide in the coke-oven gas is removed in a primary medium-temperature zinc oxide tank; the coke-oven gas from the first-stage medium-temperature zinc oxide tank enters a second-stage hydrogenation reactor to further convert organic sulfur into inorganic sulfur, and then the sulfur content in the coke-oven gas is removed through the second-stage medium-temperature zinc oxide tank; reducing the total sulfur in the desulfurized coke-oven gas to be less than or equal to 0.1ppmv;
3) And (3) transforming: setting a conversion and waste heat recovery unit to adjust H in the coke oven gas 2 、CO、CO 2 Obtaining the transformed gas according to the proportion; the conversion comprises the specific steps that the desulfurized gas enters a conversion reactor after being subjected to waste heat recovery and added with proper water vapor, and the converted gas is sent to a decarburization unit after being subjected to byproduct steam and heat recovery; in the obtained conversion gas, the dry basis index of the carbon monoxide is 0.2V% -1.5V%;
4) Decarbonizing: most of carbon dioxide in the shift gas is removed, and the obtained decarbonized gas is sent to a methanation unit; the index of carbon dioxide in the obtained decarbonized gas is 0.1V-1.5V%;
5) Methanation: carrying out methanation on the decarbonized gas to obtain a methane-rich gas;
6) Cryogenic separation: and (3) performing a refrigeration separation process on the methane-rich gas by using a mixed refrigerant to obtain an LNG product.
2. The process for preparing liquefied natural gas and co-producing liquid ammonia or hydrogen gas by using coke oven gas with shift decarburization as claimed in claim 1, wherein the purification step in step 1) is: primarily removing macromolecular impurities in coke oven gas from coking by adopting a gas-liquid separation or adsorption mode, then entering a gas holder for buffering and storage, then entering a compressor, compressing the coke oven gas to 1.0-4.5 MPaG from normal pressure, and then sending the coke oven gas to a purification process unit; the purification process unit mainly comprises the steps of washing, gas-liquid separation and adsorption, and impurities such as tar, naphthalene, ammonia, hydrogen cyanide and the like in the coke oven gas are removed to the process requirement index.
3. The process for preparing liquefied natural gas and co-producing liquid ammonia or hydrogen gas by using coke oven gas with shift decarburization as claimed in claim 1, wherein the shift gas in step 4) is decarbonized by using MDEA solution.
4. The tape changer of claim 1The process for preparing liquefied natural gas and CO-producing liquid ammonia or hydrogen by using carbon coke oven gas is characterized in that the methanation in the step 5) specifically comprises the steps of preheating decarbonized gas and then entering a methanation reactor, recycling byproduct steam and waste heat of methane-rich gas at the outlet of the methanation reactor and then entering a second-stage methanation reactor, and recycling CO + CO at the outlet of the second-stage methanation reactor 2 Less than or equal to 20ppm; after waste heat recovery, the waste heat is cooled to 40 ℃ by using circulating water to obtain methane-rich gas, and the methane-rich gas mainly comprises 30-80V% of hydrogen, 20-60V% of methane and 3-8V% of nitrogen.
5. The process for preparing liquefied natural gas and co-producing liquid ammonia or hydrogen gas by using the coke oven gas with shift decarburization as claimed in claim 1, wherein the specific step of deep cooling separation in step 6) is that the methane-rich gas is subjected to deep cooling pretreatment, and enters a cooling box after moisture, micro dust and other trace harmful impurities are removed; and carrying out cryogenic separation to obtain an LNG product.
CN202111272968.6A 2021-10-29 2021-10-29 Process for preparing liquefied natural gas and co-producing liquid ammonia or hydrogen by coke oven gas with conversion decarburization Active CN114149837B (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
CN202111272968.6A CN114149837B (en) 2021-10-29 2021-10-29 Process for preparing liquefied natural gas and co-producing liquid ammonia or hydrogen by coke oven gas with conversion decarburization

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
CN202111272968.6A CN114149837B (en) 2021-10-29 2021-10-29 Process for preparing liquefied natural gas and co-producing liquid ammonia or hydrogen by coke oven gas with conversion decarburization

Publications (2)

Publication Number Publication Date
CN114149837A CN114149837A (en) 2022-03-08
CN114149837B true CN114149837B (en) 2022-11-15

Family

ID=80459153

Family Applications (1)

Application Number Title Priority Date Filing Date
CN202111272968.6A Active CN114149837B (en) 2021-10-29 2021-10-29 Process for preparing liquefied natural gas and co-producing liquid ammonia or hydrogen by coke oven gas with conversion decarburization

Country Status (1)

Country Link
CN (1) CN114149837B (en)

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN113955716A (en) * 2020-06-29 2022-01-21 杨皓 Process for preparing synthetic gas and CNG (compressed natural gas) from coke-oven gas submerged arc furnace gas
CN115572213A (en) * 2022-11-08 2023-01-06 中国平煤神马控股集团有限公司 Process for coproduction of 1, 4-butanediol and liquid ammonia by coal gasification coupled with coal coking

Family Cites Families (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN112897464B (en) * 2021-01-18 2022-05-17 西南化工研究设计院有限公司 Process for producing hydrogen and coproducing LNG (liquefied natural gas) by using raw gas with methanation

Also Published As

Publication number Publication date
CN114149837A (en) 2022-03-08

Similar Documents

Publication Publication Date Title
CN114149837B (en) Process for preparing liquefied natural gas and co-producing liquid ammonia or hydrogen by coke oven gas with conversion decarburization
CN112897464B (en) Process for producing hydrogen and coproducing LNG (liquefied natural gas) by using raw gas with methanation
CN101575540B (en) Method for producing liquefied natural gas and carbinol simultaneously
CN102776042A (en) Method for producing liquefied natural gas (LNG) by using semi-coke tail gas
CN102642810B (en) Combined process for preparing Fischer-Tropsch synthetic oil raw material gas by utilizing coke-oven gas
CN102942970A (en) Combination method using semi-coke tail gas for power generation to cogenerate liquefied natural gas
CN103303863A (en) Method for producing ammonia synthesis gas from coke-oven gas
CN103407963A (en) Coke oven gas hydrogen generation process
CN102585951A (en) Novel process for co-production of liquefied synthesis gas, pure hydrogen and methanol from coke-oven gas
CN103803492B (en) The method of low temperature pyrogenation coal gas hydrogen manufacturing cogeneration LNG
CN217459345U (en) Device for producing low-carbon methanol by using coke oven gas
CN102732347A (en) Adjustable process for co-producing liquefied natural gas and hydrogen by coke furnace gas
CN105293436A (en) Process for preparation of metallurgical reduction gas and co-production of liquefied natural gas through coke gas
CN104974014B (en) A kind of method for producing methanol
CN103571558A (en) Method for preparing liquefied natural gas (LNG) from tail gas produced by external-heat destructive distillation-type semicoke preparation
CN110655939B (en) System and method for preparing LNG (liquefied Natural gas) from medium-low temperature carbonization raw gas through sulfur-resistant uniform temperature methanation
CN103496701A (en) Device for preparing carbon monoxide from coke oven gas and manufacturing method thereof
CN104974810A (en) Method for producing liquefied natural gas (LNG) from semi-coke exhaust and calcium carbide furnace gas
CN210885949U (en) System for preparing LNG (liquefied Natural gas) by sulfur-resistant uniform-temperature methanation of medium-low-temperature dry distillation raw gas
CN211005244U (en) System for preparing CNG (compressed natural gas) from medium-low temperature dry distillation raw gas through sulfur-resistant uniform-temperature methanation
CN113249147A (en) Improved process for coproducing LNG (liquefied Natural gas) and synthetic ammonia from coke oven gas
CN212316051U (en) Poly-generation device for producing natural gas by using underground gasified gas
CN106566574A (en) Method for producing Fischer-Tropsch chemicals by using coke oven gas and converter gas
CN110926106A (en) Liquefaction process for preparing LNG
CN215404060U (en) Device for coproduction of liquefied natural gas and synthetic ammonia by methanation of coke oven gas

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