CN214243809U

CN214243809U - System for producing hydrogen and coproducing LNG (liquefied Natural gas) by using raw gas

Info

Publication number: CN214243809U
Application number: CN202023225253.9U
Authority: CN
Inventors: 侯世杰; 余浩; 瞿孝星; 曾轲; 李振东; 梁东; 黄成波; 阎朝旭; 邹康; 刘贤虎
Original assignee: Chengdu Huaxi Chemical Technology Co ltd; Chengdu Yizhi Technology Co ltd
Current assignee: Chengdu Huaxi Chemical Technology Co ltd; Chengdu Yizhi Technology Co ltd
Priority date: 2020-12-28
Filing date: 2020-12-28
Publication date: 2021-09-21
Anticipated expiration: 2030-12-28

Abstract

The utility model discloses a raw coke oven gas hydrogen manufacturing coproduction LNG system, prepare the unit including decoking unit, pressure boost unit, preprocessing unit, deoxidation transform unit, desulfurization unit, decarbonization unit, methane concentration unit, hydrogen purification unit, LNG. In the system for producing hydrogen and co-producing LNG by using the raw gas, LNG is produced while hydrogen is produced, so that effective components in the raw gas are fully utilized, and the waste of energy is reduced; in addition, the utility model completes the pressurization of the raw coke oven gas through three times of compression in different stages, thereby reducing the compression energy consumption; in addition, the utility model adopts two-stage vacuum-pumping pressure swing adsorption to remove impurities in the raw coke oven gas after CO conversion to obtain the product hydrogen with the purity of 99.9 percent, and the recovery rate of the hydrogen can reach more than 89 percent; wherein the desorbed gas rich in methane, which is desorbed from the first-stage vacuum pressure swing adsorption, is used for preparing LNG.

Description

System for producing hydrogen and coproducing LNG (liquefied Natural gas) by using raw gas

Technical Field

The utility model relates to a raw coke oven gas handles technical field, concretely relates to raw coke oven gas hydrogen manufacturing coproduction LNG system.

Background

The raw gas is also called raw gas and coke oven gas, is gas which is generated by low-temperature dry distillation of coal and is not subjected to purification treatment, and the main components of the raw gas are shown in the following table:

composition of	Raw gas (mol%)
		O₂	0.5～1.0
N ₂	20～45
		H ₂	10～30
CO	10～20
		CO ₂	10～20
CH ₄	5～10
		CmHn	0.5～2
Water (W)	Saturated water

The raw gas contains a small amount of tar, benzene, naphthalene, hydrogen sulfide, organic sulfur, HCN, NH, in addition to the components in the table₃And the like. The content of impurities in the relatively common raw gas is shown in the following table:

the raw coke oven gas has certain components according to the coal quality and the treatment process.

At present, most of raw gas is directly used as fuel, such as fuel of a pyrolysis furnace and power generation fuel, and the raw gas cannot be fully utilized, so that great resource waste is caused. In addition, the content of sulfide in the raw gas is high, and the direct emission of the tail gas generated by burning the raw gas as a fuel inevitably causes serious pollution to the environment. If the tail gas generated by burning the raw gas is discharged after being treated, the cost of the whole process is increased, and the industrial development is not facilitated.

For the reasons, research and development personnel research the later utilization of the raw coke oven gas with the purposes of not wasting resources and reducing the cost of the process. "application number is: 201810320196.0, the patent names: a raw gas hydrogen production process' discloses a high-purity hydrogen product obtained by sequentially compressing raw gas, washing with water to remove salt, pretreating, carrying out sulfur-resistant wide-temperature shift (whether the raw gas is adopted or not is determined according to the hydrogen demand of the whole set of device), carrying out pressure swing adsorption to concentrate hydrogen, carrying out pressure swing adsorption to purify hydrogen, integrating wet desulphurization process units and the like. "application number: 201610699330.3, the patent names: the patent discloses a low-energy-consumption high-yield raw gas hydrogen production method, which can further process raw gas so as to obtain hydrogen and nitrogen with higher economic values. "application number: 201810042063.1, the patent names: a method for preparing hydrogen and LNG by coke oven gas, and the application number: 201510850839.9, the patent names: a process for preparing metallurgical reducing gas and coproducing liquefied natural gas by utilizing coke oven gas' records that the coke oven gas after pretreatment (the pretreatment comprises decoking, TSA impurity removal, desulfurization and CO conversion) is separated by a membrane separation method to prepare hydrogen and methane;

although the above patent documents describe different processing methods for raw gas, and the raw gas is processed by the technical methods described in the above patent documents, products with higher economic value, such as hydrogen, nitrogen, LNG (liquefied natural gas), etc., can be obtained. However, the above-mentioned several processes for processing raw gas still have some problems, as follows:

(1) patent document "application number: 201810320196.0, the patent names: the technical scheme recorded in the 'raw gas hydrogen production process' can only extract hydrogen in raw gas, and other components in the raw gas are wasted.

(2) Patent document "application No.: 201810042063.1, the patent names: a method for preparing hydrogen and LNG by coke oven gas and application number: 201510850839.9, the patent names: the technical scheme recorded in the process for preparing the metallurgical reducing gas and coproducing the liquefied natural gas by using the coke oven gas can simultaneously prepare hydrogen and LNG, fully utilizes valuable components in the raw coke oven gas, but separates the hydrogen and the methane by using a membrane separation method, the pressure of the obtained product hydrogen is very low, the pressure of the general product hydrogen is 1/4 of the inlet pressure, so that the hydrogen is required to be compressed again in the follow-up process, and the energy consumption of the device is greatly improved. And because the content of effective components in the raw gas is not high, the whole treatment process is complex, and the scale of the raw gas is large in order to reduce the production cost of unit product gas. The scale of membrane separation is a combination of modular blocks, so as the scale increases, the investment increases proportionally. Therefore, in the crude gas hydrogen production device, the investment of membrane separation is much larger than that of the pressure swing adsorption process.

(3) Because the pressure of raw gas is lower and is only a few kilopascals generally and the content of impurities is complex, the raw gas needs to be pressurized to a certain pressure and then subjected to subsequent treatment, but according to the records of the prior art, the compression energy consumption in the operation process is large.

Therefore, the technical field of raw gas treatment urgently needs a product which can improve the utilization rate of beneficial components in raw gas and obtain higher economic value from the raw gas; and simultaneously, the raw coke oven gas treatment process can reduce the cost of prepared products and improve the yield of products with higher economic value.

SUMMERY OF THE UTILITY MODEL

In order to improve the utilization rate of beneficial components in the raw gas, a product with higher economic value is obtained from the raw gas; meanwhile, the cost of preparing a product with high economic value from the raw gas is reduced, the product yield with higher economic value is improved, the economic value benefit maximization of the raw gas is realized, and the utility model provides a raw gas hydrogen production and LNG co-production system.

In order to achieve the above object, the utility model adopts the following technical scheme:

a raw gas hydrogen production and LNG cogeneration system comprises a decoking unit, a primary pressurizing cooling liquid separation unit, a secondary pressurizing unit, a pretreatment unit, a tertiary pressurizing unit, a deoxidation conversion unit, a desulfurization unit, a decarburization unit, a methane concentration unit, a hydrogen purification unit and an LNG preparation unit which are sequentially communicated;

wherein the decoking unit: the method is used for removing tar in raw material raw gas to obtain decoking raw gas;

the primary pressurizing and cooling liquid separation unit comprises: the system is used for pressurizing the coke-removing raw gas, sequentially cooling and separating the pressurized raw gas to obtain primary pressurized raw gas;

the secondary pressurization unit: the system is used for pressurizing the primary pressurized raw gas and obtaining secondary pressurized raw gas;

the preprocessing unit: for removing NH in secondary supercharged raw gas₃Further removing tar, benzene and naphthalene in the secondary pressurized raw coke oven gas to finally obtain purified raw coke oven gas;

the third supercharging unit: used for pressurizing the purified raw coke oven gas;

the deoxidation conversion unit: is used for deoxidizing the pressurized purified raw gas and leading CO in the deoxidized raw gas to have a shift reaction with water vapor to generate H₂And CO₂Finally obtaining transformed raw gas;

the desulfurization unit: for removing H in transformed raw gas₂S, finally obtaining desulfurized raw gas;

the decarbonization unit: for removing the impuritiesCO in sulfur raw gas₂Finally, obtaining decarbonized raw gas;

the methane concentration unit: the methane removing device is used for removing methane in the decarbonized raw gas to obtain a crude product hydrogen and a desorption gas rich in methane;

the hydrogen purification unit: further purifying the crude product hydrogen to obtain a product hydrogen;

the LNG production unit: and preparing the desorbed gas rich in methane into LNG.

Further, the decoking unit is an electrostatic decoking device.

Further, the primary pressurizing, cooling and liquid separating unit comprises an air blower for pressurizing the decoking raw gas, a first cooler communicated with the air blower and used for cooling the pressurized decoking raw gas, and a first liquid separator communicated with the first cooler and used for separating the cooled decoking raw gas to obtain the primary pressurizing raw gas;

the secondary pressurization unit comprises a screw compressor which is communicated with the first liquid separator and is used for pressurizing the primary pressurized raw coke oven gas.

Further, the pretreatment unit comprises a water washing unit and a TSA purification unit which are sequentially communicated; the water washing unit comprises a water washing tower used for washing the secondary supercharged raw gas after supercharging and obtaining deamination raw gas, and the TSA purification unit comprises a temperature swing adsorption tower used for further removing tar, benzene and naphthalene in the deamination raw gas to obtain purified raw gas; wherein, the temperature swing adsorption tower is at least 2.

Further, the tertiary pressurization unit is a centrifugal compressor which is communicated with the TSA purification unit and is used for pressurizing the purified raw gas.

Further, the deoxidation conversion unit comprises a preheater for preheating the pressurized purified raw gas, a purification furnace communicated with the preheater for removing toxic substances and oxygen in the purified raw gas, a humidifier communicated with the purification furnace for increasing the water-to-gas ratio in the purified raw gas while reducing the temperature of the purified raw gas by spraying water, and a humidifier communicated with the humidifier for promoting the conversion of CO and water vaporIs H₂And CO₂The two-stage shift converter.

Further, the desulfurization unit comprises a device for converting H in the raw gas₂The wet desulphurization system for S removal is communicated with the wet desulphurization system and is used for further converting H in the raw coke oven gas₂And a dry desulfurization system for S removal.

Further, the decarbonization unit comprises a device for removing CO in the desulfurized raw gas₂And an absorption tower for obtaining decarbonized raw gas, which is communicated with the absorption tower and is used for absorbing CO₂A regeneration tower for regenerating the absorption liquid.

Further, the methane concentration unit is a vacuum-pumping pressure swing adsorption system I which adsorbs methane in the decarbonized raw gas and obtains a crude product hydrogen; wherein, the crude product hydrogen from the vacuumizing pressure swing adsorption system I enters a hydrogen purification unit, and the adsorbed methane enters an LNG preparation unit after being desorbed.

Further, the hydrogen purification unit is a vacuum-pumping pressure swing adsorption system II for further separating and purifying the crude product hydrogen.

Further, the LNG preparation unit comprises a pressurization system, a drying device, a demercuration device and a cold box which are sequentially communicated; wherein, methane is desorbed and then sequentially passes through a pressurizing system, a drying device, a demercuration device and a cold box to be prepared into LNG.

Compared with the prior art, the utility model discloses following beneficial effect has:

(1) utilize raw coke oven gas to prepare hydrogen and coproduction LNG system in, can divide two stages of construction at the construction in-process, wherein, decoking unit, pressure boost cooling divide liquid unit, secondary pressure boost unit, preprocessing unit, cubic pressure boost unit, deoxidation transform unit, desulfurization unit, methane concentration unit and hydrogen purification are as first stage construction, form the system of preparing hydrogen from raw coke oven gas, and the desorption gas that is rich in methane this moment can directly be sent to the boiler burning and can not cause environmental pollution. During second-stage construction, a decarbonization unit and an LNG preparation unit are added on the basis of first-stage construction, so that the utility model can be constructed, and a crude gas hydrogen production and LNG co-production system can be utilized. And second phase construction in the system during do not influence the normal operating of first phase, consequently, through substep investment construction, reduced the risk of enterprise's investment, operation and operation from the angle of enterprise, thereby make the system can be accepted by the enterprise more easily, realize the industrialization operation of system.

(2) Compared with the prior art, raw coke oven gas hydrogen production coproduction LNG system accomplish the pressure boost that this system post treatment raw coke oven gas needs pressure basically through the mode (cubic compression pressure boost) of pressure boost in proper order before the deoxidation transform unit. The applicant takes raw gas as raw material and comprises the following components: o is₂：0.9mol％、N₂：42.3mol％、H₂：19.2mol％、CO：15.4mol％、CO₂：8.7mol％、CH₄：5.6mol％、CmHn：0.7mol％、H₂O: 7.2 mol%, a pressure of 4kPa, a temperature of 40 ℃ and a hydrogen production of 40000Nm³The hydrogen pressure of the product is 1.2MPa for example; will raw coke oven gas hydrogen manufacturing coproduction LNG in pressure boost mode and prior art in record several kinds of compression modes and contrast, its contrast result is as shown in the following table:

above-mentioned table is 89% according to the yield of hydrogen and calculates the tolerance that obtains each compression stage, tertiary compression mode that adopts among the hydrogen manufacturing coproduction LNG system all be minimum to shaft power and circulating water consumption when raw coke oven gas compresses. In addition, the third compression is arranged in front of the conversion device, and the temperature is increased because of conversion, so that a compressor after-cooler is not needed, the compression heat can be utilized, the consumption of circulating water is reduced, and more steam can be produced by the conversion device. From this, reduced and adopted the system obtain the cost of the higher hydrogen of economic value and LNG from the raw coke oven gas.

(3) Raw coke oven gas hydrogen manufacturing coproduction LNG system in, the utility model discloses still prepared LNG when hydrogen manufacturing for effective component in the raw coke oven gas has reduced the waste of the energy by abundant utilization. In addition, the utility model basically meets the pressure requirement of the system in the post-treatment of the raw coke oven gas before the deoxidation conversion unit, thereby reducing the energy consumption; in the utility model, the raw gas after decarburization is separated and purified by a two-stage vacuum-pumping pressure swing adsorption system, and the product hydrogen with the purity of 99.9% is finally obtained, and the recovery rate of the hydrogen in the raw gas can reach more than 89%; the practice of the applicant proves that when the raw gas has the same treatment capacity, the investment of equipment cost is reduced by adopting vacuum pumping pressure swing adsorption compared with the membrane separation in the prior art, so that the cost for preparing hydrogen and LNG from the raw gas is reduced.

Drawings

FIG. 1 is a schematic flow diagram of the system of the present invention;

1-decoking unit, 2-primary pressurizing and cooling liquid separation unit, 3-secondary pressurizing unit, 4-pretreatment unit, 5-tertiary pressurizing unit, 6-deoxidation conversion unit, 7-desulfurization unit, 8-decarburization unit, 9-methane concentration unit, 10-hydrogen purification unit, 11-LNG preparation unit, 12-blower, 13-first cooler, 14-first liquid separator, 15-screw compressor, 16-second cooler, 17-second liquid separator, 18-water washing unit, 19-TSA purification unit, 20-preheater, 21-purifying furnace, 22-humidifier, 23-two-stage conversion furnace, 24-wet desulfurization system, 25-dry desulfurization system and 26-absorption tower, 27-regeneration tower, 28-pressurization system, 29-drying device, 30-demercuration device and 31-cold box.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below with reference to the accompanying drawings. It is to be understood that the embodiments described are only some embodiments of the invention, and not all embodiments. Based on the embodiments in the present invention, all other embodiments obtained by a person skilled in the art without creative work belong to the protection scope of the present invention.

In the description of the present invention, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the drawings, and are only for convenience of description and simplification of description, but do not indicate or imply that the device or element referred to must have a specific orientation or be constructed and operated in a specific orientation, and thus, it should not be construed as limiting the present invention. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance.

In the description of the present invention, it should be noted that, unless explicitly stated or limited otherwise, the terms "mounted," "connected," "communicating," and the like are to be construed broadly, e.g., they may be fixedly connected, detachably connected, or integrally connected; of course, mechanical communication or electrical communication is also possible; in addition, the elements may be directly connected or indirectly connected through intervening elements, or the elements may be in communication with each other. The specific meaning of the above terms in the present invention can be understood according to specific situations by those skilled in the art.

Examples

1. The utility model discloses in pressure is the gauge pressure, LNG is for short for liquefied natural gas, and TSA is for short for the temperature swing adsorption system.

2. The raw material raw gas in the following examples consists of: o is₂：0.9mol％、N₂：42.3mol％、H₂：19.2mol％、CO：15.4mol％、CO₂：8.7mol％、CH₄：5.6mol％、CmHn：0.7mol％、H₂O: 7.2 mol%, wherein the impurity content is tar: 200mg/Nm³Crude benzene: 200mg/Nm³And naphthalene: 50mg/Nm³、H₂S：400mg/Nm³Organic sulfur: 300mg/Nm³、HCN：400mg/Nm³、NH₃：500mg/Nm³、Cl：50mg/Nm³(ii) a Pressure: 4kPa, temperature: 40 ℃; the hydrogen yield of the product is 40000Nm³The hydrogen pressure of the product is 1.2 MPa. According to the requirement of the hydrogen yield of the product, the raw gas requirement of the raw material is 140000Nm by reverse calculation³/h。

As shown in fig. 1, the utility model discloses a system of crude gas hydrogen manufacturing coproduction LNG, including decoking unit 1, a pressure boost cooling that communicate in proper order divide liquid unit 2, secondary pressure boost unit 3, preprocessing unit 4, cubic pressure boost unit 5, deoxidation transform unit 6, desulfurization unit 7, decarbonization unit 8, methane concentration unit 9, hydrogen purification unit 10, LNG preparation unit 11.

Specifically, as shown in fig. 1, an electrostatic decoking device is used in the decoking unit 1 for removing tar in raw gas. In the actual operation process, at least 1 electrostatic decoking device is adopted; specifically, the raw coke oven gas is subjected to tar removal in an electrostatic decoking device to obtain decoking raw coke oven gas. In addition, the decoking device in the embodiment can also be other devices or combination of devices with the same function, and the number of the electrostatic decoking devices can be adjusted according to the specific operation environment of the embodiment, so as to form the electrostatic decoking unit consisting of a plurality of electrostatic decoking devices.

As shown in fig. 1, the primary pressurizing and cooling liquid-separating unit 2 includes an air blower 12, a first cooler 13, and a first liquid separator 14, wherein the air blower 12, the first cooler 13, and the first liquid separator 14 are sequentially communicated. Specifically, the decoking raw gas is pressurized to 0.07MPa for the first time by the blower 12 and then enters the first cooler 13 for cooling, the cooled decoking raw gas enters the first liquid separator 14 for liquid separation, and the separated water is output out of the system, so that the molar content of water in the decoking raw gas is reduced to 4.4%, the energy consumption of subsequent compression is reduced, and the pressurized raw gas for the first time is obtained. In the actual operation process, the number of the blowers 12, the number of the first coolers 13 and the number of the first liquid distributors 14 are at least 1; in the embodiment, the blower is selected to pressurize the raw coke oven gas according to the characteristics of large gas volume and low compression ratio; in addition, the blower, the first cooler and the first liquid separator in this embodiment may be other devices or combinations of devices having the same function, and the number of the blower, the first cooler and the first liquid separator may be adjusted according to the specific operation environment of this embodiment.

As shown in fig. 1, the secondary pressurizing unit 3 includes a screw compressor 15. The secondary pressurizing unit 3 in this embodiment further includes a second cooler 16, a second liquid separator 17; wherein the screw compressor 15, the second cooler 16 and the second liquid separator 17 are communicated in sequence. Specifically, the secondary pressurization pressure is determined according to the pressure requirement of subsequent pretreatment and the reasonable size of the equipment pipeline, in the implementation, the primary pressurized raw gas is pressurized to 0.6MPa through a screw compressor 15, then the pressurized primary pressurized raw gas is input into a second cooler 16 for cooling, the cooled primary pressurized raw gas enters a second liquid separator 17 for liquid separation, the separated water is output out of the system, and finally the secondary pressurized raw gas is obtained. According to the characteristics of large air volume, high compression ratio and dirty and oil-containing raw gas, the screw compressor is selected to pressurize the raw gas. In addition, in the actual operation process, the number of the screw compressors 15, the second coolers 16 and the second liquid separators 17 is at least 1; in addition, the screw compressor, the second cooler and the second liquid separator in this embodiment may be other devices or combinations of devices having the same function, and the number of the screw compressor, the second cooler and the second liquid separator may be adjusted according to the specific operating environment of this embodiment.

As shown in fig. 1, the pretreatment unit 4 includes a water washing unit 18 and a TSA purification unit 19, which are connected in series. Wherein the water washing unit 18 is a water washing tower, the secondary pressurized raw coke oven gas enters the water washing tower and is subjected to two-stage water washing in the water washing tower to remove NH in the raw coke oven gas₃The content of (A) is reduced to be below 100ppm, thereby obtaining the deamination raw coke oven gas. In the actual operation process, in order to control NH in the raw gas₃The content of (A) is less than 100ppm, the number of the water washing towers can be adjusted according to actual conditions, and a water washing unit consisting of a plurality of water washing towers is formed.

The TSA purification unit 19 comprises at least 2 temperature swing adsorption towers, deamination raw gas enters the temperature swing adsorption towers, tar, benzene and naphthalene in the deamination raw gas are further removed by the temperature swing adsorption towers, and purified raw gas is obtainedGas, wherein NH in raw gas is purified₃The content is less than or equal to 100ppm, and the tar content is less than or equal to 1mg/Nm³The benzene content is less than or equal to 10mg/Nm³Naphthalene content of less than or equal to 1mg/Nm³. In the actual operation process, the number of the temperature swing adsorption towers in this embodiment can be adjusted according to the amount of the raw coke oven gas processed by the system in this embodiment, and the system may be a TSA system composed of a plurality of (more than 2) temperature swing adsorption towers.

As shown in fig. 1, the tertiary pressurizing unit 5 is a centrifugal compressor. Wherein, purify the raw coke oven gas and carry out the pressure boost according to the specific application environment in the product hydrogen later stage that this system prepared in centrifugal compressor, in this embodiment, purify the raw coke oven gas and enter into centrifugal compressor and carry out the pressure boost to 1.6 MPa. In this embodiment, the purified raw gas obtained through the preliminary treatment is relatively clean, and therefore, the centrifugal compressor is selected to pressurize the purified raw gas. In the actual operation process, at least 1 centrifugal compressor is used; in addition, the centrifugal compressor in the embodiment may also be other devices or combination of devices with the same function, and the number of the centrifugal compressors may be adjusted according to the specific operation environment of the embodiment, so as to form a triple pressurizing unit composed of a plurality of centrifugal compressors.

As shown in fig. 1, the deoxidation conversion unit 6 includes a preheater 20, a purification furnace 21, a humidifier 22, and a two-stage conversion furnace 23, wherein the preheater 20, the purification furnace 21, the humidifier 22, and the two-stage conversion furnace 23 are connected in sequence. Further, the purified raw gas pressurized by the centrifugal compressor enters a preheater 20 and is heated to 180 ℃; the heated purified raw gas enters a purification furnace 21 to remove toxic substances and oxygen in the raw gas, and the temperature of the raw gas treated by the purification furnace 21 is-350 ℃; then the humidifier 22 is used for spraying water to the raw gas from the purification furnace to cool, and the high temperature of the raw gas is utilized to convert the water into steam, so that the water-gas ratio in the raw gas is improved; the cooled raw coal gas and water vapor enter a two-stage shift converter 23 to promote the conversion of CO and water vapor into H under the action of a catalyst₂And CO, wherein the cooled raw coal gas and the water vapor firstly enter a first section of the two-section shift converter 23 for shift reaction and are subjected to first-section shift reactionThe content of CO in the raw coke oven gas is 4 percent; then the raw gas after the first-stage shift reaction is cooled to 200 ℃ and then sent into the second stage of the two-stage shift converter 23 for shift reaction, and the shifted raw gas with the CO content less than or equal to 1 percent is obtained after the second-stage shift reaction. The obtained transformed raw gas is sent to the next processing unit after being cooled to 40 ℃. In the actual process, the raw gas purified by the first-stage conversion can be preheated before the conversion and cooled to 200 ℃ by the byproduct steam of the waste heat boiler. The catalyst used in this example is a commercially available catalyst for CO shift.

As shown in fig. 1, the desulfurization unit 7 includes a wet desulfurization system 24 and a dry desulfurization system 25; wherein, the wet desulphurization system 24 is communicated with the dry desulphurization system 25. Further, the transformed raw gas obtained by the two-stage transforming furnace 23 enters the wet desulphurization system 24, and more than 97% of H in the transformed raw gas₂S is removed, the transformed raw gas after wet desulphurization enters a dry desulphurization system 25 to further remove H in the raw gas₂S is removed, and H is finally obtained₂S is less than or equal to 1mg/Nm³The desulfurized raw gas. The sulfur removed in the wet desulfurization system 24 is made into sulfur for recovery. In the embodiment, the wet desulfurization system adopts a PDS-600 desulfurization method using soda ash as an alkali source. The dry desulfurization system 25 comprises 2 dry desulfurization towers, and the filler in the dry desulfurization tower is a zinc oxide desulfurizer.

As shown in fig. 1, the decarburization unit 8 includes an absorption tower 26 and a regeneration tower 27; wherein the absorption column 26 communicates with the regeneration column 27. Further, the desulfurized raw gas enters the absorption tower 26 to remove CO in the desulfurized raw gas₂Removing to obtain CO₂The decarbonized raw gas with the content less than or equal to 30 ppm; adsorption of CO in the absorption column 26₂The absorption liquid enters a regeneration tower 27 for regeneration, and the regenerated absorption liquid is reused in the absorption tower for absorbing CO in the desulfurized raw coke oven gas₂. The absorption liquid in the absorption tower in this embodiment is MDEA (methyldiethanolamine), and in the actual operation process, other absorption liquids having the same function may also be selected; in addition, the embodiment can also have other same functionsOr a combination of devices.

As shown in fig. 1, the methane concentration unit 9 is a vacuum pressure swing adsorption system I, and the vacuum pressure swing adsorption system I includes a pressure swing adsorption tower, a vacuum pump, a pipeline, a valve, and other devices. In the actual operation process, the pressure swing adsorption tower and the vacuum pump are both multiple, and the number of the pressure swing adsorption tower and the number of the vacuum pump can be adjusted to be multiple according to the specific operation environment of the embodiment. Specifically, CO removal by MDEA₂And then the obtained decarbonized raw gas enters a pressure swing adsorption tower, methane in the decarbonized raw gas is adsorbed by an adsorbent in the pressure swing adsorption tower, unadsorbed decarbonized raw gas is output from the pressure swing adsorption tower to obtain a crude product hydrogen, and the methane adsorbed by the adsorbent is desorbed and then enters an LNG preparation unit.

As shown in fig. 1, the hydrogen purification unit 10 is a vacuum pressure swing adsorption system II, wherein the vacuum pressure swing adsorption system II includes a pressure swing adsorption tower, a vacuum pump, a pipeline, a valve, and other devices. In the actual operation process, the pressure swing adsorption tower and the vacuum pump are both multiple, and the number of the pressure swing adsorption tower and the number of the vacuum pump can be adjusted to be multiple according to the specific operation environment of the embodiment. Specifically, the obtained crude product hydrogen enters a pressure swing adsorption tower, and the pressure swing adsorption tower further separates and purifies the crude product hydrogen, so that the product gas with the purity of 99.9% is obtained.

Wherein, the adsorption towers in the vacuum pressure swing adsorption system I and the vacuum pressure swing adsorption system II are sequentially subjected to the following steps in a cycle process:

adsorption process

Raw gas enters the adsorption tower in an adsorption state from the tower bottom of the adsorption tower, and N in the raw gas is adsorbed by a plurality of adsorbents in a sequentially selective manner₂And CO and other impurities are adsorbed, and unadsorbed hydrogen in the raw coke oven gas flows out from the top of the tower as product gas and is sent out after being stabilized by a pressure regulating system.

When the front edge of the mass transfer zone (called adsorption front edge) of the adsorbed impurities reaches the reserved section of the bed layer outlet, the feed gas inlet valve and the product gas outlet valve of the adsorption tower are closed, the adsorption is stopped, and the adsorption bed starts to shift to the regeneration process.

Pressure equalizing and reducing process

After the adsorption process is finished, the hydrogen with higher pressure in the tower is put into other lower-pressure adsorption towers which have finished regeneration along the adsorption direction, the process is not only a pressure reduction process, but also a process of recovering the hydrogen in the dead space of the bed layer, and in order to ensure that the hydrogen is fully recovered, continuous pressure equalization and pressure reduction are carried out for many times.

Reverse discharge process

After the pressure equalization process is finished, the adsorption front reaches the bed outlet. At this time, the pressure of the adsorption column was decreased to 0.03MPa against the adsorption direction, at which time the adsorbed impurities began to be desorbed largely from the adsorbent.

Vacuum pumping process

After the reverse discharging process is completed, in order to completely regenerate the adsorbent, the adsorption bed is evacuated by a vacuum pump in the reverse direction to completely desorb the impurities in the adsorbent.

Voltage equalizing and boosting process

After the vacuumizing regeneration process is completed, the adsorption tower is sequentially pressurized by using higher-pressure hydrogen from other adsorption towers, the process corresponds to a pressure equalizing and reducing process, not only is the pressure increasing process, but also the process of recovering the bed dead space hydrogen of other towers, and the pressure equalizing and increasing process needs to be continuously carried out for multiple times.

Product gas pressure boosting process

After the pressure equalizing and boosting process is completed for many times, in order to stably switch the adsorption tower to the next adsorption and ensure that the product purity does not fluctuate in the process, the pressure of the adsorption tower needs to be slowly and stably increased to the adsorption pressure by the overhead gas through the pressure boosting regulating valve.

After the adsorption tower passes through the process, the adsorption tower completes a complete adsorption-regeneration cycle and is ready for the next adsorption.

As shown in fig. 1. The illustrated LNG production unit 11 includes a pressurization system 28, a drying system 29, a demercuration device 30, and a cold box 31; wherein, the pressurization system 28, the drying system 29, the demercuration device 30 and the cold box 31 are communicated in sequence. Specifically, methane desorbed from a pressure swing adsorption tower in the vacuum-pumping pressure swing adsorption system I firstly enters a pressurization system, then sequentially passes through a drying system and a demercuration device and then enters a cold box, and finally LNG is obtained.

In the actual construction process of the system, the decarbonization unit and the LNG preparation unit can be separately constructed with the first-stage construction unit comprising the decoking unit, the first-stage pressurizing and cooling liquid separation unit, the second-stage pressurizing unit, the pretreatment unit, the third-stage pressurizing unit, the deoxidation conversion unit, the desulfurization unit, the methane concentration unit and the hydrogen purification unit, so that the operation cost of an enterprise is reduced.

Finally, it should be noted that: the above embodiments are only preferred embodiments of the present invention to illustrate the technical solution of the present invention, but not to limit the same, and certainly not to limit the scope of the present invention; although the present invention has been described in detail with reference to the foregoing embodiments, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention; the modifications or the substitutions do not make the essence of the corresponding technical solutions depart from the scope of the technical solutions of the embodiments of the present invention; that is, the technical problems solved by the present invention are still consistent with the present invention, and all the modifications or colors made in the spirit and the idea of the main design of the present invention are included in the protection scope of the present invention; in addition, will the technical scheme of the utility model direct or indirect application is in other relevant technical field, all including on the same reason the utility model discloses an in the patent protection scope.

Claims

1. The system for producing hydrogen and coproducing LNG from raw gas is characterized by comprising a decoking unit (1), a primary pressurizing and cooling liquid separating unit (2), a secondary pressurizing unit (3), a pretreatment unit (4), a tertiary pressurizing unit (5), a deoxidation conversion unit (6), a desulfurization unit (7), a decarburization unit (8), a methane concentration unit (9), a hydrogen purification unit (10) and an LNG preparation unit (11) which are sequentially communicated;

the decarbonization unit: for removing CO in desulfurized raw gas₂Finally, obtaining decarbonized raw gas;

2. The crude gas hydrogen-production and LNG co-production system according to claim 1, wherein the decoking unit (1) is an electrostatic decoking device.

3. The crude gas hydrogen-production and LNG-coproduction system as defined in claim 1, wherein the primary pressurizing and cooling liquid-separating unit (2) comprises a blower (12) for pressurizing the decoking crude gas, a first cooler (13) communicated with the blower (12) for cooling the pressurized decoking crude gas, and a first liquid separator (14) communicated with the first cooler (13) for separating the cooled decoking crude gas and obtaining the primary pressurizing crude gas;

the secondary pressurization unit (3) comprises a screw compressor (15) which is communicated with the first liquid separator (14) and is used for pressurizing the primary pressurized raw coke oven gas.

4. The raw gas hydrogen-production and LNG cogeneration system according to claim 1, characterized in that the pretreatment unit (4) comprises a water washing unit (18) and a TSA purification unit (19) which are sequentially communicated; the washing unit (18) comprises a washing tower for washing the secondary supercharged raw gas after supercharging and obtaining deamination raw gas, and the TSA purification unit (19) comprises a temperature swing adsorption tower for further removing tar, benzene and naphthalene in the deamination raw gas to obtain purified raw gas; wherein, the temperature swing adsorption tower is at least 2.

5. The system for cogeneration of crude gas hydrogen and LNG as claimed in claim 4, wherein the tertiary pressurization unit (5) is a centrifugal compressor communicating with the TSA purification unit (19) and configured to pressurize the purified crude gas.

6. The system for cogeneration of raw gas and LNG as claimed in claim 1, wherein the deoxygenation conversion unit (6) comprises a preheater (20) for preheating the pressurized purified raw gas, a purification furnace (21) communicating with the preheater (20) for removing toxic substances and oxygen from the purified raw gas, a humidifier (22) communicating with the purification furnace (21) for increasing a water-to-gas ratio of the purified raw gas while reducing the temperature of the purified raw gas by spraying water, and a humidifier (22) communicating with the humidifier (22) for promoting CO and waterConversion of steam to H₂And CO₂The two-stage shift converter (23).

7. The system for cogeneration of crude gas hydrogen production and LNG as claimed in claim 1, wherein the desulfurization unit (7) comprises a unit for converting H in crude gas₂A wet desulphurization system (24) for S removal, which is communicated with the wet desulphurization system (24) and is used for further transforming H in the raw coke oven gas₂A dry desulfurization system (25) for S removal.

8. The system for the cogeneration of crude gas hydrogen and LNG as claimed in claim 1, wherein the decarbonization unit (8) comprises a device for removing CO from desulfurized crude gas₂And an absorption tower (26) for obtaining decarbonized raw gas, which is communicated with the absorption tower (26) and is used for absorbing CO₂A regeneration tower (27) for regenerating the absorption liquid.

9. The system for producing hydrogen and LNG from raw gas as claimed in claim 1, wherein the methane concentration unit (9) is a vacuum-pumping pressure swing adsorption system I for adsorbing methane in the decarbonized raw gas and obtaining a crude product hydrogen; wherein, the crude product hydrogen from the vacuumizing pressure swing adsorption system I enters a hydrogen purification unit, and the adsorbed methane enters an LNG preparation unit after being desorbed.

10. The system for producing hydrogen and LNG from raw coke oven gas as claimed in claim 9, wherein the hydrogen purification unit (10) is a vacuum-pumping pressure swing adsorption system II for further separating and purifying the crude product hydrogen.

11. The raw gas hydrogen-production and LNG cogeneration system according to claim 9 or 10, wherein the LNG production unit (11) comprises a pressurization system (28), a drying device (29), a demercuration device (30) and a cold box (31) which are sequentially communicated; and the methane is desorbed and then sequentially passes through a pressurizing system, a drying device, a demercuration device and a cold box to be prepared into LNG.