WO2022180740A1

WO2022180740A1 - Carbon dioxide gas recovery type hydrogen production system utilizing lng

Info

Publication number: WO2022180740A1
Application number: PCT/JP2021/007085
Authority: WO
Inventors: 信三伊藤
Original assignee: 株式会社ユーリカエンジニアリング
Priority date: 2021-02-25
Filing date: 2021-02-25
Publication date: 2022-09-01
Also published as: JP6951613B1; JPWO2022180740A1

Abstract

In the present invention, water vapor and natural gas, which is produced by vaporizing LNG, are subjected to a water vapor reforming reaction and a shift reaction in the presence of a catalyst, and such reactant becomes a mixed gas that includes hydrogen and carbon dioxide gas. The mixed gas is separated by a hydrogen separation device into hydrogen gas and an off gas, and the hydrogen gas is fed to a hydrogen-using device. The off gas is sent to a combustion furnace as fuel for the heating required for water vapor reforming and is subjected, with oxygen supplied from an oxygen supply device, to a combustion reaction. A combustion exhaust gas that includes carbon dioxide gas and water vapor, after being pre-cooled by a combustion exhaust gas pre-cooling device, is subjected to heat exchange of LNG cold energy with LNG in an LNG vaporization device, the LNG is vaporized into natural gas, the combustion exhaust gas is cooled, the water vapor is condensed and the water content thereof is discharged, resulting in a low-temperature recovered carbon dioxide gas. Due to this configuration, all of the carbon dioxide gas generated during hydrogen production is collected in the combustion exhaust gas arising from combustion of fuel in the combustion furnace of a water vapor reforming device, and the carbon dioxide gas is brought to a low temperature and collected, thus making it possible to reduce liquefaction power for the carbon dioxide gas.

Description

Carbon dioxide recovery type hydrogen production system using LNG

The present invention relates to a hydrogen production system, and more particularly to a hydrogen production system that utilizes LNG and can efficiently recover carbon dioxide gas.

The problem of global warming is becoming more and more serious, and COP24 adopted an implementation policy to operate a framework for global warming countermeasures, and an international framework in which almost all countries that emit greenhouse gases participate has begun to move. . The greatest target for global warming countermeasures is fossil fuel-derived thermal power generation, but society's interest in the power source of automobiles is increasing from the viewpoint of global warming and environmental pollution of exhaust gas, and fossil fuel-derived internal combustion locomotives are being developed. There is a movement to ban its manufacture and sale in the future.
Therefore, storage batteries, hydrogen, and CCUS are attracting attention as global warming countermeasure technologies. CCUS is the reuse or underground storage of carbon dioxide generated when fossil fuels are used.
In addition, a fuel shift from coal and oil, which have high carbon dioxide (CO ₂ ) emission factors, to natural gas, which has low emission factors, has begun, and many liquefied natural gas (LNG) satellite stations are being built. Although LNG cold energy, which is generated in large quantities at LNG satellite terminals, is extremely useful, its effective utilization is hardly performed, and it is vaporized with seawater or hot water and discarded.
Patent Document 1 discloses a reforming unit 1 that steam-reforms a raw material gas to reform it into a reformed gas containing hydrogen and carbon dioxide, and separates the obtained reformed gas into hydrogen gas and off-gas. A hydrogen separation unit 2 that sends out hydrogen gas, a carbon dioxide recovery unit 3 that separates and recovers carbon dioxide gas from off-gas, and a combustion device 12b that is provided in the reforming unit 1 from the recovery unit 3 to recover the off-gas from which the carbon dioxide gas is recovered. is provided with an off-gas supply line L4 for feeding the off-gas as fuel gas to the combustion device 12b together with the fuel gas.

JP 2014-47085 A

In the hydrogen production apparatus described in Patent Document 1, the carbon dioxide contained in the off-gas obtained by separating the hydrogen from the reformed gas sent from the reforming section 1 is recovered. However, the carbon dioxide gas is not recovered from the combustion exhaust gas discharged from the combustion device 12b of the reformer 1, and the measures against global warming are insufficient.

The object of the present invention is to combine all carbon dioxide gas generated in hydrogen production into flue gas generated by fuel combustion for generating the heat required for steam reforming of natural gas and steam, and precool the flue gas. By exchanging LNG cold heat with LNG in the LNG vaporizer, LNG is vaporized into natural gas, and all the carbon dioxide generated in hydrogen production is recovered at a low temperature, reducing the liquefaction power of carbon dioxide. It is an object of the present invention to provide a carbon dioxide gas recovery type hydrogen production system that utilizes LNG and is effective in preventing global warming.

The present invention includes a natural gas supply device that vaporizes LNG supplied from the LNG supply device into natural gas and supplies it, and a combustion reaction between fuel and oxygen supplied from the oxygen supply device in a combustion furnace, and reforming with combustion heat. a steam reformer for generating a reformed gas by heating a vessel and causing a steam reforming reaction between the natural gas and steam supplied to the reformer in the presence of a reforming catalyst; a reformed gas cooling device that is connected and cools the supplied reformed gas; and a carbon monoxide gas that is supplied with the reformed gas cooled from the reformed gas cooling device and contained in the reformed gas. a shift reactor for generating a mixed gas containing hydrogen gas and carbon dioxide by causing a shift reaction with water vapor in the presence of a CO conversion catalyst; and a mixed gas cooling device connected to the shift reactor for cooling the supplied mixed gas. a device, a hydrogen separation device for separating hydrogen gas from the mixed gas supplied by being connected to the mixed gas cooling device, delivering the separated hydrogen gas, and delivering off-gas, the hydrogen separation device and the a fuel supply circuit connected to a combustion furnace and supplying the off-gas as the fuel to the combustion furnace; and a flue gas generated by combustion of the fuel is supplied from the combustion furnace to pre-cool the flue gas to produce carbon dioxide gas. and a flue gas precooling device for precooling flue gas containing saturated steam and a flue gas precooling device provided in the natural gas supply device, the LNG is supplied from the LNG feeder, and the precooled flue gas is supplied from the flue gas precooling device, The LNG cold generated when the LNG is vaporized is heat-exchanged with the pre-cooled flue gas to vaporize the LNG into natural gas and cool the pre-cooled flue gas to condense the saturated water vapor. A carbon dioxide gas recovery system utilizing LNG, provided with an LNG vaporizer for cooling to a low temperature and discharging the recovered carbon dioxide gas, and a carbon dioxide gas delivery device for delivering the recovered carbon dioxide gas discharged from the LNG vaporizer. It is a hydrogen production system.

The carbon dioxide recovery type hydrogen production system utilizing LNG of the present invention heats natural gas obtained by vaporizing LNG and steam in the presence of a reforming catalyst to steam reform, and shift reaction of the reformed gas with steam. A mixed gas containing hydrogen and carbon dioxide is produced by the hydrogen separator, and the mixed gas is separated into hydrogen gas and off-gas by a hydrogen separator, and the hydrogen gas is sent out. The off-gas, along with natural gas, is sent as fuel to the combustion furnace of the steam reformer and undergoes a combustion reaction with oxygen for the heating required for steam reforming. The flue gas is precooled in the flue gas cooling device and then cooled to a low temperature by exchanging LNG cold heat with LNG in the LNG vaporizer.
As a result, all the carbon dioxide generated in the hydrogen production, that is, the carbon dioxide contained in the off-gas and the carbon dioxide generated by the combustion of the hydrogen contained in the off-gas and the natural gas are combined into the flue gas discharged from the combustion furnace. can be done. By pre-cooling this flue gas and exchanging the cold heat of LNG with LNG in an LNG vaporizer, LNG is vaporized into natural gas, and all the carbon dioxide generated in hydrogen production is recovered at a low temperature. can be done. Furthermore, since the hydrogen gas and natural gas contained in the off-gas are subjected to a combustion reaction with oxygen in the combustion furnace, the components of the discharged flue gas are carbon dioxide and water vapor only, facilitating the recovery of carbon dioxide.

1 is a block diagram showing the overall configuration of a carbon dioxide recovery type hydrogen production system utilizing LNG according to a first embodiment; FIG. It is a figure which shows the structure of the LNG vaporization apparatus of 1st Embodiment. FIG. 2 is a block diagram showing the overall configuration of a carbon dioxide recovery type hydrogen production system utilizing LNG according to a second embodiment;

1. Configuration of the First Embodiment A carbon dioxide gas recovery type hydrogen production system 1a utilizing LNG according to the first embodiment, as shown in FIG. , a steam reforming device 20, an oxygen supply device 24, a reformed gas cooling device 25, a shift reaction device 30, a mixed gas cooling device 35, a hydrogen separation device 40, a fuel supply circuit 50, and a combustion exhaust gas. A cooling device 60 , a carbon dioxide delivery device 65 and a carbon dioxide liquefaction device 66 are provided.

The natural gas supply device 10 includes a LNG tank that stores LNG (liquefied natural gas) transported from a port by an LNG tank truck, and an LNG vaporizer 12 that vaporizes the liquefied natural gas supplied from the LNG tank to produce natural gas. Prepare. The LNG tank constitutes an LNG feeder 11 that feeds LNG to an LNG vaporizer 12 . The natural gas supply device 10 vaporizes the LNG supplied from the LNG supply device 11 into natural gas in the LNG vaporizer 12 and supplies the natural gas to the steam reformer 20 through the pipeline 19 .

The steam reformer 20 includes a reformer 21 filled with a reforming catalyst, a water supply device 22 that supplies water to the reformer 21, and a combustion furnace 23 that heats the reformer 21 by burning fuel. Prepare. The reformer 21 is supplied with natural gas as a raw material from the natural gas supply device 10 through the pipeline 19 and is supplied with water or steam from the water supply device 22 . The combustion furnace 23 is supplied with natural gas as fuel from the natural gas supply device 10 through a pipeline 19 and a pipeline 51 branched from the pipeline 19, and offgas from the hydrogen separator 40 through a pipeline 52 as fuel. supplied. Oxygen is supplied from an oxygen supply device 24 to the combustion furnace 23 through a pipeline 26 , and the fuel and oxygen undergo a combustion reaction to generate combustion heat and heat the reformer 21 .

As a result, the water supplied to the reformer 21 becomes high-temperature steam, and methane gas contained in natural gas, for example, becomes steam as shown in chemical formulas (1) and (2) in the presence of high-temperature steam and a reforming catalyst. A reforming reaction results in a reformed gas containing hydrogen, carbon dioxide and carbon monoxide.
CH ₄ +2H ₂ O→4H ₂ +CO ₂ (endothermic) (1)
CH ₄ +H ₂ O→3H ₂ +CO (endothermic) (2)
The steam reforming reaction is an endothermic reaction as a whole, and the heat of reaction is supplied from the combustion heat generated in the combustion furnace 23 .

A reformed gas cooling device 25 is connected to the steam reforming device 20 . The reformed gas cooling device 25 is a known cooling device, in which the reformed gas passes through the high temperature side of the heat exchanger and the heat medium passes through the low temperature side of the heat exchanger. The temperature of the gas drops and the temperature of the heat transfer medium rises. The heat medium circulates between the low-temperature side of the heat exchanger and a radiator such as a radiator, and the heat is dissipated by the radiator to lower the temperature. The reformed gas cooler 25 cools the hot reformed gas sent from the steam reformer 20 to a temperature suitable for the CO shift reaction in the CO shift reactor 30 .

The CO shift reactor 30 is supplied with the reformed gas cooled from the reformed gas cooling device 25, and the carbon monoxide gas and water vapor contained in the reformed gas are represented by the chemical formula (3) in the presence of the CO conversion catalyst. , the reformed gas is transformed into a mixed gas containing hydrogen gas and carbon dioxide gas.
CO ₊ _H2O →H2+ _CO2 (exothermic) (3)

A mixed gas cooling device 35 is connected to the CO shift reactor 30 . The mixed gas cooling device 35 is a known cooling device, and is configured such that a heat medium passes through a heat exchange coil and a mixed gas passes through a cooling chamber housing the heat exchange coil, and the mixed gas exchanges heat with the heat medium. is cooled to below the dew temperature and dehumidified. The heat medium whose temperature rises by cooling the mixed gas is cooled by circulating, for example, a condensing unit. The dehumidified mixed gas is supplied to a hydrogen separator (PSA) 40 .

For the hydrogen separator 40, for example, a known pressure swing adsorption (PSA) type hydrogen separator is used. A PSA type hydrogen separator has at least three adsorption towers, and each adsorption tower is filled with a combination of zeolitic adsorbent, activated carbon, silica gel, etc., as an adsorbent. The hydrogen separation device 40 is provided with a pressure equalizing control valve on the hydrogen gas outflow side of each adsorption tower and a three-way switching valve on the offgas outflow side, and the switching of the flow direction is controlled by each three-way switching valve and the pressure equalizing control valve. , each adsorption tower repeats a series of treatment steps consisting of adsorption, equalizing pressure discharge, pressure reduction, washing, pressure equalization pressure injection, and pressure increase so as to perform a process that is shifted by one step from the adjacent adsorption tower, and the mixed gas is hydrogen gas and offgas and separate continuously. Hydrogen gas separated from the mixed gas is sent to the hydrogen utilization device 45 . In the hydrogen utilization device 45, hydrogen gas is utilized for power generation, iron manufacturing, ammonia production, smart cities, and the like. The off-gas includes carbon dioxide contained in the mixed gas, hydrogen gas that could not be separated by the hydrogen separator 40, hydrogen gas for purging, and unreformed methane gas. It is delivered to the combustion furnace 23 of the quality device 20 .

The fuel supply circuit 50 has pipelines 19 and 51 connecting the natural gas supply device 10 and the combustion furnace 23, and a pipeline 52 connecting the hydrogen separator 40 and the combustion furnace 23. The pipeline 52 is connected to the hydrogen separator. An off-gas holder 53 is provided between the hydrogen separator 40 and the combustion furnace 23 to reduce the pulsation of the off-gas delivered from the hydrogen separator 40 . As a result, the natural gas and the off-gas undergo a combustion reaction with oxygen supplied from the oxygen supply device in the combustion furnace 23 as shown in chemical formulas (4) and (5) to generate combustion heat and heat the reformer 21. and generate hot flue gas.
CH ₄ +2O ₂ →CO ₂ +2H ₂ O (methane gas, main component of natural gas) (4)
2H ₂ +O ₂ +nCO ₂ →2H ₂ O+nCO ₂ (off gas) (5)

The high-temperature flue gas (mixed gas of carbon dioxide gas and water vapor) discharged from the combustion furnace 23 is heat-exchanged with LNG in the LNG vaporizer 12 provided in the natural gas supply device 10, and the LNG is vaporized into natural gas. However, the high-temperature flue gas has a much larger amount of heat (sensible heat and latent heat) than the amount of heat required to vaporize LNG, and contains a large amount of water vapor. Therefore, in order to cool the carbon dioxide contained in the flue gas to the low temperature T1 in the LNG vaporizer 12 and vaporize the LNG into natural gas at the desired temperature T2, the flue gas is supplied to the LNG vaporizer 12. It must be precooled and dehumidified to a precooling temperature T3 corresponding to the temperatures T1 and T2.

Therefore, the flue gas discharged from the combustion furnace 23 is supplied to the flue gas precooling device 60 to be precooled and dehumidified. The flue gas precooling device 60 is a known cooling device, and cools the flue gas to a precooling temperature T3 below the dew point temperature while the cooling water passes through the heat exchange coils and the flue gas passes through the cooling chamber housing the heat exchange coils. After cooling, the water vapor contained in the flue gas is condensed, and the flue gas becomes pre-cooled flue gas containing carbon dioxide gas and saturated water vapor. The cooling water heat-transferred from the flue gas is cooled by circulating, for example, a cooling tower. The pre-cooled flue gas is supplied to the LNG vaporizer 12 and the condensed water is reused or discharged.

The LNG vaporizer 12 includes a vaporizer 15 that vaporizes the LNG supplied from the LNG supply device 11 into natural gas and sends it to the steam reformer 20, and a precooled flue gas precooled to a temperature T3 in the flue gas precooler 60. is converted into dry carbon dioxide containing almost no saturated water vapor, and then converted into recovered carbon dioxide and discharged. That is, the exhaust gas cooling device 70 cools the pre-cooled combustion exhaust gas to near the freezing temperature of water to condense the saturated water vapor into dry carbon dioxide, and then cools it to a low temperature T1 suitable for producing liquefied carbon dioxide to recover carbon dioxide. turn to gas. The vaporizer 15 has a low temperature side 15b where LNG is vaporized into natural gas while flowing, and a high temperature side 15a where the non-freezing heat medium heated by the exhaust gas cooling device 70 flows. The antifreeze heat medium flowing on the high temperature side 15a receives LNG cold heat transferred from the LNG flowing on the low temperature side 15b.

The exhaust gas cooling device 70 has a housing 74 formed with a gas passage 74c through which pre-cooled combustion exhaust gas flows in from an inlet 74a, becomes recovered carbon dioxide gas, and flows out from an outlet 74b. 72 and second cooling coils 73 are sequentially housed in series from one side (inflow port 74a side) toward the other side (outflow port 74b side). The first cooling coil 71 is provided with an outlet for the antifreezing heat medium on one side of the gas passage 74c and an inlet on the other side. The second cooling coil 73 has an outlet for the non-freezing heat medium on one side of the gas passage 74c and an inlet on the other side. A drain pan 75 is formed on the bottom surface of the gas passage 74c so as to face the lower surfaces of the first cooling coil 71 and the eliminator 72 . A drain port 75a is provided on the bottom surface of the drain pan 75 . As the pre-cooled combustion exhaust gas is lowered to the vicinity of the freezing temperature of water by the first cooling coil 71 , most of the saturated steam is condensed and dropped, and condensed water and water droplets of the condensed water captured by the eliminator 72 are collected on the drain pan 75 . , flows out through the water seal 79 from the water flow port 75a and is reused or discharged. The drain pan 75, the water flow port 75a, and the water seal 79 collect the condensed water captured by the first cooling coil 71 and the eliminator 72 from the saturated water vapor contained in the precooled combustion exhaust gas, and the condensed water flows out of the gas passage 74c. Construct an outflow part.

The exhaust gas cooling device 70 includes a first heat medium circulation circuit 76, a second heat medium circulation circuit 77, a non-freezing heat medium circulating through the first heat medium circulation circuit 76, and a non-freezing heat medium circulating through the second heat medium circulation circuit 77. A heat exchanger 78 is provided to exchange heat with the freezing medium. In the first heat medium circulation circuit 76, the non-freezing heat medium is circulated through the first cooling coil 71 and the high temperature side 78a of the heat exchanger 78 by a pump (not shown). In the second heat medium circulation circuit 77, the antifreeze heat medium is circulated through the second cooling coil 73, the low temperature side 78b of the heat exchanger 78, and the high temperature side 15a of the vaporizer 15 by a pump (not shown).

The recovered carbon dioxide at the low temperature T1 that has flowed out of the exhaust gas cooling device 70 of the LNG vaporizer 12 is delivered to the carbon dioxide delivery device 65 . The carbon dioxide gas delivery device 65 is composed of a pipe line 64 and a carbon dioxide gas liquefaction device 66, liquefies the recovered carbon dioxide gas into liquefied carbon dioxide gas, and supplies the carbon dioxide gas to the carbon dioxide utilization device 67 with high transportation efficiency. In the carbon dioxide utilization device 67, the recovered carbon dioxide is used for hydrocarbon production, biofuel, greenhouse cultivation, civil engineering materials, carbon dioxide recovery and storage (CCS), enhanced oil development (EOR), and the like.
In the first embodiment, since the low-temperature recovered carbon dioxide gas is liquefied by the carbon dioxide gas liquefaction device 66, the liquefied carbon dioxide gas can be supplied to the carbon dioxide utilization device 67 at low cost and with high transportation efficiency by a tank truck, tanker, or the like. . However, the carbon dioxide liquefaction device 66 may not be provided in the carbon dioxide gas delivery device 65, and the recovered carbon dioxide cooled to a low temperature by the LNG vaporization device 12 may be supplied to the carbon dioxide utilization device 67 without being liquefied.
In addition, natural gas is supplied as fuel to the combustion furnace 23 of the steam reforming device 20, but if the off-gas sent from the hydrogen separation device 40 contains a large amount of combustible substances such as hydrogen, the natural gas is used in the combustion furnace. 23 need not be supplied.

2. Operation and Effect of First Embodiment In the LNG vaporizer 12, the low temperature side 15b of the vaporizer 15 is supplied with LNG from the LNG supply device 11, and the high temperature side 15a is supplied with the antifreeze circulating through the second heat medium circulation circuit 77. A heat carrier is supplied. As a result, the LNG and the antifreezing heat medium exchange heat with the LNG cold heat in the vaporizer 15, the LNG is vaporized into natural gas and sent to the steam reformer 20, and the LNG cold heat is transferred to the antifreezing heat medium. It is cooled to a temperature lower than the low temperature T1 of the recovered carbon dioxide gas and returned to the second cooling coil 73 . While flowing through the second cooling coil 73, the cooled antifreeze heat medium cools the dry carbon dioxide gas flowing through the gas passage 74c to the low temperature T1, thereby raising the temperature. The antifreezing heat medium whose temperature has risen flows through the second heat medium circulation circuit 77, the low temperature side 78b of the heat exchanger 78, the first heat medium circulation circuit 76, and the high temperature side 78a of the heat exchanger 78. It exchanges heat with the flowing antifreeze heat medium. As a result, the non-freezing heat medium circulating in the second heat medium circulation circuit 77 is heated to a temperature equal to or higher than the freezing temperature of water and supplied to the high temperature side 15 a of the vaporizer 15 . The non-freezing heat medium circulating in the first heat medium circulation circuit 76 is cooled to near the freezing temperature of water and supplied to the first cooling coil 71 .

The precooled flue gas precooled to the precooling temperature T3 by the flue gas precooling device 60 flows into the gas passage 74c from the inlet 74a and circulates through the first heat medium circulation circuit 76 while traversing the first cooling coil 71. Heat is exchanged with the heat medium and cooled to near the freezing temperature of water, and most of the saturated steam is condensed into dry carbon dioxide gas. Large water droplets condensed with saturated steam fall on the drain pan 75, and small water droplets floating in the dry carbon dioxide gas are caught by the eliminator 72, fall on the drain pan 75, and are collected. flow out. The dry carbon dioxide that has passed through the eliminator 72 exchanges heat with the non-freezing heat medium circulating in the second heat medium circulation circuit 77 while traversing the second cooling coil 73, is cooled to a low temperature T1, and becomes recovered carbon dioxide. It flows out from the outflow port 74b and is liquefied in the carbon dioxide liquefier 66. Thus, according to the LNG vaporizer 12, the carbon dioxide contained in the precooled flue gas can be cooled to a low temperature T1 that is lower than the freezing temperature of water without freezing the saturated steam contained in the precooled flue gas. .

The reformer 21 of the steam reformer 20 is supplied with natural gas from the LNG vaporizer 12 and water or steam from the water supply device 22 . In the combustion furnace 23, the offgas supplied from the offgas holder 53 through the pipeline 52 and the natural gas supplied from the LNG vaporizer 10 through the pipelines 19 and 51 are combined with the oxygen supplied from the oxygen supply device 24. Combustion reaction heats the reformer 21 . In the reformer 21, the natural gas and steam are indirectly heated and undergo a steam reforming reaction under the reforming catalyst to produce a reformed gas containing hydrogen, carbon dioxide gas and carbon monoxide.

The reformed gas is cooled by the reformed gas cooling device 25 and supplied to the CO shift device 30 . The CO shift device 30 causes a shift reaction of carbon monoxide and water vapor contained in the reformed gas in the presence of a CO conversion catalyst, converts the reformed gas into a mixed gas containing hydrogen and carbon dioxide gas, and sends the mixed gas to a mixed gas cooling device 35 .

The hydrogen separator 40 separates the mixed gas cooled and dehumidified by the mixed gas cooling device 35 into hydrogen gas and off-gas, and supplies the hydrogen gas to the hydrogen utilization device 45 . The offgas is supplied to the combustion furnace 23 of the steam reformer 20 via the offgas holder 53 . The off-gas delivered from the hydrogen separation device 40 accompanies pulsation, but the off-gas holder 53 stores the off-gas to dampen the pulsation, so that it can stably undergo a combustion reaction with oxygen in the combustion furnace 23 .

In the first embodiment, natural gas obtained by vaporizing LNG and steam are steam-reformed in the steam reformer 20 to generate a reformed gas, and the reformed gas undergoes a shift reaction to produce hydrogen gas and carbon dioxide gas. A mixed gas is formed, the mixed gas is separated into hydrogen gas and off-gas by the hydrogen separator 40 , and the hydrogen gas is used by the hydrogen utilization device 45 . The off-gas and natural gas are supplied to the combustion furnace 23 and burned with oxygen supplied from the oxygen supply device 24 to generate the amount of heat required for steam reforming.
As a result, the carbon dioxide contained in the off-gas and the carbon dioxide generated by the combustion of the hydrogen gas, unreformed methane gas, and natural gas contained in the off-gas can be combined into the flue gas discharged from the combustion furnace 23, Efficient recovery of carbon dioxide becomes possible. By precooling the flue gas in the flue gas precooling device 60 and exchanging the cold heat of LNG with the LNG in the LNG vaporizer 12, the LNG is vaporized into natural gas and all the carbon dioxide generated in hydrogen production is removed. It can be cooled with LNG cold and recovered. Furthermore, since the off-gas and natural gas are combusted in the combustion furnace 23 of the steam reformer 20 with the oxygen supplied from the oxygen supply device 24, the combustion exhaust gas discharged from the combustion furnace 23 consists only of carbon dioxide gas and water vapor. It is possible to easily collect carbon dioxide gas. In addition, since the carbon dioxide gas is recovered at a low temperature, the liquefying power of the carbon dioxide gas can be reduced.

3. Configuration and effects of the second embodiment A carbon dioxide recovery type hydrogen production system 1b that utilizes LNG according to the second embodiment is provided with a water electrolysis device 70 that electrolyzes water, and steam reforms the generated oxygen. Since it is the same as the first embodiment except that it is supplied to the combustion furnace 23 of the device 20, the differences will be explained, and the same reference numerals will be given to the same components as the first embodiment. omitted.

In the second embodiment, as shown in FIG. 2, a water electrolysis device 70 is installed to generate oxygen and hydrogen by electrolyzing water with power derived from renewable energy such as solar power generation and wind power generation. The water electrolysis device 70 supplies the generated oxygen as the oxygen supply device 24 to the combustion furnace 23 of the steam reforming device 20 to burn the natural gas and off-gas supplied to the combustion furnace 23 .

As a result, the second embodiment has the same effects as the first embodiment, and the hydrogen and oxygen that are sent from the water electrolysis device 80 that electrolyzes water with the power 71 derived from renewable energy to the hydrogen utilization device 45 Both can be effectively utilized.

1a, 1b: carbon dioxide recovery type hydrogen production system utilizing LNG, 10: natural gas supply device, 11: LNG supply device, 12: LNG vaporization device, 19: pipeline, 20: steam reformer, 21: reform Qualityr, 22: Water supply device, 23: Combustion furnace, 24: Oxygen supply device, 25: Reformed gas cooling device, 30: CO shift device, 35: Mixed gas cooling device, 40: Hydrogen separation device, 45: Hydrogen Utilization device 50: Fuel supply circuit 51, 52: Pipe line 53: Off gas holder 60: Combustion exhaust gas precooling device 65: Carbon dioxide gas delivery device 66: Carbon dioxide gas liquefaction device 67 Carbon dioxide gas utilization device 70: Exhaust gas cooling device, 71: first cooling coil, 72: eliminator, 73: second cooling coil, 76: first heat medium circulation circuit, 77: second heat medium circulation circuit, 78: heat exchanger.

Claims

a natural gas supply device for vaporizing LNG supplied from the LNG supply device into natural gas and supplying the natural gas;
In the combustion furnace, the fuel and the oxygen supplied from the oxygen supply device burn and react to heat the reformer with the combustion heat, and the natural gas and steam supplied to the reformer are steamed in the presence of the reforming catalyst. a steam reformer for generating a reformed gas by a reforming reaction;
a reformed gas cooling device connected to the steam reformer for cooling the reformed gas to be supplied;
The reformed gas cooled from the reformed gas cooling device is supplied, and carbon monoxide gas and water vapor contained in the reformed gas are subjected to a shift reaction in the presence of a CO conversion catalyst to contain hydrogen gas and carbon dioxide gas. a shift reactor that produces a gas mixture;
a mixed gas cooling device connected to the shift reactor for cooling the supplied mixed gas;
A hydrogen separation device that separates hydrogen gas from the mixed gas that is connected to and supplied to the mixed gas cooling device, delivers the separated hydrogen gas, and delivers off-gas;
a fuel supply circuit connecting the hydrogen separator and the combustion furnace and supplying the offgas to the combustion furnace as the fuel;
a flue gas precooling device supplied with the flue gas generated by combustion of the fuel from the combustion furnace and precooling the flue gas into a precooled flue gas containing carbon dioxide gas and saturated steam;
provided in the natural gas supply device, the LNG is supplied from the LNG supply device, the pre-cooled flue gas is supplied from the flue gas pre-cooling device, and the LNG cold generated when the LNG is vaporized is combined with the pre-cooled flue gas. By exchanging heat between the LNG vaporizer, the LNG is vaporized into natural gas, and the precooled flue gas is cooled to condense the saturated steam, and then cooled to a low temperature to be recovered carbon dioxide and discharged. When,
a carbon dioxide gas delivery device for delivering the recovered carbon dioxide gas discharged from the LNG vaporizer;
A carbon dioxide recovery type hydrogen production system that utilizes LNG equipped with
We have a water electrolyzer that generates hydrogen and oxygen by electrolyzing water with power derived from renewable energy.
2. The carbon dioxide gas recovery type hydrogen production system utilizing LNG according to claim 1, wherein said oxygen generated by said water electrolysis device as said oxygen supply device is supplied to said combustion furnace.
The carbon dioxide recovery type hydrogen production system utilizing LNG according to claim 1 or 2, wherein an off-gas holder for storing the off-gas is provided between the hydrogen separation device of the fuel supply circuit and the combustion furnace.
4. The fuel supply circuit according to any one of claims 1 to 3, wherein the fuel supply circuit includes a conduit connecting the natural gas supply device and the combustion furnace and supplying the natural gas to the combustion furnace as the fuel. A carbon dioxide recovery type hydrogen production system that utilizes LNG.
The carbon dioxide gas recovery type hydrogen production system utilizing LNG according to any one of claims 1 to 4, wherein the carbon dioxide gas delivery device is provided with a carbon dioxide gas liquefaction device for liquefying the low-temperature recovered carbon dioxide gas.
The LNG vaporizer comprises a vaporizer and an exhaust gas cooler,
The vaporizer is supplied with LNG from the LNG supply device on the low temperature side, and the non-freezing heat medium flowing through the second cooling coil and the heat exchanger provided in the exhaust gas cooling device is circulated on the high temperature side, and the LNG LNG cold heat is heat exchanged between and the antifreezing heat medium to vaporize the LNG into natural gas,
The exhaust gas cooling device has a first cooling coil, an eliminator, and a second cooling coil arranged in series from one side to the other side, and the precooled flue gas flows in from the inlet on the one side and exits on the other side. a second heat medium circulation circuit in which the antifreezing heat medium circulates through the second cooling coil, the low temperature side of the heat exchanger, and the high temperature side of the vaporizer; a first cooling coil and a first heat medium circulation circuit in which an antifreezing heat medium circulates through the high temperature side of the heat exchanger; a condensed water outflow part that collects captured condensed water and causes it to flow out of the gas passage, wherein the precooled flue gas is cooled by the first cooling coil to condense the saturated steam, and then the second 6. The carbon dioxide recovery type hydrogen production system utilizing LNG according to any one of claims 1 to 5, wherein the carbon dioxide gas is cooled to a low temperature by a cooling coil and discharged as recovered carbon dioxide gas.