A carbon emission reduction device for producing hydrogen from natural gas

Abstract

The present application belongs to the field of energy utilization technology, and in particular, relates to a carbon emission reduction device for producing hydrogen from natural gas. Existing devices need to capture, utilize / seal the carbon dioxide in the tail gas. The present application provides a carbon emission reduction device for producing hydrogen from natural gas, including a water electrolysis module, a natural gas reforming module, a tail gas treatment module, a water treatment module and a power supply module connected in sequence, the water treatment module is connected to the natural gas reforming module, the water treatment module is connected to the water electrolysis module, the power supply module is connected to the natural gas reforming module, the power supply module is connected to the water electrolysis module, and the power supply module is connected to the tail gas treatment module. Oxygen-enriched combustion technology makes the carbon dioxide concentration in the tail gas higher, which is convenient for the subsequent low-cost capture, utilization or storage of carbon dioxide, making hydrogen production from fossil energy more environmentally friendly.

Description

Technical Field

[0001] The present application belongs to the field of energy utilization technology, and in particular, relates to a carbon emission reduction device for producing hydrogen from natural gas. Background Art

[0002] With the development goals of carbon peak and carbon neutrality in my country, the pace of carbon reduction will surely advance in great strides. Hydrogen, as a zero-carbon energy carrier, is gaining more and more attention. It is estimated that 20% of the world's carbon dioxide emissions reduction can be achieved through hydrogen substitution in 2050. The sources of hydrogen are divided into industrial by-product hydrogen, fossil fuel hydrogen production, and water electrolysis hydrogen production. At present, more than 95% of the world's hydrogen production comes from fossil fuel reforming, mainly natural gas reforming, and this production process will inevitably cause carbon dioxide emissions. In view of the goal of carbon neutrality, the capture and storage of carbon dioxide must be the only way to produce hydrogen from fossil fuels in the future.

[0003] The traditional natural gas reforming hydrogen production process generally includes natural gas desulfurization and denitrification, high-temperature reforming, pressure swing adsorption and other processes to obtain hydrogen with a purity of 99.9%. The heat in the high-temperature reforming furnace is generally provided by the combustion of air and fuel gas, and the main component of air is nitrogen (about 78%), which causes a large amount of heat released by fuel combustion to be absorbed by nitrogen, resulting in energy waste. At the same time, air as a combustion aid causes a large amount of nitrogen in the combustion exhaust gas. Although some studies have recycled the heat of this part of nitrogen, the specific heat capacity of nitrogen is small and there is a lot of loss in heat transfer. Considering the full combustion heat generation of combustion, it is very necessary to achieve efficient hydrogen production and reduce the nitrogen content in the combustion aid. At the same time, due to the presence of nitrogen, the concentration of carbon dioxide in the exhaust gas is low, generally considered to be 9%, which is not conducive to the capture of carbon dioxide. If a capture system is used for capture, the cost is high. Therefore, in order to achieve the goal of carbon neutrality and realize the production of green hydrogen from fossil fuels, it is necessary to capture, utilize / store the carbon dioxide in the exhaust gas. There is an urgent need for a natural gas hydrogen production process that is convenient, low-cost and efficient in carbon capture. Summary of the invention

[0004] 1. Technical issues to be solved

[0005] Based on the existing natural gas reforming hydrogen production, a part of the natural gas mixed with air will be drawn out and passed into the combustion furnace to burn to provide heat for the reforming reaction. The main component of air is nitrogen (about 78%), which causes a large amount of heat released by fuel combustion to be absorbed by nitrogen. Although some studies have recycled the heat of this part of nitrogen, the specific heat capacity of nitrogen is small, and there is a lot of loss in heat transfer. Considering the full combustion heat generation, it is very necessary to achieve efficient hydrogen production and reduce the nitrogen content in the combustion aid. At the same time, due to the presence of nitrogen, the concentration of carbon dioxide in the exhaust gas is low. In the existing natural gas reforming hydrogen production, the exhaust gas treatment scheme generally does not include the treatment of carbon dioxide, which causes a large amount of carbon dioxide emissions. In order to achieve the goal of carbon neutrality and realize the production of green hydrogen from fossil fuels, it is necessary to capture, utilize / seal the carbon dioxide in the exhaust gas. The present application provides a carbon emission reduction device for hydrogen production from natural gas.

[0006] 2. Technical solution

[0007] In order to achieve the above-mentioned objectives, the present application provides a carbon emission reduction device for producing hydrogen from natural gas, comprising a water electrolysis module, a natural gas reforming module, a tail gas treatment module, a water treatment module and a power supply module connected in sequence, the water treatment module being connected to the natural gas reforming module, the water treatment module being connected to the water electrolysis module, the power supply module being connected to the natural gas reforming module, the power supply module being connected to the water electrolysis module, and the power supply module being connected to the tail gas treatment module; the water electrolysis module is used to produce oxygen, provide a combustion aid for the natural gas reforming module, and assist in the preparation of hydrogen; the natural gas reforming module is used to prepare hydrogen; the tail gas treatment module is used to reduce carbon dioxide emissions; the water treatment module is used to provide circulating water for the water electrolysis module, the natural gas reforming module and the tail gas treatment module; the power supply module is used to provide electricity for the water electrolysis module, the tail gas treatment module and the water treatment module.

[0008] Another embodiment provided by the present application is: the natural gas reforming module comprises a first preheater, a desulfurizer, a second preheater, a reformer and a pressure swing adsorber connected in sequence, the first preheater is fed with natural gas, the reformer is fed with the natural gas, the reformer is connected to the water electrolysis module, and the first preheater is connected to the water treatment module.

[0009] Another embodiment provided by the present application is: the water electrolysis module includes an oxygen buffer tank, an electrolyzer and a hydrogen purifier connected in sequence, the oxygen buffer tank is connected to the reformer, and the electrolyzer is connected to the power supply module.

[0010] Another embodiment provided by the present application is: the exhaust gas treatment module includes a compressor unit, an interstage cooler and a second dehydrator connected in sequence, the second dehydrator is connected to the compressor unit, the compressor unit is connected to the power supply module, and the interstage cooler is connected to the water treatment module.

[0011] Another implementation manner provided by the present application is that the compressor unit is a multi-stage centrifugal compressor, and each stage of the centrifugal compressor is connected to the interstage cooler or the second dehydrator.

[0012] Another embodiment provided by the present application is: the water treatment module includes a steamer, a cooler, a first dehydrator, a water storage tower, a water supply pump and a water purifier connected in sequence, the reformer, the steamer and the pressure swing adsorber are connected in sequence, the cooler is connected to the first preheater, the cooler is connected to the electrolyzer, the cooler is connected to the interstage cooler, the first dehydrator is connected to the compressor unit, the first dehydrator is connected to the water storage tower, the water storage tower is connected to the second dehydrator, and the water supply pump is connected to the power supply module.

[0013] Another implementation manner provided by the present application is that the power supply module is a renewable energy power plant.

[0014] 3. Beneficial effects

[0015] Compared with the prior art, the carbon emission reduction device for producing hydrogen from natural gas provided in this application has the following beneficial effects:

[0016] The carbon emission reduction device for producing hydrogen from natural gas provided in this application is a carbon emission reduction device for producing hydrogen from natural gas by combining water electrolysis with natural gas reforming; it innovatively combines hydrogen production technology, oxygen-enriched combustion technology and carbon capture technology. It organically combines the two current mainstream technologies of hydrogen production from natural gas reforming and hydrogen production from water electrolysis to improve the total amount and efficiency of hydrogen production.

[0017] The carbon emission reduction device for producing hydrogen from natural gas provided in the present application utilizes the product oxygen during the electrolysis of water to produce hydrogen for oxygen-enriched combustion during the reforming process, thereby improving the combustion efficiency of the fuel and reducing the consumption of fossil energy.

[0018] The carbon emission reduction device for producing hydrogen from natural gas provided in the present application uses oxygen-enriched combustion technology to increase the concentration of carbon dioxide in the exhaust gas, facilitating subsequent low-cost capture, utilization or storage of carbon dioxide, making hydrogen production from fossil energy more environmentally friendly. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 It is a simple schematic diagram of the carbon emission reduction device for producing hydrogen from natural gas in the present application;

[0020] Figure 2It is a schematic diagram of the natural gas reforming hydrogen production module process of the present application;

[0021] Figure 3 It is a schematic diagram of the water electrolysis module process of the present application;

[0022] Figure 4 It is a schematic diagram of the tail gas treatment module flow of the present application;

[0023] Figure 5 It is a schematic flow chart of the carbon emission reduction device for producing hydrogen from natural gas in the present application. DETAILED DESCRIPTION

[0024] Hereinafter, the specific embodiments of the present application will be described in detail with reference to the accompanying drawings. According to these detailed descriptions, those skilled in the art can clearly understand the present application and can implement the present application. Without violating the principles of the present application, the features in the various embodiments can be combined to obtain new implementations, or certain features in certain embodiments can be replaced to obtain other preferred implementations.

[0025] See also Figures 1 to 5 The present application provides a carbon emission reduction device for producing hydrogen from natural gas, comprising a water electrolysis module, a natural gas reforming module, a tail gas treatment module, a water treatment module and a power supply module connected in sequence, wherein the water treatment module is connected to the natural gas reforming module, the water treatment module is connected to the water electrolysis module, the power supply module is connected to the natural gas reforming module, the power supply module is connected to the water electrolysis module, and the power supply module is connected to the tail gas treatment module; Figure 1 As shown, the device is mainly composed of five modules: natural gas reforming hydrogen production module, water electrolysis module, tail gas treatment module, water treatment module and power supply module. Natural gas reforming hydrogen production module, this module is responsible for the main task of hydrogen production, and hydrogen is produced by mixing methane in natural gas with water vapor. Water electrolysis module, on the one hand, this module is used to produce oxygen, providing rich combustion aids for the oxygen-enriched combustion technology in the natural gas reforming module, on the other hand, this module also undertakes the work of assisting hydrogen production. Tail gas treatment module, which treats the tail gas mainly composed of carbon dioxide produced by oxygen-enriched combustion, reduces carbon dioxide emissions or even zero emissions. Water treatment module, this module plays an important role in energy recovery and utilization, and provides circulating water for the above three modules. At the same time, it also undertakes the task of providing the required water vapor for the natural gas reforming module and providing pure water for water electrolysis. Power supply module, which provides power supply for the above-mentioned power supply equipment.

[0026] On the basis of hydrogen production by natural gas reforming, a water electrolysis module is added to improve the hydrogen production capacity and efficiency. By using the oxygen generated by water electrolysis, oxygen-enriched combustion technology is implemented on the traditional natural gas hydrogen production device, which increases the flame temperature of fuel combustion, improves the efficiency of heat utilization, reduces the consumption of fossil energy, obtains high-concentration carbon dioxide, facilitates the capture of greenhouse gas carbon dioxide, and realizes zero-emission hydrogen production.

[0027] Further, the natural gas reforming module comprises a first preheater 1, a desulfurizer 2, a second preheater 3, a reformer 4 and a pressure swing adsorber 6 connected in sequence, the first preheater 1 is fed with natural gas, and the natural gas is fed with the reformer 4. The reformer 4 is connected to the water electrolysis module, and the first preheater 1 is connected to the water treatment module.

[0028] like Figure 2 As shown, a part of the natural gas inflow is introduced into the reformer 4 for oxygen-enriched combustion to provide heat for the reforming reaction of natural gas and water vapor; the other part of the inflow is sequentially processed by the first preheater 1, the desulfurizer 2, and the second preheater 3 for preliminary treatment of the natural gas, and then enters the reformer 3 for chemical reactions such as reforming reaction and carbon monoxide conversion reaction with water vapor. The main component of the reformed gas is hydrogen, followed by water vapor, carbon monoxide, carbon dioxide, etc. The reformed mixed gas is introduced into the pressure swing adsorber 6 for hydrogen purification, and the remaining components are introduced into the reformer 4 for oxygen-enriched combustion to generate heat.

[0029] Furthermore, the water electrolysis module comprises an oxygen buffer tank 16, an electrolyzer 15 and a hydrogen purifier which are connected in sequence, the oxygen buffer tank 16 is connected to the reformer 4, and the electrolyzer 15 is connected to the power supply module.

[0030] like Figure 3 The electrolytic cell 15 shown is preferably an alkaline electrolytic cell 15 with mature technology and low cost. Pure water is introduced into the electrolytic cell 15, and oxygen is discharged from the cathode. The generated oxygen can be buffered and then introduced into the reformer 4 for oxygen-enriched combustion. After electrolysis, hydrogen is generated at the anode. When the hydrogen flows out, it carries water and electrolyte solution, and needs to be further purified to obtain product hydrogen.

[0031] Furthermore, the exhaust gas treatment module includes a compressor unit 9, an interstage cooler 10 and a second dehydrator 11 connected in sequence, the second dehydrator 11 is connected to the compressor unit 9, the compressor unit 9 is connected to the power supply module, and the interstage cooler 10 is connected to the water treatment module.

[0032] like Figure 4As shown, the main component of the tail gas of the reformer 4 is carbon dioxide, followed by water vapor. In CCUS projects, carbon dioxide is generally compressed to a supercritical state for pipeline transportation. The compressor unit 9 is preferably a multi-stage centrifugal compressor to facilitate large-scale gas processing. In this module, each stage of the compressor, cooler and dehydrator are arranged alternately. After the tail gas is compressed once, it is cooled and cooled, a part of the water is removed, and high-purity supercritical carbon dioxide (sCO2) is obtained after multi-stage processing.

[0033] Furthermore, the water treatment module includes a steamer 5, a cooler 7, a first dehydrator 8, a water storage tower 12, a water supply pump 13 and a water purifier 14 connected in sequence, the reformer 4, the steamer 5 and the pressure swing adsorber 6 are connected in sequence, the cooler 7 is connected to the first preheater 1, the cooler 7 is connected to the electrolyzer 15, the cooler 7 is connected to the interstage cooler 10, the first dehydrator 8 is connected to the compressor unit 9, the first dehydrator 8 is connected to the water storage tower 12, the water storage tower 12 is connected to the second dehydrator 11, and the water supply pump 14 is connected to the power supply module.

[0034] The coupling between water treatment module and other modules is more complicated. Figure 5 The water treatment module and the power supply module are explained. At the same time, the entire device process is also explained again. Figure 5 As shown, the renewable energy power plant 17 provides electric energy for various power-consuming equipment in the device process, such as the electric compressor unit 9, the water supply pump 13, the electrolyzer 15 and other equipment. After the water supply pump 13 is powered on, the water in the water storage tower 12 is pumped into the water purifier 14 through the water supply pump 13, and then passed into the interstage cooler 10 to cool the high-temperature gas after the compressor is pressurized. After the water is heated in the interstage cooler 10, a part of it is passed into the electrolyzer 15 for electrolysis to produce oxygen and hydrogen. The other part of the water enters the pipe process of the cooler 7 to absorb the remaining heat in the tail gas again, and then enters the steamer 5, and is further heated to generate water vapor and then merged into the reformer 4 for reforming reaction to produce hydrogen. The unreacted water vapor enters the pressure swing adsorber 6 with the multi-component gas mainly composed of hydrogen, and is separated from the hydrogen. Then, it returns to the reformer 4 with gases such as carbon monoxide and carbon dioxide for combustion, and then flows into the shell of the second preheater 3, the first preheater 1, i.e., the heat exchanger, and the cooler 7 with the tail gas in sequence, providing heat for the natural gas gas flow and the process of producing water vapor. After passing through the cooler 7, the water vapor is cooled into liquid water, separated from the tail gas flow through the first dehydrator 8, and the liquid water is recovered to the water storage tower 12. It is difficult to completely remove the water from the tail gas flow after one dehydration, so a cooling and dehydration device is provided between the two stages of the compressor unit 9. Through inter-stage dehydration, all the water in the tail gas flow is removed and also recovered to the water storage tower 12, so that the water cycle is completed.

[0035] Example

[0036] The natural gas flow is divided into two parts. One part enters the reformer 4 for oxygen-enriched combustion to provide heat for the reforming reaction and the carbon monoxide conversion reaction. The other part of the natural gas is heated in the first preheater 1, i.e., the heat exchanger, and then enters the desulfurizer 2 for desulfurization. The desulfurized natural gas enters the second preheater 3 for heating, and enters the reformer 4 for reforming reaction after reaching the reforming temperature. After the reforming reaction, the multi-component gas flow mainly composed of hydrogen enters the pressure swing adsorber 6, where the hydrogen is purified by pressure swing adsorption, and the remaining components are refluxed to the reformer 4 for combustion. The high-temperature tail gas (mainly carbon dioxide) generated by the combustion of the reforming furnace 4 is passed into the second preheater 3 and the heat exchanger to heat the natural gas flow, and then passed into the cooler 7, where the heat is used to produce water vapor for the reforming reaction, thereby realizing the cascade utilization of energy. The cooled tail gas flow enters the first dehydrator 8 to separate the water and carbon dioxide gas in the tail gas flow, and the separated carbon dioxide enters the compressor unit 9 for pressurization, cooling, and dehydration to obtain supercritical carbon dioxide, which is the carbon path. The liquid water separated from the first dehydrator 8 and the second dehydrator 11 flows back to the water storage tower 12. Various power-consuming equipment in the device process, such as the electric compressor unit 9, the water supply pump 13, the electrolyzer 15 and other equipment, are provided with electric energy by the renewable energy power plant 17. After the water supply pump 13 is powered on, the water supply pump 13 pumps the water in the water storage tower 12 into the water purifier 14. After the water is purified, it is passed into the interstage cooler 10 to cool the compressor unit. Then the water is divided into two paths, one of which enters the electrolyzer 15 to electrolyze and produce hydrogen and oxygen. The oxygen flow is passed into the reformer 4 after buffering and stabilizing the flow, and the fuel gas is oxygen-enriched combustion is carried out to improve the thermal efficiency of combustion. The other water after the interstage cooler 10 is passed into the cooler 7 to cool the tail gas, and then enters the steamer 5 to produce water vapor, and the water vapor enters the reformer 4 for reforming reaction. The unreacted water vapor enters the pressure swing adsorber along with the multi-component gas mainly composed of hydrogen, and is separated from the hydrogen. Then, it returns to the reformer with gases such as carbon monoxide and carbon dioxide for combustion, and then flows into the shell of the preheater 3, the heat exchanger 1 and the cooler 7 in sequence with the tail gas, providing heat for the natural gas gas flow and the process of producing water vapor. After passing through the cooler 7, the water vapor is cooled into liquid water, separated from the tail gas flow through the first dehydrator 8, and the liquid water is recovered to the water storage tower 12. It is difficult to completely remove the water from the tail gas flow after one dehydration, so a cooling and dehydration device is installed between the two stages of the compressor unit. Through inter-stage dehydration, all the water in the tail gas flow is removed and also recovered to the water storage tower 12, so that the water cycle is completed.

[0037] Natural gas reforming to produce hydrogen requires a large amount of heat. The heat in traditional natural gas hydrogen production is provided by the combustion of a mixture of natural gas and air. This device adds a water electrolysis module on the basis of the original natural gas reforming to produce hydrogen. The oxygen obtained in the electrolysis process is introduced into the reforming furnace to allow the fuel natural gas to undergo oxygen-enriched combustion. The exhaust gas after the oxygen-enriched combustion is treated by cooling, compression, dehydration, etc. to obtain high-purity carbon dioxide, thereby achieving high-flow and high-efficiency hydrogen production with zero carbon emissions.

[0038] Although the present application is described above with reference to specific embodiments, it should be understood by those skilled in the art that many modifications may be made to the configurations and details disclosed in the present application within the principles and scope disclosed in the present application. The scope of protection of the present application is determined by the appended claims, and the claims are intended to cover all modifications included in the equivalent literal meaning or scope of the technical features in the claims.

Claims

1. A carbon emission reduction device for producing hydrogen from natural gas, characterized in that: It includes a water electrolysis module, a natural gas reforming module, a tail gas treatment module, a water treatment module and a power supply module connected in sequence, wherein the water treatment module is connected to the natural gas reforming module, the water treatment module is connected to the water electrolysis module, the power supply module is connected to the natural gas reforming module, the power supply module is connected to the water electrolysis module, and the power supply module is connected to the tail gas treatment module; The water electrolysis module is used to produce oxygen, provide a combustion aid for the natural gas reforming module, and assist in the preparation of hydrogen; the water electrolysis module comprises an oxygen buffer tank, an electrolyzer and a hydrogen purifier connected in sequence, the oxygen buffer tank is connected to the reformer, and the electrolyzer is connected to the power supply module; The natural gas reforming module is used to prepare hydrogen; the natural gas reforming module comprises a first preheater, a desulfurizer, a second preheater, a reformer and a pressure swing adsorber connected in sequence, the first preheater is fed with natural gas, the reformer is fed with the natural gas, the reformer is connected to the water electrolysis module, and the first preheater is connected to the water treatment module; The tail gas treatment module is used to reduce carbon dioxide emissions; the tail gas treatment module includes a compressor unit, an interstage cooler and a second dehydrator connected in sequence, the second dehydrator is connected to the compressor unit, the compressor unit is connected to the power supply module, and the interstage cooler is connected to the water treatment module; The water treatment module is used to provide circulating water for the water electrolysis module, the natural gas reforming module and the tail gas treatment module; the water treatment module includes a steamer, a cooler, a first dehydrator, a water storage tower, a water supply pump and a water purifier connected in sequence, the reformer, the steamer and the pressure swing adsorber are connected in sequence, the cooler is connected to the first preheater, the cooler is connected to the electrolyzer, the cooler is connected to the interstage cooler, the first dehydrator is connected to the compressor unit, the first dehydrator is connected to the water storage tower, the water storage tower is connected to the second dehydrator, the water supply pump is connected to the compressor unit, and the water supply pump is connected to the power supply module; The power supply module is used to provide power to the water electrolysis module, the tail gas treatment module and the water treatment module.

2. The carbon emission reduction device for producing hydrogen from natural gas according to claim 1, characterized in that: The compressor unit is a multi-stage centrifugal compressor, and each stage of the centrifugal compressor is connected to the interstage cooler or the second dehydrator.

3. The carbon emission reduction device for producing hydrogen from natural gas according to any one of claims 1 to 2, characterized in that: The power supply module is a renewable energy power plant.

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