Natural gas hydrogen production system

Abstract

The utility model relates to a natural gas hydrogen production system which comprises a hydrogen production unit and a steam generation unit, the hydrogen production unit comprises a natural gas source, a reformer and a desulfurization tank, the reformer is provided with a convection section, a reaction section and a heating part, the heating part is used for heating the convection section and the reaction section, and the natural gas source is sequentially communicated with the convection section, the desulfurization tank and the reaction section. The prepared hydrogen is discharged from the reaction section, and the steam generation unit is communicated with the reaction section and is used for providing steam. Compared with the prior art, the natural gas hydrogen production system provided by the utility model uses natural gas to prepare hydrogen, firstly uses the desulfurization tank to remove impurities such as hydrogen sulfide in the natural gas to avoid catalyst poisoning, and then is mixed with water vapor and introduced into the reaction section to react to prepare hydrogen; the hydrogen is prepared by using cheap water and natural gas as raw materials, so that the production cost of the hydrogen is greatly reduced.

Description

Technical Field

[0001] The utility model relates to the technical field of hydrogen production, in particular to a natural gas hydrogen production system. Background Art

[0002] Hydrogen is likely to become an important energy source on the world energy stage in the 21st century, and the production, storage, transportation and application technology of hydrogen will also become the focus of attention in the 21st century. Hydrogen has the characteristics of high combustion calorific value, which is 3 times that of gasoline, 3.9 times that of alcohol, and 4.5 times that of coke. The product of hydrogen combustion is water, and no pollutants are produced.

[0003] The most common way to produce hydrogen is to electrolyze water. This method consumes a lot of electricity, resulting in high costs for hydrogen production, which limits the promotion and use of hydrogen as a new energy source. Utility Model Content

[0004] In view of this, it is necessary to provide a natural gas hydrogen production system to solve the technical problem of high cost of preparing hydrogen by electrolyzing water in the prior art.

[0005] The utility model provides a natural gas hydrogen production system, which comprises: a hydrogen production unit and a steam generation unit, the hydrogen production unit comprises a natural gas source, a reformer, and a desulfurization tank, the reformer has a convection section, a reaction section and a heating part, the heating part is used to heat the convection section and the reaction section, the natural gas source is connected with the convection section, the desulfurization tank and the reaction section in sequence, the produced hydrogen is discharged from the reaction section, and the steam generation unit is connected with the reaction section to provide water vapor.

[0006] Furthermore, the hydrogen production unit also includes a natural gas compressor and a raw gas buffer tank, and the natural gas source is connected to the natural gas compressor, the raw gas buffer tank and the convection section in sequence.

[0007] Furthermore, the hydrogen production unit also includes a cooler, which is connected to the outlet of the reaction section to cool the produced hydrogen.

[0008] Furthermore, the hydrogen production unit also includes a gas-liquid separator, which is connected to the outlet of the cooler to separate water from the hydrogen.

[0009] Furthermore, the hydrogen production unit also includes a PSA hydrogen extraction device, the inlet of the PSA hydrogen extraction device is connected to the outlet of the gas-liquid separator, the PSA hydrogen extraction device has a hydrogen outlet and a miscellaneous gas outlet, the hydrogen outlet is used to discharge the produced hydrogen, and the miscellaneous gas outlet is connected to the heating part to burn the miscellaneous gas.

[0010] Furthermore, the hydrogen outlet is also connected to the raw gas buffer tank to introduce part of the hydrogen into the raw gas buffer tank.

[0011] Furthermore, the natural gas source is also connected to the heating part for inputting natural gas into the heating part for combustion.

[0012] Furthermore, the hydrogen production unit also includes a fuel gas buffer tank, and the natural gas source is also connected to the heating part via the fuel gas buffer tank.

[0013] Furthermore, the steam generating unit comprises a desalted water source and a steam generator, the desalted water source is connected to the steam generator, and the steam generator is connected to the reaction section.

[0014] Furthermore, the reformer also includes a superheater, the steam generator and the desulfurization tank are connected to the inlet of the superheater, the outlet of the superheater is connected to the reaction section, and the heating part also heats the superheater.

[0015] Compared with the prior art, the natural gas hydrogen production system provided by the utility model uses natural gas to prepare hydrogen. A desulfurization tank is first used to remove impurities such as hydrogen sulfide in the natural gas to avoid catalyst poisoning, and then the natural gas is mixed with water vapor and introduced into a reaction section for reaction to produce hydrogen. Since cheap water and natural gas are used as raw materials to prepare hydrogen, the production cost of hydrogen is greatly reduced.

[0016] The above description is only an overview of the technical solution of the utility model. In order to more clearly understand the technical means of the utility model and implement it according to the contents of the specification, the preferred embodiment of the utility model is described in detail as follows with the accompanying drawings. The specific implementation method of the utility model is given in detail by the following embodiments and their drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The drawings described herein are used to provide a further understanding of the present invention and constitute a part of the present application. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation on the present invention. In the drawings:

[0018] FIG1 is a schematic structural diagram of a preferred embodiment of a natural gas hydrogen production system provided by the present invention. DETAILED DESCRIPTION

[0019] The preferred embodiments of the present invention are described in detail below in conjunction with the accompanying drawings, wherein the accompanying drawings constitute a part of the present application and are used together with the embodiments of the present invention to illustrate the principles of the present invention, but are not used to limit the scope of the present invention.

[0020] See also Figure 1The utility model provides a natural gas hydrogen production system. The natural gas hydrogen production system includes a hydrogen production unit and a steam generation unit. The hydrogen production unit is used to prepare hydrogen, and includes a natural gas source 11, a reformer 12, and a desulfurization tank 13. The reformer 12 has a convection section, a reaction section, and a heating part, and the heating part is used to heat the convection section and the reaction section. The natural gas source 11 is connected to the convection section, the desulfurization tank 13, and the reaction section in sequence. The steam generation unit is connected to the reaction section to provide water vapor.

[0021] The natural gas first passes through the convection section, where it is heated, and then enters the desulfurization tank 13, where impurities, mainly hydrogen sulfide, are removed under the action of a catalyst. Then, it is mixed with water vapor and passed into the reaction section, where methane and water vapor react to produce hydrogen, which is then discharged from the reaction section. Since cheap water and natural gas are used as raw materials to produce hydrogen, the production cost of hydrogen is greatly reduced.

[0022] In some embodiments, the natural gas source 11 is used to provide natural gas, which may be a natural gas pipeline or a natural gas storage tank. The convection section and the reaction section in the reformer 12 are not connected to each other, and the convection section can be regarded as a gas channel for natural gas to pass through and be heated in the process. The reaction section is the area where methane reacts with water vapor, and a corresponding catalyst is arranged inside to promote the reaction. And the reaction is an endothermic reaction, and the heat is provided by the heating unit. The desulfurization tank 13 is used to remove impurities mainly composed of hydrogen sulfide in the natural gas to avoid poisoning of the catalyst in the reaction section.

[0023] In some embodiments, the hydrogen production unit further includes a natural gas compressor 14 and a raw gas buffer tank 15, and the natural gas source 11 is connected to the natural gas compressor 14, the raw gas buffer tank 15 and the convection section in sequence. The natural gas compressor 14 is used to pressurize the natural gas provided by the natural gas source and transport it to the raw gas buffer tank 15. The raw gas buffer tank 15 is provided to solve the problem of unstable pressure and flow of the natural gas provided by the natural gas source 11.

[0024] In some embodiments, the natural gas source 11 is also connected to the heating unit, and is used to input natural gas into the heating unit for combustion to generate heat. That is, the energy source for heating the heating unit is also provided by cheap natural gas.

[0025] In a preferred embodiment, the hydrogen production unit further comprises a fuel gas buffer tank 16, and the natural gas source 11 is also connected to the heating unit via the fuel gas buffer tank 16. The fuel gas buffer tank 16 is also used to solve the problem of unstable pressure and flow of the natural gas provided by the natural gas source 11.

[0026] In some embodiments, the hydrogen production unit further includes a cooler 17, which is connected to the outlet of the reaction section to cool the produced hydrogen.

[0027] In some embodiments, the hydrogen production unit further includes a gas-liquid separator 18, which is connected to the outlet of the cooler 17. While the cooler 17 cools the hydrogen, it also liquefies the unreacted water vapor into gas, and the gas-liquid separator 18 can separate the liquefied water from the hydrogen.

[0028] In some embodiments, the hydrogen production unit further includes a PSA hydrogen extraction device 19, and the inlet of the PSA hydrogen extraction device 19 is connected to the outlet of the gas-liquid separator 18. PSA stands for Pressure Swing Adsorption. It is a method for recovering or purifying hydrogen from a hydrogen-rich gas stream. By changing the operating conditions, hydrogen of different purities can be produced, and the purity of hydrogen can reach 99.99%. The PSA hydrogen extraction device 19 has a hydrogen outlet and a miscellaneous gas outlet, and the hydrogen outlet is used to discharge the produced high-purity hydrogen. The miscellaneous gas outlet is connected to the heating part, which is used to introduce the separated impurity gas, mainly unreacted natural gas, into the heating part for combustion treatment. Make full use of natural gas to save resources and reduce emissions.

[0029] In some embodiments, the hydrogen outlet is also connected to the raw gas buffer tank 15, so as to introduce part of the produced hydrogen as circulating hydrogen into the raw gas buffer tank 15 again, mix it with the raw natural gas, and participate in the impurity removal reaction in the desulfurization tank 13. The circulating hydrogen is provided to provide a stable hydrogen source for the desulfurization and impurity removal steps.

[0030] In some embodiments, the steam generating unit includes a desalted water source 21 and a steam generator 22, wherein the desalted water source 21 is connected to the steam generator 22, and the steam generator 22 is connected to the reaction section. The desalted water source 21 provides desalted water, which can be obtained by removing soluble salts from tap water through a desalting device. The use of desalted water can prevent scaling of the steam generator 22. The steam generator 22 is used to mix water vapor into the natural gas after impurities are removed, and is preferably connected to a pipeline between the reaction section and the desulfurization tank 13.

[0031] In a preferred embodiment, the reformer 12 further includes a superheater, the steam generator 22 and the desulfurization tank 13 are connected to the inlet of the superheater, the outlet of the superheater is connected to the reaction section, and the heating part also heats the superheater. After the water vapor and natural gas are mixed, they first enter the superheater for preheating, and then enter the reaction section for reaction.

[0032] The main components of natural gas are alkanes, of which methane accounts for the vast majority, with a small amount of ethane, propane and butane. In addition, there are generally hydrogen sulfide, carbon dioxide, nitrogen and water vapor, a small amount of carbon monoxide and trace amounts of rare gases. Before natural gas is delivered to the end user, mercaptan (RSH), tetrahydrothiophene, etc. are used to add odor to the natural gas to help with leak detection. In addition, organic sulfides and hydrogen sulfide (H2S) are common impurities and must be removed in advance in most cases where natural gas is used.

[0033] Taking the natural gas pipeline network as the natural gas source 11 as an example, the natural gas at room temperature and pressure of about 1.0~1.6MPa(G) from the pipeline network is pressurized to 2.3~2.5MPa(G) by the natural gas compressor 14, mixed with circulating hydrogen and enters the raw gas buffer tank 15 as raw gas. The raw gas is then adjusted in flow rate and enters the convection section of the converter 12, heated to 360℃ and enters the desulfurization tank 13. With the addition of zinc oxide and cobalt-molybdenum hydrogenation catalyst, the sulfur in the raw gas is reduced to below 0.1ppm. The main reaction process is as follows:

[0034] RSH+H2→H2S+RH

[0035] C4H4S+4H2→H2S+ C4H 10

[0036] H2S+ZnO→ZnS+H2O

[0037] This process can also treat chlorine, arsenic, cyanide, and phosphide to below 0.1 PPm through similar reactions.

[0038] The desulfurized raw gas is mixed with water vapor in a certain ratio (molar ratio is about 1:3.2) and enters the superheater to be further preheated to 580°C. Then it enters the reaction section. In the catalyst bed, methane reacts with water vapor to generate mixed gases such as H2, CO, and CO2. The heat required for methane conversion is provided by the combustion of natural gas in the heating section. The main reaction process is as follows:

[0039] CH4+H2O (gas) → CO+H2

[0040] CO + H2O (gas) → CO2 + H2

[0041] The mixed gas is cooled to below 40°C by the cooler 17, and then separated by the gas-liquid separator 18 before entering the PSA process.

[0042] Compared with the prior art, the natural gas hydrogen production system provided by the utility model uses natural gas to prepare hydrogen. A desulfurization tank is first used to remove impurities such as hydrogen sulfide in the natural gas to avoid catalyst poisoning, and then the natural gas is mixed with water vapor and introduced into a reaction section for reaction to produce hydrogen. Since cheap water and natural gas are used as raw materials to prepare hydrogen, the production cost of hydrogen is greatly reduced.

[0043] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by any technician familiar with the technical field within the technical scope disclosed in the present invention should be included in the protection scope of the present invention.

Claims

1. A natural gas hydrogen production system, characterized in that: It includes: A hydrogen production unit and a steam generation unit, wherein the hydrogen production unit comprises a natural gas source, a reformer, and a desulfurization tank. The reformer comprises a convection section, a reaction section, and a heating unit. The heating unit is used to heat the convection section and the reaction section. The natural gas source is sequentially connected to the convection section, the desulfurization tank, and the reaction section. The produced hydrogen is discharged from the reaction section. The steam generation unit is connected to the reaction section to provide water vapor.

2. The natural gas hydrogen production system according to claim 1, characterized in that: The hydrogen production unit further comprises a natural gas compressor and a raw gas buffer tank, and the natural gas source is sequentially connected to the natural gas compressor, the raw gas buffer tank and the convection section.

3. The natural gas hydrogen production system according to claim 2, characterized in that: The hydrogen production unit further comprises a cooler, which is connected to the outlet of the reaction section and is used for cooling the produced hydrogen.

4. The natural gas hydrogen production system according to claim 3, characterized in that: The hydrogen production unit further comprises a gas-liquid separator, which is connected to the outlet of the cooler and is used for separating water from the hydrogen.

5. The natural gas hydrogen production system according to claim 4, characterized in that: The hydrogen production unit also includes a PSA hydrogen extraction device, the inlet of the PSA hydrogen extraction device is connected to the outlet of the gas-liquid separator, the PSA hydrogen extraction device has a hydrogen outlet and a miscellaneous gas outlet, the hydrogen outlet is used to discharge the produced hydrogen, and the miscellaneous gas outlet is connected to the heating part to burn the miscellaneous gas.

6. The natural gas hydrogen production system according to claim 5, characterized in that: The hydrogen outlet is also connected to the raw gas buffer tank for introducing part of the hydrogen into the raw gas buffer tank.

7. The natural gas hydrogen production system according to claim 1, characterized in that: The natural gas source is also connected to the heating part for inputting natural gas into the heating part for combustion.

8. The natural gas hydrogen production system according to claim 7, characterized in that: The hydrogen production unit further includes a fuel gas buffer tank, and the natural gas source is further connected to the heating part via the fuel gas buffer tank.

9. The natural gas hydrogen production system according to claim 1, characterized in that: The steam generation unit comprises a desalted water source and a steam generator, wherein the desalted water source is connected to the steam generator, and the steam generator is connected to the reaction section.

10. The natural gas hydrogen production system according to claim 9, characterized in that: The reformer also includes a superheater, the steam generator and the desulfurization tank are connected to the inlet of the superheater, the outlet of the superheater is connected to the reaction section, and the heating part also heats the superheater.

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