阅读说明：本技术 一种利用甲烷和水为原料生产氢气的方法 (method for producing hydrogen by using methane and water as raw materials ) 是由 郝海刚 曹成 宫聚辉 崔林霞 孙瑞琴 石可 卢珂 张铭元 闫哲 胡明浩 高瑞 于 2019-09-30 设计创作，主要内容包括：本发明公开了一种利用甲烷和水为原料生产氢气的方法。本发明创造性地将三氧化二铁作为循环反应物料,巧妙的利用铁物相之间相互转换的化学反应生产氢气。首先将氧化铁用氢气还原为纯铁,然后利用铁与甲烷反应发生碳化反应,生成碳化铁和氢气,最后再利用碳化铁和水发生氧化反应生成氧化铁、二氧化碳和氢气。虽然氧化铁转变为纯铁的过程中消耗了一部分氢气,但是在纯铁被甲烷碳化和碳化铁被水氧化的过程中产生了更多的氢气,因此本发明最终实现了以甲烷和水为原料制备氢的目的。上述方法的设备和原料的投资小,能量利用效率和原料利用效率都明显优于煤炭制氢技术和天然气重整制氢技术,更适合大规模的推广使用。(The invention discloses a method for producing hydrogen by using methane and water as raw materials. The invention creatively takes the ferric oxide as the circulating reaction material and skillfully utilizes the chemical reaction of mutual conversion between iron phases to produce the hydrogen. Firstly, reducing iron oxide into pure iron by using hydrogen, then utilizing the reaction of iron and methane to produce carbonization reaction to produce iron carbide and hydrogen, and finally utilizing iron carbide and water to produce oxidation reaction to produce iron oxide, carbon dioxide and hydrogen. Although a part of hydrogen is consumed in the process of converting the iron oxide into the pure iron, more hydrogen is generated in the process of carbonizing the pure iron by the methane and oxidizing the iron carbide by the water, so that the invention finally achieves the purpose of preparing hydrogen by using the methane and the water as raw materials. The method has the advantages of small investment on equipment and raw materials, obviously superior energy utilization efficiency and raw material utilization efficiency to the coal hydrogen production technology and the natural gas reforming hydrogen production technology, and is more suitable for large-scale popularization and application.)

1. A method for producing hydrogen by using methane and water as raw materials is characterized in that water and methane are used as raw materials, ferric oxide is used as a circulating reaction material to produce hydrogen,

The method specifically comprises the following steps:

(1) Reduction of iron oxide to pure iron with hydrogen

uniformly filling iron oxide in a main reaction tower; introducing hydrogen into the bottom of the main reaction tower, and reacting with iron oxide in the main reaction tower at 100-700 ℃ to generate pure iron and water vapor;

Unreacted hydrogen and generated water vapor leave from the top of the main reaction tower and enter a gas separation device, the hydrogen is recycled, and the water vapor is cooled and stored for later use;

(2) The methane and the iron are carbonized to generate iron carbide and hydrogen

After the iron oxide in the main reaction tower is completely converted into pure iron, switching hydrogen into methane gas to enter from the bottom of the main reaction tower, and carrying out carbonization reaction with the pure iron at 300-800 ℃ to generate iron carbide and hydrogen;

Unreacted methane and generated hydrogen gas leave from the top of the main reaction tower and enter a gas separation device; the separated methane is recycled, and the hydrogen is purified and then sent to a hydrogen storage tank;

(3) The steam and the iron carbide are subjected to oxidation reaction to generate iron oxide, carbon dioxide and hydrogen

After pure iron in the main reaction tower is completely converted into iron carbide, methane gas is switched into water vapor and introduced from the bottom of the main reaction tower, and the water vapor reacts with the iron carbide at the temperature of 100-500 ℃ to generate iron oxide, carbon dioxide and hydrogen;

unreacted water vapor, generated hydrogen and carbon dioxide leave from the top of the main reaction tower and enter a gas separation device, the separated water vapor is recycled, and the separated hydrogen and carbon dioxide are respectively sent to corresponding storage tanks;

(4) At this point, one cycle of reaction is completed, and the next cycle of reaction is entered.

2. the method for producing hydrogen using methane and water as raw materials according to claim 1, wherein the main reaction tower is a fixed bed reactor or a fluidized bed reactor.

3. the method for producing hydrogen using methane and water as raw materials according to claim 1, wherein the gas separation device comprises a pressure swing adsorption, physical absorption, chemical absorption, cryogenic distillation, or membrane separation device.

4. A method for producing hydrogen from methane and water as raw materials according to claim 3, wherein the gas separation device is a separation device using a membrane separation method.

5. The method for producing hydrogen using methane and water as raw materials according to claim 1, wherein the reaction temperature in the step (1) is 300-500 ℃.

6. The method for producing hydrogen using methane and water as raw materials according to claim 1, wherein the reaction temperature in the step (2) is 400 to 500 ℃.

7. The method for producing hydrogen using methane and water as raw materials according to claim 1, wherein the reaction temperature in the step (3) is 150 to 250 ℃.

8. A method for producing hydrogen using methane and water as raw materials according to any one of claims 1 to 7, wherein the reaction pressure of the steps (1), (2) and (3) is 0 to 0.5 MPa.

9. The method for producing hydrogen using methane and water as raw materials according to claim 8, wherein the reaction pressure of the steps (1), (2) and (3) is 0.1 Mpa.

Technical Field

The invention belongs to the technical field of hydrogen preparation and production, and particularly relates to a technology for preparing hydrogen by taking methane and water as raw materials and iron oxide as a circulating reaction material.

Background

The hydrogen energy is a public and clean energy, is known as a secondary energy with the most development prospect in the 21 st century, has a high calorific value of 142 to 106J/kg and is about three times of that of gasoline, and is also called as energy currency. The hydrogen energy plays an important role in solving the problems of energy crisis, global warming, environmental pollution and the like, and becomes a strategic choice for optimizing the energy consumption structure and guaranteeing the national energy supply safety in China. It is predicted that oil refining, new energy automobiles, clean energy power generation, and the like will be the largest end markets for hydrogen energy utilization, wherein the amount of industrial hydrogen used in the global oil refining will account for 90% of the total amount of global industrial hydrogen consumption. As environmental fuel requirements become more stringent, refinery hydrofinishing will require more industrial hydrogen to produce low sulfur clean fuels, which will greatly stimulate a rapid increase in industrial hydrogen demand.

At present, industrial hydrogen production schemes are mainly divided into the following categories:

(1) hydrogen production by fossil fuel: hydrogen production by natural gas, hydrogen production by coal, and the like.

(2) Hydrogen production by hydrogen-rich gas: hydrogen production from tail gas in ammonia synthesis production, hydrogen production from hydrogen-rich gas recovered from oil refinery, hydrogen production from byproduct recovered from chlor-alkali plant, hydrogen recovery from coke oven gas, etc.

(3) Preparing hydrogen from methanol: the method comprises the steps of preparing hydrogen by methanol decomposition, preparing hydrogen by methanol steam reforming, preparing hydrogen by partial oxidation of methanol and preparing hydrogen by conversion of methanol.

(4) and (3) hydrolysis hydrogen production: water electrolysis, alkaline electrolysis, polyelectrolyte membrane electrolysis, high-temperature electrolysis, photoelectrolysis, biological photolysis and thermochemical hydrolysis.

(5) Biological hydrogen production: biomass is subjected to gasification and a microbial catalytic dehydrogenation method to produce hydrogen.

While there are many industrial hydrogen production schemes, the one that can really be used on a large scale is the production of hydrogen from fossil fuels. Although hydrogen production by hydrogen-rich gas and biological hydrogen production reasonably utilize resources, the hydrogen produced by the two methods has high impurity content and low purity, and cannot meet the requirements of downstream enterprises on the purity of the hydrogen. Only the water electrolysis hydrogen production technology is mature in the hydrolysis hydrogen production scheme, the equipment is simple, and the operation is reliable. However, the water electrolysis hydrogen production technology has not been greatly developed for many years, mainly because the technology consumes a large amount of electric energy, and the expensive electricity price makes the water electrolysis hydrogen production cost high and the competitiveness is not strong, so that the technology is only suitable for small-scale hydrogen production. The methanol hydrogen production technology is mature, and compared with natural gas hydrogen production and water electrolysis hydrogen production, the methanol hydrogen production investment is low, and the process conditions are mild. However, the methanol hydrogen production technology is only suitable for the medium and small scale hydrogen production requirements, because the raw material of industrial methanol is coal or natural gas, and the first step of methanol production also needs to convert the coal or natural gas into hydrogen and then synthesize the hydrogen into methanol. The essence of the hydrogen production from methanol is that methanol is used as a hydrogen storage medium, and hydrogen stored in the methanol is released through a hydrogen production from methanol scheme when needed. Therefore, the production of hydrogen from methanol is unreasonable in terms of energy utilization.

at present, the scheme capable of producing hydrogen on a large scale is coal hydrogen production and natural gas hydrogen production in the hydrogen production by fossil fuel. The hydrogen production from coal is mainly to produce hydrogen by coal gasification technology, but the synthesis gas is obtained by coal gasification technology, rather than pure hydrogen, and the high-purity hydrogen can be produced by subsequent transformation technology and purification technology. Therefore, the coal gasification technology has higher integration level, longer process flow, more complicated preparation process than natural gas hydrogen production, and higher cost of the obtained hydrogen. The natural gas hydrogen production technology mainly comprises methane Steam Reforming (SRM), a methane Partial Oxidation Method (POM), methane autothermal reforming (ATR) and an adiabatic hydrogen production process of methane direct decomposition. The disadvantages of the steam reforming reaction of methane are large energy consumption, high reaction conditions, half of the total production cost of fuel, large plant construction scale and high investment. The hydrogen production process by methane catalytic partial oxidation has not been put into production formally because the source of cheap oxygen is difficult to solve, the instability of the catalyst and the safety problem thereof are not solved. The methane autothermal reforming hydrogen production as a novel hydrogen production method is not suitable for large-scale production of factories due to low production capacity and high device investment. The adiabatic conversion of methane to hydrogen is a market shortage due to the production of large amounts of carbon deposits which cannot be fully utilized.

Disclosure of Invention

Aiming at the technical problems in the field, the invention discloses a method for producing hydrogen by using methane and water as raw materials. The invention creatively takes the ferric oxide as the circulating reaction material and skillfully utilizes the chemical reaction of mutual conversion between iron phases to produce the hydrogen. Firstly, reducing iron oxide into pure iron by using hydrogen, then utilizing iron and methane to react to generate carbonization reaction to generate iron carbide and hydrogen, and finally utilizing iron carbide and water to generate oxidation reaction to generate iron oxide, carbon dioxide and hydrogen. Although a part of hydrogen is consumed in the process of converting the iron oxide into the pure iron, more hydrogen is generated in the process of carbonizing the pure iron by the methane and oxidizing the iron carbide by the water, so that the invention finally achieves the purpose of preparing hydrogen by using the methane and the water as raw materials.

The technical scheme of the invention is as follows: a method for producing hydrogen by using methane and water as raw materials is characterized in that water and methane are used as raw materials, and ferric oxide is used as a circulating reaction material to produce hydrogen, and the method specifically comprises the following steps:

(1) Reduction of iron oxide to pure iron with hydrogen

Uniformly filling iron oxide in a main reaction tower; introducing hydrogen into the bottom of the main reaction tower, and reacting with iron oxide in the main reaction tower at 100-700 ℃ to generate pure iron and water vapor;

Unreacted hydrogen and generated water vapor leave from the top of the main reaction tower and enter a gas separation device, the hydrogen is recycled, and the water vapor is cooled and stored for later use;

(2) the methane and the iron are carbonized to generate iron carbide and hydrogen

After the iron oxide in the main reaction tower is completely converted into pure iron, switching hydrogen into methane gas to enter from the bottom of the main reaction tower, and carrying out carbonization reaction with the pure iron at 300-800 ℃ to generate iron carbide and hydrogen;

Unreacted methane gas and generated hydrogen gas leave from the top of the main reaction tower and enter a gas separation device; the separated methane is recycled, and the hydrogen is purified and then sent to a hydrogen storage tank;

(3) The steam and the iron carbide are subjected to oxidation reaction to generate iron oxide, carbon dioxide and hydrogen

After pure iron in the main reaction tower is completely converted into iron carbide, methane gas is switched into water vapor and introduced from the bottom of the main reaction tower, and the water vapor reacts with the iron carbide at the temperature of 100-500 ℃ to generate iron oxide, carbon dioxide and hydrogen;

unreacted steam, generated hydrogen and carbon dioxide leave from the top of the main reaction tower and enter a gas separation device, the separated steam is recycled, and the separated hydrogen and carbon dioxide are respectively sent to corresponding storage tanks.

(4) At this point, one cycle of reaction is completed, and the next cycle of reaction is entered.

The reaction equation is as follows:

3Fe₂O₃+9H₂→6Fe+9H₂O (1)

2CH₄+6Fe→2Fe₃C+4H₂ (2)

2Fe₃C+13H₂O→3Fe₂O₃+2CO₂+13H₂ (3)

The main reaction tower is a fixed bed reactor or a fluidized bed reactor, and the fixed bed reactor is preferably used.

The gas separation means may comprise Pressure Swing Adsorption (PSA), absorption (including physical and chemical absorption), cryogenic distillation, membrane separation, and preferably membrane separation. The purity of the hydrogen separated by the method can reach more than 99.99 percent.

The reaction temperature in the step (1) is preferably 300-500 ℃.

The reaction temperature in the step (2) is preferably 400-500 ℃.

The reaction temperature in the step (3) is preferably 150-250 ℃.

The reaction pressure range of the steps (1), (2) and (3) is 0-0.5MPa, and preferably 0.1 MPa.

the invention has the advantages that:

1. From the production device of the invention (as shown in figure 1), only 1 reaction tower, 3 gas separation devices and 2 gas storage tanks are needed, and the equipment investment is small. The coal hydrogen production technology has complex process flow, relates to a plurality of reaction devices such as air separation, gasification, purification, transformation, decarburization and the like, and has complex internal structure and high manufacturing cost. The cost of a single entrained flow gasifier is more than 1 billion yuan, and a considerable scale coal hydrogen production plant is built, so the total investment is at least several billion yuan. Although the technological process of the hydrogen production technology by reforming natural gas is simpler than that of the coal production technology, the method also relates to a plurality of reaction devices such as desulfurization, air separation, first-stage conversion, second-stage conversion, decarburization and the like. In addition, the hydrogen production technology by reforming natural gas also needs to use expensive catalysts, and the catalysts need to be replaced periodically after being deactivated. In terms of raw materials used in the invention, the iron oxide is taken as a circulating reaction material, and the hydrogen can be prepared only by taking methane and water as raw materials, so that the investment on equipment and raw materials is small, and the process is clean and environment-friendly; therefore, compared with the existing methane hydrogen production process, the process is more suitable for large-scale popularization and application.

2. From the production process conditions of the invention, the optimal reaction temperature is not more than 500 ℃, and the reaction pressure is normal pressure or close to normal pressure, so that the energy utilization efficiency of the invention is higher compared with the hydrogen production by coal and natural gas. The mainstream technology for preparing hydrogen from coal at present is an entrained flow bed gasification technology, the reaction temperature is as high as 1000 ℃, the pressure is more than 3MPa, the coal gasification is used for preparing synthesis gas, and in order to obtain high-purity hydrogen, the synthesis gas also needs to undergo gas purification, shift reaction and decarburization reaction. The hydrogen production reaction by natural gas steam reforming is a strong endothermic reaction, the temperature exceeds 800 ℃, the reaction pressure is more than 1.5MPa, the obtained synthesis gas is also synthetic gas, and in order to prepare high-purity hydrogen, the conversion reaction and the decarburization reaction are needed. The coal hydrogen production technology and the natural gas reforming hydrogen production technology both need to burn part of raw materials to provide heat for the reaction because of high reaction temperature. The reaction temperature of the invention is lower, the waste heat of the chemical plant can be completely utilized to provide heat for the reaction, and if the heat provided by the chemical plant does not reach the temperature required by the reaction, less methane is required to be combusted to provide heat for the reaction. In conclusion, the energy utilization efficiency and the raw material utilization efficiency of the invention are obviously superior to those of the coal hydrogen production technology and the natural gas reforming hydrogen production technology.

Drawings

FIG. 1 is a process flow diagram of the present invention.

Detailed Description