Method and system for directly producing hydrogen by using waste heat of gas power plant

Abstract

The invention discloses a method and a system for directly producing hydrogen by using waste heat of a gas power plant. The method comprises the following steps: S1, performing high-temperature hydrolysis reaction on calcium bromide and / or magnesium chloride and water to obtain calcium oxide, magnesium oxide, hydrogen chloride and hydrogen bromide; s2, carrying out chlorination reaction on calcium oxide, magnesium oxide and mixed gas of chlorine gas and bromine gas to obtain calcium bromide and magnesium chloride which are used as part of reaction raw materials in S1; s3, ferric oxide reacts with the mixture of hydrogen chloride and hydrogen bromide obtained in the step S1, ferric chloride, ferric bromide, chlorine and bromine gas are obtained, and chlorine and bromine gas serve as part of reaction raw materials in the step S2; s4, the ferric chloride and the ferric bromide react with water, hydrogen is obtained, and byproducts are ferric oxide, hydrogen bromide and hydrogen chloride; the heat of each reaction in the steps S1 to S4 is from the waste heat of the gas power plant. The method has the advantages of low cracking hydrogen production reaction temperature, simple reaction process, low power consumption, high overall conversion efficiency of the system and the like, so that the economical efficiency and the application scene of direct water cracking hydrogen production are improved.

Description

Technical Field

[0001] This invention relates to a method and system for directly producing hydrogen using waste heat from a gas-fired power plant. Background Technology

[0002] Hydrogen energy, as a clean and high-energy-density secondary energy source, is widely used in industry, metallurgy, transportation, and construction. Currently, the main sources of hydrogen include hydrogen production from fossil fuels, industrial by-product hydrogen, and water electrolysis. However, hydrogen production from fossil fuels and industrial by-products often generates significant amounts of impurities (CO, sulfides, chlorides, etc.), resulting in low hydrogen purity and requiring subsequent purification processes. Water electrolysis, which utilizes renewable energy sources such as photovoltaics and wind power coupled with water electrolysis to produce green hydrogen, offers advantages such as high hydrogen purity, low carbon emissions, and environmental friendliness, and is gradually becoming the mainstream hydrogen production method in the future.

[0003] Current hydrogen production methods suffer from the following drawbacks: direct water cracking requires high temperatures (approximately 2000℃), photocatalytic cracking has low reaction efficiency, and water electrolysis consumes a large amount of electricity. Therefore, this invention provides a novel water cracking hydrogen production technology. Summary of the Invention

[0004] The purpose of this invention is to provide a novel water cracking hydrogen production technology. Utilizing high-temperature steam generated during gas-fired power plants and nuclear power generation, and through a newly developed water cracking hydrogen production intermediate and a cyclic reaction process, it achieves water cracking hydrogen production under intermediate-temperature conditions, significantly reducing the water cracking hydrogen production temperature compared to direct water cracking technology. This invention offers advantages such as low reaction temperature, simple reaction process, low power consumption, and high overall system conversion efficiency, thereby improving the economics and application scenarios of direct water cracking hydrogen production.

[0005] The present invention provides a method for direct hydrogen production using waste heat from gas-fired power plants, which achieves hydrogen production at temperatures below 1000°C using a chemical-thermal decomposition coupling method, comprising the following steps:

[0006] S1, calcium bromide and / or magnesium chloride react with water at high temperature to produce calcium oxide, magnesium oxide, hydrogen chloride and hydrogen bromide;

[0007] S2. The calcium oxide and magnesium oxide are reacted with a mixture of chlorine and bromine gas to produce calcium bromide and magnesium chloride, which are used as part of the reaction raw materials in step S1.

[0008] S3. Iron oxide reacts with the mixture of hydrogen chloride and hydrogen bromide obtained in step S1 to obtain iron chloride, iron bromide, chlorine and bromine. The chlorine and bromine are used as part of the reaction raw materials in step S2.

[0009] S4. The ferric chloride and the ferric bromide react with water to produce hydrogen gas, and the byproducts are ferric oxide, hydrogen bromide and hydrogen chloride.

[0010] The heat generated by each reaction in steps S1-S4 comes from the waste heat of the gas-fired power plant.

[0011] Specifically, the waste heat from the gas-fired power plant can be recovered through a waste heat recovery system and then fed into each reaction unit. The waste heat recovery system includes a heat exchanger and a waste heat boiler, utilizing a circulating water system to absorb heat. The waste heat boiler uses the high-temperature exhaust gas from the gas-fired power plant to heat water. Part of the high-temperature steam is used as raw material in steps S1 and S4 to participate in the reaction, and part is used as a heat exchange medium to provide heat for each reaction. The heat exchange capacity is designed according to the reaction temperature, and the outlet gas temperature is controlled by adjusting the circulating water flow rate.

[0012] In the method of the present invention, in step S1, the temperature of the high-temperature hydrolysis reaction is 600-1000℃;

[0013] The mass ratio of magnesium chloride to calcium bromide is 1:1 to 1:6.

[0014] In the method of the present invention, in step S2, the temperature of the chlorination reaction is 500-700°C;

[0015] The volume ratio of chlorine to bromine is 1:1 to 1:6.

[0016] In the method of the present invention, in step S3, the reaction temperature is 150–500°C;

[0017] The volume ratio of hydrogen chloride to hydrogen bromide is 1:1 to 1:6.

[0018] In the method of the present invention, in step S4, the temperature of the reaction is 500-700°C.

[0019] The present invention further provides a system for directly producing hydrogen using waste heat from a gas-fired power plant, comprising a high-temperature hydrolysis reaction unit, a chlorination reaction unit, a chlorine and bromine gas preparation unit, and a hydrogen gas preparation unit;

[0020] The gas outlet of the high-temperature hydrolysis reaction unit is connected to the raw material inlet of the chlorine and bromine preparation unit, and the solid outlet is connected to the raw material inlet of the chlorination reaction unit.

[0021] The product outlet of the chlorination reaction unit is connected to the raw material inlet of the high-temperature hydrolysis reaction unit.

[0022] The gas outlet of the chlorine and bromine preparation unit is connected to the raw material inlet of the chlorination reaction unit, and the solid outlet is connected to the raw material inlet of the hydrogen preparation unit.

[0023] The by-product outlet of the hydrogen preparation unit is connected to the raw material inlet of the chlorine and bromine preparation unit.

[0024] The heat from the high-temperature hydrolysis reaction unit, the chlorination reaction unit, the chlorine and bromine gas preparation unit, and the hydrogen gas preparation unit comes from the waste heat of the gas-fired power plant.

[0025] The present invention has the following beneficial technical effects:

[0026] 1. The novel water cracking hydrogen production technology provided by this invention utilizes high-temperature steam generated during gas-fired power plants and nuclear power generation. Through a newly developed water cracking hydrogen production intermediate and a cyclic reaction process, it achieves water cracking hydrogen production under intermediate temperature conditions, significantly reducing the water cracking hydrogen production temperature compared to direct water cracking technology. This technology has advantages such as low reaction temperature, simple reaction process, low power consumption, and high overall system conversion efficiency, thereby improving the economics and application scenarios of direct water cracking hydrogen production.

[0027] 2. The method for producing hydrogen using surplus heat from gas-fired power plants provided by this invention employs four reaction units, with the product of each reaction unit serving as the raw material for another reaction unit. Through this design, only heat energy and water are consumed in the entire reaction system to produce hydrogen and oxygen, realizing a new method for producing hydrogen from the heat energy of gas-fired power plants.

[0028] 3. Compared with traditional direct water cracking hydrogen production technology, this invention significantly reduces the reaction temperature; compared with photocatalyst cracking hydrogen production technology, it improves the system reaction efficiency; compared with water electrolysis hydrogen production technology, this invention does not consume electrical energy and has strong inventiveness. Attached Figure Description

[0029] Figure 1 This is a schematic diagram of the hydrogen production system that utilizes waste heat from a gas-fired power plant according to the present invention. Detailed Implementation

[0030] Unless otherwise specified, the experimental methods used in the following examples are conventional methods.

[0031] Unless otherwise specified, all materials and reagents used in the following examples are commercially available.

[0032] Example 1

[0033] exist Figure 1 Hydrogen is produced in the system shown.

[0034] (1) High-temperature hydrolysis reaction unit: Calcium bromide and magnesium chloride are mixed at a mass ratio of 2:1 at 800℃ and subjected to high-temperature hydrolysis reaction to obtain calcium oxide, magnesium oxide, hydrogen chloride and hydrogen bromide.

[0035] (2) Chlorination reaction unit: The calcium oxide and magnesium oxide prepared in step 1 are subjected to chlorination reaction with a mixture of chlorine and bromine at 700°C to prepare magnesium chloride and calcium bromide, which are then fed into the high-temperature hydrolysis reaction unit as raw materials.

[0036] (3) Chlorine and bromine preparation unit: At 500°C, iron oxide is reacted with the mixture of hydrogen chloride and hydrogen bromide prepared in step 1 to prepare ferric chloride and ferric bromide, as well as a mixture of chlorine and bromine, which are used as raw materials for the chlorination reaction unit.

[0037] (4) Hydrogen production unit: At 700℃, the prepared ferric chloride and ferric bromide are reacted with water to produce hydrogen, with ferric oxide, hydrogen bromide and hydrogen chloride as byproducts;

[0038] The heat generated in each step of the reaction comes from waste heat from the gas-fired power plant.

[0039] Example 2

[0040] exist Figure 1 Hydrogen is produced in the system shown.

[0041] (1) High-temperature hydrolysis reaction unit: Calcium bromide is hydrolyzed with water at 600℃ to obtain calcium oxide and hydrogen bromide;

[0042] (2) Chlorination reaction unit: The calcium oxide prepared in step 1 is chlorinated with bromine gas at 500°C to prepare calcium bromide, which is then fed into the high-temperature hydrolysis reaction unit as raw material.

[0043] (3) Chlorine and bromine preparation unit: At 400°C, iron oxide is reacted with the hydrogen bromide mixture prepared in step 1 to prepare iron bromide and bromine, which are used as raw materials for the chlorination reaction unit.

[0044] (4) Hydrogen production unit: At 600℃, the prepared ferric bromide is reacted with water to produce hydrogen, with ferric oxide and hydrogen bromide as byproducts.

[0045] Example 3

[0046] exist Figure 1 Hydrogen is produced in the system shown.

[0047] (1) High-temperature hydrolysis reaction unit: Magnesium chloride and water are subjected to high-temperature hydrolysis reaction at 700℃ to obtain magnesium oxide and hydrogen chloride;

[0048] (2) Chlorination reaction unit: The magnesium oxide prepared in step 1 is chlorinated with chlorine at 600°C to prepare magnesium chloride, which is then fed into the high-temperature hydrolysis reaction unit as raw material.

[0049] (3) Chlorine preparation unit: At 300°C, iron oxide is reacted with hydrogen chloride prepared in step 1 to prepare ferric chloride and chlorine, which are used as raw materials for the chlorination reaction unit.

[0050] (4) Hydrogen production unit: At 650°C, the prepared ferric chloride is reacted with water to produce hydrogen, with ferric oxide and hydrogen chloride as byproducts.

Claims

1. A method for directly producing hydrogen using waste heat from a gas-fired power plant, comprising the following steps: S1, calcium bromide and / or magnesium chloride react with water at high temperature to produce calcium oxide, magnesium oxide, hydrogen chloride and hydrogen bromide; S2. The calcium oxide and magnesium oxide are reacted with a mixture of chlorine and bromine gas to produce calcium bromide and magnesium chloride, which are used as part of the reaction raw materials in step S1. S3. Iron oxide reacts with the mixture of hydrogen chloride and hydrogen bromide obtained in step S1 to obtain iron chloride, iron bromide, chlorine and bromine. The chlorine and bromine are used as part of the reaction raw materials in step S2. S4. The ferric chloride and the ferric bromide react with water to produce hydrogen gas, and the byproducts are ferric oxide, hydrogen bromide and hydrogen chloride. The heat generated by each reaction in steps S1-S4 comes from the waste heat of the gas-fired power plant.

2. The method according to claim 1, characterized in that: In step S1, the temperature of the high-temperature hydrolysis reaction is 600–1000°C; The mass ratio of magnesium chloride to calcium bromide is 1:1 to 1:

6.

3. The method according to claim 1 or 2, characterized in that: In step S2, the temperature of the chlorination reaction is 500–700°C; The volume ratio of chlorine to bromine is 1:1 to 1:

6.

4. The method according to any one of claims 1-3, characterized in that: In step S3, the reaction temperature is 150–500°C; The volume ratio of hydrogen chloride to hydrogen bromide is 1:1 to 1:

6.

5. The method according to any one of claims 1-4, characterized in that: In step S4, the reaction temperature is 500–700°C.

6. A system for directly producing hydrogen using waste heat from a gas-fired power plant, comprising a high-temperature hydrolysis reaction unit, a chlorination reaction unit, a chlorine and bromine gas preparation unit, and a hydrogen gas preparation unit; The gas outlet of the high-temperature hydrolysis reaction unit is connected to the raw material inlet of the chlorine and bromine preparation unit, and the solid outlet is connected to the raw material inlet of the chlorination reaction unit. The product outlet of the chlorination reaction unit is connected to the raw material inlet of the high-temperature hydrolysis reaction unit. The gas outlet of the chlorine and bromine preparation unit is connected to the raw material inlet of the chlorination reaction unit, and the solid outlet is connected to the raw material inlet of the hydrogen preparation unit. The by-product outlet of the hydrogen preparation unit is connected to the raw material inlet of the chlorine and bromine preparation unit. The heat from the high-temperature hydrolysis reaction unit, the chlorination reaction unit, the chlorine and bromine gas preparation unit, and the hydrogen gas preparation unit comes from the waste heat of the gas-fired power plant.

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