A method for producing high-purity hydrogen and by-product carbon dioxide by step-by-step conversion of carbon-containing energy using iron-containing mineral solid waste and generating electricity

Abstract

The present invention discloses a method for utilizing iron-containing mineral solid waste to perform step-by-step conversion of carbon-containing energy to prepare high-purity hydrogen and by-product carbon dioxide and generate electricity. The method comprises the following steps: using air as an oxygen source, water as a hydrogen source, carbon-containing energy as input energy, and iron-containing solid waste as a circulating solid phase medium, obtaining a hydrogen-producing medium and by-producing pure carbon dioxide through the hierarchical step-by-step utilization of different reactive substances in the carbon-containing energy, and finally producing pure hydrogen through the hydrolysis reaction of the hydrogen-producing medium; completely oxidizing the hydrogen-producing product produced by the previous hydrolysis reaction with air and obtaining energy for power generation, thereby realizing the recycling and resource utilization of iron-containing mineral solid waste. The method proposed by the present invention realizes the efficient hierarchical conversion and energy cascade utilization of carbon-containing energy, the low-energy separation and preparation of pure hydrogen, and the by-product of pure carbon dioxide and electricity generation, establishes an efficient quality and energy conversion pathway, and improves the economy and cost-effectiveness of the overall process.

Description

Technical Field

[0001] The present invention relates to the fields of energy and environmental protection, and in particular to a method for utilizing iron-containing mineral solid waste to perform step-by-step conversion of carbon-containing energy to prepare high-purity hydrogen and by-product carbon dioxide and generate electricity. Background Art

[0002] The large-scale use of carbon-containing energy leads to massive emissions of environmental pollutants and greenhouse gases such as carbon dioxide, significantly impacting the environment and the deterioration of the global climate. Achieving low-energy capture of carbon dioxide as a product during carbon-containing energy utilization and transitioning to hydrogen energy is of great significance and a crucial means for the clean, efficient, and sustainable use of carbon-containing energy. Hydrogen is a clean energy source with a high calorific value, producing only water and no greenhouse gases. Hydrogen is an important basic raw material for the chemical and electronics industries, with widespread applications in ammonia synthesis, petroleum refining, petrochemical products, and electronics processing. Carbon dioxide is also a key chemical raw material. Hydrogen production from fossil fuels involves numerous technical routes, with thermochemical and electrochemical methods being the most typical. Electrochemical methods are hampered by low fossil energy generation efficiency (fossil energy to electricity) and electrochemical conversion efficiency (electricity to hydrogen), namely, limitations imposed by the Carnot cycle and the material's quantum electron transfer efficiency, putting them at a disadvantage. The conventional thermochemical route involves methane reforming / gasification to produce synthesis gas, but the subsequent separation of synthesis gas (H2 / CO / CH4 / CO2) is energy-intensive, and the purity of the hydrogen product is difficult to guarantee, limiting its application areas. In short, the common challenges of current clean hydrogen production technologies are low energy efficiency, high carbon emissions, and significant energy consumption.

[0003] At the same time, the safe and economic disposal of bulk mineral solid waste faces significant challenges. Factors such as declining ore grades and accumulated output over the years have resulted in a massive stockpile of mineral solid waste, with significant annual growth. However, methods and approaches for its utilization are limited and inefficient. For example, bauxite residues, such as red mud, produced during alumina extraction in the aluminum industry, currently exceed 100 million tons annually in my country alone, with a cumulative total of 1.1 billion tons. This vast amount of red mud is not fully and effectively utilized, relying solely on large-scale storage yards. This not only occupies land but also causes severe environmental pollution and wastes the high-value iron resources contained in the red mud. Similar challenges exist for discarded steel slag and iron-depleted solid waste from the steel industry. In the context of the "dual carbon" initiative, there is a need to find ways to scale, recycle, and repurpose iron-containing solid wastes that are commensurate with large production capacity. Summary of the Invention

[0004] The present invention aims to provide a method for producing high-purity hydrogen and byproduct carbon dioxide through the stepwise conversion of carbon-containing energy using iron-containing mineral solid waste, and generating electricity. The proposed method achieves efficient, hierarchical conversion of carbon-containing energy and cascaded energy utilization, efficient product separation with low energy consumption, and the low-energy separation and production of pure carbon dioxide and pure hydrogen. This establishes a highly efficient quality and energy conversion pathway, improving the economics and cost-effectiveness of the overall process.

[0005] The present invention is achieved through the following technical solutions:

[0006] A method for utilizing iron-containing mineral solid waste to perform step-by-step conversion of carbon-containing energy to prepare high-purity hydrogen and by-product carbon dioxide and generate electricity, comprising the following steps: using air as an oxygen source, water as a hydrogen source, carbon-containing energy as input energy, and iron-containing mineral solid waste as a circulating solid phase medium, the method obtains a hydrogen production precursor and produces pure carbon dioxide as a by-product through the hierarchical and step-by-step utilization of different reactive substances in the carbon-containing energy, and finally produces pure hydrogen through the hydrolysis reaction of the hydrogen production precursor; and completely oxidizing the hydrogen production product produced by the previous hydrolysis reaction with air to obtain energy for power generation, thereby realizing the recycling and resource utilization of the iron-containing mineral solid waste.

[0007] The method proposed in the present invention is committed to solving the problems of high pollution, carbon emissions and low efficiency in the process of carbon-containing energy utilization. Based on the strategy of efficient hierarchical conversion and energy cascade utilization of carbon-containing energy, a technical framework for low-energy separation and preparation of pure hydrogen and by-product pure carbon dioxide is constructed, and an efficient quality and energy conversion pathway is established, thereby improving the economy and cost-effectiveness of the overall process, promoting the low-carbon, clean, efficient and sustainable utilization of carbon-containing energy, and having high scientific and technological value, social significance and environmental protection function.

[0008] Preferably, the method comprises the following steps:

[0009] (1) Gradual utilization of carbon-containing energy and mineral solid waste and efficient coupling of processes: the carbon-containing energy is first subjected to a pyrolysis reaction to obtain low-activity solid coke and high-activity gas, and then the iron-containing mineral solid waste and the low-activity solid coke are reacted in an initial reduction reactor with first water vapor and carbon dioxide as the reaction atmosphere to obtain a mixture of carbon dioxide and water vapor, and an initial reduction product (mineral solid waste in a suboxidized state), and then the initial reduction product and the high-activity gas are reacted in a deep reduction reactor to obtain a hydrogen production precursor and a mixture of carbon dioxide and water vapor, thereby achieving complete conversion of the low-activity solid coke and efficient utilization of the high-activity gas, and the mixture of carbon dioxide and water vapor is condensed to produce pure carbon dioxide as a by-product, and the condensed water vapor is recycled to participate in the reaction of the initial reduction reactor in step (1);

[0010] (2) Hydrogen production by hydrolysis of a solid waste-based hydrogen production medium: the hydrogen production precursor and the second water vapor obtained in step (1) are introduced into a hydrolysis hydrogen production reactor, and a mixture of hydrogen and water vapor and a suboxidized hydrogen production product are obtained after the reaction. After gas-solid separation, a gaseous mixture of hydrogen and water vapor is obtained, and then pure hydrogen is prepared after condensation. The condensed water vapor is recycled to participate in the reaction of the hydrolysis hydrogen production reactor in step (2);

[0011] (3) Air oxidation regeneration of hydrogen production products: The suboxidized hydrogen production products obtained in step (2) are introduced into an air regeneration reactor to react with the atmosphere in the air regeneration reactor to obtain completely oxidized regenerated mineral solid waste and obtain energy for power generation, thereby realizing the recycling and resource utilization of mineral solid waste. The regenerated mineral solid waste is recycled to participate in the reaction of the initial reduction reactor in step (1).

[0012] The heat source for the pyrolysis reaction in step (1) can be the flue gas or ash emitted during any of the reaction processes of steps (1) to (3). The pyrolysis products are low-activity solid char (pyrolysis solid phase product) and high-activity gas (pyrolysis gas). The former is solid char mainly composed of carbon elements, and the latter is combustible gases such as carbon monoxide, hydrogen, and methane. The pyrolysis reaction temperature is 450°C-950°C.

[0013] In step (1), a strategy of hierarchical utilization of carbon-containing energy and efficient coupling of its reactivity with mineral solid waste is adopted. In the initial reduction reactor, low-activity solid coke produced by the carbon-containing energy reacts with high-activity mineral solid waste to produce pure carbon dioxide as a by-product. The low-activity reduced mineral solid waste produced further reacts with high-activity gas produced by the carbon-containing energy in the deep reduction reactor to obtain a hydrogen production medium (hydrogen production precursor). The tail gas containing carbon dioxide and water vapor produced in the process can continue to be introduced into the initial reduction reactor in step (1) to participate in the reaction.

[0014] The low-energy separation and preparation process proposed in this invention avoids complex hydrogen production, purification, conversion, and separation reaction steps. By utilizing moderate temperatures, enhanced reaction kinetics, and rational temperature coordination, the process avoids the need for specialized equipment and materials. The product-side carbon dioxide is easily purified, and pollutant concentration is easily economically controlled. Water and hydrogen are easily separated, and pure carbon dioxide and high-grade thermal energy are also obtained during the process. The entire process achieves efficient hierarchical conversion and cascaded energy utilization of carbon-containing energy, efficient and low-energy product separation, and the low-energy separation and preparation of pure carbon dioxide and pure hydrogen. This establishes a highly efficient quality and energy conversion pathway, improving the overall process's economics and cost-effectiveness.

[0015] The process route of the present invention is as follows: in a preliminary reduction reactor, low-activity solid coke produced by carbon-containing energy reacts with high-activity mineral solid waste to form suboxidized mineral solid waste and pure carbon dioxide; the low-activity suboxidized mineral solid waste produced further reacts with high-activity gas produced by carbon-containing energy in a deep reduction reactor to obtain a hydrogen-producing medium. The energy demand of the strongly endothermic reduction reaction can be supplied by the mineral solid waste that is fully oxidized and regenerated in the air regeneration reactor during the cyclic reaction process. No air is introduced during the reduction process, thereby avoiding the mixing of carbon dioxide and nitrogen, and the gaseous product after condensation is pure carbon dioxide. At the same time, the tail gas containing carbon dioxide and water vapor produced during the process can continue to be introduced into the initial reduction reactor in step (1) to participate in the reaction. The reaction of the hydrogen-producing medium with water vapor in the hydrolysis hydrogen production reactor is slightly exothermic, so the reaction is operated under relatively mild conditions, and this step can obtain a large amount of pure hydrogen product. The suboxidized hydrogen production product produced by the hydrolysis hydrogen production reactor is completely oxidized in the air regeneration reactor, releasing high-grade heat energy and coordinating the thermal balance of the entire system.

[0016] Preferably, the iron-containing mineral solid waste in step (1) is selected from one or more of aluminum red mud, low-grade iron ore and iron and steelmaking waste slag, the aluminum red mud refers to one of the red muds obtained by the aluminum Bayer process, soda lime sintering process, and Bayer-sintering combined process, or a mixture thereof, and the low-grade iron ore is natural lean iron ore and / or iron slag.

[0017] Preferably, the carbon-containing energy in step (1) is carbon-containing primary fossil energy, renewable biomass, carbon-containing solid waste, and post-processed products of the above three.

[0018] Preferably, the molar ratio of the iron-containing mineral solid waste to the low-activity solid coke in step (1) is 1:1-1:2, the temperature of the initial reduction reactor is 600°C-1300°C, the reaction time is 4-30 min, the molar ratio of carbon dioxide to the first water vapor is 1:0.25-1:2.5, the temperature of the deep reduction reactor is 600°C-1300°C, the molar ratio of the initial reduction product to the high-activity gas is 10:1-1:1, and the reaction time is 4-30 min.

[0019] Further preferably, the molar ratio of the iron-containing mineral solid waste to the low-activity solid coke in step (1) is 1:1-1:2, the temperature of the initial reduction reactor is 900°C-1100°C, the reaction time is 8-10 min, the molar ratio of carbon dioxide to the first water vapor is 1:0.25-1:2.5, the temperature of the deep reduction reactor is 900°C-1000°C, the molar ratio of the initial reduction product to the high-activity gas is 10:1-1:1, and the reaction time is 4-20 min.

[0020] Preferably, the temperature of the hydrolysis hydrogen production reactor in step (2) is 600° C.-1300° C., and the molar ratio of the hydrogen production precursor to the second water vapor is 1:1-1:2.5.

[0021] Further preferably, the temperature of the hydrolysis hydrogen production reactor in step (2) is 900° C.-1000° C., and the molar ratio of the hydrogen production precursor to the second water vapor is 1:1.5-1:2.5.

[0022] Preferably, the temperature of the air regeneration reactor in step (3) is 600° C.-1200° C., and the atmosphere is air or oxygen-depleted air. The oxygen-depleted air refers to the exhaust gas from the air regeneration reactor.

[0023] Compared with existing technologies, the present invention offers the following advantages: The proposed method avoids complex hydrogen production, purification, conversion, and separation reaction steps; By utilizing moderate temperatures, enhanced reaction kinetics, and reasonable temperature coordination, it avoids the need for specialized equipment and materials; carbon dioxide can be easily purified at the product end, and pollutant concentration can be easily and economically controlled; water-hydrogen separation is extremely easy, and pure carbon dioxide and high-grade thermal energy can be obtained during the process. The entire process achieves efficient hierarchical conversion and cascaded energy utilization of carbon-containing energy, efficient product separation with low energy consumption, and the low-energy separation and preparation of pure carbon dioxide and pure hydrogen, establishing a highly efficient quality and energy conversion pathway and improving the overall process's economic efficiency and cost-effectiveness. DETAILED DESCRIPTION

[0024] The present invention will be described in further detail below with reference to the examples. These examples are intended to illustrate the present invention only and are not intended to limit the scope of the present invention. Experimental methods in the following examples, where specific conditions are not specified, generally follow conventional conditions in the art or conditions recommended by the manufacturer; raw materials and reagents used, unless otherwise specified, are considered to be commercially available through conventional markets.

[0025] Example 1

[0026] A method for utilizing iron-containing mineral solid waste to convert carbon-containing energy into high-purity hydrogen and by-product carbon dioxide and generate electricity, comprising the following steps:

[0027] (1) Gradual utilization and efficient coupling of carbon-containing energy and iron-containing mineral solid waste: Coal is used as carbon-containing fuel, and pyrolysis reaction is carried out at 600℃ to obtain low-activity coal char and high-activity coal pyrolysis gas. In the initial reduction reactor, with first water vapor and carbon dioxide as the reaction atmosphere, the temperature is 1000℃, and the molar ratio of carbon dioxide and water vapor is 1:2. The low-activity coal char reacts with mineral solid waste red mud for a residence time of 20 minutes to obtain solid phase products (initial reduction products) and gas phase products. The gas phase products are condensed to obtain pure carbon dioxide. The solid phase products are further reacted with high-activity coal pyrolysis gas in a deep reduction reactor at a temperature of 950℃ and a residence time of 10 minutes to obtain hydrogen production medium (hydrogen production precursor).

[0028] (2) Hydrolysis of solid waste-based hydrogen production medium to produce hydrogen: The hydrogen production medium obtained in step (1) and water vapor are introduced into a hydrolysis hydrogen production reactor at a temperature of 950°C. The molar ratio of the hydrogen production medium to water vapor is 1:1.5. After the reaction, a mixture of hydrogen and water vapor and a reduced hydrogen production product (suboxidized hydrogen production product) are obtained. After gas-solid separation, a gaseous mixture of hydrogen and water vapor is obtained, which is then condensed to obtain a pure hydrogen product.

[0029] (3) Air oxidation regeneration of hydrogen production products: The reduced hydrogen production products obtained in step (2) enter the air regeneration reactor and react with the air in the reactor at a temperature of 1000°C to obtain completely oxidized and regenerated mineral solid waste and obtain high-grade thermal energy and generate electricity.

[0030] (4) Starting from the completely oxidized and regenerated mineral solid waste, the above steps (1) to (3) are repeated to obtain the same product as above.

[0031] In this embodiment, it was measured that the carbon capture rate was 99%, the carbon dioxide purity was 99%, and the hydrogen purity was 99%.

[0032] Example 2

[0033] Same as Example 1, except that:

[0034] In step (1), the temperature of the initial reduction reactor is 950° C., the molar ratio of carbon dioxide to water vapor is 1:1.5, and the residence time is 30 min. The temperature of the deep reduction reactor is 900° C., and the residence time is 20 min. In step (2), the temperature of the hydrolysis hydrogen production reactor is 900° C., and the molar ratio of the hydrogen production medium to water vapor is 1:2.5.

[0035] In this embodiment, it was measured that the carbon capture rate was 98%, the carbon dioxide purity was 97%, and the hydrogen purity was 92%.

[0036] Example 3

[0037] Same as Example 1, except that:

[0038] In step (1), the carbon-containing fuel is biomass, the biomass is sawdust, the temperature of the initial reduction reactor is 950°C, the molar ratio of carbon dioxide and water vapor is 1:1, and the residence time is 8 minutes. The temperature of the deep reduction reactor is 900°C, and the residence time is 4 minutes. In step (2), the temperature of the hydrolysis hydrogen production reactor is 900°C, and the molar ratio of the hydrogen production precursor and water vapor is 1:1.25.

[0039] In this embodiment, it was measured that the carbon capture rate was 99%, the carbon dioxide purity was 96%, and the hydrogen purity was 99%.

[0040] Example 4

[0041] Same as Example 1, except that:

[0042] The carbon-containing fuel is biomass, which is sawdust. In step (1), the temperature of the initial reduction reactor is 900°C, the molar ratio of carbon dioxide to water vapor is 1:0.25, and the residence time is 25 minutes. The temperature of the deep reduction reactor is 900°C, and the residence time is 15 minutes. In step (2), the temperature of the hydrolysis hydrogen production reactor is 1000°C, and the molar ratio of the hydrogen production precursor to water vapor is 1:2.

[0043] In this embodiment, it was measured that the carbon capture rate was 96%, the carbon dioxide purity was 97%, and the hydrogen purity was 98%.

[0044] Example 5

[0045] Same as Example 1, except that:

[0046] The mineral solid waste is lean iron ore. In step (1), the temperature of the initial reduction reactor is 1100° C., the molar ratio of carbon dioxide to water vapor is 1:2.5, and the residence time is 30 minutes. The temperature of the deep reduction reactor is 1000° C., and the residence time is 20 minutes. In step (2), the temperature of the hydrolysis hydrogen production reactor is 1000° C., and the molar ratio of the hydrogen production precursor to water vapor is 1:2.5.

[0047] In this embodiment, it was measured that the carbon capture rate was 95%, the carbon dioxide purity was 95%, and the hydrogen purity was 98%.

[0048] The description of the above embodiments is only used to help understand the technical solution and core ideas of the present invention. It should be pointed out that for those skilled in the art, several improvements and modifications can be made to the present invention without departing from the principles of the present invention. These improvements and modifications also fall within the scope of protection of the claims of the present invention.

Claims

1. A method for producing high-purity hydrogen and by-product carbon dioxide and generating electricity by using iron-containing mineral solid waste to convert carbon-containing energy into stepwise conversion, characterized in that: The specific steps include: (1) Gradual utilization of carbon-containing energy and mineral solid waste and efficient coupling of processes: the carbon-containing energy is first subjected to pyrolysis reaction to obtain low-activity solid coke and high-activity gas, and then the iron-containing mineral solid waste and the low-activity solid coke are reacted in an initial reduction reactor with first water vapor and carbon dioxide as the reaction atmosphere to obtain a mixture of carbon dioxide and water vapor, and an initial reduction product, and then the initial reduction product and the high-activity gas are reacted in a deep reduction reactor to obtain a hydrogen production precursor and a mixture of carbon dioxide and water vapor, thereby achieving complete conversion of low-activity solid coke and efficient utilization of high-activity gas, and the mixture of carbon dioxide and water vapor is condensed to produce pure carbon dioxide as a by-product, and the condensed water vapor is recycled to participate in the reaction of the initial reduction reactor in step (1); (2) Hydrogen production by hydrolysis of solid waste-based hydrogen production medium: the hydrogen production precursor and the second water vapor obtained in step (1) are introduced into a hydrolysis hydrogen production reactor, and a mixture of hydrogen and water vapor and a suboxidation state hydrogen production product are obtained after the reaction. After gas-solid separation, a gaseous mixture of hydrogen and water vapor is obtained, and then pure hydrogen is prepared after condensation. The condensed water vapor is recycled to participate in the reaction of the hydrolysis hydrogen production reactor in step (2); (3) Air oxidation regeneration of hydrogen production products: The suboxidized hydrogen production products obtained in step (2) are introduced into an air regeneration reactor to react with the atmosphere in the air regeneration reactor to obtain completely oxidized regenerated mineral solid waste and obtain energy for power generation, thereby realizing the recycling and resource utilization of mineral solid waste. The regenerated mineral solid waste is recycled to participate in the reaction of the initial reduction reactor in step (1).

2. The method according to claim 1, characterized in that The iron-containing mineral solid waste in step (1) is selected from one or more of aluminum red mud, low-grade iron ore and iron and steelmaking waste slag. The aluminum red mud refers to one of the red muds obtained by the aluminum Bayer process, soda lime sintering process, and Bayer-sintering combined process, or a mixture thereof. The low-grade iron ore is natural lean iron ore and / or iron slag.

3. The method according to claim 1, characterized in that The carbon-containing energy in step (1) is carbon-containing primary fossil energy, renewable biomass, carbon-containing solid waste, and post-processed products of the above three.

4. The method according to claim 1, wherein The molar ratio of the iron-containing mineral solid waste to the low-activity solid coke in step (1) is 1:1-1:2, the temperature of the initial reduction reactor is 600°C-1300°C, the reaction time is 4-30 min, the molar ratio of carbon dioxide to the first water vapor is 1:0.25-1:2.5, the temperature of the deep reduction reactor is 600°C-1300°C, the molar ratio of the initial reduction product to the high-activity gas is 10:1-1:1, and the reaction time is 4-30 min.

5. The method according to claim 4, characterized in that The molar ratio of the iron-containing mineral solid waste to the low-activity solid coke in step (1) is 1:1-1:2, the temperature of the initial reduction reactor is 900°C-1100°C, the reaction time is 8-10 min, the molar ratio of carbon dioxide to the first water vapor is 1:0.25-1:2.5, the temperature of the deep reduction reactor is 900°C-1000°C, the molar ratio of the initial reduction product to the high-activity gas is 10:1-1:1, and the reaction time is 4-20 min.

6. The method according to claim 1, characterized in that The temperature of the hydrolysis hydrogen production reactor in step (2) is 600°C-1300°C, and the molar ratio of the hydrogen production precursor and the second water vapor is 1:1-1:2.

5.

7. The method according to claim 6, characterized in that The temperature of the hydrolysis hydrogen production reactor in step (2) is 900°C-1000°C, and the molar ratio of the hydrogen production precursor to the second water vapor is 1:1.5-1:2.

5.

8. The method according to claim 1, characterized in that The temperature of the air regeneration reactor in step (3) is 600°C-1200°C, and the atmosphere is air or oxygen-depleted air.