Method for preparing high-purity hydrogen and by-product carbon dioxide and generating power by utilizing iron-containing mineral solid waste to carry out stepped conversion on carbon-containing energy

Abstract

The invention discloses a method for preparing high-purity hydrogen and by-product carbon dioxide and generating power by utilizing iron-containing mineral solid waste to carry out stepped conversion on carbon-containing energy. The method comprises the following steps that air serves as an oxygen source, water serves as a hydrogen source, carbon-containing energy serves as input energy, iron-containing solid waste serves as a circulating solid-phase medium, a hydrogen production medium is obtained through graded stepped utilization of different reaction active substances in the carbon-containing energy, pure carbon dioxide is produced as a byproduct, and finally pure hydrogen is prepared through hydrolysis of the hydrogen production medium. The hydrogen production product generated by the previous-step hydrolysis reaction is completely oxidized by air, and energy is obtained for power generation, so that cyclic regeneration and resource utilization of the iron-containing mineral solid waste are realized. According to the method provided by the invention, efficient graded conversion and energy gradient utilization of carbon-containing energy, low-energy-consumption separation preparation of pure hydrogen and byproduct pure carbon dioxide and power generation are realized, an efficient mass and energy conversion way is established, and the economical efficiency and cost performance of the overall process are improved.

Description

Technical Field

[0001] The present invention relates to the field of energy and environmental protection, and in particular to a method for preparing high-purity hydrogen and by-product carbon dioxide and generating electricity by step-converting carbon-containing energy using iron-containing mineral solid waste. Background Art

[0002] The large-scale utilization of carbon-containing energy leads to the emission of large amounts of environmental pollutants and greenhouse gases such as carbon dioxide, which has a huge impact on the deterioration of the environment and global climate. The low-energy capture of carbon dioxide and the transition to hydrogen energy in the process of carbon-containing energy utilization are of great significance and important means for the clean, efficient and sustainable utilization of carbon-containing energy. Among them, hydrogen energy is a clean energy with high calorific value. The energy product is only water and does not produce greenhouse gases. Hydrogen is an important basic raw material for the chemical and electronic industries and is widely used in production fields such as synthetic ammonia, petroleum refining, petrochemical products and electronic processing. Carbon dioxide is also an important chemical raw material. Hydrogen production from fossil energy involves many technical routes, with thermochemical and electrochemical methods being the most typical. The electrochemical method is limited by the low efficiency of fossil energy power generation (fossil energy-electricity) and electrochemical conversion efficiency (electricity-hydrogen energy), that is, it is in an unfavorable position due to the limitations of the Carnot cycle and the quantum electron transfer efficiency of the material; the existing conventional route of the thermochemical method is methane reforming / gasification to produce synthesis gas, but the subsequent separation of synthesis gas (H 2 / CO / CH 4 / CO 2 ) is a high energy-consuming process, and the purity of hydrogen products is difficult to guarantee and the application areas of hydrogen products are limited. In short, the common problems of current clean hydrogen production technologies are low energy utilization efficiency, high carbon emissions and huge energy consumption.

[0003] At the same time, the safe and economic disposal of bulk mineral solid waste is now facing severe challenges. At present, factors such as the decline in the grade of raw ore and the cumulative output over the years have resulted in a huge stock of mineral solid waste with a considerable annual increase, while the means and methods of utilization are poor and the utilization efficiency is low. Taking the bauxite waste slag such as red mud discharged when the aluminum industry extracts alumina as an example, the annual output of red mud in my country alone has exceeded 100 million tons and the cumulative amount is as high as 1.1 billion tons. A large amount of red mud has not been fully and effectively utilized and can only be stacked in large areas of yards, which not only occupies land, but also causes serious pollution to the environment, and at the same time wastes the high-value iron resources in the red mud. The abandoned iron slag and lean iron ore solid waste of the steel industry are facing a similar situation as the aluminum industry. Under the background of "dual carbon", it is necessary to find large-scale, high-value and resource-based utilization of iron-containing mineral solid waste corresponding to large production capacity. Summary of the invention

[0004] The purpose of the present invention is to provide a method for preparing high-purity hydrogen and by-product carbon dioxide and generating electricity by using iron-containing mineral solid waste to transform carbon-containing energy in a stepwise manner. The method proposed in the present invention realizes efficient hierarchical transformation of carbon-containing energy and energy cascade utilization, separation of effective products with low energy consumption, and separation and preparation of pure carbon dioxide and pure hydrogen with low energy consumption, establishes an efficient quality and energy conversion pathway, and improves the economy 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: the method uses 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, obtains hydrogen production precursors and produces pure carbon dioxide as a by-product through graded and step-by-step utilization of different reactive substances in the carbon-containing energy, and finally produces pure hydrogen through a hydrolysis reaction of the hydrogen production precursor; and completely oxidizes the hydrogen production product produced by the previous hydrolysis reaction with air and obtains energy for power generation, thereby realizing the recycling and resource utilization of 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 graded conversion of carbon-containing energy and energy cascade utilization, 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 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 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);

[0010] (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);

[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 fully 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 of the pyrolysis reaction in step (1) can be the flue gas or ash discharged from any reaction process of steps (1) to (3). The pyrolysis products are low-activity solid coke (pyrolysis solid phase product) and high-activity gas (pyrolysis gas), the former is solid coke mainly composed of carbon elements, and the latter is combustible gases such as carbon monoxide, hydrogen and methane. The temperature of the pyrolysis reaction is 450°C-950°C.

[0013] In step (1), a strategy of hierarchical utilization of carbon-containing energy and efficient coupling of its reaction activity with mineral solid waste is adopted. In the initial reduction reactor, the low-activity solid coke produced by the carbon-containing energy reacts with the 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 the 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 the present invention avoids the complicated steps of hydrogen production, purification, conversion and separation reaction; moderate temperature and enhanced reaction kinetics, reasonable temperature coordination operation avoids the process requirements of special equipment and materials; carbon dioxide at the product end is easy to purify, and pollutant concentration is easy to control economically; water-hydrogen is very easy to separate, and pure carbon dioxide and high-grade thermal energy can be obtained in the process. The whole process realizes efficient hierarchical conversion and energy cascade utilization of carbon-containing energy, separation of effective products with low energy consumption, and low-energy separation and preparation of pure carbon dioxide and pure hydrogen, establishes an efficient quality and energy conversion pathway, and improves the economy and cost performance of the overall process.

[0015] The process route of the present invention is: in the preliminary reduction reactor, the low-activity solid coke produced by the carbon-containing energy reacts with the high-activity mineral solid waste to form sub-oxidized mineral solid waste and pure carbon dioxide; the low-activity sub-oxidized mineral solid waste produced further reacts with the high-activity gas produced by the carbon-containing energy in the 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 circulation reaction. No air is introduced during the reduction process, so that the mixing of carbon dioxide and nitrogen is avoided, and the gas phase product after condensation is pure carbon dioxide. At the same time, 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. 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 products. The sub-oxidized hydrogen production product produced by the hydrolysis hydrogen production reactor is completely oxidized in the air regeneration reactor, releasing high-grade thermal energy and coordinating the thermal balance of the entire system.

[0016] Preferably, the iron-containing mineral solid waste described 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.

[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 foregoing 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 4-30min, 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 4-30min.

[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 the prior art, the beneficial effects of the present invention are as follows: the method proposed in the present invention avoids the complicated steps of hydrogen production, purification, conversion and separation reaction; the process requirements of special equipment materials are avoided by using moderate temperature and enhanced reaction kinetics, and reasonable temperature coordination operation; carbon dioxide at the product end is convenient to purify, and pollutant concentration is easy to control economically; water-hydrogen is very easy to separate, and pure carbon dioxide and high-grade thermal energy can also be obtained in the process. The whole process realizes efficient hierarchical conversion and energy cascade utilization of carbon-containing energy, separation of effective products with low energy consumption, and separation and preparation of pure carbon dioxide and pure hydrogen with low energy consumption, establishes an efficient quality and energy conversion pathway, and improves the economy and cost performance of the overall process. DETAILED DESCRIPTION

[0024] The present invention is further described in detail below with reference to the examples. These examples are only used to illustrate the present invention and are not intended to limit the scope of the present invention. The experimental methods in the following examples where specific conditions are not specified are generally based on conventional conditions in the art or conditions recommended by the manufacturer; the raw materials, reagents, etc. used, unless otherwise specified, are considered to be raw materials and reagents that can be obtained through commercial channels such as conventional markets.

[0025] Example 1

[0026] A method for utilizing iron-containing mineral solid waste to convert carbon-containing energy in a stepwise manner to produce 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 the carbon-containing fuel, and pyrolysis reaction is carried out at 600°C to obtain low-activity coal char and high-activity coal pyrolysis gas. In the initial reduction reactor, the first water vapor and carbon dioxide are used as the reaction atmosphere, the temperature is 1000°C, and the molar ratio of carbon dioxide to 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. After condensation treatment, the gas phase products are purified 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°C and a residence time of 10 minutes to obtain a hydrogen production medium (hydrogen production precursor).

[0028] (2) Hydrogen production by hydrolysis of solid waste-based hydrogen production medium: 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, and then a pure hydrogen product is obtained after condensation.

[0029] (3) Air oxidation regeneration of hydrogen production products: The reduced hydrogen production products obtained in step (2) enter an 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, 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] The temperature of the initial reduction reactor in step (1) is 950°C, the molar ratio of carbon dioxide to water vapor is 1:1.5, and the residence time is 30 minutes. The temperature of the deep reduction reactor is 900°C, and the residence time is 20 minutes. The temperature of the hydrolysis hydrogen production reactor in step (2) 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 to water vapor is 1:1, the residence time is 8 minutes, the temperature of the deep reduction reactor is 900°C, the residence time is 4 minutes, and the temperature of the hydrolysis hydrogen production reactor in step (2) is 900°C, and the molar ratio of 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, the biomass is sawdust, the temperature of the initial reduction reactor in step (1) is 900°C, the molar ratio of carbon dioxide to water vapor is 1:0.25, the residence time is 25 minutes, the temperature of the deep reduction reactor is 900°C, the residence time is 15 minutes. The temperature of the hydrolysis hydrogen production reactor in step (2) is 1000°C, and the molar ratio of 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. The temperature of the initial reduction reactor in step (1) 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. The temperature of the hydrolysis hydrogen production reactor in step (2) is 1000°C, and the molar ratio of hydrogen production precursor to water vapor is 1:2.5.

[0047] In this embodiment, it is measured that the carbon capture rate is 95%, the carbon dioxide purity is 95%, and the hydrogen purity is 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 technicians in this technical field, 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 utilizing iron-containing mineral solid waste to convert carbon-containing energy into high-purity hydrogen and by-product carbon dioxide and generate electricity, characterized in that: The method comprises the following steps: the method uses 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, obtains hydrogen production precursors 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; the hydrogen production product produced by the previous hydrolysis reaction is completely oxidized by air and energy is obtained for power generation, thereby realizing the recycling and resource utilization of iron-containing mineral solid waste.

2. The method according to claim 1, characterized in that The specific steps include: (1) hierarchical 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 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); (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 fully 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).

3. The method according to claim 2, characterized in that The iron-containing mineral solid waste described 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.

4. The method according to claim 2, 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.

5. The method according to claim 2, 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 600°C-1300°C, the reaction time is 4-30min, 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 4-30min.

6. The method according to claim 5, 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 8-10min, 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 4-20min.

7. The method according to claim 2, characterized in that: The temperature of the hydrolysis hydrogen production reactor described 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.

8. The method according to claim 7, 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.

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