A ferro-oxygen cycle system and a self-heating coupled iron-based metal fuel energy storage device

Abstract

This invention provides a ferro-oxygen cycle system and a self-heating coupled iron-based metal fuel energy storage device, relating to the field of energy storage. The system includes an iron production stage, an iron diversion stage, and an iron oxide stage. In the iron production stage, hydrogen gas input into the system reduces iron oxide to iron through a reduction reaction. In the iron diversion stage, the reduced iron is divided into multiple branches. In the iron oxide stage, the iron from the multiple branches undergoes an oxidation reaction to produce iron oxide, which is then collected and reintroduced into the iron production stage for the next cycle. This invention employs the aforementioned ferro-oxygen cycle system and self-heating coupled iron-based metal fuel energy storage device. By introducing a microreactor, it improves the energy storage and transportation efficiency of the ferro-oxygen cycle, contributing to energy decarbonization.

Description

Technical Field

[0001] This invention relates to the field of energy storage, and in particular to a ferro-oxygen cycle system and a self-heating coupled iron-based metal fuel energy storage device. Background Technology

[0002] With the development of renewable energy technologies, the technologies for their consumption and application urgently need to be developed. To achieve long-distance transportation of renewable energy, some scholars have attempted to store renewable energy using batteries or chemical media such as hydrogen and ammonia, and to achieve long-distance transportation through solutions such as methanol-loaded hydrogen and magnesium-based solid-state hydrogen storage. However, the volumetric energy density of these media is limited, and bottlenecks still exist in high-density, high-security storage and transportation, restricting the large-scale utilization of renewable electricity.

[0003] Faced with the mismatch between renewable energy sources and end-user loads in both time and space, researchers have turned their attention to metallic fuels, which have high energy density and are easy to store and transport. Since the 1970s, metals have been used in the military industry; in 2018, some scholars repositioned them as chemical carriers of renewable electricity to achieve cross-regional energy storage and transportation integration.

[0004] In recent years, some scholars have proposed using the iron-oxygen cycle as a long-distance storage and transportation technology for renewable energy, and have put forward a transformation scheme for traditional coal-fired power plants based on this method. However, current research has not optimized the thermal management of this technology path. It basically adopts a one-way open-loop mode in which all iron is sent out for combustion into steam Rankine. The system is highly dependent on external heat sources or high-grade hydrogen, and the waste heat of high-temperature flue gas on the combustion side cannot be fed back to the reduction side, resulting in a 15-25% loss of usable energy. Summary of the Invention

[0005] The purpose of this invention is to provide a ferro-oxygen cycle system and a self-heating coupled iron-based metal fuel energy storage device. The ferro-oxygen cycle process is the core, and renewable energy is absorbed through alkaline water electrolysis hydrogen production technology. Self-heating is achieved through micro-burners, improving the overall performance of the system. The ferro-oxygen cycle products are transported by rail and green electricity is produced by the end-steam Rankine cycle.

[0006] To achieve the above objectives, the present invention provides an iron-oxygen cycle system, comprising an iron production stage, an iron diversion stage, and an iron oxide stage; During the iron production stage, hydrogen gas introduced into the system reduces iron oxide to iron through a reduction reaction. During the iron diversion stage, the reduced iron is divided into multiple branches. In the iron oxide stage, iron from multiple branches undergoes an oxidation reaction to produce iron oxide, which is then collected and fed back into the iron production stage to enter the next cycle.

[0007] Preferably, the iron production stage includes a high-temperature heat exchanger, a reduction reactor, and a micro burner; the high-temperature heat exchanger preheats the input hydrogen gas, which then flows into the reduction reactor to undergo a reduction reaction and produce iron; wherein, during the reduction reaction, the micro burner heats the reduction reactor.

[0008] Preferably, the iron diversion stage includes a first medium-temperature heat exchanger, a diverter, and a storage tank. After the iron is preheated with hydrogen by the high-temperature heat exchanger, it is cooled by the first medium-temperature heat exchanger and then divided into two branches by the diverter. One branch flows to the storage tank to drive power generation as fuel, and the other branch flows to the micro burner.

[0009] Preferably, the iron oxide stage includes a first circulating water mixer, where iron flowing to the micro burner reacts with oxygen to release heat and produce iron oxide; when used as fuel to drive power generation, it is oxidized to iron oxide; the iron oxide produced by the two branches is mixed through the first circulating water mixer and flows to the reduction reactor to enter the next cycle.

[0010] Preferably, the reduction reactor is also connected to an external electrical source as supplementary energy to provide energy for the reduction reaction in the reduction reactor; The miniature burner is also connected to an external oxygen source for the iron oxidation reaction, which releases heat.

[0011] A self-heating coupled iron-based metal fuel energy storage device includes an iron-oxygen cycle system, an alkaline water electrolysis hydrogen production system, and a Rankine cycle system. The alkaline water electrolysis hydrogen production system produces hydrogen and oxygen by electrolyzing water. The hydrogen is fed into the high-temperature heat exchanger in the iron-oxygen cycle system to reduce iron oxide; the oxygen is fed into the micro burner in the iron-oxygen cycle system for oxidation reaction. The Rankine cycle system uses iron from the storage tank in the ferrite cycle system to generate heat in the burner, which powers the steam Rankine cycle and generates electricity to supply power to the city.

[0012] Preferably, the alkaline water electrolysis hydrogen production system includes a second circulating water mixer, a circulating pump, a second medium-temperature heat exchanger, an electrolytic cell, a product separator, a first gas-liquid separator, and a second gas-liquid separator. The electrolyte is mixed in the second circulating water mixer, pressurized by the circulating pump, and preheated by the second medium-temperature heat exchanger. Then, driven by green electricity, the electrolysis reaction is completed in the electrolytic cell to generate hydrogen and oxygen. The hydrogen, oxygen and electrolyte flow out of the electrolytic cell and pass through the product separator to separate the electrolyte carrying oxygen and the electrolyte carrying hydrogen. The electrolyte carrying oxygen passes through the first gas-liquid separator to separate the oxygen and the electrolyte, and the electrolyte carrying hydrogen passes through the second gas-liquid separator to separate the hydrogen and the electrolyte. The electrolyte separated by the first and second gas-liquid separators is used as supplementary electrolyte and flows into the circulating water mixer for mixing, thus starting the next cycle.

[0013] Preferably, when the first medium-temperature section heat exchanger and the second medium-temperature section heat exchanger are the same heat exchanger, the first medium-temperature section heat exchanger uses the heat released by the iron to heat the electrolyte flowing through the second medium-temperature section heat exchanger.

[0014] Preferably, when the first intermediate temperature section heat exchanger and the second intermediate temperature section heat exchanger are not the same heat exchanger, the first intermediate temperature section heat exchanger cools the iron naturally, and the second intermediate temperature section heat exchanger uses electrical energy to heat the electrolyte.

[0015] Preferably, the Rankine cycle system can also be replaced by the Breton cycle system or the Karina cycle system.

[0016] Therefore, the present invention employs the aforementioned iron-oxygen cycle system and a self-heating coupled iron-based metal fuel energy storage device, and the technical effects are as follows: This paper proposes for the first time an iron-based metal fuel energy storage method based on chemical loop self-heating coupling. The lattice oxygen and heat released by the micro-combustion zone are supplied in situ to the reduction zone within the same reactor, achieving zero external hydrogen supply for the reduction reaction. By making economical system process modifications, we can achieve efficient storage, transportation and consumption of renewable energy, and effectively improve energy storage and transportation efficiency.

[0017] Using the oxygen generated during water electrolysis for combustion in a microreactor improves the utilization rate of the system's products. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of a ferro-oxygen cycle system and a self-heating coupled iron-based metal fuel energy storage device according to the present invention. Figure 2 This is a schematic diagram of a reference system for a ferro-oxygen cycle system and a self-heating coupled iron-based metal fuel energy storage device according to the present invention.

[0019] Figure Labels Mixer-01, Second circulating water mixer; Pump-01, Circulating pump; HX-02, Second medium-temperature heat exchanger; Alkaline electrolyzer, Electrolytic cell; Sep-01, Product separator; Sep-02, First gas-liquid separator; Sep-03, Second gas-liquid separator; HX-02, High-temperature section heat exchanger; HX-01, First medium-temperature section heat exchanger; Sep-04, Diverter; Storage tank; Reduction reactor; Micro burner; Mix-02, First circulating water mixer; Combustion chamber. Detailed Implementation

[0020] The technical solution of the present invention will be further described below with reference to the accompanying drawings and embodiments.

[0021] Unless otherwise defined, the technical or scientific terms used in this invention shall have the ordinary meaning as understood by one of ordinary skill in the art to which this invention pertains.

[0022] Example 1 like Figure 1 As shown, a ferro-oxygen cycle system and a self-heating coupled iron-based metal fuel energy storage device are presented for the first time. A combustion-reduction self-heating coupling based on the ferro-oxygen cycle is proposed, introducing 10–30% highly reactive iron into a micro fluidized bed to undergo a partial oxidation-reduction coupled reaction. A high-efficiency ferro-oxygen cycle energy storage device based on a micro burner is designed. With the aid of oxygen produced by water electrolysis, a portion of the reduction product iron is burned to power the reduction reactor, while the remaining portion powers the Rankine cycle to generate electricity through the combustion chamber of the burner. This achieves self-heating operation of the reduction reaction with zero external hydrogen supply and zero electric heating. The self-heating process based on the micro burner reduces the overall energy consumption required for the reduction reaction and improves the overall efficiency of the system.

[0023] An iron-oxygen cycle system includes an iron production stage, an iron diversion stage, and an iron oxide stage; In the iron production stage, hydrogen gas introduced into the system reduces iron oxide to iron through a reduction reaction. This stage includes a high-temperature heat exchanger (HX-02), a reduction reactor, and a micro burner. The HX-02 preheats the introduced hydrogen gas before it flows into the reduction reactor, where a reduction reaction occurs, producing iron. During the reduction reaction, the micro burner heats the reduction reactor. The reduction reactor is also externally connected to electricity as supplementary energy to power the reduction reaction. The micro burner is also externally connected to oxygen for the iron oxidation reaction, releasing heat.

[0024] In the iron diversion stage, the reduced iron is divided into multiple branches. The iron diversion stage includes the first medium-temperature heat exchanger HX-01, the diverter Sep-04, and the storage tank. After the iron is preheated with hydrogen by the high-temperature heat exchanger HX-02, it is preheated with electrolyte by the first medium-temperature heat exchanger HX-01 while its temperature is reduced. Then, it is divided into two branches by the diverter Sep-04. One branch flows to the storage tank to drive power generation as fuel, and the other branch flows to the micro burner.

[0025] In the iron oxide stage, iron from multiple branches undergoes an oxidation reaction to produce iron oxide, which is then collected and fed back into the iron production stage to enter the next cycle. The iron oxide stage includes the first circulating water mixer Mix-02, where iron flowing to the micro burner undergoes an oxidation reaction with oxygen, releasing heat and producing iron oxide. When used as fuel to drive power generation, it is oxidized into iron oxide. The iron oxide produced by the two branches is mixed in the first circulating water mixer Mix-02 and flows to the reduction reactor to enter the next cycle.

[0026] A self-heating coupled iron-based metal fuel energy storage device includes an iron-oxygen cycle system, an alkaline water electrolysis hydrogen production system, and a Rankine cycle system. The alkaline water electrolysis hydrogen production system produces hydrogen and oxygen by electrolyzing water. The hydrogen is fed into the high-temperature heat exchanger HX-02 in the iron-oxygen cycle system to reduce iron oxide; the oxygen is fed into the micro burner in the iron-oxygen cycle system for oxidation.

[0027] The alkaline water electrolysis hydrogen production system includes a second circulating water mixer Mixer-01, a circulating pump Pump-01, a second medium-temperature heat exchanger HX-02, an electrolysis cell Alkaline electrolyzer, a product separator Sep-01, a first gas-liquid separator Sep-02, and a second gas-liquid separator Sep-03. The electrolyte is mixed in the second circulating water mixer Mixer-01, pressurized by the circulating pump Pump-01, and preheated by the second medium-temperature heat exchanger HX-02. Then, driven by green electricity, the electrolysis reaction is completed in the Alkaline electrolyzer to generate hydrogen and oxygen. The hydrogen, oxygen and electrolyte flow out of the Alkaline electrolyzer and pass through the product separator Sep-01 to separate the electrolyte carrying oxygen and the electrolyte carrying hydrogen. The electrolyte carrying oxygen passes through the first gas-liquid separator Sep-02 to separate the oxygen and the electrolyte, and the electrolyte carrying hydrogen passes through the second gas-liquid separator Sep-03 to separate the hydrogen and the electrolyte.

[0028] The electrolyte separated by the first gas-liquid separator Sep-02 and the second gas-liquid separator Sep-03 flows into the circulating water mixer as a supplementary electrolyte for mixing and the next cycle.

[0029] When the first medium-temperature heat exchanger HX-01 and the second medium-temperature heat exchanger HX-02 are the same heat exchanger, the first medium-temperature heat exchanger HX-01 uses the heat released by the iron to heat the electrolyte flowing through the second medium-temperature heat exchanger HX-02.

[0030] When the first medium-temperature section heat exchanger HX-01 and the second medium-temperature section heat exchanger HX-02 are not the same heat exchanger, the first medium-temperature section heat exchanger HX-01 cools the iron naturally, while the second medium-temperature section heat exchanger HX-02 uses electrical energy to heat the electrolyte.

[0031] The Rankine cycle system uses iron from the storage tank in the ferrite cycle to generate heat in the combustion chamber, powering the steam Rankine cycle and producing green electricity to power the alkaline water electrolysis hydrogen production system. The Rankine cycle system can also be replaced by the Brayton cycle or the Karina cycle system.

[0032] This embodiment sets up a 300 MW zero-carbon emission power generation system that uses iron as a renewable energy carrier. The system uses PLPK series turbines and INGERSOLL-RAND series compressors, and all heat exchangers are counter-current heat exchangers. A reference system (such as...) Figure 2 As shown, a ferro-oxygen cycle system using hydrogen as fuel for a microreactor was established. The reference system diagram and operating parameters are compared below: Table 1 Comparison of System Performance and Functions

[0033] Therefore, this invention employs the aforementioned iron-oxygen cycle system and a self-heating coupled iron-based metal fuel energy storage device, introducing a micro-burner into the iron-oxygen cycle. By burning part of the product iron, the heat generated in the reduction reactor is replenished. The product iron is then transported to the burner in a Rankine cycle power plant to drive electricity generation. This invention focuses on the renewable energy consumption process, improving the energy storage and transportation efficiency of the iron-oxygen cycle by introducing a micro-reactor, thus contributing to energy decarbonization.

[0034] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the technical solutions of the present invention, and these modifications or equivalent substitutions cannot cause the modified technical solutions to deviate from the spirit and scope of the technical solutions of the present invention.

Claims

1. A ferrite circulation system, characterized in that, This includes the iron production stage, the iron diversion stage, and the iron oxide stage; During the iron production stage, hydrogen gas introduced into the system reduces iron oxide to iron through a reduction reaction. During the iron diversion stage, the reduced iron is divided into multiple branches; The iron diversion stage includes a first medium-temperature heat exchanger, a diverter, and a storage tank. After the iron is preheated with hydrogen by the high-temperature heat exchanger, it is cooled down by the first medium-temperature heat exchanger and then divided into two branches by the diverter. One branch flows to the storage tank to drive power generation as fuel. The iron oxide formed after power generation and the iron oxide formed by oxidation in the other branch are combined in the first circulating water mixer of the iron oxide stage and returned to the reduction reactor to enter the next iron-oxygen cycle. Another branch flows to a micro-burner, which receives oxygen and causes the iron in this branch to oxidize, releasing heat to heat the reduction reactor. In the iron oxide stage, iron from multiple branches undergoes an oxidation reaction to produce iron oxide, which is then collected and fed back into the iron production stage to enter the next cycle.

2. The ferrite circulation system according to claim 1, characterized in that, The iron production stage includes a high-temperature heat exchanger, a reduction reactor, and a micro burner. The high-temperature heat exchanger preheats the input hydrogen gas, which then flows into the reduction reactor to undergo a reduction reaction and produce iron. During the reduction reaction, the micro burner heats the reduction reactor.

3. The ferrite circulation system according to claim 1, characterized in that, The iron oxide stage includes a first circulating water mixer, where iron flowing to the micro-burner reacts with oxygen to release heat and produce iron oxide; when used as fuel to drive power generation, it is oxidized into iron oxide; the iron oxide produced by the two branches is mixed in the first circulating water mixer and flows to the reduction reactor to enter the next cycle.

4. The ferrite circulation system according to claim 1, characterized in that, The reduction reactor is also connected to an external electrical source to provide energy for the reduction reaction in the reactor as a supplementary energy source. The miniature burner is also connected to an external oxygen source for the iron oxidation reaction, which releases heat.

5. A self-heating coupled iron-based metal fuel energy storage device, characterized in that, Includes the iron-oxygen cycle system, the alkaline water electrolysis hydrogen production system, and the Rankine cycle system as described in any one of claims 1-4; The alkaline water electrolysis hydrogen production system produces hydrogen and oxygen by electrolyzing water. The hydrogen is fed into the high-temperature heat exchanger in the iron-oxygen cycle system to reduce iron oxide; the oxygen is fed into the micro burner in the iron-oxygen cycle system for oxidation reaction. The Rankine cycle system uses iron from the storage tank in the ferrite cycle system to generate heat in the burner, which powers the steam Rankine cycle and generates electricity to supply power to the city.

6. A self-heating coupled iron-based metal fuel energy storage device according to claim 5, characterized in that, The alkaline water electrolysis hydrogen production system includes a second circulating water mixer, a circulating pump, a second medium-temperature heat exchanger, an electrolytic cell, a product separator, a first gas-liquid separator, and a second gas-liquid separator. The electrolyte is mixed in the second circulating water mixer, pressurized by the circulating pump, and preheated by the second medium-temperature heat exchanger. Then, driven by green electricity, the electrolysis reaction is completed in the electrolytic cell to generate hydrogen and oxygen. The hydrogen, oxygen and electrolyte flow out of the electrolytic cell and pass through the product separator to separate the electrolyte carrying oxygen and the electrolyte carrying hydrogen. The electrolyte carrying oxygen passes through the first gas-liquid separator to separate the oxygen and the electrolyte, and the electrolyte carrying hydrogen passes through the second gas-liquid separator to separate the hydrogen and the electrolyte. The electrolyte separated by the first and second gas-liquid separators is used as supplementary electrolyte and flows into the second circulating water mixer for mixing, thus starting the next cycle.

7. A self-heating coupled iron-based metal fuel energy storage device according to claim 5, characterized in that, When the first and second intermediate temperature heat exchangers are the same heat exchanger, the first intermediate temperature heat exchanger uses the heat released by the iron to heat the electrolyte flowing through the second intermediate temperature heat exchanger.

8. A self-heating coupled iron-based metal fuel energy storage device according to claim 5, characterized in that, When the first and second intermediate temperature heat exchangers are not the same heat exchanger, the first intermediate temperature heat exchanger cools the iron naturally, while the second intermediate temperature heat exchanger uses electrical energy to heat the electrolyte.

9. A self-heating coupled iron-based metal fuel energy storage device according to claim 5, characterized in that, The Rankine cycle system is replaced with the Breton cycle system or the Karina cycle system.

Images