A steel plant waste heat utilization system for solid hydrogen storage and transportation

Abstract

The present invention discloses a steel mill waste heat utilization system for solid hydrogen storage and transportation. The system includes a first thermoelectric material heat exchanger, located above the chute, which absorbs radiation from blast furnace red slag, heats cold air, and outputs primary heated air. A first thermoelectric converter, located above the chute, absorbs radiation from the blast furnace red slag, converts it into high-temperature heat energy from a radiation plate, exchanges heat with the primary heated air, and outputs secondary heated air. A second thermoelectric material heat exchanger, located at the bottom of the chute, heats the secondary heated air after being heated by a heat panel, and outputs tertiary heated air. A second thermoelectric converter, located at the bottom of the chute, heats the tertiary heated air. The first thermoelectric material heat exchanger is connected to a hydrogen storage module to provide heat energy for solid hydrogen storage. The second thermoelectric converter is connected to a hydrogen release module to provide heat energy for solid hydrogen release. Through multi-stage waste heat recovery, the different preheating temperature requirements for hydrogen storage and release are determined, achieving low-cost operation of solid hydrogen storage and transportation.

Description

Technical Field

[0001] The present invention belongs to the technical field of waste heat utilization, and in particular relates to a steel plant waste heat utilization system for solid hydrogen storage and transportation. Background Art

[0002] While using metal materials to store hydrogen is a safe approach, solid hydrogen storage technology is not yet mature and faces many challenges. Conventional solid hydrogen storage systems rely on constant temperature conditions for hydrogen absorption and desorption. This makes it difficult to adjust the temperature in real time when the absorption and desorption rate requirements change, making it difficult to control the absorption and desorption rate of the hydrogen storage material and ensure that the temperature inside the hydrogen storage tank reaches the optimal absorption and desorption temperature to improve efficiency. A key issue is reducing the cost of hydrogen storage and desorption.

[0003] There are limited means of low-cost hydrogen storage and transportation. Since the process of solid hydrogen storage and transportation requires a temperature of 200-300°C, previous solid hydrogen storage and transportation systems all adopted self-configured heating systems, mostly using electricity as energy, and the energy consumed was equivalent to 30%-40% of the energy of hydrogen storage and transportation, resulting in high costs for solid hydrogen storage and transportation. Summary of the Invention

[0004] The purpose of the present invention is to provide a steel plant waste heat utilization system for solid hydrogen storage and transportation, which can convert steel plant waste heat into the heat required for solid hydrogen storage and transportation, greatly reducing the cost of solid hydrogen storage and transportation.

[0005] In order to solve the above problems, the technical solution of the present invention is:

[0006] A steel mill waste heat utilization system for solid hydrogen storage and transportation, comprising:

[0007] Chutes, which serve as channels for the red slag from blast furnaces;

[0008] A first thermoelectric material heat exchanger is arranged above the chute; the hot end of the first thermoelectric material heat exchanger is a heating panel that absorbs radiation from the blast furnace red slag, and the heating panel is provided with multiple flow channels, which are used to sequentially heat the cold air flowing through it and output primary heated air;

[0009] A first thermoelectric converter is arranged above the chute; the cold end of the first thermoelectric converter is the primary heated air, and the hot end absorbs the radiation energy of the blast furnace red slag and converts it into high-temperature heat energy of the radiation plate, exchanges heat with the primary heated air, and outputs secondary heated air;

[0010] A second thermoelectric material heat exchanger is installed at the bottom of the chute. The hot end of the second thermoelectric material heat exchanger is a heating panel of blast furnace red slag. After the secondary heated air is heated by the heating panel, the tertiary heated air is output;

[0011] A second thermoelectric converter is laid at the bottom of the chute, wherein the cold end of the second thermoelectric converter is the three-stage heated air and the hot end is the blast furnace red slag;

[0012] The first thermoelectric material heat exchanger is connected to the hydrogen storage module to provide thermal energy for solid hydrogen storage; the second thermoelectric converter is connected to the hydrogen release module to provide thermal energy for solid hydrogen release.

[0013] According to one embodiment of the present invention, a water-cooled wall heat exchanger is provided above the chute to absorb the radiation energy of the blast furnace red slag, and air enters the pipe of the water-cooled wall heat exchanger to absorb the radiation energy of the blast furnace red slag.

[0014] According to one embodiment of the present invention, a water-cooled wall heat exchanger is provided in the chute, immersed in the blast furnace red slag, absorbing the thermal energy of the blast furnace red slag, and air enters the pipe of the water-cooled wall heat exchanger to absorb the thermal energy, further increasing the air temperature.

[0015] According to an embodiment of the present invention, the second thermoelectric material heat exchanger uses Half-Heusler base as the thermoelectric conversion material.

[0016] According to an embodiment of the present invention, the first thermoelectric converter uses PbTe as the thermoelectric conversion material.

[0017] Due to the adoption of the above technical solution, the present invention has the following advantages and positive effects compared with the prior art:

[0018] 1) In one embodiment of the present invention, a steel mill waste heat utilization system for solid hydrogen storage and transportation comprises a first thermoelectric heat exchanger, located above the chute, which absorbs radiation from the blast furnace red slag, heats cold air, and outputs primary heated air. A first thermoelectric converter, located above the chute, absorbs the radiation energy from the blast furnace red slag, converts it into high-temperature heat energy from a radiation panel, exchanges heat with the primary heated air, and outputs secondary heated air. A second thermoelectric heat exchanger, located at the bottom of the chute, heats the secondary heated air after being heated by a heat panel, and outputs tertiary heated air. A second thermoelectric converter, located at the bottom of the chute, heats the tertiary heated air. The first thermoelectric heat exchanger is connected to the hydrogen storage module to provide heat energy for solid hydrogen storage, and the second thermoelectric converter is connected to the hydrogen release module to provide heat energy for solid hydrogen release. Through multi-stage waste heat recovery, the different preheating temperature requirements for hydrogen storage and release are determined, achieving low-cost operation of solid hydrogen storage and transportation.

[0019] 2) In an embodiment of the present invention, a steel plant waste heat utilization system for solid hydrogen storage and transportation is provided with multiple flow channels on the heating panel of the thermoelectric material heat exchanger. After the cold air enters the first flow channel of the heat exchanger, it is continuously heated along the heating surface, and then enters the second flow channel, and so on. On the one hand, the flow rate is increased to promote the heat exchange effect, and on the other hand, the heat exchange area is increased, thereby efficiently raising the air temperature.

[0020] 3) In one embodiment of the present invention, a steel mill waste heat utilization system for solid hydrogen storage and transportation employs water-cooled walls within the system space. This fully absorbs the radiant energy from the blast furnace slag, allowing air entering the pipes to absorb the radiant energy. Furthermore, to further increase air temperature, the water-cooled walls are placed within the chute, ensuring that the slag level is higher than the pipes, completely immersing the pipes in the slag, further rapidly raising the air temperature. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 This is a block diagram of a steel plant waste heat utilization system for solid hydrogen storage and transportation in one embodiment of the present invention.

[0022] Description of reference numerals:

[0023] 1: First thermoelectric material heat exchanger; 2: First thermoelectric converter; 3: Second thermoelectric material heat exchanger; 4: Second thermoelectric converter; 5: Hydrogen storage module; 6: Hydrogen release module. DETAILED DESCRIPTION

[0024] The advantages and features of the present invention will become more apparent from the following description and claims.

[0025] Currently, the vast amount of waste heat within steel mills is difficult to utilize. The significant sensible heat of blast furnace slag is wasted, causing significant environmental pollution and consuming significant amounts of water resources. To address this difficulty, this embodiment proposes a method for recovering waste heat from blast furnace slag by coupling thermoelectricity, radiation, and thermal conductivity. This waste heat recovery system, used for solid hydrogen storage and transportation, offers significant advantages such as zero pollution and high efficiency. It converts low-grade thermal energy into high-grade thermal energy and electricity, and has promising prospects for industrial application.

[0026] Please see Figure 1 The steel mill waste heat utilization system for solid hydrogen storage and transportation provided in this embodiment includes:

[0027] Chutes, which serve as channels for the red slag from blast furnaces;

[0028] A first thermoelectric material heat exchanger 1 is arranged above the chute; the hot end of the first thermoelectric material heat exchanger is a heating panel that absorbs radiation from the blast furnace red slag, and a plurality of flow channels are provided on the heating panel, which are used to sequentially heat the cold air flowing through and output primary heated air;

[0029] The first thermoelectric converter 2 is arranged above the chute; the cold end of the first thermoelectric converter is the first-stage heated air, and the hot end absorbs the radiation energy of the blast furnace red slag and converts it into high-temperature heat energy of the radiation plate, exchanges heat with the first-stage heated air, and outputs the second-stage heated air;

[0030] The second thermoelectric material heat exchanger 3 is laid at the bottom of the chute. The hot end of the second thermoelectric material heat exchanger is a heating panel of blast furnace red slag. After the secondary heated air is heated by the heating panel, the tertiary heated air is output;

[0031] The second thermoelectric converter 4 is laid at the bottom of the chute, the cold end of the second thermoelectric converter is the three-stage heated air, and the hot end is the blast furnace red slag;

[0032] Among them, the first thermoelectric material heat exchanger is connected to the hydrogen storage module 5 to provide thermal energy for solid hydrogen storage; the second thermoelectric converter is connected to the hydrogen release module 6 to provide thermal energy for solid hydrogen release.

[0033] Specifically, to ensure that the blast furnace slag provided by the steel plant is fully compatible with the designed preheating and utilization device, it is necessary to calculate whether the entire system can achieve a closed energy system. Determining the appropriate blast furnace slag supply is crucial to the entire industrial process. It is important to understand that within the entire process, the chute size affects both the thermoelectric conversion area and the air-to-slag heat exchange area. Therefore, the chute dimensions are defined as L, D, and H, respectively. A thermal utilization efficiency η of 70% is assumed for all heat exchange processes.

[0034] The main waste heat utilization in the system can be divided into two parts, namely electrical energy and thermal energy:

[0035] First electric energy: The thermoelectric converter laid at the bottom of the chute is determined by the bottom area of the chute and the thermoelectric conversion efficiency. The bottom area of the chute is S1=L×D. The hot end is slag with an average temperature of 1200℃, and the cold end is three-stage heated air.

[0036] Secondary Electric Energy: The thermoelectric converter located above the chute absorbs the radiation energy from the red slag to generate a hot end of approximately 360°C. The cold end is the first-stage heated air. This is a medium-temperature range thermoelectric conversion.

[0037] First heat energy: The thermoelectric material heat exchanger is arranged on the top of the chute. The hot end is the heating surface that absorbs infrared radiation. The total heat transfer coefficient K1 between the hot end and the first-stage heated air is 60W / (m2·K), the heat exchange temperature difference is ΔT1, and the heat exchange area is S1.

[0038] Secondary heat energy: The water-cooled wall above the chute absorbs radiation energy and further transfers it to the air in the tube. The total heat transfer coefficient K1 between the heated surface and the secondary heated air is 60W / (m2·K), the heat exchange temperature difference is ΔT2, and the heat exchange area is S2.

[0039] The third heat energy: The thermoelectric material heat exchanger is arranged at the bottom of the chute. The hot end is high-temperature red slag. The total heat transfer coefficient K1 between the heated surface and the three-stage heating air is 60W / (m2·K), the heat exchange temperature difference is ΔT3, and the heat exchange area is S3.

[0040] Fourth, heat energy: The water-cooled walls inside the chute absorb heat conduction energy, which is determined by the convection heat transfer area and the total heat transfer coefficient. Assuming the coil diameter is 2.36 cm and the spacing is 1 cm, the total convection heat transfer area is S4 = 0.0079 × (D / (0.0336) × L + D). The total heat transfer coefficient K2 between the blast furnace red slag and the fourth-stage heating air is 100 W / (m2·K), and the heat exchange temperature difference is ΔT4.

[0041] The thermoelectric converter located above the chute converts the radiation energy of the red slag into high-temperature heat energy from the radiation plate. The heat is then converted to electricity using the radiation plate as the hot end and cold air as the cold end. The thermoelectric conversion area is assumed to be three times the chute area, or 3S1. Based on blackbody radiation and Kirchhoff's law, the heated surface temperature is calculated to be 270°C, while the cold end is room-temperature air at 25°C. The properties of the thermoelectric materials are selected as follows: Half-Heusler (HH) was chosen as the thermoelectric conversion material for the high-temperature section (the bottom of the chute), with a comprehensive large-scale conversion efficiency of 0.7W / cm⁻². PbTe was chosen as the thermoelectric conversion material for the medium-temperature section (the thermoelectric converter), with a conversion efficiency of 0.35W / cm⁻². The total electrical energy provided by the system is Epro = 0.7×S1 + 1.05×S1 = 1.75S1; and the total thermal energy provided is Qpro = ΔT1×S1×K1 + ΔT2×S2×K1 + ΔT3×S3×K1 + ΔT4×S4×K2.

[0042] Application examples:

[0043] The waste heat utilization system needs to provide 40KW of heat, that is, 144,000,000J of thermal energy. According to the requirements, this part of the heat will be provided in the form of 800℃ hot air. It is calculated by Qdem=C×M×ΔT, and the hot air volume required by the system is 206kg / h. The 800℃ hot air is mainly 25℃ room temperature air. First, the first stage preheating is carried out. The 25℃ air exchanges heat with the heating surface of the thermoelectric material and is initially heated to 100℃ (a heat exchange area of 0.97m2 is required, that is, the design area of S1 should be 0.97m2); the second stage heating is carried out. The 100℃ air exchanges heat with the water-cooled wall heat exchanger 1, absorbs the radiation energy of the red slag, and is heated to 250℃. According to the investigation, it is assumed that the wall temperature of the water-cooled wall is 400℃, that is, S2 = 1.81m2; the third stage heating is carried out. The 250℃ air exchanges heat with the heating surface at the bottom of the chute and is heated to 350℃ (a heat exchange area of S3 = 0.64m2 is required); the fourth stage heating is carried out. The 350℃ hot air exchanges heat with the high-temperature slag through the spiral folded tube and is heated to T4℃; the fifth stage heating is carried out. The air is electrically heated by the converted electrical energy, and finally 206kg / h of 800℃ hot air is obtained. To determine the appropriate amount of red slag required for the system, we assumed a 5m chute length, a 5cm red slag level, and a flow rate of 2m / min. Calculations show that a red slag supply of at least 3100kg / h would meet the 40kW heat requirement. The project owner can provide a maximum red slag capacity of 5t / h, so while meeting the current heat requirement, it can still supply approximately 23kW of electricity.

[0044] Both solid hydrogen storage and discharge require a heat source. Storage requires a heat source of 200-250°C (200°C is common), a heat requirement of 400kcal / kgH2, and a charging time of 8-14 hours. Desorption requires a temperature of 350°C (350°C is common), a heat requirement of 11,800kcal / kgH2 (equivalent to 1.69kgce / kg H2, or 1.69tce per ton of H2), and a desorption time of 10-15 hours.

[0045] The SOEC hydrogen production technology also requires a heat source. A 200kW SOEC requires approximately 50kW of heat, or 44,084kcal / h (6.29kgce / h), which translates to 80kg / h of steam at 210°C. For details, see the heat source requirements for hydrogen storage and SOEC:

[0046]

[0047] The embodiments of the present invention have been described in detail above with reference to the accompanying drawings, but the present invention is not limited to the above embodiments. Even if various changes are made to the present invention, if these changes fall within the scope of the claims of the present invention and their equivalents, they still fall within the scope of protection of the present invention.

Claims

1. A steel plant waste heat utilization system for solid hydrogen storage and transportation, characterized in that: include: Chutes, which serve as channels for the red slag from blast furnaces; a first thermoelectric material heat exchanger, arranged above the chute; The hot end of the first thermoelectric material heat exchanger is a heating panel that absorbs radiation from blast furnace red slag. The heating panel is provided with multiple flow channels, which are used to sequentially heat the cold air flowing through it and output primary heated air. A first thermoelectric converter is arranged above the chute; the cold end of the first thermoelectric converter is the primary heated air, and the hot end absorbs the radiation energy of the blast furnace red slag and converts it into high-temperature heat energy of the radiation plate, exchanges heat with the primary heated air, and outputs secondary heated air; A second thermoelectric material heat exchanger is installed at the bottom of the chute. The hot end of the second thermoelectric material heat exchanger is a heating panel of blast furnace red slag. After the secondary heated air is heated by the heating panel, the tertiary heated air is output; A second thermoelectric converter is laid at the bottom of the chute, wherein the cold end of the second thermoelectric converter is the three-stage heated air and the hot end is the blast furnace red slag; The first thermoelectric material heat exchanger is connected to the hydrogen storage module to provide thermal energy for solid hydrogen storage; the second thermoelectric converter is connected to the hydrogen release module to provide thermal energy for solid hydrogen release.

2. The steel plant waste heat utilization system for solid hydrogen storage and transportation according to claim 1, characterized in that: A water-cooled wall heat exchanger is arranged above the chute to absorb the radiation energy of the blast furnace red slag. Air enters the pipe of the water-cooled wall heat exchanger to absorb the radiation energy of the blast furnace red slag.

3. The steel mill waste heat utilization system for solid hydrogen storage and transportation according to claim 1 or 2, characterized in that: A water-cooled wall heat exchanger is arranged in the chute and immersed in the blast furnace red slag to absorb the heat conduction energy of the blast furnace red slag. The air enters the pipe of the water-cooled wall heat exchanger to absorb the heat conduction energy, thereby further increasing the air temperature.

4. The steel plant waste heat utilization system for solid hydrogen storage and transportation according to claim 1, characterized in that: The second thermoelectric material heat exchanger uses Half-Heusler base as the thermoelectric conversion material.

5. The steel mill waste heat utilization system for solid hydrogen storage and transportation according to claim 1, characterized in that: The first thermoelectric converter uses PbTe as the thermoelectric conversion material.

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