Self-circulation waste heat recovery method for graphite electrode production

Abstract

The invention discloses a self-circulation waste heat recovery method for graphite electrode production, which comprises the following steps: S1) heat energy absorption: in the cooling stage of a graphitization kiln, collecting high-temperature waste heat by using a closed container, and filling the closed container with a phase change material; s2) heat energy storage: the phase change material absorbs heat at high temperature and converts the heat into a liquid state to store heat energy; s3) releasing heat energy: cooling the closed container by adopting a cooling device, so that the phase-change material is solidified again and the stored heat is released; and S4) heat energy reutilization: the cooling device absorbs heat released by the phase change material, and waste heat utilization is realized through the heat exchange device. According to the self-circulation waste heat recovery method for graphite electrode production, waste heat of the graphitization kiln can be efficiently recovered, energy waste is reduced, the cooling time is shortened, and the production efficiency is improved.

Description

Technical Field

[0001] The present invention relates to a self - circulating waste heat recovery method, and particularly to a self - circulating waste heat recovery method for graphite electrode production. Background Art

[0002] During the production process of a graphitization furnace, electrodes are required to heat the graphitization furnace, and the maximum temperature of the furnace can reach 3000°C. After heating, it enters the cooling process. The current process is natural cooling. While cooling, the material is discharged. After the surface layer is cooled to below 500°C, a suction method is used to discharge the cooled heat - insulating material or product. This process is repeated until the discharging is completed. According to the current process, it takes about 8 hours for the 15 - cm - thick surface layer material to be cooled to below 500°C, and the discharging process for each furnace takes more than 20 days. Natural cooling severely restricts the production rate of products. At the same time, this part of the heat is not effectively recovered and utilized, resulting in waste of resources. Due to the high temperature of the graphite furnace, the maximum working temperature of most materials is 1300°C, which limits the use of many heat - exchange methods. At the same time, in order to ensure that the quality of graphite products is not damaged, the implementation of direct - contact heat - exchange equipment is difficult and has many problems, while non - contact heat - exchange methods have better application prospects. Summary of the Invention

[0003] The technical problem to be solved by the present invention is to provide a self - circulating waste heat recovery method for graphite electrode production, which can efficiently recover the waste heat of the graphitization furnace, reduce energy waste, shorten the cooling time, and improve production efficiency.

[0004] The technical solution adopted by the present invention to solve the above - mentioned technical problem is to provide a self - circulating waste heat recovery method for graphite electrode production, including the following steps: S1) Heat energy absorption: During the cooling stage of the graphitization furnace, a closed container filled with a phase - change material is used to collect high - temperature waste heat; S2) Heat energy storage: The phase - change material absorbs heat at high temperature and transforms into a liquid state to store heat energy; S3) Heat energy release: A cooling device is used to cool the closed container, so that the phase - change material solidifies again and releases the stored heat; S4) Heat energy reuse: The released heat is recycled through a heat - exchange device for waste heat recovery.

[0005] Further, the phase - change material is a high - temperature metal alloy or inorganic salt material with a melting point between 600°C and 1000°C.

[0006] Further, the high - temperature metal alloy is sodium - potassium alloy, magnesium - aluminum alloy or copper - aluminum alloy.

[0007] Further, the inorganic salts are lithium carbonate, calcium chloride or potassium nitrate.

[0008] Further, the material of the closed container is tungsten - based alloy, tantalum - based alloy, rhenium - based alloy or molybdenum - based alloy.

[0009] Furthermore, the outer part of the closed container is coated with a heat-insulating layer.

[0010] Furthermore, the number of the closed containers is multiple, and they are arranged in an equidistant array and are attached to the graphite heat-insulating layer of the graphitization furnace.

[0011] Furthermore, the cooling device adopts an air cooling, liquid cooling or hybrid cooling method, and is provided with an automatic control device for adjusting the cooling rate between 30-60 °C / h.

[0012] The present invention has the following beneficial effects compared with the prior art: The self-circulating waste heat recovery method for the production of graphite electrodes provided by the present invention, through the efficient heat storage and release characteristics of the phase change material, during the cooling process of the graphitization furnace, effectively stores the released high-temperature heat, and under appropriate conditions, recycles it for other industrial processes or energy reuse, thereby reducing energy waste, shortening the cooling time, and improving production efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 It is a schematic structural diagram of the self-circulating waste heat recovery device for the production of graphite electrodes of the present invention; Figure 2 It is a schematic diagram of the heat exchange of the phase change material in the closed container of the self-circulating waste heat recovery device of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0014] The present invention will be further described below with reference to the drawings and embodiments.

[0015] Please refer to Figure 1 , the self-circulating waste heat recovery method for the production of graphite electrodes provided by the present invention specifically includes the following steps: S1) Heat energy absorption: In the cooling stage of the graphitization furnace, a closed container 2 is placed in the high-temperature area of the furnace. The container is filled with a phase change material, and the melting point of the phase change material is higher than 600 °C, which is suitable for the high-temperature environment of the graphitization furnace. When the furnace temperature reaches or exceeds the melting point of the phase change material, the material changes from solid state to liquid state, absorbing and storing a large amount of heat.

[0016] S2) Heat energy storage: The heat absorbed by the phase change material is stored in the liquid material, and the closed structure of the container ensures that the heat will not be quickly dissipated. This process effectively stores the high-temperature heat in the graphitization furnace, creating conditions for subsequent utilization.

[0017] S3) Heat energy release: The container is cooled by an active cooling device. The cooling device can be air cooling or liquid cooling. During the process of reducing the temperature, the phase change material solidifies back into a solid state and releases the heat absorbed before.

[0018] S4) Thermal energy reuse: The released heat is guided to other processes that require thermal energy through a heat exchange device, such as preheating the kiln feed or providing a heat source for other processes. Through this step, the heat is effectively reused, forming a self-circulating system that continuously improves energy efficiency during the production of graphite electrodes.

[0019] By adopting the above technical solution, a self-circulating waste heat recovery method for the production of graphite electrodes according to the present invention forms a self-circulating and efficient system during the waste heat recovery process of the graphitization kiln, which not only significantly improves the energy utilization efficiency, but also shortens the cooling time of the kiln, and at the same time provides additional energy supply, helping to improve the overall production efficiency.

[0020] Preferably, in the thermal energy absorption step, the closed container 2 used is made of high-temperature resistant materials, such as tungsten-based alloys, tantalum-based alloys, rhenium-based alloys, molybdenum-based alloys, etc. These materials can all withstand an ambient temperature of up to 3000 °C, so as to ensure that the container will not deform or be damaged in the high-temperature environment of the graphitization kiln. The phase change material inside the container can be a high-temperature metal alloy (such as sodium-potassium alloy, magnesium-aluminum alloy, and copper-aluminum alloy, etc.) or inorganic salts (such as lithium carbonate, calcium chloride, and potassium nitrate, etc.) with a melting point between 600 °C and 1000 °C to adapt to the working temperature of the graphitization kiln. The number of the closed containers 2 is multiple, arranged in an equidistant array and attached to the graphite insulation layer 4 of the graphitization kiln.

[0021] Please continue to refer to Figure 2 , as a preferred embodiment, the closed container 2 of the present invention includes a tube shell 21 and an end cap 22 that are hermetically connected. A phase change material is provided as the working medium 23 inside the tube shell 21; the area of the tube shell 21 in contact with the hot fluid is the evaporation section 24, and the area of the tube shell 21 in contact with the cold fluid is the condensation section 25; an adiabatic section 26 is provided between the evaporation section 24 and the condensation section 25. By adopting the above technical solution, the high-temperature heat of the kiln can be effectively absorbed and stored, forming a self-circulating thermal energy recovery system.

[0022] Preferably, in the thermal energy storage step, the closed container 2 is designed to have a good sealing performance to prevent leakage of the high-temperature liquid phase change material during storage. A layer of high-efficiency thermal insulation material is coated on the outside of the container to reduce heat dissipation and ensure long-term storage of thermal energy.

[0023] By adopting the above technical solution, the heat in the graphitization kiln can be maximally retained, providing guarantee for subsequent thermal energy release and reuse, and ensuring the self-circulating operation of the system.

[0024] Preferably, in the heat release step, the cooling device 3 precisely adjusts the cooling rate through an automatic control device, causing the phase change material to slowly solidify under low-temperature conditions and release the previously stored heat. Meanwhile, the heat energy utilization is optimized to prevent thermal stress problems and extend the service life of the system. The cooling device 3 can select an air cooling, liquid cooling, or hybrid cooling system combining multiple cooling methods according to needs to achieve efficient heat release and control. Preferably, the cooling rate is 30 - 60 °C / h. If the cooling rate is too high, the subsequent temperature difference becomes smaller, and the cooling speed suddenly decreases, prolonging the overall cooling duration. If the cooling rate is too low, the effect is limited.

[0025] By adopting the above technical solution, the heat release process can be controlled in an optimal state, realizing precise reuse of heat and promoting the efficient operation of the self-circulating waste heat recovery system.

[0026] Preferably, in the heat energy reuse step, the released heat is transferred to other processes requiring heat energy through a heat exchange device, such as preheating the feed of a graphitization kiln, supplying other equipment, or used for power generation. The heat exchange device should be designed with high heat conduction performance to ensure maximum utilization of the released heat.

[0027] By adopting the above technical solution, the recovered heat can be efficiently transferred to other processes requiring heat sources, thereby improving the overall energy utilization rate and ensuring the continuous and efficient operation of self-circulating waste heat recovery during the production process of graphite electrodes.

[0028] A specific embodiment is given below.

[0029] Heat absorption: During the cooling stage of the graphitization kiln, a closed metal container is placed in the high-temperature area of the kiln. The container is made of a high-temperature resistant alloy and filled with an inorganic salt phase change material with a melting point of 800 °C inside. When the kiln temperature exceeds 800 °C, the material changes from solid to liquid, absorbing the high-temperature heat released by the kiln.

[0030] Heat storage: The liquid phase change material stores the absorbed heat in the container, and the container is coated with an efficient heat insulation material to ensure that the heat does not dissipate quickly. This step continues until the kiln cools down to a predetermined temperature.

[0031] Heat release: When the kiln cools down to 500 °C, the cooling device 3 is started to cool the container. The cooling device 3 adopts a liquid cooling method and adjusts the cooling rate through an automatic control device to ensure that the phase change material slowly solidifies and releases the stored heat.

[0032] Heat energy reuse: Through the heat exchange device 1, the released heat is conducted to the preheating system of the graphitization kiln for preheating the kiln feed, or the heat is introduced into other equipment in the factory area to realize the reuse of heat energy.

[0033] Effect analysis: By adopting the method of the present invention, in practical applications, the cooling time of the kiln is reduced by 30%, the energy utilization efficiency is increased by 20%, and at the same time, the process of heat energy reuse also provides stable heat source support for other equipment in the factory area. This self-circulating waste heat recovery system significantly improves the overall efficiency of graphite electrode production and effectively reduces energy waste.

[0034] Compared with the traditional cooling method of the graphitization furnace, the present invention has the following advantages: (1) The phase change material of the present invention absorbs and stores heat under high temperature conditions, and can maximize the recovery of waste heat from the graphitization kiln. By adopting the above technical solution, most of the heat energy can be stored and utilized, reducing the directly dissipated heat; (2) Through the cooling process optimized based on the phase change material, the method of the present invention significantly shortens the cooling time of the kiln. By adopting the above technical solution, the temperature of the materials in the kiln can be reduced more quickly, reducing the discharging time; (3) The stored heat can be used for various industrial purposes, including preheating, power generation, etc., further improving the energy utilization rate. By adopting the above technical solution, the recovered heat is effectively distributed to other processes that require heat sources, realizing the comprehensive utilization of energy.

[0035] Although the present invention has been disclosed above with preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some modifications and improvements without departing from the spirit and scope of the present invention. Therefore, the protection scope of the present invention shall be defined by the claims.

Claims

1. A self-circulating waste heat recovery method for graphite electrode production, characterized in that, It includes the following steps: S1) Heat energy absorption: In the cooling stage of the graphitization furnace, a closed container filled with a phase change material is used to collect high-temperature waste heat. S2) Heat energy storage: The phase change material absorbs heat at high temperature and transforms into a liquid state to store heat energy. S3) Heat energy release: A cooling device is used to cool the closed container, so that the phase change material solidifies again and releases the stored heat. S4) Heat energy reuse: The cooling device absorbs the heat released by the phase change material, and realizes waste heat utilization through a heat exchange device.

2. The self-circulating waste heat recovery method for graphite electrode production according to claim 1, wherein The phase change material is a high-temperature metal alloy or inorganic salt material with a melting point between 600°C and 1000°C.

3. The self-circulating waste heat recovery method for graphite electrode production according to claim 2, characterized in that The high-temperature metal alloy is sodium-potassium alloy, magnesium-aluminum alloy or copper-aluminum alloy.

4. The self-circulating waste heat recovery method for graphite electrode production according to claim 2, wherein The inorganic salts are lithium carbonate, calcium chloride or potassium nitrate.

5. The self-circulating waste heat recovery method for graphite electrode production according to claim 1, wherein The material of the closed container is tungsten-based alloy, tantalum-based alloy, rhenium-based alloy or molybdenum-based alloy.

6. The self-circulating waste heat recovery method for graphite electrode production according to claim 5, characterized in that, The outside of the closed container is coated with a heat insulation layer.

7. The self-circulating waste heat recovery method for graphite electrode production according to claim 1, wherein, The number of the closed containers is multiple, and they are arranged in an equidistant array and fitted with the graphite insulation layer of the graphitization furnace.

8. The self-circulating waste heat recovery method for graphite electrode production according to claim 1, wherein, The cooling device adopts air cooling, liquid cooling or hybrid cooling methods, and is provided with an automatic control device for adjusting the cooling rate between 30 - 60°C / h.

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