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Energy saving and consumption reduction in the electric arc furnace smelting process has always been a major research topic. During the smelting production process of electric furnaces, a large amount of high-temperature dust-containing flue gas is produced. The flue gas temperature is as high as about 1300°C, the dust content is about 10g/m3, and the exhaust volume in the furnace is about 500~1200m3/h. t, the sensible heat of high-temperature flue gas accounts for about 20% of the total energy consumption. Obviously, recovering the sensible heat of flue gas will produce huge economic benefits. During the smelting process, the flow rate, temperature and dust content of the flue gas are constantly changing. Among them, the flue gas temperature during the oxidation period is the highest, the flow rate is the largest, and the dust content is the largest. ； During the tapping period, the flue gas temperature is the lowest, the flow rate is the smallest, and the dust content is also the smallest. The periodic changes in flue gas parameters bring certain difficulties to the waste heat utilization of flue gas. 1. There are two commonly used sensible heat recovery methods for electric furnace flue gas.: Preheat scrap steel and use waste heat boilers. After the flue gas sensible heat preheats the scrap steel, the flue gas temperature is still as high as about 1000°C. In actual production, the waste heat resources of this part of the flue gas have not been utilized and wasted in vain, resulting in huge waste of energy. On the basis of full demonstration, Tianjin Huaneng Group Energy Equipment Co., Ltd. used the high-tech "heat pipe" to develop the country's first electric arc furnace heat pipe waste heat boiler device. It was successfully put into production on November 21, 2006 in a 30-ton electric arc furnace at the Shandong Laigang Group Machinery Factory. The test run was successful once, and it has been operating normally and has achieved significant economic benefits. 2. Electric arc furnace smoke exhaust system The smoke exhaust system of the 30t electric arc furnace of Shandong Laigang Group Machinery Factory. The flue gas comes out of the electric arc furnace and flows through the sliding sleeve into the settling chamber. After pre-dusting, it enters the water-cooled flue and water spray cooler to reduce the exhaust gas temperature to below 250°C. After entering the bag dust collector for efficient dust removal, it is discharged into the atmosphere through the chimney by an induced draft fan. The furnace smoke exhaust system has the following deficiencies:: (1) The waste heat of the high-temperature flue gas up to 1300°C coming out of the furnace has not been utilized, resulting in serious waste. (2) The flue gas temperature is too high and the bag will be burned. (3) The dust removal efficiency is not high and the dust discharge exceeds the standard. 3. Based on the current dust removal process, Tianjin Huaneng Group Energy Equipment Co., Ltd. studied the characteristics of dust in exhaust smoke and combined with heat pipe technology to design a heat pipe waste heat boiler that is not easy to accumulate dust to replace the mechanical cooling or water spray cooling in the traditional dust removal system. The flue gas temperature is reduced to 200°C, and the waste heat in the flue gas is fully recovered to generate saturated steam, which can be used in enterprise production and life. At the same time, a better ash removal plan is provided to ensure that the flue gas discharge temperature meets the allowable operating temperature of the bag dust collector while recovering the waste heat. And it operates stably for a long period of time. 1. Heat pipe technology and working principle (1) Heat pipe is a new type of efficient heat transfer element. According to a more precise definition, it should be called a "closed two-phase heat transfer system", that is, a device that transfers heat in a closed system that is evacuated and relies on the phase change of the fluid inside (liquid to vapor and vapor to liquid). In recent years, heat pipe technology has developed rapidly. Due to its advantages of fast heat transfer, high thermal efficiency, and low operation and maintenance costs, it is widely used in various fields of waste heat recovery. (2) The heat transfer principle of a heat pipe is to evacuate a closed tube shell and fill it with a certain proportion of liquid working medium (working fluid) to form a heat pipe. The heat pipe placed in the heat source part is called the evaporation section (hot end), and the heat pipe placed in the cooling part is called the condensation section (cold end). When the evaporation section absorbs heat and transfers heat to the working fluid, the working fluid absorbs heat and changes from liquid to gas, undergoes phase change, and absorbs the latent heat of vaporization. Under the action of the pressure difference in the tube, the gas carries latent heat and flows from the evaporation section to the condensation section, transferring the heat to the cold fluid outside the tube and releasing the latent heat of condensation. The working medium in the tube condenses from gas to liquid. Under the action of gravity, it returns to the evaporation section and continues to absorb heat and vaporize. In this way, heat is continuously transferred from the hot fluid to the cold fluid. (3) Characteristics of heat pipes ① The thermal conductivity rate of metal and non-metal materials depends on the thermal conductivity of the material, the temperature gradient, and the cross-sectional area orthogonal to the temperature gradient. Taking metallic silver as an example, its value is about 415W/mK. It has been measured that the thermal conductivity of the heat pipe is hundreds to thousands of times that of silver, so the heat pipe is called a superconductor. ②Since the heat transfer process in the heat pipe is a phase change process and the purity of the working fluid is very high, the temperature of the steam in the heat pipe is basically maintained at a constant temperature.: The temperature difference between the two ends of the heat pipe does not exceed 5°C. Compared with other heat transfer elements, the heat pipe has good isothermal performance. ③The temperature range that the heat pipe can adapt to is related to the specific structure of the heat pipe, the working fluid used and the ambient operating temperature of the heat pipe. At present, the temperature range that heat pipes can adapt to is generally -200°C to 2000°C, which is also difficult to achieve by other heat transfer elements. ④Even if some heat pipes are damaged during operation, the two heat exchange media will not be mixed, and there is no need to stop the machine to plug the leak. Therefore, heat pipe equipment has the advantages of long service life, safety and reliability. ⑤Since each heat pipe is an independent heat exchange element, no matter how big or long it is, each heat pipe can be replaced at will and has high replacement performance. 2. The structure and principle of heat pipe waste heat boilers. Heat pipe waste heat boilers are available in vertical and horizontal types and can be designed according to site conditions. It is mainly composed of three parts: heat pipe soft water heater, heat pipe boiler, and heat pipe economizer. The heat pipe is arranged in longitudinal fins and circumferential fin cross rows. The flue gas and water complete the heat transfer through the heat pipe to generate saturated steam. This structural form is not prone to dust accumulation. 4. Dust removal method of heat pipe waste heat boiler Since the flue gas of the electric furnace contains a large amount of dust, for example, the production of 1 ton of steel will produce 6-8kg of dust. Therefore, when the equipment is running for a period of time, dust accumulation will occur, affecting the normal operation of the entire system. According to the specific characteristics of the equipment, At this point, we adopt the method of gas shock wave soot blowing, equipped with an acetylene station and a gas shock wave soot blowing system. When the boiler system resistance reaches the set value, the soot blowing system starts, purges first, and then blows soot in reverse direction, starting from the end of the equipment and blowing forward in sequence, and then blowing from front to back. The strong impact force generated by gas deflagration is used to blow off the dust attached to the fins. Part of it is taken away by the flue gas, and part of it falls into the ash hopper and is discharged by the ash conveying system. Gas shock wave soot blowing is simple and practical, and the effect is obvious. 5. Electric arc furnace waste heat recovery process l 300°C high-temperature flue gas flows from the sliding casing into the settling chamber (combustion chamber), where pre-dusting and CO removal are performed. The 1200°C flue gas enters the water-cooled flue, and is further cooled to 850°C and enters the heat pipe water softener. Here, the 20°C soft water is heated to 104°C and enters the thermal deaerator. After the flue gas is further cooled, it enters the heat pipe waste heat boiler to generate high-pressure saturated steam. After the flue gas enters the heat pipe economizer, the deoxygenated soft water is heated from 104°C to 200°C and enters the vapor-liquid separator (steam drum). The flue gas drops to 200°C and enters the bag dust removal system. The high-pressure saturated steam is sent to the regenerator and turned into low-pressure steam for continuous use in production, life or low-pressure power generation. Production practice shows that the heat pipe waste heat recovery system has advanced technology and reasonable design, and has the characteristics of smooth operation, convenient operation, safety and reliability, significant energy saving, smooth steelmaking, and short investment recovery period. The successful development of the heat pipe waste heat recovery system has opened up a new way for the utilization of waste heat from electric arc furnaces and made new contributions to the technological progress of the metallurgical industry. Tianjin Huaneng Group Energy Equipment Co., Ltd. is a high-tech enterprise in Tianjin developed by science and technology. It currently has 550 employees, including 91 with a college degree or above, 12 senior engineers and 22 engineers. The annual sales revenue is 150 million yuan. In 1990, the Chinese Academy of Sciences introduced the high-tech "heat pipe" and used it as a leader to continuously innovate and develop dozens of new energy-saving equipment. One of the results obtained * * The title of first-class new product, four achievements won the first, second and third prize of Tianjin Science and Technology Progress Award, and three achievements were achieved. * * patent. In 2000, the Tianjin Municipal Science and Technology Commission named it "Tianjin High-tech Enterprise", and in 2001, it passed the "ISO9001 International Quality System Certification". Our company wholeheartedly welcomes scientific research institutes and enterprises to visit, consult and cooperate. Contact person: Zhang Guohua’s phone number: 13342058156