The smoke and dust generated during the smelting of scrap steel in intermediate frequency furnaces have always been difficult to manage due to their complex identities, accompanying open flames, flammable dust, and other factors. In response to the complex working conditions of intermediate frequency furnace scrap steel smelting, this article comprehensively expounds and discusses the reform of traditional pulse bag dust removal technology, and solves the difficulties of smoke and dust management mentioned above, which has significant economic and social benefits.

The current situation of atmospheric smoke and dust pollution in the sea is rapidly increasing with the industrial movement, and smoke and dust pollution is becoming increasingly severe. The particles with a diameter of less than 2.5 microns and over 2.5 microns formed by industrial smoke, dust, construction dust and other pollutants have become the main pollutants in China at present. The haze weather is affecting people's lives. The large-scale haze weather has triggered multiple traffic accidents, and the number of patients in major hospitals such as respiratory surgery and allergen testing departments in urban areas has skyrocketed several times. It is necessary to manage the dust of some small steel kilns under the pretext of eliminating large-scale pollution such as steelmaking and power generation.

At present, the dust removal process for the smelting of intermediate frequency furnace scrap steel in China mainly includes cyclone dust collectors, hemp stone water film dust collectors, positive pressure back blowing large bag dust collectors, etc. Various dust collectors are explained as follows:

1) The dust removal efficiency of the cyclone dust collector is not high, and it has low effectiveness in capturing fine dust with a particle size less than 5um and dust with low particle density. It occasionally fails to meet the requirements for dust containing gas emission concentration in small-scale applications. Because the smoke and dust generated during the smelting of scrap steel in intermediate frequency furnaces have a light density and small particles, the effectiveness of this type of dust collector is even lower than that of abnormal cyclone dust collectors.

2) The entire Ma Shi water film dust collector is made of natural granite masonry, which is resistant to acid, corrosion, wear, and has a long service life. The dust removal efficiency of the Ma Shi water film dust collector may reach over 98%. However, in terms of the characteristics of dust generated during the smelting of scrap steel in medium frequency furnaces, although the sand stone water film dust collector has higher dust removal efficiency than the cyclone dust collector, it still cannot reach the emission scale of smoke and dust; The water carrying performance, secondary pollution performance, and anti freezing performance of other granite water film dust collectors' fans make it much more difficult to apply and protect them in practical operation.

3) Positive pressure back blowing large bag filter is one of the earliest forms of bag filter. Positive pressure back suction bag filter is cost-effective and easy to operate. The glass fiber filter material selected for this dust removal equipment has the advantages of high temperature resistance, low cost, and long service life. The problem is that the filter bag of the positive pressure dust collector has a high air permeability and cannot capture smaller particles; The overall air leakage rate of other positive pressure dust collectors is relatively high, and there is a significant phenomenon of dust and smoke overflow from the fan casing and dust collector casing; The fan causes significant wear and tear before the dust collector.

Since its introduction in the 1950s, the pulse bag filter, a new process for managing smoke and dust in the smelting of scrap steel in medium frequency furnaces, has been widely used and continuously improved at home and abroad, and has made great progress in polluting dusty gases. The dust cleaning technique is advanced, the air to cloth ratio has greatly improved, and it has the characteristics of large air volume disposal, small footprint, high pollution efficiency, reliable work, simple layout, and small maintenance volume. The dust removal efficiency can reach over 99%, making it a mature and perfect high-efficiency dust removal equipment. Pulse bag filter is the most ideal dust removal method for managing the flue gas of intermediate frequency furnace scrap steel smelting. The following are the actual achievements and solutions of the dust collector in the management of waste steel smelting dust in intermediate frequency furnaces:

1) Currently, the smoke and dust generated during the smelting of medium frequency furnaces in China are mainly captured by top suction hoods, which have a large amount of capture air; The distance between the suction ports and the dust generation points is relatively far, and the thermal lift force of the flue gas is not strong; The ventilation of the factory building is affected by lateral winds, resulting in a low smoke network rate; The top suction hood also affects the operation of feeding and steelmaking.

Based on the above results, we have planned a cantilever mobile semi closed dust collection hood. On the basis of the umbrella shaped cover, a low hanging cover is installed, and a twisting and moving assembly is installed on the main pipeline. In this way, the vacuum hood is less affected by lateral wind, and its effectiveness in capturing smoke is high, and the necessary air volume is not large. Other cantilever movable semi closed dust hoods can be moved away to leave space for it during operations such as feeding and steelmaking, making them lightweight and applicable.

2) The dust in the flue gas has a complex identity and is often accompanied by open flames. Steel mills that usually adopt medium frequency furnace steelmaking are mostly small enterprises with absolutely backward technology. The raw materials they construct are mostly light scrap steel, which has too many non-metallic identities and generates a large amount of smoke when adding materials. Other furnace materials are often mixed with recycled materials and waste materials, and the proportion of oil and oxides in the waste is relatively high. This is because during the smelting process, the smelting flue gas has a complex identity, high dust content, and is accompanied by a large number of open flames. The open flames entering the dust collector may also cause the extinguishing of other dust in the dust collector. These achievements are all difficulties that constrain the application of bag filters. The following are the steps taken to improve the actual process:

a. Install a mixing valve at the front end of the dust collector, extend the spacing between the dust removal pipes, and increase the number of bends in the pipes. After excessive cool air is mixed into the system, the oxygen brought in will promote the complete extinguishing of dust in the flue gas, which will be sufficiently extinguished; Then, through the collision of the bends of the dust removal pipeline during the passage of time, the ignited particles of dust are burned out.

b. In the past, folded plate gravity settling chamber was added to the dust remover, and spray assembly was added. After some particles with fire are extinguished, they are atomized by spray assembly before entering the dust remover to cool the remaining particles with open fire, reduce the specific gravity of dust particles, make them fall when they pass through the folded plate gravity settling chamber, and prevent them from entering the pulse bag dust remover.

c. When planning a pulse bag filter, it is necessary to seal it as much as possible to reduce air leakage and oxygen content inside the filter. High temperature resistant fiberglass needle punched felt bags should be selected.

3) It is difficult to clean the dust in the dust collector, and the secondary dust emission results. In addition to the complex identity, high dust content, and large amount of open flames accompanying the waste steel smelting flue gas in the intermediate frequency furnace, another characteristic of the flue gas is its small particle size and light density. The dust entering the dust collector separates into bags when blown, but does not fall into the ash hopper. After the cleaning stops, it adheres to the bags again, causing high resistance in the dust collector.

Therefore, when selecting a dust collector for waste steel smelting flue gas management in a medium frequency furnace, the filtering area of the dust collector should be large and the filtering wind speed should be low; At the same time, the pulse bag filter should use offline dust cleaning, and the offline time should be absolutely longer. The filtering wind speed of the dust collector should not exceed 0.8m/min, and the offline time should not be less than 3 minutes.

4. Economic analysis: The smoke and dust management network for intermediate frequency furnace scrap steel smelting has a market price of approximately 2000 yuan per ton of dust; The dust collection capacity of a pulse bag filter is at most twice that of other dust removal methods. A pulse dust collector can collect dust for more than 2 years, which is equivalent to the price of a set of equipment.

5. Conclusion 1) The smoke generated during the production process of intermediate frequency furnace scrap steel is greatly persecuted, and it is necessary to stop complete management of it.

2) From the economic benefits generated by accepting and taking over dust, it can be seen that the investment in the new process of pulse bag filter is legitimate.

3) The dust removal project not only improves the living and labor conditions in the factory and surrounding areas, reducing the harm caused by pollution to the human body, but also improves the labor conditions, improves the effectiveness of labor, and reduces the loss caused by dust during labor. The direct benefits are enormous.

4) The pulse bag filter, combined with a new process, is undoubtedly the most ideal dust removal method for the management of waste steel smelting flue gas in intermediate frequency furnaces. Its dust removal efficiency is extremely high, the capture capacity is strong, the operation is stable, and it is economically applicable.