In the past, steel mills used steam jet pumps because of their high pumping speed and low short-term investment. But now, steel manufacturers want to take a different way to Iron steel degassing. In order to make better use of the advantages of vacuum pump in degassing application, such as high efficiency, safety, environmental protection and low energy consumption, our company has sorted out some information about these contents for you.
Iron steel production process mainly includes: ironmaking, steelmaking, steel casting, rolling and other processes. Steelmaking is the removal of excessive carbon, sulfur, phosphorus and other impurities from raw materials (molten iron) and the addition of appropriate alloy components.
First of all, why choose vacuum pump for Iron steel degassing?
The first point is related to operating costs. Although the initial investment in the mechanical vacuum pump system used for degassing in steelmaking is usually higher than that of the injection system (without considering auxiliary equipment), the operating cost of the mechanical vacuum system is significantly reduced with the same pumping speed. So once the operating cost is included, the investment return of the dry vacuum pump system will be higher.
The second consideration is the auxiliary workshop cost. Steam injection systems require various auxiliary facilities, such as boilers, water-making equipment (water for preparation) and water-making equipment for wastewater. The maintenance of auxiliary equipment increases the burden of operation and investment.
Environmental sustainability is another issue to consider. Steam injection system, as its name implies, uses power steam to create the necessary vacuum for degassing process. Therefore, the process gas is mixed with steam and condensate water. Mud produced by mixing dust, process gas and steam must be treated in accordance with local environmental standards. Steelmakers are well aware that dust treatment is simpler and cheaper than slurry treatment. The mechanical vacuum system used for degassing is a dry system, so it has the advantage of not having to deal with expensive mud.
Low energy consumption and low carbon emissions are the further advantages of vacuum pump system over steam injection. Iron and steel mills are high energy-consuming enterprises. Even when steel stops degassing, the boiler of the steam jet pump system usually needs to run continuously. However, the mechanical vacuum pump system is controlled by a button, which only runs in the degassing process and generates energy consumption.
Gas in steel is harmful to steel performance in most cases. Hydrogen in steel can lead to white spot, cracking and other hazards. Nitrogen in steel can cause aging embrittlement of steel and reduce mechanical properties of steel. Therefore, gas in steel should be reduced to the lowest possible extent.
The advantages of vacuum pump applied in degassing of iron steel are as follows:
1. Vacuum degassing is effective. Because of the input of driving gas, a large number of bubble nuclei are formed in the riser tube, and the liquid steel entering the vacuum chamber is sprayed into tiny droplets, which greatly increases the surface area of liquid steel degassing, thus facilitating degassing.
2. Low temperature drop. Generally, the temperature drop of treatment is only 30 – 50 C, and electric heating can also be carried out during degassing, so the molten steel only needs a little overheating in the furnace.
3. The treatment range is large. The same equipment can handle different capacity of molten steel, and can also be used in electric arc furnace and induction furnace.