Abstract: In order to make the vacuum pump suction capacity can adapt to the degassing process to the greatest extent, the number of stirred gas, the surface of the equipment and the leakage rate of the equipment should be considered when choosing the vacuum pump. With the development of liquid steel vacuum treatment technology, it is an urgent problem to remove the gas in liquid steel efficiently. Due to the comprehensive factors such as dust and maintenance times, steam jet pump with large extraction capacity, strong operation reliability and simple structure should be adopted instead of mechanical pump. However, in recent years, due to the excessive pumping capacity of dry mechanical pump, high temperature and humidity, inflammable and explosive problems, spraying system is still used in the vacuum equipment of liquid steel vacuum treatment. Therefore, further research should be conducted on the selection, configuration, distribution and determination of compression ratio, temperature rise calculation, efficiency calculation, torque calculation and speed control of Roots pump in the future to solve practical problems.

Key words: liquid steel treatment, steam jet pump, roots pump, condenser