Rotary vane vacuum pump in vacuum furnace
In the production of industrial steelmaking, roots pump, water ring pump, rotary vane pump and steam jet pump are the most commonly used vacuumizing equipment, among which rotary vane vacuum pump and steam jet pump are the most common ones. Then various vacuum refining technologies began to appear, such as vacuum ingot method, ladle trickle degassing method, ladle degassing method, etc., which created the industrial scale vacuum treatment method of molten steel, especially the emergence of rotary vane vacuum pump, which accelerated the development of vacuum steelmaking technology. This paper mainly describes the application of a rotary vane vacuum pump in a vacuum furnace.
Rotary vane vacuum pump in vacuum furnace of application
Vacuum pump is one of the necessary equipment of vacuum refining equipment. Its pumping capacity, pumping rate and other process parameters directly affect the normal operation of vacuum and metallurgical effect.
Vacuum system equipment is a kind of secondary refining equipment used to produce high quality steel. The whole metallurgical reaction of molten steel is carried out in a vacuum tank with refractory lining. The lower part of the vacuum tank is two impregnated pipes with refractory lining, and the upper part is equipped with hot bends. The extracted gas is discharged to the outside of the plant from the hot bend to the vacuum pump system through the gas cooler.
Before the molten steel treatment, immerse the immersion tube into the molten steel to be treated. When the vacuum tank is vacuumized, the atmospheric pressure on the surface of the molten steel forces the molten steel to flow into the vacuum tank from the immersion tube (when the vacuum tank is about 0.67mbar, the molten steel can rise 1.48m in height). Two immersion tubes connected with the vacuum tank, one is a rising tube and the other is a falling tube. As the rising tube continuously blows argon into the liquid steel, a higher static pressure difference is generated compared with the falling tube without argon blowing, which makes the liquid steel enter from the rising tube and flow to the falling tube through the lower part of the vacuum tank, so the circulation is repeated. In the vacuum state, argon, hydrogen, carbon monoxide and other gases flowing through the vacuum channel water are pumped out in the process of liquid steel circulation. At the same time, a series of metallurgical reactions, such as carbon and oxygen reactions, are carried out for the molten steel entering the vacuum tank, so that the molten steel can be purified by the cyclic degassing refining.
The advantages of the vacuum treated molten steel are obvious: the alloy does not react with the slag basically, and the alloy is directly added into the molten steel, with high yield; the molten steel can be quickly and evenly mixed; the alloy composition can be controlled in a narrow range; the gas content is low, the inclusions are small, and the purity of the molten steel is high; the temperature of the chemical temperature rise can also be adjusted with the top gun to provide the continuous caster with good fluidity and purity The molten steel with high casting temperature is suitable for continuous casting of multiple furnaces.
This paper introduces the application of the rotary vane vacuum pump in the vacuum furnace, and focuses on the operation of the rotary vane vacuum pump and its metallurgical effect. The production practice shows that the metallurgical effect of the rotary vane vacuum pump applied to the vacuum furnace can reach or be superior to the same process index of the vacuum system of the multi-stage steam jet pump. The rotary vane vacuum pump is driven by electric energy. Its operation is not restricted by steam pressure and temperature. It can start and stop the pump at any time according to the actual production situation, and the production organization is flexible.
Vacuum pump technology and equipment are applied to the vacuum furnace process, which improves the air extraction capacity, decarbonization capacity, dehydrogenation capacity and molten steel circulation rate of the vacuum furnace. The operation of vacuum pump system is stable, energy saving and environmental protection, greatly reducing the production cost of vacuum process.