There are many types of refining equipment outside the furnace.VD/VOD (Vacuum Refining Furnace) smelting steel in a vacuum environment, the whole process of blowing argon stirring, reduce the partial pressure of impurity gases in the steel to reduce the hydrogen, oxygen, nitrogen content in the steel to improve the quality of the steel, and in addition to blowing into the steel in a vacuum environment of oxygen to reduce the carbon content of the steel and maximize the assurance of chromium in the steel will not be oxidized. According to the structure type, there are two kinds of tank cover type and tank car type, and the tonnage of the furnace is from 10 tons to 160 tons. AOD (full name: Argon Oxygen Decarburization) is the abbreviation of Argon Oxygen Decarburization refining method, blowing oxygen decarburization to the steel at atmospheric pressure, while blowing into the argon (or nitrogen) in order to reduce the partial pressure of carbon monoxide decarburization during the period of the partial pressure of carbon monoxide, to achieve the de-carbonization of chromium protection at a more reasonable temperature, mostly used in the refining of high-chromium stainless steel, the furnace tonnage of 10 tons to 90 tons.