Air separation unit system classification

Lean alloy steel is often used in special pressure-bearing equipment. The alloying elements often added include manganese, silicon, chromium, nickel, molybdenum, vanadium, boron and rare earth elements. Most of silicon and manganese melt into ferrite, only a small amount into cementite, which are commonly used strengthening elements in lean alloy steel. The amount of chromium and nickel is generally small, and the main role of chromium and nickel is to increase the undercooling degree of austenite and refine the microstructure. Part of chromium is dissolved in ferrite and some in cementite, which can improve the stability of cementite. Molybdenum is dissolved in ferrite slightly, and has the effect of solid solution strengthening. It is a strong carbide forming element, which can improve the high temperature strength of steel and improve the temper brittleness.

During the start-up phase, when the liquid volume accumulates in the condensing evaporator, the gas and liquid mixture will pass through the liquid air and liquid nitrogen throttle valves. When the throttle valve begins to close, due to the large opening of the valve, when the amount of gas and liquid mixture from the lower column to the upper column changes little, and the pressure of the lower column does not increase significantly, it means that the temperature difference of the condensing evaporator has not increased. At this time, the condensing evaporator and the surrounding insulation have been cooled to the low temperature required by the liquid accumulation stage. Due to a large amount of cold production and a large amount of gas liquefaction, the liquid evaporation in the condensing evaporator is also increased. The rising steam produced prevents the flow of liquid from the sieve plate hole, and gradually accumulates liquid on the tray, so the liquid level will drop. In ad