Air separation plant.The purpose of purging after heating the fractionator is to remove the mechanical impurities in pipes and vessels. The blowing out steps are as follows: the preparation before blowing out: close the main inlet valve of heating air and all heating valves, open the blowing out valve of oil-water separator of purifier at the same time, loosen the ejector rods of inlet and outlet valves of expander, close the on-6 valve, pull open the stem of joint-1 valve, open the blowing-1 valve, blowing-2 valve and high pressure gauge valve, and close the blowing out valve of oil-water separator of purifier;Air separation plant.The fluctuation of pressure in the upper and lower towers, the fluctuation of liquid oxygen level, and the change of purity of liquid oxygen and liquid nitrogen will affect the heat transfer temperature difference and heat load of the main condensing evaporator. The influence depends on how much the temperature difference of heat transfer deviates from the design value.
Air separation plant.There is no special requirement for oxygen purity in ironmaking. However, if a separate oxygen generation system is specially configured for ironmaking, it can not mix with oxygen for steelmaking, so it is still supplied by high purity oxygen system. Oxygen is generally inhaled from the blower inlet, so there is no requirement for oxygen pressure. Smelting reduction ironmaking. It uses coal to reduce iron ore. The oxygen purity is required to be more than 95%, and the oxygen consumption per ton of iron is 500-550m3 / T.Air separation plant.In fact, it is difficult to achieve isothermal compression in the compression process of air in the compressor. The temperature after compression is often higher than the ambient temperature when the air is inhaled. The enthalpy value H ′ 2 of the compressed gas may also be higher than the enthalpy value H 2 before compression. However, after throttling by the throttle valve, the temperature will still decrease and the enthalpy will remain unchanged.
Air separation plant.In the condensing evaporator, the liquid oxygen from the bottom of the upper tower is heated and evaporated by the gas nitrogen from the top of the lower tower, part of which is extracted as oxygen product, and part of which is used as rising gas to participate in the distillation of the upper tower; the gas nitrogen releases heat and condenses into liquid nitrogen, part of which is used as reflux to participate in the distillation of the lower tower, and part of which is throttled to participate in the distillation of the upper tower. This shows that the temperature of gas nitrogen is higher than that of liquid oxygen in condensing evaporator.Air separation plant.The circulating flow is a stream of backflow gas added in the cold section of the switched heat exchanger (or cold accumulator). Changing the circulating flow changes the proportional relationship between the positive and backflow gas flow in the cold section. With the increase of circulating air flow, the cooling capacity of the cold section increases relatively, which can cool the air to a lower temperature, so the air temperature at the cold end decreases and the temperature difference at the cold end decreases.
Air separation plant.When the temperature of positive flow air into the accumulator (the temperature at the hot end, which is related to the cooling effect of the last stage cooler of the air compressor or nitrogen water precooler) and the temperature of return flow air into the accumulator remain unchanged, the temperature difference between the hot end and the cold end of the accumulator is interdependent. If the temperature difference at the hot end is too large, the temperature difference at the cold end must be too small; if the temperature difference at the hot end is too small, the temperature difference at the cold end must be too large. This is determined by the balance of positive and return gas cooling capacity of the accumulator.Air separation plant.In order to check the perpendicularity next time, the shell of the tower (6-7m above the ground) is welded with a correction iron with a hole of 1 mm, the heavy vertical line is hoisted, the correction iron plate is welded at 150 mm above the ground, and a point is made on the correction plate at the vertical center for future inspection.
