When acetylene or hydrocarbons accumulate in the local area of the main cooling system, explosion may occur under certain conditions. When this kind of slight explosion occurs, there is no external response and no sound, so it is often imperceptible at first. Only when the oxygen purity changes automatically and cannot be adjusted, can this happen.DEAR Cryogenic air separation unit.In the liquid accumulation stage of start-up, the heat load of condensing evaporator is usually reduced by properly increasing the upper tower pressure and reducing the temperature difference of condensing evaporator, so as to accelerate the accumulation of liquid. The average temperature difference between long tube and plate fin condensing evaporators is usually 1.6 ~ 1.8 ℃. In normal operation, the temperature difference of condensing evaporator is basically constant.DEAR Cryogenic air separation unit.During the start-up of the oxygen generator with intermediate extraction process, if the intermediate extraction temperature drops very slowly, the operation will be difficult. The reason is that the heat capacity of pebble is large and the heating temperature is too high.
DEAR Cryogenic air separation unit.When the air pressure suddenly decreases, close the water supply valve (or stop the pump) of the air spray cooling tower as soon as possible. If the pressure of the air separation system can not be restored temporarily, the valve of the air inlet device shall be closed as soon as possible. Before the air supply is not stable, water is generally not supplied, so as to avoid pressure fluctuation and increase the amount of water carried by the air.According to the working pressure, it can be divided into high pressure device with pressure of 10.0 ~ 20.0Mpa, medium pressure device with working pressure of 1.0 ~ 5.0mpa and full low pressure device with pressure of 0.5 ~ 0.6MPa. The classification method is artificial, there can be other classification methods.In practical operation, the temperature balance between two groups is mainly adjusted according to the temperature difference in the middle of two groups of cold accumulators or two groups of switching heat exchangers. The middle temperature difference between groups is generally controlled within 10 ℃. In addition, the actual control in the operation is often the temperature of the air at the outlet of the circulation or the middle outlet, no matter whether it is the actual middle temperature or not.
The temperature of expander can also be regulated by bypass air (low temperature air at the outlet of heat exchanger). In a word, as long as the temperature difference at the hot end is controlled and the intermediate extraction temperature is within a certain range, the working condition of the non switching plate fin heat exchanger is basically stable. Even if there are some changes, as long as the cooling capacity can be balanced, there is no need to make more adjustments.DEAR Cryogenic air separation unit.When operating the steam heater, pay attention to: always check the condensate water level of the steam heater. High water level will affect the temperature of heat exchange; when the steam heat exchanger leaks, it will affect the effect of heating regeneration. Therefore, the moisture content in the gas after heat exchange should be checked frequently. Generally, the moisture content should be less than 1 × 10-6 (dew point temperature - 65 ℃).DEAR Cryogenic air separation unit.The amount of pure liquid nitrogen supplied by the lower tower to the upper tower is less, so a stream of dirty liquid nitrogen can be extracted to the upper tower, which increases the reflux ratio of the upper tower distillation section and has greater distillation potential, so as to allow more expanded air to enter the upper tower, so as to prevent the bypass of expanded air and affect the oxygen extraction rate.
