Expander, freezer, air precooling system and argon purification system shall be shut down by interlocking. If there is no shutdown, it should be stopped manually; stop the delivery of oxygen, nitrogen and other products, stop the removal of liquid oxygen, liquid nitrogen and liquid argon; close the water valve connecting the air precooling system with the outside. The rest are operated according to the requirements of normal shutdown. After the above operation, find out the cause of the fault and prepare for restart.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.
DEAR Biogas purification unit.When the air quantity decreases, the rising steam quantity and reflux liquid quantity in the tower decrease, but the reflux ratio remains unchanged. Under normal conditions, it has little effect on the purity of oxygen and nitrogen products. According to the material balance, the output of oxygen and nitrogen will decrease when the air volume is reduced.DEAR Biogas purification unit.The operation condition of refined argon tower mainly depends on whether the condenser and evaporator work well together. If the cooling capacity of the condenser is too much, the condensation capacity is too large, and the reflux liquid is too much, the nitrogen part will not evaporate sufficiently, and the argon at the bottom may be polluted by nitrogen, thus reducing the purity of argon.DEAR Biogas purification unit.The central air extraction port of each accumulator in the central air extraction process of the accumulator enters the automatic valve box of the central air extraction through the central air extraction valve. When one of the cool accumulators in each pair flows with positive air, part of the air is extracted from the middle part, and then converges to the CO2 adsorber through the regulating-7 valve.
When parking, it is not easy to produce convection when it is cold at the bottom and hot at the top. The cold gas in the tower goes through low temperature first and then high temperature, so the cold loss is less. Its disadvantage is that the hot pipe is on the top, which is not convenient for pressure test. In addition, when the air cooling tower fails and the water enters the molecular sieve system, and then enters the plate fin heat exchanger, the water will enter the low temperature zone, so it is troublesome to heat and thaw.DEAR Biogas purification unit.The lower the pressure behind the expander, the greater the pressure drop in the expander and the greater the unit cooling capacity. However, due to the expansion of the gas into the distillation column, there is little room for pressure change. The higher the adiabatic efficiency of the expander, the greater the refrigerating capacity.In order to ensure self cleaning of all low pressure air separation unit, the temperature difference at the cold end of switching heat exchanger must be controlled within the allowable temperature range to ensure self cleaning. The self clearing temperature difference at the cold end is the difference between the temperature when the positive air passes through the cold end section and the temperature when the backflow gas passes through the section. In normal operation, the measured temperature difference at the cold end is the self clearing temperature difference.
