DEAR Air separation equipment.In normal operation, the temperature of intermediate extraction is - 110 ～ - 120 ℃. At this time, the water has been basically removed, the carbon dioxide is removed by the adsorber, and the air entering the expander will be a clean gas without water and carbon dioxide. However, in the initial stage of start-up, the accumulator is still in the cooling stage.In the case of slight water inflow and slight freezing, it can be treated without stopping. For example, shorten the switching time, increase the backflow ratio (the ratio of backflow gas to positive flow gas), or stop for a short time to carry out back blowing (low temperature or normal temperature dry gas is introduced from the heating inlet pipe of the sewage nitrogen pipe at the cold end and discharged from the hot end).DEAR Air separation equipment.The refrigerating capacity provided by the refrigerator is usually precooled by the low-temperature working medium of the refrigerator in the air separation unit purified by molecular sieve, so as to improve the adsorption purification effect. This is the cooling capacity provided by the outside of the air separation unit, which refers to the heat carried away by the chilled water from the air. It can reduce the required throttling effect and the cooling capacity of the expander.
DEAR Air separation equipment.During the pressure relief of molecular sieve switching operation, if the pressure relief is too fast, because the pressure relief valve is under the molecular sieve bed, the pressure in the lower part of molecular sieve can be relieved quickly, and the pressure above the molecular sieve bed can only be relieved through the molecular sieve bed.DEAR Air separation equipment.The common causes of flange leakage are that the sealing surface is not smooth and smooth, the pipeline compensation is insufficient, the bolts are not tightened evenly, and the bolt material is improper. Both ends of the outer screw sleeve of the valve stem are connected by tinned thread, which is easy to crack and leak after long-term use.DEAR Air separation equipment.The overall heating procedure in cold state is shutdown - liquid discharge - standing - cold blowing - heating - system blowing. The end point of heating is until the outlet temperature of heating gas reaches normal temperature. The overall heating operation procedure in hot state is divided into two steps: heating and blowing. In order to completely remove the moisture and achieve the purpose of drying, the outlet temperature of heating gas should be higher than normal temperature. In order to remove solid impurities, the blowing out process is more important in the overall heating operation under hot state.
DEAR Air separation equipment.The method of intermediate extraction is to open the ventilation and extraction valves for 4-5 turns, and then slowly open the regulating valve-7. A part of the air can be extracted from the middle, and combined with the low-temperature air from the ventilation valve-4 to enter the carbon dioxide adsorber. When the middle part can not be pumped out temporarily, it means that the resistance of the central extraction pipeline is large, the air only goes through - 2 valve and - 4 valve, and the automatic valve of the central extraction can not be opened.The higher the thermal conductivity is, the stronger the thermal conductivity is. The thermal conductivity of different materials is different. For the same material, it is also related to its structure, density, humidity, temperature, pressure and many other factors. Table 27 lists the approximate values of the thermal conductivity of some commonly used materials.Due to the impact of air flow, the actual content of carbon dioxide in the air at the cold end of the accumulator and the switching heat exchanger will exceed the saturation content, which will also affect the operation cycle. In particular, the cold section of the switching heat exchanger is too short, and the carbon dioxide precipitation zone is shortened, which makes it easier to bring part of carbon dioxide into the column, resulting in the increase of resistance of the distillation column, the weakening of main cooling heat transfer, the blockage of the subcooler, the increase of the down tower pressure, and the decrease of the air intake and oxygen output.
