There are two ways of blowing: continuous blowing and intermittent blowing. The so-called "continuous blowing" is the blowing method that the blowing valve is always open for a period of time. The so-called "intermittent blowing" means that the blowing valve is closed and opened when it is closed, and then it is suddenly opened after holding high pressure when it is closed and repeated. This method has a good effect on removing solid impurities and free water. Because the pressure difference increases when the pressure is held, the air flow speed increases when the blow off valve is opened, and the impact entrainment effect is enhanced.DEAR Air separation plant.In tube test of heat exchanger. Close the high pressure air throttle valve and the high pressure air inlet valve of the expander, install the high pressure gauge and open the valve. Open one blow off valve of the lower tower and one blow off valve of the upper tower, and the gas source is introduced from the blow off-2 valve. Open the blow off-1 valve to check whether the gas is discharged, and then close it. When the pressure of the heat exchanger rises to 1MPa, stop the air intake and check whether there is air leakage at the external connection.
The total refrigerating capacity QP (kJ / h) of the expander is related to the expansion capacity V (m3 / h) and the unit refrigerating capacity ah (kJ / KMOL): QP = V △ H / 22.4 = vaht · η P / 22.4, in which the unit refrigerating capacity △ ^ is equal to the product of the unit theoretical refrigerating capacity △ HT and the expander efficiency η P. The unit theoretical cooling capacity depends on the pressure before expansion, temperature and pressure after expansion.DEAR Air separation plant.The working temperature range of molecular sieve is generally 8 ~ 15 ℃, which can work normally. Once beyond this range, the loading capacity will increase, the adsorption effect will decrease, and even the adsorption effect will lose. When the chiller fails, the temperature of the air entering the molecular sieve adsorber increases.DEAR Air separation plant.After throttling, the pressure decreases, the mass specific volume increases, the distance between molecules increases, and the potential energy of molecular interaction increases. However, the flow energy generally changes little, so it can only be converted into potential energy by reducing the kinetic energy of molecular motion. The speed of molecular motion slows down, which is reflected in the decrease of temperature. In the air separation plant, throttling is the case, which is also the purpose of throttling cooling refrigeration.
DEAR Air separation plant.The liquid oxygen absorbs the latent heat of condensation released by the gas nitrogen with higher temperature and evaporates. So it is called "condensing evaporator". Condensing evaporator is an important heat exchange equipment in distillation system. Its working quality is related to the power consumption and normal production of the whole air separation unit. Therefore, it is necessary to correctly operate and maintain the condensing evaporator.DEAR Air separation plant.Before the appearance of liquid air, the flow rate of central pumping or circulation should be appropriate, and there should be considerable room for adjustment. Generally, the intermediate temperature should not be lower than - 100 ℃. Before and after the appearance of liquid air, cool the main engine thoroughly as soon as possible, so that liquid oxygen can appear as soon as possible after the appearance of liquid air. It will not evaporate quickly after throttling to the upper tower due to liquid air.
DEAR Air separation plant.When the group with small flow is moving air, the pressure of the main air pipe rises and the temperature in the middle part is low, which indicates that some automatic air valves are not opened. When some of the automatic valves are not opened, the pressure of the upper tower will rise and the temperature in the middle will be higher.The left half of the saturation curve is the saturated liquid line, the right half is the saturated vapor line, and the vertex is called the critical point. The region below the saturation curve is the wet vapor region, and the region is the mixture of gas and liquid, indicating that some of them are liquid.A cooler is added at the end of the turbine air compressor to reduce the air temperature below 100 ℃ before entering the spray tower. The packing ring and water separation device should be inspected, cleaned or replaced regularly. The maintenance of the liquid level self regulating device should be strengthened to ensure the normal indication of the water level gauge and the accurate and reliable action of the automatic water level regulating valve. Even if the self-regulation is put into operation, the water level should be checked frequently and strictly controlled within the specified range.
