DEAR Biogas purification unit.Water is sprayed from the top of the tower to contact and mix with the air to cool the air. A plurality of cross flow sieve plates or fillers are arranged in the air cooling tower to increase the gas-liquid contact area. In order to separate the water, a water capture layer is set on the top of the tower. When the air flow rate in the air cooling tower is too fast, the water carrying or spraying amount is too much, and the water level automatic regulation fails, the water inflow accident of Molecular Sieve Purifier will occur.After cold blowing, the temperature decreases and a flat head peak appears. The longer the curve distance of the flat head peak is, the more water enters into the molecular sieve. In order to prevent the water inflow accident of Molecular Sieve Purifier, attention should be paid to the operation: the air cooling tower should be operated according to the operating procedures, first the gas is injected, and then the water is injected after the pressure rises and stabilizes; the gas volume should not be increased or reduced suddenly;
DEAR Biogas purification unit.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.DEAR Biogas purification unit.Due to these reasons, the temperature difference at the hot end increases, which will stabilize to a certain extent and will not continue to increase. The increase of the pressure difference before and after the heat exchanger is not necessarily due to the freezing of the heat exchanger. Because the molecular sieve in the purifier is broken, or the service cycle is too long, the powder filter at the outlet pipe is blocked, or the valve of the pipeline is too small, the pressure difference before and after the heat exchanger will increase.
For the air separation unit with liquid air subcooler, part of the liquid in the lower tower and main cooler should be drained before starting to prevent the liquid air subcooler from blocking; when the temperature of the cold end reaches - 150 ℃, the circulating flow should be reduced as far as possible to prevent the circulation channel from being blocked by carbon dioxide;Incomplete heat exchange loss Q2 (or Q2). The cooling capacity of low temperature gas is recovered by each heat exchanger in the device. Ideally, the low temperature backflow gas leaving the unit should be reheated to the same temperature as the positive flow gas entering the unit. That is to say, only when the temperature difference at the hot end reaches zero can all the cold energy be recovered. However, heat can only be transferred from high-temperature objects to low-temperature objects. In order to transfer heat from high temperature material to low temperature material in heat exchanger, there must be temperature difference. The temperature difference △ t at the hot end reflects that the temperature of the low temperature gas in the unit is lower than that of the air entering the unit, that is, the cooling capacity cannot be fully recovered, and the cooling capacity loss is called "incomplete heat exchange loss". It is proportional to the temperature difference.
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.In order to have a preliminary judgment on the leakage position and leakage before shutdown for maintenance, and to shorten the shutdown time, many units have explored some effective methods in practice.DEAR Biogas purification unit.Carbon dioxide precipitation stage. In this stage, only the switching heat exchanger is cryogenic to freeze the carbon dioxide in the heat exchanger, which is carried out by the low-pressure backflow gas until the cold end temperature reaches - 170 ℃; in the fourth stage, the purified low-temperature gas is used to further cool other equipment until liquid accumulates in the tower, and then the distillation condition is further adjusted.
