When the unit is in normal operation, the cooling capacity is mainly to balance the cooling capacity loss of the unit and the cooling capacity needed to produce a small amount of liquid products. Generally speaking, according to the design conditions, an expander can meet the requirements. When an expander can not maintain normal liquid level, there must be abnormal cooling loss such as internal leakage. At this time, it can't solve the fundamental problem to increase the refrigeration capacity only by increasing the expander. But we should first find out the reason for the increase of cooling loss.When the absolute pressure is increased from 0.55mpa to 0.6MPa, the liquefaction temperature can be increased by about 1 ℃, and the cooling capacity difference needed to condense 1kg air is about 2kJ. At this time, the bypass valve from the air to the waste nitrogen pipeline should be closed to increase the downtower pressure. Of course, there is a limit to the increase of pressure.DEAR Biogas purification unit.Adjust the excess hydrogen in hydrodeaeration to meet the process requirements. Adjust the working conditions of the deaerator, and the furnace temperature is generally stable between 350 ℃ and 450 ℃ (if the furnace temperature does not meet the requirements, the palladium metal on the surface of the palladium catalyst may be lost due to long-term use, and the efficiency will be reduced, so the palladium catalyst can be replaced);
In the actual expansion process, due to the loss of mechanical friction and eddy current, the external work is reduced. It also transfers the heat energy to the gas, so that the actual enthalpy drop is reduced, the unit cooling capacity is reduced, and the temperature drop is also reduced. The expander efficiency η P is the degree that the actual expansion process is close to the ideal expansion process, that is, the ratio of unit actual refrigerating capacity △ h and unit theoretical refrigerating capacity △ HT.The causes of leakage are as follows: the pipes are worn away from each other due to vibration. For the long tube condensing evaporator, there are tens of thousands of copper tubes with a diameter of 10 mm and a length of 8 m, and the tube spacing is very small. In the process of operation, due to the impact and vibration of the air flow, it is easy to bend and deform in the middle of the pipe and rub against each other, which may cause wear loss for a long time.In order to cool the equipment and accumulate liquid as soon as possible in the start-up stage, the refrigeration capacity of the air separation unit which produces gaseous products is much larger than that of the normal production. For example, for small medium pressure air separation units, the refrigerating capacity can be increased by increasing the air pressure; for low pressure air separation units, the refrigerating capacity can be increased by increasing the expansion capacity.
DEAR Biogas purification unit.The oxygen pipeline must be cleaned and degreased before installation; the oxygen pipeline in the plant should be laid along the wall or pillar. The connection points of all pipelines and their auxiliary equipment shall be placed at conspicuous and convenient places for inspection; in the case of open laying, the oxygen pipeline and other pipelines are allowed to be laid at the same time, but the oxygen pipeline shall be laid on a separate support or hanger, and shall be laid on top of other pipelines. The distance between the oxygen pipe and other pipes is greater than 250mm;For the detection pipeline with wet gas as the measured medium, a condensing device should be set at the lowest point of the pipeline to prevent the liquid from accumulating in the pipeline; for the detection pipeline with liquid as the measured medium, when the pipeline and instrument are higher than the measuring point, a vent valve should be installed at the highest point of the pipeline to prevent the gas from accumulating in the pipeline;
DEAR Biogas purification unit.In chemical industry, in the process of chemical fertilizer production from synthetic ammonia, in addition to nitrogen as the main feed gas, oxygen is used in high temperature cracking of heavy oil, gasification of pulverized coal and other processes to strengthen the process and increase the output of chemical fertilizer. Generally, a 100000 t / a ammonia plant needs to be equipped with a 10000 m3 / h oxygen generator. In addition, a large amount of oxygen is consumed in the production of methanol, ethylene and propylene from natural gas reforming, oxidation, desulfurization and recovery. When the oxygen consumption per ton of product is in the range of 300-1000m3 / T, 10000-30000m3 / h oxygen generator should be equipped.DEAR Biogas purification unit.Coil type is generally used for auxiliary condensing evaporator. Liquid oxygen boils in the tube and gas nitrogen condenses between the tubes. There is no fixed liquid level in the coil. Because of the small heat transfer coefficient, it has been gradually eliminated. The main condensing evaporator (liquid oxygen self circulation) of Hitachi 6000m3 / h oxygen generator in Japan also adopts coil type.
