Air separation plant.In the switching heat exchanger, due to the lack of air flow, it is easy to produce uneven distribution of air flow, that is, "bias flow". The bias flow will worsen the heat transfer and self cleaning conditions, especially in the multi unit plate fin heat exchanger. The bypass valve can increase the air flow into the switching heat exchanger and effectively prevent the generation of bias flow.Air separation plant.The cooling water is preferably softened. It is easy to use magnetic water softener for softening treatment, and the effect is acceptable. Sedimentation tank should be set up to remove suspended solids. If the cooling water is recycled, it is conducive to the softening of water quality, but it covers a large area and has a large capital investment.Water cooling tower is a kind of hybrid heat exchanger. The cooling water with higher temperature (about 35 ℃) from the air cooling tower flows downward from the top spray, and the sewage nitrogen with lower temperature (about 27 ℃) from the switching heat exchanger flows from bottom to top. The two are in direct contact, which is a complex heat transfer process with heat and mass transfer.
Air separation plant.The underground pipeline of dry oxygen can be laid above the freezing line, but the depth is not less than 0.8m, so as to avoid pipeline fracture caused by ground transportation load. Other regulations can be carried out according to relevant regulations; the oxygen pipeline shall be equipped with static electricity conducting grounding device;Prepare the foundation according to the manufacturer's drawings and local soil conditions. Clean the foundation hole and prepare about 10 pieces of pad iron (recommended as 100 mm × 60 mm × 15 mm, slope ratio of 1:12). Check the appearance of the wooden box, and then open the box to check the spare parts and accessories;Air separation plant.At the beginning of the start-up of the full low pressure oxygen generator, all the air entering the unit is expanded by the expander, and the total expansion volume of the expander (including the standby one) set in the unit is much smaller than the exhaust volume of the air compressor. In addition, the inlet air temperature of the expander is much higher than the design value at the beginning, and the actual air flow into the expander is less than the design expansion amount.
Air separation plant.When the scale is serious, it must be removed. The cleaning methods are usually mechanical or acid washing. The mechanical method is to brush off the scale with an iron brush; the pickling method is to use the dilute solution containing 10% hydrochloric acid to clean with a small water pump, dissolve and remove the scale with acid (because the scale is generally alkaline), and then neutralize it with alkali. It should be noted that the acid should not be too thick to avoid corrosion of metal.Air separation plant.The greater the pressure difference of molecular sieve switching, the greater the pressure on the sieve bed, which will be detrimental to the safety of molecular sieve bed. Therefore, we should pay close attention to the molecular sieve heating, cold blowing and other processes. It is disadvantageous to take too long and too short time to equalize and relieve pressure.Air separation plant.The output work of the expander reduces the pressure and temperature of the gas and the enthalpy. Gas reduces energy and increases heat absorption capacity, which is called refrigerating capacity of expander. Therefore, the refrigerating capacity of the expander, that is, the amount of external work it does in the expansion process, is equal to the reduced enthalpy of the gas in the expansion process.
