DEAR Air separation equipment.1 g potassium dichromate or 2 g sodium nitrite can be added to each liter of water (not suitable for nonferrous metal degreasing); due to the toxicity or explosion of degreasing agent, attention must be paid to prevent poisoning and formation of explosive mixture. In alkaline cleaning, the pipeline with more oil stains is heated to 60-90 ℃ with 10% sodium hydroxide solution, then neutralized with 15% nitric acid and washed with clean water.DEAR Air separation equipment.The causes of automatic valve failure are: the valve is frozen by water and carbon dioxide, or stuck by other debris. If there is a small amount of impurities on the sealing surface, the valve will not be closed tightly. The fixing bolts of automatic valve seat are not tightened evenly, and air leaks from the gap of gasket, sometimes the gasket will be damaged, and the more leakage, the greater.The air tightness test of fractionator has been done before leaving factory, but the equipment may be damaged due to vibration during transportation. Therefore, air tightness should be checked again before installation. In addition, if severe frosting is found on the shell of the air separation tower after operation, or after overhaul, air tightness inspection is also required.
The moisture and carbon dioxide in the gas after circulation reheating are in unsaturated state, which is also conducive to preventing moisture and carbon dioxide from separating out in the expander. In a word, it is more advantageous to use circulation in advance, and it must be used before the cold end temperature of the switching heat exchanger reaches - 150 ℃.DEAR Air separation equipment.On the one hand, the corrugated fin in the middle of the partition plate supports the partition plate and increases the strength; on the other hand, it expands the heat transfer area, greatly increasing the heat transfer area per unit volume, so that the whole heat exchanger can be made compact. The fluid flows through channels in the fins. In order to realize the heat exchange between cold and hot fluids in the heat exchanger, the channels of cold and hot fluids should be arranged at intervals.DEAR Air separation equipment.Of course, the main cooling liquid oxygen surface is the main sign of whether the cooling capacity is balanced, not the only sign. Because the opening of the liquid air throttle valve is too large or too small, it will change the liquid level of the lower tower, and then affect the change of the liquid oxygen surface of the main cooler. However, this is not caused by the imbalance of cooling capacity, but by the improper distribution of liquid volume between the upper and lower towers, and the fluctuation of liquid level is also temporary.
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;DEAR Air separation equipment.Due to the uneven thickness of the liquid layer on the tray, too much gas passing through the thin part, high flow rate and short contact time with the liquid, the oxygen in the steam can not be fully condensed, and correspondingly less condensation heat is released, and the nitrogen molecules in the liquid can not be fully evaporated, which affects the separation of oxygen and nitrogen.
Due to the large heat capacity of the accumulator, when the temperature of the cold end reaches - 60 ℃, the temperature of the intermediate extraction is still above 0 ℃ after the water freezing stage. Therefore, for the process of intermediate extraction, in addition to the problem that the air at the cold end of the accumulator has passed through the freezing stage of moisture and carbon dioxide, there is also the problem that the intermediate extraction air has passed through the freezing stage of moisture.Because the backflow gas is less than the positive flow gas, the cold energy can be released as much as possible, and the temperature of the backflow gas out of the accumulator will increase, resulting in the reduction of the temperature difference between the cold end and the hot end of the accumulator. Large temperature difference at hot end, insufficient reheating and large loss of cooling capacity. Too large temperature difference at the cold end will affect the self removal of carbon dioxide, increase the resistance too fast, and shorten the operation cycle of the whole air separation unit.
