DEAR Air separation 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);When the switching heat exchanger is cooled close to the normal condition, that is, the self clearing condition has been basically established, and the temperature difference at the cold end has been basically stable, the bypass valve will gradually lose its function. If it continues to open, it will result in excess cooling capacity of switching heat exchanger, expansion of temperature difference at hot end, increase of incomplete heat exchange loss, and insufficient utilization of cooling capacity to accumulate liquid.DEAR Air separation unit.In case of sudden power failure of the air separation unit in the molecular sieve purification process, the following operations should be carried out: first, open the vent valve (anti surge valve) of the air compressor to prevent the air compressor from surging, or the air reverse flow causes the air compressor to reverse; the switch valve of the molecular sieve adsorber should be closed by interlocking.
DEAR Air separation unit.Generally, it takes more than 36 hours for a large air separation unit from start-up cooling, liquid accumulation and purification to produce qualified products, among which cooling time is about 10 hours, liquid accumulation time is about 20 hours and purification time is 6 hours. For the air separation unit of molecular sieve purification process, there is no problem of water precipitation, freezing and carbon dioxide precipitation. However, during the whole start-up process, the cooling capacity required by the unit is certain.The temperature of the liquid blown out from the automatic valve box of the accumulator (or switching heat exchanger) or the backflow sewage nitrogen at the cold end is about - 180 ℃, which is the sign that the air at the cold end of the accumulator (or switching heat exchanger) is liquefied. The harm of air liquefaction at the cold end is great, mainly as follows: part of the liquefied air is deposited in the automatic valve box (or at the bottom of the cold accumulator), and part of it is brought into the tower with the air, so that the moisture content of the air entering the tower increases, and the liquid air purity (oxygen content) decreases.
The quantity and temperature of expansion air are determined by the balance of cooling capacity of the whole unit, and adjusted by the distribution ratio of the two air volumes after the first heat exchanger. If we insist on increasing the air temperature in front of the expander, we need to increase the air flow through the second heat exchanger, which will inevitably increase the temperature after expansion and the temperature before throttling.After several stages of air compressor cooler leakage, in operation will not occur water accident (because the air pressure is higher than the cooling water pressure). When the air compressor stops, the cooling water may still enter the air passage. If not drained, once the air compressor is restarted, water will flow into the air separation unit. In addition to the above two large-scale water inflow conditions, if the heating gas is not dry, the water will also be brought into the regenerator (or switching heat exchanger) during thawing and heating.
DEAR Air separation unit.Improper use of bactericides and algicides. For the poor cooling water, if the use of bactericidal algicide, it will produce a lot of bubbles in the cooling water, causing air to carry water. At this time, attention should be paid to adding the dosage of sterilization and algae killing, or adding defoamer at the same time;DEAR Air separation unit.When the air separation unit of molecular sieve adsorption purification process is restarted after a short-term shutdown, attention should be paid to: the air compressor should be boosted slowly to prevent the impact on the air cooling tower due to the sudden rise of pressure. The water level of the air cooling tower should be paid attention to to prevent the molecular sieve adsorber from entering water due to the high water level;DEAR Air separation unit.It has been widely used in large and medium air separation plants. The plate unit is generally arranged in a vertical star shape. Because the height of plate unit is limited by safety, the heat exchange area that can be arranged in the range of tower diameter is limited, and the double-layer or multi-layer (four layer) star arrangement is used in large air separation units.
