After a long-term operation of the air separation plant, the components in the low-temperature equipment and pipelines in the distillation system will be blocked due to the internal precipitation of ice or mechanical powder, which will increase the resistance of the fractionator. After 2 years of normal operation of the air separation plant, the fractionator system should be heated and defrosted to remove these sediments. In case of water inflow or other failures of molecular sieve adsorber and main heat exchanger, shutdown and heating shall also be conducted. Generally, the following methods will be used for heating and thawing.
For heating and thawing operation during normal shutdown, the air separation unit shall conduct large liquid discharge after normal shutdown. After liquid discharge, the equipment shall stand for 24 hours, start the air compressor, precooling system and purification system, introduce dry air into the lower tower through the main heat exchanger, and open all liquid discharge valves of the lower tower, so that impurities accumulated in the main heat exchanger and lower tower are reheated and discharged out of the cold box. Open the liquid air throttle inlet upper tower valve and liquid nitrogen throttle inlet upper tower valve, guide the heating gas into the upper tower, and open the upper tower purge valve according to the flow path for heating. When the inlet and outlet temperatures of the heated gas are basically the same, the heating is completed.
The long-term stable operation of the equipment has a lot to do with the use of customers. DEAR provides technical training to customers on the principle of air separation equipment to ensure correct and reasonable operation.
