Shut down of the catalytic compressor, adjustment of fractionation
Thread Content
Catalytic unit: What should the fractionation crew pay attention to and what adjustments should be made in the event of a shutdown of the air compressor?
Pay attention to changes in system pressure (controlled by the flare at the inlet of the pneumatic compressor on the reaction unit), and regulate the top temperature carefully to prevent overheating; cold reflux can be activated if necessary.
When the compressor stops operating, it primarily affects the pressure in the reverse regeneration system. In such cases, the operation staff responsible for the reaction process should control the system pressure by using the flare at the compressor inlet and the top butterfly valves. As long as the pressure remains stable, no adjustments are necessary on the distillation tower； If the pressure changes significantly, the withdrawal temperatures of the side streams and the top temperature of the tower should be adjusted accordingly to ensure that the quality of the side stream products remains satisfactory. When the crude gas oil stops flowing into the absorption tower, it can be sent along the unqualified stream and discharged from the plant directly, or it can be sent out through the plant’s output line after liquefied gas has been separated in the stabilizer tower.
When the compressor stops, the reaction unit must reduce its processing volume; otherwise, large amounts of rich gas will need to be vented through flares or the gas system, affecting the liquid yield of the catalytic cracking unit. To ensure product quality, the distillation unit requires corresponding adjustments, such as reducing the temperatures at the top and middle of the tower.
This post was last edited by liujia1987 on 2012-7-16 at 14:31. During normal operation, if the pressure at the top of the distillation tower is 0.095 MPa and the pressure drop from the top of the distillation tower to the inlet of the compressor is 0.03 MPa, a pressure gauge is installed before the compressor inlet. When the pressure is high, the control valve assembly connecting the compressor inlet pipeline directly to the gas pipeline network is opened to release pressure; when the pressure is low, the control valve between the compressor outlet and the top of the distillation tower is opened to supply pressure to the top of the distillation tower. I would like to ask at what pressure at the inlet of the compressor does it release pressure, and at what pressure does it replenish pressure? The compressor is of reciprocating piston type, with a secondary outlet temperature of 90 degrees. What temperature should be set as the high-temperature alarm for the outlet temperature?
It’s the catalytic cracking compressor, right? If it’s a reciprocating compressor, it’s a waste to use a flare at the inlet when the inlet pressure is high; it’s better to start another compressor – usually there is a spare one available. When the pressure is low, it is best to close the compressor inlet valve or partially unload the compressor (if it is equipped with a unloader); filling the outlet is also an option. The amount of filler required must be adjusted according to the pressure in the reaction settler
For the distillation unit, it is sufficient to ensure that the top temperature of the tower does not exceed the values specified in the process specifications, to maintain the level of the seal oil, to get ready to activate the large discharge system in order to control the bottom liquid level. The crude gas oil should stop being fed into the absorption tower and instead be sent directly out of the plant; alternatively, the stabilizer tower can be improved to ensure product quality, the tower load must be adjusted, and waiting is required until the compressor starts operating