How long after stopping the feed should a blind flange be installed?
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In a catalytic cracking unit, how long after the feed is cut off can blind plates be installed?
Our standard procedure is to stop feeding at 0:00 in the evening, and to discharge the material from 0:00 to 6:00； Oil removal from the fractionation stabilization system; distillation column operation at 6:00 (for 1 hour) ； Then reduce the steam injection for the reaction; reduce the steam supply to the bottom of the distillation tower, and open the condensate drain at the bottom of the tower to allow a small amount of steam to be released ； Install blind flanges in conjunction with maintenance work. Generally, the time between stopping the feed and starting to install blind flanges is 8 hours.
A blind flange should be installed as soon as all the oil and gas in the settler have been removed
This post was last edited by karamay on 2010-7-15 at 18:34. After stopping the feed, the reaction section undergoes cyclic burning, cooling, and catalyst removal; in the distillation section, the side line pump is used to evacuate the system before it is stopped, followed by steam supply, oil injection, and initial purging. All the oil is sent back into the tower and removed using an oil slurry pump. The reaction process should not have its steam supply stopped during purging, which should continue for one hour. Once the temperature of the reaction mixture drops below 200 degrees, blind flanges can be installed.
To install a blind plate, we first need to consider the conditions: 1. There is no oil left in the distillation tower； 2. There is no catalyst left in the settler; at this point, the steam supply can be increased, and then the steam supply can be stopped to install a blind flange. The various devices differ; some discharge the agent quickly, while others do so more slowly ； For a fractionation tower, all one needs to do is close the draw-off and return valves, empty the bottom of the tower as well as the re-refining tank and feed tank, and then purge it with steam. The time still cannot be unified.