Hydrocracking startup
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Why is a vacuum test conducted after the catalyst is loaded during the startup of hydrocracking, and how is it determined whether the vacuum test is successful?
The vacuum test of the reaction system serves two purposes: 1) to conduct a gas-tightness test and check for any leaks in the reaction system, with a value of ≤10 mmHg considered acceptable; 2) the vacuum test is intended to remove oxygen from the system quickly, as oxygen is a very dangerous gas in a reaction system. At high temperatures, it can combine with hydrogen to form explosive gases, and it can also react with iron present in the vessel walls or pipes to produce iron oxide. Such iron oxide particles can damage the compressor impellers or clog the reactor bed.