How to prevent freezing during the shutdown of hydrogenation units
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The circulating water pipelines and steam pipelines are dried with nitrogen to remove water.
During shutdown for maintenance, the inlet and outlet of the circulating water in the pump body are closed to drain any remaining water. After the diesel has been replaced in the reaction system, it is purged with nitrogen. The distillation system was purged with diesel and cleaned via steam blowing. If the steam line is not in use, close the boundary valve to drain any remaining water, and open a reverse condensate line in front of the valve to vent steam. Drain the instrument air by opening a manual valve at the bottom of the air tank or the filter.
Additionally, depending on the duration of the shutdown, the liquid levels in the separation tower and the finished product distillation tower are adjusted, and the materials that tend to solidify at the bottom of the towers are removed promptly
All the required bypass heaters are turned on to replace heavy oil with light oil.
Use flushing oil and purge hydrogen to clean the equipment thoroughly; vent steam directly at the end, and drain water from the lowest points in the pipelines using air for purging. Check that there is no water accumulation in the pipelines in the low-lying areas of the device