The functions and purposes of the gasoline hydrodesorption cycle and the reaction cycle
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The operating procedures state: \"In the event of a raw material supply disruption, first reduce the flow rate and switch to the large-loop mode (close the valves controlling the inflow and outflow of gasoline at the unit, and direct the product stream back to the raw oil tank). If it is not possible to resume normal operation immediately, switch to the distillation loop and reaction loop. If feeding cannot be resumed even after 1 hour, proceed with a normal shutdown procedure.\" ” I have a few questions I’d like to ask the teachers: 1. What is the purpose of not being able to resume feeding at the moment, and what role do the fractionation cycle and the reaction cycle play? Are this distillation cycle and reaction cycle the distillate heating cycle at startup and the pre-sulfidization cycle of the reaction system? What’s the difference if not? What state should the hydrogenation and desulfurization reactors be in? 2. Why change the fractionation cycle and reaction cycle? Can’t we just use the large-scale cycle of the plant to keep it running for 1 hour; if feeding cannot be restored, then shut down the system? Why?
1. The fractional heating cycle and reaction sulfidation cycle used at the start of operation are designed to ensure circulation; the main purpose of this is to protect the catalyst. Imagine that if feeding is interrupted, the bed temperature will rise. As a result, the reaction rate will increase, making it difficult to control the levels of light and heavy fractions. It may also lead to coking in the catalyst bed. Additionally, these cycles help to shorten the time required to restore the operation of the plant. The principles for reaction operation are to first increase the flow rate before raising the temperature, and to first reduce the temperature before decreasing the flow rate. 2. Increasing the circulation rate does not necessarily guarantee the minimum feeding volume required by the plant. Moreover, it is difficult to maintain the quality of reaction products when feeding is interrupted. If feed enters the distillation system, it may result in oil products of substandard quality. It should be noted that the oil temperature entering the raw oil tank via the reaction cycle is relatively high, so proper heat exchange adjustments are necessary
Running in a loop is done to shorten the feeding time and protect the catalyst. If the supply of material cannot be restored for an extended period, it is necessary to proceed with shutdown procedures in order to reduce temperature and flow rates, thereby preventing sulfur loss from the catalyst.
It is to ensure that the system continues to operate properly, preventing sudden interruptions in feed from causing the bed temperature to rise too high and leading to coking and breakdown of the catalyst.
"Since attempts to reduce the reactions increase, it becomes difficult to control the high and low scores. “Could you please explain what that means? I want to learn.”*