Should the control valve on the feed line of the atmospheric and vacuum distillation unit be air-operated open or air-operated closed?
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I would like to ask everyone: should the control valves on the main feed pipe for atmospheric and vacuum distillation, as well as on the branch pipes that divide off from it, be of the air-operated open type or air-operated closed type? From the feed perspective, crude oil is flammable and explosive; therefore, it should be shut off in case of a fault, that is, activated by gas ； However, since crude oil serves as the main cooling source for atmospheric and vacuum distillation units, from this perspective, it should operate in fail-open mode, that is, shut off by gas. I’ve seen the blueprints for several sets of devices, and they’re all different; I hope an expert can provide an explanation.
If it’s not going into the heating furnace and there is a flash tower, of course use an emergency shutdown to disconnect it from the outside of the plant – it’s safer that way.
The technician question bank provides clear answers; the air shut-off valve is used to prevent problems with the equipment due to a loss of power.
For FO gas shut-off valves, if they are operated using gas, the flow of gas to the valve is stopped. Once the feed is interrupted, the oil inside the furnace tubes ceases to flow, which causes the temperature to rise sharply, increasing the risk of accidents. This is the first reason why gas shut-off valves should be used for the feed valves in furnaces. Feel free to add your comments below. (I’m a beginner who has only been working for a year; the above are my personal opinions. Please don’t criticize me – I’m here to learn from you all.*)
Isn’t the raw material cut-off valve for that purpose?