Diesel extraction issue in the fractionation tower
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I went to work today. The shift supervisor in charge of distillation suddenly called for the team leader to come inside. No diesel is coming out of the diesel line; the outlet valve is closed. Could all the teachers please help analyze why diesel cannot be obtained? Another phenomenon that occurred was a drop in temperature.
“What does ‘no diesel can be drawn out from above, and the outlet valve is closed below’ mean? Have you turned on two outlets? Besides that… You have a bit too little data, making it difficult to judge.
Have any other parameters changed? What about the mass of the raw gas? And what about the volume of the raw gas? Sharing a DCS photo
It is suspected that it is a problem with Line 1; both the flow rate and temperature on Line 1 need to be checked. Determine the cause of the temperature drop – whether it is due to restrictions at the tee connection or internal leakage in the heat exchanger
If there is a sudden change, first check whether the control valve is faulty or if there is a problem with another part of the process
Check the liquid level instrument of the stripping tower; apart from the temperature drop in the middle and return streams, are there any other parameter changes? Is there no distillate output at all, or does it decrease gradually? It’s getting smaller gradually; perhaps the distillation outlet is blocked, which causes a sudden drop in flow rate. It could also be that the instruments are inaccurate, or there are problems with the trays or the distillation valves.
Let’s analyze gasoline and diesel! Could it be that the diesel wasn’t separated properly and ended up going up there? If instrument and equipment issues are ruled out, the most likely cause is salt buildup in the distillation tower!
What needs to be done after salt formation?
It’s reasonable to suspect that the vaporization line of the light fuel tower might not be functioning properly. Sometimes, for no apparent reason, diesel won’t distill out, and this situation can last for a long time; but suddenly it will start flowing again. We cut off a bit of the 90-degree elbow in the pipes inside the diesel distillation column, changing the horizontal section of the distillation line to an inclined one.
It’s tower cleaning! Reaction drop volume shunt for deoxygenated water washing tower
How large is the upward volume? I just went through it in November. The solution is to increase the upward flow rate, reduce the amount of raw gas sent outside, and use cold reflux for tower cleaning.