Pressure drop issues in gasoline hydrogenation reactors
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Dear colleagues, I have a question regarding the pressure drop in the gasoline hydrogenation reactor. A few days ago, during the switching of the recycle hydrogen compressor, the amount of recycle hydrogen increased suddenly from 18,000 to 30,000–40,000, causing the flow rate to exceed the allowable limits. Subsequently, the pressure drop in the second stage of the hydrogenation reactor gradually increased, reaching 0.44 MPa, while the pressure drop in the first stage was 20–30 KPa. When the production volume was increased, the pressure drop in the second stage rose further, whereas the pressure drop in the first stage remained almost unchanged. This reactor is a two-stage reactor, with cold hydrogen used for cooling in between. What could be the cause of this issue? The plan for shutting down the equipment for maintenance has now been prepared; we would appreciate your advice, dear colleagues～
Is it possible that during the switching of the compressor, the pressure and flow rate increased abnormally, resulting in damage to the catalyst bed? Was it packed in a dense phase previously?
The issue of impurities has been taken into account, but logically, an increase in pressure drop should result in a sudden rise in the pressure drop of the first layer; instead, it is the second layer where there is a sudden increase； The catalyst has always been packed in a dense manner, so there is no issue with void spaces
Is it only the pressure drop that is abnormal? What is the temperature rise in the second bed layer? Is it possible for impurities from cold hydrogen lines to affect the catalyst?
The cold hydrogen line has been in operation continuously, with no significant changes in flow rate； There was also no significant change in the temperature rise of the second bed layer; mainly, the properties of the raw materials used in our plant are not very stable, which results in unstable temperature rises in the reactor. A comparison before and after shutting down the machine indicates that there should be no problems. Did the collapse at the bottom of the first bed layer cause the catalyst to be transferred to the second bed layer, resulting in an increased pressure drop in the second bed layer?
An increase in the amount of circulating hydrogen leads to an increase in the pressure drop across the reactor bed; this is a contradictory phenomenon. It is necessary to check whether there are any changes in the quality of the gasoline produced by the unit. If no changes occur, then it is likely a problem with the instruments; if there are issues, then process-related problems should be considered.
One thing isn’t clear: during the shutdown, the flow rate of circulating hydrogen reached 30,000–40,000, and after the shutdown it dropped back to the normal level of around 18,000. After that, an increase in pressure drop across the second bed layer occurred, which is quite puzzling. The instruments have been checked and show normal readings. I’m guessing that the sudden change in pressure might have caused some issues with the equipment. I wonder if other users have encountered similar problems before
I now suspect there might be a problem with the distributor on your second floor.
I thought the same thing – is it possible that a sudden increase in pressure drop causes leakage at the bottom of the first bed, allowing catalyst to flow into the second bed and block the distributor, which in turn leads to an even higher pressure drop? Judging from the latest readings, this seems quite likely