Treatment of excessive tower pressure in the catalytic reforming distillation column in petrochemical processing
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I graduated from university in 2015 and am currently working at a catalytic reforming unit in a petrochemical company; I’m feeling quite lost at the moment. For example, yesterday the pressure in the stabilizer tower (fractionation tower) was too high; the technician instructed that the reflux level be reduced. I just couldn’t understand why – if the reflux level is lowered, shouldn’t the pressure at the top of the tower increase instead? Wouldn’t that mean more material would flow upward? But the fact is that as the temperature at the top of the tower rises, the amount of dry gas in the reflux tank drops immediately. Help!!! The problem might be quite silly; please don’t criticize me
The pressure in the distillation tower is related to the pressure in the reflux tank; when the flow rate of dry gas decreases, the pressure surely drops as well. The pressure is influenced by the opening degree of the valve used to control the flow of dry gas outward, or by the backpressure. Reflux serves to control the temperature of the distillation tower – a lower reflux flow rate results in a higher temperature, which leads to more components being separated out. This in turn causes the liquid level in the reflux tank to rise. Is part of the liquid from your reflux tank sent outside? Also, check whether adjusting the reflux flow rate helps to adjust the pressure To adjust the quality at the bottom or top of the reflux control tower, the pressure is controlled by adjusting the opening degree of the external dry gas control valve; please check your curves to see if the quality is satisfactory!
Our fractional distillation reflux tank features automatic control of the tank pressure; whenever there is a change in pressure, the control valve adjusts automatically. If you use a manual system to keep the pressure constant, then the valve opening should be increased!
We use automatic control valves to regulate pressure; currently, the pressure is directed to the outlet of the catalytic cracking stabilizer compressor. The pressure in that circuit is relatively high, and even when the control valve is set to 100%, the pressure continues to rise. We don’t want to use the flare system, as that would result in waste. After we introduced backflow that day, the temperature at the top of the tower increased, but the dry gas level in the backflow tank decreased instead; I can’t understand this
Check if there are any other effects; this doesn’t make sense. Do your distillation columns have reflux tanks equipped with dehydration units? Is the pressure fluctuating or rising continuously? Consider whether there might be a water issue! If there is a bounded position, aren’t there also some fluctuations!
Reflux involves the light components; since the temperature at the bottom of the tower is required to remain constant, reflux occurs more rapidly than the oil at the bottom of the tower rising upward. Reducing reflux means that less oil from the tower itself rises upward