Butane removal tower feed control
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The feed to the butane removal tower is divided into two streams: the upper stream consists of cold light fractions that, after heat exchange with diesel, enter the tower at its 12th stage, while the lower stream comprises hot light fractions that are fed directly. During the startup of the plant, since the amount of cold light fraction feed is relatively small at the beginning, the temperature of the feed after heat exchange is higher than that of the feed in the lower stream. As a result, all parameters in the butane removal tower fluctuate, especially the liquid level at the bottom of the tower; these fluctuations follow a pattern similar to that of a spring. Only after the temperatures on the upper and lower streams returned to normal did the butane removal tower gradually stabilize. I would like to ask everyone what causes these fluctuations; it would be great if there could be a thorough explanation. Also, how can we ensure that such issues are resolved quickly during operation? Is it sufficient to use a bypass line for heat exchange?
I asked an expert before, and they mentioned something called \"temperature inversion\"; I had never heard of this concept before. It would be great if you could explain it as well. Thank you very much
In the upper feed line, the low flow rate at the beginning of operation caused the temperature of the diesel after heat exchange to become too high. Based on your description, I think it might be due to an excessively high feed temperature, resulting in a phenomenon similar to tower flooding. Appropriate bypassing can be used in the diesel heat exchanger to adjust and reduce the feed temperature of cold light fractions. At the same time, appropriately reduce the temperature at the bottom of the butane removal tower. Increase the tower pressure a bit, and try increasing the reflux volume as well