Quality control method for side-stream products from distillation columns
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Qualified products are obtained from the side stream of the distillation tower; when the content of light components in the product is high, what methods can be used to reduce the amount of light components in the side stream product in order to ensure product quality (without considering changing the extraction point)? My idea is to slightly increase the back pressure: by 1–2°C at the cooled temperature ； 2: Slightly increase the kettle temperature and reflux rate ； 3: The original tower did not have a pressure control system. I think that by adding a control valve for discharging material after cooling, a pressure control system can be established to increase the tower pressure appropriately. I would appreciate it if fellow sailors could advise me to see if my understanding is correct.
You need to first understand the reason why the product from the production line contains a high proportion of light components before taking any action. It might be that changes in the feed composition have led to an increased amount of light components in the output. Identify the cause clearly before taking targeted measures
With just one step, you can gradually reduce the amount of product taken from the side stream, until you find a point at which both the top of the tower and the side stream meet the required standards. However, it’s not possible to raise the level of the side stream too high; this is how we handle it, mainly by addressing the issue of material balance.
The textbook on petroleum refining provides a solution: the straightforward method involves increasing the heat input at the bottom of the side stream tower, which is both simple and direct； Regarding what you mentioned just now, in short, the conclusion is that raising the temperature at the sidetrack production point is feasible; whether this is done by increasing pressure or by lowering the production point, either method will work. It’s most important to choose the best option among them. But it is necessary to ensure that the direction of change is correct; it seems that what you have listed does not capture the essence of things. The goal is to raise the temperature at the extraction point, and the methods follow from that.