Problems with PX adsorption separation
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The PX adsorption separation process developed by UOP can be implemented in two configurations: two towers with two rotary valves, or four towers with two rotary valves. Please, those with expertise in PX processes, provide detailed explanations regarding the advantages and disadvantages of these two configurations. I would like to express my thanks here first.
It’s basically the same; they are divided into these two types only due to processing volume issues.
Generally, the processing capacity of a rotary valve is 450,000 tons per year; the choice of different types is determined based on this processing capacity And many of them are prepared for future capacity expansion!
Many things are proprietary equipment of foreign companies; unlike ordinary equipment, where you can simply replace it with a larger one when you need to increase capacity, once the valve has been chosen, if you still want to increase capacity you have to ask those companies to supply the equipment. Therefore, it’s necessary to build in sufficient margin during the design phase.
Patented equipment is one aspect. Because there are many valve channels, it is difficult to ensure no leakage between them when the surface area becomes too large. All are limited by face sealing, so currently a single valve corresponds to 45 wt/a. Placing several towers and rotary valves and such is something that has to be done as a last resort. If one wants to use large-scale equipment now, options include Eluxyl from France and the domestic technology introduced in 2011. Both of these technologies use programmable valves for control, and in principle, there is no upper limit to the production capacity of a single unit. France has few technical valves, but there is bypass channel flow ； Domestic technology is better in this regard, but there are a few more valves.
With today’s French technology, backmixing no longer occurs in the bypass system
With today’s French technology, backmixing no longer occurs in the bypass system