Jim Grant Forum Moderator 119 Posts
Re: Can cooling jackets be used with PFRs?3 March 2009 at 1:29pm
The use of a cooling jacket on a plug flow reactor is highly dependent upon the scale, degree of exotherm and temperature difference between coolant and reaction media. In many applications the reactor is essentially a shell & tube heat exchanger in which a cooling media flows on the shell side and the reaction takes place in tubes packed with catalyst. When there are large exotherms and the potential for runaway reactions this type of design is preferred. The calculations required to determine whether the jacket is sufficient are fairly simple: Do an energy balance to determine the heat removed and then determine what temperature cooling medium would be required to satisfy the heat removal with the available jacket area and an estimate of the heat transfer coefficient. If you find that the required cooling medium temperature is not realistic or practical then you will have to revise the reactor design to contain more heat transfer surface than a jacket.
I am working on a plant design project for my CHE433 course. The plant produces 20,000 tons of hydrogen peroxide per year. My teacher asked me about how I was planning to cool the main reactor where H2O2 is produced and where exothermic reaction occurs and 188906.4 KJ/kmol*hr are released. I told him that a cooling jacket would do the job. He said, "No, in fact cooling jackets are not used with plug flow reactors (PFR) and you should have known it. Looking at your Web site, I found one person asking about a problem he encountered on the cooling jacket around a PFR -using water flow in- and some answers came in from PhD people. So I see that cooling jackets can be used with PFR. Am I wrong? What would you suggest as a cooling method for my exothermic conditions?
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