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In Naphtha cracker the molecular sieve dryers are regenerated with Methane. But in Isomerization plant(MSQU) the molecular sieve dryers are regenerated with the valuable product isomearte. Is it possible to regenerate with off gas or fuel? is any limitation as these streams contains sulphur...?
 
Answers
04/05/2015 A: Amardeep Puri, Axens India Private Limited, amar9403@gmail.com
The Isomerization dryers cannot be regenerated using the stream containing sulfur as the dryer molecular sieves have affinity towards sulfur species. This shall lead to ineffective regeneration and partial adsorption of sulfur on the molecular sieves. As organic sulfur is poison for isomerization catalyst, the adsorbed sulfur can slip to reaction section during normal operation and can deactivate the catalyst.
Moreover, the isomerate stream used for regeneration can always be routed to gasoline pool along with product isomerate.