Showing posts with label refining. Show all posts
Showing posts with label refining. Show all posts

NH3 Slip Measurement in the Fluidized-Bed Catalytic Cracking Process


Fluidized-Bed Catalytic Cracking (FCC) is the most important and widely used refinery process for converting low value heavy oils into more valuable gasoline and lighter products.

The typical FCC process will convert 75% or more of the heavy oils to gasoline and lighter products. Originally, chemical cracking was accomplished by heating the oil to super high temperatures but the catalytic process has almost completely replaced thermal cracking.

The cracking process produces carbon (coke) which remains on the catalyst particle and rapidly lowers its activity. To maintain the catalyst activity at a usable level, it is necessary to regenerate the catalyst by burning off the coke with air. As a result, the catalyst is continuously moved from reactor to regenerator and back to reactor.

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Monitoring Catalyst Presulfiding

Catalyst ‘presulfiding’ is a practice which reduces the extent of early catalyst deactivation on by preventing coking (carbon deposits). The procedure involves passing a gas stream containing H2S over the catalyst or into the reaction feedstock.

In order to generate the H2S which will interact with the catalyst, a sulfur carrying agent (e.g. dimethyl sulfide) is injected into the stream. Under high temperature and catalytic reaction, the agent decomposes and releases its sulfur component, forming H2S. The H2S reacts with the catalyst’s metallic surface to substitute sulfur atoms for oxygen atoms.

Read the document below to learn more about monitoring this process with the Applied Analytics OMA-300 H2S Analyzer