Offgas treating process

The Shell Claus Offgas Treating (SCOT) Process... 

This finding is based on EDS I CATOX tests by Parsons/Honeywell and also on the differences between the design tested and the offgas effluent treatment system proposed for the SILVER II process. Since the AEA CATOX unit is modeled after the Parsons/ Honeywell design, it can be expected to produce similar amounts of dioxin and furan. In addition, the gas treated by the AEA CATOX unit has a different source and therefore a different composition. No CATOX units have been tested on gases from this source. 

Reactor product gases were effectively treated in the two-stage scrubber system and product gas burner. However, Eco Logic concluded that process modifications might be necessary to control hydrogen sulfide and phosphine in the offgas from the reactor. Also, the liner in the product gas burner showed evidence of corrosion. 

The spent activated carbon from plant HVAC filters and from respirators is first heat-treated in a heated, helical screw conveyor to drive off agent and is then reduced to less than 0.5 mm in a wet spent carbon grinder. Offgas from the processing of the carbon will be treated by the gas treatment system of either the projectile rotary hydrolyzer (PRH) or the ERH. The micronized carbon is mixed with water in the hydropulper (Step 9) and separately processed through the SCWO reactors of the energetics hydrolysis system. 

Scrubber water from the energetics offga.s treatment (OTE) system. Scrubber water from the OTE is to be treated through subsequent processing. Neither the waste nor the subsequent processing has yet been characterized. 

As in the Concat process, the wet catalysis principle is used also by a process developed jointly by Topsoe and Snea. This process differs from the Concat process by an additional acid concentration stage so that sulfuric acid concentrations up to 95 % can be reached. The SO2 content of the offgas from this process, too, remains below 200 vol. ppm. Like tiie Concat process, the Topsoe process can also be used for treating tailgases from Claus units. 

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