Abstract:
CO2 Removal from Syngas is an important step before ammonia production to
enhance the life of iron catalysts in ammonia reactor. At FFBL, hot potassium
carbonate (Benfield) solution is used to dissolve CO2 from syngas. This solution is
regenerated through steam and the overhead of carbonate regenerator is separated
into CO2 rich vapor stream and Benfield process condensate PC. About 84000 kg/h
of condensate is produced, 1/4th of which is dumped into the Indus River.
According to environmental and economic aspects, it is beneficial to reuse this water
as boiler feed instead of discharging it as an industrial effluent. Although free of
major impurities like total dissolved solids TDS and total suspended solids TSS,
Benfield PC contains two dissolved gases CO2 and NH3 which render it unfit for
boilers.
Several biological, chemical, and physical processes were reviewed including
nitrification-denitrification, ion-exchange resins, membrane separation, steam
stripping, and flash distillation. Steam stripping was found to be a commercial and
proven technology for water degassing even at very low concentrations.
In this project, a cost-effective stripping system with economized feed preheating
has been optimally designed to bring Benfield PC within boiler feed specifications
