A PID ratio control for removal of HCl/SOXHCl/SOX in flue gas from refuse municipal incinerators

This paper presents a PID-based ratio control scheme for flue gas cleaning systems (FGCSs) to remove acid emissions (SOXSOX and HCl) from municipal refuse incinerators. The FGCS uses a semi-dry scrubber that injects diluted hydrated lime (Ca(OH)2)(Ca(OH)2) droplets to scrub high temperature, polluted flue gas from incinerators. The development of the control scheme was initiated by treating the scrubbing process as a grey system perceived as conceptual chemical dynamics. The scheme was implemented on a redundant programmable logic controller (PLC) and the control parameters were tuned based on responses from commissioning operations. The scheme, never re-tuned, has accomplished promising performance and consumable savings since its commission in the year 2000.