Upgrade scrubbers to improve performance

This article examines why low SO{sub 2} allowance prices make it difficult to justify FGD upgrades as part of the compliance strategy, but in many cases, these upgrades still make good economic senses. Approximately 180 flue-gas desulfurization (FGD) systems are installed on utility boilers in the US> Many of these systems achieve nominal 70--80% SO{sub 2} removal efficiencies by operating at conditions to achieve stack SO{sub 2} emissions just below plant permit levels. This is generally done by treating a portion of the flue gas, and using the remainder to reheat saturated flue gas before discharging from the stack. Many of these systems are more than 10 years old, and can be upgraded to attain 95% SO{sub 2} removal. Incremental operating and maintenance (O and M) costs necessary to achieve 95% reduction are, in many cases,less than current allowance prices.