Small-buck change yields big-bang gain

A cost-effective way to reduce CO{sub 2} from operating coal-fired power plants is to improve combustion efficiency or, in other words, reduce heat rate. Stabilizing firing rate, furnace draft and air flow can improve the heat rate by 1 or 2% in most units. The 75 MW Unit 3 and 109 MW Unit 4 of Kentucky Utilities' Green River Generation Station had difficulty maintaining combustion control operations. To improve this, the strategy was adopted similar to that used at the sister unit Tyrone 3 developed for firing rate/throttle pressure stability to ensure that the boiler control remained on automatic at all times. The system logic transfers control of the furnace draft to the units' induced draft (ID) fans. The modifications improved temperature and pressure control as well as unit response while opacity excursion, NOx emission and heat rate decreased by 3% in Unit 3 and 5.4% in Unit 4. 1 photo.