Abstract: A system and method of reducing SO2 emissions of a carbonaceous fuel fired hot gas stream in a system including a precipitator by injecting trona into the hot gas stream prior to the gas stream being cooled by an apparatus such as an air heater.

Abstract: A ball type check valve is provided featuring a simple rugged structure which can be easily fabricated and finished to have excellent fatigue strength and resistance to the stresses of continually repeating pressure fluctuations. The key to the success of this valve is the basic monobloc body used therein. Thus, one single compact body block is fashioned with a longitudinal opening extending therethrough, the median portion of which is a smooth cylindrical bore designed to house the ball stop, biasing spring and associated movable valve parts while the approach sections of the opening leading thereto from either end are of larger cross-section. The valve is then completed by incorporating upstream and downstream tail pieces enclosed within said approach sections and held in end to end direct contact sealing relationship with annular shoulder areas at either end of said median portion by means of suitable back-up attachment devices engaged with said body block.