||Pilot-scale investigation of closed-loop fly ash sluicing /
Litherland, S. T. ;
Nassos, P. A. ;
Owen, M. L. ;
Winton, S. L.
||Radian Corp., Austin, TX.;Environmental Protection Agency, Research Triangle Park, NC. Air and Energy Engineering Research Lab.
|| U.S. Environmental Protection Agency, Air and Energy Engineering Research Laboratory,
||EPA/600/7-85/021A; RAD-83-211-004-35; EPA-68-02-3163
Fly ash ;
Water reuse ;
Coal-fired power plants--Waste disposal--United States ;
Coal-fired power plants--United States--Waste disposal
Feedback control ;
Fly ash ;
Air pollution control ;
Solid waste disposal ;
Pilot plants ;
Electric power plants ;
Mathematical models ;
Closed loop systems ;
Coal fired power plants ;
Waste water reuse ;
||Some EPA libraries have a fiche copy filed under the call number shown.
||170 pages : illustrations ; 28 cm
The report gives results of a pilot-scale demonstration of the technical feasibility of closed-loop operation of fly ash sluicing systems. Chemical species leached from the ash increase the dissolved solids concentration of recycled sluice water to a point where equipment scaling may occur. Tests were conducted at two power plants using a 50-gpm pilot unit to demonstrate the feasibility of closed-loop operation, both with and without sluice water treatment. An ash sluice computer process model was developed to predict chemistry and process conditions in full-scale systems. Fly ash sluicing systems handling highly reactive alkaline ashes cannot be operated closed-loop without treating the sluice water to control scale formation. Adding acid to adjust pH was effective in controlling calcium carbonate scale formation in the sluice water return line; however, it increased the potential for gypsum scale formation. Gypsum was ultimately the limiting species which prevented reliable closed-loop operation at the plants tested. Increased ash/water contact time in a reaction tank was not adequate to control the potential for gypsum scale formation at the residence time tested. The ash sluice computer process model proved to be accurate in predicting the chemical composition and potential for scale formation in the pilot unit.
Caption title. "May 1985." "EPA/600/7-85/021." Microfiche.