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Show 20 5. Fouling in the reheater follcws the same trends as the radiant superheater. Typically during normal periods of operation, sootblowing cleans the bank to a level of 10% fouled. Within two hours it becomes 30~ fouled. The upper two banks of the tubes, the pr;mary superheater end secondary superheater, foul rruch more slowly and only to about 20%. As a result they are typically cleaned only once every eight hours. 6. The economizer has been found to be as much as 30% fouled. Sootblowing is never conpl etely successful, a typical blow reduces the percent fouled from 25% to 15~. During badly foul ing periods sootblowing has 1 ittle or no effect on the economi zer. There may be considerable benefits to be gained if efficient sootblowing of the economizer could be obtained. Th e s i g n i f i can c e of t his wo rk ; s est a b 1 ish e d ; nth e f 011 Or.' i n g cos t benefi t ana lys is of the system. Proper use of the Ash ft>nitori ng System would realize savings in operating costs in the following areas: (i) increased availability (ii) fewer forced load reductions for deslagging (i ii) increased boiler capacity (i .e. MW) (iv) higher boiler efficiency (v) reduced steam consunption from sootblOtt'ing ACKNOWLEDGEMENTS The authors wish to thank the Canadian Electrical Association, Saskatchewan Power Corporation, Alberta Power Corporation, CKltario Hydro Corporat i on and the Nat i ona 1 Sci ence and Engi neeri ng Research Counci 1 of Ca nada. REFERENCE S 1. Honea, F.I., -Survey of Ash-Related Losses at Low-Rank Coal-Fired Ut ility Boilers", R.W. Bryers ed. Engineering Foundation Conference Foul ing and Sl agging Resulting from Irrpurities in Combustion Gases, Henniker, New Hampshire, 1981, pp. 527-539. 2. Jackson, P.J., Jones, A.R., -Fireside Fouling Experience in Large CEGB Soi 1 ers -, R.W. Bryers ed. Engi neeri ng Foundat i on Conference - Foul i ng and Sl a 9 gin 9 Re s u 1 tin g f rom I"l' uri tie sin Co m bu s t ion Ga s e s , He n n ike r , New Hampshire, 1981, pp. 1-15. 3. Gray, R.J., "bore, G.F., -Burning the SUbbituminous Coals of febntana and Wyomi ng ; n La rge lit i 1 i ty So i 1 ers", ASHE Pa per No. 74-WA/FU-1, New Yo rk, N. Y., 1974. 4. Wynnyckyj, J.R., Rhodes, E., Olambers, A.K., Furnace Wall Ash febnitoring System, U.S. patent 4,408,568, 1983. |