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Show \0 Paper No. 18 ASH CONDITIONING FOR IMPROVED ESP PERFORMANCE M. Mozes, R. Mangal and R. Thampi Ontario Hydro Research Division 800 Kipling Avenue Toronto, Ontario. M8Z 5S4 ABSTRACT ,AlU~ Ash conditioning studies have been conducted at Ontario Hydro's 640 MJ/h combustion research facility to reduce high ash resistivities and improve ESP collection efficiencies when burning a low sulphur western Canadian (Luscar) coal, a western Canadian-US coal blend with limestone injection and a low sulphur eastern US coal. The Luscar coal produced a stable flame and carbon bUiBout was 99.9\1 Ash resistivities measured in situ ranged between 2 . 7 x 10 to 1.4 x 10 ohm.cm. The pilot precipitator performed only with 79% efficiency . S03 conditioning of the Luscar coal ash with 50 ppm S03 decreased the resistivity by 0.7 to 1 order of magnitude and improved the collection efficiency of the ESP. Conditioning the waste from the western Canadian US coal blend during limestone injection was carried out using both S03 and water. Injection of about 60 ppm S03 vapour into the flue gas to condition the limestone injection waste reduced the resistivity by up to 3 orders of ma~~itude. Humigification of the waste lowered ash resistivity from 2.8 x 10 to 1.8 x 10 ohm.cm. In both cases ash collection efficiency of the precipitator increased. Injecting a proprietary chemical to condition the ash from a 1.1% S eastern US coal had no effect on the ash resistivity but improved the cohesiveness of the ash causing a slight improvement in ESP performance . INTRODUCTION Ontario Hydro is committed to reduction of the level of acid gas emission from its coal burning plants. The main pollutants of concern are sulphur dioxide and nitrogen oxides. In December, 1985, the Ontario Government announced stricter acid gas emission limits for Ontario industries and Ontario Hydro's limits were reduced to 430,000 tonnes/year starting in 1986 and 215,000 tonnes/year starting in 1994. Nine nuclear units coming into service will reduce coal burns and acid gas emissions well below regulated limits into the early 1990' s. In the 1990' s uncertainties in load forecasts and the demand/supply options indicate that wide variation in coal burns are possible and various control technologies may be required/l/. For ~resentation at t he American Flame Research Committee 1988 Fall Intey,national Symposium . Coal : Fuel f or Today and f or the Future . Octc~er 4 - 6 ~ 19 88~ Pitt s burgh~ PA. |