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Show ~5n Paper No. 12 ~ INTEGRATED MONITORING SYSTEM FOR CONTROL OF FOULING IN COAL-FIRED BOILERS by J.R. Wynnyckyj. R. Marr. E. Rhodes Department of Chemical Engineering University of Waterloo Waterloo. Ontario. Canada N2L 3Gl Slt1MARY Extensive heat transfer research in large coal-fired boilers using heat flux metering. pyrometry and mathematical modelling has produced an instrument and microco"l'uter system which allows the viewing of on-line colour coded screens indicating the whereabouts and degree of fouling of both the furnace and convection sections. By use of this system operators are able to strategically clean the boiler to maintain high efficiency and reduce downtime due to catastrophic fouling. SCOPE This paper describes the use of a microcomputer system for the observation and control of fouling in large-scale pulverized coal-fired boilers. The total system incorporates plant instruments. special instruments such as heat flux meters. pyrometers, thermocouples as well as the microcomputer, data acqui sition unit and operator di spl ays. Fundamental knowl edge of heat transfer incorporated in software algorithms allows the driving of video screens in such a manner that the operators can take remedial action to avoid losses due to fouling. LIGNITE-FIRED BOILERS In the operation of a pulverized coal-fired utility boiler, the losses due to problems caused by ash deposition can lead to significant expense. Typical costs due to ash-related losses for high fouling, low rank coal may be $8.4 million per year on a 500 M~ utility boiler (1). (These losses accrue from inefficient use of fuel, boiler shutdown and reduced load operation). Tests have been conducted on high fouling North Dakota 1 ignite with results showing that the power losses due to slagging and fouling range from 12.3 to 23.7% of boiler capacity (1). These inefficiencies result from increases in coal consumption, an increase in steam consumption for sootblowers and an increase in fan power requirements when gas paths are blocked by fouling deposits (2). |