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Show satisfactorily, even if they couldn't be placed in the ideal positions. The experiences we got after one year's continuous operation are: • The coal store should be as big as possible, because in wintertime the frozen coal must be put at one side to reach the unfrozen coal underneath. • The hoppers and unloading facilities must be heated to avoid blockages during wintertime. • The mills, feeders and pipes must be made to withstand pressure surges up to 3.5 bars in today's recommendations. If there is a dust explosion, the pressure can reach 6.5 bars. The equipment will, if possible, be modified to withstand 7 bars. • Safe flame detections seem to be a difficult subject in a coal boiler. We have installed two IR-cells on each burner, and also two pyrometers to see the furnace temperature. After a few modifications they work acceptably, but still not totally reliably. • In the boiler the uncooled surfaces give slag disposals. If it is possible, no such surface should exist in the furnace. • For the fly ash transportation we have very good experiences from Fakts pneumatic transport system. Coal Conversion on Boiler 4 Boiler P4 is a pure oil fired once-through boiler, supplied in 1972 by Gebr. Sulzer AG, Switzerland. The boilers are of tower type with corner firing and a boiler bottom. Technical data for oil firing is shown in Picture No. 1. This boiler will be converted during this winter period (1982/83) and will be commissioned on coal in the summer of 1983. It is more difficult to convert this boiler, because we have to change the pressure part of the furnace. Instead of the flat bottom we have to dig about 2 meters down under the boiler and install a hopper. We also install 48 new wall-blowers in the furnace and 36 retractable in the superheater area. The oil burners have to be changed out to coal/oil burners, which need bigger holes in the corners. Therefore, we have to modify the walltubes around the burners. 5-12 |