Acta Technica 105. (1993)
1-2. szám - Fodor, L.–Gősi, P.–Kostka, P.–Tóth, J.: On-load mechanical cleaning of heat exchangers by means of brushes
FODOR, L.-GÖSI, P.-KOSTKA, P.-TÚTH, J. X water velocity steam load, steam mass flow time Subscripts: C clean condition F fouled condition M value based on measurement CA calculated value о condition in case of parameters t , v , s о о о 1 condition in case of parameters t^, v^, s^ condition in case of parameters t , v , s X X X Introduction Damages due to fouling of the surfaces exposed to the coolant are significant in case of water-cooled heat exchangers. E.g. in case of steam turbine condensers of this type, the overall heat transfer coefficient decreases, a loss of vacuum takes place and as a result, the effective turbine output decreases with the steam consumption remaining unchanged. To reduce damages and to avoid breakdowns, it is necessary that the heatexchange surfaces be cleaned during operation. Use of the conventional cleaning methods necessitates that the heat exchanger to be cleaned be put out of service. In this case, the loss in electricity generation is often considerable. Chemical cleaning e.g. by continuous feed of chemicals to the coolant results in damages to the environment and the costs of chemicals are not negligible either. Because of these disadvantages, equipment for mechanical cleaning of heat exchangers during operation are being used increasingly. From among equipment of this type, ball-type and brush-type systems are most widely used. The advantage of continuous cleaning over periodical cleaning is illustrated in Fig. 1. In case of continuous cleaning, the overall heat transfer coefficient remains practically constant while in case of periodical cleaning, the initial value of the overall heat transfer coefficient can never be restored again (Fig. 1). Ball-type cleaning systems use balls made of elastic material, the size of which is adjusted to the inner diameter of the heat-exchange pipes. The balls are introduced with the cooling water and pressed through V s T