Alternative Water Screening for Thermal Power Plants

Since the early 1900s, virtually the only water screen used for power‐plant cooling water systems in the United States has been the “through‐flow” type of travelling screen. Trash bars and rakes upstream of the screens have been similarly restricted in design. Other industrialized countries of the world have gone their own separate ways in power plant water screening, having considerable confidence that they have the best. Serious and costly clogging and carryover of debris have plagued many U.S. installations over the years, but apparently not enough to push users to look at these other successful technologies. This paper explores the common alternatives to through‐flow screens, with comments on the pros and cons of performance, maintenance and cost. Some recent improvements to common U.S. screens will be discussed. Alternative trash rake designs will be similarly reviewed. Finally, this paper will discuss variations in the total water‐cleaning train.