Output increase of conventional thermal power plants by the method of feed water bypassing feed water heaters

Abstract

This paper reports output increase of conventional thermal power plants by the method of feed water bypassing feed water heaters, in order to deal with tight supply-demand situation of electric power in our business area. A method to let a certain amount of boiler feed water bypass several water heaters was chosen, since thermal influence on the plants of this method is less than other methods. Then, we analyzed the relation between the output increase and the ratio of bypassing heaters prior to the first application, using a heat balance analysis program for conventional power plants that we developed before. As a result, an output increase of over 30 MW was observed under the condition of 20 % of the feed water flow rate bypassing four high pressure heaters in a conventional thermal power plant of 1000 MW output. The procedures of bypassing heaters method were established and discussed in detail. This method was applied to two actual thermal power plants on trial. As a result, output increase over 30 MW was observed respectively, and it almost equals that of the calculation. The thermal efficiency for the output increase was calculated to be more than thirty percent by the heat balance program. Consequently, this method is considered having a possibility for the practical use.