Economics of Feedwater Heater Replacement

Abstract

As feedwater heaters age, performance deteriorates and leaks invariably occur. In order to keep the heater functioning properly, and to avoid the possibility of water backing into the turbine and causing damage, the leaking tubes are plugged. Usually, the initially plugged tubes cause small, if any, deterioration of performance. Eventually, the number of plugged tubes significantly affects the overall cycle efficiency. This paper presents a straightforward method for calculating the economical time for repair or replacement, without the need for extensive heat balance calculations or special rules of thumb. While the analysis presented here, based on the useful energy concept, is used to solve an operating problem, the same methods can be readily applied at the design stage, and can be used on any other component in the power cycle as well.