The Influence of Fouling Build-up in Condenser Tubes on Power Generated by a Condensing Turbine

Abstract

After years of operation of a power-block condenser, even in systems equipped with common tube-side cleaning systems, the fouling build-up rate may increase and affect condensing turbine overall performance. In this paper, a CFD based estimation method was employed to study the effect of the thermal resistance of fouling on the power output of a condensing turbine unit. For old condenser tubes, a significant decrease in the power generated by the condensing turbine was observed. Compared to new tubes, the old ones have to be cleaned more frequently (up to 6 times) to maintain a power drop not exceeding 1 %. Correlation between fouling resistance and condenser inlet pressure was investigated numerically by adopting the continuum (porous zone) approach to condenser modelling. The estimation is based on experimentally determinedliterature data on the fouling build-up in a real power-block condenser. For very old condensers, fouling resistance after one year of operation (with tube-side fluid being seawater) may reach 0.0007 m2K/W. It was shown that such values of the fouling resistance result in turbine power drop up to 4.1 %, whereas with newcondenser tubes, reasonable values of the heat transfer coefficient can be maintained for 6 months and after one year of operation, turbine power drop does not exceed 1.5 %.