The Dynamic Behavior of Once-Through Cooling Water Systems under Fouling Phenomena

Abstract

Fouling in condensers of thermal power stations can reduce their heat load, which increases the backpressure of the steam turbine and cause deleterious effects to the energy output. A complete analysis of the condenser behavior must handle the exchanger as an integrated part of an entire cooling system, which also encompasses hydraulic equipment such as the pumping system. This paper presents a computer simulation analysis of the behavior of a condenser affected by inorganic precipitation fouling in the water side. Instead of using a fixed ‘fouling factor’, a dynamic fouling model is incorporated in the overall thermal-hydraulic calculations in order to simulate fouling resistances over time during long term condenser operation, and their dependence on operating parameters such as water velocity and temperature. The mathematical model employed shows how the system performance is affected by the reduction of the overall heat transfer coefficient due to the deposit accumulation and also predicts the hydraulic impact of fouling, which increases the hydraulic resistance for the cooling water flow, resulting in different fouling rates in different tube rows and along each tube length. The condenser model is validated through its comparison with operating data of real power plants.