Investigating the Effects of Flue Gas Injection and Hot Water Distribution and Their Interaction on Natural Draft Wet Cooling Tower Performance

Abstract

This paper utilizes numerical modeling to address the effects of two parameters on natural draft cooling tower performance, namely the radial hot water distribution and flue gas injection. Predictions show that cold water temperature leaving the tower can be slightly decreased by increasing the weighting of the radial hot water distribution towards the tower periphery. The injection of scrubbed flue gas into the tower chimney can have either a positive or a negative effect on tower cooling performance, depending on the temperature of the flue gas relative to the temperature of moist air in the chimney. The temperature of the scrubbed flue gas is the primary variable affecting cooling tower performance, associated with flue gas injection. This paper investigates using the radial distribution of hot water to optimize the tower cooling performance when injecting scrubbed flue gas into the chimney, both for conditions when the flue gas is warmer and cooler than the temperature of moist air in the chimney. Predictions with no flue gas injection show that optimizing hot water distribution produced 0.4 °C reduction in cooled water temperature. With relatively cold (32.2 °C) and relatively hot (65.6 °C) flue gas injection, optimizing hot water distribution produced slightly more than 0.2 °C reduction in cooled water temperature.