Maximal Heat Transfer Density in Heat Exchangers of Wet Flue Gas Desulfurization Equipment

Abstract

In this article, overall net heat transfer maximization for a cooler and reheater in the wet flue gas desulfurization equipment of coal-firing thermal power plant was explored. Constructal design was implemented such that optimal flow architectures in a finite volume of the cooler and reheater leading to maximal thermal performance were discovered. The flue gas outlet temperatures at the cooler and reheater are constrained between and in order to avoid acid condensation on the heat exchanger surface. A single water stream circulates through the cooler and reheater in order to absorb heat from the high temperature flue gas and to return heat to the flue gas again, respectively. It is demonstrated that the maximum overall net heat transfer is achievable and the relevant allocation of the heat exchangers can be configured depending on design constraints. The design constraints based on the flue gas temperatures are essential because acid condensation in the flue gas that takes place below the acid dew point can corrode the heat transfer surface and cause performance deterioration. Better performance is achieved when the design is endowed with more degrees of freedom.