Patent ID: 9657943
Date: 2017-05-23
CPC Classifications: F23J,F28C,F28D,Y02P

Claim:
1. A system for reheating industrial plant flue gas using waste heat, the industrial plant having a working gas source, a furnace including a boiler and a heat source for heating the boiler that produces flue gas during operation, flue gas hot ductwork through which the flue gas circulates, the flue gas hot ductwork having at least one heat transfer wall, a wet flue gas desulfurizer operatively connected to the flue gas hot ductwork for treatment of the flue gas, a gas mixing zone for receiving and blending flue gas exiting the wet flue gas desulfurizer and the working gas, and a chimney stack for receiving the blended flue gas and working gas, the system including: a. a three sided working gas ductwork mounted to the flue gas hot ductwork such that the heat transfer wall of the existing flue gas hot ductwork serves as a fourth wall of the three sided working gas ductwork; b. wherein the working gas is circulated through the three sided channel and the thermal energy from the flue gas is transferred to the working gas through the heat transfer wall by conduction, convection and radiation; and c. wherein the hot flue gas is circulated through the wet flue gas desulfurizer for treatment and is then physically blended with the warmed working gas in the gas mixing zone to heat the flue gas above a flue gas vapor dew point of the flue gas prior to the combined gas mixture entering the chimney stack.