Heat generator

In a heat generator wherein a fuel, containing pollutants, is burned with an inflow of air to generate a hot combustion gas which exhausts as a flue gas at an elevated temperature and contains particulates and gaseous pollutants, the improvement comprising:

• heat exchange means for transferring heat from the flue gas to the inflow of air wherein the heat exchange relationship is selected so as to reduce the temperature of the flue gas from a transfer of heat therefrom to the inflow of air for enhanced thermal efficiency of the heat generator, with the temperature of the flue gas being reduced by said transfer of heat by the heat exchanger means to a level where at least one of said pollutants condenses out from the flue gas within the heat exchange means;
• and
• means for applying during said heat exchange a pollutant removing liquid onto said heat exchange means at a location selected to enable direct contact by the flue gas with said liquid for removal of pollutants and particulates from the flue gas and protection of said heat exchange means against corrosive effects of removed and condensed pollutants.

In a method for operating a heat generator in a large electrical power plant in which a fuel, containing pollutants, is burned with an inflow of air to generate a hot combustion gas in a boiler for heat exchange with a working fluid, and wherein the combustion gas is exhausted as a flue gas at an elevated temperature with particulates and gaseous pollutants and wherein the heat from the flue gas is passed to combustion gas in a preheater, the improvement comprising:

• passing the flue gas, after its passage through said preheater, and the inflow of air through a heat exchanger for the transfer of heat from the flue gas to said inflow of air for preheating thereof to a temperature selected to enhance the thermal efficiency of the heat generator;
• simultaneously applying pollutant removing liquid to the heat exchanger at a location enabling said liquid to remove from the flue gas, pollutants and particulate while protecting said heat exchanger from corrosive removed pollutants and particulates for an enhanced thermal efficiency of the heat generator in said large electrical power plant.

In a method for operating a heat generator wherein a fuel, containing pollutants, is burned with an inflow of air to generate a hot combustion gas which, after transfer of heat therefrom exhausts as a flue gas at an elevated temperature and contains particulates and gaseous pollutants, the improvement comprising the steps of:

• passing the flue gas and the inflow of air through a heat exchanger for the transfer of heat from the flue gas to said inflow of air for a preheating thereof;
• and
• simultaneously applying pollutant removing liquid onto the heat exchanger at a location enabling said liquid to remove, from the flue gas, pollutants and particulates while protecting said heat exchanger from removed corrosive pollutants and particulates without a significantly affecting the heat exchange process in the heat exchanger.