Heat generator

A rotary air preheater for improving the efficiency of a heat generator wherein an inflow of air is used and gas is generated which exhausts as a flue gas at an elevated temperature and contains particulates and gaseous pollutants comprising:

• a rotary air preheater having a rotor with a plurality of heat-exchange elements, said rotor being mounted for rotation so as to move the heat-exchange elements in rotational sequence from an air side where the inflow of air passes to a flue gas side where the flue gas passes for a preheating of the air, said rotary air preheater being selected so that the heat exchange relationship between the inflow of air and the flue gas is sufficient to reduce the temperature of the flue gas from a transfer of heat therefrom to the inflow of air for an enhanced thermal efficiency of the heat generator, and with the temperature of the flue gas being reduced by said transfer of heat by the heat exchange elements to a level where at least one of said pollutants condenses out from the flue gas within the heat exchanger;
• means for directing a localized stream of wash liquid and neutralizing material at the axial end of the rotor where the flue gas enters and the air exits;
• means for moving the stream of wash liquid along a zone located at said latter axial end and in the vicinity of the region where a rotor in the heat exchanger leaves the air side or enters the flue gas side, said zone being further oriented to rinse the rotor as it is rotated past the stream of wash liquid;
• and
• means for rotating the heat exchanger at a speed that is sufficiently low so as to enable an effective drain down of wash liquid from the rotor prior to the reentry of wetted heat-exchange elements into the air side of the air preheater.

A method for improving the efficiency of a heat generator wherein an inflow of air is used and a hot gas is generated which exhausts as a flue gas at an elevated temperature and contains particulates and gaseous pollutants, comprising the steps of:

• passing the flue gas and the inflow of air into axial ends of rotary heat exchanger for the transfer of heat from the flue gas passing on one side to said inflow of air passing on another side for a preheating of the air by virtue of rotation of the heat exchanger, wherein the heat exchange relationship between the inflow of air and the flue gas is sufficient to reduce the temperature of the flue gas from a transfer of heat therefrom to the inflow of air for an enhanced thermal efficiency of the heat generator, and with the temperature of the flue gas being reduced by said transfer of heat by said heat exchanger to a level where at least one of said pollutants condenses out from the flue gas within the heat exchanger and wherein the ratio of the heat capacity of air, H.sub.a, to the heat capacity of the rotary heat exchanger, H.sub.r, is greater than about 0.05 at full load;
• during said heat transfer directing a stream of wash liquid at the axial end of the rotary heat exchanger where the flue gas enters and the air exits to remove particles and pollutants from heat exchange elements of the heat exchanger, with the amount of washing liquid being selected so that the ratio of the heat capacity of air, H.sub.a, to the heat capacity of the liquid, H.sub.L, is greater than about 0.2 at full load;
• during said heat transfer applying a stream of neutralizing liquid at previously wash liquid treated surfaces of the rotary heat exchanger and which previously wash liquid treated surfaces are at least almost essentially dried to form a dry layer of neutralizing material on the surfaces of the rotary heat exchanger after evaporation of the neutralizing liquid;
• and
• during said heat transfer moving the streams of wash and neutralizing liquids along a zone oriented to rinse the entire rotary heat exchanger as this is rotated past the streams of liquid.

A method for improving the operation of a heat generator wherein an inflow of air is used and a hot gas is generated which exhausts as a flue gas at an elevated temperature and contains particulates and gaseous pollutants, comprising the steps of:

• passing the flue gas and the inflow of air into axial ends of a rotary heat exchanger having a rotor for the transfer of heat from the flue gas passing on one side to said inflow of air passing on another side for a preheating of the air by virtue of rotation of the heat exchanger, wherein the heat exchange relationship between the inflow of air and the flue gas is sufficient to reduce the temperature of the flue gas from a transfer of heat therefrom to the inflow of air for an enhanced thermal efficiency of the heat generator, and with the temperature of the flue gas being reduced by said transfer of heat by said heat exchanger to a level where at least one of said pollutants condenses out from the flue gas within the heat exchanger;
• during said heat transfer directing a first localized stream of wash liquid and a neutralizing material at one axial end of the rotary heat exchanger where the flue gas enters and the air exits to remove particles and pollutants from heat exchange elements of the heat exchanger;
• during said heat transfer directing a second localized stream of wash liquid at the other axial end of the rotary heat exchanger where the flue gas exits and the air enters to remove particles and pollutants from heat exchange elements of the heat exchanger, said second stream of wash liquid being in substantial alignment with the first localized stream of wash liquid so as to limit the area of wetted surfaces of the rotary heat exchanger;
• during said heat transfer moving the first and second streams of wash liquid along a zone oriented to rinse the entire rotary heat exchanger as this is rotated past the stream of wash liquid;
• and
• rotating the heat exchanger at a speed selected sufficiently low to enable substantial drainage of liquid from wetted heat exchange elements prior to their reentry into the air flow side of the rotary heat exchanger, for an enhancement of heat exchange efficiency during exposure to said liquid stream.

A rotary air preheater for improving the efficiency of a heat generator wherein an inflow of air is used and a hot gas is generated which exhausts as a flue gas at an elevated temperature and contains particulates and gaseous pollutants comprising:

• a rotary air preheater having a rotor with a plurality of heat-exchange elements, said rotor being mounted for rotation so as to move the heat-exchange elements in rotational sequence from an air side where the inflow of air passes to a flue gas side where the flue gas passes for a preheating of the air, said rotary air preheater being selected so that the heat exchange relationship between the inflow of air and the flue gas is sufficient to reduce the temperature of the flue gas from a transfer of heat therefrom to the inflow of air for an enhanced thermal efficiency of the heat generator, and with the temperature of the flue gas being reduced by said transfer of heat by the heat exchange elements to a level where at least one of said pollutant condenses out from the flue gas within the heat exchanger;
• means for directing a localized stream of wash liquid at the axial end of the rotor where the flue gas enters and the air exits;
• means for directing a localized stream of neutralizing material at previously wash liquid treated surfaces of the rotary heat exchanger to form a dry layer of neutralizing material on the surfaces of the rotary heat exchanger after evaporation of the liquid;
• means for moving the streams of wash liquid and neutralizing material along a zone located at said latter axial end and oriented to rinse the rotor and coat it with neutralizing material as the rotor is rotated past the stream of wash liquid.