Patent ID: 8881425

Claim:
A method for drying wood products with recovered flue gas comprising the steps of: providing an indirect fired kiln containing the wood products, the indirect fired kiln comprising: one or more chambers; one or more heating zones within the one or more chambers; one or more heating elements located in the one or more chambers; and a ventilation system; providing one or more combustion devices for heating a fluid in the one or more combustion devices, each of the one or more combustion devices comprising an exhaust stack, wherein the one or more combustion devices are selected from the group consisting of a steam boiler, a water boiler, and a thermal fluid heater; providing a heat exchanger within the one or more chambers in fluid flow communication in the one or more combustion devices; firing a fuel in the one or more combustion devices to heat the fluid and thereby producing a heated fluid and a flue gas from the one or more combustion devices; transporting the heated fluid from the one or more combustion devices to the heat exchanger and circulating the heated fluid in and the heat exchanger, thereby providing a primary heat source to the kiln; recovering an amount of the flue gas from the exhaust stack before the flue gas is discharged from the exhaust stack in each of the one or more combustion devices; transferring the recovered flue gas to one or more of the ventilation systems to provide a secondary heat source to the indirect fired kiln; and drying the wood products in the indirect fired kiln, a total heat source for the indirect fired kiln is provided by the primary heat source and the secondary heat source, wherein the primary heat source provides approximately 70% of the total heat source to approximately 80% of the total heat source, and wherein the secondary heat source provides approximately 30% of the total heat source to approximately 20% of the total heat source.