Patent ID: 7654011

Claim:
In a process of reducing the VOC and CO emissions in dryer offgas that is discharged into the atmosphere from a moist organic product dryer and wherein the process includes recuperative thermal oxidizing apparatus having an input of dryer offgas and hot products of combustion from a combination furnace and mixing chamber that produces a hot gaseous output destined for atmospheric discharge, the improved steps of: a. introducing fuel and combustion air into a burner connected to the combination furnace and mixing chamber; b. combusting the fuel and combustion air in the combination furnace and mixing chamber; c. separating the dryer offgas into a first portion and a second portion; d. directing said first portion of the dryer offgas through the burner to facilitate recirculation of flue gas for NOx reduction, said first portion of dryer offgas being combusted along with the fuel and combustion air in the combination furnace and mixing chamber; e. bringing said second portion of the dryer offgas into indirect heat exchange relationship with the hot gaseous output from the thermal oxidizing apparatus within a primary heat exchanger to preheat said second portion of the dryer offgas; f. separating the preheated dryer offgas into a first portion and a second portion; g. recycling said first portion of preheated dryer offgas back to the dryer; h. directing said second portion of preheated dryer offgas to the combination furnace and mixing chamber; I. mixing the first portion of dryer offgas of step d, the second portion of preheated dryer offgas of step h, and the products of combustion of step b, in the combination furnace and mixing chamber; j. introducing the mixture into the thermal oxidizing apparatus, which increases the temperature of the hot gaseous output from the thermal oxidizing apparatus to a level which significantly decreases the VOC and CO content of said hot gaseous output from the thermal oxidizing apparatus; and k. discharging the hot gaseous output from the thermal oxidizing apparatus to the atmosphere after indirect heat exchange with said preheated second portion of the dryer offgas of step e.