In order for the system to operate this efficiently, a primary heat exchanger (normally a shell and tube type design) is placed on the 1400°F exhaust of the combustion chamber.
The recovered heat is then used to preheat the incoming process exhaust air to temperatures as high as 1200°F. Thermal efficiencies of the primary heat exchangers vary from 40% to 80% depending on the quantity of VOC's contained in the process exhaust coming to the unit. If the process air-stream contains 5% LEL, a 80% thermally efficient primary would typically recommended and at 25% LEL, a 40% thermally efficient unit would be used. The selection of the primary heat exchanger is carefully done to keep initial equipment and operating costs low. CEE engineers the system to develop the best fit for the customers' requirements. All Recuperative oxidizer systems produce waste heat that exits the final exhaust stack which can be recovered directly back to the process or a secondary heat exchanger can be used to recover the heat.
Controlled Environment Equipment has designed and installed Recuperative oxidizer systems with secondary heat recovery with LEL levels of 10-15% that allowed the overall system to operate without any additional fuel required. This is possible due to the fact the VOC's release heat when burned the same as fuel.