A novel method of waste heat recovery from high temperature furnaces to create radiative flameless combustion
One of the largest heat losses in high temperature furnaces is the loss of flue gas enthalpy. Currently, up to 60% of the heating value of natural gas (or any other fuel) used in high temperature furnaces is lost via the flue gases. This work discusses the benefits and technology of re-circulating the hot flue gases back into the furnace to avoid the large heat loss and supplementing the flue gases with oxygen to maintain the desired oxygen concentration. The energy-savings benefits are derived from two factors: (i) recirculating the hot flue gases back into the furnace, and (ii) a reduction in the mass of flue gases due to the use of oxygen. In addition to these energy benefits, environmental benefits are derived from a reduction in NOx production. In fact, flue gas recirculation (FGR) is a common method used to control NOx in engines and furnaces. The simple heat recovery device described in this paper can: (i) economically capture greater than 50% of the energy lost via the exhaust gases, (ii) provide a long trouble-free operational life of the heat recovery device at a significantly reduced installation cost, (iii) provide a method to control NOx produced by the furnace by FGR recirculation, (iv) increase furnace gas radiation and hence productivity, (v) can be profitably employed even with the high temperature recuperator, (vi) can be profitably used with 100% oxygen furnaces, and (vii) will work with both batch and continuous furnaces.
American Flame Research Committee (AFRC)
Atreya, A., & Kezerle, J. A. (2009). A novel method of waste heat recovery from high temperature furnaces to create radiative flameless combustion. American Flame Research Committee (AFRC).