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Show - 4 - Typical performance for this installation is shown in Table 1. As can be seen from this data, a NOx reduction of 50 % was achieved. The second type of glass furnace mentioned earlier is the recuperative type, illustrated schematically in Figure 8. This type of furnace differs from the regenerative type in that the flue gas flow is always in one direction. The hot flue gases flow from the melting tank through an exotic alloy or ceramic heat exchanger in series with a lower alloy heat exchanger and finally to the stack. The combustion air flows through these heat exchangers in the opposite direction. The temperature in the flue between the two heat exchangers is near the optimum for the THERMAL DeNOx process. The process has been demonstrated on a furnace of this type in west Germany with NOx reductions of 90 %. A THERMAL DeNOx system has recently been designed for a similar furnace in Southern California. Hydrogen addition will be used in this installation since the temperature out of the recuperator will be below the optimum for the THERMAL DeNOx process during most operating conditions. COST EFFECTIVENESS Table 2 shows the cost effectiveness for the application of the THERMAL DeNOx process to a hypothetical 100 MBtu/hr glass melting furnace. Our estimate of the total erected cost for a California location is shown first.. This estimate is for a system including an ammonia dissociator and a carrier air compressor, and represents our estimate of the material, labor and indirect costs, including engineering and overheads. The license fee is not included. The operating costs are shown next. Reagent consumption and cost is shown, along with an estimate of maintenance costs. An annual charge for the capital investment was calulated assuming 10 % interest over a 10 year period. An annual charge for the license fee was calculated in the same manner. These capital charges plus the operating costs yield the total annual cost. The cost effectiveness expressed in dollars per ton of NOx removed is calculated assuming a 60 % average NOx reduction. SUMMARY We have shown, by reference to several successful installations, that the THERMAL DeNOx process offers a proven and cost effective approach to significant NOx reduction for glass melting furnaces. Reductions of 60 to 90 percent have been demonstrated in these installations. In addition to the installations discussed herein, the THERMAL DeNOx process has been successfully applied to over 100 commercial units ranging from fired process heaters in the petroleum industry to coal fired utility boilers and MSW incinerators. |
