OCR Text |
Show molecular nitrogen. Catalytic reduction requires expensive and relatively short-lived catalysts. It is relatively expensive, both in terms of initial capital and operating costs. Reagent addition, while potentially less capital intensive, is still much more expensive than the burners that are producing NOx· However, these high costs are frequently accepted to achieve the >90% NOx reduction that some of these systems can produce. The second way to reduce NOx is to modify the combustion process so that less is formed in the first place. This is very attractive since a typical catalytic reduction system can be an order of magnitude (or greater) more costly than even the most advanced low NOx burner. And, as will be seen below, burners by themselves can achieve the 90% reduction level. These burners offer a cost-effective alternative for systems where the high capital and operating expense of flue gas treatment is prohibitive. GRI's Industrial Combustion System NOx Reduction Strategy Because of the extremely high costs of post-combustion NOx reduction, GRI's Industrial Program has focused on modifying the combustion process to reduce NOx. The process of defining what should be done starts with segmenting the industrial market into high (> 1800° F), moderate (1000-1800° F), and low «1000° F) temperature process. (See Figure 4). The NOxformation NOx Emissions Reduction Strategy Proc.aa Temp. F HI Temp (>1800) Dlr.ctRrM Mid Temp (1~1800) 80""" LDw TemperaIJJte «1000) Food Proc:euing I >75 Uncontrolled NOK Eniaaiona, ppm ft"" 02 75-25 25-10 I:·:·:·:·:·:·:·:·:·:·:·:·:· ................................. ... . ...... . ..... . Pending Reguletlona RD&D Slelua: Cotnp/fIted On-Going I·:·:·.·:·:·:·····:·:··· J Figure 4 6 <10 ................................. .. .. ................................... . . . Mete} Reheeting. Forging. 2S2~ Heal Treeting, 224 Bd¥ GI ... ltfeltjng, 152 Bd¥ st..", GenerUon. 3,000~ ChetnicaJa. Be .• 1.1"~ Food Proc.aelng. S08c:OY Cu~g • 180~ |