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Show 2.3.3 Cost Estimates of capital and operating costs for catalytic systems are available but uncertain. Various suppliers providing cost information use differing assumptions regarding secondary costs such as startup, interest during construction, site-preparation, shipping, etc. Also most costs are based on Japanese installations where the scope of costs included and yen-to-dollar exchange rates used for estimates may not be included in the reported costs. Reported capital costs range from $10 to $130 per rated kw with operating costs from $0.15 to $0.40 per million* BTU fired. However, most of the cost estimates lie in the range of $20 to $80 per rated kw. The lower end of the cost range is more applicable to large new utility boilers. For industrial size units and retrofit application, the relative capital cost estimates are at the higher end of the range. A recent EPA study reported SCR capital costs of about $60 per kw and $0.22 per million BTU fired. For typical NOx emission levels of 0.2, 0.3 and 0.7 lb NO per million firing gas, oil or coal, respectively, the cost effectiveness for 90% NOx reduction are approximately $2,500, $1,600, and $800/ton of NOx reduced, respectively. These costs are very sensitive to catalyst cost and lifetime. Catalyst cost alone can be a major portion of the initial cash outlay (probably counted as an operating cost since it is expendable). Typical manufacturer guarantees are for one year with statements that longer life la expected. 2.4 . COMBINED AMMONIA SYSTEMS V Both Thermal DeNOx and SCR have been discussed in Sections 2.2 and 2.3. Thermal DENOx performance is limited by temperature variations, mixing,. and unit access which reduces process effectiveness and leads to ammonia breakthrough into the stack gas. SCR processes yield higher NOx removal efficiency but the cost is higher, especially for retrofits. A combination of the two processes might utilize some of the advantages of each. Ammonia could be used more freely in the Thermal process with breakthrough being utilized in the following catalyst. A much smaller catalyst bed would be required so space and pressure drop requirements could be minimized. The (9) only documented testing of this combined approach was presented by EPDC 4-24 P-233 |