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Show • Municipal Waste • Sewerage Sludge • Delayed Coke • Fluid Coke • Char • Rock containing bitumen • Plastics • Paint Sludge Recently, the burning rate and attrition rate of various size anthracite culm feeds were studied in a 250,000 Btu/hr MSFBC flow reactor installed at the Riley Research Center. On a commercial scale, a number of waste materials have been co-fired with coal and peat in a 117,000 lb/hr MSFB boiler at the Kerry Co-op Dairy Factory in Listowell, Ireland. This has included woodchips, sawdust, 35% ash coal, and RDF (7). Currently, Riley Stoker is constructing a 200,000 lb/hr antllracite culm fired MSFB cogeneration project at Archbald, Pennsylvania. EMISSIONS Staged combution limestone injection, and the ability to recycle large quantities entrained solids, provide the MSFB process with effective means of controlling both NOx and S02 emissions. Low combustion temperatures and two stage combustion provide the potential for achieving significant reductions in NOx• Its two stage design, in which the lower dense bed is operated under fuel rich conditions, provides a strategy for burning highly nitrogeneous materials including any agricultural wastes. Three variables have been found to have a significant effect on MSFB NOx emissions: (1) primary zone stoichiometry, (2) primary zone residence time, and (3) primary zone gas temperature (8). The importance of each of these variables is shown ig Figure 8:- Coal-fired pilot plant data, as well as data from 50 x 10 Btu/hr field unit are presented for a wide range of operating conditions. Given sufficient residence time, under optim~m fuel rich conditions, NOx emission levels approaching 0.1 elbm/1is0s ionB tul evcaenl mbea y acnhoti evalewda. ys Hboew ethveer , moopste rdateisnigra balte thoep elroawtiensgt NOx condition, particularly in waste incineration systems. There are inherent tradeoffs between NOx emissions and good combustion efficiency. As shown in Figure 9, pilot plant and field data can also be used to study those variables which have a significant effect on S02 capture (9). In figure 9a the effect of gas residence time (combustor height) ana sorbent particle size are compared for various CatS ratio. Even though the combined effect of many operating parameters makes the direct comparison difficult, increased gas residence time results in 5 |
