OCR Text |
Show During the combustion of HW or M5W, a number of air pollutants can be produced. These include both criteria pollutants and others, as follows: • Nitrogen oxides (NDx) • Carbon monoxide (CD) • Acid gases (HC1, 5D2, HF, 5D4) • Particulate matter • Me ta 1 s (As, Be, Cd, Pb, Hg, Ni) • Toxic organics (dioxin/furan, PAH, chlorinated benzene, benzene) The toxic organics, chlorinated dioxin and furans, have received most of the public attention, but the modern waste incinerator must be able to control emissions of all multimedia pollutants. The pollutant control scheme which effectively accomplishes this goal will undoubtedly be a combination of combustion control and air pollution control devices (scrubbers and particulate control). There are currently only local regulations which dictate the level of control of these pollutants from the MSW incinerators, but the standards imposed will undoubtedly be made more stringent in the fUture due primarily to public pressure. Federal hazardous waste incineration pollution standards and procedures currently focus on the organics in the waste stream, HC1 removal, and particulate mass emissions. However, the EPA is currently developing standards for metals emissions and carbon monoxide from boilers and industrial furnaces burning hazardous waste. These standards are expected to be extended to incineration in the near future. Local standards for NOx are also generally imposed on hazardous waste incinerators, especially in non-compliance areas such as California. There is theoretical evidence that gas cofiring can be used to minimize emissions of potentially toxic trace hydrocarbon species. However, the designers of MSW combustion systems may claim that the general design approach (refractory wall, overfire air, grate design, etc.) provides sufficient control. Consequently, it is necessary to establish that cofiring, in conjunction with sorbent injection, can also be used for acid gas control. In California, NH3 injection is cited as best available control technology for NOx control, but there are still questions related to its use. 6 ,I |