Agenda - Council - 11/25/1980 - Laserfiche WebLink

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- 20 - DuSt RDF is the most advanced RDF form. Fluff ~DF is blended with an embrlttling agent (a chemical that hardens cellulose so that paper and cardboard will shatter upon impact) and pro- cessed in a heated ball mill until the product will pass a 100 mesh screen (0.15 mm). The product is homogeneous and is believed to exhibit the least variability of any RDF. Dust RDF consists primarily of small paper fiber platelets. Conse- quently, it behaves like a powder, can be stored in silos, and can be handled with conventional flour and pulverized coal handling equipment. It is important to recognize, however, that an explosion potential exists when dust RDF, mixed with air, comes into contact with a spark. This is not a ma]or' drawback to the system, because explosion-proof handling equip- ment and fixtures are routinely employed when handling coal dust and flour. Of particular interest, dust RDF can be slurred with oil and burned in conventional oil-fired boilers. Dust RDF has a higher heating value of 6,900 Btu- /lb. and contains 10 percent ash and two percent moisture. It appears to have unlimited shelf life. Finally, any of the three forms of RDF may be agglomerated or densified to form densified RDF (d-RDF). Coarse and fluff RDF agglomerate well in pelletizers, brlquetters, and extruders, but agglomeration of dust RDF requires a lignin binder and pro- cessing in a briquette. Waterwall Furnaces Municipal refuse is delivered to the facility and deposited on a tipping floor or in the storage pits from which it is trans- ferred to the furnace feed hopper. From the feed hopper, wastes are continuously drawn into the furnace where they are burned and heat is recovered. Waterwall furnaces are enclosed by closely spaced water-filled tubes. Water circulates through the tubes to recover heat radiated from the burning fuel bed. Integrally constructed (attached) waste heat recovery boilers generate steam while reducing the temperature of the exhaust gases. Heat is trans- ferred by convection from hot gases passing over boiler tubes in the convection section of the boiler. Thus, a marketable product is created while reducing the stack gas volume'and, consequently, permitting tn, use of smaller gas cleaning equipment. In the combustion process, oxy9en is required to b~rn the fuel and release heat. The combustion process can be improved con- s~derably by agitating tn. fuel bed. Agitation results in rapid ignition, effective mixing, and leveling of the fuel bed. These factors combine to assure that all refuse parti- cles will come in contact with air and thus increase the com- pletion of combustion and minimize the amount of residue to be disposed.