Refuse derived fuel incineration

There are numerous misconceptions about the sources of various chemical elements in waste, particularly those that are potential acid formers when the waste is incinerated or mechanically converted and used as a refuse-derived fuel. For example, it is often mistakenly stated that the source of chlorine in waste, hence a potential source of HCl emissions, is poly(vinyl chloride). The relative contents of selected, potentially acid-forming elements in the organic portion of a sample of waste collected from various households in one U.S. East Coast city is given in Table 2 (17). In this city, a chief source of chlorine in the waste is NaCl, probably from food waste. 

Four plants are reported to have considered burning TDF supplementally in boilers with a primary fuel of biomass or refuse-derived fuel. These plants are listed in Table 7-1. Two RDF fired power plants are attempting to obtain permits to bum tires.10 One biomass burner in Maine is reportedly in the permit process, and has been designed with the capability of burning tires.12 Personnel at the State Air Pollution Agency in South Carolina indicated that several municipalities had tried, unsuccessfully, in the past to bum TDF in their RDF incinerators.11 No information was obtained on boiler configuration or air pollution control equipment. 

The concentrations of TriCDTs, TeCDTs, and PeCDTs in soil and sediment samples, gas samples from waste incineration and aluminum smelting, ash from an aluminum smelting plant, a car shredder, and from combustion of wood chips, peat and refuse derived fuel, different effluents from a pulp and paper mill, and crab, carp, and lobster tissue samples, are presented in Table 1. 

Refuse Derived Fuel has significant potential for gasification applications since gasification docs not have such a negative public image as incineration and there is sufficient experience by TPS (26) and FOSTER WHEELER (12). However, the feeding systems for fluff RDF need to be developed further to ensure reliable operation and more experimental results at large scale applications are needed to prove efficient operation. 

Waste materials cover a diversity of products such as wood waste, used tires, waste from agricultural products such as rice husks, and municipal solid waste. Some of these waste materials are very heterogeneous while others are more uniform. Different types of waste are commonly processed using incinerators or reactors that process waste material by heat. The processed materials are commonly classified in char, liquid, and gasses. The municipal solid waste (refuse derived fuel), which is probably the most heterogeneous, is initially processed by the removal of metals, is shredded, dried, and pelletized, and only after that is it processed in heated reactors. 

The two leading methods of generating energy from the incineration of municipal solid waste (MSW) are the mass-bum system and the refuse derived fuel (RDF) system. The mass-burn system incinerates unprocessed MSW to recover energy and the RDF system processes unprocessed MSW into a usable fuel prior to incineration. Both methods use either starved-air modular, stoker grates, rotary kiln, or fluidized-bed units for incineration. While the mass-burn system is currently more widely utilized, both systems may be used for large waste capacities. 

In respect of operation of mass bum equipment for the incineration of municipal waste, Gunn [1990] has made some general comments in respect of fouling. He makes a comparison between refuse derived fuel (RDF) that has been densified (dRDF) by compression and a premium grade coal. His data are reproduced in Table 16.15. 

Because of the broad similarity to coal, tests to assess the potential for fouling (and/or slagging) have been based on those developed for coal, for instance the temperature indicators described in Section 16.3.2.1 Dabron and Rampling [1988] have given some ash fusion data for refuse derived fuel from three different UK incinerators and compared them with a coal as presented in Table 16.16. 

Thus, while there are a number of difficulties associated with the incineration of waste, the long-term prospects for this waste treatment process appear to be good and will impact upon both the medium- and long-term future of landfill. The incineration of refuse-derived fuel seems less certain. 

This extensive usage of lead has given rise to widespread environmental contamination. In rural areas ambient lead levels are usually below 0.2 jug/m in remote areas of the world one or two orders of magnitude below this, and in urban areas one order of magnitude above, with values up to 10 jUg/m not infrequently recorded in dense traffic. Over one-half and up to 90% of the airborne lead is derived from vehicle exhausts, the remainder from refuse incineration, fossil fuel combustion and from industrial sources such as smelters, iron and steel works and lead processing plants. 

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