1 October 1997
beneficiation of the waste by removal of certain components is not required (with the possible
exception of glass), bulk material still must be shredded, sized, and classified and thus is
considered a form of refuse-derived fuel (RDF). The status of commercial FBC technology using
RDF, though considered developmental for certain applications, does not have the satisfactory
third-generation experience that would make it a proven technology.
4-7. CO-FIRING OF REFUSE-DERIVED FUEL IN A COAL-FIRED BOILER.
a. Application. The destruction of processed refuse by co-feeding with coal into a coal fired
boiler is an option that has not been used at military installations in the past but has been well
demonstrated in the civilian sector
b. Operation. Typically, the co-firing of carefully processed waste (up to 20% by heat content)
with coal (80% by heat content ) has no significant detrimental effect on the performance of the
boiler, nor has it reduced the effectiveness of destruction of the waste. Waste processed to make
Refuse-Derived Fuel (RDF) with a 6,000-8,000-Btu/lb fuel value displaces bituminous coal at a ratio
of 1.5-2 tons of RDF for every ton of coal. When co-fired at 20% by heating value, 30-40 tons of
RDF would be burned for every 80 tons of coal consumed. This would mean that a 100,000 lb/h
steam boiler for a district heating plant that normally consumes 145 tons per day (tpd) of coal would
then burn 120 tpd of coal and 45-65 tpd of RDF. This 45-60 tpd of RDF would be produced from
90-120 tpd of waste generated at the base, before recycling.
c. Economics. Typically, the cost for constructing a facility to produce RDF has been 20-40%
of the cost for an incinerator. This option may be an effective solution if the base has a suitable
size and type of coal-fired district heating boiler. The drawback to using this technology is that the
RDF/waste stream would have to be matched to the minimum daily steam demand of the boiler,
thus assuring that the daily waste stream could always be processed and burned.
4-8. MEDICAL WASTE INCINERATOR. Medical waste incinerators fall into the category of special
applications of proven technology.
a. Technologies. Most incinerators used for the disposal of medical waste are of the
packaged, fixed-hearth, multiple-chamber, retort type, although some hospitals have installed a
single modular unit for the processing of all their waste. Most medical-waste-incineration operations
are extremely small (i.e., several hundred pounds per day). Rotary kilns have been used on larger,
b. Operation. The very small units will typically be located in the same area as the regular
hospital boilers. One of the existing boilers may be modified to recover the heat from the gases.
(1) Supplementary fuel burners are usually required to maintain the necessary
temperatures in both the primary and secondary chambers. If the waste steam has large amounts
of wet, Type 4 pathological waste, large quantities of auxiliary fuel will be needed to maintain the
temperatures required for safe destruction.