1 October 1997
b. Effect of Moisture On Heating Value. Since moisture is in effect water, a nonburnable
component in the waste, it is important that the water content be kept to a minimum. All water in the
feed stock must be vaporized in the drying phase of combustion.
(1) Vaporization of water requires a nominal 1000 Btu/lb. Type-2 waste, containing 50% by
weight water, requires approximately 12% of its heating value to dry the waste, and another 10% to
raise the temperature of the water vapor to the required temperature for complete combustion.
(a) Where practical, the addition of moisture should be prevented by providing covers
on disposal containers to keep out rain and snow .
(b) Alternative methods for the disposal of wet mess-hall food waste and landscape
wastes will also help to improve the quality of the waste stream. Note the difference between the
as-discarded and the dry-basis values for the items listed in table 3-6.
(2) Table 3-7 shows the ultimate analysis of these same constituents. Table 3-8 shows
the ultimate analysis of some plastics commonly used in consumer products and containers and
compares them with fuels used in power generation and space heating.
c. Effect of Preprocessing and of Source Separation/Collection for Recycle Programs on the
(1) The practice of preprocessing waste to remove inert materials, many of which are
recyclable, is increasing as more communities and states are requiring waste stream recycling .
Materials separation plans are required by Federal regulations under 40 CFR Part 60 Subpart Eb,
Standards of Performance for Municipal Waste Combustors for Which Construction is Commenced
After September 20, 1994.
(2) Incinerator operators are finding this to be advantageous because it removes up to
20% of the waste that is nonburnable and which often creates ash-handling equipment difficulties.
(a) Processing the waste to produce an enhanced fuel product, called Refuse-Derived
Fuel (RDF), raises the fuel heating value.
(b) If the waste is processed for both optimization of recyclable materials recovery (i.e.,
remove recyclable paper, cardboard, and plastic) and fuel beneficiation (i.e., remove glass,
aluminum, steel and inerts), the heating value drops. The end product may now consist of only
43-55% of the original waste. Table 3-9 shows the effect of processing and materials
recovery/recycle on the heating value of waste.
a. Basic Chemistry. Incineration is an oxidation process, where organic constituents react with
oxygen and release heat during the process. Combustion may be defined as the rapid chemical
combination of oxygen with the combustible elements of a fuel.
(1) The two major combustible chemical elements of significance are carbon and
hydrogen. Chlorine and sulfur are usually of minor significance as sources of heat, but they
(primarily chlorine) are usually the major constituents concerning corrosion and pollution.