1 October 1997
a. Purpose. The purpose of the following combustion calculations is not to design the
incinerator. The details of the incinerator design must be left to the manufacturer since the
manufacturer must guarantee its performance. However, information on heat release, gas
flow rates, particulate loading, and other pollutants in the flue gas will be needed in order to
prepare system performance requirements for the heat recovery boiler, pollution control
equipment, certain auxiliary equipment such as ID fans, and as input to an EIS. The data will
also be used to fill in the blanks on the flow and instrument diagram that the designer will find
among the standardized drawings.
(1) The combustion calculations described in this appendix are much more detailed
than those performed by the HRIFEAS computer program. HRIFEAS only calculates the heat
release and the amount of useful heat available based upon an assumed 55% thermal
efficiency for starved-air incinerators. The program does determine the optimum fit for the size
and number of incinerators to burn the available waste, based on the given operating schedule
and assuming an extra, redundant unit for maintenance and backup. In order to perform the
following combustion calculations, the characteristics, as well as the amount, of the waste
must have been determined during a waste survey as outlined in appendix A.
(2) The combustion calculations may be approximate or as detailed as the designer
feels is warranted by the requirements of the project and the accuracy of the waste
characterization. The effects of any material recovery performed on the waste stream must be
included because both noncombustible and combustible material will be removed. Most of the
combustion calculations will be in terms of mass or volume on a per-minute or per-hour basis.
B-2. HEAT RELEASED/RECOVERED.
a. Heat Content of Feed Stock.
(1) The waste characterization study should have determined the average heat
content of the waste in Btu per pound of waste on an as-received basis, including effects of
material recovery as noted above.
(2) The rate of release of the heat is based on the hourly rate of firing of the waste. If
35 tons of waste are to be burned in a 24-hour period, the rate of firing is as follows:
(35) (2,000 lb/ton) / (24 h/day) = 2,917 lb/h
If a shorter firing period is to be used, the numbers would be adjusted accordingly. This
information is also provided by the HRIFEAS program.