1 October 1997
4-1. GENERAL DESCRIPTION.
a. Furnace type incinerators have the following classifications:
(1) Packaged Units - Packaged furnace-type units are generally the smallest and least
sophisticated. The controls are minimal, and an automated ash-removal system may not be
included. The unit comes completely shop-assembled. The primary combustion chamber has a
fixed hearth that may be either a solid surface or a grate. The capacity for these incinerators is
approximately 100-900 lb of waste/h (i.e., 1-10 tons/day).
(2) Modular Units - Modular, furnace-type units are larger than packaged units typically
having capacities of 20-75 tons/day per combustion chamber. The primary combustion chamber,
the secondary combustion chamber, the stack, the energy recovery heat exchanger, and the
waste-charging system are totally fabricated in the shop as separate modules. These modules are
shipped for final assembly and hookup in the field. Installation requires the construction of
foundations, erection of support steel structures and enclosures, the assembly of the modules, and
the final installation of the auxiliary systems (i.e., the instrumentation and control system, the ash-
handling equipment, the hydraulic power system, etc.). Typically, a modular incinerator facility has
two to four units in parallel.
(3) Field-Erected Units. These are usually the largest, most sophisticated, and most
efficient incinerators. With typical single unit capacities greater that 75 tons/day, major components
are too large to be shipped as modules. Basic parts are shop fabricated and shipped to the site.
These large units are meant to run continuously and due to capacity are required by law to have
elaborate pollution control systems. A unit with this capacity will have limited application to a military
installation, especially if the base has an aggressive materials recovery and recycle program. The
increased construction costs of a plant with a capacity exceeding 250-400 tons/day is offset by
higher efficiency and lower maintenance costs per ton of waste destroyed. The furnace type
incinerators denote stationary hearth system designs and include fixed solid-surface hearths, fixed
grate hearths, rocking grates, reciprocating grates, traveling grates and sliding tiered solid hearths.
Rotary hearths or fluidized-bed units are not included in the furnace type classification. Rotary-
hearth units and the fluidized-bed units are described in sections 4-5 and 4-6 as technology
systems that are unique and different from the more commonly used stationary-hearth-type furnace
b. Mode of Operation.
(1) Irrespective of the size classification (packaged, modular, or field-erected), the mode of
operation of the furnace used to destroy the waste (i.e., starved-air units [SAU] or excess-air units,
[EAU]) is often used as the primary basis for characterizing an incinerator system.
(2) The size of the combustion chambers will be affected by the mode of operation. Most
packaged and modular units operate in the starved-air mode because of the inherent simplicity of
primary combustion chamber design, the inherently lower emission of particulates that has allowed