Package Sludge Combustion for
Industrial Waste Treatment Plants
ROBERT J. SHERWOOD, Marketing Engineer
Water Management Systems
Dorr-Oliver Incorporated
Stamford, Connecticut
INTRODUCTION
By combining a unique sludge incineration method with established pretreatment steps and ash handling, smaller industrial waste treatment installations are
now more economically feasible. This package sludge disposal system, called
the FS Disposal-Type CR, is designed to receive a thickened degritted raw sludge,
about three to five per cent total solids concentration and produce an inert ash.
Five of these package units have been sold to date and one has been in operation
for fifteen months. This unique package sludge combustion system was officially
released for worldwide marketing last November.
The following features are what make the FS Disposal Type CR System well
suited to meet industrial sludge disposal problems: 1) Combustion of 200 lbs of
solids per hr can be accomplished in an area approximately 15 ft x 20 ft, much
smaller than current systems performing the same job; 2) Start up and shut down
costs are minimal, as the time required is less than 30 mins; and 3) The package
features standard unit design and highest quality construction material. Three
premounted sections provide for easy field connections and set up, and the unit
can be operational in a matter of days.
RICHARDSON BAY, CALIFORNIA INSTALLATION
The demonstration installation was sold to the Trestle Glen Sewage Plant in
Marin County, California. The unit disposes of the organic solids from a primary
and activated sludge treatment plant. The sludge combustion package consists of:
1) A long-bowl centrifuge for sludge dewatering; 2) A sludge combustion unit;
3) A scrubber -- dehumidifier; and 4) An ash concentration unit.
Figure 1 illustrates the arrangement of the Richardson Bay installation. Note
the relatively small area encompassed by the total system. The dimensions, including the working area, are 18 ft by 18 ft. At this plant, a three to four per
cent degritted sludge is fed to the MercoBowl Centrifuge. Here it is dewatered to
approximately 22 per cent solids and subsequently pumped into the reactor for
combustion. Fuel and air are added into the reactor. Combustion takes place and
the hot gases containing the inert solids are passed into a scrubbing unit. The
underflow from the scrubbing unit, a liquid ash slurry, is pumped to a hydro-
cyclone where the ash is removed and concentrated.
One of the most significant advantages with this kind of sludge combustion
system, is its economical startup and shutdown. Most sludge incinerators are not
economically suited to intermittent operation. In fact conventional combustion
systems rely on extended operation for their economies.
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