bin dischargers may be provided in lieu of the outside vibrators. A
manually-operated, dust-tight slide gate shall be mounted at the
termination of each bin cone to allow isolation of the equipment below for
maintenance.
2.9.2
Lime Slakers
The lime slakers shall be of the detention or paste type. The slakers
shall be designed for continuous operation at the required capacity.
Slaking temperature and slaking performance shall be automatically
maintained, so that at least 90 percent of the calcium hydroxide particles
formed are smaller that 2 microns in size, when lime quality is as
specified. Slakers shall be capable of slaking all grades of 20 mm 3/4 inch
pebble quicklime at a controlled temperature. Automatic controls shall be
provided to inject excess water into the slaking chamber should the
temperature exceed a preset limit. Slakers shall be provided with an
exhaust system to prevent water vapor from rising into the feeder
mechanism. The slakers shall be of all welded steel construction and shall
be completely dust-tight. Access covers for all compartments shall be
provided. Slakers shall be designed for ease of maintenance and shall be
capable of shutdown for up to 24 hours without requiring cleanout prior to
restart. Provide a hose connection at each slaker level for use by
maintenance personnel. Lime feeders shall be of the gravimetric or
volumetric type as required for compatibility with the lime slakers.
Feeders shall be designed to prevent flooding of the slakers with lime.
Feeders shall be capable of handling pebble quicklime, including fines.
Feeders shall be dust-tight and shall be provided with dust-tight,
stainless-steel inspection doors on the discharge side of the feeders.
Flexible connections shall be provided between the bin cone outlets and the
feeders. Feeders shall be provided with adjustable rate setters and
totalizers. Each lime slaker shall be provided with a positive means of
removing grit from the lime slurry prior to discharging the slurry to the
tank. The grit removal system shall include classifiers or screens or both
as required to remove any grit which could produce operational problems in
the slurry pumps, piping, valves, or atomizers. The grit removal system
shall include a means of rinsing the grit with water to minimize lime
carryover to the grit disposal bin. The degritted slurry shall flow by
gravity to the slurry tank. The grit shall be conveyed to a disposal bin
(bin provided by the Government) located on the lower level within the lime
system enclosure at a point accessible to a forklift truck. The Contractor
shall provide conveyors and chutes as necessary to discharge grit to the
disposal from a point not more than 1.83 meters 6 feet above the lower
level floor. A slurry storage tank shall be located beneath the slakers in
the lime system enclosure. The tank shall be constructed of 6 mm 1/4 inch
carbon steel. The slurry tank shall be designed with a minimum storage
capacity of one hour at the maximum slurry use rate. The tank shall be
covered to minimize contact of the slurry with air. The tank shall be
provided with heavy-duty, top-mounted turbine agitators of a quantity and
design as necessary to keep the slurry particles in uniform suspension
without vortex formation. Tank shall have internal baffles to promote
agitation. Agitators shall be interlocked with pump controls so that pumps
cannot start unless at least one agitator is on. The tank shall be
provided with level monitors required for proper system operation. Level
switches shall be electrode probe type. Bubbler-type level switches are
not acceptable. The tank shall be provided with all necessary inlet,
outlet, and overflow connections. The bottom of the tank shall be pitched
for drainage and provided with a cleanout easily accessible by maintenance
personnel. The Contractor shall provide additional slurry tanks as
required for his specific system design. Tanks furnished under this
SECTION 15864N
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