shafts shall pass through stuffing boxes equipped with packing rings and
lantern rings for seal water flow. Clinker grinder shall be provided with
a reversing mechanism to reverse direction of the grinder rolls should an
obstruction stall the grinder. A 9.5 mm 3/8 inch steel plate ejector feed
hopper shall be furnished below each clinker grinder to feed the inlet of
the pneumatic ash gathering system. Fixed passages in the clinker grinders
shall prevent discharge of particles too large to be handled by the
pneumatic conveying system. Each clinker grinder shall be driven by a
totally enclosed type motor and shall be provided with a reversing starter,
pressure switch for seal water control, diaphragm-operated seal water
valve, and a solenoid valve. Units shall be designed for the
characteristics of the coal specified and shall be capable of handling
bottom ash at a rate exceeding the conveying system capacity.
2.24.1.3
Conveyor Piping
Conveyor pipe and fittings shall be made of an abrasive-resisting alloy
metal cast by the sand-spun process, having a minimum Brinell hardness of
280. Wall thickness shall not be less than 13 mm 1/2 inch and pipe lengths
shall not exceed 5.5 m 18 feet. Joints shall be made with flanges or
sleeve pipe couplings and shall be air-tight. Fittings shall have a
Brinell hardness number of approximately 400 and shall be provided with
removable wearbacks, where applicable, or shall be of the integral wearback
type. Ash inlet fittings shall be designed so that the ash cannot overload
or clog the conveyor pipeline. Suitable adjustable supports or hangers
shall be provided. Vacuum hose connections shall be provided as indicated.
4.6 Meter Fifteen foot lengths of vacuum hose with quick connectors and
four floor sweep-up nozzles shall be provided.
2.24.1.4
Vacuum and Combination Vacuum/Pressure Systems
a.
Vacuum System: The ash conveying equipment shall be pneumatic
suction type, complete with vacuum pumps and all component parts
necessary for complete and successful operation. The ash
conveying equipment shall be sized approximately twice the
predicted accumulation rate. The system shall have the capacity
to convey and empty not less than [_____] metric tons/hour
tons/hour of ash weighing approximately [_____] kg/cubic meter pcf.
The tonnage shall be based on average handling rate and not on
the instantaneous rate.
b.
Combination Vacuum/Pressure Systems: Vacuum/pressure equipment
shall be commercially produced for this particular type of service
and shall include a pressure vessel equipped with a filter section
at the top and an aeration ring at the bottom. Material shall be
drawn into the unit by vacuum, with the air separated from the
material in the top filter section and exhausted through a
silencer. A high level indicator within the vessel shall then
reverse the action of the vacuum/pressure pump by aspirating air
through a silencer and filter unit and discharging the pressurized
air into the vessel. Part of the air shall be utilized to clean
the filter and part of the air shall pass through the aeration
ring of the vessel to pick up material and convey it under
pressure to the storage silo. The unit shall be furnished
complete with all automatic air control valves to control air flow
to and from the vessel continuously through the two modes of the
operating cycle. Unit operation shall continue automatically
until switched off at the control cabinet. All automatic valves,
interconnecting piping, and the vacuum/pressure vessel shall be
SECTION 15555A
Page 79
Previous Page
