c.
Hollow Concrete Stave Silos: Construct silo of precast concrete
staves with lateral air spaces. Cast staves from a well
proportioned mix of portland cement and an expanded clay light
weight aggregate. Minimum compressive strength of the concrete at
28 days shall be 34.50 MPa 5,000 psi. Hollow staves shall be 92
mm thick by 250 mm wide by 762 mm long 3 5/8 inches thick by 10
inches wide by 30 inches long with five lateral air cores per
stave, except that shorter starter staves may be used to permit
the horizontal joints to be staggered.
d.
Solid Concrete Stave Silos: Construct silo of solid lightweight
precast concrete staves. Solid staves shall be not less than 92
mm thick by 250 mm wide by 762 mm long 3 5/8 inches thick and 10
inches wide by 30 inches long, except starter staves may be
shorter. Solid staves shall be constructed from a well
proportioned mix of portland cement, washed sand and gravel which
is free from injurious organic impurities and contains less than 5
percent of deleterious substances. Grade the fine aggregate from
coarse to fine. Compressive strength of the solid concrete staves
at 28 days shall be 34.50 MPa 5,000 psi.
2.12.8
Pulse Jet Bag Filter Vent
**************************************************************************
NOTE: Consult the manufacturer of ash handling
equipment for venting requirements.
**************************************************************************
Provide for the silo constructed of 10 gage steel plate, fitted with rain
hood. Bag material shall be sateen cotton capable of withstanding not less
than 91 degrees C 195 degrees F, weighing 0.33 kg per square meter 9.75
ounces per square yard, having thread count of 4 by 2 per square mm 96 by
60 per square inch and permeability of 76 to 102 L/s 15 to 20 cfm per square
meter foot at 249 Pa one inch water column. Vent shall have not less than
[_____] square meter feet effective cloth filtering area, with each bag
having a maximum effective cloth filtering area of 0.56 square meter 6
square feet.
2.12.9
Rotary Ash Conditioner (Unloader)
Provide a complete dustless horizontal, floor mounted unloading device to
discharge ashes from silo to a [truck] [railroad car]. Unloader (ash
conditioner) shall include a 762 mm 30 inch diameter revolving drum which
rotates about fixed spray nozzles, and be complete with conditioner and
discharge compartments, scrapers, and other accessories as required.
Unloader drum shall be constructed of steel plate not less than 10 mm 3/8
inch thick and shall be roller chain driven by a totally enclosed, fan
cooled, [_____] volt, three phase, 60 Hz electric motor not less than 3.75
kW 5 hp as specified in paragraph entitled "Motors and Drives." Unloader
shall discharge conditioned ashes to a truck through a 6 mm 1/4 inch thick
steel plate chute. Unloader shall be designed to eliminate most dust when
in operation. Unloader may utilize screws as a means of mixing. Dustless
unloader shall add water to ash, but not to the extent that free or surplus
water is running or dripping from ash after discharge. Discharge ash shall
be in a semi-fluid, loose, free flowing condition.
2.12.10
Fluidizing System
**************************************************************************
SECTION 15501N
Page 116
Previous Page
