shall be rated at 2690 watts per square meter 250 watts per square
foot, but shall be designed to operate at 2152 watts per square
meter 200 watts per square foot. Size all wiring, circuits, and
controls for 2690 watts per square meter 250 watts per square foot.
Total power density shall not be less than 4304 watts per square
meter 400 watts per square foot of heater module surface. Provide
hopper throat blanket heater with a single heating element.
Blanket element shall remain on during startup, offline, and
online operating conditions. Heating elements shall be made of
600 series stainless steel alloy or nickel-chrome alloy encased in
a minimum 20 gage aluminum or aluminized-steel mounting pan or
casing. Two sets of heater pigtails shall exit each module, one
set of pigtail for each element and circuit. Heater pigtail wires
and interconnecting wires shall be multi-strand copper wire with
high temperature (454 degrees C 850 degrees F) insulation.
Provide heater pigtails with strain relief fabricated in such a
manner as to prevent damage to the heater modules due to rough
handling. Pigtails shall be of sufficient length to reach the
terminal box. Splices shall not be permitted in pigtails from
modules, tapes, or blankets to the terminal box. Test each
module, blanket, or tape for electrical integrity at 1,000 volts
prior to installation. Heating units supplied shall have metal
labels firmly attached to the unit listing the wattage and voltage
of the unit. Heating units and mounting hardware shall be
fabricated of high temperature materials capable of withstanding
454 degrees C 850 degrees F. Insulate heating units with high
temperature woven glass cloth or mineral fiber. Mica or magnesium
oxide insulated heaters shall not be provided.
2.2.4.2
Hopper Heater Controls
Each hopper heater shall be thermostatically controlled with adjustable set
point and shall be furnished and installed complete including all power,
control, and alarm components. The thermostats for monitoring temperature
shall be 120 volt AC adjustable type mounted in NEMA ICS 6, Type 4
enclosures. For thermostatic control of the hopper heater system, the
Contractor shall provide a Master Hopper Heater Control Panel for the
Plant, a Local Hopper Heater Control Panel for the [boiler] [incinerator],
and a Local Hopper Heater Terminal Box at the hopper(s). The Contractor
shall furnish all materials, tools, and labor required for connections of
circuits and wiring between local hopper heater terminal boxes, local
hopper heater control panel(s), and the master hopper heater control
panel(s).
a.
Local Hopper Heater Terminal Box: On each hopper, provide
hot-dipped galvanized NEMA ICS 6 Type 4 hopper heater terminal
boxes with terminal blocks for connection of heater pigtails and
thermostat leads. Terminal blocks in each terminal box shall
contain a sufficient number of terminals to connect heater
pigtails and thermocouples.
b.
Local Hopper Heater Control Panel: Provide each [boiler]
[incinerator] with a local hopper heater control panel located in
the control room. Each local hopper heater control panel shall
contain: terminal blocks for power, control, and alarm circuits,
one control temperature thermostat, one low temperature alarm
thermostat, magnetic contactor and alarm relay with two normally
open contacts, and auxiliary relays for automatic operation of the
heater system. Provide a 3-pole fused switched main disconnect
SECTION 15861N
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