specified capacity including an allowable service factor, and other
appurtenances necessary. Manual or automatic control and protective or
signal devices required for the operation specified, and any wiring
required to such devices, shall be provided whether indicated or not.
Where two-speed or variable-speed motors are indicated, solid-state
variable-speed controllers may be provided to accomplish the same function.
2.1.3
The plant shall include [package type] [field-erected type], [coal-] [fuel
oil-] [combination coal/fuel oil-] fired, controlled circulation, HTW
generators; expansion vessels; nitrogen pressurization system; makeup water
equipment; fuel systems; pumps; and all controls, piping, insulation,
miscellaneous plant equipment and other accessories indicated or necessary
to provide a complete and operable system.
2.1.4
HTW Generator Design Requirements
2.1.4.1
Radiant Heat Input
The radiant heat input for the effective radiant heating surface of
controlled circulation watertube HTW generators shall be limited to a
maximum of 394 kW/square meter 125,000 Btuh/square foot.
2.1.4.2
Maximum Heat Input
The maximum heat input per cubic meter cubic foot of furnace volume shall
be limited to 931 MJ/cubic meter 25,000 Btu/cubic foot with spreader
stokers and watertube boilers and 1,677 MJ/cubic meter 45,000 Btuh/cubic
foot with underfeed stokers.
2.1.4.3
The combustion gas temperature at the furnace exit shall be a [minimum of
56 degrees C 100 degrees F less than the ash fusion softening temperature
(reducing atmosphere) of the coal specified] [or] [maximum of 1150 degrees
C 2100 degrees F when furnace is oil-fired].
2.1.4.4
The HTW generator shall be of the controlled, forced-circulation,
watertube, once-through type designed and constructed for high temperature
water service, and shall be so certified by the manufacturer. Except as
modified, the design shall conform to the applicable construction and
performance requirements of ASME BPVC SEC I and ASME BPVC SEC VII with the
following additional requirements:
a.
The water pressure drop through the generator shall not exceed 105
kPa 15 psi based on a water temperature differential of 83 degrees
C 150 degrees F, generator inlet to outlet.
b.
The generator shall not have steam space or other spaces where
steam can be trapped. Headers shall be vented at high points as
required.
c.
be designed for horizontal flow or upflow of water.
d.
Tubes and headers located outside the primary radiant heat
SECTION 15555A
Page 18