equipment being utilized. Finned tubes will not be
used for solid fuels.
**************************************************************************
Economizers shall be of a type normally provided by the boiler manufacturer
and shall include [finned tubes,] [bare tubes,] baffles and headers and
shall have provision for cleaning and tube bundle removal. At maximum
load, economizer exit water shall not be within 17 degrees C 30 degrees F
lower than saturation temperature. Materials shall be capable of
withstanding the maximum boiler exit gas temperature plus 28 degrees C 50
degrees F. Tubes shall conform to ASME BPVC SEC I. Overall design and
installation shall preclude cold-end corrosion under any load condition.
Economizer exit flue gas temperature shall not be less than 177 degrees C
350 degrees F and the tube metal temperature shall be above the maximum
flue gas dew point for the fuel being fired under all load conditions.
2.3.3
Air Preheaters
**************************************************************************
NOTE: The economizer or air preheater will be
selected to be compatible with any pollution control
equipment being used.
**************************************************************************
Air preheaters shall be of a type normally provided by the boiler
manufacturer and shall be recuperative, tube plate, or regenerative type
constructed of materials adequate to withstand the corrosion effects of the
flue gases. Overall design shall preclude cold-end corrosion of the air
preheater under any load condition. Temperatures of all metals in contact
with flue gas shall be above the flue gas maximum dew point temperature for
the fuel being fired under all load conditions. Control shall be by steam
preheat or by automatic bypass and shall be integrated with the combustion
2.3.4
Draft Fans
**************************************************************************
NOTE: Where induced draft fans are installed
directly after the heat recovery boiler, it may be
necessary to provide liners for scroll sheets and
rotor blades if the gases contain particulates in
excess of 229 mg per dry standard cubic meter (0.10
gr/DSCF). The fan design and construction will be
strongly influenced by the type of particulate
control device used and its location relative to
that device.
**************************************************************************
Induced draft centrifugal fans as specified shall be furnished as an
integral part of the boiler design. The unit shall consist of an
electrical motor driven centrifugal fan, a housing (scroll and side
plates), controls, guards and accessories. All components shall be
attached to a common base which shall include provisions for fastening to a
foundation. The unit shall be completely assembled, ready for installation
and operation. Fan assemblies shall be suitable for continuous boiler
draft operation to handle flue gases having temperatures up to 800 degrees
F. Fans shall comply with AMCA 99 standard applicable to centrifugal
furnace fans and shall be rated for flow rate, pressure, power, speed of
rotation and efficiency in accordance with AMCA 210 and ASME PTC 10. The
SECTION 15846A
Page 31
Previous Page
