2.10.1
Bottom Blowdown Tank
The blowdown tank shall be fabricated of welded steel plate in accordance
with ASME BPVC SEC VIII D1. The tank shall be a vertical cylindrical tank
designed for the working pressure of the boilers. The tank shall be
equipped with a tangential blowdown inlet located so as to impinge on a 10
mm 3/8 inch carbon steel wear plate extending at least 180 degrees around
the interior circumference of the tank from the point of inlet. The tank
shall be equipped with an internal overflow, vent, drain, safety relief
valve, and gage glass with try cocks, blowdown cock, and guard. The
interior of the tank shall be protected by an epoxy coating system suitable
for continuous water immersion and operation at a minimum temperature of
[121] [149] degrees C [250] [300] degrees F. When buried, the tank [shall
be fitted [with renewable magnesium anodes] [with cathodic protection
equipment] to minimize galvanic corrosion.] [shall be constructed of Class
A reinforced concrete and shall be fitted with a bolted steel manhole frame
and cover. Install the blowoff pipe, vent pipe, and drain pipe in pipe
sleeves built into the concrete. Fill and calk the space between the pipe
and sleeves with lead wool or equivalent to make a watertight seal. The
tank shall be divided into two sections by means of a baffle to form a
sediment chamber.] Size and locate the blowoff tank as shown.
2.10.2
Sample Cooler
Provide a water-cooled, shell-and-tube or shell-and-coil type heat
exchanger designed for cooling sample of boiler water prior to chemical
testing. The sample cooler shall be furnished as a component of the
packaged continuous blowdown system when such a system is being furnished.
The cooler shall consist of a cast iron or steel shell with copper coil or
copper alloy tubes and shall be equipped with a brass or bronze sampling
cock. [The cooler shall be connected to a header and so valved that a
sample can be withdrawn from any boiler as desired.] [Furnish
concentrometer kit containing necessary glassware, reagents, and
instructions for determining boiler water concentrations.]
2.10.3
Continuous Blowdown System
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NOTE: Specify continuous blowdown only where makeup
water ratio is in excess of 20 percent of the boiler
output or where the total dissolved solids of the
makeup water are in excess of 500 ppm.
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NOTE: Include this requirement if a console type
unit is indicated.
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Provide a complete packaged unit of the automatic-proportioning,
[manual-apportioning] type wherein the amount of blowdown from the [boiler]
[plant] is automatically proportioned to the amount of make-up feedwater
[and the total amount of blowdown from the plant is manually apportioned
between boilers according to their steaming rate]. The system shall
include either an automatic-proportioning valve and a heat exchanger, or a
concentric tube automatic proportioning control which shall be provided
with a separate heat exchanger when necessary to meet the performance
requirements indicated or specified herein. The system shall be designed
for not less than boiler design pressure and shall be capable of heating
SECTION 15517N
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