TM 5-810-15
(3) Construction. The pumps will be vertical
absorbed by the clean bearing cooling water and
shaft configuration with bottom suction. Replace-
transfer it to a circulating water system. The
able suction sideplates and rear sideplates will be
circulating water system may use river water, lake
provided.
water, or a cooling tower system where absorbed
(4) Pump materials. The ash sluice water re-
heat can be discharged. An evaluation must be
circulation pumps will be designed of abrasion
made to determine the feasibility of using a heat
resistant alloys to provide an acceptable life.
exchanger versus using a cooling tower where
e. Sludge return pump.
bearing water is directly pumped through the
(1) Application. The sludge pump is used on
cooling system. A plentiful supply of dirty water
a hydraulic ash handling system using a dewatering
from a lake or river may make a heat exchanger
bin. A tank or series of tanks collect and store the
more economical. Consideration will be given to
water discharge from the dewatering bins. Re-
water treatment as a cooling tower bearing water
maining ash particles settle in these conical shaped
system would have to be constantly monitored and
tanks and are pumped from the tank bottom back
treated as water is made up for evaporation.
b. Design. The heat exchanger must be sized to
to the dewatering bins by sludge return pumps.
(2) Design. The sludge return pumps have
transfer all the heat generated from the fully
the same design characteristics as the bottom ash
operational plant at the maximum continuous
pumps.
rating. Two heat exchangers will be used so one
can be removed from service, each having 100
percent of the flow capacity. The heat exchanger
7-14.
Bearing cooling water pumps.
will be designed to conform to the ASME Boiler
a. Application. Bearing cooling water pumps will
and Pressure Vessel Code, Section VIII. The heat
supply cooling water to all plant equipment with a
exchanger manufacturer must be given the infor-
cooling water demand. Typical equipment requiring
mation for both the shell side and the tube as
cooling water are pulverizers, pump bearings and
shown in table 7-11. The amount of cooling water
seals, air compressors and after coolers, fan drives,
required depends on the equipment cooling water
lube oil coolers and chemical feed sample coolers,
demand. The equipment manufacturers will be
asked how many gallons of cooling water per
Smaller boiler plants may have processed water
minute is required for equipment cooling at a given
available and may not require cooling water pumps.
inlet temperature of 95 degrees F allowing the
Boiler plants with a plentiful water supply will
outlet temperature to be no more than 10 degrees
sometimes allow cooling water to be discharged
F higher. The heater cooling water rated flow
without recirculation.
capacity will be the total equipment demand of all
b. Design. Two 100 percent capacity pumps will
equipment to be operating simultaneously plus a 20
be used to provide full backup. The required flow
percent design margin. The circulating water rated
rate needed is found by adding all equipment
flow capacity will be twice the cooling water rated
coincident demands. The future expansion of the
flow capacity.
plant will also be considered. The cooling water
system may be an open (once through) or closed
c. Construction. The coolers will be designed
(recirculating) type of system depending on the
and constructed to conform with the ASME Boiler
availability of clear water. The system head re-
and Pressure Vessel Code, Section VIII. The
quired must be determined by adding the system
piping friction losses and the static head required.
Table 7-11. Heat Exchanger Design Information.
When the flowrate and total head required are
known, add 10 percent tot he total head for wear
Typical Values
allowance. This will be the rated capacity and total
Shell Side
Tube Side
dynamic head for the pump selection.
Cooling Water
Water
c. Construction. The pumps will be motor
Number of passes
.1
1
driven, horizontal, vertical split case, end suction,
Temperature in, degrees F
115
85
centrifugal type, back pullout configuration, single
Temperature out, degrees F
95
95
stage design.
Flow gpm.
demand
demand
Maximum pressure drop,
2
5
7-15.
Bearing cooling water heat exchangers.
psi
a. Application. Bearing cooling water heat ex-
Design pressure, psig
150
75
changers are required for a closed loop system in
Fouling factor
.0005
001
which clean water is not available in unlimited
Maximum velocity, fps
3.0
5.0
quantities. A heat exchanger will transfer heat
7-14
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