(3)
Final Line Purge On/Complete
(4)
Baghouse Ash to Ash Silo
c.
Provide sensors such that the following items can be alarmed on
the ash handling system control panel annunciator [operator
interface console].
[(1) Blower Failure]
[(2) Blower High Temperature]
(3)
Bag Filter Failure
(4)
Bag Filter High Differential
(5)
Bag Filter Off
(6)
Plugged Hopper
(7)
Conveying Complete
[(8) Clinker Crusher Abnormal Shutdown
(1 required for each boiler)]
(9)
Low Conveying Air
(10) High Conveying Vacuum
d.
Vacuum Transmitter: To measure conveying system vacuum. Range
shall be zero to 101 kPa 30 inches mercury with 4 to 20 mA dc
linear transmitter output. Display vacuum on the ash handling
system control panel [operator interface console].
2.11.20.3
Operation
a.
Normally operated in the automatic mode. Automatically sequence
through the automatic intakes except [clinker crusher] [bottom ash
intake] for each boiler after system is started. When a unit is
not in operation, selecting the "bypass mode" shall cause intakes
on that unit to be skipped. For manual operation, "index" is used
to select the desired intake. As conveying system shuts down
automatically, main conveyor line shall be purged for
approximately one minute to remove ash remaining in it.
b.
Sequence system under control of vacuum switches and timers.
Maximum vacuum will be when system is conveying material. When a
hopper is empty, vacuum will drop and a "no load" vacuum switch
shall cause system to shift to the next intake. Prevent premature
sequencing due to momentary low vacuum with a timer. When a
plugged hopper occurs, vacuum will be between "no load" and normal
value. Provide a timer to allow packed or arched material to
break loose before alarming the condition.
c.
Provide solenoid air valves for each air operated device, timers,
contactors, relays and devices and equipment required for system
control, measuring and operation. Identify each device with an
engraved plastic identification plate [in accordance with a system
SECTION 15501N
Page 107
Previous Page
