WNS Series horizontal Oil-fired (Gas) Boiler
-6-
control, process control, safety protection and so on. If the automatic system has trouble, can
start manual operation mode.
3.1 Water level control
The water level control system consists of electrode, relay, control circuit and so on. There
are electrodes with different size (long or short) inside water level controller and water level
alarm unit. When water level change, the electrode will contact with water or separate from
water to control water pump start or stop running through the relay and control circuit, so as to
realize the function of automatic feeding water, shut off water at too high water level, alarm
and stop running boiler at too low water level.
3.2 Pressure control
The pressure control consists of many (3 to 4) pressure controller and magnetic valve.
Working pressure can be control by multiple way, control the burning status according to the
different outside load. Adjust the differential and set point of pressure controller, can change its
dynamic property.
Now take rated steam pressure 1.0 Mpa as an example:
------ 1.04 Mpa (safety valve open);
------ 0.95 Mpa (alarm for high temperature, stop burning);
------ 0.9Mpa (stop burning);
------ 0.85 Mpa (run at low fire);
------ 0.8Mpa (run at low & high fire);
------ 0.7 Mpa (start burner).
3.3 Process control
For the process control, please refer to operation manual of burning unit.
3.4 Safely ignition protection
During boiler process controlling period, once finish pre-purging, will enter into ignition
process. Continue ignition for five seconds, if still can
’
t establish the flame inside furnace
because of some reasons, the photo resistance has no sense of light, stop burning and send out
acoustical & light alarm, continue post purging (for gas-fired boiler) then stop running boiler.
Check and find out causing reason and remove the trouble then can start boiler again,
3.5 Flameout protection
During running boiler, may suddenly happen to the phenomena of flameout inside furnace
because of some reason, the value of photo resistance will become larger, cut off supply oil and
gas, and send out acoustical & light alarm, continue post purging (for gas-fired boiler), then
stop running boiler. The boiler can start again only after removing the troubles.
3.6 Too low water level protection
During running boiler, while water level drops to the limit too low water level, stop burning
and send out acoustical & light alarm.
3.7 High water level protection
When boiler get to too high water level because of some reason, send out acoustical & light
alarm, must find out the causing reason in time.
3.8 Too high steam pressure protection
When steam pressure get to 98% rated steam pressure or get to 100% rate steam pressure,
should stop burning of boiler and send out acoustical & light alarm.
3.9 Photo resistance failure protection
The photo resistance is one of very important unit of burning control systerm, its property
will directly affect the safety for running boiler. So this control system has safety protection
measures.
When the value of photo resistance becomes small or when the photo switch is broken, the
relay contact inside control box will be off, burning can
’
t continue normally.
In additional, when stop running boiler or didn
’
t establish flame, if the indication lamp of
burning is on, it means that the photo resistance or photo switch has been broken, should
