If burner shuts down, solenoid valves (NC) close and control flow oil pressure releases
from nozzle valve. Nozzle valve spring power closes nozzle needle valve and oil supply
from nozzle.
Post-purge
The post-purge position of servomotors is adjusted according to the fuel type. After
burner shutdown, servomotors drive to their post-purge positions. The fuel valves are
closed. The combustion air fan is running, to clear the combustion chamber of unburnt
fuel and products of combustion.
Burner start-up, pre-purge, ignition
During pre-purge, the burner fan ventilates the boiler and smoke flue. At the time, the
double solenoid valve is closed. The fan manages to create a full air pressure before
gas inlet. Air in the boiler and in the smoke flue will be circulated, which reduces the
pressure, developing in combustion chamber during flame ignition.
After the pre-purge, the servomotors run to the ignition position, the ignition begins,
and the double solenoid valve opens. Gas releases to the nozzle, and ignites by spark.
Ignition ends after time determined by the burner control. The flame burns with set
ignition load.
Burner operation
During burner operation, the capacity controller controls the burner control, which
controls the servomotors. Servomotors adjust the gas regulator valve and air dampers
between partial load and full load according to the capacity demand.
Burner shutdown
If burner minimum load exceeds the capacity demand of the boiler, burner shuts down
and gas valves close.
Gas valve proving
Gas valve proving is carried out with a switch, that tests double solenoid valve and
possible ignition gas valve tightness according to burner control program phase.
Pressure switch carries out gas valve testing during controlled shutdown or during next
prepurge period.
Post-purge
The post-purge position of servomotors is adjusted according to the fuel type. After
burner shutdown, servomotors drive to their post-purge positions. The fuel valves are
closed. The combustion air fan is running, to clear the combustion chamber of unburnt
fuel and products of combustion.
M5178 1647EN
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Summary of Contents for GKP-350 M
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Page 100: ...5 5 Time sequence diagram gas use Time sequence diagram G ver 3 98 129 M5178 1647EN...
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