Boilers control systems

Boilers control systems

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The very best way to get redundancy in a steam boiler plant would be to have two completely independent one boiler control systems, and a good Marine Steam Boiler Control System should at least comprise the following:

  • Each boiler provided with a control cubicle with starters and stand-by functions for the fuel oil pumps and the feed water pumps. For each boiler two feed water pumps, and two fuel oil pumps etc.
  • Only a cable for the master/slave system between the two boiler control cubicles.
  • A master-slave system that forces the burners' load to follow the performance curves of the boilers. The master-slave function may be disconnected and allow the boilers to operate independently.
  • At inert gas firing the master burner's load is limited to operate between 50% and 100%. A steam dump controller should automatically take over the steam pressure control and by means of a control valve dump the excess steam to a steam dump condenser.
  • Install a ten minutes stop-delay on the combustion air fan motor to minimize the number of starts at low steam demand.
  • The burner forced to minimum firing if the boiler is cold or the pressure is lower than 1 bar.
  • Two set points for the water level; 40% level when the burner is stop and 50% when it's firing; to minimize shrink and swell at start and stop of the burner.
  • Supply for chemical dosing pump only when the feed water pump runs and the feed water control valve is open.
  • Separate automatic fuses for all, not short circuit proof, external circuits.

After some years of use the boiler control system ought to be optimized. Minor problems have led to adjustments and after a lot of small adjustments the system needs to be tuned up.
Modifying old boilers control systems might be very profitable measures.