Multiple boiler control system and method of operation

  • US 5,042,431 A
  • Filed: 04/09/1990
  • Issued: 08/27/1991
  • Est. Priority Date: 04/09/1990
  • Status: Expired due to Term
First Claim
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1. A boiler system for a medium to be heated, comprising:

  • a plurality of boilers each having a control input for receiving a signal effective to regulate the modulation level of the boiler as a proportion of its fully turned-on condition;

    means for providing a sense signal representing the temperature or pressure of the medium;

    means for providing a set point signal representing the desired temperature or pressure of said medium;

    means jointly responsive to said sense and setpoint signals for generating a DUTYCHANGE signal representing the amount of energy required to change the temperature of said medium to said desired temperature or pressure within a predetermined time; and

    means for selecting one of said boilers as the lead boiler;

    sequencing means for producing a plurality of control signals, each applied to the control input of one of said boilers, said control signals being produced in a predefined sequence starting with the lead boiler'"'"'s control signal when the total output of all boilers is to be increased in the reverse of said predefined sequence, when the total output of all boilers is to be decreased;

    means defining for each boiler a FIRING point corresponding to the minimum modulation of the boiler when it is turned on and a MOD point corresponding to a modulation level of said boiler at which an immediately subsequent boiler is in said predefined sequence enabled to be turned on, andmeans for inhibiting a boiler from being brought below its firing point, before the preceding boiler is brought below its MOD point.

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