Steam temperature control in a boiler system using reheater variables
AssigneeEmerson Process Management Power & Water Solutions, Inc.
InventorsXu Cheng, Charles H. Menten, Richard W. Kephart
Life of this patent
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Abstract
A technique of controlling a boiler system such as that used in a power generation plant includes using manipulated variables associated with or control inputs to a reheater section of the boiler system to control the operation of the furnace, and in particular to control the fuel/air mixture provided to the furnace or the fuel to feedwater ratio used in the furnace or boiler. In the case of a once-through boiler type of boiler system, using the burner tilt position, damper position or reheater spray amount to control the fuel/air mixture or the fuel to feedwater flow ratio of the system provides better unit operational efficiency.
Claims37
A method of controlling a steam generating boiler system having a furnace, a superheater section and a reheater section, comprising:
- obtaining, at a controller, a first signal, the first signal being indicative of a desired value of:
- a reheater control variable, or
- a reheater manipulated variable,
- and the first signal being not indicative of a superheater spray setpoint;
- obtaining, at the controller, a second signal indicative of an actual value of:
- the reheater control variable, or
- the reheater manipulated variable;
- using the first signal in conjunction with the second signal to generate, by the controller, a third signal;
- and
- using the third signal in conjunction with a signal indicative of a firing rate to generate, by the controller, a fourth signal to control:
- a fuel feedwater ratio of the furnace and a boiler of the steam generating boiler system,
- a fuel/air mixture provided to the furnace, or
- an amount, a quanity or a type of fuel,
- to thereby control a steam temperature generated by the superheater section.
A controller unit for use in a steam generating boiler system having a boiler with a furnace, a superheater section and a reheater section, the controller unit comprising:
- a first input to receive a setpoint corresponding to at least one of a reheater steam temperature control variable or a reheater steam temperature manipulated variable, wherein the setpoint does not correspond to a superheater spray;
- a second input to receive a signal indicative of an actual value of the at least one of the reheater steam temperature control variable or the reheater steam temperature manipulated variable;
- a control routine that uses the signal indicative of the actual value of the at least one of the reheater steam temperature control variable or the reheater steam temperature manipulated variable and the setpoint associated with the at least one of the reheater steam temperature control variable or the reheater steam temperature manipulated variable to develop a first signal, and that uses the first signal indicative of a firing rate to develop a control signal;
- and
- an output to provide the control signal to the furnace to control:
- a fuel to feedwater ratio of the furnace and a boiler of the steam generating boiler system,
- a fuel/air mixture provided to the furnace, or
- an amount, a quantity or a type of fuel,
- thereby controlling a steam temperature generated by the superheater section.
A steam generating boiler system, comprising:
- a boiler having a furnace, a superheater section and a reheater section coupled to the superheater section;
- and
- a controller communicatively coupled to the boiler to control operation of the boiler, the controller being communicatively connected to the reheater section to receive a signal, the signal being indicative of a desired value of at least one of a reheater steam temperature control variable or a reheater steam temperature manipulated variable, and the signal being not indicative of a superheater spray setpoint and the controller including:
- a first routine that uses the signal indicative of the desired value of the at least one of the reheater steam temperature control variable or the reheater steam temperature manipulated variable to produce a first signal, and
- a second routine that uses the first signal and a second signal indicative of a firing rate to generate a control signal to be used to control:
- a fuel to feedwater ratio of the furnace and a boiler of the steam generating boiler system,
- a fuel/air mixture provided to the furnace, or
- an amount, a quantity or a type of fuel,
- thereby controlling a steam temperature generated by the superheater section.
A once-through boiler system, comprising:
- a furnace;
- a superheater section;
- a first turbine coupled to the output of the superheater section;
- a reheater section coupled to the first turbine;
- a second turbine coupled to the output of the reheater section;
- and
- a controller to control operation of the furnace, the controller being communicatively connected to the reheater section to receive a first signal, the first signal being indicative of a desired value of one of a reheater steam temperature control variable or a reheater steam temperature manipulated variable, and the first signal being not indicative of a superheater spray setpoint and the controller including:
- a first routine that uses the first signal and a second signal indicative of an actual value of the one of the reheater steam temperature control variable or the reheater steam temperature manipulated variable indicative of the reheater steam temperature control or manipulated variable to produce a third signal;
- and
- a second routine that uses the third signal and a signal indicative of a firing rate to produce a control signal, the control signal to be used to control:
- a fuel to feedwater ratio of the furnace and a boiler of the steam generating boiler system,
- a fuel/air mixture provided to the furnace, or
- an amount, a quantity or a type of fuel,
- thereby controlling a steam temperature at the output of the superheater section.
Dependencies are inferred from the claim text.