Steam temperature control using model-based temperature balancing
AssigneeEmerson Process Management Power & Water Solutions, Inc.
InventorRobert Allen Beveridge
Life of this patent
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Abstract
A technique of controlling a steam generating boiler system having multiple superheater sections includes determining multiple control signals to control a temperature of output steam to a turbine. The technique uses a first control block to determine an offset value based on multiple input temperatures and a dynamic matrix control (DMC) block to determine input steam control signals based on an output temperature and an output temperature setpoint. The technique modifies one of the input steam control signals based on the offset value. The modified input steam control signal and the unmodified input steam control signal are provided to respective field devices to control the input temperatures and, as a result, the output temperature.
Claims30
A method of controlling a steam generating boiler system having two primary superheat sections forming a parallel connection to a final superheat section, comprising:
- obtaining, via a first temperature sensor, a first temperature of first input steam of the steam generating boiler system;
- obtaining, via a second temperature sensor, a second temperature of second input steam of the steam generating boiler system;
- obtaining, via a third temperature sensor, an output temperature of output steam generated using the first input steam and the second input steam, the output steam for delivery to a turbine;
- determining, via an input controller, an offset value in the form of a numerical quantity, the offset value being developed from a numerical, arithmetical difference between the first temperature and the second temperature;
- generating, via an output controller and a balancer, based on the output temperature and an output temperature setpoint, a first control signal having a first control value for controlling the first temperature and a second control signal having a second control value for controlling the second temperature;
- modifying, via a summer module, the first control signal by adding the offset value to the first control value or by subtracting the offset value from the first control value;
- controlling the first temperature according to the first control signal that was modified;
- and
- controlling the second temperature according to the second control signal.
A controller system for use in a steam generating boiler system having a first input superheat section and a second input superheat section forming a parallel connection to an output superheat section, the controller system communicatively coupled to a first field device and to a second field device, and the controller system comprising:
- a controller module including:
- a first input to receive a first temperature of first input steam of the first input superheat section,
- second input to receive a second temperature of second input steam of the second input superheat section,
- a third input to receive an output temperature of output steam generated by the output superheat section using the first input steam and the second input steam,
- a fourth input to receive an output temperature setpoint,
- an input controller having processing logic configured to determine an offset value in the form of a numerical quantity, the offset value being developed from a numerical, arithmetical difference between the first temperature and the second temperature,
- a control routine configured to:
- generate, via an output controller and a balancer, based on the output temperature and the output temperature setpoint, a first control signal having a first control value for controlling the first temperature and a second control signal having a second control value for controlling the second temperature, and
- modify, via a summer module, the first control signal by adding the offset value to the first control value or by subtracting the offset value from the first control value,
- a first output to provide the first control signal that was modified to the first field device to control the first temperature, and
- a second output to provide the second control signal to the second field device to control the second temperature.
A steam generating boiler system, comprising:
- a boiler;
- a first field device and a second field device;
- and
- a controller communicatively coupled to the boiler, to the first field device, and to the second field device, the controller including a routine that:
- obtains, via a first temperature sensor, a first temperature of first input steam to the boiler;
- obtains, via a second temperature sensor, a second temperature of second input steam to the boiler, and
- obtains, via a third temperature sensor, an output temperature of output steam generated by the boiler using the first input steam and the second input steam,
- determines an offset value in the form of a numerical quantity, the offset value being developed from a numerical, arithmetical difference between the first temperature and the second temperature,
- using a balancer module, generates, based on the output temperature and an output temperature setpoint, a first control signal having a first control value for controlling the first temperature and a second control signal having a second control value for controlling the second temperature,
- modifies, via a summer module the first control signal by adding offset value to the first control value or by subtracting the offset value from the first control value,
- provides the first control signal that was modified to the first field device to control the first temperature, and
- provides the second control signal to the second field device to control the second temperature.
A method of controlling a system having two parallelly-disposed flows connected to an output flow, comprising:
- obtaining, via a first sensor, a first measurement associated with a first input flow of the system;
- obtaining, via a second sensor, a second measurement associated with a second input flow of the system;
- obtaining, via a third sensor, an output measurement of an output flow generated using the first input flow and the second input flow;
- determining, via an input controller, an offset value in the form of a numerical quantity, the offset value being developed from a numerical, arithmetical difference between the first measurement and the second measurement;
- generating, via an output controller and a balancer, based on the output measurement and an output measurement setpoint, a first control signal having a first control value for controlling the first measurement and a second control signal having a second control value for controlling the second measurement;
- modifying, via a summer module the first control signal by adding the offset value to the first control value or by subtracting the numerical quantity of the offset value from the first control value;
- controlling the first measurement according to the first control signal that was modified;
- and
- controlling the second measurement according to the second control signal.
Dependencies are inferred from the claim text.