Method and apparatus for optimization of feedwater heater liquid level
AssigneeNeundorfer, Inc.
InventorJoel B. Lantz
Life of this patent
Estimating the term…
Abstract
A processor controlled supervisory apparatus for a liquid level controller of a feedwater heater obtains DCA characteristics and breakpoints thereof in a programmed manner. A plurality of DCA characteristics are obtained for a plurality of load conditions, and the breakpoints and other operating parameters are stored in a database correlating operation parameters with load conditions. Equations describing the relationship between the parameters and the load conditions are determined by the programmed processor and additional data points determined therefrom to provide load-responsive control for liquid level setpoint. A retrofitting apparatus retrofits the inventive supervisory control apparatus onto existing liquid level controllers.
Claims29
A control apparatus for maintaining optimum water levels in a feedwater heater of the type including an outer shell and an internal tubing structure, for receiving and condensing into water in the shell, steam from a steam turbine for heating feedwater that is flowing through the tubing structure to a steam boiler which supplies steam to the turbine, and for discharging liquid water from the shell while maintaining certain water levels in the bottom of the shell and in a drains subcooler portion of said feedwater heater, said apparatus comprising:
- first means for storing, as a function of boiler load, breakpoint water level setpoint data and for calculating operating water level setpoint data from said breakpoint water level setpoint data, said breakpoint water level setpoint data having been determined from breakpoints of a plurality of curves, each representing a drains cooler approach temperature vs. water level setpoint characteristic for a predetermined boiler load;
- water level sensing means for providing water level data corresponding to water levels measured in the bottom of the shell of said feedwater heater;
- control means responsive to said operating water level setpoint data from said first means for receiving and responding to said water level data from said water level sensing means for controlling a discharge valve to discharge liquid water from the shell of said feedwater heater to control said liquid water level in the shell of said feedwater heater;
- and
- boiler load determining means for determining said boiler load and for providing boiler load data to said first means,
- said first means operable for establishing operating water level setpoints for said control means as a function of said boiler load data,
- thereby providing boiler load-responsive level control for said feedwater heater for optimizing operation thereof.
In a control apparatus for maintaining optimum water levels in a feedwater heater of the type including an outer shell and an internal tubing structure, for receiving and condensing into water in the shell, steam from a steam turbine for heating feedwater that is flowing through the tubing structure to a steam boiler which supplies steam to the turbine, and for discharging liquid water from the shell while maintaining certain water levels in the bottom of the shell and in a drains subcooler portion of said feedwater heater, control means responsive to water level setpoints provided thereto for controlling a discharge valve to discharge liquid water from the shell of said feedwater heater to control said water level therein and drains subcooler approach sensing means for providing drains subcooler approach temperature data, the improvement comprising:
- database generating means for generating a database correlating said drains subcooler approach temperature data as a function of said water level setpoints for predetermined boiler loads, including:
- storage means receiving said drains subcooler approach temperature data and storing said drains subcooler approach temperature data as a function of said water level setpoints;
- and
- incrementing means for providing an incremental adjustment to the water level setpoints;
- said incrementing means operable for providing a plurality of periodic incremental adjustments of said water level stepoints, said adjustments being spaced from one another by constant time intervals,
- said incremental adjustments being of magnitudes chosen to provide reduced perturbations in control stability of said feedwater heater and said constant time intervals being chosen to provide a condition approaching equilibrium in response to said incremental adjustment.
A method for optimizing water level in a feedwater heater of the type including an outer shell and a internal tubing structure for receiving and condensing into water in the shell steam from a steam turbine for heating feedwater that is flowing through the tubing structure to a steam boiler of the turbine;
- control means responsive to water level setpoints provided thereto for controlling a discharge valve to discharge liquid water from the shell of said feedwater heater to control said water level therein;
- and drains subcooler approach sensing means for providing drains subcooler approach temperature data, comprising the steps of:
- for a predetermined boiler load condition, periodically decrementing a setpoint for said control means, moving said setpoint at rates chosen to provide reduced perturbations in control stability of said feedwater heater,
- generating a database correlating said drains subcooler approach temperature data as a function of said water level setpoints for said predetermined boiler load condition thereby providing a curve of drains subcooler approach temperature data against water level setpoints, and
- for groups of said periodic decrements of said setpoints, comparing a function of a slope of the curve with a predetermined threshold therefor to determine a breakpoint of said curve thereby to determine a water level setpoint corresponding to said boiler load condition.
A method for optimizing control of a water level in a feedwater heater of the type including an outer shell and an internal tubing structure for receiving and condensing into water in the shell steam from a steam turbine for heating feedwater that is flowing through the tubing structure to a steam boiler of the turbine, control means responsive to water level setpoints provided thereto for controlling a discharge valve to discharge liquid water from the shell of said feedwater heater to control said water level therein, means for providing boiler load data signals identifying a boiler load condition, and drains subcooler approach sensing means for providing drains subcooler approach temperature data, comprising the steps of:
- receiving a boiler load data signal,
- responsively to said received boiler load data signal, accessing a database storing breakpoint water level setpoints as a function of said boiler load condition, said breakpoint water level setpoints having been determined from breakpoints of a plurality of curves, each representing a drains cooler approach temperature vs. water level setpoint characteristic for a predetermined boiler load,
- from said database, retrieving a breakpoint water level setpoint corresponding to the boiler load condition identified by said boiler load data signal,
- increasing the retrieved breakpoint water level setpoint to provide an operating setpoint containing a safety factor therein for a predetermined boiler load condition,
- providing an operating water level setpoint signal to said control means for establishing a water level corresponding to said boiler load condition.
A method for optimizing water level in a feedwater heater of the type including an outer shell and an internal tubing structure for receiving and condensing into water in the shell steam from a steam turbine for heating feedwater that is flowing through the tubing structure to a steam boiler of the turbine;
- control means responsive to water level setpoints provided thereto for controlling a discharge valve to discharge liquid water from the shell of said feedwater heater to control said water level therein;
- and drains subcooler approach sensing means for providing drains subcooler approach temperature data, comprising the steps of:
- for a predetermined boiler load condition periodically incrementing a setpoint for said control means, moving said setpoint at rates chosen to provide reduced perturbations in control stability of said feedwater heater,
- generating a database correlating said drains subcooler approach temperature data as a function of said water level setpoints for said predetermined boiler load condition thereby providing a curve of drains subcooler approach temperature data against water level setpoints, and
- for groups of said periodic increments of said setpoints, comparing a function of a slope of the curve with a predetermined threshold therefor to determine a breakpoint of said curve thereby to determine a water level setpoint corresponding to said boiler load condition.
A method for optimizing water level in a feedwater heater of the type including an outer shell and an internal tubing structure for receiving and condensing into water in the shell steam from a steam turbine for heating feedwater that is flowing through the tubing structure to a steam boiler of the turbine;
- control means responsive to water level setpoints provided thereto for controlling a discharge valve to discharge liquid water from the shell of said feedwater heater to control said water level therein;
- and drains subcooler approach sensing means for providing drains subcooler approach temperature data, comprising the steps of:
- for a predetermined boiler load condition periodically decrementing a setpoint for said control means, moving said setpoint at rates chosen to provide reduced perturbations in control stability of said feedwater heater,
- generating a database correlating said drains subcooler approach temperature data as a function of said water level setpoints for said predetermined boiler load condition thereby providing a curve of drains subcooler approach temperature data against water level setpoints, and
- for each of said periodic decrements of said setpoints, comparing a function of a slope of the curve with a predetermined threshold therefor to determine a breakpoint of said curve thereby to determine a water level setpoint corresponding to said boiler load condition.
A method for optimizing water level in a feedwater heater of the type including an outer shell and an internal tubing structure for receiving and condensing into water in the shell steam from a steam turbine for heating feedwater that is flowing through the tubing structure to a steam boiler of the turbine;
- control means responsive to water level setpoints provided thereto for controlling a discharge valve to discharge liquid water from the shell of said feedwater heater to control said water level therein;
- and drains subcooler approach sensing means for providing drains subcooler approach temperature data, comprising the steps of:
- for a predetermined boiler load condition periodically incrementing a setpoint for said control means, moving said setpoint at rates chosen to provide reduced perturbations in control stability of said feedwater heater,
- generating a database correlating said drains subcooler approach temperature data as a function of said water level setpoints for said predetermined boiler load condition thereby providing a curve of drains subcooler approach temperature data against water level setpoints, and
- for each of said periodic increments of said setpoints, comparing a function of a slope of the curve with a predetermined threshold therefor to determine a breakpoint of said curve thereby to determine a water level setpoint corresponding to said boiler load condition.
A control apparatus for maintaining optimum water levels in a feedwater heater of the type including an outer shell and an internal tubing structure, for receiving and condensing into water in the shell, steam from a steam turbine for heating feedwater that is flowing through the tubing structure to a steam boiler which supplies steam to the turbine and for discharging liquid water from the shell while maintaining certain water levels in the bottom of the shell and in a drains subcooler portion of said feedwater heater, said apparatus comprising:
- first means for storing, as a function of boiler load, operating water level setpoint data, said operating water level setpoint data having been determined from breakpoint water level setpoint data, said breakpoint water level setpoint data having been determined from breakpoints of a plurality of curves, each representing a drains cooler approach temperature vs. water level setpoint characteristic for a predetermined boiler load;
- water level sensing means for providing water level data corresponding to water levels measured in the bottom of the shell of said feedwater heater;
- control means responsive to said operating water level setpoint data from said first means for receiving and responding to said water level data from said water level sensing means for controlling a discharge valve to discharge liquid water from the shell of said feedwater heater to control said liquid water level in the shell of said feedwater heater;
- and
- boiler load determining means for determining said boiler load and for providing boiler load data to said first means,
- said first means operable for establishing operating water level setpoints for said control means as a function of said boiler load data,
- thereby providing boiler load-responsive level control for said feedwater heater for optimizing operation thereof.
A method for optimizing control of a water level in a feedwater heater of the type including an outer shell and a internal tubing structure for receiving and condensing into water in the shell steam from a steam turbine for heating feedwater that is flowing through the tubing structure to a steam boiler of the turbine, control means responsive to water level setpoints provided thereto for controlling a discharge valve to discharge liquid water from the shell of said feedwater heater to control said water level therein, means for providing boiler load data signals identifying a boiler load condition, and drains subcooler approach sensing means for providing drains subcooler approach temperature data, comprising the steps of:
- receiving a boiler load data signal,
- responsively to said received boiler load data signal, accessing a database storing breakpoint water level setpoints as a function of said boiler load condition, said operating water level setpoints having been determined from breakpoint water level setpoints, said breakpoint water level setpoints having been determined from breakpoints of a plurality of curves, each representing a drains cooler approach temperature vs. water level setpoint characteristic for a predetermined boiler load,
- from said database, retrieving a breakpoint water level setpoint corresponding to the boiler load condition identified by said boiler load data signal,
- providing an operating water level setpoint signal to said control means for establishing a water level corresponding to said boiler load condition.
Dependencies are inferred from the claim text.