Method and apparatus for controlling the amount of reactant to be added to a substance using a sensor which is responsive to both the reactant and the substance

A method for controlling an amount of a reactant used to reduce a substance, such reactant being added to such substance to react with such substance, the product of such reaction along with un-reacted portions of the substance and un-reacted portions of the reactant being directed to a sensor, such sensor producing an output signal in response to detection of both the un-reacted portions substance and the un-reacted portions of the reactant, such method comprising:

• (a) changing the amount of reactant added to the substance;
• (b) measuring whether the output signal increases or decreases with the changed amount of reactant;
• (c) determining from the measurement whether the sensor is responding to the un-reacted reactant or to the un-reacted substance;
• and
• (d) adjusting the amount of the reactant added to the substance in accordance with the determination.

A method for controlling an amount of a reactant used to reduce a substance, such reactant being added to such substance to react with such substance, the product of such reaction along with un-reacted portions of the substance and un-reacted portions of the reactant being directed to a sensor, such sensor producing an output signal in response to detection of both the un-reacted portions substance and the un-reacted portions of the reactant, such method comprising:

• (a) periodically increasing and decreasing the amount of reactant added into the substance;
• (b) measuring changes in the output signal produced by the sensor from such periodical increases and decreases;
• and
• (c) integrating over each period a mathematical product of the periodically increasing and decreasing the amount of reactant with the measured change in output signal to produce a control signal, and
• (d) adjusting the amount of the reactant added to the substance in accordance with the control signal.

A processor for controlling reduction of a substance with a reactant, such reactant being added to the substance to react with such substance, the product of such reaction along with un-reacted portions of the substance and un-reacted portions of the reactant being directed to a sensor, such sensor producing an output signal in response to detection of both the un-reacted portions of the substance and the un-reacted portions of the reactant, such processor being programmed to:

• (a) change the amount of reactant added to the substance;
• (b) determine whether the output signal increases or decreases with the changed amount of reactant;
• and
• (c) determine from the measurement whether the sensor is responding to the un-reacted reactant or to the un-reacted substance.

A processor for controlling an amount of a reactant used to reduce a substance added to such substance to react with such substance, the product of such reaction along with un-reacted portions of the substance and un-reacted portions of the reactant being directed to a sensor, such sensor producing an output signal in response to detection of both the un-reacted portions substance and the un-reacted portions of the reactant, such processor being programmed to:

• (a) periodically increase and decrease the amount of reactant added to the substance;
• (b) measure changes in the output signal produced by the sensor from such periodical increases and decreases;
• (c) integrate over each period a mathematical product of the periodically increasing and decreasing the amount of reactant with the measured change in output signal to produce a control signal, and
• (d) adjust the amount of the reactant added to the substance in accordance with the control signal.