Process measurement and control
AssigneePhillips Petroleum Company
InventorsRobert W. Rutledge, Franklin D. Ganaway
Life of this patent
Estimating the term…
Abstract
In the measurement of a variable process parameter and control of the process in response thereto, the time derivative of a second order or higher lagged process measurement signal is utilized to provide predictive capability in generating a process variable signal, in generating a process control signal, and in controlling the process in response to the measured parameter. The system is particularly well adapted to control of a non-self-regulating process.
Claims27
Apparatus comprising:
- second or higher order lag means for accepting a process measurement signal and delivering in response thereto a lagged process measurement signal;
- differentiator means for accepting said lagged process measurement signal and delivering in response thereto a derivative signal representative of the time derivative of said lagged process measurement signal;
- and
- signal combining means for accepting said process measurement signal and said derivative signal and delivering in response thereto a process variable signal representative of the weighted sum of said process measurement signal and said derivative signal.
A method for generating a process variable signal, said method comprising:
- generating a process measurement signal representative of the value of a preselected process parameter;
- applying a second or higher order lag factor to said process measurement signal to produce a lagged process measurement signal;
- generating, in response to said lagged process measurement signal, a derivative signal representative of the time derivative of said lagged process measurement signal;
- and
- generating, in response to said process measurement signal and said derivative signal, a process variable signal representative of the weighted sum of said process measurement signal and said derivative signal.
A method for generating a process control signal, said method comprising:
- generating a process measurement signal representative of the value of a preselected process parameter;
- applying a second or higher order lag factor to said process measurement signal to produce a lagged process measurement signal;
- generating, in response to said lagged process measurement signal, a derivative signal representative of the time derivative of said lagged process measurement signal;
- generating, in response to said process measurement signal and said derivative signal, a process variable signal representative of the weighted sum of said process measurement signal and said derivative signal;
- comparing said process variable signal with a set point signal to produce a process variable error signal;
- and
- generating a process control signal bearing a predetermined relationship to said process variable error signal.
A method of controlling the air flow to an ammonia synthesis reaction, said method comprising:
- generating a first process measurement signal representative of the ratio of hydrogen to nitrogen entering the synthesis reaction zone;
- applying a second or higher order lag factor to said process measurement signal to produce a lagged process measurement signal;
- generating, in response to said lagged process measurement signal, a derivative signal representative of the time derivative of said lagged process measurement signal;
- generating, in response to said process measurement signal and said derivative signal, a process variable signal representative of the weighted sum of said process measurement signal and said derivative signal;
- employing said process variable signal as the variable input to a first controller producing a first process control signal in response to a comparison of said process variable signal and a preselected set point signal;
- and
- controlling the flow of air to said reaction zone in response to said first process control signal.
Dependencies are inferred from the claim text.