US3905873A — Control apparatus for fractionation tower

Claim 1

Independent Claim 247 words

FOR USE WITH A FRACTIONATION TOWER WHERE FEED AND HEAT FLOW INTO THE TOWER AND THE FEED IS DISTILLED AND SEPARATED INTO DISTILLATE AND BOTTOMS HAVING DIFFERENT PRODUCT SPECIFICATIONS, SAID DISTILLATE AND BOTTOMS FLOWING FROM THE TOWER, WITH A PORTION OFTHE DISTILLATE BEING RETURNED TO THE TOWER AS REFLUX, AND A PORTION OF THE BOTTOMS COLLECTING IN THE TOWER AND ESTABLISHING A LIQUID LEVEL IN THE TOWER WHICH FLUCTUATES WITHIN PREDETERMINED LIMITS, CONTROL APPARATUS INCLUDING: REFLUX CONTROLLER MEANS FOR AUTOMICALLY CONTROLLING THE REFLUX FLOW RATE, PRESSURE CONTROLLER MEANS FOR AUTOMICALLY CONTROLLING THE PRESSURE WITHIN THE TOWER, DISTILLATE CONTROLLER MEANS FOR AUTOMICALLY CONTROLLING HE DISTILLATE FLOW RATE, BOTTOMS CONTROLLER MEANS FOR AUTOMICALLY CONTROLLING THE BOTTOMS FLOW RATE, DIVIDER MEANS RESPONSIVE TO VARIATIONS IN THE FEED FLOW RATE AND FEED COMPOSITION FOR AUTOMIALLY CONTROLLING THE DISTILLATE AND BOTTOMS CONTROLLERS TO DJUST THE DISTILLATE AND BOTTOMS FLOW RATES AND THE RATIO BETWEEN THESE FLOW RATES SUCH THAT SAID DISTILLATE AND BOTTOMS MEET PRODUCT SPECIFICATIONS DESPITE VARIATIONS IN FEED FLOW RATE AN FEED COMPOSITION, AND OVERRIDE MEANS FOR AUTOMATICALY CONTROLLING THE MATERIAL BALANCE WITHIN THE TOWER, SAID OVERRIDE MEANS BEING RESPONSIVE TO THE FLUCTUATIONS IN THE LIQUID LEVEL, AND WHEN THE LIQUID LEVEL IS IN DANGER OF EXCEEDING SAID PREDETERMINED LIMITS, SAID OVERRIDE MEANS TERMINATING CONTROL OF THE BOTTOMS CONTROLLER MEANS BY THE DIVIDER MEANS AND CONTROLLING SAID BOTTOMS CONTROLLER MEANS AS A FUNCTION OF THE LIQUID LEVEL UNTIL SAID LIQUID LEVEL IS NO LONGERIN DANGER OF EXCEEDING SAID PREDETERMINED LIMITS.

Claim 2

Dependent Claim 247 words

FOR USE WITH A FRACTIONATION TOWER WHERE FEED AND HEAT FLOW INTO THE TOWER AND THE FEED IS DISTILLED AND SEPARATED INTO DISTILLATE AND BOTTOMS HAVING DIFFERENT PRODUCT SPECIFICATIONS, SAID DISTILLATE AND BOTTOMS FLOWING FROM THE TOWER, WITH A PORTION OFTHE DISTILLATE BEING RETURNED TO THE TOWER AS REFLUX, AND A PORTION OF THE BOTTOMS COLLECTING IN THE TOWER AND ESTABLISHING A LIQUID LEVEL IN THE TOWER WHICH FLUCTUATES WITHIN PREDETERMINED LIMITS, CONTROL APPARATUS INCLUDING: REFLUX CONTROLLER MEANS FOR AUTOMICALLY CONTROLLING THE REFLUX FLOW RATE, PRESSURE CONTROLLER MEANS FOR AUTOMICALLY CONTROLLING THE PRESSURE WITHIN THE TOWER, DISTILLATE CONTROLLER MEANS FOR AUTOMICALLY CONTROLLING HE DISTILLATE FLOW RATE, BOTTOMS CONTROLLER MEANS FOR AUTOMICALLY CONTROLLING THE BOTTOMS FLOW RATE, DIVIDER MEANS RESPONSIVE TO VARIATIONS IN THE FEED FLOW RATE AND FEED COMPOSITION FOR AUTOMIALLY CONTROLLING THE DISTILLATE AND BOTTOMS CONTROLLERS TO DJUST THE DISTILLATE AND BOTTOMS FLOW RATES AND THE RATIO BETWEEN THESE FLOW RATES SUCH THAT SAID DISTILLATE AND BOTTOMS MEET PRODUCT SPECIFICATIONS DESPITE VARIATIONS IN FEED FLOW RATE AN FEED COMPOSITION, AND OVERRIDE MEANS FOR AUTOMATICALY CONTROLLING THE MATERIAL BALANCE WITHIN THE TOWER, SAID OVERRIDE MEANS BEING RESPONSIVE TO THE FLUCTUATIONS IN THE LIQUID LEVEL, AND WHEN THE LIQUID LEVEL IS IN DANGER OF EXCEEDING SAID PREDETERMINED LIMITS, SAID OVERRIDE MEANS TERMINATING CONTROL OF THE BOTTOMS CONTROLLER MEANS BY THE DIVIDER MEANS AND CONTROLLING SAID BOTTOMS CONTROLLER MEANS AS A FUNCTION OF THE LIQUID LEVEL UNTIL SAID LIQUID LEVEL IS NO LONGERIN DANGER OF EXCEEDING SAID PREDETERMINED LIMITS.

Claim 3

Dependent Claim 32 words

The control apparatus of claim 1 including means for manually adjusting the ratio between the distillate and bottoms flow rates and for manually controlling the distillate, bottoms, reflux and heat flow rates.

Claim 4

Dependent Claim 52 words

The control apparatus of claim 1 including means calibrated to maintain the bottoms flow rate such that said liquid level is within said predetermined limits, and calibration means for said calibrated means which calibrates said calibrated means whenever the override means terminates control of the bottoms controller means by the divider means.

Claim 5

Dependent Claim 52 words

The control apparatus of claim 1 wherein the pressure controller means maintains the pressure within the tower essentially constant, said pressure controller means including means for controlling the heat flow rate so that said heat flow rate is changed in response to any incipient pressure changes to maintain tower pressure essentially constant.

Claim 6

Dependent Claim 33 words

The control apparatus of claim 1 where the reflux controller means includes means responsive to the reflux temperature for modifying the reflux flow rate as the reflux temperature deviates from a standard temperature.

Claim 7

Dependent Claim 23 words

The control apparatus of claim 1 where the reflux controller means includes means for establishing a maximum and a minimum reflux flow rate.

Claim 8

Dependent Claim 355 words

For use in a fractionation tower where feed and heat flow into the tower and the feed is distilled and separated into distillate and bottoms having different product specifications, said distillate and bottoms flowing from the tower, with a portion of the distillate being returned to the tower as reflux and a portion of the bottoms collecting in the tower and establishing a liquid level in the tower which fluctuates within predetermined limits, control apparatus including: reflux controller means for automatically controlling the reflux flow rate, said reflux controller means including means responsive to the reflux temperature for modifying the reflux flow rate as the reflux temperature deviates from a standard temperature, and means for establishing a maximum and minimum reflux flow rate; pressure controller means for automatically controlling the pressure within the tower, said pressure controller means including means for controlling the heat flow rate so that said heat flow rate is changed in response to any incipient pressure changes to maintain tower pressure essentially constant distillate controller means for automatically controlling the distillate flow rate; bottoms controller means for automatically controlling the bottoms flow rate; divider means responsive to variations in the feed flow rate and feed composition for controlling the distillate and bottoms controllers to adjust the distillate and bottoms flow rates and the ratio between the flow rates such that said distillate and bottoms meet product specifications despite variations in feed flow rate and feed composition; override means for controlling the material balance within the tower, said override means being responsive to the fluctuations in the liquid level, and when the liquid level is in danger of exceeding said predetermined limits, sAid override means terminating control of the bottoms controller means by the divider means and controlling said bottoms controller means as a function of the liquid level until said liquid level is no longer in danger of exceeding said predetermined limits; means calibrated to maintain the bottoms flow rate within said predetermined limits; and calibration means for said calibrated means which calibrate said calibrated means whenever the override means terminates control of the bottoms controller means by the divider means.

Claim 9

Dependent Claim 355 words

For use in a fractionation tower where feed and heat flow into the tower and the feed is distilled and separated into distillate and bottoms having different product specifications, said distillate and bottoms flowing from the tower, with a portion of the distillate being returned to the tower as reflux and a portion of the bottoms collecting in the tower and establishing a liquid level in the tower which fluctuates within predetermined limits, control apparatus including: reflux controller means for automatically controlling the reflux flow rate, said reflux controller means including means responsive to the reflux temperature for modifying the reflux flow rate as the reflux temperature deviates from a standard temperature, and means for establishing a maximum and minimum reflux flow rate; pressure controller means for automatically controlling the pressure within the tower, said pressure controller means including means for controlling the heat flow rate so that said heat flow rate is changed in response to any incipient pressure changes to maintain tower pressure essentially constant distillate controller means for automatically controlling the distillate flow rate; bottoms controller means for automatically controlling the bottoms flow rate; divider means responsive to variations in the feed flow rate and feed composition for controlling the distillate and bottoms controllers to adjust the distillate and bottoms flow rates and the ratio between the flow rates such that said distillate and bottoms meet product specifications despite variations in feed flow rate and feed composition; override means for controlling the material balance within the tower, said override means being responsive to the fluctuations in the liquid level, and when the liquid level is in danger of exceeding said predetermined limits, sAid override means terminating control of the bottoms controller means by the divider means and controlling said bottoms controller means as a function of the liquid level until said liquid level is no longer in danger of exceeding said predetermined limits; means calibrated to maintain the bottoms flow rate within said predetermined limits; and calibration means for said calibrated means which calibrate said calibrated means whenever the override means terminates control of the bottoms controller means by the divider means.

Claim 10

Dependent Claim 32 words

The control apparatus of claim 7 including means for manually adjusting the ratio between the distillate and bottoms flow rates and for manually controlling the distillate, bottoms, reflux and heat flow rates.

Claim 11

Dependent Claim 347 words

For use with a fractionation tower where feed flows into the tower and is separated into distillate and bottoms which flow from the tower, a portion of said bottoms collecting in the tower to establish a liquid level in the tower which fluctuates within predetermined limits, control apparatus comprising: means providing a control signal which changes as the feed flow rate or feed composition change; means providing a level signal proportional to the level of liquid as said liquid level fluctuates between said limits; first controller means responsive to the control signal for controlling the rate at which distillate flows from the tower; second controller means responsive to the control signal and the level signal for controlling the rate at which bottoms flow from the tower, said second controller means on receiving the control signal changing the bottoms flow rate as said control signal changes, and on receiving the level signal changing the bottoms flow rate as the level signal changes; and transmission means for transmitting the control signal to the first and second controller means and for transmitting the level signal to the second controller means, said transmission means including a. multiplier means calibrated to maintain the distillate and bottoms flow rates such taht said liquid level is within said predetermined limits, b. override means having a nonoperable and operable state, said override means in the nonoperable state preventing transmission of the level signal to the second controller means and in the operable state terminating transmission of the control signal to the second controller means and transmitting the level signal to the second controller means, said override means being in the nonoperable state when the relationship between the control signal and level signal indicates that the level limits are not in danger of being exceeded, and being in the operable state when the relationship between the feed flow rate and the bottoms level indicate that the level limits are in danger of being exceeded, and c. calibration means for the multiplier means for calibrating said multiplier means whenever said override means is in the operable state.

Claim 12

Dependent Claim 347 words

For use with a fractionation tower where feed flows into the tower and is separated into distillate and bottoms which flow from the tower, a portion of said bottoms collecting in the tower to establish a liquid level in the tower which fluctuates within predetermined limits, control apparatus comprising: means providing a control signal which changes as the feed flow rate or feed composition change; means providing a level signal proportional to the level of liquid as said liquid level fluctuates between said limits; first controller means responsive to the control signal for controlling the rate at which distillate flows from the tower; second controller means responsive to the control signal and the level signal for controlling the rate at which bottoms flow from the tower, said second controller means on receiving the control signal changing the bottoms flow rate as said control signal changes, and on receiving the level signal changing the bottoms flow rate as the level signal changes; and transmission means for transmitting the control signal to the first and second controller means and for transmitting the level signal to the second controller means, said transmission means including a. multiplier means calibrated to maintain the distillate and bottoms flow rates such taht said liquid level is within said predetermined limits, b. override means having a nonoperable and operable state, said override means in the nonoperable state preventing transmission of the level signal to the second controller means and in the operable state terminating transmission of the control signal to the second controller means and transmitting the level signal to the second controller means, said override means being in the nonoperable state when the relationship between the control signal and level signal indicates that the level limits are not in danger of being exceeded, and being in the operable state when the relationship between the feed flow rate and the bottoms level indicate that the level limits are in danger of being exceeded, and c. calibration means for the multiplier means for calibrating said multiplier means whenever said override means is in the operable state.

Claim 13

Dependent Claim 88 words

The control apparatus of claim 9 where means providing the control signal include means for automatically controlling the ratio between the distillate and bottoms flow rates for a feed of a given composition so that said distillate and bottoms meet predetermined product specifications, said ratio controlling means including means for detecting changes in the feed composition, and, in response to such changes, for altering the ratio between distillate and bottoms flow rates so that distillate and bottoms maintain said product specifications as the composition of the feed changes.

Claim 14

Dependent Claim 224 words

The control apparatus of claim 10 where the multiplier means include a summer having first and second inputs and an output, said summer generating a signal at its output which is a function of the difference between the signals at the inputs, and first and second multipliers each having first and second inputs and an output and each generating a signal at their respective outputs which is a function of the multiple of the signals at their Respective inputs, said summer having its output connected to the override means, so that with the override means in the nonoperable state the signal at the summer output is transmitted to the second controller means, said first multiplier having its output connected to the first input of the second multiplier and the first input of the summer, and having its first input connected to the means for monitoring the feed flow rate to receive the feed signal and its second input connected to the calibration means to receive a calibration signal from said calibration means, said second multiplier having its output connected to the first controller means and to the second output of the summer, and having its second input connected to the means for detecting changes in the feed composition to receive a ratio control signal for controlling the ratio of distillate to bottoms flow rates.

Claim 15

Dependent Claim 34 words

The apparatus of claim 11 where the first and second multipliers are calibrated to enable the output signal from the summer to discontinue flow of bottoms when the flow of feed has been discontinued.

Claim 16

Dependent Claim 90 words

The control apparatus of claim 11 where the means for detecting changes in feed composition include composition analyzer means for automatically analyzing separated product flowing from the tower to determine if the separated product meets product specifications and for generating a product signal indicative of said separated product composition, means in the tower for measuring the temperature and for generating a temperature signal, and means responsive to the product and temperature signals for generating the ratio control signal and sending said ratio control signal to the second multiplier second input.

Claim 17

Dependent Claim 25 words

The control apparatus of claim 13 where the ratio control signal generating means includes means for automatically regulating the amplitude of the ratio control signal.

Claim 18

Dependent Claim 25 words

The control apparatus of claim 14 including means for manually regulating the amplitude of the ratio control signal transmitted to the second multiplier second input.

Claim 19

Dependent Claim 32 words

The control apparatus of claim 14 including means for automatically switching to the manual means for regulating the ratio control signal amplitude whenever the product signal indicates that analyzer means has malfunctioned.

Claim 20

Dependent Claim 124 words

The control apparatus of claim 14 where the automatic amplitude regulating means includes a set point input for receiving the product signal, a measure input for receiving the temperature signal, and an output where the control signal is generated, said regulating means holding the amplitude of the ratio control signal constant when the temperature signal and product signal are equal, indicating that the distillate and bottoms flow rates are such that the distillate and bottoms meet product specifications, and changing the amplitude of the control signal when the temperature and product signals are unequal, such change in ratio control signal amplitude continuing until the ratio of distillate and bottoms flow rates is changed so that the temperature and product signals are restored to equality.

Claim 21

Dependent Claim 43 words

The control apparatus of claim 17 including means operable when said switching means switches the control of the ratio control signal to manual for transmitting to the set point input of the automatic amplitude regulating means a signal equal to the temperature signal.

Claim 22

Dependent Claim 383 words

For use with a fractionation tower where constituent light and heavy components of a feed comprising two or more materials having different boiling points are separated into distillate and bottoms, said distillate and bottoms flowing from the tower as two different streams of materials having different product specifications, with a portion of the bottoms collecting in the tower to establish a liquid level which fluctuates within predetermined limits, control apparatus comprising means providing a control signal which changes as the feed flow rate or feed composition change; means providing a level signAl proportional to the level of liquid as said liquid level fluctuates between said limits; first controller means responsive to the control signal for controlling the rate at which the distillate flows from the tower, said distillate flow rate changing as the control signal changes; second controller means responsive to the control signal and the level signal for controlling the rate at which bottoms flow from the tower, said second controller means on receiving the control signal changing the bottoms flow rate as the control signal changes, and on receiving the level signal changing the bottoms flow rate as the level signal changes; means for regulating the ratio between the distillate and bottoms flow rates including means responsive to changes in the feed composition for altering the ratio between distillate and bottoms flow rates so that the streams of distillate and bottom materials maintain said product specifications as the feed composition changes; calibrated means for maintaining the bottoms flow rate such that said liquid level is within said predetermined limits; means for transmitting the control signal to the first controller means; means for transmitting the control signal and level signal to the second controller means including override means having a nonoperable state preventing transmission of the level signal to the second controller means and in the operable state terminating the transmission of the control signal to the second controller means and transmitting said level signal to said second controller means, said override means being in the operable state when the relationship between the control signal and the level signal indicates that the predetermined level limits are in danger of being exceeded; and calibration means for the calibrated means which calibrates said calibrated means whenever said override means is in the operable state.

Claim 23

Dependent Claim 383 words

For use with a fractionation tower where constituent light and heavy components of a feed comprising two or more materials having different boiling points are separated into distillate and bottoms, said distillate and bottoms flowing from the tower as two different streams of materials having different product specifications, with a portion of the bottoms collecting in the tower to establish a liquid level which fluctuates within predetermined limits, control apparatus comprising means providing a control signal which changes as the feed flow rate or feed composition change; means providing a level signAl proportional to the level of liquid as said liquid level fluctuates between said limits; first controller means responsive to the control signal for controlling the rate at which the distillate flows from the tower, said distillate flow rate changing as the control signal changes; second controller means responsive to the control signal and the level signal for controlling the rate at which bottoms flow from the tower, said second controller means on receiving the control signal changing the bottoms flow rate as the control signal changes, and on receiving the level signal changing the bottoms flow rate as the level signal changes; means for regulating the ratio between the distillate and bottoms flow rates including means responsive to changes in the feed composition for altering the ratio between distillate and bottoms flow rates so that the streams of distillate and bottom materials maintain said product specifications as the feed composition changes; calibrated means for maintaining the bottoms flow rate such that said liquid level is within said predetermined limits; means for transmitting the control signal to the first controller means; means for transmitting the control signal and level signal to the second controller means including override means having a nonoperable state preventing transmission of the level signal to the second controller means and in the operable state terminating the transmission of the control signal to the second controller means and transmitting said level signal to said second controller means, said override means being in the operable state when the relationship between the control signal and the level signal indicates that the predetermined level limits are in danger of being exceeded; and calibration means for the calibrated means which calibrates said calibrated means whenever said override means is in the operable state.

Claim 24

Dependent Claim 385 words

For use with a fractionation tower, control apparatus for controlling the reflux, distillate, bottoms and heat flow rates in response to the feed flow rate, including reflux flow controller means; distillate flow controller means; bottoms flow controller means; heat flow controller means; each of said controller means having a set point input, a measure input, and a control signal output, said controller means holding the control signal at its output constant when the signals at their respective inputs are equal and responding to signals at their inputs which are unequal to change the control signals at their respective outputs to adjust the controlled process conditions until the signals at their respective inputs are restored to equal amplitude; means responsive to the reflux flow rate for generating a reflux flow signal proportional to the actual reflux flow rate and for transmitting this reflux flow signal to the measure input of the reflux flow controller; means responsive to the distillate flow rate for generating a distillate flow signal proportional to the actual distillate flow rate and for transmitting this distillate flow signal to the measure input of the distillate flow controller; means responsive to the bottoms flow rate for generating a bottoms flow signal proportional to the actual bottoms flow rate and for transmitting this bottoms flow signal to the measure input of the bottoms flow controller; means responsive to the heat flow rate for generating a heat flow signal proportional to the actual heat flow rate and for transmitting this heat flow signal to the measure input of the heat flow controller; means responsive to the feed flow rate for generating a control signal proportional to the feed flow rate and for transmitting this control signal to the set point inputs of the reflux, distillate, bottoms and heat flow controller means; means for controlling the reflux flow rate including means responsive to the control signal from the reflux flow controller means output; means for controlling the distillate Flow rate including means responsive to the control signal from the distillate flow controller means output; means for controlling the bottoms flow rate including means responsive to the control signal from the bottoms flow controller means output; and means for controlling the heat flow rate including means responsive to the control signal from the heat flow controller means output.

Claim 25

Dependent Claim 385 words

For use with a fractionation tower, control apparatus for controlling the reflux, distillate, bottoms and heat flow rates in response to the feed flow rate, including reflux flow controller means; distillate flow controller means; bottoms flow controller means; heat flow controller means; each of said controller means having a set point input, a measure input, and a control signal output, said controller means holding the control signal at its output constant when the signals at their respective inputs are equal and responding to signals at their inputs which are unequal to change the control signals at their respective outputs to adjust the controlled process conditions until the signals at their respective inputs are restored to equal amplitude; means responsive to the reflux flow rate for generating a reflux flow signal proportional to the actual reflux flow rate and for transmitting this reflux flow signal to the measure input of the reflux flow controller; means responsive to the distillate flow rate for generating a distillate flow signal proportional to the actual distillate flow rate and for transmitting this distillate flow signal to the measure input of the distillate flow controller; means responsive to the bottoms flow rate for generating a bottoms flow signal proportional to the actual bottoms flow rate and for transmitting this bottoms flow signal to the measure input of the bottoms flow controller; means responsive to the heat flow rate for generating a heat flow signal proportional to the actual heat flow rate and for transmitting this heat flow signal to the measure input of the heat flow controller; means responsive to the feed flow rate for generating a control signal proportional to the feed flow rate and for transmitting this control signal to the set point inputs of the reflux, distillate, bottoms and heat flow controller means; means for controlling the reflux flow rate including means responsive to the control signal from the reflux flow controller means output; means for controlling the distillate Flow rate including means responsive to the control signal from the distillate flow controller means output; means for controlling the bottoms flow rate including means responsive to the control signal from the bottoms flow controller means output; and means for controlling the heat flow rate including means responsive to the control signal from the heat flow controller means output.

Claim 26

Dependent Claim 145 words

The control apparatus of claim 20 including divider means responsive to variations in the feed flow rate and feed composition for automatically controlling the distillate and bottoms controllers to adjust the distillate and bottoms flow rates and the ratio between these flow rates such that said distillate and bottoms meet predetermined product specifications despite variation in feed flow rate and feed composition; and override means for automatically controlling the material balance within the tower, said override means being responsive to the fluctuations in the liquid level in the bottom of the tower, and when the liquid level is in danger of exceeding predetermined limits, said override means terminating control of the bottoms controller means by the divider means and controlling said bottoms controller means as a function of the liquid level until said liquid level is no longer in danger of exceeding said predetermined limits.

Claim 27

Dependent Claim 52 words

The control apparatus of claim 21 including means calibrated to maintain the bottoms flow rate such that said liquid level is within said predetermined limits, and calibration means for said calibrated means which calibrates said calibrated means whenever the override means terminates control of the bottoms controller means by the divider means.

Claim 28

Dependent Claim 52 words

The control apparatus of claim 22 wherein a pressure controller means maintains the pressure within the tower essentially constant, said pressure controller means including means for controlling the heat flow rate so that said heat flow rate is changed in response to any incipient pressure changes to maintain tower pressure essentially constant.

Claim 29

Dependent Claim 33 words

The control apparatus of claim 23 where the reflux controller means includes means responsive to the reflux temperature for modifying the reflux flow rate as the reflux temperature deviates from a standard temperature.

Claim 30

Dependent Claim 23 words

The control apparatus of claim 24 where the reflux controller means includes means for establishing a maximum and a minimum reflux flow rate.

Claim 31

Dependent Claim 32 words

The control apparatus of claim 25 including means for manually adjusting the ratio between the distillate and bottoms flow rates and for manually controlling the distillate, bottoms, reflux and heat flow rates.

Claim 32

Dependent Claim 115 words

Control apparatus for controlling separation of constituent components of a feed comprising two or more materials, said two components flowing from a separation zone as two different streams of materials having different product specifications, comprising means for controlling the flow rates of said components leaving said zone to establish a ratio between the flow rates for a feed of a given composition so that said separated materials meet said product specifications, and means for detecting changes in the feed composition and in response to such changes altering the ratio between the flow rates so that the streams of separated material maintain said product specifications and maintain the material balance as the composition of feed changes.

Claim 33

Dependent Claim 115 words

Control apparatus for controlling separation of constituent components of a feed comprising two or more materials, said two components flowing from a separation zone as two different streams of materials having different product specifications, comprising means for controlling the flow rates of said components leaving said zone to establish a ratio between the flow rates for a feed of a given composition so that said separated materials meet said product specifications, and means for detecting changes in the feed composition and in response to such changes altering the ratio between the flow rates so that the streams of separated material maintain said product specifications and maintain the material balance as the composition of feed changes.

Claim 34

Dependent Claim 56 words

The apparatus of claim 27 additionally including means for monitoring the rate at which feed flows into the zone and for providing a signal proportional to this feed flow rate, and means responsive to the feed flow rate signal which change the flow rates of separated materials in proportion to the changes in feed flow rate.

Claim 35

Dependent Claim 261 words

Apparatus for controlling the flow of reflux in a fractionation tower where a mixture of materials having different boiling points is distilled and a portion is withdrawn as distillate and a portion is returned to the fractionation tower as reflux, comprising controller means having a set point input, a measure input, and a control signal output, said controller means holding the control signal at its output constant when the signals at its inputs are equal and responding to signals at its inputs which are unequal to change the control signal at its output to adjust the reflux flow rate until the signals at its inputs are restored to equal amplitude; means for controlling reflux flow including means responsive to said control signal from the controller means output for changing said reflux flow as said control signal changes; means for monitoring the reflux flow rate and providing a signal proportional to this reflux flow rate; means for monitoring the reflux temperature and providing a temperature signal proportional to this temperature; means for monitoring the distillate flow rate and providing a signal proportional to distillate flow rate; and means for transmitting the reflux flow rate signal to the measure input of the controller means and for transmitting the distillate flow rate signal to the set point of the controller means, including means responsive to the temperature signal for modifying the input signal to the controller set point so that deviation in reflux temperature from a predetermined reflux temperature alters the signal to the controller set point input to compensate for this temperature deviation.

Claim 36

Dependent Claim 261 words

Apparatus for controlling the flow of reflux in a fractionation tower where a mixture of materials having different boiling points is distilled and a portion is withdrawn as distillate and a portion is returned to the fractionation tower as reflux, comprising controller means having a set point input, a measure input, and a control signal output, said controller means holding the control signal at its output constant when the signals at its inputs are equal and responding to signals at its inputs which are unequal to change the control signal at its output to adjust the reflux flow rate until the signals at its inputs are restored to equal amplitude; means for controlling reflux flow including means responsive to said control signal from the controller means output for changing said reflux flow as said control signal changes; means for monitoring the reflux flow rate and providing a signal proportional to this reflux flow rate; means for monitoring the reflux temperature and providing a temperature signal proportional to this temperature; means for monitoring the distillate flow rate and providing a signal proportional to distillate flow rate; and means for transmitting the reflux flow rate signal to the measure input of the controller means and for transmitting the distillate flow rate signal to the set point of the controller means, including means responsive to the temperature signal for modifying the input signal to the controller set point so that deviation in reflux temperature from a predetermined reflux temperature alters the signal to the controller set point input to compensate for this temperature deviation.

Claim 37

Dependent Claim 52 words

The apparatus of claim 29 including adjustable means for establishing high and low limits which control the transmission of the signal to the controller set point input such that said signal to said set point input must come within the high and low limits to be transmitted to said set point input.

Claim 38

Dependent Claim 327 words

For use with a process having at least three variable and interrelated conditions, one of said conditions being controlled, another of said conditions being uncontrolled and still another of said conditions being maintained within predetermined limits, control apparatus comprising; first means for monitoring the uncontrolled condition and providing a signal proportional to this uncontrolled condition; second means for monitoring the controlled condition and providing a signal proportional to this controlled condition; third means for monitoring the limited condition and providing a signal proportional to this limited condition; controller means having a set point input, a measure input, and a control signal output, said controller means holding the control signal at its output constant when the signals at its inputs are equal and responding to signals at its inputs which are unequal to change the control signal at its output to adjust the controlled process condition until the signals at its inputs are restored to equal amplitude; means for controlling said controlled process condition including means responsive to said control signal from the controller output, said controlling means changing said controlled condition as said control signal changes; means for transmitting the signal from the first monitoring means to the set point input of the controller means and for transmitting the signal from the second monitoring means to the measure input of the controller means; and override means having a nonoperable state and an operable state where the override means terminates transmission of the first monitoring signal to the controller set point input and transmits to said controller set point input the signal from the third monitoring means, said override means including means for comparing the signals from the third monitoring means with at least one of the signals from one of the other monitoring means and, when a predetermined relationship exists between compared signals indicating corrective action should be taken to maintain said limited condition within said predetermined limits, for switching the override means to the operable state.

Claim 39

Dependent Claim 327 words

For use with a process having at least three variable and interrelated conditions, one of said conditions being controlled, another of said conditions being uncontrolled and still another of said conditions being maintained within predetermined limits, control apparatus comprising; first means for monitoring the uncontrolled condition and providing a signal proportional to this uncontrolled condition; second means for monitoring the controlled condition and providing a signal proportional to this controlled condition; third means for monitoring the limited condition and providing a signal proportional to this limited condition; controller means having a set point input, a measure input, and a control signal output, said controller means holding the control signal at its output constant when the signals at its inputs are equal and responding to signals at its inputs which are unequal to change the control signal at its output to adjust the controlled process condition until the signals at its inputs are restored to equal amplitude; means for controlling said controlled process condition including means responsive to said control signal from the controller output, said controlling means changing said controlled condition as said control signal changes; means for transmitting the signal from the first monitoring means to the set point input of the controller means and for transmitting the signal from the second monitoring means to the measure input of the controller means; and override means having a nonoperable state and an operable state where the override means terminates transmission of the first monitoring signal to the controller set point input and transmits to said controller set point input the signal from the third monitoring means, said override means including means for comparing the signals from the third monitoring means with at least one of the signals from one of the other monitoring means and, when a predetermined relationship exists between compared signals indicating corrective action should be taken to maintain said limited condition within said predetermined limits, for switching the override means to the operable state.

Claim 40

Dependent Claim 45 words

The control apparatus of claim 31 where the transmitting means includes means calibrated to maintain the limited condition withiN said predetermined limits, and calibration means for said calibrated means which calibrates said calibrated means whenever the override means transmits the signal to the controller means.

Claim 41

Dependent Claim 220 words

For use with a process where liquid flows into and from containing means, and the liquid level in the containing means deviates from a predetermined point between predetermined upper and lower limits, control apparatus including means for monitoring the influent flow rate at which liquid flows into the containing means and for generating a control signal proportional to said flow rate; means for monitoring the liquid level and for generating a level signal proportional to the liquid level; controller means responsive to the control signal and the level signal for controlling the effluent flow rate at which liquid flows from the containing means, said controller means on receiving the control signal changing the effluent flow rate as the control signal changes, and on receiving the level signal changing the effluent flow rate as the level signal changes; signal transmission means for the level and control signals, said transmission means having a high select mode of operation when liquid level is above said predetermined point and a low select mode of operation when the liquidu level is below said predetermined point, said transmission means in the high select mode transmitting to the controller means whichever of the signals has the highest amplitude and in the low select mode transmitting to the controller means whichever of the signals has the lowest amplitude.

Claim 42

Dependent Claim 220 words

For use with a process where liquid flows into and from containing means, and the liquid level in the containing means deviates from a predetermined point between predetermined upper and lower limits, control apparatus including means for monitoring the influent flow rate at which liquid flows into the containing means and for generating a control signal proportional to said flow rate; means for monitoring the liquid level and for generating a level signal proportional to the liquid level; controller means responsive to the control signal and the level signal for controlling the effluent flow rate at which liquid flows from the containing means, said controller means on receiving the control signal changing the effluent flow rate as the control signal changes, and on receiving the level signal changing the effluent flow rate as the level signal changes; signal transmission means for the level and control signals, said transmission means having a high select mode of operation when liquid level is above said predetermined point and a low select mode of operation when the liquidu level is below said predetermined point, said transmission means in the high select mode transmitting to the controller means whichever of the signals has the highest amplitude and in the low select mode transmitting to the controller means whichever of the signals has the lowest amplitude.

Claim 43

Dependent Claim 58 words

The control apparatus of claim 33 where in the transmission means including means calibrated to maintain the flow of liquid from the containing means such that said liquid level is within said predetermined limits, and calibration means for said calibrated means which calibrates said calibrated means whenever the transmission means transmits the level signal to the controller means.

Claim 44

Dependent Claim 445 words

For use with a process having at least three variable and interrelated conditions, apparatus operable in either a manual mode or an automatic mode of operation for controlling at least one of said process conditions, comprising multiplier means having first and second inputs and an output transmitting a signal that is a function of the signals received at the multiplier''s inputs, said first multiplier input receiving a signal proportional to an uncontrolled process condition; first controller means having a set point input connected to the multiplier output, a measure input which receives a signal proportional to the control process condition, and a control signal output, said first controller means responding to the signals at its inputs having unequal amplitudes to change the control signal at its output until the signal at its inputs are of equal amplitude; second controller means having a set point input, a measure input which receives a signal proportional to an uncontrolled process condition other than the uncontrolled process condition signal received by the first controller means, and a control signal output, second controller means responding to the signals at its inputs having unequal amplitude to change the control signal at its output until the signals at its inputs are of equal amplitude; comparator means having first and second inputs and an output, said first input receiving a signal proportional to said control process condition and said second input receiving a signal from multiplier output, said comparator output signal during manual mode remaining constant so long as the signal at the comparator inputs are equal and, when said input signals are unequal, said output signal increasing or decreasing in proportion to the difference between input signals; means for connecting the second controller output to the second multiplier input when the apparatus is in the automatic mode and for disconnecting said controller output and said second multiplier input when the apparatUs is in the manual mode; means for connecting the comparator output to the second multiplier input when the apparatus is in the manual mode, and for disconnecting said comparator output and said second multiplier input when the apparatus is in the automatic mode; means for following the signal from the comparator output during the manual mode, and, on switching from the manual mode to the automatic mode, for regulating the output signal from the second controller means so that said output signal initially equal the comparator output signal immediately preceding switching from the manual to the automatic mode; and means for switching the apparatus between automatic and manual mode of operation, said switching means including means for regulating the first controller means output signal manually during said manual mode of operation.

Claim 45

Dependent Claim 445 words

For use with a process having at least three variable and interrelated conditions, apparatus operable in either a manual mode or an automatic mode of operation for controlling at least one of said process conditions, comprising multiplier means having first and second inputs and an output transmitting a signal that is a function of the signals received at the multiplier''s inputs, said first multiplier input receiving a signal proportional to an uncontrolled process condition; first controller means having a set point input connected to the multiplier output, a measure input which receives a signal proportional to the control process condition, and a control signal output, said first controller means responding to the signals at its inputs having unequal amplitudes to change the control signal at its output until the signal at its inputs are of equal amplitude; second controller means having a set point input, a measure input which receives a signal proportional to an uncontrolled process condition other than the uncontrolled process condition signal received by the first controller means, and a control signal output, second controller means responding to the signals at its inputs having unequal amplitude to change the control signal at its output until the signals at its inputs are of equal amplitude; comparator means having first and second inputs and an output, said first input receiving a signal proportional to said control process condition and said second input receiving a signal from multiplier output, said comparator output signal during manual mode remaining constant so long as the signal at the comparator inputs are equal and, when said input signals are unequal, said output signal increasing or decreasing in proportion to the difference between input signals; means for connecting the second controller output to the second multiplier input when the apparatus is in the automatic mode and for disconnecting said controller output and said second multiplier input when the apparatUs is in the manual mode; means for connecting the comparator output to the second multiplier input when the apparatus is in the manual mode, and for disconnecting said comparator output and said second multiplier input when the apparatus is in the automatic mode; means for following the signal from the comparator output during the manual mode, and, on switching from the manual mode to the automatic mode, for regulating the output signal from the second controller means so that said output signal initially equal the comparator output signal immediately preceding switching from the manual to the automatic mode; and means for switching the apparatus between automatic and manual mode of operation, said switching means including means for regulating the first controller means output signal manually during said manual mode of operation.

Claim 46

Independent Claim 89 words

A method for controlling the operation of a fractionation tower comprising a. monitoring changes in feed composition and feed flow rate, b. withdrawing distillate and bottoms from the tower at rates in accordance with changes in the feed composition and feed flow rate, c. maintaining the tower pressure essentially constant by controlling heat flow to the tower in accordance with changes in the feed composition and feed flow rate, and d. permitting the liquid level in the bottom of the tower to fluctuate within predetermined upper and lower limits.

Claim 47

Independent Claim 89 words

A method for controlling the operation of a fractionation tower comprising a. monitoring changes in feed composition and feed flow rate, b. withdrawing distillate and bottoms from the tower at rates in accordance with changes in the feed composition and feed flow rate, c. maintaining the tower pressure essentially constant by controlling heat flow to the tower in accordance with changes in the feed composition and feed flow rate, and d. permitting the liquid level in the bottom of the tower to fluctuate within predetermined upper and lower limits.

Annuity Stage	Window Opens	Payment Deadline	Surcharge Period Until	Estimated Fee	Status
3.5 Years (Year 4)	1978-09-15	1979-03-17	1979-09-16	$2000.00	Window Closed / Lapsed
7.5 Years (Year 8)	1982-09-15	1983-03-17	1983-09-16	$3760.00	Window Closed / Lapsed
11.5 Years (Year 12)	1986-09-15	1987-03-17	1987-09-16	$7700.00	Window Closed / Lapsed

Control apparatus for fractionation tower

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