US4239493A
Expired / Lapsed
US
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Method and apparatus for controlling the pH
Assignee: Individual
•
Filing: 1978-06-07
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Granted: 1980-12-16
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Expires: 1998-06-07
Abstract
Abstract The invention relates to a method and apparatus for controlling the pH in a continuous flow vessel into which process material is fed through a feed channel and controlling chemical solution is fed through a control channel and in which the pH is measured at an output part of the vessel in order to effect the control by controlling the control chemical feed according to the feedback method, the value of a reference variable being given by a pH number. According to the invention the result of the pH measurement as well as the reference value are transformed to the hydrogen ion concentration or to another concentration quantity unambiguously depending on said hydrogen ion concentration, a final feedback quantity is determined by means of an equation describing dissociation equilibria in the solution, said feedback quantity being a function of the concentration quantity derived from the pH measurement and eventually a function of an independent concentration quantity derived from an other measurement at the vessel output, a final reference value is determined by means of said equation, said final reference value being a function of the concentration quantity derived from the initial reference value, and, eventually, a function of the independent concentration quantity mentioned, a control deviation is formed as the difference between said final reference value and said final feedback quantity, and, finally the feed of the controlling chemical is controlled on the basis of said control deviation, typically using a linear controller and an actuator controlled thereby.
Inventors
- 👤 Antti J. Niemi
- 👤 Pentti K. Jutila
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-29 03:58
CPC Classifications
B; B01; B01J; B01J19/00; B01J19/0086; B01J4/00; B01J4/02; G; G05; G05D; G05D21/00; G05D21/02; Y; Y10; Y10T; Y10T436/00; Y10T436/12
Claims Analysis
Total Claims: 9
Claim 1
Independent Claim
214 words
In a method for controlling pH in a continuous flow vessel which is entered by a process material through a feed channel and by controlling chemical solution through a control channel and in which the pH is measured at the output part of the vessel in order to effect the control by controlling the feed of the control chemical by the feedback method, the value of a reference variable being given and expressed by a pH number, a combination of steps which comprises: (a) transforming the result of the pH measurement to the hydrogen ion concentration, (b) transforming likewise the reference value given as a pH number to the corresponding hydrogen ion concentration, (c) determining, by means of an equation describing dissociation equilibria in the solution, a final feedback quantity which is a function of the concentration quantity in step (a), (d) determining, by means of said equation, a final reference value which is a function of the concentration quantity in step (b), (e) forming a control deviation as the difference of the final reference value in step (d) and of the final feedback quantity in step (c), and (f) controlling the feed of the controlling chemical on the basis of said control deviation, typically using a linear controller and an actuator controlled thereby.
Claim 2
Dependent Claim
214 words
In a method for controlling pH in a continuous flow vessel which is entered by a process material through a feed channel and by controlling chemical solution through a control channel and in which the pH is measured at the output part of the vessel in order to effect the control by controlling the feed of the control chemical by the feedback method, the value of a reference variable being given and expressed by a pH number, a combination of steps which comprises: (a) transforming the result of the pH measurement to the hydrogen ion concentration, (b) transforming likewise the reference value given as a pH number to the corresponding hydrogen ion concentration, (c) determining, by means of an equation describing dissociation equilibria in the solution, a final feedback quantity which is a function of the concentration quantity in step (a), (d) determining, by means of said equation, a final reference value which is a function of the concentration quantity in step (b), (e) forming a control deviation as the difference of the final reference value in step (d) and of the final feedback quantity in step (c), and (f) controlling the feed of the controlling chemical on the basis of said control deviation, typically using a linear controller and an actuator controlled thereby.
Claim 3
Dependent Claim
56 words
A method according to claim 1, wherein the final feedback quantity of step (c) and the final reference value of step (d), which are functions of the hydrogen ion concentration of step (a) and step (b), respectively, are also functions of an independent concentration quantity based on other measurement at the output end of the vessel.
Claim 4
Dependent Claim
186 words
In a method for controlling pH in a continuous flow vessel which is entered by a process material through a feed channel and by controlling chemical solution through a control channel and in which the pH is measured at the output part of the vessel in order to effect the control by controlling the feed of the control chemical by the feedback method, the value of a reference variable being given and expressed by a pH number, a combination of steps which comprises: (a) forming a final feedback quantity by transforming the result of the pH measurement to the difference between the hydrogen ion concentration and hydroxyl ion concentration, (b) transforming likewise the reference value given as a pH number to the difference between the corresponding hydrogen ion concentration and the hydroxyl ion concentration, (c) forming a control deviation as the difference of the transformed reference value in step (b) and of the transformed final feedback quantity in step (a) and (d) controlling the feed of the controlling chemical on the basis of said control deviation, typically using a linear controller and an actuator controlled thereby.
Claim 5
Dependent Claim
186 words
In a method for controlling pH in a continuous flow vessel which is entered by a process material through a feed channel and by controlling chemical solution through a control channel and in which the pH is measured at the output part of the vessel in order to effect the control by controlling the feed of the control chemical by the feedback method, the value of a reference variable being given and expressed by a pH number, a combination of steps which comprises: (a) forming a final feedback quantity by transforming the result of the pH measurement to the difference between the hydrogen ion concentration and hydroxyl ion concentration, (b) transforming likewise the reference value given as a pH number to the difference between the corresponding hydrogen ion concentration and the hydroxyl ion concentration, (c) forming a control deviation as the difference of the transformed reference value in step (b) and of the transformed final feedback quantity in step (a) and (d) controlling the feed of the controlling chemical on the basis of said control deviation, typically using a linear controller and an actuator controlled thereby.
Claim 6
Dependent Claim
215 words
Apparatus for controlling pH in a continuous flow vessel which is entered by a process material through a feed channel and by controlling chemical solution through a control channel and wherein the pH is measured at the output part of the vessel in order to effect the control by controlling the feed of the control chemical by the feedback method, the value of a reference variable being given and expressed by a pH number, said apparatus comprising: means for transforming the result of the pH measurement to the hydrogen ion concentration in said vessel; means for transforming the reference value given as a pH number to the corresponding hydrogen ion concentration; means for determining, by means of an equation describing dissociation equilibria in the solution, a final feedback quantity which is a function of the concentration quantity transformed from said pH measurement; means for determining, by means of said equation, a final reference value which is a function of the concentration quantity transformed from said reference value; means for forming a controlled deviation as the difference of said final reference value and said final feedback quantity; and means for controlling the feed of the controlling chemical as a function of said control deviation, said last-mentioned means including a linear controller and an actuator controlled thereby.
Claim 7
Dependent Claim
215 words
Apparatus for controlling pH in a continuous flow vessel which is entered by a process material through a feed channel and by controlling chemical solution through a control channel and wherein the pH is measured at the output part of the vessel in order to effect the control by controlling the feed of the control chemical by the feedback method, the value of a reference variable being given and expressed by a pH number, said apparatus comprising: means for transforming the result of the pH measurement to the hydrogen ion concentration in said vessel; means for transforming the reference value given as a pH number to the corresponding hydrogen ion concentration; means for determining, by means of an equation describing dissociation equilibria in the solution, a final feedback quantity which is a function of the concentration quantity transformed from said pH measurement; means for determining, by means of said equation, a final reference value which is a function of the concentration quantity transformed from said reference value; means for forming a controlled deviation as the difference of said final reference value and said final feedback quantity; and means for controlling the feed of the controlling chemical as a function of said control deviation, said last-mentioned means including a linear controller and an actuator controlled thereby.
Claim 8
Dependent Claim
183 words
Apparatus for controlling the pH in a continuous flow vessel which is entered by a process material through a feed channel and by controlling chemical solution through a control channel and in which the pH is measured at the output part of the vessel in order to effect the control by controlling the feed of the control chemical by the feedback method, the value of a reference variable being given and expressed by a pH number, said apparatus comprising: means for forming a final feedback quantity by transforming the result of the pH measurement to the difference between the hydrogen ion concentration and hydroxyl ion concentration in said vessel; means for transforming the reference value given as a pH number to the difference between the corresponding hydrogen ion concentration and the hydroxyl ion concentration; means for forming a control deviation as to difference of said transformed reference value and said transformed final feedback quantity; and means for controlling the feed of the controlling chemical on the basis of said control deviation, said last-mentioned means including a linear controller and an actuator controlled thereby.
Claim 9
Dependent Claim
183 words
Apparatus for controlling the pH in a continuous flow vessel which is entered by a process material through a feed channel and by controlling chemical solution through a control channel and in which the pH is measured at the output part of the vessel in order to effect the control by controlling the feed of the control chemical by the feedback method, the value of a reference variable being given and expressed by a pH number, said apparatus comprising: means for forming a final feedback quantity by transforming the result of the pH measurement to the difference between the hydrogen ion concentration and hydroxyl ion concentration in said vessel; means for transforming the reference value given as a pH number to the difference between the corresponding hydrogen ion concentration and the hydroxyl ion concentration; means for forming a control deviation as to difference of said transformed reference value and said transformed final feedback quantity; and means for controlling the feed of the controlling chemical on the basis of said control deviation, said last-mentioned means including a linear controller and an actuator controlled thereby.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1983-12-16 | 1984-06-16 | 1984-12-16 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1987-12-16 | 1988-06-16 | 1988-12-16 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1991-12-16 | 1992-06-16 | 1992-12-16 | $7700.00 | Window Closed / Lapsed |