US3568939A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method and apparatus for controlling pulp refiners
Assignee: Westvaco Corp
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Filing: 1968-10-03
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Granted: 1971-03-09
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Expires: 1988-10-03
Abstract
Abstract A control system, receiving inputs from a group of grinders or refiners, generates a signal representative of overall grinding or refining action. Operating from this signal, the control system controls at least one of the grinders or refiners in the group such that the cumulative qualitative output from all the grinders or refiners is equal to a desired set point.
Inventors
- 👤 Donald B Brewster
- 👤 Robert C Hatcher
- 👤 Cheng S Lin
- 👤 Philip H Emery Jr
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-28 19:00
CPC Classifications
D; D21; D21B; D21B1/00; D21B1/04; D21B1/06; D21B1/063
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
196 words
A control system for controlling the quality of the output stock of a group of pulp refiners operating in parallel which comprises: a. means for obtaining a plurality of signals, each representative of the refining action of each refiner in said group; b. means for combining said plurality of signals to obtain a first signal represeNtative of the mean refining action of all of said refiners; c. means for generating a second signal representative of desired mean refining action; d. means for comparing said first signal with said second signal to develop an error signal; e. means for calculating a group control signal in response to said error signal; f. means for generating at least one group control signal allocation factor; g. means for generating at least one individual control signal by operating on said group control signal in response to said allocation factor; h. means for altering at least one individual refining action set point in response to said individual control signal; and i. means for controlling the refining action of at least one individual refiner in said group in response to the deviation of actual refining action from said individual refining action set point.
Claim 2
Dependent Claim
192 words
A control system for controlling the quality of the output stock of a group of pulp refiners operating in parallel which comprises: a. means for obtaining a plurality of signals, each representative of the temperature difference across each refiner in said group; b. means for combining said plurality to obtain a first signal representative of the mean temperature difference across all of said refiners; c. means for generating a second signal representative of desired mean temperature difference; d. means for comparing said first signal with said second signal to develop an error signal; e. means for calculating a group control signal in response to said error signal; f. means for generating at least one group control signal allocation factor; g. means for generating at least one individual control signal by operating on said group control signal in response to said allocation factor; h. means for altering at least one individual temperature difference set point in response to said individual control signal; and i. means for controlling the temperature difference across at least one individual refiner in response to the deviation of the individual temperature difference from said individual temperature difference set point.
Claim 3
Dependent Claim
218 words
A control system for controlling the quality of the output stock of a group of pulp refiners operating in parallel which comprises: a. means for obtaining a first plurality of signals, each representative of the temperature difference across each refiner in said group; b. means for obtaining a second plurality of signals, each representative of the flow through each refiner in said group; c. means for combining said first plurality and said second plurality of signals to obtain a third signal representative of the flow weighted average temperature difference across all of the refiners in said group; d. means for generating a set point signal; e. means for comparing said third signal with said set point signal to develop an error signal; f. means for calculating a group control signal in response to said error signal; g. means for generating group control signal allocation factors; h. means for generating at least one individual control signal by operating on said group control signal in response to said allocation factors; i. means for altering at least one individual temperature difference set point in response to said individual control signals; and j. means for controlling the temperature difference across at least one individual refiner in response to the deviation of the individual temperature differences from said individual temperature difference set point.
Claim 4
Dependent Claim
14 words
The control system of claim 4 wherein all of said allocation factors are equal.
Claim 5
Dependent Claim
51 words
The control system of claim 5 wherein said allocation factor equals the ratio of the total flow of stock through all the refiners in the group to the total flow of stock through all the refiners which are in the group and are controlled in response to the group control signal.
Claim 6
Independent Claim
193 words
The method of controlling a group of pulp refiners operating in parallel which comprises: a. obtaining from each refiner in said group of refiners at least one signal which is representative of the refining station of each of said refiners; b. combining each of said signals from each of said refiners into a first signal representative of overall refining action; c. obtaining a second signal representative of desired overall refining action; d. comparing said first and second signals to obtain an error signal; e. producing a group control signal in response to said error signal; f. obtaining at least one group control signal allocation factor; g. generating at least one individual refining action set point signal from said group control signal in response to said allocation factor; h. comparing said individual refining action set point signal to a signal representing the actual refining action of at least one of said refiners to obtain a second error signal; and i. controlling at least one of said refiners in response to said second error signal whereby the overall refining of all of said refiners in the group is equal to the desired overall refining action.
Claim 7
Dependent Claim
164 words
A control system for controlling the quality of the output stock of a group of pulp refiners operating in parallel comprising: a. means for obtaining from each of said refiners at least one signal representative of the refining action of each refiner in said group; b. means for obtaining from each of said refiners at least one signal representative of the flow of stock through each refiner in said group; c. means for combining said signals representative of the refining action of each of said refiners and said signals representative of the flow of stock through each of said refiners into a first signal representative of the mean refining action of all of said refiners; d. means for generating a set point signal representative of the desired mean refining action; e. means for comparing said first signal with said set point signal to develop an error signal; and f. means for controlling at least one of said refiners in response to said error signal.
Claim 8
Dependent Claim
30 words
The apparatus of claim 8 wherein said signal representative of the refining action of each refiner in said group is representative of the power consumption of the refiner drive motor.
Claim 9
Dependent Claim
33 words
The apparatus of claim 8 wherein said signal representative of the refining action of each refiner in said group is representative of the temperature difference across each of the refiners in the group.
Claim 10
Dependent Claim
22 words
The apparatus of claim 10 wherein said means for controlling includes means for varying the loading on one of the refining surfaces.
Claim 11
Dependent Claim
20 words
The apparatus of claim 10 wherein said means for controlling includes means for varying the spacing between the refining surfaces.
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) | 1974-03-08 | 1974-09-07 | 1975-03-09 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1978-03-08 | 1978-09-07 | 1979-03-09 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1982-03-08 | 1982-09-07 | 1983-03-09 | $7700.00 | Window Closed / Lapsed |