Patent US4438499A successfully refreshed from Google Patents.
US4438499A
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Fractional distillation process control
Assignee: Applied Automation Inc
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Filing: 1981-10-01
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Granted: 1984-03-20
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Expires: 2001-10-01
Abstract
Abstract In a fractional distillation process in which the designation of the primary product stream changes, the desired composition of the primary product stream and a secondary product stream are maintained without losing automatic control of the process for an extended period of time while the controllers controlling the process are retuned for the new operating conditions. Two sets of tuning constants are available to each controller and these tuning constants are automatically switched as required by the designation of the primary product stream.
Inventors
- 👤 Bruce A. Jensen
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-27 23:32
CPC Classifications
B; B01; B01D; B01D3/00; B01D3/42; B01D3/4211; B01D3/4227
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
326 words
A method for controlling a fractional distillation process comprising the steps of: establishing a first signal representative of the concentration of at least one component in a first product stream withdrawn from said fractional distillation process; establising a second signal representative of the desired concentration of said at least one component in said first product stream; applying said first signal and said second signal to a first controller means to thereby establish a third signal which is responsive to the difference between said first signal and said second signal; establishing a fourth signal representative of the concentration of at least one component in a second product stream withdrawn from said fractional distillation process; establishing a fifth signal representative of the desired concentration of said at least one component in said second product stream; supplying said fourth signal and said fifth signal to a second controller means to thereby establish a sixth signal responsive to the difference between said fourth signal and said fifth signal; establishing primary first tuning constants for said first controller means for use when said first controller means controlling a primary process variable; establishing secondary first tuning constants for said first controller means for use when said first controller means in controlling a secondary process variable; establishing primary second tuning constants for said second controller means for use when said second controller means is controlling said primary process variable; establishing secondary second tuning constants for said second controller means for use when said second controller means is controlling said secondary process variable; designating said first product stream as a primary product stream; supplying said primary first tuning constants to said first controller means; storing said secondary first tuning constants in memory; supplying said secondary second tuning constants to said second controller means; storing said primary second tuning constants in memory; manipulating said primary process variable in response to said third signal; and manipulating said secondary process variable in response to said sixth signal.
Claim 2
Independent Claim
326 words
A method for controlling a fractional distillation process comprising the steps of: establishing a first signal representative of the concentration of at least one component in a first product stream withdrawn from said fractional distillation process; establising a second signal representative of the desired concentration of said at least one component in said first product stream; applying said first signal and said second signal to a first controller means to thereby establish a third signal which is responsive to the difference between said first signal and said second signal; establishing a fourth signal representative of the concentration of at least one component in a second product stream withdrawn from said fractional distillation process; establishing a fifth signal representative of the desired concentration of said at least one component in said second product stream; supplying said fourth signal and said fifth signal to a second controller means to thereby establish a sixth signal responsive to the difference between said fourth signal and said fifth signal; establishing primary first tuning constants for said first controller means for use when said first controller means controlling a primary process variable; establishing secondary first tuning constants for said first controller means for use when said first controller means in controlling a secondary process variable; establishing primary second tuning constants for said second controller means for use when said second controller means is controlling said primary process variable; establishing secondary second tuning constants for said second controller means for use when said second controller means is controlling said secondary process variable; designating said first product stream as a primary product stream; supplying said primary first tuning constants to said first controller means; storing said secondary first tuning constants in memory; supplying said secondary second tuning constants to said second controller means; storing said primary second tuning constants in memory; manipulating said primary process variable in response to said third signal; and manipulating said secondary process variable in response to said sixth signal.
Claim 3
Dependent Claim
121 words
A method in accordance with claim 1 additionally comprising the steps of: changing the designation of the primary product stream from said first product stream in said second product stream; automatically supplying said secondary first tuning constants from memory to said first controller means and storing said primary first tuning constants in memory; automatically supplying said primary second tuning constants to said second controller means and storing said secondary second tuning constants in memory; automatically changing the manipulation of said primary process variable in response to said third signal to manipulation in response to said sixth signal; and automatically changing the manipulation of said secondary process variable in response to said sixth signal to manipulation in response to said third signal.
Claim 4
Dependent Claim
176 words
A method in accordance with claim 1 wherein said first product stream is an overhead product stream, wherein said second product stream is a bottoms product stream, wherein said primary process variable in the rate at which heat is supplied to said fractional distillation process, wherein said secondary process variable is the flow rate of the external reflux to said fractional distillation process, wherein said third signal is representative of the desired rate at which heat should be supplied to said fractional distillation process in order to maintain a desired overhead product stream composition and wherein said step of manipulating said primary process variable in response to said third signal comprises: establishing a seventh signal representative of the actual rate at which heat is being supplied to said fractional distillation process; comparing said third signal and said seventh signal and establishing an eighth signal responsive to the difference between said third signal and said seventh signal; and manipulating the rate at which heat is supplied to said fractional distillation process in response to said eighth signal.
Claim 5
Dependent Claim
100 words
A method in accordance with claim 3 wherein said sixth signal is representative of the flow rate of said external reflux required to maintain a desired bottoms product composition and wherein said step of manipulating said secondary process variable in response to said sixth signal comprises; establishing a ninth signal representative of the actual flow rate of said external reflux; comparing said sixth signal and said ninth signal and extablishing a tenth signal responsive to the difference between said sixth signal and said ninth signal; and manipulating the flow rate of said external reflux in response to said tenth signal.
Claim 6
Dependent Claim
175 words
A method in accordance with claim 2 wherein said first product stream is an overhead product stream, wherein said second product stream is a bottom product stream, wherein said primary process variable is the rate at which heat is supplied to said fractional distillation process, wherein said secondary process variable is the flow rate of the external reflux to said fractional distillation process, wherein said sixth signal is representative of the desired rate at which heat should be supplied to said fractional distillation process in order to maintain a desired bottoms product composition and wherein said step of manipulating said primary process variable in response to said sixth signal comprises; establishing a seventh signal representative of the actual rate at which heat is being supplied to said fractional distillation process; comparing said sixth signal and said seventh signal and establishing an eighth signal responsive to the difference between said sixth signal and said seventh signal; and manipulating the rate at which heat is supplied to said fractional distillation process in response to said eighth signal.
Claim 7
Dependent Claim
100 words
A method in accordance with claim 5 wherein said third signal is representative of the flow rate of said external reflux required to maintain a desired overhead product composition and wherein said step of manipulating said secondary process variable in response to said third signal comprises: establishing a ninth signal representative of the actual flow rate of said external reflux; comparing said third signal and said ninth signal and establishing a tenth signal responsive to the difference between said third signal and said ninth signal; and manipulating the flow rate of said external reflux in response to said tenth signal.
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) | 1987-03-20 | 1987-09-19 | 1988-03-20 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1991-03-20 | 1991-09-19 | 1992-03-20 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1995-03-20 | 1995-09-19 | 1996-03-20 | $7700.00 | Window Closed / Lapsed |