US5066402A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method of changing operating modes in automatic water filtering apparatus using tubular membranes
Assignee: Lyonnaise des Eaux Dumez SA
•
Filing: 1990-10-31
•
Granted: 1991-11-19
•
Expires: 2010-10-31
Abstract
Abstract A method of changing operating modes in automatic water filtering apparatus comprising inside-skin tubular membrane modules for filtering water, the possible filtering modes being: dead-end filtering; cross-flow filtering; and cross-flow filtering with continuous purging; both cross-flow filtering modes including recirculation in a loop; wherein two types of triggering are provided for filter membrane backwashes, a first one of said types being related to time periods between two backwashes, which time periods are predetermined for each mode of filtering, and a second one of said types being related to reference values of an operating parameter of the automatic apparatus, which values are predetermined for each mode of filtering; with the mode of filtering being changed after a backwash has been triggered in response to one of the reference values, with changes taking place in the following order: dead-end filtering, cross-flow filtering, cross-flow filtering with continuous purging, or vice versa.
Inventors
- 👤 Christophe Anselme
- 👤 Loic Daniel
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 07:42
CPC Classifications
B; B01; B01D; B01D61/00; B01D61/14; B01D61/22; B01D65/00; B01D65/02; B01D2321/00; B01D2321/04
Claims Analysis
Total Claims: 6
Claim 1
Independent Claim
152 words
A method of changing operating modes in automatic water filtering apparatus comprising inside-skin tubular membrane modules for filtering water, the possible filtering modes being: dead-end filtering, cross-flow filtering, and cross-flow filtering with continuous purging, both cross-flow filtering modes including recirculation in a loop; comprising the stages of (A) providing two types of triggering for filter membrane backwashes, a first one of said types being related to time periods between two backwashes, which time periods are predetermined for each mode of filtering, and a second one of said types being related to reference values of an operating parameter of the automatic apparatus, which reference values are predetermined for each mode of filtering; and (B) changing the mode of filtering after a backwash has been triggered in response to one of said reference values, with changes taking place in the following order: dead-end filtering, cross-flow filtering, cross-flow filtering with continuous purging, or vice versa.
Claim 2
Independent Claim
152 words
A method of changing operating modes in automatic water filtering apparatus comprising inside-skin tubular membrane modules for filtering water, the possible filtering modes being: dead-end filtering, cross-flow filtering, and cross-flow filtering with continuous purging, both cross-flow filtering modes including recirculation in a loop; comprising the stages of (A) providing two types of triggering for filter membrane backwashes, a first one of said types being related to time periods between two backwashes, which time periods are predetermined for each mode of filtering, and a second one of said types being related to reference values of an operating parameter of the automatic apparatus, which reference values are predetermined for each mode of filtering; and (B) changing the mode of filtering after a backwash has been triggered in response to one of said reference values, with changes taking place in the following order: dead-end filtering, cross-flow filtering, cross-flow filtering with continuous purging, or vice versa.
Claim 3
Dependent Claim
101 words
A method according to claim 1, wherein switching from dead-end filtering mode to cross-flow filtering mode is performed by activating the loop to recirculate non-filtered water to the filter membranes after a backwash has been triggered at least once by reaching a first one of said reference values, and wherein switching to cross-flow filtering mode with continuous purging is performed by opening a valve for purging a part of the non-filtered water circulating in the loop after the time interval between two backwashes triggered by reaching a second one of said reference values has become less than a predetermined time period.
Claim 4
Dependent Claim
74 words
A method according to claim 2, wherein switching from cross-flow filtering mode with purging to cross-flow filtering mode without purging takes place when n consecutive backwashes have been triggered by reaching the end of the time period predetermined for cross-flow filtering, and switching from cross-flow filtering mode to dead-end filtering mode takes place when m consecutive backwashes have been triggered by reaching the end of the time period predetermined for cross-flow filtering, with m>n.
Claim 5
Dependent Claim
38 words
A method according to claim 1, wherein inlet pressures to the modules are used as said reference values, said inlet pressures corresponding respectively to maximum transmembrane pressure in dead-end filtering and to maximum transmembrane pressure in cross-flow filtering.
Claim 6
Dependent Claim
37 words
A method according to claim 1, wherein, upon stopping the operation of the modules, a backwashing is performed and, upon restarting the operation of the modules, the dead-end filtering mode is selected as the initial filtering mode.
References Cited (Backward Citations)
JPS5458944A
Cited
US4482461A
Cited
US4657040A
Cited
US4921610A
Cited
US4844804A
Cited
WO1989011899A1
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1994-11-18 | 1995-05-20 | 1995-11-19 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1998-11-18 | 1999-05-20 | 1999-11-19 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2002-11-18 | 2003-05-20 | 2003-11-19 | $7700.00 | Window Closed / Lapsed |