US3668063A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Removal of entrained air from cellulose pulp before bleaching of the pulp
Assignee: Valmet AB
•
Filing: 1971-04-01
•
Granted: 1972-06-06
•
Expires: 1991-04-01
Abstract
Abstract Preliminary to being delivered by a ''''thick stock pump'''' means to a generally vertical bleaching vessel there is added to a cellulose pulp a fluid, such as steam, oxygen or a gaseous bleaching agent to flow countercurrent to the pulp in such manner that any air in the pulp is displaced and is replaced by bleaching agent before bleaching of the pulp in the bleaching vessel.
Inventors
- 👤 Hans-Erik Engstrom
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-26 18:45
CPC Classifications
D; D21; D21C; D21C9/00; D21C9/10; D21C9/1005
Claims Analysis
Total Claims: 4
Claim 1
Independent Claim
13 words
In a method as claimed in claim 1 wherein the fluid is steam.
Claim 2
Dependent Claim
13 words
In a method as claimed in claim 1, wherein the fluid is oxygen.
Claim 3
Dependent Claim
48 words
In a method as claimed in claim 1 the further step comprising detecting the amount of fluid in the pulp at a point upstream from the point of introduction of said fluid and controlling the amount of fluid so introduced dependent on the value of the amount detected.
Claim 4
Dependent Claim
34 words
In a method as claimed in claim 1 wherein the gaseous bleaching agent introduced into the tower is introduced into the space at the top of the tower above the column of pulp therein.
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) | 1975-06-06 | 1975-12-06 | 1976-06-06 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1979-06-06 | 1979-12-06 | 1980-06-06 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1983-06-06 | 1983-12-06 | 1984-06-06 | $7700.00 | Window Closed / Lapsed |