US4048007A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method of removing solvent residues from aqueous paper pulps
Assignee: Dow Chemical Co
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Filing: 1976-07-09
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Granted: 1977-09-13
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Expires: 1996-07-09
Abstract
Abstract It has been found that solvent residues can be removed from aqueous paper pulps by stripping with economic volumes of gases. This can be done in conventional contacting equipment without reducing pulp consistencies below the levels typical of commercial paper-making operations. The solvents stripped out are recoverable and do not constitute a source of pollution.
Inventors
- 👤 J. Frank Valle-Riestra
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 12:08
CPC Classifications
D; D21; D21C; D21C5/00; D21C5/02; Y; Y02; Y02W; Y02W30/00; Y02W30/50; Y02W30/64
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
116 words
The method of removing residual amounts of volatile solvents from aqueous pulps of cellulosic fibers by gas stripping, wherein said pulp contains from about 0.4 to about 1.5 weight percent of said fibers comprising intimately contacting said pulp with n volumes of said gas under such conditions of agitation that the pulp consistency remains essentially uniform throughout, thereby removing at least a fraction of said solvent from said pulp, the ratio of n to the volumes of said gas required to remove the same fraction of solvent in the same manner, from the same volume of water containing the same initial amount of said solvent, being within the range of from about 1.5/l to about 6/l.
Claim 2
Independent Claim
116 words
The method of removing residual amounts of volatile solvents from aqueous pulps of cellulosic fibers by gas stripping, wherein said pulp contains from about 0.4 to about 1.5 weight percent of said fibers comprising intimately contacting said pulp with n volumes of said gas under such conditions of agitation that the pulp consistency remains essentially uniform throughout, thereby removing at least a fraction of said solvent from said pulp, the ratio of n to the volumes of said gas required to remove the same fraction of solvent in the same manner, from the same volume of water containing the same initial amount of said solvent, being within the range of from about 1.5/l to about 6/l.
Claim 3
Dependent Claim
72 words
The method of claim 1 in which: 1. the amount of said solvent in the pulp initially such that if the pulp is dewatered and then steam dried on rubber covered rolls, the rubber will be damaged to an intolerable extent, and 2. stripping is continued until the content of said solvent in the pulp has been reduced to a level such that said rubber will not be damaged to said extent.
Claim 4
Dependent Claim
16 words
The method of claim 1 wherein the solvent carried off in the stripping gas is recovered.
Claim 5
Dependent Claim
12 words
The method of claim 1 in which the stripping gas is air.
Claim 6
Dependent Claim
20 words
The method of claim 1 in which said contacting is carried out by spraying said pulp into said gas stream.
Claim 7
Dependent Claim
42 words
The method of claim 1 in which said contacting is carried out by passing said pulp and said gas in counter-current flow through a sieve tray column and the content of said fibers in the pulp is 1.0 weight percent or less.
Claim 8
Dependent Claim
27 words
The method of claim 1 in which the content of fibers in the pulp is within the range of from about 0.5 to about 0.75 weight percent.
Claim 9
Dependent Claim
19 words
The method of claim 4 in which the resulting solvent-laden air is employed to effect combustion of a fuel.
Claim 10
Dependent Claim
11 words
The method of claim 1 in which said solvent is perchloroethylene.
Claim 11
Dependent Claim
20 words
The method of claim 9 in which said residual amount of said solvent is 170 parts per million or less.
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) | 1980-09-12 | 1981-03-14 | 1981-09-13 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1984-09-12 | 1985-03-14 | 1985-09-13 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1988-09-12 | 1989-03-14 | 1989-09-13 | $7700.00 | Window Closed / Lapsed |