US3754417A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Oxygen bleaching
Assignee: PPG Architectural Coatings Canada Inc
•
Filing: 1970-12-10
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Granted: 1973-08-28
•
Expires: 1990-12-10
Abstract
Abstract An apparatus for treating lignocellulosic material such as wood pulp with oxygen under pressure as a step in an oxygen bleaching process. The apparatus introduces the lignocellulosic material, oxygen and other reagents into the pressurized vessel continuously, and continuously withdraws the treated product and spent reagents. The apparatus permits the carrying out of a continuous oxygen bleaching process.
Inventors
- 👤 A Jamieson
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-07 23:49
CPC Classifications
D; D21; D21C; D21C9/00; D21C9/10
Claims Analysis
Total Claims: 28
Claim 1
Independent Claim
151 words
An apparatus for the continuous treatment of lignocellulosic material with oxygen or an oxygen-containing gas which comprises 1. a reaction vessel adapted to operate under supra atmospheric pressure, 2. means for supplying oxygen or an oxygen-containing gas to the vessel under supra atmospheric pressure, 3. means for introducing continuously aqueous lignocellulosic pulp into the pressurized reaction vessel, 4. means for supplying alkaline reagent to the reaction vessel, 5. means for heating the contents of the reaction vessel, 6. means for mixing the lignocellulosic pulp with the oxygen or oxygen-containing gas so as to renew continuously the interface between the lignocellulosic material of the pulp and the gas, 7. means for controlling the level of the aqueous lignocellulosic pulp in the reaction vessel thus controlling the residence time of the lignocellulosic pulp in the vessel, and 8. means for withdrawing continuously oxygen treated aqueous alkaline lignocellulosic pulp from the pressurized reaction vessel.
Claim 2
Independent Claim
151 words
An apparatus for the continuous treatment of lignocellulosic material with oxygen or an oxygen-containing gas which comprises 1. a reaction vessel adapted to operate under supra atmospheric pressure, 2. means for supplying oxygen or an oxygen-containing gas to the vessel under supra atmospheric pressure, 3. means for introducing continuously aqueous lignocellulosic pulp into the pressurized reaction vessel, 4. means for supplying alkaline reagent to the reaction vessel, 5. means for heating the contents of the reaction vessel, 6. means for mixing the lignocellulosic pulp with the oxygen or oxygen-containing gas so as to renew continuously the interface between the lignocellulosic material of the pulp and the gas, 7. means for controlling the level of the aqueous lignocellulosic pulp in the reaction vessel thus controlling the residence time of the lignocellulosic pulp in the vessel, and 8. means for withdrawing continuously oxygen treated aqueous alkaline lignocellulosic pulp from the pressurized reaction vessel.
Claim 3
Dependent Claim
15 words
means for supplying oxygen or an oxygen-containing gas to the vessel under supra atmospheric pressure,
Claim 4
Dependent Claim
15 words
means for supplying oxygen or an oxygen-containing gas to the vessel under supra atmospheric pressure,
Claim 5
Dependent Claim
22 words
An apparatus as claimed in claim 1 wherein the reaction vessel is a multi-compartment vessel provided with mechanical agitators in each compartment.
Claim 6
Dependent Claim
54 words
An apparatus as claimed in claim 1 wherein the reaction vessel is a single compartment vessel provided with a gas dispersing grid located at the bottom of the vessel, said grid being supplied by gas from the means for supplying oxygen or oxygen-containing gas, said grid serving to mix the contents of the vessel.
Claim 7
Dependent Claim
12 words
means for introducing continuously aqueous lignocellulosic pulp into the pressurized reaction vessel,
Claim 8
Dependent Claim
12 words
means for introducing continuously aqueous lignocellulosic pulp into the pressurized reaction vessel,
Claim 9
Dependent Claim
9 words
means for supplying alkaline reagent to the reaction vessel,
Claim 10
Dependent Claim
9 words
means for supplying alkaline reagent to the reaction vessel,
Claim 11
Dependent Claim
24 words
An apparatus as claimed in claim 3 wherein there is provided means for controlling the partial pressure of the oxygen in the reaction vessel.
Claim 12
Dependent Claim
22 words
An apparatus as claimed in claim 3 wherein the means for introducing pulp into the reaction vessel is a rotary pocket valve.
Claim 13
Dependent Claim
9 words
means for heating the contents of the reaction vessel,
Claim 14
Dependent Claim
9 words
means for heating the contents of the reaction vessel,
Claim 15
Dependent Claim
29 words
means for mixing the lignocellulosic pulp with the oxygen or oxygen-containing gas so as to renew continuously the interface between the lignocellulosic material of the pulp and the gas,
Claim 16
Dependent Claim
29 words
means for mixing the lignocellulosic pulp with the oxygen or oxygen-containing gas so as to renew continuously the interface between the lignocellulosic material of the pulp and the gas,
Claim 17
Dependent Claim
22 words
An apparatus as claimed in claim 3 wherein the means for withdrawing pulp from the reaction vessel is a rotary pocket valve.
Claim 18
Dependent Claim
27 words
An apparatus as claimed in claim 3 wherein the means for heating the contents of the reaction vessel is a source of steam feeding into the vessel.
Claim 19
Dependent Claim
27 words
means for controlling the level of the aqueous lignocellulosic pulp in the reaction vessel thus controlling the residence time of the lignocellulosic pulp in the vessel, and
Claim 20
Dependent Claim
27 words
means for controlling the level of the aqueous lignocellulosic pulp in the reaction vessel thus controlling the residence time of the lignocellulosic pulp in the vessel, and
Claim 21
Dependent Claim
15 words
means for withdrawing continuously oxygen treated aqueous alkaline lignocellulosic pulp from the pressurized reaction vessel.
Claim 22
Dependent Claim
15 words
means for withdrawing continuously oxygen treated aqueous alkaline lignocellulosic pulp from the pressurized reaction vessel.
Claim 23
Dependent Claim
21 words
An apparatus as claimed in claim 3 wherein there is provided means for recirculating the oxygen-containing gas through the pulp suspension.
Claim 24
Dependent Claim
36 words
An apparatus as claimed in claim 3 wherein there are provided means for separating alkaline aqueous liquor from the lignocellulosic pulp withdrawn from the reaction vessel, and means for recirculating this liquor to the reaction vessel.
Claim 25
Dependent Claim
24 words
An apparatus as claimed in claim 1 wherein the reaction vessel is a multi-compartment vessel having a plurality of perforated plate air dispersing members.
Claim 26
Dependent Claim
21 words
An apparatus as claimed in claim 1 Wherein the reaction vessel is a multi-compartment vessel having draft tube air dispersing members.
Claim 27
Dependent Claim
15 words
An apparatus as claimed in claim 1 wherein the reaction vessel is toroidal in shape.
Claim 28
Dependent Claim
27 words
An apparatus as claimed in claim 1 wherein the reaction vessel is a single compartment tubular vessel provided with means for mechanical mixing of the vessel contents.
References Cited (Backward Citations)
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US2730888A
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US3130076A
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US3134384A
Cited
US3575795A
Cited
US3587257A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1976-08-27 | 1977-02-26 | 1977-08-28 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-08-27 | 1981-02-26 | 1981-08-28 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-08-27 | 1985-02-26 | 1985-08-28 | $7700.00 | Window Closed / Lapsed |