US3768270A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Air separation
Assignee: BOC Group Ltd
•
Filing: 1971-11-22
•
Granted: 1973-10-30
•
Expires: 1991-11-22
Abstract
Abstract Krypton and xenon are recovered from air by passing oxygen vapour into a rectification column to produce a krypton/xenon concentrate. The concentrate is kept substantially free from hydrocarbon impurities by withdrawing a small liquid oxygen fraction, containing most of the impurities, from the separation unit producing the oxygen. The rectification column has an upper section and a lower section, the ratio of the number of trays in the upper section to the number of trays in the lower section being in the range 6 to 12.
Inventors
- 👤 P Schuftan
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-04 17:56
CPC Classifications
F; F25; F25J; F25J3/00; F25J3/02; F25J3/04; F25J3/04406; F25J3/04412; F25J3/04248; F25J3/04333; F25J3/04363; F25J3/04642; F25J3/04745; F25J3/04751; F25J3/04757; F25J2200/00; F25J2200/34; F25J2200/40; F25J2200/76; F25J2205/00; F25J2205/60; F25J2205/82; F25J2220/00; F25J2220/52; F25J2235/00; F25J2235/50; F25J2250/00; F25J2250/30; F25J2250/50; Y; Y10; Y10S; Y10S62/00; Y10S62/923; Y10S62/925
Claims Analysis
Total Claims: 12
Claim 1
Independent Claim
22 words
A process as claimed in claim 1, wherein the reflux ratio in the upper section of the rectification column is about 0.1.
Claim 2
Dependent Claim
20 words
A process as claimed in claim 1, wherein the said ratio of the number of theoretical trays is about 9:1.
Claim 3
Dependent Claim
45 words
A process as claimed in claim 1, wherein the heat required for the reboilers is supplied by condensing oxygen, at least a part of the liquid thus obtained being introduced into the top of the upper section of the rectification column to act as reflux.
Claim 4
Dependent Claim
36 words
A process as claimed in claim 4, wherein the oxygen to be condensed is a part of the gaseous oxygen withdrawn from the top of the rectification column and compressed to the pressure required for condensation.
Claim 5
Dependent Claim
30 words
A process as claimed in claim 1, wherein the heat required for the reboilers is supplied by condensing air or nitrogen and the rectification column is provided with a condenser.
Claim 6
Dependent Claim
26 words
A process as claimed in claim 1, wherein residual oxygen in one or both of the weak and strong concentrates is removed by reaction with hydrogen.
Claim 7
Dependent Claim
50 words
A process as claimed in claim 7, wherein residual oxygen is removed in a water cooled burner and steam is admixed to both the strong concentrate and weak concentrate prior to introduction into the burner so as to reduce the oxygen concentration to the order of 15 to 20 percent.
Claim 8
Dependent Claim
25 words
A process as claimed in claim 1 wherein residual oxygen in one or both of the weak and strong concentrates is removed over a catalyst.
Claim 9
Dependent Claim
45 words
A process as claimed in claim 1, wherein oxygen and residual hydrocarbons are removed from the primary concentrates to yield a secondary concentrate that is then condensed and fractionally vaporised at about 1 bar, the vapour formed being passed at about 120*K through an adsorbent.
Claim 10
Dependent Claim
191 words
Air separation apparatus comprising an air separation column with a reboiler, an adsorber to remove the acetylene and the bulk of the other heavy hydrocarbons and of any carbon dioxide from a small liquid oxygen fraction withdrawn from the reboiler, a vaporiser to produce from the liquid leaving the adsorber a vapour fraction and a small volume of weak concentrate containing substantially all of any residual heavy hydrocarbons and carbon dioxide, a rectification column having a reboiler at the base and an upper and lower section operating at the same pressure with means providing a reflux ratio within the range of 0.07 to 0.2 and adapted to receive at a point near the base of the upper section the said vapour fraction in admixture with saturated oxygen vapour withdrawn from the reboiler of the air separation column and to produce for withdrawal from the base a strong primary concentrate substantially free from heavy hydrocarbons and for withdrawal fRom the top gaseous oxygen substantially free from krypton, the ratio of the number of trays in the upper section to the number in the lower section being within the range 6 to 12.
Claim 11
Dependent Claim
19 words
Apparatus as claimed in claim 11, wherein the said ratio of the number of theoretical trays is about 9.
Claim 12
Dependent Claim
15 words
Apparatus as claimed in claim 11 wherein the vaporiser contains at least one theoretical tray.
References Cited (Backward Citations)
US2096694A
Cited
US2040112A
Cited
US2433536A
Cited
US2497589A
Cited
US2962868A
Cited
US3191393A
Cited
US3596471A
Cited
US3609983A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1976-10-29 | 1977-04-30 | 1977-10-30 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-10-29 | 1981-04-30 | 1981-10-30 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-10-29 | 1985-04-30 | 1985-10-30 | $7700.00 | Window Closed / Lapsed |