US3907971A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method of removing HF from gases
Assignee: GEA Group AG
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Filing: 1971-11-15
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Granted: 1975-09-23
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Expires: 1991-11-15
Abstract
Abstract Hydrogen fluoride is removed from a gas stream, e.g., the waste gas of an electrolysis cell for the production of aluminum, by using the gas as the fluidizing medium for an expanded fluid bed of particulate solids capable of taking up hydrogen fluoride. The solids content of the fluid bed chamber and the gas-flow parameters are adjusted to maintain a continuous solids concentration gradient throughout the entire vertically elongated chamber such that concentration decreases from the bottom to the top thereof. In addition, a major proportion of the solids removed from the chamber are withdrawn at the top of the bed in entrainment with gases, are separated from the effluent gas stream, and are returned to the chamber. The solids may be fed to the electrolysis bath.
Inventors
- 👤 Eberhard Dr Bohm
- 👤 Lothar Dr Reh
- 👤 Ernst Weckesser
- 👤 Gunter Dr Wilde
- 👤 Gunter Dr Winkhaus
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-22 18:20
CPC Classifications
B; B01; B01D; B01D53/00; B01D53/34; B01D53/46; B01D53/68; B01J; B01J8/00; B01J8/18
Claims Analysis
Total Claims: 3
Claim 1
Independent Claim
234 words
A PROCESS FOR REMOVING HYDROGEN FLUORIDE FROM A GAS STREAM BY TREATING THE GAS STREAM WITH A SOLID HAVING AN AFFINITY FOR THE HYDROGEN FLUORIDE, SAID METHOD COMPRISING THE STEPS OF: FLUIDIZING A COLUMN OF PARTICLES HAVING AN AVERAGE PARTICLE SIZE OF 20 TO 300 MICRONS OF A SOLID SELECTED FROM THE GROUP CONSISTING OF FINE-GRAIN ALUMINA, SODIUM ALUMINATE AND MIXTURES THEREOF WITH A GAS STREAM CONTAINING SAID HYDROGEN FLUORIDE IN AN AMOUNT UPWARDS OF 20 MG/M3 STP, SAID GAS STREAM BEING INTRODUCED AT A RATE SUFFICIENT TO PROVIDE A GAS VELOCITY WITHIN THE COLUMN WHICH IS 1 TO 5 METERS/SECOND TO PRODUCE AND MAINTAIN AN EXPANDED FLUID BED WITH A CONTINUOUS SOLIDS-CONCENTRATION GRADIENT EXTENDING OVER THE ENTIRE LENGTH OF THE COLUMN FROM THE GAS INLET OF THE BED TO THE GAS OUTLET THEREOF AND SUBSTANTIALLY FREE FROM A DEMARCATION BETWEEN A LAYER OF SAID SOLID AND FREE SPACE, THE TEMPERATURE OF THE GAS INTRODUCED INTO SAID BED BEING ADJUSTED TO SUBSTANTIALLY 50* TO 100*C, WITHDRAWING THE FLUIDIZING GAS UPON PASSAGE THROUGH SAID BED TOGETHER WITH A MAIN PROPORTION OF SOLIDS UPWARDLY DISCHARGED THEREFROM IN ENTRAINMENT WITH THE WITHDRAWN GAS, SEPARATING THE SOLID PARTICLES FROM SAID WITHDRAWN GAS BY CYCLONE SEDIMENTATION AND DISCHARGING A PURIFIED GAS SUBSTANTIALLY FREE FROM HF, AND RECYCLING THE SEPARATED PARTICLES TO SAID FLUID BED IN AN AMOUNT OF 5 TO 100 TIMES THE SOLIDS CONTENT OF THE FLUIDIZED BED.
Claim 2
Dependent Claim
234 words
A PROCESS FOR REMOVING HYDROGEN FLUORIDE FROM A GAS STREAM BY TREATING THE GAS STREAM WITH A SOLID HAVING AN AFFINITY FOR THE HYDROGEN FLUORIDE, SAID METHOD COMPRISING THE STEPS OF: FLUIDIZING A COLUMN OF PARTICLES HAVING AN AVERAGE PARTICLE SIZE OF 20 TO 300 MICRONS OF A SOLID SELECTED FROM THE GROUP CONSISTING OF FINE-GRAIN ALUMINA, SODIUM ALUMINATE AND MIXTURES THEREOF WITH A GAS STREAM CONTAINING SAID HYDROGEN FLUORIDE IN AN AMOUNT UPWARDS OF 20 MG/M3 STP, SAID GAS STREAM BEING INTRODUCED AT A RATE SUFFICIENT TO PROVIDE A GAS VELOCITY WITHIN THE COLUMN WHICH IS 1 TO 5 METERS/SECOND TO PRODUCE AND MAINTAIN AN EXPANDED FLUID BED WITH A CONTINUOUS SOLIDS-CONCENTRATION GRADIENT EXTENDING OVER THE ENTIRE LENGTH OF THE COLUMN FROM THE GAS INLET OF THE BED TO THE GAS OUTLET THEREOF AND SUBSTANTIALLY FREE FROM A DEMARCATION BETWEEN A LAYER OF SAID SOLID AND FREE SPACE, THE TEMPERATURE OF THE GAS INTRODUCED INTO SAID BED BEING ADJUSTED TO SUBSTANTIALLY 50* TO 100*C, WITHDRAWING THE FLUIDIZING GAS UPON PASSAGE THROUGH SAID BED TOGETHER WITH A MAIN PROPORTION OF SOLIDS UPWARDLY DISCHARGED THEREFROM IN ENTRAINMENT WITH THE WITHDRAWN GAS, SEPARATING THE SOLID PARTICLES FROM SAID WITHDRAWN GAS BY CYCLONE SEDIMENTATION AND DISCHARGING A PURIFIED GAS SUBSTANTIALLY FREE FROM HF, AND RECYCLING THE SEPARATED PARTICLES TO SAID FLUID BED IN AN AMOUNT OF 5 TO 100 TIMES THE SOLIDS CONTENT OF THE FLUIDIZED BED.
Claim 3
Dependent Claim
17 words
The process defined in claim 1 wherein the average solids concentration ranges between 10 and 300 kg/m3.
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) | 1978-09-22 | 1979-03-24 | 1979-09-23 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-09-22 | 1983-03-24 | 1983-09-23 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-09-22 | 1987-03-24 | 1987-09-23 | $7700.00 | Window Closed / Lapsed |