Patent US5313108A successfully refreshed from Google Patents.
US3716625A
Expired / Lapsed
US
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Process for the production of nitric acid with a concentration of over 70 percent by weight
Assignee: Bamag Verfahrenstechnik GmbH
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Filing: 1970-02-26
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Granted: 1973-02-13
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Expires: 1990-02-26
Abstract
Abstract Process of preparing nitric acid (having a concentration of over 70 percent by weight) by catalytically oxidizing ammonia with air to form NO2, absorbing the NO2 in water or aqueous nitric acid, increasing the partial pressure of the NO2 partly by compression and partly by passage through the absorption stage, washing out the residual NO2 with 60-70 percent nitric acid and recycling the same into the absorption stage, and blowing out the NO2 through the nitrous gas products of the ammonia oxidation in a degasification stage arranged ahead of the absorption stage.
Inventors
- 👤 Berghaus G Oberste
- 👤 C Karau
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-01 20:47
CPC Classifications
C; C01; C01B; C01B21/00; C01B21/20; C01B21/24; C01B21/26
Claims Analysis
Total Claims: 17
Claim 1
Independent Claim
189 words
In a process of obtaining nitric acid from the gases produced by ammonia oxidation to nitrogen oxides, wherein i. the product gas stream from the ammonia oxidation is cooled to condense and remove water from the stream, with secondary air for oxidation of said nitrogen oxides being added to the gas stream either prior to or subsequent to said cooling, ii. the oxidized gas stream from (i) is treated with the condensate from (i) in an absorption stage to form nitric acid, iii. the gas stream emitted from the absorption stage in (ii) is washed with a nitric acid wash liquid to rEmove residual nitrogen oxides, and iv. the wash liquid from (iii) is gas stripped to remove the nitrogen oxides, which nitrogen oxides are then returned to the absorption stage, the improvement comprising using as said wash liquid in step (iii) a nitric acid having a concentration of 60 to 75 weight percent, and using as a stripping gas for step (iv) the cooled gas stream of step (i) from which the water has been condensed and removed, said stripping being at a higher temperature than said washing.
Claim 2
Dependent Claim
189 words
In a process of obtaining nitric acid from the gases produced by ammonia oxidation to nitrogen oxides, wherein i. the product gas stream from the ammonia oxidation is cooled to condense and remove water from the stream, with secondary air for oxidation of said nitrogen oxides being added to the gas stream either prior to or subsequent to said cooling, ii. the oxidized gas stream from (i) is treated with the condensate from (i) in an absorption stage to form nitric acid, iii. the gas stream emitted from the absorption stage in (ii) is washed with a nitric acid wash liquid to rEmove residual nitrogen oxides, and iv. the wash liquid from (iii) is gas stripped to remove the nitrogen oxides, which nitrogen oxides are then returned to the absorption stage, the improvement comprising using as said wash liquid in step (iii) a nitric acid having a concentration of 60 to 75 weight percent, and using as a stripping gas for step (iv) the cooled gas stream of step (i) from which the water has been condensed and removed, said stripping being at a higher temperature than said washing.
Claim 3
Dependent Claim
33 words
The improved process of claim 1 wherein the stripping is conducted at about the same pressure as the absorption stage, and the stripped wash liquid is cooled and recycled to the washing stage.
Claim 4
Dependent Claim
22 words
The improved process of claim 1 wherein the product acid formed in (ii) is degasified by stripping it with an air stream.
Claim 5
Dependent Claim
64 words
The improved process of claim 1 wherein a portion of the nitric acid wash liquid that has been stripped in (iv) is further stripped with an air stream, following which at least a portion of the liquid is cooled and then used to further wash the gas stream emitted from (iii) so as to remove more of the residual nitrogen oxides from that stream.
Claim 6
Dependent Claim
112 words
The improved process of claim 4 wherein the concentration of the nitric acid wash liquid used in (iii) is the same as the concentration of the nitric acid formed in (ii), and the portion of the wash liquid that is further stripped with an air stream is so stripped while in admixture with the nitric acid formed in (ii), part of the air-stripped mixed acid stream is cooled and then used to further wash the gas stream emitted from (ii) so as to remove more of the residual nitrogen oxides from that stream, and the remaining portion of the air-stripped mixed acid stream is removed from the process as product nitric acid.
Claim 7
Dependent Claim
76 words
The improved process of claim 5 wherein the cooling of the portion of the air-stripped mixed acid stream that is to be used to further wash the gas stream emitted from (iii) is effective to lower the temperature of that portion to 0* to -20* C., and said portion, after being used for said further washing, is then returned to the air-stripping stage and is stripped while in admixture with the nitric acid formed in (ii).
Claim 8
Dependent Claim
39 words
The improved process of claim 1 wherein the nitric acid wash liquid from (iii), prior to being conducted to step (iv), is heated through indirect heat exchange by using it as cooling medium to effect the cooling in (i).
Claim 9
Dependent Claim
67 words
The improved process of claim 1 wherein the concentration of the nitric acid formed in (ii) is superazeotropic, said acid is degasified by stripping it with a secondary air stream and is then conducted to a rectifier wherein it is divided into a high percentage nitric acid overhead and an azeotropic nitric acid bottoms, and said bottoms fraction is used as nitric acid wash liquid in (iii).
Claim 10
Dependent Claim
23 words
The improved process of claim 1 wherein the ammonia oxidation is conducted at a pressure equal to or below the absorption stage pressure.
Claim 11
Dependent Claim
51 words
The improved process of claim 9 wherein the ammonia oxidation is conducted at about the same pressure as the absorption stage, and the secondary air is added to the gas stream from the ammonia oxidation after said stream has been both cooled and used to strip the wash liquid in (iv).
Claim 12
Dependent Claim
56 words
The improved process of claim 9 wherein the gas stream from the ammonia oxidation is compressed before being subjected to the absorption stage, the absorption stage is conducted at a higher pressure than the ammonia oxidation, and the secondary air is added to the gas stream from the ammonia oxidation before said gas stream is compressed.
Claim 13
Dependent Claim
69 words
The improved process of claim 9 wherein the ammonia oxidation is conducted at about the same pressure as the absorption stage, a portion of the nitric acid wash liquid that has been stripped in (iv) is further stripped with a secondary air stream at a lower pressure than the absorption stage pressure, and the secondary air stream used to strIp the acid is then compressed and conducted to (i).
Claim 14
Dependent Claim
19 words
The improved process of claim 1 wherein (iii) and (iv) are conducted in filler body columns without internal circulation.
Claim 15
Dependent Claim
30 words
The improved process of claim 6 wherein (iii) and (iv) and the further washing of the gas stream emitted from (iii) are conducted in filler body columns without internal circulation.
Claim 16
Dependent Claim
21 words
The improved process of claim 1 wherein the nitric acid formed in (ii) has a concentration of over 70 weight percent.
Claim 17
Dependent Claim
74 words
The improved process of claim 15 wherein the ammonia oxidation is conducted at a temperature of 800* to 950* C., the condensate from (i) has an acid concentration of 20 to 40 percent, the absorption stage pressure is in the range of about 3 atmospheres to 10 atmospheres, and the nitric acid wash liquid that has been subjected to the stripping operation of (iv) has an N2O4 content of 0.5 to 2 weight percent.
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) | 1976-02-13 | 1976-08-14 | 1977-02-13 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-02-13 | 1980-08-14 | 1981-02-13 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-02-13 | 1984-08-14 | 1985-02-13 | $7700.00 | Window Closed / Lapsed |