AU714625B2 - Process of removing NOx from nitrosyl hydrogensulfate - Google Patents
Process of removing NOx from nitrosyl hydrogensulfate Download PDFInfo
- Publication number
- AU714625B2 AU714625B2 AU63545/96A AU6354596A AU714625B2 AU 714625 B2 AU714625 B2 AU 714625B2 AU 63545/96 A AU63545/96 A AU 63545/96A AU 6354596 A AU6354596 A AU 6354596A AU 714625 B2 AU714625 B2 AU 714625B2
- Authority
- AU
- Australia
- Prior art keywords
- sulfuric acid
- reactor
- withdrawn
- nox
- saturation
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
- VQTGUFBGYOIUFS-UHFFFAOYSA-N nitrosylsulfuric acid Chemical compound OS(=O)(=O)ON=O VQTGUFBGYOIUFS-UHFFFAOYSA-N 0.000 title claims description 27
- 238000000034 method Methods 0.000 title claims description 20
- QAOWNCQODCNURD-UHFFFAOYSA-N Sulfuric acid Chemical compound OS(O)(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-N 0.000 claims description 123
- 238000002156 mixing Methods 0.000 claims description 24
- 229920006395 saturated elastomer Polymers 0.000 claims description 7
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 7
- 239000000498 cooling water Substances 0.000 claims description 3
- 238000001816 cooling Methods 0.000 claims 1
- 239000007789 gas Substances 0.000 description 18
- MWUXSHHQAYIFBG-UHFFFAOYSA-N nitrogen oxide Inorganic materials O=[N] MWUXSHHQAYIFBG-UHFFFAOYSA-N 0.000 description 12
- 239000002253 acid Substances 0.000 description 9
- 238000006243 chemical reaction Methods 0.000 description 7
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 6
- 238000004519 manufacturing process Methods 0.000 description 5
- 239000000203 mixture Substances 0.000 description 5
- 230000007062 hydrolysis Effects 0.000 description 3
- 238000006460 hydrolysis reaction Methods 0.000 description 3
- 229910052757 nitrogen Inorganic materials 0.000 description 3
- 239000007864 aqueous solution Substances 0.000 description 2
- ILGQIWVECKRNLJ-UHFFFAOYSA-N nitroso hydrogen sulfate;sulfuric acid Chemical compound OS(O)(=O)=O.OS(=O)(=O)ON=O ILGQIWVECKRNLJ-UHFFFAOYSA-N 0.000 description 2
- 238000006479 redox reaction Methods 0.000 description 2
- UGFAIRIUMAVXCW-UHFFFAOYSA-N Carbon monoxide Chemical compound [O+]#[C-] UGFAIRIUMAVXCW-UHFFFAOYSA-N 0.000 description 1
- QAOWNCQODCNURD-UHFFFAOYSA-L Sulfate Chemical compound [O-]S([O-])(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-L 0.000 description 1
- NINIDFKCEFEMDL-UHFFFAOYSA-N Sulfur Chemical compound [S] NINIDFKCEFEMDL-UHFFFAOYSA-N 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 239000003054 catalyst Substances 0.000 description 1
- 239000003638 chemical reducing agent Substances 0.000 description 1
- 239000003795 chemical substances by application Substances 0.000 description 1
- 238000002485 combustion reaction Methods 0.000 description 1
- 150000001875 compounds Chemical class 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 238000007865 diluting Methods 0.000 description 1
- 239000003546 flue gas Substances 0.000 description 1
- 239000011261 inert gas Substances 0.000 description 1
- 238000010310 metallurgical process Methods 0.000 description 1
- 230000000802 nitrating effect Effects 0.000 description 1
- 230000001473 noxious effect Effects 0.000 description 1
- 230000003647 oxidation Effects 0.000 description 1
- 238000007254 oxidation reaction Methods 0.000 description 1
- 238000000926 separation method Methods 0.000 description 1
- 239000000243 solution Substances 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- 229910052717 sulfur Inorganic materials 0.000 description 1
- 239000011593 sulfur Substances 0.000 description 1
Classifications
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
- C01B17/00—Sulfur; Compounds thereof
- C01B17/69—Sulfur trioxide; Sulfuric acid
- C01B17/90—Separation; Purification
- C01B17/94—Recovery from nitration acids
Landscapes
- Chemical & Material Sciences (AREA)
- Organic Chemistry (AREA)
- Inorganic Chemistry (AREA)
- Treating Waste Gases (AREA)
Description
PCT/EP96/01719 Translation of new description pages 1 and la METALLGESELLSCHAFT AG Reuterweg 14 June 23, 1997 WGN-zo-dvz D-60323 Frankfurt/Main Case No.: 94 00 48 Process of Removing NOx from Nitrosyl Hydrogensulfate p 95 p p
S
Description This invention relates to a process of removing NOx from nitrosyl hydrogensulfate by mixing nitrosyl hydrogensulfate in a mixing reactor with sulfuric acid, which is saturated with
SO
2 where a sulfuric acid containing N 2 0 3 is withdrawn from the mixing reactor, and a stripping gas is passed through the withdrawn sulfuric acid.
Such process is known from GB-A-0,348,866. For the expulsion of residual nitrogen oxides from the sulfuric acid flue gas or an inert gas is passed through the sulfuric acid, with the temperature lying in the range from 100 to 200 0 C. In Database WPI, AN91-108 779 it is described that NOx-containing sulfuric acid (spent acid) is mixed with circulating acid and added to a so-called second column. In the lower portion of the second column SO 2 gas is introduced, which comes from a laso-called first column. Part of the circulating acid withdrawn from the second column is added to the first column, to which a surplus of SO 2 is supplied. The exhaust gas of the second column contains no SO 2 and the sulfuric acid withdrawn from the first column, which is free from NOx, contains wt-% H 2
SO
4 Mixing the spent acid with sulfuric acid saturated with SO 2 does not take place in the known process.
The object underlying the invention is to remove NO x from nitrosyl hydrogensulfate in a simple and inexpensive way. In accordance with the invention this is accomplished in the above-stated process in that the N203-containing sulfuric acid withdrawn from the mixing reactor is added to a saturation reactor, where in the lower portion of the saturation reactor an S0 2 -containing gas is introduced at the same time, which at least in part flows upwards through the N 2 0 3 -containing sulfuric acid, that water is introduced into the saturation reactor, and from the saturation reactor a virtually NOx-free sulfuric acid saturated with SO 2 is withdrawn, which has a H 2 S0 4 concentration of 5 to 60 and a partial stream of which is passed into the mixing reactor, where
SO
2 is supplied to the mixing reactor in a stoichiometric surplus of at least 2 wt-% with reference to the NO x content of nitrosyl hydrogensulfate.
-2- In accordance with the invention, the term NOx refers to a mixture of NO and NO2. NOx is present in sulfuric acid as dissolved nitrosyl hydrogensulfate. Nitrosyl hydrogensulfate is formed from NO, which is contained in SO2-containing gas.
The S0 2 -containing gas originates for instance from a roasting, sulfur combustion, sulfate separation or metallurgical process. NO is oxidized at the oxidation catalyst of a sulfuric acid plant for up to 50 to form NO 2 The mixture of NO and NO2 is reacted with sulfuric acid to form nitrosyl hydrogensulfate as follows: NO NO 2 2H 2 S0 4 2HNOSO 4
H
2 0 It is known that SO 2 reacts with nitrosyl hydrogensulfate by forming sulfuric acid and nitrogen oxides: SO2 2HNOSO 4 2H20 3H 2 S0 4 2NO In the production of sulfuric acid nitrosyl hydrogensulfate, usually with a NOx content of more than 2.5 is separated as a condensate. The NO, content is present in the condensate as nitrosyl hydrogensulfate in addition to sulfuric acid.
In formal terms, nitrosyl hydrogensulfate can be reacted with
SO
2 and water to form sulfuric acid and N2. The redox reaction takes place between the dissolved SO 2 in the form of 2- SO32- with the N203 in the form of NO2 which was produced in the hydrolysis of nitrosyl hydrogensulfate. The reduction of the nitrogen oxides NO and NO2 to nitrogen is effected in the 3 hydrolysis of nitrosyl hydrogensulfate with dilute, S0 2 -saturated sulfuric acid in that in the diluting solution the reducing agent is provided in the form of S0 3 2 in an overstoichiometric amount, so that the equilibrium is shifted towards the formation of N 2 It is an advantage of the present invention that the amount sulfuric acid present in a condensate containing nitrosyl hydrogensulfate can be recirculated to a sulfuric acid production without any NOx. In accordance with the conventional processes the condensate is withdrawn from the process and must be subjected to a treatment or be disposed of. A particular advantage of the inventive process consists in that nitrogen is formed from the noxious substance NOx and is discharged together with the exhaust gas.
Preferably, SO 2 is supplied to the mixing reactor in a stoichiometric surplus of at least 5 wt-% with reference to the NOx content of nitrosyl hydrogensulfate. With this surplus of
SO
2 a good result is achieved in the reduction of the NOx content. SO 2 is not lost as a result of the reduction of NOx to N 2 but is oxidized to form S042-. Excess S02 can be supplied to a plant for the production of sulfuric acid, so that an extensive treatment is not necessary.
Advantageously, the sulfuric acid concentration after the addition of S02 is 5 to 30 In this range of the sulfuric acid concentration particularly good results are achieved for the reduction of NOx to N 2 In accordance with an advantageous aspect of the invention gaseous SO 2 is brought into aqueous solution in a saturation reactor designed as packed column, and is combined with the NOx-containing sulfuric acid as an aqueous solution. The SO 2 saturation is promoted by operating the saturator under an increased gas pressure.
4 In accordance with the invention, the NOx content of a NO:containing sulfuric acid (nitrosyl hydrogensulfate) or a NO x containing sulfuric acid mixture is reduced. The process in accordance with the invention can advantageously not only be applied to NOx-containing sulfuric acid, but with very good results also to mixtures containing NOx and sulfuric acid, such as nitrating acid or sulfuric acid contaminated with other compounds.
Embodiments of the invention will be explained in detail with reference to the drawing and examples. The drawing represents a flow diagram of the process.
The most important parts of the process are the reactor (X) for the saturation of SO 2 and the mixing reactor for hydrolysis and redox reaction of nitrosyl hydrogensulfate with SO-containing dilute sulfuric acid. S0 2 -containing roaster gas is introduced via line and water is introduced via line into the lower portion of the saturation reactor Via line nitrosyl hydrogensulfate or condensate containing said acid is supplied to the mixing reactor In principle, dilute sulfuric acid is circulated between the reactors and via lines and Sulfuric acid formed is withdrawn via line and N 2 is discharged together with the exhaust gas via line Via line sulfuric acid is withdrawn from the saturation reactor and passed through a pump Said sulfuric acid is saturated with SO2, is virtually NOx-free, and has a H 2 S0 4 concentration of 5 to 60 wt-% and mostly not more than 35 wt- From the pump the sulfuric acid is withdrawn via line A partial stream of the acid is supplied to the mixing reactor via line The acid withdrawn from the reactor via line which still contains N 2 0 3 is supplied to the indirect cooler Via line the cooler is supplied with cooling water, which is withdrawn via line (11).
I 5 Cooled sulfuric acid is introduced into the saturation reactor via line The reactor contains at least one packed bed. In the reactor upwardly flowing S02-containing gas serves as stripping gas for removing residual nitrogen oxides from the sulfuric acid supplied via line Example 1: In an arrangement as shown in the drawing the procedure is as follows: Via line 240 kg/h condensate with a nitrosyl hydrogensulfate content of 9.5 HNOSO 4 corresponding to 6.8 kg/h
N
2 0 3 are introduced into the mixing reactor The condensate comes from a sulfuric acid production. Via line (6A) an S0 2 -saturated sulfuric acid with 20 wt-% H 2
SO
4 is supplied to the reactor the condensate and S02-saturated sulfuric acid are mixed. The dissolved SO 2 reacts with nitrosyl hydrogensulfate to form sulfuric acid and nitrogen. The mixture is withdrawn via line and behind the block cooler still has a content of 465 mg N 2 0 3 which corresponds to a content of 2.0 kg N 2 0 3 In the saturation reactor the circulating sulfuric acid is saturated with SO 2 where SO2-containing roaster gas, which contains 0.28 g/h NOx, is supplied via line The concentration of sulfuric acid is adjusted to 20 wt-% H 2 S0 4 by means of a controlled addition of water through line The roaster gas leaving the reactor via line has a reduced SO 2 content and is returned to the sulfuric acid production as a wet gas. The gas in line (2) contains 3.125 mg NOx/Nm corresponding to 2.0 kg N 2 0 3 per hour. In the sulfuric acid in lines (6B) and (6A) NOx could no longer be detected. The denitrating conversion was 71.75
I
6 Example 2: Example 2 is carried out like Example 1, but with the following differences: SO-saturated sulfuric acid containing 16 wt-% H 2 S0 4 is supplied to the mixing reactor via line Behind the block cooler the sulfuric acid in line contains 400 mg N 2 0 3 /1 corresponding to 1.7 kg N 2 0 3 After a controlled addition of water through line a sulfuric acid with a concentration of 16 wt-% H 2 S0 4 is produced in the saturation reactor and withdrawn via line This sulfuric acid is NOx-free. The denitrating conversion was 80.23 Example 3: The procedure is as in Examples 1 and 2, but with the following differences: Via line 190 kg/h condensate are introduced into the mixing reactor The condensate has a nitrosyl hydrogensulfate content of 7.5 wt-% HNOSO 4 corresponding to 4.3 kg N 2 0 3 per hour. The condensate is mixed in the mixing reactor (Y) with a 33 SO 2 -saturated sulfuric acid from line Behind the block cooler the sulfuric acid in line contains 350 mg N 2 0 3 /1 corresponding to 1.5 kg N 2 0 3 In the saturation reactor a sulfuric acid with a concentration of 33 wt-% H 2 S0 4 is adjusted through a controlled addition of water and withdrawn through line The acid is NOx-free.
The SO 2 gas withdrawn via line contains 4700 mg NOx/Nm 3 corresponding to 3.0 kg N 2 0 3 The denitrating conversion is 34.5%.
The comparison of Examples 1, 2 and 3 clearly illustrates that there is a dependence between the Nox conversion and the concentration of the circulating sulfuric acid. The higher 7 the concentration of the circulating sulfuric acid, the lower the denitrating conversion.
The advantage of a rather high denitrating conversion consists in the fact that the circulating amount of NO x is lower. NOx which is not discharged from the denitrating plant gets back to the main gas stream of the sulfuric acid plant, where nitrosyl hydrogensulfate is formed again. A lower denitrating conversion requires a larger denitrating plant.
Claims (6)
1. A process of removing NOx from nitrosyl hydrogensulfate by mixing nitrosyl hydrogensulfate in a mixing reactor with sulfuric acid, which is saturated with SO 2 where a N 2 0 3 -containing sulfuric acid is withdrawn from the mix- ing reactor, and a stripping gas is passed through the withdrawn sulfuric acid, characterized in that the N 2 0 3 containing sulfuric acid withdrawn from the mixing reac- tor is added to a saturation reactor, where in the lower portion of the saturation reactor a SO2-containing gas is introduced at the same time, which at least partly flows upwards through the N 2 0 3 -containing sulfuric acid, that water is introduced into the saturation reactor, and from the saturation reactor an S0 2 -saturated, virtually NOx- free sulfuric acid with a H 2 S0 4 concentration of 5 to wt-% is withdrawn, a partial stream of which is intro- duced into the mixing reactor, where S02 in a stoi- chiometric surplus of at least 2 wt-% with reference to the NOx content of nitrosyl hydrogensulfate is supplied to the mixing reactor.
2. The process as claimed in claim 1, characterized in that the sulfuric acid withdrawn from the mixing reactor is cooled before being introduced into the saturation reac- tor.
3. The process as claimed in claim 2, characterized in that the sulfuric acid withdrawn from the mixing reactor is indirectly cooled with cooling water, where heated cool- ing water is withdrawn from the indirect cooling system.
4. The process as claimed in claim 1 or one of the following claims, characterized in that through the partial stream of S0 2 -saturated sulfuric acid, SO 2 in a stoichiometric surplus of at least 5 wt-% with reference to the NOx con- A -9 tent of nitrosyl hydrogensulfate is supplied to the mix- ing reactor.
The process as claimed in claim 1 or one of the following claims, characterized in that S02-saturated sulfuric acid with a H 2 SO 4 content of 5 to 35 wt-% is withdrawn from the saturation reactor.
6. The process as claimed in one of claims 1 to 5, charac- terized in that the nitrosyl hydrogensulfate is obtained from a plant for producing sulfuric acid from SO2-con- taining roaster gas, and S02-containing roaster gas is introduced into the lower portion of the saturation reac- tor.
Applications Claiming Priority (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DE19516303 | 1995-05-04 | ||
| CA002260816A CA2260816C (en) | 1995-05-04 | 1996-07-16 | Process for removing nox from nitrosylsulphuric acid |
| PCT/EP1996/001719 WO1998002381A1 (en) | 1995-05-04 | 1996-07-16 | PROCESS FOR REMOVING NOx FROM NITROSYLSULPHURIC ACID |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| AU6354596A AU6354596A (en) | 1998-02-09 |
| AU714625B2 true AU714625B2 (en) | 2000-01-06 |
Family
ID=27170929
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| AU63545/96A Expired AU714625B2 (en) | 1995-05-04 | 1996-07-16 | Process of removing NOx from nitrosyl hydrogensulfate |
Country Status (7)
| Country | Link |
|---|---|
| EP (1) | EP0912441B1 (en) |
| JP (1) | JP4118333B2 (en) |
| AU (1) | AU714625B2 (en) |
| DE (1) | DE59605854D1 (en) |
| ES (1) | ES2152029T3 (en) |
| WO (1) | WO1998002381A1 (en) |
| ZA (1) | ZA963521B (en) |
Families Citing this family (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE19839674A1 (en) * | 1998-09-01 | 2000-03-02 | Metallgesellschaft Ag | Process for removing nitrogen oxides from nitrosylsulfuric acid |
| DE10050526A1 (en) * | 2000-10-11 | 2002-04-25 | Sachtleben Chemie Gmbh | Removal of nitrosylsulfuric acid from sulfuric acid process involves thermal cracking, preferably in existing roasting or combustion zone for sulfur dioxide production |
| JP4641255B2 (en) * | 2005-12-22 | 2011-03-02 | 住友精化株式会社 | Nitric oxide purification method |
| EP4067301A1 (en) | 2021-03-29 | 2022-10-05 | PLINKE GmbH | Process for recycling nitrogen oxides from nitrosyl sulfuric acid to produce concentrated or highly concentrated nitric acid and sulfuric acid |
Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB348866A (en) * | 1930-05-06 | 1931-05-21 | Ig Farbenindustrie Ag | An improvement relating to the purification of sulphuric acid |
Family Cites Families (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4155989A (en) * | 1977-11-14 | 1979-05-22 | Ciba-Geigy Corporation | Removal of nitric acid from nitric acid-sulfuric acid mixtures |
| SU1586996A1 (en) * | 1988-02-29 | 1990-08-23 | Горьковский Политехнический Институт | Method of denitration of spent sulfuric acid |
-
1996
- 1996-05-03 ZA ZA9603521A patent/ZA963521B/en unknown
- 1996-07-16 AU AU63545/96A patent/AU714625B2/en not_active Expired
- 1996-07-16 JP JP52152297A patent/JP4118333B2/en not_active Expired - Lifetime
- 1996-07-16 DE DE59605854T patent/DE59605854D1/en not_active Expired - Fee Related
- 1996-07-16 ES ES96922788T patent/ES2152029T3/en not_active Expired - Lifetime
- 1996-07-16 WO PCT/EP1996/001719 patent/WO1998002381A1/en active IP Right Grant
- 1996-07-16 EP EP96922788A patent/EP0912441B1/en not_active Expired - Lifetime
Patent Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB348866A (en) * | 1930-05-06 | 1931-05-21 | Ig Farbenindustrie Ag | An improvement relating to the purification of sulphuric acid |
Also Published As
| Publication number | Publication date |
|---|---|
| JP4118333B2 (en) | 2008-07-16 |
| EP0912441B1 (en) | 2000-09-06 |
| WO1998002381A1 (en) | 1998-01-22 |
| DE59605854D1 (en) | 2000-10-12 |
| ES2152029T3 (en) | 2001-01-16 |
| ZA963521B (en) | 1997-11-03 |
| AU6354596A (en) | 1998-02-09 |
| JP2001503366A (en) | 2001-03-13 |
| EP0912441A1 (en) | 1999-05-06 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| FGA | Letters patent sealed or granted (standard patent) | ||
| PC | Assignment registered |
Owner name: OUTOKUMPU OYJ Free format text: FORMER OWNER WAS: METALLGESELLSCHAFT AKTIENGESELLSCHAFT |