DEP0034119DA - Process for the absorption of nitrous gases for the production of nitric acid - Google Patents
Process for the absorption of nitrous gases for the production of nitric acidInfo
- Publication number
- DEP0034119DA DEP0034119DA DEP0034119DA DE P0034119D A DEP0034119D A DE P0034119DA DE P0034119D A DEP0034119D A DE P0034119DA
- Authority
- DE
- Germany
- Prior art keywords
- absorption
- gases
- nitrous
- nitric acid
- nitrous gases
- 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
- 239000007789 gas Substances 0.000 title claims description 16
- 238000010521 absorption reaction Methods 0.000 title claims description 15
- GQPLMRYTRLFLPF-UHFFFAOYSA-N nitrous oxide Inorganic materials [O-][N+]#N GQPLMRYTRLFLPF-UHFFFAOYSA-N 0.000 title claims description 14
- GRYLNZFGIOXLOG-UHFFFAOYSA-N nitric acid Chemical compound O[N+]([O-])=O GRYLNZFGIOXLOG-UHFFFAOYSA-N 0.000 title claims description 5
- 238000000034 method Methods 0.000 title claims description 3
- 238000004519 manufacturing process Methods 0.000 title description 2
- QGZKDVFQNNGYKY-UHFFFAOYSA-N ammonia Chemical compound N QGZKDVFQNNGYKY-UHFFFAOYSA-N 0.000 claims description 4
- 238000001704 evaporation Methods 0.000 claims description 2
- 239000007788 liquid Substances 0.000 claims description 2
- 238000007084 catalytic combustion reaction Methods 0.000 claims 1
- MWUXSHHQAYIFBG-UHFFFAOYSA-N Nitrogen oxide Substances O=[N] MWUXSHHQAYIFBG-UHFFFAOYSA-N 0.000 description 5
- 238000001816 cooling Methods 0.000 description 3
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 3
- 230000015572 biosynthetic process Effects 0.000 description 2
- 238000006243 chemical reaction Methods 0.000 description 2
- 229910052813 nitrogen oxide Inorganic materials 0.000 description 2
- 230000003647 oxidation Effects 0.000 description 2
- 238000007254 oxidation reaction Methods 0.000 description 2
- 238000005057 refrigeration Methods 0.000 description 2
- 230000001133 acceleration Effects 0.000 description 1
- 239000002253 acid Substances 0.000 description 1
- 239000000567 combustion gas Substances 0.000 description 1
- 238000002485 combustion reaction Methods 0.000 description 1
- 238000007906 compression Methods 0.000 description 1
- 239000000498 cooling water Substances 0.000 description 1
- 230000000875 corresponding Effects 0.000 description 1
- 238000000354 decomposition reaction Methods 0.000 description 1
- 238000004090 dissolution Methods 0.000 description 1
- 239000003337 fertilizer Substances 0.000 description 1
- 238000005755 formation reaction Methods 0.000 description 1
- 238000010438 heat treatment Methods 0.000 description 1
- 239000002184 metal Substances 0.000 description 1
- -1 nitrate-nitrogen Chemical compound 0.000 description 1
- 150000002823 nitrates Chemical group 0.000 description 1
- 238000005121 nitriding Methods 0.000 description 1
- 230000001340 slower Effects 0.000 description 1
- 238000003786 synthesis reaction Methods 0.000 description 1
- 230000002194 synthesizing Effects 0.000 description 1
- 238000011144 upstream manufacturing Methods 0.000 description 1
Description
Nitrose Gase, wie sie beispielsweise bei der Ammoniakverbrennung, bei der Zersetzung von Nitraten, bei der Durchführung von Nitrierprozessen oder bei der Ausführung der Metallheizung entstehen, lassen sich nur schwer so vollständig mit Wasser absorbieren, wie es mit Rücksicht auf die Betriebsausbeute oder gewerbepolizeilichen Vorschriften nötig ist. Zur Absorption von nitrosen Gasen zwecks Überführung in Salpetersäure sind sehr umfangreiche Absorptionsanlagen erforderlich, wenn man die nitrosen Gase mit ausreichender Vollständigkeit aus den Gasen entfernen will. Die Vollständigkeit der Salpetersäure-Bildung wird durch die auftretende Oxydations- und Lösungswärme stark behindert.Nitrous gases, such as those produced during the combustion of ammonia, the decomposition of nitrates, the implementation of nitriding processes or the implementation of metal heating, are difficult to absorb with water as completely as is necessary with regard to the operating yield or industrial police regulations is. To absorb nitrous gases for the purpose of converting them into nitric acid, very extensive absorption systems are required if the nitrous gases are to be removed from the gases with sufficient completeness. The completeness of the nitric acid formation is severely hindered by the heat of oxidation and dissolution that occurs.
Solange die Gase einen ausreichend hohen Gehalt an Stickstoffoxyden aufweisen (NO, NO(sub)2 u.a.), verlaufen Absorption und Oxydation zu Salpetersäure mit befriedigender Sicherheit. Mit zunehmender Verarmung der Gase verlangsamt sich die Absorption in starker Weise, weil die Absorptionsgeschwindigkeit annähernd der 3.Potenz der Nitrose-Konzentration proportional ist.As long as the gases have a sufficiently high content of nitrogen oxides (NO, NO (sub) 2, etc.), absorption and oxidation to nitric acid proceed with satisfactory reliability. With increasing depletion of the gases, the absorption slows down considerably, because the absorption speed is approximately proportional to the 3rd power of the nitrose concentration.
Da die Absorptionsgeschwindigkeit nitroser Gase der 5.Potenz ihrer Temperatur umgekehrt proportional ist, wurde bereits vorgeschlagen, nitrose Gase bei möglichst tiefen Temperaturen mit Wasser zu absorbieren. Diese Temperaturen lagen teilweise in der Nähe des Stickoxyd-Verflüssigungspunktes (vgl. z.B. Bodio). Eine derartige Arbeitsweise führt zwar zu einer Beschleunigung und Verbesserung der Absorption, verursacht aber hinsichtlich der Gaskühlung sehr große und zum Teil völlig überflüssige Kosten. Unter diesen Umständen wird nämlich auch solche Reaktionswärme bei tiefen Temperaturen abgeführt, die sich im Bereich der anfangs hohen Nitrose-Konzentration mit gewöhnlichem Kühlwasser oder durch einfache Luftkühlung hätte beseitigen lassen.Since the rate of absorption of nitrous gases is inversely proportional to the 5th power of their temperature, it has already been proposed to absorb nitrous gases with water at the lowest possible temperatures. These temperatures were partly in the vicinity of the nitrogen oxide liquefaction point (see e.g. Bodio). Such a mode of operation leads to an acceleration and improvement of the absorption, but causes very high and in some cases completely superfluous costs with regard to the gas cooling. Under these circumstances, such heat of reaction is also dissipated at low temperatures that could have been eliminated in the range of the initially high nitrous concentration with ordinary cooling water or by simple air cooling.
Es wurde gefunden, dass sich mit sehr geringem Kälteaufwand eine praktisch vollständige Absorption von nitrosen Gasen erreichen lässt, wenn erst die fast erschöpften Gase, die nur noch annähernd 10% ihres ursprünglichen Nitrosegehaltes aufweisen, bei ihrer Absorption tief gekühlt werden. In den der Restabsorption vorgeschalteten Absorptionstürmen kann hierbei der Hauptteil der entsprechenden Reaktionswärme durch einfache Luft und/oder Wasserkühlung vernichtet werden. Auf diese Weise kann der Abgas-Nitrosegehalt von Säurebetrieben mit überraschend geringem Kälte-Aufwand bereits in einer verhältnissmäßig sehr kleinen Absorptionsanlage auf weniger als 0,2% NO vermindert werden.It has been found that practically complete absorption of nitrous gases can be achieved with very little expenditure of cold, if only the almost exhausted gases have approximately 10% of their original nitrous content, are deeply refrigerated when they are absorbed. In the absorption towers upstream of the residual absorption, the main part of the corresponding heat of reaction can be destroyed by simple air and / or water cooling. In this way, the exhaust gas nitrous content of acid plants can be reduced to less than 0.2% NO in a relatively very small absorption plant with surprisingly little refrigeration expenditure.
Bei Verarbeitung von Ammoniak-Verbrennungsgasen, wie sie beispielsweise zur Herstellung von Nitrat-Stickstoffdüngemitteln in größtem Umfang verwendet werden, genügt die Kältemenge, die sich durch die adiabatische Verdampfung des zu verbrennenden, bei der NH(sub)3-Synthese in flüssigem Zustand gewonnenen Ammoniak ergibt. Es kann aber auch künstliche Kälte aus anderen Quellen, beispielsweise aus Absorptions- oder Kompressions-Kältemaschinen, zur erfindungsgemäßen Absorption nitroser Gase benutzt werden.When processing ammonia combustion gases, such as those used to a large extent for the production of nitrate-nitrogen fertilizers, the amount of cold that is generated by the adiabatic evaporation of the ammonia to be burned, which is obtained in the liquid state in the NH (sub) 3 synthesis, is sufficient results. However, artificial cold from other sources, for example from absorption or compression refrigeration machines, can also be used for the absorption of nitrous gases according to the invention.
Claims (2)
Family
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