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WO2025210081A1 - Production sûre d'acide nitrique selon le procédé à pression unique - Google Patents

Production sûre d'acide nitrique selon le procédé à pression unique

Info

Publication number
WO2025210081A1
WO2025210081A1 PCT/EP2025/058975 EP2025058975W WO2025210081A1 WO 2025210081 A1 WO2025210081 A1 WO 2025210081A1 EP 2025058975 W EP2025058975 W EP 2025058975W WO 2025210081 A1 WO2025210081 A1 WO 2025210081A1
Authority
WO
WIPO (PCT)
Prior art keywords
condenser
acid
outlet
gas
nitric acid
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.)
Pending
Application number
PCT/EP2025/058975
Other languages
German (de)
English (en)
Inventor
Johannes DAMMEIER
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
ThyssenKrupp AG
ThyssenKrupp Industrial Solutions AG
Original Assignee
ThyssenKrupp AG
ThyssenKrupp Uhde GmbH
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Priority claimed from DE102024109405.2A external-priority patent/DE102024109405A1/de
Priority claimed from LU103274A external-priority patent/LU103274B1/de
Application filed by ThyssenKrupp AG, ThyssenKrupp Uhde GmbH filed Critical ThyssenKrupp AG
Publication of WO2025210081A1 publication Critical patent/WO2025210081A1/fr
Pending legal-status Critical Current
Anticipated expiration legal-status Critical

Links

Classifications

    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
    • C01B21/00—Nitrogen; Compounds thereof
    • C01B21/20—Nitrogen oxides; Oxyacids of nitrogen; Salts thereof
    • C01B21/24—Nitric oxide (NO)
    • C01B21/26—Preparation by catalytic or non-catalytic oxidation of ammonia
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
    • C01B21/00—Nitrogen; Compounds thereof
    • C01B21/20—Nitrogen oxides; Oxyacids of nitrogen; Salts thereof
    • C01B21/24—Nitric oxide (NO)
    • C01B21/26—Preparation by catalytic or non-catalytic oxidation of ammonia
    • C01B21/28—Apparatus

Definitions

  • the invention relates to a device and a method for preventing potentially dangerous deposits within a plant for the production of nitric acid.
  • Nitric acid is produced industrially using the Ostwald process.
  • the first step is the oxidation of ammonia to NO, followed by further oxidation and absorption to produce, for example, 60 wt.% nitric acid.
  • DE 10 2017 201 180 A1 shows a process for the production of nitric acid and a suitable plant for this purpose.
  • a process for producing nitric acid is known from US 7 118 723 B2.
  • Nitric acid production is known from US 5 985 230 A.
  • US 4 276 277 A discloses the production of concentrated nitric acid.
  • ammonium nitrate and/or ammonium nitrite may form within the device. Both are particularly critical in dry form, as they can be mechanically converted. Ammonium nitrite, which is more likely to form under alkaline ambient conditions, is generally more critical than ammonium nitrate, which is more likely to form under acidic conditions.
  • Such solids can be particularly critical if they enter the compressor between the condenser and the absorption tower or if they precipitate from the gas phase in the compressor as solids, as this is where mechanical stresses are most likely to occur.
  • Such compressors are used in a variant of the Ostwald process (“dual-pressure process”).
  • these deposits are also critical in devices using the indentation process without a compressor.
  • the indentation process there is no compression in the process; here the Ammonia oxidation takes place at the same pressure as absorption. Therefore, the pressure in the indentation process is often in the range of 7 to 11 bar, whereas in the dual-pressure process, the pressure for ammonia oxidation can be, for example, 4 to 5 bar and the pressure for absorption 11 to 13 bar.
  • Ammonia slip i.e., an incomplete conversion of ammonia to NO, can occur, for example, if the catalyst is damaged (in some places) or if there is an inhomogeneous flow over the catalyst. Ammonia slip occurs particularly during the start-up of nitric acid plants, as the primary catalyst has not yet reached its operating temperature and therefore exhibits lower reactivity.
  • the object of the invention is to ensure safety even in the event of ammonia slip.
  • the device according to the invention is used to produce nitric acid from ammonia using the pressure-injection process. This is the so-called Ostwald process.
  • the device comprises a first oxidation reactor, at least one first heat exchanger, a condenser, and an absorption tower.
  • the oxidation reactor is connected to the at least one first heat exchanger via a first connection for transferring the NOx gas mixture (the oxidation product).
  • first heat exchangers are operated in series to achieve sufficient cooling of the oxidation product.
  • the oxidation takes place at temperatures of around 1000°C. usually between 800 °C and 950 °C, while in the condenser the temperature is closer to 100 °C, usually between 50 °C and 60 °C.
  • the condenser has a first acid outlet. This is usually located on the underside of the condenser in the area of a collecting tank for the condensed nitric acid.
  • the first acid outlet is usually connected to a first acid inlet of the absorption tower via a first acid line.
  • the absorption tower has a second acid outlet.
  • the second acid outlet is connected to a product outlet via a second acid line.
  • a bleaching column and/or a storage tank, for example, can be arranged between the second acid outlet and the product outlet.
  • the absorption tower is usually constructed such that the first acid inlet is positioned so that the diluted nitric acid is brought into contact with the NO x -richer NO x gas in a region of the column with the corresponding acid concentration, thereby enriching it.
  • a water inlet is usually located at the top of the absorption tower. This ensures that the water (with the lowest nitric acid concentration) comes into contact with the NO x -poorest gas, improving absorption.
  • the NO x gas stream is fed in at the bottom, while the gas outlet is located at the top. The NO x -containing gas thus flows upwards, while the liquid flows downwards.
  • the first acid outlet or the second acid outlet is connected to the condenser and/or the third connection via a third acid line.
  • Nitric acid is thus sprayed into the NOx gas stream within a condensing temperature window in which no immediate evaporation occurs.
  • the advantage of using nitric acid over water is that an acidic level is maintained, which in turn leads to the preferential formation of ammonium nitrate over ammonium nitrite. If water is used, a basic environment can develop in the presence of ammonia, which disfavors the formation of ammonium nitrite over ammonium nitrate. Furthermore, the use of additional water leads to dilution of the nitric acid product, which is undesirable.
  • the acid can be conducted via the condenser sump, the absorption tower, or other tanks and lines. It is essential that the nitric acid ultimately originates from the first acid outlet or the second acid outlet, even if it is taken from a downstream storage tank, for example. Examples of these sources include a trickling acid tank, a buffer tank for off-spec nitric acid, a product acid tank, or a tank installed specifically for this purpose. Extraction from a nitric acid line is also possible, particularly the first acid line or the second acid line. The corresponding nitric acid sources are connected to the condenser for injection into the third acid line.
  • the third acid line can be equipped with a pump to provide the pressure required for injection.
  • a process-related pressure drop can be utilized. It is advantageous to use existing pumps such as acid condensate pumps, product acid pumps, filling pumps or trickle acid pumps, which already generate such a pressure drop.
  • the condenser has at least one nozzle. The nozzle is connected to the third acid line. The nozzle thus represents the connection between the third acid line and the interior of the condenser. Introduction into the condenser is particularly preferred because liquid is separated there anyway, i.e., ideal conditions exist in terms of temperature, and the liquid, the diluted nitric acid, is collected anyway and transferred to the absorption tower. This does not require any additional equipment.
  • the third connection has at least one nozzle.
  • the nozzle is connected to the third acid line.
  • nitric acid can be sprayed into the third connection from the third acid line.
  • the condenser has a NO side. Since the condenser is usually designed as a heat exchanger, it usually has, in addition to the NO side, a heat exchange medium side, on which, for example, cooling water flows and cools the NO x gas mixture to such an extent that condensation occurs. At the same time, the condensation heat can thus be easily and efficiently dissipated.
  • the NO side has a condenser gas inlet and a condenser gas outlet.
  • the condenser gas inlet is connected to the second connection, via which the NO x gas mixture is supplied.
  • the condenser gas outlet is connected to the third connection. Thus, condensation takes place between the condenser gas inlet and the condenser gas outlet.
  • the NO side has at least a first region with an upward gas flow and a second region with a downward gas flow.
  • the first region is arranged upstream of the second region in the flow direction.
  • the condenser can have several successive regions with alternating upward and downward gas flow.
  • upward and downward flow are arranged against and with gravity, respectively.
  • the nozzle is arranged above the first region with upward flow.
  • the condenser is designed as a cross-flow heat exchanger, in which the heat exchange medium, specifically cooling water, flows horizontally, while the gas flow alternates upwards and downwards, perpendicular to the heat exchange medium.
  • the heat exchange medium specifically cooling water
  • the multiple changes of direction enable effective heat exchange.
  • the condenser has a first part and a second part.
  • the condenser is constructed with mirror symmetry with respect to the NO side.
  • the condenser gas inlet is arranged centrally.
  • the first part preferably has the condenser gas outlet
  • the second part has a further condenser gas outlet.
  • the condenser gas outlet and the further condenser gas outlet are connected to the absorption tower via a Y-shaped third connection. This allows the contact area and thus the heat transfer in the condenser to be increased in a simple design.
  • the mirror symmetrical design means that in the first part and in the second part, the saltpeter side is sprayed into an upwardly directed gas stream.
  • the invention relates to a process for producing nitric acid by the indentation process.
  • the indentation process comprises the following steps: a) oxidation of ammonia with oxygen, b) Cooling of the oxidation product c) Condensation of the oxidation product in a condenser, d) Absorption to nitric acid in an absorption tower.
  • nitric acid produced in step c) or step d) is recycled, in particular sprayed, into the gas stream of the oxidation product in step c) and/or between steps c) and d).
  • nitric acid ensures an acidic environment, which favors the formation of ammonium nitrate over ammonium nitrite and thus reduces the safety risk. Spraying achieves optimal contact between the recycled liquid phase and the gas phase.
  • a liquid phase is separated after spraying.
  • the method is applied only temporarily, for example, only at certain time intervals, for example, every four hours for five minutes. This minimizes the effort involved.
  • the method according to the invention is carried out during the start-up of a device according to the invention until the catalyst has reached its operating temperature of, for example, over 700 °C.
  • the ammonia concentration in the oxidation product is additionally detected via a sensor, and the process is carried out if a predetermined ammonia concentration, which is preferably just above the detection limit, is exceeded.
  • a predetermined ammonia concentration which is preferably just above the detection limit
  • Fig. 1 shows a first exemplary device according to the invention in a highly schematic and simplified manner.
  • the heat exchange streams were not shown in the illustration, as this creates highly intersecting material streams and is irrelevant to the actual invention, as well as being known to those skilled in the art. Compression stages and the expansion of the product gas are also not shown for these reasons.
  • the illustration serves only to place the invention in the context of a device known to those skilled in the art for producing nitric acid from ammonia.
  • Essential to the invention is a third acid line 53, which returns nitric acid from the second acid outlet 67 of the absorption tower 30 to the condenser 20. This allows ammonia, which is not oxidized, to be has passed through the oxidation reactor, bound as ammonium nitrate and thus reliably removed from the gas stream.
  • Fig. 2 shows an exemplary and preferred condenser 20 in cross-section of the NO side.
  • the condenser 20 is constructed symmetrically with respect to the NO side, meaning that a condenser gas inlet 71 is arranged in the center, through which the NO x gas mixture coming from the second connection 42 is fed.
  • a condenser gas outlet 72 is arranged on the right and left, through which the NO x gas mixture is fed to the third connection 43.
  • the condenser 20 has a first acid outlet 61 on the underside, through which the diluted nitric acid is fed to the absorption tower 30 via the first acid line 51.

Landscapes

  • Chemical & Material Sciences (AREA)
  • Organic Chemistry (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Inorganic Chemistry (AREA)
  • Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)

Abstract

La présente invention concerne un dispositif de production d'acide nitrique à partir d'ammoniac, le dispositif comprenant un premier réacteur d'oxydation (10), au moins un premier échangeur de chaleur (12), un condenseur (20) et une tour d'absorption (30) ; le réacteur d'oxydation (10) est relié audit au moins un premier échangeur de chaleur (12) par l'intermédiaire d'une première liaison (41) pour le transfert du mélange gazeux de NOx ; ledit au moins un premier échangeur de chaleur (12) est relié au condenseur (20) par l'intermédiaire d'une deuxième liaison (42) pour le transfert du mélange gazeux de NOx ; le condenseur (20) est relié à la tour d'absorption (30) par l'intermédiaire d'une troisième liaison (43) pour le transfert du mélange gazeux de NOx ; le condenseur (20) a une première sortie d'acide ; la première sortie d'acide est reliée à une première entrée d'acide de la tour d'absorption (30) par l'intermédiaire d'une première conduite de circulation d'acide (51) ; la tour d'absorption (30) a une seconde sortie d'acide ; et la seconde sortie d'acide est reliée à une sortie de produit (36) par l'intermédiaire d'une deuxième conduite de circulation d'acide (52) ; caractérisée en ce que la première sortie d'acide ou la seconde sortie d'acide est reliée au condenseur (20) et/ou à la troisième liaison (43) par l'intermédiaire d'une troisième conduite de circulation d'acide (53).
PCT/EP2025/058975 2024-04-04 2025-04-02 Production sûre d'acide nitrique selon le procédé à pression unique Pending WO2025210081A1 (fr)

Applications Claiming Priority (4)

Application Number Priority Date Filing Date Title
LULU103274 2024-04-04
DE102024109405.2A DE102024109405A1 (de) 2024-04-04 2024-04-04 Sichere Herstellung von Salpetersäure nach dem Eindruckverfahren
LU103274A LU103274B1 (de) 2024-04-04 2024-04-04 Sichere Herstellung von Salpetersäure nach dem Eindruckverfahren
DE102024109405.2 2024-04-04

Publications (1)

Publication Number Publication Date
WO2025210081A1 true WO2025210081A1 (fr) 2025-10-09

Family

ID=95290316

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/EP2025/058975 Pending WO2025210081A1 (fr) 2024-04-04 2025-04-02 Production sûre d'acide nitrique selon le procédé à pression unique

Country Status (1)

Country Link
WO (1) WO2025210081A1 (fr)

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4276277A (en) 1970-06-12 1981-06-30 Produits Chimiques Ugine Kuhlmann Manufacture of concentrated nitric acid
US5985230A (en) 1996-10-03 1999-11-16 L'air Liquide, Societe Anonyme Pour L'etude Et L'exploitation Des Procedes Georges Claude Nitric acid production
US7118723B2 (en) 2000-03-10 2006-10-10 Uhde Gmbh Method for producing nitric acid
DE102017201180A1 (de) 2017-01-25 2018-07-26 Thyssenkrupp Ag Verfahren zur Herstellung von Salpetersäure und dafür geeignete Anlage

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4276277A (en) 1970-06-12 1981-06-30 Produits Chimiques Ugine Kuhlmann Manufacture of concentrated nitric acid
US5985230A (en) 1996-10-03 1999-11-16 L'air Liquide, Societe Anonyme Pour L'etude Et L'exploitation Des Procedes Georges Claude Nitric acid production
US7118723B2 (en) 2000-03-10 2006-10-10 Uhde Gmbh Method for producing nitric acid
DE102017201180A1 (de) 2017-01-25 2018-07-26 Thyssenkrupp Ag Verfahren zur Herstellung von Salpetersäure und dafür geeignete Anlage

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