EP1144104A1 - Method and device for producing formaldehyde - Google Patents

Method and device for producing formaldehyde

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Publication number
EP1144104A1
EP1144104A1 EP99957687A EP99957687A EP1144104A1 EP 1144104 A1 EP1144104 A1 EP 1144104A1 EP 99957687 A EP99957687 A EP 99957687A EP 99957687 A EP99957687 A EP 99957687A EP 1144104 A1 EP1144104 A1 EP 1144104A1
Authority
EP
European Patent Office
Prior art keywords
reaction gas
cooler
cooled
formaldehyde
reactor
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.)
Ceased
Application number
EP99957687A
Other languages
German (de)
French (fr)
Inventor
Wladimir Linzer
Thomas Schmid
Ralph Peter Theuer
Josef Schreiber
Wilfried Bauer
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.)
Krems Chemie GmbH
Original Assignee
Krems Chemie GmbH
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Filing date
Publication date
Application filed by Krems Chemie GmbH filed Critical Krems Chemie GmbH
Publication of EP1144104A1 publication Critical patent/EP1144104A1/en
Ceased legal-status Critical Current

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Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J8/00—Chemical or physical processes in general, conducted in the presence of fluids and solid particles; Apparatus for such processes
    • B01J8/02—Chemical or physical processes in general, conducted in the presence of fluids and solid particles; Apparatus for such processes with stationary particles, e.g. in fixed beds
    • B01J8/0285—Heating or cooling the reactor
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J8/00—Chemical or physical processes in general, conducted in the presence of fluids and solid particles; Apparatus for such processes
    • B01J8/02—Chemical or physical processes in general, conducted in the presence of fluids and solid particles; Apparatus for such processes with stationary particles, e.g. in fixed beds
    • B01J8/0242—Chemical or physical processes in general, conducted in the presence of fluids and solid particles; Apparatus for such processes with stationary particles, e.g. in fixed beds the fluid flow within the bed being predominantly vertical
    • B01J8/025—Chemical or physical processes in general, conducted in the presence of fluids and solid particles; Apparatus for such processes with stationary particles, e.g. in fixed beds the fluid flow within the bed being predominantly vertical in a cylindrical shaped bed
    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
    • C07C45/00—Preparation of compounds having >C = O groups bound only to carbon or hydrogen atoms; Preparation of chelates of such compounds
    • C07C45/27—Preparation of compounds having >C = O groups bound only to carbon or hydrogen atoms; Preparation of chelates of such compounds by oxidation
    • C07C45/32—Preparation of compounds having >C = O groups bound only to carbon or hydrogen atoms; Preparation of chelates of such compounds by oxidation with molecular oxygen
    • C07C45/37—Preparation of compounds having >C = O groups bound only to carbon or hydrogen atoms; Preparation of chelates of such compounds by oxidation with molecular oxygen of >C—O—functional groups to >C=O groups
    • C07C45/38—Preparation of compounds having >C = O groups bound only to carbon or hydrogen atoms; Preparation of chelates of such compounds by oxidation with molecular oxygen of >C—O—functional groups to >C=O groups being a primary hydroxyl group
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J2208/00—Processes carried out in the presence of solid particles; Reactors therefor
    • B01J2208/00008—Controlling the process
    • B01J2208/00017—Controlling the temperature
    • B01J2208/00106—Controlling the temperature by indirect heat exchange
    • B01J2208/00168—Controlling the temperature by indirect heat exchange with heat exchange elements outside the bed of solid particles
    • B01J2208/00194—Tubes
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J2208/00—Processes carried out in the presence of solid particles; Reactors therefor
    • B01J2208/00008—Controlling the process
    • B01J2208/00017—Controlling the temperature
    • B01J2208/00106—Controlling the temperature by indirect heat exchange
    • B01J2208/00168—Controlling the temperature by indirect heat exchange with heat exchange elements outside the bed of solid particles
    • B01J2208/00203—Coils
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J2208/00—Processes carried out in the presence of solid particles; Reactors therefor
    • B01J2208/00008—Controlling the process
    • B01J2208/00017—Controlling the temperature
    • B01J2208/00106—Controlling the temperature by indirect heat exchange
    • B01J2208/00168—Controlling the temperature by indirect heat exchange with heat exchange elements outside the bed of solid particles
    • B01J2208/00256—Controlling the temperature by indirect heat exchange with heat exchange elements outside the bed of solid particles in a heat exchanger for the heat exchange medium separate from the reactor

Definitions

  • the present invention relates to a process for the production of formaldehyde from air, methanol and optionally water.
  • the exothermic reaction is carried out in a special device on a silver catalyst.
  • the hot reaction gases are generated in a specially designed heat exchanger package in less than 60 msec. cooled to below 300 ° C. Further cooling takes place via additional heat exchanger surfaces and / or by injecting a cooled formaldehyde solution.
  • a slightly inclined tube bundle apparatus in which the vapor bubbles can escape faster due to the inclination.
  • the catalyst that is inclined at the same time is more difficult to insert and can easily slip, especially in the initial phase in the case of vapor bubble vibrations, which can lead to considerable reductions in yield or require a restart.
  • these known constructions require a cooling time which is far too long, which means that additional losses in yield and poor product quality have to be accepted.
  • US Pat. No. 4,358,623 it is proposed to fill the balls on the gas side with inert balls in order to shorten the residence time.
  • a porous plate between the perforated plate and the catalyst is recommended to eliminate the above defect.
  • German laid-open specification 25 46 104 describes a reactor which uses a tube bundle apparatus for cooling the reaction gases and through which the cooling medium flows on the tube side.
  • the apparatus is inclined at an angle, preferably rectangular, and supplied with cooling medium via external collectors.
  • Collectors and rectangular designs welded to the housing lead to pressure and thermal stress problems both on the reaction gas side and on the steam side.
  • the thermal stresses and the rectangular construction easily lead to sealing problems, so that there is a risk of escaping from methanol vapors or formaldehyde gas.
  • German Offenlegungsschrift 20 02 789 a reaction gas cooler is described, which is arranged directly under the catalyst bed, serves as a catalyst carrier and consists of elongated, multi-wound snakes.
  • a reaction gas cooler which is arranged directly under the catalyst bed, serves as a catalyst carrier and consists of elongated, multi-wound snakes.
  • rectangular designs are preferred and compartments are made in order to increase reaction gas speeds and shorten cooling times.
  • the rectangular design tion has the disadvantages known in pressure vessels and already mentioned above. A division into chambers is difficult to manufacture and difficult to clean.
  • the object of the invention is to provide a method and a device for producing formaldehyde by means of a new reaction gas cooler construction, as a result of which the reaction gas is produced in less than 60 msec. , preferably less than 30 msec., is cooled and high yields, good product qualities and problem-free apparatus life are ensured.
  • reaction gas in the formaldehyde reactor with an internally cooled horizontal tube heat exchanger in less than 60 msec. is cooled from 550-700 ° C to below 300 ° C. If necessary, the cooled reaction gas can then be further cooled in a spray cooler to a temperature of approximately 80 ° C., for example by injecting a formalin product solution or a mixture of formalin product and water.
  • a tube bundle with horizontal tubes is used for heat dissipation or for steam generation, in which boiling water is circulated on the tube side and the steam quench is separated from the water in a steam drum. The steam is released to the consumers, and the water is returned to the tube bundle apparatus via a circulation pump.
  • the design of the boiler essentially corresponds to that of a water tube boiler.
  • the unusual thing about this reaction gas cooler is that, due to the round design of the reactor, the evaporator tubes are not of the same length and are arranged horizontally.
  • the pipes are preferably equipped with throttles individually or in groups.
  • the reaction gas cooler designed according to the invention enables the generation of high pressure steam with a pressure of up to 40 bar.
  • the arrangement of throttles on the evaporator tubes stabilizes the flow rate of the cooling medium in the tubes, thereby making tube sections of different lengths possible, which lead to formaldehyde reactor shapes other than rectangular designs, preferably cylindrical reactors.
  • the tube bundle apparatus can be kept vibration-free by arranging tube support rings around the cooling tubes and additional support rings on the reactor wall.
  • the tube bundle serves as a support for the catalyst carrier.
  • the catalyst carrier expediently rests on the uppermost layer of the cooling tubes, as a result of which an uncooled gas space between the catalyst carrier and cooling tubes is avoided and rapid and efficient cooling of the hot reaction gases is ensured.
  • a very low carbon monoxide content of typically less than 0.1% by volume can be achieved in the cooled reaction gas, even if the catalyst temperature is above 680 ° C. If, according to a preferred embodiment, the horizontal tube heat exchanger according to the invention is combined with a spray cooler for the cooled reaction gas, the carbon monoxide content in the cooled reaction gas can be reduced to values of typically 0.05% by volume.
  • the gaseous starting materials enter the reactor at the gas inlet port 1 and react in the catalyst bed 2 to form a reaction gas containing about 680 ° C. which, after cooling in the tube bundle reaction gas cooler 3 and further cooling by a spray cooler 4 fed with formaldehyde solution, the reactor through the gas outlet port 5 leaves.
  • the cooling water flows from the steam drum 6 to the circulation pump 7 and passes through the throttles 8 into the lowest horizontal tube set of the tube bundle reaction gas cooler 3 and emerges from the topmost one, arranged directly under the catalyst bed 2. Neten coulter from the reactor and gets into the
  • the steam is drawn off from the steam drum 6 via a steam outlet 9 for further use, the amount of cooling water is supplemented to the required extent via a cooling water inlet 10.
  • the invention is illustrated by the following example.
  • 18,480 kg of starting mixture are passed through the reactor every hour.
  • the gas mixture After distribution in the upper reactor space, the gas mixture passes through the bed of catalyst silver 2 and the tube bundle gas cooler 3 located immediately below it.
  • the starting materials When passing through the catalyst bed 2, the starting materials react to form hydrogen or water to formaldehyde.
  • formaldehyde typically, 4,625 kg / h formaldehyde, 127.5 kg / h H, 610 kg / h CO + CO2 are produced from 18,480 kg / h starting mixture, the rest consists of nitrogen, water vapor and residual methanol. Since it is an exothermic reaction overall, a temperature of 680 ° C occurs on the catalyst bed.
  • reaction mixture passes immediately after the catalyst through the reaction gas cooler 3, which has already been described in more detail, and is cooled to about 280.degree.
  • the boiling boiler water emerges from the higher-lying steam drum 6 and is pumped to the reaction cooler 3 by pumps 7 on the ground floor in forced circulation through distributor 8.
  • the steam / water mixture that forms in the heated cooler tubes has a steam content of 10% by weight and leaves the cooler via a header tube and associated riser Lines to the steam drum 6.
  • the steam separated from the water leaves the drum through a shut-off valve in the steam line 9.
  • the steam production is 4,780 kg / h under the specified operating conditions.
  • the saturated steam generated has a pressure of 10 bar gauge pressure and a temperature of 184 ° C.
  • the amount of steam generated is supplemented by adding feed water via the feed water line 10.
  • reaction mixture After cooling to 280 ° C., the reaction mixture is cooled further to about 95 ° C. by injecting a cooled formalin solution 4.
  • the gas mixture finally leaves the reactor through the outlet connection 5 and is fed to the other parts of the plant.

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

Abstract

The invention relates to a method for producing formaldehyde from air, methanol and possibly water in a formaldehyde reactor with silver catalyst (2). By means of a special reaction gas cooling structure (3) the reaction gas is cooled in less than 60 milliseconds. The reaction gas cooler is configured as an internally-cooled horizontal tube heat exchanger (3). A spray cooler (4) can be arranged below the reaction gas cooler (3). The method provided for in the invention allows for high yields, good product quality and a trouble-free service life of the apparatus.

Description

Verfahren und Vorrichtung zur Herstellung von Formaldehyd V f Ahren he and apparatus for the production of formaldehyde
Die vorliegende Erfindung bezieht sich auf ein Verfahren zur Herstellung von Formaldehyd aus Luft, Methanol und gegebenenfalls Wasser. Die exotherme Reaktion wird in einer speziellen Vorrichtung an einem Silberkatalysator ausgeführt. Die heißen Reaktionsgase werden hiebei in einem speziell ausgebildeten Wärmetauscherpaket in weniger als 60 msek. auf unter 300°C abgekühlt. Die weitere Abkühlung erfolgt über zusätzliche Wärmetauscherflächen und/oder durch Einspritzen einer gekühlten For- aldehydlösung .The present invention relates to a process for the production of formaldehyde from air, methanol and optionally water. The exothermic reaction is carried out in a special device on a silver catalyst. The hot reaction gases are generated in a specially designed heat exchanger package in less than 60 msec. cooled to below 300 ° C. Further cooling takes place via additional heat exchanger surfaces and / or by injecting a cooled formaldehyde solution.
Beim Formalinverfahren mit Silberkatalysatoren (oxidierende Dehydrierung von Methanol) ist es üblich und bekannt, die Reaktionswärme über einen Wärmetauscher abzuführen und in Form von Dampf, Heißwasser oder Wärmeträgeröl weiter zu nutzen. Um Neben- und Zerfallsreaktionen zu vermeiden, muß die Abkühlung der 550-700°C heißen Reaktionsgase möglichst rasch erfolgen. Die am häufigsten eingesetzte Konstruktionsform ist ein stehender Rohrbündelapparat, bei dem oben auf der Lochplatte der Katalysator aufliegt. Diese Bauform hat den Nachteil, daß die obere Lochplatte durch Dampfblasen schlecht gekühlt wird und daher thermisch hoch belastet ist. Apparateschäden und Rußablagerungen sind die Folge. Frühere Vorschläge, wie das tschechische Patent CS-224017, das ein Zwischensieb auf der Lochplatte vorsieht, oder das DDR-Patent DD-249473, welches eine gekühlte Dichtung vorschlägt, versuchen mit eingeschränktem Erfolg, diesen Mißstand zu beheben.In the formalin process using silver catalysts (oxidizing dehydrogenation of methanol), it is customary and known to remove the heat of reaction via a heat exchanger and to use it further in the form of steam, hot water or heat transfer oil. In order to avoid side and decomposition reactions, the cooling of the 550-700 ° C reaction gases must take place as quickly as possible. The most common design is a vertical tube bundle with the catalyst resting on top of the perforated plate. This design has the disadvantage that the upper perforated plate is poorly cooled by steam bubbles and is therefore highly thermally stressed. Damage to the apparatus and soot deposits are the result. Previous proposals, such as the Czech patent CS-224017, which provides an intermediate sieve on the perforated plate, or the GDR patent DD-249473, which proposes a cooled seal, attempt to remedy this problem with limited success.
Als weitere technische Variante ist ein leicht schräg geneigter Rohrbündelapparat bekannt, bei dem infolge der Neigung die Dampfbläschen schneller entweichen können. Der dadurch gleichzeitig schräg liegende Katalysator ist schwerer einzubringen und kann vor allem in der Anfangsphase bei Dampfbläschenvibrationen leicht verrutschen, was zu erheblichen Ausbeuteverminderungen führen kann bzw. einen Neustart erfordert. Weiterhin bedingen diese bekannten Konstruktionen eine viel zu lange Abkühlzeit, wodurch zusätzliche Ausbeuteverluste und mangelnde Produktqualität in Kauf genommen werden müssen. Im US- Patent 4358623 wird vorgeschlagen, in die Rohre gasseitig Inertkugeln einzufüllen, um die Verweilzeit zu verkürzen. Im tschechischen Patent CS-227155 wird zur Beseitigung des vorstehenden Mangels eine poröse Platte zwischen Lochplatte und Katalysator empfohlen.As a further technical variant, a slightly inclined tube bundle apparatus is known, in which the vapor bubbles can escape faster due to the inclination. The catalyst that is inclined at the same time is more difficult to insert and can easily slip, especially in the initial phase in the case of vapor bubble vibrations, which can lead to considerable reductions in yield or require a restart. Furthermore, these known constructions require a cooling time which is far too long, which means that additional losses in yield and poor product quality have to be accepted. In US Pat. No. 4,358,623 it is proposed to fill the balls on the gas side with inert balls in order to shorten the residence time. In the Czech patent CS-227155, a porous plate between the perforated plate and the catalyst is recommended to eliminate the above defect.
Allen vorstehend erwähnten Konstruktionen haftet nach wie vor der Nachteil an, daß nur unbefriedigend lange Abkühlzeiten von einigen Zehntelsekunden erreicht werden, bei gleichzeitig hohen erforderlichen Katalysatorbelastungen. Ein weiterer Nachteil dieser Konstruktionen liegt darin, daß die Apparate infolge der relativ schlechten Wärmeübergangskoeffizienten verhältnismäßig groß, schwer und teuer sind. Soll die Abwärme in Form von Dampf genutzt werden, so sind aus Festigkeitsgründen nur relativ niedrige Sattdampfdrücke von wenigen bar möglich.All of the above-mentioned constructions still have the disadvantage that unsatisfactorily long cooling times of a few tenths of a second are achieved, with high catalyst loads being required at the same time. Another disadvantage of these designs is that the apparatus are relatively large, heavy and expensive due to the relatively poor heat transfer coefficients. If the waste heat is to be used in the form of steam, only relatively low saturated steam pressures of a few bar are possible for reasons of strength.
In der deutschen Offenlegungsschrift 25 46 104 wird ein Reaktor beschrieben, der zur Abkühlung der Reaktionsgase einen Rohrbündelapparat verwendet, der rohrseitig vom Kühlmedium durchströmt wird. Um instabile Strömungsverhältnisse im Rohrbündel zu vermeiden, wird der Apparat schräg geneigt, vorzugsweise rechteckig ausgeführt und über außenliegende Sammler mit Kühlmedium versorgt. Der Nachteil der schrägen Anordnung wurde bereits oben dargestellt. Am Gehäuse angeschweißte Sammler und rechteckige Ausführungen führen sowohl reaktionsgasseitig als auch dampfseitig zu Druck- und Wärmespannungsproblemen. Weiterhin führen die WärmeSpannungen und die rechteckige Konstruktion leicht zu Dichtungsproblemen, sodaß die Gefahr eines Entwei- chens von Methanoldämpfen oder Formaldehydgas gegeben ist.German laid-open specification 25 46 104 describes a reactor which uses a tube bundle apparatus for cooling the reaction gases and through which the cooling medium flows on the tube side. In order to avoid unstable flow conditions in the tube bundle, the apparatus is inclined at an angle, preferably rectangular, and supplied with cooling medium via external collectors. The disadvantage of the oblique arrangement has already been shown above. Collectors and rectangular designs welded to the housing lead to pressure and thermal stress problems both on the reaction gas side and on the steam side. Furthermore, the thermal stresses and the rectangular construction easily lead to sealing problems, so that there is a risk of escaping from methanol vapors or formaldehyde gas.
Schließlich wird in der deutschen Offenlegungsschrift 20 02 789 ein Reaktionsgaskühler beschrieben, der direkt unter dem Katalysatorbett angeordnet ist, als Katalysatorträger dient und aus langgestreckten, mehrfach gewundenen Schlangen besteht. Auch hier werden rechteckige Ausführungen bevorzugt und Unterteilungen in Kammern vorgenommen, um Reaktionsgasgeschwindigkeiten zu erhöhen und Abkühlzeiten zu verkürzen. Die rechteckige Ausfüh- rung hat die bei Druckbehältern bekannten und oben bereits erwähnten Nachteile. Eine Unterteilung in Kammern ist schwierig zu fertigen und schwer zu reinigen.Finally, in German Offenlegungsschrift 20 02 789 a reaction gas cooler is described, which is arranged directly under the catalyst bed, serves as a catalyst carrier and consists of elongated, multi-wound snakes. Here, too, rectangular designs are preferred and compartments are made in order to increase reaction gas speeds and shorten cooling times. The rectangular design tion has the disadvantages known in pressure vessels and already mentioned above. A division into chambers is difficult to manufacture and difficult to clean.
Der Erfindung liegt die Aufgabe zugrunde, durch eine neue Reak- tionsgas-Kühlerkonstruktion ein Verfahren und eine Vorrichtung zur Herstellung von Formaldehyd zur Verfügung zu stellen, wodurch das Reaktionsgas in weniger als 60 msek. , bevorzugt weniger als 30 msek., abgekühlt wird und hohe Ausbeuten, gute Pro- duktqualitäten und problemlose Apparatestandzeiten sichergestellt werden.The object of the invention is to provide a method and a device for producing formaldehyde by means of a new reaction gas cooler construction, as a result of which the reaction gas is produced in less than 60 msec. , preferably less than 30 msec., is cooled and high yields, good product qualities and problem-free apparatus life are ensured.
Diese Aufgabe wird erfindungsgemäß dadurch gelöst, daß das Reaktionsgas im Formaldehydreaktor mit einem innengekühlten Horizontal-Rohrwärmetauscher in weniger als 60 msek. von 550- 700°C auf unter 300°C abgekühlt wird. Gegebenenfalls kann das abgekühlte Reaktionsgas anschließend in einem Sprühkühler weiter auf eine Temperatur von etwa 80 °C abgekühlt werden, beispielsweise durch Einspritzen einer Formalinproduktlösung oder eines Gemisches aus Formalinprodukt und Wasser.This object is achieved in that the reaction gas in the formaldehyde reactor with an internally cooled horizontal tube heat exchanger in less than 60 msec. is cooled from 550-700 ° C to below 300 ° C. If necessary, the cooled reaction gas can then be further cooled in a spray cooler to a temperature of approximately 80 ° C., for example by injecting a formalin product solution or a mixture of formalin product and water.
Im erfindungsgemäß ausgestalteten Reaktionsgaskühler wird zur Wärmeabfuhr bzw. zur Dampferzeugung ein Rohrbündelapparat mit waagrechten Rohren eingesetzt, in dem rohrseitig Siedewasser zirkuliert und in einer Dampftrommel die Dampf läschen vom Wasser getrennt werden. Der Dampf wird zu den Verbrauchern abgegeben, das Wasser wird über eine Umlaufpumpe wieder dem Rohrbündelapparat zugeführt. Die Bauart des Kessels entspricht im wesentlichen derjenigen eines Wasserrohrkessels. Das ungewöhnliche an diesem Reaktionsgaskühler ist, daß die Verdampferrohre, bedingt durch die runde Bauart des Reaktors, ungleich lang und waagrecht angeordnet sind. Um ein Verbiegen der Rohre und eine ungleichmäßige Wasserbeaufschlagung zu verhindern, werden die Rohre vorzugsweise einzeln oder in Gruppen mit Drosseln ausgestattet . Weiterhin sind die Rohrdurchtritte durch das Gehäuse in vorteilhafter Weise so knapp gesetzt, daß Dehnhülsen entfallen können und trotzdem die WärmeSpannungen im zulässigen Bereich bleiben. Vorteilhaft sind die Abstände der Rohre untereinander so knapp gesetzt, daß sie erst nach mindestens einer internen Umleitung wieder nach außen geleitet werden können. Der erfindungsgemäß ausgestaltete Reaktionsgaskühler ermöglicht die Erzeugung von Hochdruckdampf mit bis zu 40 bar Druck. Durch die Anordnung von Drosseln an den Verdampferröhren wird die Strömungsgeschwindigkeit des Kühlmediums in den Rohren stabilisiert, wodurch unterschiedlich lange beheizte Rohrabschnitte ermöglicht werden, die zu anderen Formaldehydreaktorformen als rechteckige Ausführungen führen, vorzugsweise zu zylindrischen Reaktoren. Durch eine Anordnung von Rohrstützringen um die Kühlrohre und durch zusätzliche Stützringe an der Reaktorwand kann der Rohrbündelapparat vibrationsfrei gehalten werden. Darüber hinaus dient das Rohrbündel als Auflage für den Katalysatorträger. Der Katalysatorträger liegt zweckmäßig auf der obersten Lage der Kühlrohre auf, wodurch ein ungekühlter Gas- raum zwischen Katalysatorträger und Kühlrohren vermieden und ein rasches und effizientes Abkühlen der heißen Reaktionsgase sichergestellt wird.In the reaction gas cooler designed according to the invention, a tube bundle with horizontal tubes is used for heat dissipation or for steam generation, in which boiling water is circulated on the tube side and the steam quench is separated from the water in a steam drum. The steam is released to the consumers, and the water is returned to the tube bundle apparatus via a circulation pump. The design of the boiler essentially corresponds to that of a water tube boiler. The unusual thing about this reaction gas cooler is that, due to the round design of the reactor, the evaporator tubes are not of the same length and are arranged horizontally. In order to prevent the pipes from bending and uneven exposure to water, the pipes are preferably equipped with throttles individually or in groups. Furthermore, the pipe penetrations through the housing are advantageously set so tight that expansion sleeves can be omitted and the thermal stresses remain within the permissible range. The distances between the pipes are advantageously set so close that they can only be led outside again after at least one internal diversion. The reaction gas cooler designed according to the invention enables the generation of high pressure steam with a pressure of up to 40 bar. The arrangement of throttles on the evaporator tubes stabilizes the flow rate of the cooling medium in the tubes, thereby making tube sections of different lengths possible, which lead to formaldehyde reactor shapes other than rectangular designs, preferably cylindrical reactors. The tube bundle apparatus can be kept vibration-free by arranging tube support rings around the cooling tubes and additional support rings on the reactor wall. In addition, the tube bundle serves as a support for the catalyst carrier. The catalyst carrier expediently rests on the uppermost layer of the cooling tubes, as a result of which an uncooled gas space between the catalyst carrier and cooling tubes is avoided and rapid and efficient cooling of the hot reaction gases is ensured.
Mit der erfindungsgemäßen Verfahrensführung kann im gekühlten Reaktionsgas ein sehr niedriger Kohlenmonoxidgehalt von typisch unter 0,1 Vol.-% erreicht werden, selbst wenn die Katalysatortemperatur über 680°C liegt. Wird gemäß einer bevorzugten Ausführungsform der erfindungsgemäße Horizontal-Rohrwärmetauscher mit einem Sprühkühler für das abgekühlte Reaktionsgas kombiniert, so kann der Kohlenmonoxidgehalt auf Werte von typisch 0,05 Vol.-% im abgekühlten Reaktionsgas erniedrigt werden.With the process control according to the invention, a very low carbon monoxide content of typically less than 0.1% by volume can be achieved in the cooled reaction gas, even if the catalyst temperature is above 680 ° C. If, according to a preferred embodiment, the horizontal tube heat exchanger according to the invention is combined with a spray cooler for the cooled reaction gas, the carbon monoxide content in the cooled reaction gas can be reduced to values of typically 0.05% by volume.
In der angeschlossenen Zeichnung ist eine bevorzugte Ausführungsform der Erfindung schematisch dargestellt.A preferred embodiment of the invention is shown schematically in the attached drawing.
Die gasförmigen Ausgangsstoffe treten am Gaseintrittsstutzen 1 in den Reaktor ein und reagieren im Katalysatorbett 2 zu einem ca. 680°C heißen formaldehydhaltigen Reaktionsgas, das nach Kühlung im Rohrbündel-Reaktionsgaskühler 3 und weiterer Abkühlung durch einen mit Formaldehydlösung gespeisten Sprühkühler 4 den Reaktor durch den Gasaustrittsstutzen 5 verläßt.The gaseous starting materials enter the reactor at the gas inlet port 1 and react in the catalyst bed 2 to form a reaction gas containing about 680 ° C. which, after cooling in the tube bundle reaction gas cooler 3 and further cooling by a spray cooler 4 fed with formaldehyde solution, the reactor through the gas outlet port 5 leaves.
Das Kühlwasser fließt aus der Dampftrommel 6 zur Umlaufpumpe 7 und gelangt durch die Drosseln 8 in die unterste waagrechte Rohrschar des Rohrbündel-Reaktionsgaskühlers 3 und tritt aus der obersten, unmittelbar unter dem Katalysatorbett 2 angeord- neten Rohrschar wieder aus dem Reaktor aus und gelangt in dieThe cooling water flows from the steam drum 6 to the circulation pump 7 and passes through the throttles 8 into the lowest horizontal tube set of the tube bundle reaction gas cooler 3 and emerges from the topmost one, arranged directly under the catalyst bed 2. Neten coulter from the reactor and gets into the
Dampftrommel 6.Steam drum 6.
Der Dampf wird über einen Dampfaustritt 9 zur weiteren Verwendung aus der Dampftrommel 6 abgezogen, die Kühlwassermenge wird im erforderlichen Ausmaß über einen Kühlwasserzulauf 10 ergänzt.The steam is drawn off from the steam drum 6 via a steam outlet 9 for further use, the amount of cooling water is supplemented to the required extent via a cooling water inlet 10.
Die Erfindung wird durch das nachfolgende Beispiel weiter erläutert.The invention is illustrated by the following example.
Beispiel :For example:
Die Ausgangsstoffe Methanol, Wasser und Luft treten im gas- bzw. dampfförmigen Zustand durch den Eintrittsstutzen 1 in den Reaktor ein. Für eine Produktion von 100.000 Tonnen/Jahr 37 igem Formalin werden stündlich 18.480 kg Ausgangsgemisch durch den Reaktor geleitet .The starting materials methanol, water and air enter the reactor in the gaseous or vaporous state through the inlet connection 1. For a production of 100,000 tons / year of 37 formalin, 18,480 kg of starting mixture are passed through the reactor every hour.
Nach Verteilung im oberen Reaktorraum tritt das Gasgemisch durch die Schüttung aus Katalysatorsilber 2 und den unmittelbar darunter liegenden Rohrbündel-Gaskühler 3 hindurch.After distribution in the upper reactor space, the gas mixture passes through the bed of catalyst silver 2 and the tube bundle gas cooler 3 located immediately below it.
Beim Passieren des Katalysatorbettes 2 reagieren die Ausgangs- Stoffe unter Bildung von Wasserstoff bzw. Wasser zu Formaldehyd. Aus 18.480 kg/h Ausgangsgemisch entstehen dabei typischerweise 4.625 kg/h Formaldehyd, 127,5 kg/h H , 610 kg/h CO+CO2, der Rest besteht aus Stickstoff, Wasserdampf und Restmethanol. Da es sich insgesamt um eine exotherme Reaktion handelt, tritt am Katalysatorbett eine Temperatur von 680°C auf.When passing through the catalyst bed 2, the starting materials react to form hydrogen or water to formaldehyde. Typically, 4,625 kg / h formaldehyde, 127.5 kg / h H, 610 kg / h CO + CO2 are produced from 18,480 kg / h starting mixture, the rest consists of nitrogen, water vapor and residual methanol. Since it is an exothermic reaction overall, a temperature of 680 ° C occurs on the catalyst bed.
Um ein Weiterreagieren des entstandenen Formalins zu CO2 zu verhindern, passiert das Reaktionsgemisch unmittelbar nach dem Katalysator den bereits näher beschriebenen Reaktionsgaskühler 3 und wird dabei auf ca. 280°C abgekühlt.In order to prevent the resulting formalin from reacting further to CO2, the reaction mixture passes immediately after the catalyst through the reaction gas cooler 3, which has already been described in more detail, and is cooled to about 280.degree.
Das siedende Kesselwasser tritt aus der höher gelegenen Dampf- trommel 6 nach unten aus und wird durch im Erdgeschoß stehende Pumpen 7 im Zwangsumlauf durch Verteiler 8 dem Reaktionskühler 3 zugeführt. Das in den erhitzten Kühlerrohren entstehende Dampf/Wasser-Gemisch hat einen Dampfanteil von 10 Gew.-% und verläßt den Kühler über ein Sammelrohr und dazugehörige Steig- leitungen zur Dampftrommel 6. Der vom Wasser getrennte Dampf verläßt die Trommel durch ein Absperrventil in die Dampfleitung 9. Die DampfProduk ion beträgt bei den angegebenen Betriebsbedingungen 4.780 kg/h. Der erzeugte Sattdampf hat einen Druck von 10 bar Überdruck und eine Temperatur von 184°C. Die erzeugte Dampfmenge wird durch Speisewasserzugabe über die Speisewasserleitung 10 ergänzt.The boiling boiler water emerges from the higher-lying steam drum 6 and is pumped to the reaction cooler 3 by pumps 7 on the ground floor in forced circulation through distributor 8. The steam / water mixture that forms in the heated cooler tubes has a steam content of 10% by weight and leaves the cooler via a header tube and associated riser Lines to the steam drum 6. The steam separated from the water leaves the drum through a shut-off valve in the steam line 9. The steam production is 4,780 kg / h under the specified operating conditions. The saturated steam generated has a pressure of 10 bar gauge pressure and a temperature of 184 ° C. The amount of steam generated is supplemented by adding feed water via the feed water line 10.
Nach der Abkühlung auf 280°C wird das Reaktionsgemisch durch Einspritzen einer gekühlten Formalinlösung 4 weiter auf etwa 95°C gekühlt.After cooling to 280 ° C., the reaction mixture is cooled further to about 95 ° C. by injecting a cooled formalin solution 4.
Das Gasgemisch verläßt den Reaktor zuletzt durch den Austritts- stutzen 5 und wird den weiteren Anlagenteilen zugeführt. The gas mixture finally leaves the reactor through the outlet connection 5 and is fed to the other parts of the plant.

Claims

PATENTANSPRUCHEPATENT CLAIMS
Verfahren zur Herstellung von Formaldehyd aus Luft, Methanol und gegebenenfalls Wasser in einem Formaldehydreaktor an einem Silberkatalysator mit einem darunter liegenden Kühler mit Horizontalrohren, dadurch gekennzeichnet, daß das Reaktionsgas im Formaldehydreaktor mit einem innengekühlten Horizontalrohrwärmetauscher in weniger als 60 Millisekunden von 550-700°C auf unter 300°C abgekühlt wird.Process for the production of formaldehyde from air, methanol and optionally water in a formaldehyde reactor on a silver catalyst with an underlying cooler with horizontal tubes, characterized in that the reaction gas in the formaldehyde reactor with an internally cooled horizontal tube heat exchanger from 550-700 ° C in less than 60 milliseconds is cooled below 300 ° C.
Verfahren nach Anspruch 1, dadurch gekennzeichnet, daß das abgekühlte Reaktionsgas durch Einspritzen einer Formalin- produktlösung oder eines Gemisches aus Formalinprodukt und Wasser in einem Sprühkühler weiter auf eine Temperatur von etwa 80°C abgekühlt wird.A method according to claim 1, characterized in that the cooled reaction gas is further cooled to a temperature of about 80 ° C by injecting a formalin product solution or a mixture of formalin product and water in a spray cooler.
Vorrichtung zur Durchführung des Verfahrens nach Anspruch 1 oder 2, bestehend aus mit einem Gaseintrittsstutzen (1) für das Einsatzgemisch versehenen Kopfraum, dessen untere Begrenzung aus einem Katalysatorbett (2) besteht, unter dem sich ein Reaktionsgaskühler (3) mit Horizontalrohren sowie ein Gasaustrittsstutzen (5) für das abgekühlte for- maldehydhaltige Reaktionsgas befinden, dadurch gekennzeichnet, daß der Reaktionsgaskühler (3) als ein im Querschnitt runder, innengekühlter Horizontalrohrwärmetauscher mit vom Reaktionsgas beheizten, unterschiedlich langen Wärme auschrohren ausgestattet ist.Apparatus for carrying out the method according to claim 1 or 2, comprising a head space provided with a gas inlet connection (1) for the feed mixture, the lower boundary of which consists of a catalyst bed (2), under which there is a reaction gas cooler (3) with horizontal tubes and a gas outlet connection ( 5) for the cooled, formaldehyde-containing reaction gas, characterized in that the reaction gas cooler (3) is equipped as a round, internally cooled horizontal tube heat exchanger with a section of heat heated by the reaction gas and of different lengths.
Vorrichtung nach Anspruch 3, dadurch gekennzeichnet, daß im Bereich unterhalb des Reaktionsgaskühlers (3) ein Sprühkühler (4) angeordnet ist.Device according to claim 3, characterized in that a spray cooler (4) is arranged in the area below the reaction gas cooler (3).
Vorrichtung nach Anspruch 3 oder 4, dadurch gekennzeichnet, daß der den Katalysator aufnehmende Katalysatorträger auf der obersten Lage der Kühlrohre des Reaktionsgas- kühlers (3) aufliegt.Apparatus according to claim 3 or 4, characterized in that the catalyst carrier receiving the catalyst rests on the uppermost layer of the cooling tubes of the reaction gas cooler (3).
Vorrichtung nach einem der Ansprüche 3 bis 5, dadurch gekennzeichnet, daß die mit dem Reaktionsgas beaufschlagten Teile des Reaktors aus rostfreiem Stahl, Kupfer oder kupferplattiertem Stahl bestehen. Device according to one of claims 3 to 5, characterized in that the parts of the reactor which are acted upon by the reaction gas consist of stainless steel, copper or copper-clad steel.
EP99957687A 1998-12-10 1999-12-10 Method and device for producing formaldehyde Ceased EP1144104A1 (en)

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AT207398 1998-12-10
AT207398A AT412871B (en) 1998-12-10 1998-12-10 METHOD AND DEVICE FOR PREPARING FORMALDEHYDE
PCT/AT1999/000303 WO2000033952A1 (en) 1998-12-10 1999-12-10 Method and device for producing formaldehyde

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GB0907502D0 (en) * 2009-05-01 2009-06-10 Dynea Oy Catalyst reaction apparatus and process
CN108913896A (en) * 2018-09-14 2018-11-30 谢以贵 A kind of novel energy-conserving and not the titanium sponge reduction distillation system of consumption of reactor

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US2504402A (en) * 1945-10-27 1950-04-18 Du Pont Formaldehyde synthesis
US2908715A (en) * 1956-07-05 1959-10-13 Eguchi Takashi Process for preparing formalin by oxidation of methanol
DE1642955A1 (en) * 1968-03-05 1971-06-03 Basf Ag Process for dissipating heat
DE2002789A1 (en) * 1970-01-16 1971-07-22 Charbonnages Ste Chimique Device for the synthesis of formaldehyde
DE2137938A1 (en) * 1971-07-29 1973-02-15 Basf Ag Formaldehyde reactor - with a metal screen carrying the catalyst above the perforated reactor base
DE2444586C3 (en) * 1974-09-18 1986-07-10 Basf Ag, 6700 Ludwigshafen Process for the preparation of concentrated, aqueous solutions of formaldehyde
DE2546104C3 (en) * 1975-10-15 1980-10-23 Bayer Ag, 5090 Leverkusen Device for producing formaldehyde
DD249473B1 (en) * 1986-05-28 1989-12-13 Leipzig Chemieanlagen PROCESS FOR PREPARING FORMALDEHYDE
JPH0764774B2 (en) * 1987-07-24 1995-07-12 三井東圧化学株式会社 Method for preventing post-oxidation of methacrolein

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