EP0347653A2 - Mixing receptacle with radial transport stirrer and at least one flow breaker as well as process for liquid mixing using this mixing receptacle - Google Patents

Mixing receptacle with radial transport stirrer and at least one flow breaker as well as process for liquid mixing using this mixing receptacle Download PDF

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Publication number
EP0347653A2
EP0347653A2 EP89110337A EP89110337A EP0347653A2 EP 0347653 A2 EP0347653 A2 EP 0347653A2 EP 89110337 A EP89110337 A EP 89110337A EP 89110337 A EP89110337 A EP 89110337A EP 0347653 A2 EP0347653 A2 EP 0347653A2
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Prior art keywords
mixing
stirred tank
stirrer
baffle
stirred
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EP89110337A
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German (de)
French (fr)
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EP0347653B1 (en
EP0347653A3 (en
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Franz-Michael Dr. Bollenrath
Josef Karl Dr. Rigler
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Huels AG
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Huels AG
Chemische Werke Huels AG
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01F—MIXING, e.g. DISSOLVING, EMULSIFYING OR DISPERSING
    • B01F27/00—Mixers with rotary stirring devices in fixed receptacles; Kneaders
    • B01F27/80—Mixers with rotary stirring devices in fixed receptacles; Kneaders with stirrers rotating about a substantially vertical axis
    • B01F27/86—Mixers with rotary stirring devices in fixed receptacles; Kneaders with stirrers rotating about a substantially vertical axis co-operating with deflectors or baffles fixed to the receptacle
    • B01F27/862—Mixers with rotary stirring devices in fixed receptacles; Kneaders with stirrers rotating about a substantially vertical axis co-operating with deflectors or baffles fixed to the receptacle the baffles being adjustable or movable

Definitions

  • the homogeneous mixing of liquids in reactors, especially in large reactors, is by no means unproblematic. Not only should a good mixing effect be achieved, there should also be no foaming.
  • the liquid for example a polymerization batch, should not form a vortex and in particular should not draw in any gas. Caking should be avoided since it often leads to product damage and inhomogeneities. As is known, it is particularly difficult to achieve homogeneous mixing in liquids which consist of two or more liquid components of different densities.
  • a common stirrer type e.g. B. a disc stirrer (Rushton turbine)
  • a stirred tank diameter D
  • a Rushton turbine are used and four baffles approximately D / 10 wide are installed along the wall of the stirred tank.
  • the disadvantage is that these baffles are not adjustable and can therefore not be adapted to the respective stirring problems.
  • the formation of caking can usually not be avoided on the baffles, which require a considerably increased power input.
  • DE-OS 32 02 159 discloses a process for the preparation of styrene polymers with the addition of low-boiling propellants, in which it is important to obtain a surface that is as free as possible of pellets while stirring. It is proposed, inter alia, to use a stirring system which consists of a stirred kettle, an axially arranged stirrer, preferably an impeller stirrer and a Pfaudler-type finger flow disturbance which is arranged in the vicinity of the stirrer. Such a stirring system can be used above all if the filling height is not greater than the bowl diameter. Problems arise with stirred tanks that are filled higher. It can be seen from the examples that the product quality is considerably deteriorated if the work is not carried out free of leaks.
  • a stirred tank 1 has now been found, which is equipped with a radially conveying stirrer 3 and at least one adjustable baffle 2 and is characterized by the following features: -
  • the radially conveying stirrer 3 preferably an impeller stirrer, is mounted at a maximum distance D / 2 from the bottom of the stirred tank.
  • the baffle or baffles 2 are in the upper half of the stirred tank.
  • the baffle or baffles 2 have the shape of an airfoil profile, ie they are curved in the form of an Archimedean spiral or in the form of part or parts of an arc.
  • the or the baffle 2 are attached at a distance R1 with D / 8 ⁇ R1 ⁇ D / 3 from the wall.
  • the baffle ( s) have the height h s , for which the following relationship preferably applies: 0.2 ⁇ h s / D ⁇ 0.4 -
  • the outflow cross section of the baffle or baffles is preferably rectangular.
  • the invention further relates to a method for mixing liquids using the stirred tank just described.
  • the stirred kettle used according to this invention is a standing stirred kettle 1 with a usually vertical axis and cylindrical shape.
  • the ratio between its height H and its diameter D is usually greater than 1, in particular it is between 1.5 and 2.5.
  • the stirred tank 1 usually has a wicker, ball or dished bottom. The latter is preferred.
  • the total volume of the stirred tank is not critical.
  • stirrer 3 It is usually equipped with a single-stage stirrer 3 near the bottom. It is therefore not necessary, as is often the case with other types of stirrer in difficult cases, to equip it with a multi-stage stirrer or with several stirrers.
  • the shape of the stirrer 3 corresponds to that of an impeller stirrer. Its diameter d is 0.5 D to 0.7 D, the leaf height is 0.2 d.
  • the angle with respect to the horizontal is usually adapted to the shape of the bottom of the stirred tank.
  • the stirred tank 1 contains at least one rotatable baffle 2 ; preferably there are two. These are expediently attached in such a way that they are immersed in the upper third of the liquid in the reactor and the distance between their pivot point and the boiler wall is between 0.1 D and 0.2 D.
  • the angle of attack alpha is preferably between 0 and 60 ° (see Fig. 1).
  • the cross-sectional area of the baffle 2 resembles an airfoil profile, the center line of which is preferably designed as a piece of an Archimedean spiral. For technical reasons, this is often replaced by an arc.
  • the radius of this circle is between approximately 0.15 D and 0.3 D.
  • the baffle 2 can have the shape of a sheet whose cross-section corresponds to the center line described.
  • the height of the baffle 2 is usually between 0.2 D and 0.5 D.
  • the stirred tank 1 according to the invention is used particularly advantageously when dispersions of two different, immiscible liquids of different densities have to be maintained.
  • foam polystyrene Such a problem arises, for example, in the production of foam polystyrene.
  • An aqueous suspension containing styrene polymers and unreacted monomeric styrene is mixed with blowing agent, for. B. pentane.
  • DE-OS 32 02 159 shows that the product properties of foam polystyrene are significantly influenced by the stirring process. The good axial mixing is particularly noticeable here.
  • Another area of application relates to the polymerization of suspension PVC.
  • foam is formed on the surface of the reaction mixture during the polymerization. In the case of reactors equipped with reflux coolers, this foam also settles in the lower part of the cooler. The result is relocation, material damage and failure of the cooler. If the stirring system just described is used in this critical phase of the polymerization, the formation of foam can in many cases be avoided entirely.
  • Fig. 1 shows a stirred tank according to the invention.
  • the direction of rotation of the stirrer is designated 4 .
  • Example 8 of DE-OS 32 02 159 shows that, using the stirred kettle shown in Fig. 1 of this document, stirring with the DAT stirring system can be carried out without dripping and good product properties can be obtained. In this case, however, you have to rely on a stirred tank with two independent stirrers. This is comparatively complex.
  • Example 11 of DE-OS 32 02 159 shows that using the stirred tank shown in Fig. 1 of this document with a Pfaudler stirring system at low fill levels, products of unsatisfactory quality are obtained.
  • Example 1 of DE-OS 32 02 159 shows that using the stirred kettle shown in Fig. 2 of this document with a Pfaudler stirring system at a fill level of 90%, products of unsatisfactory quality are also obtained.

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  • Chemical & Material Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Mixers Of The Rotary Stirring Type (AREA)
  • Catching Or Destruction (AREA)
  • Physical Or Chemical Processes And Apparatus (AREA)
  • Polymerisation Methods In General (AREA)
  • Injection Moulding Of Plastics Or The Like (AREA)
  • Adhesives Or Adhesive Processes (AREA)

Abstract

Ziel der Erfindung war es, Rührsysteme zu entwickeln, die eine schnelle axiale Durchmischung von Flüssigkeiten unterschiedlicher Dichten ohne Bildung von Schaum ermöglichen.The aim of the invention was to develop stirring systems which enable rapid axial mixing of liquids of different densities without the formation of foam.

Der aufgefundene Rührkessel 1 zeichnet sich dadurch aus, daß er mit einem radial fördernden Rührer 3 und mindestens einem Strom­störer 2 ausgestattet ist, wobei letzterer die Form eines Tragflä­chenprofils aufweist.The stirred kettle 1 found is characterized in that it is equipped with a radially conveying stirrer 3 and at least one baffle 2 , the latter having the shape of an airfoil profile.

Der Rührkessel eignet sich insbesondere zur homogenen Durchmi­schung von Flüssigkeiten in Großreaktoren. The stirred tank is particularly suitable for homogeneous mixing of liquids in large reactors.

Description

Die homogene Durchmischung von Flüssigkeiten in Reaktoren, insbeson­dere in Großreaktoren, ist keineswegs unproblematisch. Es soll nicht nur ein guter Durchmischungseffekt erzielt werden, es soll auch zu keiner Schaumentwicklung kommen. Die Flüssigkeit, beispielsweise ein Polymerisationsansatz, soll keine Trombe bilden und insbesondere kein Gas einziehen. Anbackungen sollen vermieden werden, da sie vielfach zu Produktschädigungen und Inhomogenitäten führen. Bekanntlich ist es be­sonders schwierig, eine homogene Durchmischung bei Flüssigkeiten zu erzielen, die aus zwei oder mehr flüssigen Komponenten unterschied­licher Dichte bestehen.The homogeneous mixing of liquids in reactors, especially in large reactors, is by no means unproblematic. Not only should a good mixing effect be achieved, there should also be no foaming. The liquid, for example a polymerization batch, should not form a vortex and in particular should not draw in any gas. Caking should be avoided since it often leads to product damage and inhomogeneities. As is known, it is particularly difficult to achieve homogeneous mixing in liquids which consist of two or more liquid components of different densities.

In all diesen Fällen führen konventionelle Rührkessel zu unbefriedi­genden Ergebnissen.In all of these cases, conventional stirred kettles lead to unsatisfactory results.

Setzt man nämlich einen üblichen Rührertyp, z. B. einen Scheibenrüh­rer (Rushton-Turbine), ein, erzielt man zwar eine gute horizontale, aber eine außerordentlich schlechte axiale Durchmischung. Die Trom­benbildung läßt sich am einfachsten dadurch vermeiden, daß man zusätz­lich Stromstörer einbaut. Bei einer üblichen Ausführungsform verwendet man einen Rührkessel (Durchmesser D) und eine Rushton-Turbine und bringt vier Leitbleche einer Breite von etwa D/10 längs der Rührkes­selwand an. Nachteilig ist, daß diese Stromstörer nicht verstellbar sind und daher nicht den jeweiligen Rührproblemen angepaßt werden kön­nen. An den Stromstörern, die einen erheblich erhöhten Leistungsein­trag erfordern läßt sich die Ausbildung von Anbackungen meist nicht vermeiden.If you set a common stirrer type, e.g. B. a disc stirrer (Rushton turbine), one achieves a good horizontal, but an extremely poor axial mixing. The easiest way to avoid the formation of drums is to install additional baffles. In a common embodiment, a stirred tank (diameter D) and a Rushton turbine are used and four baffles approximately D / 10 wide are installed along the wall of the stirred tank. The disadvantage is that these baffles are not adjustable and can therefore not be adapted to the respective stirring problems. The formation of caking can usually not be avoided on the baffles, which require a considerably increased power input.

Sehr gute Mischergebnisse werden nach dem Stand der Technik mit dem Pfaudler-System erzielt (vgl. Prospekt der Pfaudler-Werke, D-6830 Schwetzingen, 1978). Als Rührer wird üblicherweise ein Impeller-Rührer nach Pfaudler verwendet. Zwischen dem Rührerdurchmesser d und der Höhe des Rührblattes b besteht der Zusammenhang d/10 = b. Die drehbar ge­lagerten Stromstörer, mit üblicherweise drei Fingern (Mixing in the Chemical Industry, Pergamon Press, I. Sterbacek, Tausk, 1965, S. 281), deren Enden verbunden sein können, sitzen meistens unmittelbar über dem Rührer. Während die Durchmischung im unteren Bereich des Rühr­kessels zufriedenstellend ist, gibt es inbesondere bei großen und schlanken Rührkesseln Probleme mit der axialen Durchmischung, es sei denn, die Rührleistung wird erheblich gesteigert, was wiederum zur unerwünschten Trombenbildung führt.According to the state of the art, very good mixing results are achieved with the Pfaudler system (cf. prospectus of the Pfaudler works, D-6830 Schwetzingen, 1978). A Pfaudler impeller stirrer is usually used as the stirrer. Between the stirrer diameter d and the height The stirring blade b has the relationship d / 10 = b. The rotatable baffles, usually with three fingers (Mixing in the Chemical Industry, Pergamon Press, I. Sterbacek, Tausk, 1965, p. 281), the ends of which can be connected, are usually located directly above the stirrer. While the mixing in the lower region of the stirred tank is satisfactory, there are problems with the axial mixing, especially in the case of large and slim stirred tanks, unless the stirring power is increased considerably, which in turn leads to undesirable formation of droplets.

Aus der DE-OS 32 02 159 ist ein Verfahren zur Herstellung von Styrol­polymerisaten unter Zusatz von niedrig siedenden Treibmitteln bekannt, bei dem es darauf ankommt, während des Rührens eine möglichst tromben­freie Oberfläche zu erhalten. Es wird unter anderem vorgeschlagen, ein Rührsystem zu verwenden, das aus einem Rührkessel, einem axial ange­ordnetem Rührer, vorzugsweise einem Impellerrührer und einem Finger­stromstörer nach Pfaudler-Bauweise, der in der Nähe des Rührers ange­ordnet ist, besteht. Ein solches Rührsystem ist vor allem dann ein­setzbar, wenn die Füllhöhe nicht größer als der Kesseldurchmesser ist. Bei Rührkesseln, die höher gefüllt sind, treten Probleme auf. Den Bei­spielen ist zu entnehmen, daß die Produktqualität erheblich ver­schlechtert ist, wenn man nicht trombenfrei arbeitet.DE-OS 32 02 159 discloses a process for the preparation of styrene polymers with the addition of low-boiling propellants, in which it is important to obtain a surface that is as free as possible of pellets while stirring. It is proposed, inter alia, to use a stirring system which consists of a stirred kettle, an axially arranged stirrer, preferably an impeller stirrer and a Pfaudler-type finger flow disturbance which is arranged in the vicinity of the stirrer. Such a stirring system can be used above all if the filling height is not greater than the bowl diameter. Problems arise with stirred tanks that are filled higher. It can be seen from the examples that the product quality is considerably deteriorated if the work is not carried out free of leaks.

Ziel der vorliegenden Erfindung war es daher, Rührsysteme zu ent­wickeln, die folgende Eigenschaften aufweisen:

  • 1. Sie sollten eine schnelle axiale Durchmischung von Flüssigkeiten unterschiedlicher Dichten ermöglichen.
  • 2. Beim Rühren sollte sich kein Schaum entwickeln.
  • 3. Beim Rühren sollte sich keine oder nur eine unwesentliche Trombe bilden.
  • 4. Beim Rühren sollte kein Gas eingezogen werden.
  • 5. Das Rührsystem sollte auch bei großen Füllhöhen HL zuverlässig arbeiten (HL/D > 1)
The aim of the present invention was therefore to develop stirring systems which have the following properties:
  • 1. They should enable rapid axial mixing of liquids of different densities.
  • 2. No foam should develop when stirring.
  • 3. No stirring or only an insignificant drum should form when stirring.
  • 4. No gas should be drawn in when stirring.
  • 5. The stirring system should work reliably even at high filling levels H L (H L / D> 1)

Es wurde jetzt ein Rührkessel 1 gefunden, der mit einem radial för­dernden Rührer 3 und mindestens einem verstellbaren Stromstörer 2 aus­gestattet ist und durch folgende Merkmale gekennzeichnet ist:
- Der radial fördernde Rührer 3, vorzugsweise ein Impellerrührer, ist maximal in einem Abstand D/2 vom Rührkesselboden entfernt ange­bracht.
- Der oder die Stromstörer 2 befinden sich in der oberen Hälfte des Rührkessels.
- Der bzw. die Stromstörer 2 haben die Form eines Tragflächenprofils, d. h. sie sind in Form einer archimedischen Spirale oder in Form eines Teiles oder Teilen eines Kreisbogens gekrümmt.
- Der bzw. die Stromstörer 2 sind in einem Abstand R₁ mit D/8 < R1 < D/3 von der Wand entfernt angebracht.
- Der bzw. die Stromstörer besitzen die Höhe hs, für die vorzugsweise folgende Beziehung gilt:
0,2 < hs/D < 0,4
- Der Ausströmquerschnitt des bzw. der Stromstörer ist vorzugsweise rechteckig.A stirred tank 1 has now been found, which is equipped with a radially conveying stirrer 3 and at least one adjustable baffle 2 and is characterized by the following features:
- The radially conveying stirrer 3 , preferably an impeller stirrer, is mounted at a maximum distance D / 2 from the bottom of the stirred tank.
- The baffle or baffles 2 are in the upper half of the stirred tank.
- The baffle or baffles 2 have the shape of an airfoil profile, ie they are curved in the form of an Archimedean spiral or in the form of part or parts of an arc.
- The or the baffle 2 are attached at a distance R₁ with D / 8 <R1 <D / 3 from the wall.
- The baffle ( s) have the height h s , for which the following relationship preferably applies:
0.2 <h s / D <0.4
- The outflow cross section of the baffle or baffles is preferably rectangular.

Gegenstand der Erfindung ist ferner gemäß Anspruch 6 ein Verfahren zum Durchmischen von Flüssigkeiten mit Hilfe des soeben beschriebenen Rührkessels.The invention further relates to a method for mixing liquids using the stirred tank just described.

Mit der vorliegenden Erfindung werden folgende Vorteile erzielt:

  • 1. Die gesamte Flüssigkeitsmenge wird homogen durchmischt.
  • 2. Es wird eine hohe axiale Umwälzung erreicht.
  • 3. Die Form der Stromstörer 2 garantiert einen erstaunlich geringen Leistungsbedarf.
  • 4. Die Flüssigkeit wird trombenfrei gerührt.
  • 5. Die Stromstörer 2 können sowohl in ihrer Höhe als auch in ihrem Winkel gegenüber der zu rührenden Flüssigkeit verstellt werden und damit auch sehr unterschiedlichen Rührproblemen angepaßt werden.
  • 6. Bei Verwendung eines radial fördernden Rührers mit Untenantrieb kommt man mit einer sehr kurzen Rührerwelle aus.
The following advantages are achieved with the present invention:
  • 1. The entire amount of liquid is mixed homogeneously.
  • 2. A high axial circulation is achieved.
  • 3. The shape of the baffle 2 guarantees an astonishingly low power requirement.
  • 4. The liquid is stirred free of bubbles.
  • 5. The baffle 2 can be adjusted both in height and in their angle with respect to the liquid to be stirred and thus very different stirring problems can be adapted.
  • 6. When using a radially conveying stirrer with bottom drive, a very short stirrer shaft is sufficient.

Bei dem Rührkessel, der nach dieser Erfindung eingesetzt wird, handelt es sich um einen stehenden Rührkessel 1 mit üblicherweise vertikaler Achse und zylindrischer Form. Das Verhältnis zwischen seiner Höhe H und seinem Durchmesser D ist meist größer als 1, insbesondere liegt es zwischen 1,5 und 2,5. Der Rührkessel 1 weist üblicherweise einen Korb­bogen-, Kugel- oder Klöpperboden auf. Letzterer ist bevorzugt. Das Gesamtvolumen des Rührkessels ist nicht kritisch.The stirred kettle used according to this invention is a standing stirred kettle 1 with a usually vertical axis and cylindrical shape. The ratio between its height H and its diameter D is usually greater than 1, in particular it is between 1.5 and 2.5. The stirred tank 1 usually has a wicker, ball or dished bottom. The latter is preferred. The total volume of the stirred tank is not critical.

Er ist üblicherweise mit einem einstufigen Rührer 3 in Bodennähe aus­gerüstet. Es ist also nicht erforderlich, wie dies bei anderen Rühr­typen in schwierigen Fällen vielfach geschieht, ihn mit einem mehr­stufigen Rührer oder mit mehreren Rührern auszurüsten. Die Form des Rührers 3 entspricht der eines Impellerrührers. Sein Durchmesser d beträgt 0,5 D bis 0,7 D, die Blatthöhe liegt bei 0,2 d. Der Winkel gegenüber der Horizontalen ist üblicherweise der Bodenform des Rühr­kessels angepaßt.It is usually equipped with a single-stage stirrer 3 near the bottom. It is therefore not necessary, as is often the case with other types of stirrer in difficult cases, to equip it with a multi-stage stirrer or with several stirrers. The shape of the stirrer 3 corresponds to that of an impeller stirrer. Its diameter d is 0.5 D to 0.7 D, the leaf height is 0.2 d. The angle with respect to the horizontal is usually adapted to the shape of the bottom of the stirred tank.

Der Rührkessel 1 enthält mindestens einen drehbar angeordneten Strom­störer 2; vorzugsweise sind es zwei. Diese sind zweckmäßigerweise so angebracht, daß sie in das obere Drittel der im Reaktor stehenden Flüssigkeit eintauchen und der Abstand ihres Drehpunktes von der Kes­selwand zwischen 0,1 D und 0,2 D beträgt. Der Anstellwinkel Alpha liegt vorzugsweise zwischen 0 und 60° (siehe Abb. 1).The stirred tank 1 contains at least one rotatable baffle 2 ; preferably there are two. These are expediently attached in such a way that they are immersed in the upper third of the liquid in the reactor and the distance between their pivot point and the boiler wall is between 0.1 D and 0.2 D. The angle of attack alpha is preferably between 0 and 60 ° (see Fig. 1).

Die Querschnittsfläche des Stromstörers 2 ähnelt einem Tragflächenpro­fil, dessen Mittenlinie vorzugsweise als Stück einer archimedischen Spirale ausgebildet ist. Aus fertigungstechnischen Gründen wird dieses vielfach durch einen Kreisbogen ersetzt. Der Radius dieses Kreises liegt zwischen etwa 0,15 D und 0,3 D. Im einfachsten Fall kann der Stromstörer 2 die Form eines Bleches haben, dessen Querschnitt der beschriebenen Mittenlinie entspricht. Die Höhe des Stromstörers 2 liegt üblicherweise zwischen 0,2 D und 0,5 D.The cross-sectional area of the baffle 2 resembles an airfoil profile, the center line of which is preferably designed as a piece of an Archimedean spiral. For technical reasons, this is often replaced by an arc. The radius of this circle is between approximately 0.15 D and 0.3 D. In the simplest case, the baffle 2 can have the shape of a sheet whose cross-section corresponds to the center line described. The height of the baffle 2 is usually between 0.2 D and 0.5 D.

Der erfindungsgemäße Rührkessel 1 wird besonders vorteilhaft einge­setzt, wenn Dispersionen aus zwei verschiedenen, nicht miteinander mischbaren Flüssigkeiten unterschiedlicher Dichte aufrecht erhalten werden müssen.The stirred tank 1 according to the invention is used particularly advantageously when dispersions of two different, immiscible liquids of different densities have to be maintained.

Ein derartiges Problem tritt beispielsweise bei der Herstellung von Schaumpolystyrol auf. Eine wäßrige Suspension, die Styrolpolymerisate und unumgesetztes monomeres Styrol enthält, wird mit Treibmittel, z. B. Pentan, versetzt. Der DE-OS 32 02 159 ist zu entnehmen, daß die Produkteigenschaften des Schaumpolystyrols wesentlich durch den Rührvorgang beeinflußt werden. Die gute axiale Durchmischung macht sich hier besonderes positiv bemerkbar.Such a problem arises, for example, in the production of foam polystyrene. An aqueous suspension containing styrene polymers and unreacted monomeric styrene is mixed with blowing agent, for. B. pentane. DE-OS 32 02 159 shows that the product properties of foam polystyrene are significantly influenced by the stirring process. The good axial mixing is particularly noticeable here.

Ein anderes Anwendungsgebiet betrifft die Polymerisation von Suspen­sions-PVC. Hier kommt es unter bestimmten Umständen während der Poly­merisation zur Bildung von Schaum auf der Oberfläche des Reaktionsan­satzes. Bei Reaktoren, die mit Rückflußkühlern ausgestattet sind, setzt sich dieser Schaum auch im unteren Teil des Kühlers ab. Es kommt in der Folge zu Verlegungen, Materialschädigungen und zum Ausfall des Kühlers. Setzt man in dieser kritischen Phase der Polymerisation das soeben beschriebene Rührsystem ein, läßt sich die Bildung von Schaum vielfach ganz vermeiden.Another area of application relates to the polymerization of suspension PVC. Under certain circumstances, foam is formed on the surface of the reaction mixture during the polymerization. In the case of reactors equipped with reflux coolers, this foam also settles in the lower part of the cooler. The result is relocation, material damage and failure of the cooler. If the stirring system just described is used in this critical phase of the polymerization, the formation of foam can in many cases be avoided entirely.

Die nachfolgenden Versuche beziehen sich auf das in der DE-OS 32 02 159 beschriebene Verfahren zur Herstellung von feinteiligen, ex­andierbaren Styrolpolymerisaten. Die Abb. 1 zeigt einen erfindungsge­mäßen Rührkessel. Die Drehrichtung des Rührers ist mit 4 bezeichnet.The following experiments relate to the process described in DE-OS 32 02 159 for the production of finely divided, expandable styrene polymers. Fig. 1 shows a stirred tank according to the invention. The direction of rotation of the stirrer is designated 4 .

Vergleichsbeispiel AComparative Example A

Das Beispiel 8 der DE-OS 32 02 159 zeigt, daß man unter Verwendung des in Abb. 1 dieser Schrift abgebildeten Rührkessel mit dem DAT-Rühr­system trombenfrei rühren und gute Produkteigenschaften erhalten kann. Allerdings ist man in diesem Fall auf einen Rührkessel mit zwei von­einander unabhängigen Rührern angewiesen. Dies ist vergleichsweise aufwendig.Example 8 of DE-OS 32 02 159 shows that, using the stirred kettle shown in Fig. 1 of this document, stirring with the DAT stirring system can be carried out without dripping and good product properties can be obtained. In this case, however, you have to rely on a stirred tank with two independent stirrers. This is comparatively complex.

Vergleichsbeispiel BComparative Example B

Das Beispiel 11 der DE-OS 32 02 159 zeigt, daß man unter Verwendung des in Abb. 1 dieser Schrift abgebildeten Rührkessels mit einem Pfaud­ler-Rührsystem bei niedrigen Füllhöhen Produkte unbefriedigender Qua­lität erhält.Example 11 of DE-OS 32 02 159 shows that using the stirred tank shown in Fig. 1 of this document with a Pfaudler stirring system at low fill levels, products of unsatisfactory quality are obtained.

Vergleichsbeispiel CComparative Example C

Das Beispiel 1 der DE-OS 32 02 159 zeigt, daß man unter Verwendung des in Abb. 2 dieser Schrift abgebildeten Rührkessels mit einem Pfaudler-­Rührsystem bei einer Füllhöhe von 90 % ebenfalls Produkte unbefriedi­gender Qualität erhält.Example 1 of DE-OS 32 02 159 shows that using the stirred kettle shown in Fig. 2 of this document with a Pfaudler stirring system at a fill level of 90%, products of unsatisfactory quality are also obtained.

Beispiel 1example 1

Man setzt anstelle des in Beispiel 1 der DE-OS 32 02 159 beschriebenen Rührkessels mit dem Pfaudler-Rührsystem den erfindungsgemäßen Rührkes­sel ein. Es handelt sich um einen Impellerrührer, der vollständig in die Flüssigkeit eintaucht. Es werden 2 Stromstörer mit einem kreisför­migen Tragflächenprofil eingesetzt. Folgende Abmessungen wurden ermit­telt: V = 40 l D = 350 mn d = 250 mm n = 120 Min⁻¹ R₁ = 50 mm Alpha = 20° Instead of the stirred tank described in Example 1 of DE-OS 32 02 159 with the Pfaudler stirring system, the stirred tank according to the invention is used. It is an impeller stirrer that is completely immersed in the liquid. Two baffles with a circular wing profile are used. The following dimensions were determined: V = 40 l D = 350 mn d = 250 mm n = 120 min⁻¹ R₁ = 50 mm alpha = 20 °

Selbst bei einer Füllhöhe von 90 % und dementsprechend hohen Rührdreh­zahlen erhält man während des Rührens keine Trombe. Die Produktquali­tät entspricht der von Beispiel 1 (siehe Tabelle 1 auf Seite 14 der DE-OS 32 02 159).Even with a filling level of 90% and correspondingly high stirring speeds, no drum is obtained during stirring. The product quality corresponds to that of Example 1 (see Table 1 on page 14 of DE-OS 32 02 159).

Claims (6)

1. Rührkessel 1 mit Durchmesser D, der mit mindestens einem verstell­baren Stromstörer 2 und einem radial fördernden Rührer 3, der in einem Abstand vom maximal D/2 vom Rührkesselboden entfernt ange­bracht ist, ausgestattet ist,
dadurch gekennzeichnet,
daß der bzw. die Stromstörer 2 1. sich in der oberen Hälfte des Rührkessels befinden, 2. in einem Abstand R₁ von der Rührkesselwand angebracht sind, wobei die Beziehung
D/8 < R₁ < D/3
gilt, 3. eine Höhe hs besitzen und 4. die Form eines Tragflächenprofils aufweisen, d. h. in Form einer archimedischen Spirale oder in Form eines Teiles eines Kreisbo­gens gekrümmt sind. 1. stirred tank 1 with diameter D, which is equipped with at least one adjustable baffle 2 and a radially conveying stirrer 3 , which is mounted at a distance of at most D / 2 from the bottom of the stirred tank,
characterized,
that the baffle (s ) 2 1. are in the upper half of the stirred tank, 2. are attached at a distance R₁ from the stirred tank wall, the relationship
D / 8 <R₁ <D / 3
applies 3. have a height h s and 4. have the shape of an airfoil profile, ie they are curved in the form of an Archimedean spiral or in the form of part of a circular arc. 2. Rührkessel nach Anspruch 1,
dadurch gekennzeichnet,
daß der Rührer ein Impellerrührer mit Untenantrieb ist.2. stirred tank according to claim 1,
characterized,
that the stirrer is an impeller stirrer with a bottom drive. 3. Rührkessel nach den Ansprüchen 1 und 2,
dadurch gekennzeichnet,
daß die Zahl der Stromstörer 2 1 bis 4, vorzugsweise 2, beträgt.3. stirred kettle according to claims 1 and 2,
characterized,
that the number of baffles 2 is 1 to 4, preferably 2. 4. Rührkessel nach den Ansprüchen 1 bis 4,
dadurch gekennzeichnet,
daß für die Höhe des Stromstörers 2 hs folgende Beziehung gilt:
0,2 < hs/D < 0,44. stirred tank according to claims 1 to 4,
characterized,
that the following relationship applies to the height of the baffle 2 h s :
0.2 <h s / D <0.4 5. Rührkessel nach den Ansprüchen 1 bis 5,
dadurch gekennzeichnet,
daß der Anströmquerschnitt des bzw. der Stromstörer 2 in Drehrich­tung 4 rechteckig ist.5. stirred kettle according to claims 1 to 5,
characterized,
that the flow cross-section of the baffle 2 is rectangular in the direction of rotation 4 . 6. Verfahren zum Durchmischen von Flüssigkeiten unter Verwendung eines Rührkessels gemäß den Ansprüchen 1 bis 5, wobei das Verhältnis zwi­schen Füllhöhe HL und Durchmesser D größer als 1 ist.6. A method for mixing liquids using a stirred tank according to claims 1 to 5, wherein the ratio between fill height H L and diameter D is greater than 1.
EP89110337A 1988-06-22 1989-06-08 Mixing receptacle with radial transport stirrer and at least one flow breaker as well as process for liquid mixing using this mixing receptacle Expired - Lifetime EP0347653B1 (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
AT89110337T ATE87233T1 (en) 1988-06-22 1989-06-08 STIRRING TANK WITH RADIAL CONVEYING STIRRER AND AT LEAST ONE FLOOR AND METHOD FOR MIXING LIQUIDS WITH THE HELP OF THIS STIRRING TANK.

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE3821033 1988-06-22
DE3821033A DE3821033A1 (en) 1988-06-22 1988-06-22 STIRRING BOILER WITH RADIAL CONVEYOR AND AT LEAST ONE ELECTRIC BURNER AND METHOD FOR MIXING LIQUIDS WITH THE HELP OF THIS STIRRING BOILER

Publications (3)

Publication Number Publication Date
EP0347653A2 true EP0347653A2 (en) 1989-12-27
EP0347653A3 EP0347653A3 (en) 1991-10-16
EP0347653B1 EP0347653B1 (en) 1993-03-24

Family

ID=6356992

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Application Number Title Priority Date Filing Date
EP89110337A Expired - Lifetime EP0347653B1 (en) 1988-06-22 1989-06-08 Mixing receptacle with radial transport stirrer and at least one flow breaker as well as process for liquid mixing using this mixing receptacle

Country Status (6)

Country Link
US (1) US4984899A (en)
EP (1) EP0347653B1 (en)
JP (1) JP2755694B2 (en)
AT (1) ATE87233T1 (en)
DE (2) DE3821033A1 (en)
FI (1) FI91365C (en)

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EP0633060A1 (en) * 1993-07-08 1995-01-11 Biazzi Sa Apparatus for gas-liquid reactions

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US6467947B1 (en) * 1997-08-19 2002-10-22 Commonwealth Scientific And Industrial Research Organisation Method and apparatus for mixing
US6059448A (en) * 1998-09-02 2000-05-09 Pfaudler, Inc. Concave baffle
JP2003033635A (en) * 2001-05-17 2003-02-04 Shinko Pantec Co Ltd Stirring blade, stirring device and stirring method using the same
DE10234426A1 (en) * 2001-09-14 2003-04-03 Wolff Cellulosics Gmbh & Co Kg Process and apparatus for the industrial production of methylhydroxyalkyl cellulose
ATE359303T1 (en) 2001-09-14 2007-05-15 Wolff Cellulosics Gmbh & Co Kg METHOD AND DEVICE FOR THE INDUSTRIAL PRODUCTION OF METHYLHYDROXYALKYLCULOSE
JP5493662B2 (en) * 2009-09-30 2014-05-14 栗田工業株式会社 Fluidized bed biological treatment equipment
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Publication number Priority date Publication date Assignee Title
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US5478535A (en) * 1993-07-08 1995-12-26 Biazzi Sa Apparatus for gas - liquid reactions

Also Published As

Publication number Publication date
JPH0248027A (en) 1990-02-16
FI91365C (en) 1994-06-27
EP0347653B1 (en) 1993-03-24
JP2755694B2 (en) 1998-05-20
US4984899A (en) 1991-01-15
FI892987A7 (en) 1989-12-23
ATE87233T1 (en) 1993-04-15
FI91365B (en) 1994-03-15
DE58903868D1 (en) 1993-04-29
FI892987A0 (en) 1989-06-19
EP0347653A3 (en) 1991-10-16
DE3821033A1 (en) 1989-12-28

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