APPARATUS FOR MIXING OF MEDIA

Description

[0001] The present invention relates to a device for mixing of two or several media.

[0002] Generally these kinds of devices are made as a type of vessel into which different media are fed and exposed to agitation by means of rotating or revolving stirrers. Usually the media are fed in continuously and the mixture is also discharged continuously. If the mixing takes place under high pressures the vessel has to be made as a pressure vessel and if the media are highly corrosive all parts, in contact with or exposed to the media, have to be made of materials resistive to corrosion.
Conventional mixers normally function satisfactorily, but are restricted to media which are relatively easy to mix. This is a disadvantage as a wide range of use would be preferable for the often very big and expensive mixers that are used, in the first place, within the process industry. When these mixers are made to resist highly corrosive media they tend to be even more expensive.

[0003] The type of mixer, according to the invention, is intended for use in ordinary mixing applications, when only a very effective degree of mixing is to be obtained, and also for very difficult applications in continuous processes with lignocellulosic material as media. The mixer will be able to operate highly viscosic media, such as suspensions of lignocellulosic fibres in water, with a concentration of dry substance as high as approximately 35 %. When required, the mixing in such applications will be possible to execute with such high power and energy input that the media will be fluidized.

[0004] It is well known, that cellulosic fibres have the ability to form a network unaided, a so called network of fibre, at relatively low consistencies. This leads to a rapid decrease in the mixtures ability to flow, like a "Newtonian liquid". If this phenomena cannot be overcome or eliminated it will strongly effect the result in a negative way when mixing additives like, bleaching chemicals, oxygen, acids, etc.

[0005] Acid hydrolysis of lignocellulosic materials can be used as an example. If a strong network of fibre exists, the added acid will not be distributed to the medium in an satisfactory way for this process. To arrange the condition for a proper admixture of the acid, and in this case not only to achieve a well defined start of the hydrolysis reaction, which is catalyzed by the acid, but also to achieve a proper result of hydrolysis, the network of fibre should be broken so that all the individual fibres can be reached rapidly by the acid. This can be achieved by an agitation of the fibre suspension strong enough to fluidize the mixture. The mixture will than start to behave like a "Newtonian liquid", which will allow a proper and homogeneous addition of the acid.
The transport of the mixture through the mixer will also be facilitated.
The mixer will also be constructed so that it can be equipped with an internal cover of special material as a protection from corrosion, without being too complicated or in any other way leading to unreasonable costs.

[0006] The purpose of the invention is to achieve a mixer which is unsophisticated, effective and easy to facilitate, and which also complies with above mentioned requirements.

[0007] This has, according to the invention, been reached by giving the mixer the distinctive features listed in the following claims. The housing of the mixer has a straight cylindrical form and the media, that should be mixed, are fed in through an opening in the mantle surface, essentially radial to the housing, where the media immediately in the opening are subject to a first mixing, or agitation, by the axial bars that sweep close to the inner wall of the cylindrical mixing housing. Inside the mixing housing, the media are transported perpendicular to the intake direction and are subject to at least one more mixing or agitation, but now perpendicular to the first mixing, by a rotating rotor cross with radial arms located in the open end of the mixing housing, coaxial with the housing. This especially contributes to a strong turbulence of the media mixture.

[0008] As an alternative the media could also be fed, through the mixing housing, in the other direction.
The invention is explained more clearly in the following text with reference to enclosed drawing which in a schematic way shows one example of design of a device according to the invention in which figure 1 is a side view of the device, partly in section, and figure 2 is an end view of the device.

[0009] It can be seen from the drawing that the device consists of three main parts, namely one straight cylindrical mixing housing 1, one straight cylindrical bearing housing 2 and one electrical motor 3, positioned at the end of the bearing housing. These three parts are connected to each other by flanges. At the mixing housing 1 a feed pipe 4 is welded at an opening 5 through the cylindrical wall 6 of the mixing housing. Inside the mixing housing 1 a revolvable rotor 7 is arranged. The rotor has one rotor cross, with radial arms 8, at the outlet opening 9 of the housing 1 and a similar rotor cross 10 at the other end of the housing 1, and the ends of the arms 8 are connected to the ends of the arms of the rotor cross 10 by four axial bars 15 which sweep along the inside of the housing 1 when the rotor is rotating.
The rotor cross 10 is fixed to a shaft 11 which goes through an opening in the end wall 12 of the bearing housing 2. End wall 12 is also, at the same time, the end wall of the mixing housing 1. The shaft 11 is supported by the bearings 13 in the bearing housing 2 and is connected to the motor 3 by a coupling 14. The passage of the shaft, through the opening of the end wall 12, is thoroughly sealed to resist high pressures as well as the effect of strongly corrosive media. It is then obvious that the bearing housing 2 and the motor 3, as a unit together with the rotor 7, which is introduced in the housing 1, can be mounted against the end flange of the housing 1 when assembling the device.

[0010] The rotor cross 10 has arms which are somewhat inclined to feed the media from the end wall 12, as are the bars 15, to feed the media from the inside of the wall 6 against the centre of the housing 1. Furthermore the axial bars 15 can be designed slightly curved to support the feed of the media through the housing 1 forwards the outlet opening 9. The arms 8, of the rotor cross in the outlet opening 9, are twisted and/or curved causing a strong turbulence when the media is passing.

[0011] If desired, one or several more rotor crosses can be arranged at the rotor 7 between the two which are shown in the drawing.

[0012] As a result of the described design of the mixing housing 1 and the inlet pipe 4 the possibility for the housing to handle high pressures will be very favourable.
The axial part of the housing has a diameter of 350 mm and a length of 600 mm. The inlet pipe 4 has a diameter of 325 mm. The housing 1 and the inlet pipe 4 are made of stainless steel and the inside are lined with a 4 mm thick plate of Zirconium 16.

[0013] The rotor 7 is manufactured of solid Zirconium and the design gives the suitable stability and strength to take the full torque that the motor 3 can give. This motor has an effect of 75 kW and a speed of 750 rpm, which gives the rotor a circumferential speed of 13,5 m/s.

[0014] The invention is naturally not restricted to the example shown and described here above. On the contrary, a number of modifications and variations are possible within the frame of the idea of the invention presented in the claims. As an example, the arms of the rotor crosses can be more or less than four. Furthermore the ends of the arms can be connected by a circular reinforcement if increased rigidity of the rotor is desired.

[0015] When the media are fed in the opposite direction to that shown in the example, the arms of the rotor crosses and the bars between the rotors naturally should be inclined with respect to the different direction of feed.

Claims

1. Device for mixing of two or several media, fed to the device, comprising a straight cylindrical mixing housing ( 1 ) in which a rotor ( 7 ) is geared by means of a bearing housing ( 2 ) mounted to one end of the mixing housing, which at the other end has an axial directed inlet or outlet opening ( 9 ); the rotor, driven by a drive shaft (11), is equipped with at least two rotor crosses, a first rotor cross (10), positioned close to the bearing housing, and a second rotor cross ( 8 ), positioned at the outlet or inlet opening ( 9 ), the rotor crosses have radial arms (8) and the ends of the first rotor cross ( 10 ) are connected with the corresponding ends of the second rotor cross by means of axial bars ( 15 ), which are arranged to sweep along the inside of the cylindrical part of the mixing housing (1), the device further comprising an inlet or outlet opening, ( 5 ) for the media, which is arranged at the cylindrical wall ( 6 ) of the mixing housing.

2. Device according to claim no. 1 characterized in, that the radial arms ( 8 ) of the rotor crosses are inclined so that the media are fed against the outlet opening ( 9 ) by the arms of the first rotor cross ( 10 ) and are given a strong turbulence by the arms of the second rotor cross ( 8 ).

3. Device according to claims no. 1 or 2, characterized in, that the bearing housing ( 2 ) has an end wall ( 12 ) that at the same time is an end wall of the mixing housing (1).

4. Device according to any of the claims no. 1 - 3, characterized in, that the axial bars ( 15 ) are fixed somewhat inclined to keep the inside of the cylindrical part of the mixing housing (1) clean.

5. Device according to any of the claims no.1 - 4, characterized in, that the axial bars ( 15 ) are slightly curved to feed the peripheral parts of the media forward, along the cylindrical inside of the mixing housing (1).

Ansprüche

1. Vorrichtung zum Vermischen von von zwei oder mehreren Medien, die der Vorrichtung zugeführt werden, mit einem geraden zylindrischen Mischgehäuse (1), in welchem ein Rotor (7) mit Hilfe eines Lagergehäuses (2) eingreift, das an einem Ende des Mischgehäuses (1) angebracht ist, das am anderen Ende eine axial ausgerichtete Einlaß- oder Auslaßöffnung (9) besitzt, wobei der Rotor, der durch eine Antriebswelle (11) angetrieben ist, mit wenigstens zwei Rotorkreuzen ausgerüstet ist, einem ersten Rotorkreuz (10), das in der Nähe des Lagergehäuses angeordnet ist, und einem zweiten Rotorkreuz (8), das an der Auslaß- oder Einlassöffnung (9) angeordnet ist, die Rotorkreuze radiale Arme (8) besitzen und die Enden des ersten Rotorkreuzes (10) mit den entsprechenden Enden des zweiten Rotorkreuzes mit axialen Gliedern (15) verbunden sind, die derart angeordnet sind, daß sie entlang der Innenseite des zylindrischen Teils des Mischgehäuses (1) streichen, wobei die Vorrichtung ferner eine Einlaß- oder Auslaßöffnung (5) für die Medien aufweist, die an der zylindrischen Wandung (6) des Mischgehäuses angeordnet ist.

2. Vorrichtung nach Anspruch 1, dadurch gekennzeichnet, daß die radialen Arme (8) der Rotorkreuze derart geneigt sind, daß die Medien durch die Arme des ersten Rotorkreuzes (10) zu der Auslaßöffnung (9) geführt und ihnen durch die Arme des zweiten Rotorkreuzes (8) starke Turbulenzen verliehen werden.

3. Vorrichtung nach Anspruch 1 oder 2, dadurch gekennzeichnet, daß das Lagergehäuse (2) eine Stirnwand (12) besitzt, die gleichzeitig eine Stirnwand des Mischgehäuses (1) bildet.

4. Vorrichtung nach einem der Ansprüche 1 bis 3, dadurch gekennzeichnet, daß die Axialglieder (15) etwas geneigt befestigt sind, um die Innenseite des zylindrischen Teils des Mischgehäuses (1) sauber zu halten.

5. Vorrichtung nach einem der Ansprüche 1 bis 4, dadurch gekennzeichnet, daß die Axialglieder (15) leicht gekrümmt sind, um die Umfangszonen der Medien vorwärts entlang der zylindrischen Innenseite des Mischgehäuses (1) zu fördern.

Revendications

1. Dispositif destiné à mélanger deux ou plusieurs milieux, délivrés au dispositif, comportant un boîtier de mélange cylindrique droit (1) dans lequel un rotor (7) est entraîné au moyen d'un boîtier de palier (2) monté sur une extrémité du boîtier de mélange qui, à l'autre extrémité, a une ouverture d'entrée ou de sortie orientée de manière axiale (9) ; le rotor, entraîné par un arbre d'entraînement (11), est équipé d'au moins deux croix de rotor, une première croix de rotor (10), positionnée près du boîtier de palier, et une deuxième croix de rotor (8), positionnée au niveau de l'ouverture de sortie ou d'entrée (9), les croix de rotor ont des bras radiaux (8) et les extrémités de la première croix de rotor (10) sont reliées aux extrémités correspondantes de la deuxième croix de rotor au moyen de barres axiales (15), qui sont prévues pour balayer le long de l'intérieur de la partie cylindrique du boîtier de mélange (1), le dispositif comportant en outre une ouverture d'entrée ou de sortie (5) pour les milieux, qui est disposée au niveau de la paroi cylindrique (6) du boîtier de mélange.

2. Dispositif selon la revendication 1, caractérisé en ce que les bras radiaux (8) des croix de rotor sont inclinés de telle sorte que les milieux sont délivrés contre l'ouverture de sortie (9) par les bras de la première croix de rotor (10) et entrent en forte turbulence grâce aux bras de la deuxième croix de rotor (8).

3. Dispositif selon la revendication 1 ou 2, caractérisé en ce que le boîtier de palier (2) a uhe paroi d'extrémité (12) qui est dans le même temps une paroi d'extrémité du boîtier de mélange (1).

4. Dispositif selon l'une quelconque des revendications 1 à 3, caractérisé en ce que les barres axiales (15) sont fixées légèrement inclinées afin de maintenir propre l'intérieur de la partie cylindrique du boîtier de mélange (1).

5. Dispositif selon l'une quelconque des revendications 1 à 4, caractérisé en ce que les barres axiales (15) sont légèrement courbes afin de délivrer les parties périphériques des milieux vers l'avant, le long de l'intérieur cylindrique du boîtier de mélange (1).

Drawing