Definitions

• the present invention relates to a device for mixing of two or several media.
• 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.
• the type of mixer 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 %.
• highly viscosic media such as suspensions of lignocellulosic fibres in water, with a concentration of dry substance as high as approximately 35 %.
• 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 hquid". 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.
• 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.
• 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 ofthe 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 ofthe acid.
• the transport ofthe 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.
• the purpose ofthe invention is to achieve a mixer which is unsophisticated, effective and easy to facilitate, and which also complies with above mentioned requirements.
• the housing ofthe 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 ofthe cylindrical 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 ofthe mixing housing, coaxial with the housing. This especially contributes to a strong turbulence ofthe media mixture.
• media could also be fed, through the mixing housing, in the other direction.
• figure 1 is a side view ofthe device, partly in section, and figure 2 is an end view ofthe device.
• 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 ofthe bearing housing. These three parts are connected to each other by flanges.
• a feed pipe 4 is welded at an opening 5 through the cylindrical wall 6 ofthe mixing housing.
• a revolvable rotor 7 is arranged inside the mixing housing 1 .
• the rotor has one rotor cross, with radial arms 8, at the outlet opening 9 ofthe housing 1 and a similar rotor cross 10 at the other end ofthe housing 1, and the ends ofthe arms 8 are connected to the ends ofthe arms ofthe rotor cross 10 by four axial bars 15 which sweep along the inside ofthe 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 ofthe bearing housing 2. End wall 12 is also, at the same time, the end wall ofthe 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 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 ofthe wall 6 against the centre ofthe housing 1. Furthermore the axial bars 15 can be designed slightly curved to support the feed ofthe media through the housing 1 forwards the outlet opening 9.
• the arms 8, ofthe rotor cross in the outlet opening 9, are twisted and/or curved causing a strong turbulence when the media is passing.
• one or several more rotor crosses can be arranged at the rotor 7 between the two which are shown in the drawing.
• the axial part ofthe 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.
• 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.
• the arms of the rotor crosses can be more or less than four.
• the ends ofthe arms can be connected by a circular reinforcement if increased rigidity ofthe rotor is desired.

Landscapes

• Mixers Of The Rotary Stirring Type (AREA)

Applications Claiming Priority (1)

Publications (2)

Family

ID=20401342

Family Applications (1)

Country Status (2)

• 1996
  • 1996-04-16 EP EP96920081A patent/EP0912235B1/de not_active Expired - Lifetime
  • 1996-04-16 DE DE69618249T patent/DE69618249T2/de not_active Expired - Fee Related

Non-Patent Citations (1)

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