Abstract:
A premasher ( 1, 100 ) for beer brewing processes, having a downpipe ( 2 ) for a stream of grist and an inlet opening ( 9 ) for mash water which opens into the downpipe ( 2 ). In order to improve the mixing degree of mash water and grist, the inlet opening ( 9 ) has associated therewith a turbulence-generating flow guide means ( 15, 25 ).

Description:
REFERENCE TO RELATED APPLICATIONS 
   This disclosure claims the benefit of the filing date of International Application No. PCT/EP02/14173, having an international filing date of Dec. 12, 2002, which designated the United States of America, and this disclosure is the United States national stage of that international application. This disclosure further claims priority to European patent application EP 02001698.6, filed Jan. 24, 2002. 
   1. Field of the Invention 
   The invention relates to premasher used for beer brewing. 
   2. Background of the Invention 
   In beer brewing processes, the rough-ground malt must be mixed with water, i.e. mashed, so as to convert insoluble substances, such as in particular starch, into soluble substances, in particular sugar. For obtaining a good yield and in order to allow unproblematic further processing, it must be guaranteed that the grist is mixed completely with water and that the formation of clots is prevented. In addition, there is the problem of very intensive dust formation, primarily in cases where grist and water are fed into the mash tub via a downpipe. The fine dust rising in the course of this process adheres to structural components and, together with water vapour, it forms sticky residues that can only be removed with great effort, especially in cases in which a so-called powder grist containing an extremely high percentage of powder is used, this type of grist being obtained e.g. from a hammer mill. Hence, so-called premashers are already used nowadays; up to now, such premashers have only been composed of a downpipe which serves to feed the grist and which is attached to the top of the mash tub, and of a water inlet opening, so that the grist and the water can already be brought into contact with one another in the downpipe before they enter the actual mash tub. The water is fed through an inlet opening, which is either provided at the center of the downpipe or extends in the form of an annular opening through the wall of said downpipe. The water is thus discharged substantially radially to the downpipe, immediately after having left the inlet opening, but, due to the flow velocity of the grist in the downpipe, it is then deflected in the form of a parabola in the direction of the flow of grist. However, it turned out that not even the use of this premasher resulted in an optimum mixing degree between water and grist, since the grist was enveloped by a kind of water veil and since this had effect that the grist and the water were not thoroughly mixed. 
   It is therefore the object of the present invention to improve the mixing degree of grist and mash water. 
   SUMMARY OF THE INVENTION 
   It was possible to find out that, on the basis of the turbulences produced in accordance with the present DISCLOSURE, the mixing degree of grist and mash water increases extremely and that dust formation does not take place, not even if hammer-mill grist containing a high percentage of powder is used. 
   Turbulences are preferably produced by a tangential component of the mash water. In this way, a certain rotational flow is superimposed on the radial flow, with the rotational flow causing in a particularly effective manner higher relative speeds between the grist and the mash water, whereby the mixing degree is markedly increased and the dust particles are bound immediately. 
   The tangential component is produced in a structurally simple way by deflector surfaces. 
   Furthermore, measures can be provided, which influence the flow velocity of the grist and of the water. One of these possibilities is, for example, a reduction of the width of the flow cross-section of the downpipe; said reduction of width can be effected by certain measures described in the disclosure and rotational interference elements which act to intensify the turbulences still further. 
   Another measure is seen in that the inlet opening for the mash water is implemented as a nozzle in such a way that the speed of the mash water is increased above an average speed. 
   An increase in speed and the resultant suction effect can additionally be supported by the displacer for the grist, which is provided in the area of the inlet opening for the mash water. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     In the following, embodiments of the present invention will be explained making reference to the drawings, in which: 
       FIG. 1  shows a schematic representation of a first embodiment of a premasher according to the present disclosure in a longitudinal section, 
       FIG. 2  shows a schematic top view of the area of the inlet openings of the premasher according to  FIG. 1 , 
       FIG. 3  shows an enlarged detail in the area of the inlet opening of the premasher according to  FIG. 1 , 
       FIG. 4  shows a schematic representation of a second embodiment of a premasher according to the present disclosure in a longitudinal section, 
       FIG. 5  shows a representation, similar to  FIG. 2 , of the premasher according to  FIG. 4 , and 
       FIG. 6  shows an enlarged detail in the area of the inlet opening of the premasher according to  FIG. 4 . 
   

   DETAILED DESCRIPTION 
     FIG. 1 to 3  show a first embodiment of a premasher  1  according to the present invention, comprising a downpipe designated generally by reference numeral  2 ; the wall  3  of said downpipe  2  is arranged such that its axis  3   a  extends perpendicular and it is adapted to be connected via a first fastening flange  4  to the discharge pipe of a grist container, a delivery line or the like, and via a second flange  5  to a mash tub in such a way that the grist will fall through the downpipe  2  in a vertical, gravity-conditioned flow A. 
   The wall  3  of the downpipe  2  comprises an area  6  having a first internal width D 6  and defining an upper area when seen in the flow direction A and an area  7  having an internal width D 7  and defining a lower area when seen in the flow direction A. D 6  is larger than D 7  and merges with D 7  via a transition surface  8 . The transition surface  8  extends obliquely towards the center line  3   a  at an angle α relative to the flow direction A. The angle α is an angle of approx. 30° to 50°, preferably approx. 40° to 45°. 
   The area  7  of the wall  3  has a length L which corresponds preferably to at least 2×D 7 . In said area  7 , elements  19  projecting towards the center line  3   a  and into the flow of material are provided in spaced relationship with the transition surface  8 ; the purpose for which said elements are used will be explained hereinbelow. 
   In the preferred embodiment, the areas  6  and  7  have a circular cross-section and consist of commercially available tubular portions, the difference between the internal tube diameters of said areas  6  and  7  being preferably standardized. 
   A gap-shaped inlet opening  9  for mash water opens into the interior of the downpipe  2  at a location between the transition surface  8  and the circumference of the wall  3 , said gap-shaped inlet opening  9  extending along the entire circumference of said wall  3 . The inlet opening  9  communicates with a water distributing chamber  10  formed by a jacket  11  arranged in said upper area  6  in spaced relationship with the wall  3 . The water distributing chamber  10  extends over the whole outer circumference of the wall  3  in said area  6  and over part of the axial length of said area  6 . A water supply line  12  opens into the distributing chamber  10 . 
   In the vicinity of the transition between the areas  6  and  7  of the wall  3 , a displacer  13  is arranged symmetrically about the center line  3   a , said displacer  13  being held by a holding means  14  in the flow path of the grist at a location above the inlet opening  9 . The displacer  13  is preferably formed as a flow guide body and, in the embodiment shown, it has the shape of a double cone. By means of said displacer  13 , the flow cross-section is reduced to an annular passage before or at the water inlet opening  9 , when seen in the flow direction A, and re-enlarged after the water inlet opening  9 , said annular passage having the annular width a. 
   As can especially be seen in  FIG. 3 , the inlet opening  9  has associated therewith a flow guide means  15  defined, in the present embodiment, by deflector plates  16  which stand on the transition surface  8  end on and which are directed away from the inlet opening  9 . The deflector plates  16  can also fulfill the function of a spacer between the area  6  of the wall  3  and the transition surface  8 . Each deflector plate  16  comprises two opposed, parallel deflector surfaces  16   a  and  16   b  and is arranged in such a way that it projects into the interior of the downpipe  2  and that the deflector surfaces  16   a ,  16   b  extend essentially parallel to the flow direction A and include with the diameters D 6  and D 7 , respectively, an angle β. In other words, the deflector plates  16  are arranged such that the deflector surfaces  16   a ,  16   b  are located approximately on a spiral surface extending towards the center line  3   a ; “approximately” means here that the deflector surfaces  16   a ,  16   b  themselves need not necessarily be curved, but are preferably straight surfaces. The angle β is preferably an angle of approx. 30°. 
   By means of the deflector surface  16   a , the mash water flowing in direction B through the inlet opening  9  and onto the transition surface  8  is deflected into a direction C parallel to the deflector surface  16   a , which has a tangential component T. This has the effect that the mash water is forced into a kind of rotation path and generates turbulences which markedly improve the mixing ratio between grist and mash water. 
   As can especially be seen in  FIG. 2 , the flow guide means  15  comprises a plurality of deflector plates  16  which are distributed around the annular gap-shaped inlet opening  9 , preferably at regular angular intervals  6  of preferably 45°. The second deflector surface  16   b  of the deflector plate  16  decelerates the tangential or circumferential movement of the incoming water and deflects said water again towards the center line  3   a.    
   Due to the fact that the transition surface  8  is inclined at the angle α, also said transition surface  8  acts as a deflector surface with a radial component so that the mash water will reliably arrive at the interior of the downpipe  2 . 
   The generation of these turbulences is additionally supported by an inlet opening  9  which is implemented as a nozzle, i.e. which has a suitably reduced size h, in this case a reduced gap width, which guarantees that the speed of the water introduced will increase above the normal average speed of 2 m/s. 
   In the upper area  6  of the downpipe  2 , an additional connection  17  is provided, which is implemented as a conventional spray-type cleaning head, but which is also able to supply water into the interior of the grist stream in the vicinity of the center line  3   a  thereof. 
   When the premasher  1  according to the present invention is in operation, the grist falls in a constant stream in the direction of the arrow A through the downpipe  2  and hits against the displacer  13 . The displacer  13  deflects the grist stream in the direction of the transition surface  8  and in the direction of the water inlet opening  9 . By means of said water inlet opening  9  and by means of the transition surface  8 , which is implemented as a deflector surface, and the deflector surfaces  16   a ,  16   b , the mash water is fed at an increased speed in such a way that turbulences are formed, said turbulences guaranteeing that the grist and the mash water will be thoroughly mixed. Simultaneously, a certain rotational movement is generated, which will continue when the mixture of grist and mash water enters the second area  7  having a reduced diameter. Due to the longer length L and the smaller diameter, said second area  7  acts as a mixing path that intensifies the mixing, and due to the plates  19 , which act as rotation interference elements, a substantially laminar flow is re-established. The reduced interior width will additionally cause an increase in speed and, consequently, a decrease in pressure. Hence, a certain suction effect is produced, which is intensified still further by the displacer  13  arranged directly in front of the inlet opening  9 . The grist entering the mash tub will then be a grist which has already been thoroughly mixed with water and which will neither make dust nor tend to clot. 
     FIG. 4 to 6  show a further embodiment of a premasher  100  according to the present invention, which, with the exception of the details described hereinbelow, is identical with the premasher  1  according to  FIG. 1 ; identical or comparable components are designated by identical reference numerals and are not explained once more. 
   The premasher  100  differs from the premasher  1  insofar as the flow guide means  25  has been modified in comparison with the flow guide means  15 . However, also the flow guide means  25  comprises a plurality of deflector plates  26  having two deflector surfaces  26   a ,  26   b  which are arranged in parallel. Also the deflector surfaces  26   a ,  26   b  are tilted by the angle β relative to the radial direction, but they are additionally inclined by the angle δ relative to the horizontal. It follows that the deflector surfaces  26   a ,  26   b  are located approximately on a spiral conical surface around the center line  3   a , the tip of said conical surface being directed upwards. “Approximately” means here that the deflector surfaces  26   a ,  26   b  do not follow the curvature of the spiral conical surface, but extend along a straight line. 
   The effect produced by the flow guide means  25  is comparable to that produced by the flow guide means  15 , the difference being that, due to the inclination at the angle δ, the mash water will be spread more widely and bind dust particles, which are already present in the downpipe  2 , at an early stage, the grist being also deflected from the flow direction A with a tangential component about the center line  3   a , and this will, especially in the case of certain grist grades, support turbulence formation and thorough mixing. 
   As modifications of the embodiments described and shown hereinbefore, the turbulences can also be obtained by other measures which are known to cause turbulence flows. In addition, the tangential component can also be produced in that the inlet opening for the mash water is arranged at an oblique angle. When deflector surfaces are used for a change of direction of the mash water stream, said deflector surfaces can be provided on a great variety of deflector bodies and, in addition to the flat deflector surfaces described, curved or angled deflector surfaces may be used as well.