| DK125494B | 1973-02-26 | |||
| SE130800A | ||||
| DK138406B | 1978-08-28 | |||
| DE323462C |
| 1. | Drier for the heating and drying of wet, comminu¬ ted materials, mainly organic materials, said drier comprising a stationary housing with a revolving, hollow axle or rotor (1) with inlet and outlet for a heating medium, and condensate thereof, and where the rotor has a number of annular drying elements (2) dis¬ posed at intervals and which are heated by the heating medium, c h a r a c t e r i z e d in that a number of lifting elements (4) are disposed around the circumfe¬ rence of at least one of the drying elements (2) . |
| 2. | Drier according to claim 1, c h a r a c t e r ¬ i z e d in that the lifting elements (4) are dis¬ posed between two consecutive drying elements (2) , and each lifting element is secured to the two drying elements. |
| 3. | Drier according to claim 1 or 2, c h a r a c t ¬ e r i z e d in that the lifting element consists of a supportplate part (7) and two securing parts (8) . |
| 4. | Drier according to claim 3, c h a r a c t e r ¬ i z e d in that the supportplate part (7) is a substantially rectangular or square metal plate, the plane of which is parallel with the axis of the ro¬ tor, but which forms an angle V between 0 and 75 , preferably between 30 and 60 , with a plane through the rotor axis. |
| 5. | Drier according to' any of the claims 1 4, c h a r a c t e r i z e d in that the drying elem ents (2) have holes (10) at regular intervals along their outer edges, and that the two securing parts (8) of the lifting elements (4) have holes (9) with the same interval along at least one edge. |
| 6. | Drier according to any of the claims 1 4, c h a r a c t e r i z e d in that the lifting ele¬ ments (4) are permanently secured to the drying ele¬ ments (2) , for example by means of welding. |
| 7. | Drier according to any of the claims 1 6, c h a r a c t e r i z e d in that adjacent lifting elements are disposed in a displaced manner from each other, to the same side along the outer periphery of the annular elements (2), so that the leading edges (11) of the supportplate parts extend along a sub¬ stantially helical line. |
| 8. | Lifting element for use in a drier according to any of the claims 1 7, c h a r a c t e r i z e d in that it consists of one piece (4) of stainless sstteeeell ppllaattee wwhhiicchh iiss bbeenntt aappjprox. 90 along two parallel bending lines (12) . |
| 9. | Lifting element according to claim 8, c h a r ¬ a c t e r i z e d in that the plate piece (4) is formed as a square or rectangular supportplate part (7) and two identical, triangular securing pieces (8) with the one side of the triangle comprising the bending line (12) . '. |
| 10. | Use of a drier according to any of the claims 1 7 for drying an organic, comminuted mass from which meat meal, bone meal or fish meal is produced. |
The invention relates to a drier of the- kind present¬ ed in the preamble to claim 1.
Such driers are known, for example from Danish Patent No. 138.406, where the drier's rotor is provided with helical cavities in the annular drying elements, which on the surface have completely smooth faces in contact with the material to be dried, so that it is difficult for said material to stick fast and reduce the efficiency of the drier. However, stationary clearing elements can be arranged to reach in between the drying elements, for example in the zone where the material to be dried is still very adhesive. Moreover, transverse or obliquely-positioned vanes can be disposed on the rotating drying elements them¬ selves, which help to move the material being dried forward towards the discharge opening for the dried product. Driers of this kind are used for the drying of fishmeal, comminuted offal, mash and similar pro¬ ducts, and are often designed for high performance, e.g. for the drying of 1 to 4 tons per hour.
The object of the invention is to improve driers of this kind, so that an improved drying and mixing dur¬ ing the drying is achieved, whereby the efficiency of the drier is increased.
This is achieved by constructing the drier according to the invention as described more closely and char¬ acterized in claim 1. The lifting elements li t the material being dried in portions, and tear any pos¬ sible lumps into pieces. The lifted material falls
down over the drying rotor, and is thus given more frequent contact with the heating surfaces. At the same time, a better stirring is thus achieved, so that the material being dried is mixed more thorough- ly, the result being a completely uniform product.
If the drier is constructed as characterized in claim 2, the lifting elements will sit in a particularly secure manner, in that the lifting elements can be fastened on two sides.
By way of example, the drier according to the inven¬ tion is constructed as characterized in claim 3, in that this provides further possibilities of achieving a solid mounting and securing of the lifting ele¬ ments.
The drier according to the invention can be construc¬ ted as characterized in claim 4, the result thus ach- ieved being that the lifted material is spread a lot during its fall down over the rotor, and thus comes into contact with the whole of the heating surface, while at the same time a great mixing effect is ach¬ ieved.
If the drier according to the invention is construct¬ ed as described more closely and characterized in claim 5, it is possible in a simple manner to secure the lifting elements with bolts and to replace them, for example if they are worn or defect, but one can also adapt the drier for another production where an¬ other number of lifting elements provide an optimum operation.
For other uses and constructions it has proved ' advan¬ tageous to secure the lifting elements according to the invention as characterized in claim 6.
By constructing the drier according to the invention as characterized in claim 7, one can determine how quickly the material being dried shall travel for¬ wards in the drier and, if there is a need for this, the lifting elements can be disposed in such a manner that the material being dried remains longer in one zone than in another. A further possibility is thus achieved of being able to set the drier precisely for the raw materials to be dried. The consumption of energy is hereby optimized, so that the drier accord- ing to the invention uses the least possible thermal energy for the process without any adverse affect on the speed of production.
The lifting element according to the invention is preferably constructed as characterized in claim 8. The lifting element achieved hereby is robust but still inexpensive, and can be produced in a simple manner from plate material with sufficient strength and wear characteristics. If the lifting element ac- cording to the invention is constructed as character¬ ized in claim 9, an extremely simple construction is achieved which can be stamped out in one operation, e.g. so that the completely finished lifting element is complete with securing holes. Furthermore, if the plate piece is formed symmetrically and securing holes are provided in two free edges in both triang¬ ular portions, the lifting element can be turned when the leading edge is worn, hereby further increasing its lifetime.
The drier according to the invention has proved to be particularly well-suited for use in the production of meat meal, bone meal and fish meal, and. great im¬ provements have been achieved hereby, both of a tech- nical as well economic nature.
The invention will now be described in closer detail with reference to the drawing, which shows a prefer¬ red embodiment of the drier according to the inven- tion, and where
fig. 1 is a perspective drawing of a part of a rotor with lifting elements, which at the same time transport the material to be dried forwards,
fig. 2 shows the same as fig. 1, but where the lifting elements are disposed in such a way that the material to be dried is moved in the opposite direction, and
fig. 3 shows a lifting element before the bend¬ ing along the bending lines.
Figs. 1 and 2 of the drawing show a hollow rotor axle 1 with a number of annular elements 2 in which there are helical heat channels 3, these being connected to a heat source, e.g. a steam generator, through pipes in the hollow axle 1. The axle 1 with the drying ele- ment 2 rotates as shown by the arrow 5. Around the rotor is disposed a not-shown stationary housing with filling opening, discharge opening, possibly a heat jacket and inspection hatch, cleaning hatch etc.
The arrow 6 in fig. 1 shows the normal direction of transport through the drier from the filling opening to the discharge opening. On the drying elements 2, or more correctly between two consecutive drying el- ents 2, are disposed a number of lifting elements 4 with uniform distance around the circumference, for example eight lifting elements per intervening space. Each lifting element 4 consists of a support-plate part 7 and two triangular securing parts 8 which are fastened to the drying elements 2 by welding.
In fig. 2, the lifting elements 4 are shown secured with bolts (not-shown) through holes 9 in the triang¬ ular parts 8 of the lifting elements and holes 10 around the edge of the annular elements.
The lifting elements 4 can be mounted as shown in fig. 1, so that the individual lifting elements are parallel with the rotor axle, but where they are dis- posed slightly displaced from each other so that their leading edges 11 follow a substantially helical line. The lifting elements 4 here contribute towards the transport of the material in the direction of the arrow 6.
By disposing the lifting elements 4 as shown in fig. 2, where the helical line for the leading edges 11 of the lifting elements has a pitch which is opposite to that of fig. 1 , the lifting elements 4 will seek to transport the material in the direction of arrow 6, i.e. in the opposite direction to fig. 1. However, if one continues to load material to be dried through the filling opening, the disposal of the lifting el¬ ements as shown in fig. 2 will only slow down the
transportation, the result being that the material being dried will remain for a longer time in that zone in which the lifting elements are disposed as shown in fig. 2. One can hereby ensure that the mat- erial stays for a longer time in one zone than an¬ other zone in the drier.
The support-plate part 7 on the lifting element 4 has a rake in relation to the radial direction as shown by the angle V. This angle depends on the kind of material to be treated, but the angle V can also be different in different zones in the drier.
In fig. 3 is shown a lifting element 4 in its unfolded state, i.e. after it has been stamped out or blanked from a plate of stainless steel, but before it has been bent along the bending lines 12 to form a lif ¬ ing element. The lifting element consists of a rect¬ angular or square support-plate part 7 and two tri- angular securing parts 8 which have the bending line common with the support-plate part. If the lifting element 4 is to be of the kind which can be bolted firmly to the annular elements, it is provided with holes 9 in the triangular securing parts. If additio- nal holes are provided in the Opposite sides of the - triangular securing parts, the lifting element can be made symmetrical, thus providing two usable leading edges 11, so that one can turn the lifting element when the leading edge is worn.
Driers of the kind described rotate at about 7-12 revolutions per minute. Depending on the product to be dried, lifting elements are disposed in the zones where one can achieve the desired effect in the form
of better stirring and better efficiency, because one achieves more frequent and thus better contact be¬ tween the heating surfaces and the material being dried.