This invention relates to apparatus for heating and/or drying of the kind disclosed in the preamble to claim 1.

Such apparatus for the treatment of wet materials such as fishmeal, comminuted offal, mash from breweries and similar moist, glutinous materials of animal or vegetable origin are usally designed for high performances, i.e. for the drying of several tons of material at a time.

Such an apparatus is known from Danish patent no. 138.406, where the annular channels with hollow spaces for the heating medium in each drying element are in the form of a spiral for the through-flow of steam. The channels are spiral-shaped, because one can hereby more easily drive the condensate out of the channels, so that a good and continuous through- flow of steam is achieved. However, this form of channel gives rise to drawbacks from the point of view of production, the reason being that in practice the spiral shape is produced by a composition of circular sectors of suitably curved bands, in that these pieces of plate material are welded onto the disc-shaped rotor elements. This gives rise to difficult welding processes. Moreover, the ends of the bands must also be welded together, naturally all pressure-tight and generally executed in stainless materials.

The object of the invention is to provide an apparatus of the kind in question, but of such a con- figuration that the production is to a great extent made easier without hereby giving rise to other disadvantages.

This is achieved by configuring the apparatus according to the invention as disclosed and characterized in claim 1, whereby it is possible to feed several channels in parallel at one time, which gives a more uniform distribution of heat in the drying element and the possibility for the supply of more thermal energy than with the known con¬ structions. In practice, no problems arise with possible condensate if the heating is effected by steam. The heating can, however, also be carried out with, for example hot oil or the like. The supply of large amounts of thermal energy is of great im¬ portance if, for example, the comminuted material shall be boiled and possibly sterilized as quickly as possible.

With the new configuration of the apparatus, one is thus more freely disposed with regard to the positioning of the annular channels, in that they can be placed in any position over the whole of the drying element, i.e. in a one-sided or two-sided formation and closely at the side of each other, or with a distance between them. However, a very great supply of thermal energy can be achieved together with a uniform heating of the whole of the drying element if the drying apparatus according to the invention is configured as disclosed and characterized in claim 2.

When the apparatus according to the invention is con¬ figured as disclosed and characterized in claim 3, the production is simplified, the reason being that the welding on of channel parts is avoided. The drying elements are produced by providing a plate with suitable deformations so that the desired channel patterns arise.

The plates are preferably roundels, and it can be sufficient for one roundel in each pair to be de¬ formed for the formation of channels, but the apparatus according to the invention can also be con- figured as disclosed and characterized in claim 4, whereby the possibility is provided for channels of greater cross-sectional area and thus a greater supply of thermal energy, hereby increasing the capacity of the apparatus. This channel configuration also offers advantages from the point of view of production technology.

Since the annular channels in each drying element are not, in fact, of equal length, they do not have the same resistance to flow. In order to achieve a uni¬ form temperature distribution across each drying element, the channels can therefore be configured as more closely described and characterized in claims 5 and 6.

When the apparatus according to the invention is con¬ figured as characterized in claim 7, the whole of the welding operation involved in welding the channels onto the drying elements can be automated and carried out by simple welding robots, whereby a very even and uniform weld seam requiring the minimum of after- treatment is achieved.

By placing the channels on the apparatus according to the invention as disclosed and characterized in claims 8 and 9, the possibility is provided for a large number of channels on each drying element, and herewith a great supply of thermal energy.

By configuring the apparatus to the invention as disclosed and characterized in claims 10 and 12, changes can be made in the pattern of the stirring

and the heat distribution, e.g. depending on what kind of materials are to be handled. The con¬ figuration characterized in claim 12 provides optimum utilization of raw materials, in that the drying elements can be produced by the shearing of lengths of material which are then worked up in the formation of channels etc.

The apparatus according to the invention can also be configured as disclosed and characterized in claim

13, whereby the heating medium is supplied on the one side of the drying element and the return flow is on the other side, and thus the channels can be executed in an almost completely annular manner. This results in a very uniform heat distribution, and it is avoided that the supply channel and the return channel lie in each other's way during the welding operation. With some embodiments of the drying element, it can be advantageous that both the supply channel and the return channel are positioned on the same side, for example on the same side as the channels.

The invention will now be described in more detail with reference to the drawing, in that

fig. 1 shows a schematic longitudinal section in an apparatus according to the invention,

fig. 2 shows on a larger scale a plan view of a drying element according to a first em¬ bodiment of the invention,

fig. 3 shows a radial section of the drying element in fig. 2 seen in the direction III-III,

fig. 4 shows a plan view of a drying element

according to a second embodiment of the invention,

fig. 5 shows partly a radial section of the drying element in fig. 4 seen in the direction V-V,

fig. 6 shows a plan view of a drying element according to a third embodiment of the invention, and

fig. 7 shows partly a radial section of the drying element in fig. 6 seen in the direction VII- VII.

The apparatus 1 shown schematically in fig. 1 com¬ prises a stationary housing 2, possibly provided with a heat shroud, a filling opening 7 for the material to be dried, and a discharge opening 8 for the finish-dried material. The material introduced is dried by a heated, rotating rotor 3 with circular, plane drying elements 9 disposed at intervals. For the sake of clarity, the expression drying elements will be used when referring to the part 9, although for different applications it heats the material more or less.

When new, wet material is continously introduced into the apparatus, the material to be heated or boiled will migrate towards the discharge opening 8. The stationary housing 2 has not-shown discharge openings for the steam which is given off by the wet material during the drying.

The rotor 3 has a supply pipe 4 for the heating medium, e.g. steam, leading to a central pipe 11, and a discharge pipe 5 for steam plus a second discharge pipe 6 for condensate. The mode of operation is, in

fact, the same as that known, e.g. from Danish patent no. 138.406.

In figs. 2 and 3 is seen a drying element 9 on a larger scale and with two circular and concentric channels 10 which are concentric with the rotor 3, produced by arched, circular strips of stainless steel being welded to the drying element 9, which is a circular, plane disc, also of stainless steel.

The channels 10 are fed in parallel via a supply channel 12, which via a supply pipe 14 is connected to the central pipe 11. When the heating medium has passed around through the channels 10, it passes through holes 16 in the drying element 9 to a return channel 13 on the other side of the drying element, and via a return pipe 15 to the rotor 3. •

The channels 10 can have identical through-flow clearance, or be configured with different clearance and hereby regulate the through-flow resistance as desired. The through-flow resistance can also be regulated by inserting means such as throttle elements or the like. It is hereby ensured that the flow of heating medium through the channels 10 is as desired, e.g. uniform through-flow in all the channels.

In the example in figs. 2 and 3, the channels 10 are shown one-sided on the one side of the drying element 9. It will be obvious that the channels can also be disposed on both sides of the drying element 9, either opposite one another or staggered from one another. The channels can be disposed at intervals from one another or closely up against one another, all depending on how uniform the temperature distri¬ bution is desired to be and on how great a supply of

heat is required.

Figs. 4 and 5 show an example of a second embodiment of the drying element 9 , in that two roundels 17,18 are suitably deformed and joined together, e.g. by welding. In the shown example, both roundels are de¬ formed, but in practice it is sufficient for only one of the roundels to be deformed while the other is plane. In the shown example, the channels 10 are disposed immediately up against each other over the whole of the drying element 10 ^' , but naturally they can also be distributed with distance between them as shown in fig. 2.

In figs. 6 and 7 is shown a special embodiment of the drying element shown in figs. 4 and 5, in that the roundels 17 and 18 are provided with special channels 10 ^" , so that the drying element 9 ^' is given an even heat distribution, in that the innermost channels have less clearance than the outermost, e.g. evenly decreasing as shown, whereby the shorter the channels, the greater becomes the through-flow resistance.

In figs. 4-7 the supply means and the return means, e.g. pipelines, for the heating medium and possible condensate, are merely outlined. It will be obvious to those familiar with the art that supply pipes and discharge pipes for the channels 10 and 10 can be executed in many other ways than those outlined.

All of the shown channels 10,10 ,10 are shown with circular cross-sectional profile, but it will be obvious to those familiar with the art that innumerable other cross-sectional profiles can be used and produced with the same effect as the above- described, and without deviating from the basic

spirit of the invention.

In the examples in the drawing, all of the drying elements 9,9 ,9 are shown with a circular peripheral edge, and all channels 10,10 ,10 ^'' are similarly shown circular. It will be obvious to those familiar with the art that these parts can also have other geometric forms. For example, the drying element can be polygonal, possibly with a quadratic outer edge, and have circular channels or channels which follow the geometry of the edge. Nor is there anything to prevent a circular drying element from having channels with another geometry, for example polygonal.