DRYING INSTALLATION AND/OR METHOD FOR DRYING AN EMULSION

The present invention relates to a drying installation for drying a wet emulsion such as manure. The present invention also relates to a method for drying a wet emulsion. The present invention further relates to a method for applying a drying installation according to the present invention.

It is known to use manure for all manner of applications thereof. For a number of said applications it is advantageous if the manure can be provided in a dried state. An advantage hereof is that transport costs are for instance lower because the weight has been reduced by the drying. A further advantage is that the dried material is suitable for a number of applications for which the wet material is perhaps unsuitable. A problem of existing methods for drying manure is for instance that they are very time-consuming or do not achieve homogeneous drying.

In order to improve the drying of manure the present invention provides a drying installation for drying a wet emulsion such as manure, comprising:

- a drying conveyor for drying the emulsion during transport,

- a skimming member for skimming the emulsion to a thin layer, wherein the skimming member can be an individual unit or can be comprised in an emulsion feed device or co-acts herewith,

- a conveyor heating for heating the drying conveyor, wherein: - the drying conveyor is suitable for conducting heat to the emulsion from the underside, and

- the conveyor heating is arranged such that it supplies heat to the underside of the drying conveyor.

An advantage of such a drying installation is that the thin layer which is achieved by means of the skimming member can dry homogeneously. The supply of heat from the underside of the thin layer is advantageous here since evaporation energy can hereby be supplied to the thin layer. A relatively thin layer can dry relatively quickly. The problem of the moisture transport through the relatively thin layer is further resolved since the moisture only has to cover a short migration distance through the thin layer. A result is a layer of dry material with a homogeneity which is unprecedented for drying processes, for instance for manure. The dried substance can therefore have a relatively high solid content over the whole mass after a relatively short drying time. Further drying for instance, which is common in the prior art, is hereby no longer necessary.

In a first preferred embodiment the drying conveyor preferably comprises a flat sheet belt, preferably comprising a metal belt. A flat sheet belt is defined within the concept of this text as a belt comprising or formed by an infinite body from a metal sheet. An advantage of such a drying conveyor is that a good heat conduction from the conveyor heating to the emulsion for drying is realized. An efficient drying with a relatively short drying time can hereby be achieved. In a further preferred embodiment the conveyor heating comprises a contact surface for contact with the underside of the drying conveyor. An advantage hereof is that maximum heat transfer can be brought about by this surface contact. Such a surface contact must be seen as a heat-conducting contact between as much as possible of the material of the conveyor heating and the drying conveyor.

It must however be understood here that in preferred embodiments the use of for instance interruptions, in linear or other form, of this contact surface must also be deemed as forming part of the contact surface and/or may not be seen as an evasive design variation.

As seen in top view, the drying conveyor and the conveyor heating preferably share a heat transfer area over substantially the whole drying width of the drying conveyor. It hereby becomes possible to realize the greatest possible direct heat transfer, although it is also possible to reduce for instance the resistance with longitudinal grooves and the like. As seen in top view, the drying conveyor and the conveyor heating are preferably in substantially direct contact over the whole drying width of the drying conveyor, and preferably over as great a length as possible. The heat transfer is herein preferably realized over almost the whole length between the return members of the drying conveyor. An advantage hereof is that a maximum speed can be realized at a desired degree of drying and layer thickness.

In a further preferred embodiment the conveyor heating is preferably provided with a heat supply by means of heated water, gas heating and also electricity. The heat is however preferably obtained here by means of solar energy. The embodiment wherein the conveyor heating is provided with a heat supply by means of heated water can be combined herewith in efficient manner. The conveyor heating preferably comprises one or more flow channels with a heat generating wall on the top side with which a conveyor belt of the drying conveyor can be in direct contact. A maximum heat transfer to the conveyor belt is hereby possible at a minimum water temperature. Particularly this latter aspect is important in the use of

solar energy. In a further preferred embodiment the drying installation comprises an air drier for drying of drying air to be guided along the drying conveyor. The drier the air, the more efficiently the transfer of moisture from the emulsion to the air can be realized. The drying installation more preferably comprises a drying air heat exchanger for heating drying air to be guided along the drying conveyor. Use is made here of the fact that warm air can absorb more moisture than cooler air. The drying air heat exchanger preferably comprises separating walls and/or channels for further guiding of drying air. Heat can herein be supplied to the drying air by means of the separating walls or the walls of the channels. The heating energy necessary for this purpose is preferably also obtained from solar energy. Since relatively little energy is required to heat air, less advantage can be gained with this measure of this embodiment, but solar energy is nevertheless recommended. The separating walls and/or channels are preferably arranged for guiding drying air in downward direction. It is however also possible to supply the drying air to the drying conveyor from the side. It is recommended that the air is discharged laterally from the drying conveyor so that the air is as dry as possible throughout. A uniform supply of the drying air over the whole length of the drying conveyor is therefore advantageous.

For supply of the drying air the installation is preferably provided with an air guide member for guiding drying air in the direction of the drying conveyor. The drying air heat exchanger is preferably arranged here in the airflow in question. The same applies for the air drier. The drying installation preferably comprises air supply means and/or air exhaust means for forced guiding

of drying air for guiding thereof along the drying conveyor. The drying air is here preferably guided along the drying air heat exchanger and the air drier.

In a further preferred embodiment the drying installation comprises a pressure space which envelops at least the drying conveyor for the purpose of creating a relatively low pressure therein. The advantage hereof is that the transfer of moisture from the emulsion to the air is accelerated and/or improved. In a further preferred embodiment the drying installation comprises solar collectors such as flat-plate collectors for supplying solar energy to the drying conveyor or the drying air heat exchanger. An advantage hereof is that solar energy can be fed to the system in very efficient manner. This solar energy is preferably buffered in a thermally insulated heat buffer. It is also possible for instance to generate electrical energy by means of solar energy and supply this to the drying installation. A further aspect of the present invention relates to a method for drying air as according to one or more of the foregoing claims, comprising an emulsion preheating. A drying installation according to the present invention is preferably applied for this purpose. Such a method has similar advantages as specified in this document with reference to the installation.

Further advantages, features and details of the present invention will be described in great detail hereinbelow on the basis of several preferred embodiments which must not be interpreted as limitative, with reference to the accompanying figures, in which:

- Fig. 1 is a schematic side view of a first preferred embodiment according to the present invention;

- Fig. 2 is a schematic view of a second preferred embodiment according to the present invention.

A first preferred embodiment (Fig. 1) according to the present invention relates to a manure drying installation 1 for drying manure. The manure drying installation comprises a manure drying conveyor 2 comprising two drive rollers 16 which can be driven in per se known manner by means of a motor (not shown) . A stainless steel conveyor belt is arranged over transport rollers 16. Such a conveyor belt can also be manufactured from other materials, wherein the heat-conducting capacities are particularly important.

In the space defined by transport rollers .16 and the conveyor belt is situated a warm water reservoir 3 which is preferably suitable for transport of water therethrough. Suitable channels are preferably provided for this purpose on the inside of the reservoir. It is for instance possible to apply a number of lateral water feed inlets and outlets such that the warm water reservoir has as far as possible the same temperature along the whole length. Alternatively, it is possible to allow the warm water to flow in on one side and flow out on the other side, as seen in transverse direction. The water can be guided in longitudinal direction or in transverse direction through the warm water reservoir. It is also possible for the warm water reservoir to comprise zigzag channels for the water flow therethrough. It is further possible for the warm water reservoir to take up only a part of the height inside the conveyor belt. It is for instance possible to apply a relatively shallow warm water reservoir on the top side and a relatively shallow warm water reservoir on the underside. What is important is that sufficient energy is supplied for the conveyor belt

to be heated to the degree required in order to dry the manure .

The surface of the warm water reservoir situated against the surface of the underside of the transporting plane is preferably. A maximum heat transfer is hereby caused by means of conduction. It is equally possible here for a surface pattern to be applied, such as longitudinal ribs, protrusions or a combination thereof. In the transverse direction the conveyor belt is wholly supported by heat reservoir 3, so that energy can be transferred over the whole width of the conveyor belt. In addition to the energy supply by means of water it is also possible to supply energy by means of an electrical resistance with electrical energy or by means of a burner for combusting a fuel. The skilled person will of course be able envisage alternative methods of supplying energy within the scope of the present invention.

Use is made for drying purposes of drying air 11 which is forcibly guided through the device under the influence of exhaust fan 13. The higher the flow speed, the greater the amount of air which can absorb moisture. The incoming air is dried by means of an air drying unit so that the moisture-absorbing capacity hereof is increased. The air is then distributed over the whole length of the drying conveyor by means of a guide hood 5. The air is then guided through a heat exchanger 4 for the purpose of heating the drying air so that it can absorb more moisture when it flows over the drying conveyor and the wet emulsion located thereon. As can be seen, the air is guided through channels so that the air arriving above the drying conveyor is equally dry throughout for an effective absorption capacity thereof.

The manure is arranged by means of a manure dispensing unit 9 at the start of the conveyor belt, which rotates in the direction of arrows B. The manure dispensing unit is for instance able on the one hand to spray the manure onto the conveyor and on the other to spread and/or skim it. The result is a thin layer of manure with a layer thickness in the range of 0.1 centimetre to several centimetres. The optimal layer thickness depends on the transporting speed and the absorption capacity of the air, and for instance the applied temperature. The drying process can also be influenced by material properties of the emulsion. On the other side of the conveyor is situated a scraper unit 7 for scraping the dried manure from the conveyor belt. The dried manure then comes to lie in a conveyor belt for advancing dried material in the direction of a reservoir

12 for the dried manure.

The manure drying installation is preferably further provided with a pressure chamber 8 for holding the atmosphere therein at underpressure, whereby the absorption capacity of the air is increased, by means of which the drying process is accelerated.

Figure 2 shows a more comprehensive system for drying manure. Reference numerals are used here in accordance with figure 1 for similar components.

In this embodiment air is drawn by means of a fan

13 in the direction of arrows A through heat exchanger 4a in an animal accommodation, wherein outside air admitted through an air inlet 27 is heated by air present in the animal accommodation. The air which is thus preheated by the temperature of the animal accommodation is guided through a heat exchanger 4b for further heating of this air on radiator plates for hot water which is heated by

means of solar energy. For this purpose warm water is pumped out of a warm water reservoir by means of pump 26. The thus heated air is supplied to a pressure chamber 8 with four conveyor belts 2 therein for drying manure. The dried manure is discharged to a storage by means of conveyor belt 10. The manure for drying is situated initially in a central manure storage 31. It is pumped by means of pump 30 to a preheating heat exchanger 34, in which a heat-transfer coil 35 is situated. From heat exchanger 34 the manure is transferred to drying conveyor 2 in underpressure chamber 8. Heat exchanger 34 is provided with warm water from warm water reservoir 21 by means of pump 28.

The warm water reservoir is supplied with thermal energy by means of solar collector 22 and the circulation pump for the solar collectors 24.

The present invention is described in the foregoing on the basis of several preferred embodiments. Different aspects of different embodiments are deemed as described in combination with each other, wherein all combinations which can be made by a skilled person on the basis of this document must be included. These preferred embodiments are not limitative for the scope of protection of this document. The rights sought are defined in the appended claims.