EP2503272A2

EP2503272A2 - Device for drying loose material

Info

Publication number: EP2503272A2
Application number: EP12160518A
Authority: EP
Inventors: Veikko Jolkin; Veijo Rönkkö
Original assignee: Finnomec Oy
Current assignee: Finnomec Oy
Priority date: 2011-03-21
Filing date: 2012-03-21
Publication date: 2012-09-26
Also published as: FI20110100A0; EP2503272A3

Abstract

The invention relates to a device for drying loose material, which device includes a cover structure (1), which is located around a duct (2), in which heated medium flows, and planes (3) located at a distance from each other for the material being dried, from which planes the material being dried is arranged to transfer from an upper plane onto a lower one during drying. In the device according to the invention, the cover structure is bearing-mounted and arranged rotatable in relation to the duct (2).

Description

The invention relates to a device for drying loose material according to the preamble of claim 1.
Loose material here refers to moist material, which is material of relatively small size being dried for storage and stowage. Such materials are e.g. material used as fuel, e.g. wood, such as wood chips or equivalent fuel manufactured of wood material. Additionally, material being dried can be e.g. grain or other foodstuffs of suitable size and applicable for the purpose.
Conventionally, wood chips or equivalent wood materials have been dried by various devices. Such drying devices are, inter alia, drum dryers in which wood material is rotated during drying. Furthermore, there are different ventilation dryers, bed dryers, silo dryers and reversed current dryers. It is characteristic for all of these that chips are dried by a separate device and usually far from the target of use employing a separate heat source during drying. Then, there are several separate treatment steps and intermediate storing steps, which all increase working time and raise costs.
For drying loose material, there also exist such dryers in which heated air is blown through a duct in the middle of the device, the flowing air heats up the duct walls and the material being dried, which material is transferred in different ways in the device in relation to the duct during drying.
The object of the invention is to introduce a device for drying loose material by means of which disadvantages related to prior-art devices are eliminated. A particular object of the invention is to introduce a device for drying loose material, which provides efficient and cost-effective drying. A further object of the invention is to introduce a device for drying loose material in which drying utilises already existing devices.
The object of the invention is achieved with a device for drying loose material, which is characterised by what is presented in the claims.
The device according to the invention includes a cover structure, which is located around a duct, in which heated medium flows, and planes located at a distance from each other for material being dried, from which planes the material being dried is arranged to transfer from an upper plane onto a lower one during drying. It is characteristic of the device according to the invention that the cover structure is bearing-mounted and arranged rotatable in relation to the duct, and the device includes transfer elements for dropping the material being dried from a plane onto a lower one. When the cover structure is bearing-mounted and rotatable around the duct, the material being dried can be transferred from the planes effectively and controllably downwards from one plane onto another by means of the transfer elements. The structure is simple and cost-effective to manufacture and use.
The duct can be a chimney, an air-conditioning duct or some other duct suitable for the purpose. In the duct, heated medium flows, which can be air, some other gas mixture or liquid. When utilising a smoke flue (chimney) of the fuel combustion plant in question, the material being dried can be dried by the so-called lost heat which is conducted from the outer surface of the smoke flue to the device, and drying requires no exterior energy. Drying is efficient, cost-effective and safe. Furthermore, drying takes place very close to the end-use site of the fuel, which provides considerable advantages and savings. The dried material can be fed directly to a burner feed bin, whereby only the required quantity of material is dried and it cannot moisten again during storage.
In an advantageous embodiment of the invention, the planes include an opening or openings from which the material being dried is able to fall onto a lower plane. The shape and structure of the planes and the openings can vary considerably in the various embodiments of the invention. The planes can be of different sizes and the openings in them can be of different sizes and/or of different shapes on different planes. When the material being dried transfers and falls from one plane onto another, it will not be wasted during drying and the drying process occurs simply and cost-effectively.
In an advantageous further embodiment of the invention, the planes are attached on the outer surface of the duct. The duct is a fixed structure, whereby the planes will stay well in place, and the planes and the material being dried on them will not strain the rotatable structure.
In a third advantageous embodiment of the invention, there are transfer elements on the inner surface of the cover structure at a distance from each other, at the points of the planes in order to drop the material being dried onto a lower plane when rotating the cover structure. By means of the transfer elements, the material being dried can be dropped onto a next, lower plane efficiently. The shape and structure of the transfer elements can vary in different embodiments of the invention.
In an additional advantageous embodiment of the invention, the planes are attached on the inner surface of the cover structure and the transfer elements are attached on the outer surface of the duct at a distance from each other. Thus when rotating the cover structure, the transfer elements will move at the points of the planes and drop efficiently the material being dried onto a lower plane.
The invention will now be described in more detail with reference to the accompanying drawings in which

Fig. 1: shows a side view of an embodiment of a device according to the invention,
Fig. 2: shows a top view of the device according to Fig. 1,
Fig. 3: shows a vertical section A-A of the device according to Fig. 2,
Fig. 4: shows a cross section B-B of the device according to Fig. 3,
Fig. 5: shows a cross section of a cover structure of the device according to Fig. 1, and
Fig. 6: shows an inner structure of the device according to Fig. 1.

The device according to the figures includes a cover structure 1 which is located around a duct 2 and bearing-mounted and arranged rotatable in relation to the duct. The device is supported and bearing-mounted from its upper and lower edge to the duct and it includes a device (not shown in the figures) to rotate the cover structure. Additionally, the device pertains planes 3 being inside of it, located at a distance from each other for the material being dried, and the material being dried is arranged to transfer from an upper plane onto a lower one during drying. The device also includes a feed section being in its upper part, not shown in the figure. The material being dried is brought in a way known as such at the point of the device and dropped via the feed section to the device onto its first plane. The device is vertical or in a slightly oblique position in relation to the vertical direction, still such that the material being dried is able to fall from the plane onto the next lower plane. The device also pertains elements (not shown in the figures) to remove moist air from inside the device by sucking air from down upwards or to the sides. In the duct 2, heated medium flows according to the arrow from down upwards. The heat of the duct heats up the drying device being around it.
In devices according to the figures, the planes include an opening 4 or openings from which the material being dried is able to fall onto a lower plane. In the embodiment according to Fig. 6, the planes are only slightly over 180° of the circular arch and the lower plane is always on the other side of the structure than the upper plane. In some other embodiments, the size of the openings can vary and the plane can include two or more openings. However, the opening or openings of the upper plane are not at the point of the opening or openings of the next lower plane, whereby the material falling from the upper plane will stay on the surface of the lower plane.
In an embodiment according to the figures, the planes 3 are attached on the outer surface of the duct 2 and, on the inner surface of the cover structure 1, there are transfer elements 5 at a distance from each other, at the points of the planes in order to drop the material being dried onto a lower plane when rotating the cover structure. In this embodiment, the transfer elements are planar elements the lower edges of which are above the upper surface of the plane and, when rotating the cover structure, the lower edge of the transfer element transfers along the upper surface of the plane and at the same time transfers the material on top of the plane forward until it falls onto the next plane. The shape and structure of the transfer elements can be different in various embodiments of the invention.
When using the device, the material being dried is dried on each plane for a specific time depending on the material, its initial moisture and size and the temperature of the duct. Then, the cover structure is rotated, whereby the transfer elements transfer the material on top of the plane onto a lower plane and from the lowest plane out of the drying device. The rotation speed is adjusted by monitoring the progress of drying and by measuring the moisture and temperature of the material being dried. From the device, the dried material is able to fall from the opening of the lowest plane along a transfer plane 6 in the lower part of the device to the storage bin or directly to the feeding tank of the boiler. The drying process is started and stopped according to the boundaries in the storage bin or the feeding tank of the boiler. The drying device will always be run until empty before stopping it for reasons of safety.
In another embodiment of the invention, the planes are attached on the inner surface of the cover structure and, on the outer surface of the duct, there are transfer elements at a distance from each other, at the points of the planes in order to drop the material being dried onto a lower plane when rotating the cover structure in a similar way as described above.
The drying device shown in the figures is especially well suitable for drying fuel and particularly wood fuels, but the invention is not solely limited to these materials as it can be employed for drying various materials of relatively the same size.
The invention is not limited to the described advantageous embodiments, but it can vary within the scope of the inventive idea presented in the claims.

Claims

A device for drying loose material, which device includes a cover structure (1), which is located around a duct (2), in which heated medium flows, and planes (3) located at a distance from each other for the material being dried, from which planes the material being dried is arranged to transfer from an upper plane onto a lower one during drying, characterised in that the cover structure is bearing-mounted and arranged rotatable in relation to the duct (2).
A device for drying loose material according to claim 1, characterised in that the planes (3) include an opening (4) or openings from which the material being dried is able to fall onto a lower plane.
A device for drying loose material according to claim 1 or 2, characterised in that the planes are attached on the outer surface of the duct (2).
A device for drying loose material according to claim 3, characterised in that there are transfer elements (5) on the inner surface of the cover structure at a distance from each other, at the points of the planes in order to drop the material being dried onto a lower plane when rotating the cover structure (1).
A device for drying loose material according to claim 1 or 2, characterised in that the planes are attached on the inner surface of the cover structure.
A device for drying loose material according to claim 5, characterised in that there are transfer elements on the outer surface of the duct at a distance from each other, at the points of the planes in order to drop the material being dried onto a lower plane when rotating the cover structure.