EP2844938B1

EP2844938B1 - Aeration apparatus

Info

Publication number: EP2844938B1
Application number: EP13717954.5A
Authority: EP
Inventors: Kjell Inge HÅKONSEN
Original assignee: Mortensen Lars
Current assignee: Mortensen Lars
Priority date: 2012-05-04
Filing date: 2013-04-16
Publication date: 2019-03-20
Anticipated expiration: 2033-04-16
Also published as: NO335389B1; WO2013164186A1; NO20120508A1; EP2844938A1

Description

FIELD OF THE INVENTION

The present invention relates to an aeration apparatus for supplying air to a particulate material of variable particle size.

BACKGROUND

There exists a multitude of aeration apparatus for supplying air to a particulate material of variable particle size. An example is WO 2009/081373 , which teaches a process and apparatus for supplying air to products of variable particle size, for example, wood chips. The apparatus comprises an inlet, an outlet, a perforated conveyor belt that conveys wood chips from the inlet to the outlet, and a means for blowing hot air through the perforated conveyor belt and through the wood chips.
Furthermore, the aeration apparatus has a walled hopper, which effects the distribution of the particulate material onto the perforated conveyor belt. The apparatus further comprises a stationary or moving perforated plate located above the wood chips.
The disadvantage of the apparatus described above is that the particulate material is non-uniformly distributed along the conveyor belt, that is to say that the layer of particulate material has a different height in the longitudinal direction and the width direction of the conveyor belt. This results in the particulate material drying unevenly, since it dries faster where the layer is thin than where it is thick. During work on the present invention, it was found that moisture from particulate material in areas where the layer is thin evaporates, but that it condensates in the upper, thicker layers (when hot air is blown from below and upwards). This means that whilst the moisture is indeed reduced in the thinner layers, it is in fact increased in the thicker layers, which is particularly problematic in connection with low-temperature drying (below 110° C) where the object is an efficient, good end result.
The above apparatus is not capable of distributing the particulate material sufficiently uniformly, and this can in fact be seen from Fig. 1 in WO 2009/081373 .
FR 1233567 teaches another known aeration apparatus with a deflector which constitutes a part of a wall of a temporary storage means for the particulate material, and which effects distribution of particulate material on a conveyor belt through which hot air is blown.
US 3060589 teaches an apparatus for supplying air to particulate material, where the distribution of the particulate material is regulated by a clearance between an inclined table and an adjustable shutter. This apparatus will also not be capable of distributing the particulate material sufficiently uniformly, and this can be seen from Fig. 1 in this document too.
WO 2010/045897 teaches an apparatus for supplying air to particulate material, which uses a rotating belt for distributing particulate material onto a conveyor belt.
WO 00/31481 describes a method and apparatus for drying a material, especially wood particles, having moisture therein, comprising depositing the material to a selected depth onto a conveyor belt at the first end of a drying chamber. Heat is applied to the material as it is transported towards the opposite second end of the drying chamber, so that, adjacent the second end, the material forms essentially two layers, a first layer having a first level of moisture therein and a second layer having a second level of moisture therein.
US 4126946 describes a method for drying grain in which the grain is first heated to drive off a portion of the moisture as it passes along a belt, and the heated and partially dried grain is then discharged into a container or bin where the moisture in the centre of the kernels migrates towards the surface and the temperature becomes substantially uniform throughout. The grain is then discharged onto a second belt where it is first heated to drive off a substantial part of the moisture remaining in the grain and then is cooled before it is discharged.
US 4253825 teaches a grain dryer comprising a plurality of horizontal conveyor belts arranged above one another and in staggered relationship so that grain delivered at one end of the upper conveyer belt will drop onto the lower conveyer belt when it gets to the other end of the upper conveyor belt and will then travel along the lower conveyor belt in the opposite direction before being discharged. Hot air is supplied by a hot air generator through conduits to a position below and along each of the conveyer belts, passes upwardly through the conveyor belts, which are formed of wire mesh, and through the grain thereon and is extracted through discharge conduits above the conveyor belts.
US 2 623 676 describes a pan filling machine where shallow pans are filled with a layer of granular material of uniform thickness.
US 1 723 917 describes an apparatus for drying a material in the form of an apron dryer.
One of the reasons the above documents are not capable of distributing the particulate material sufficiently uniformly is that moist particulate material will clump together.
The object of the present invention is to provide an apparatus for supplying air, especially hot, dry air, to a particulate material of variable particle size, in particular particulate material in the form of wood chips. A further object is to provide an apparatus which obtains an airy and uniform, preferably horizontal distribution of particulate material at the right height in the longitudinal direction and width direction of the conveyor belt so as thereby to prevent condensation and evaporation of the same water several times.
The object is also to provide an apparatus which during the aeration process is capable of adjusting for changes in volume of the particulate mass as a result of shrinkage and rearrangement, so as thereby to prevent problems of excess or insufficiency of mass.

SUMMARY OF THE INVENTION

The above objects are solved by means of the present invention in the form of an aeration apparatus for supplying air to a particulate material of variable particle size according to claim 1, which comprises:

an inlet through which the particulate material is admitted;
an outlet from which the particulate material exits;
a perforated conveyor belt for conveying the particulate material from the inlet to the outlet;
an air supply means for supplying air to the particulate material through the perforated conveyor belt;
a storage means for temporary storage of the particulate material between the inlet and the perforated conveyor belt;
a distribution means for distributing the particulate material to the perforated conveyor belt;

a movable blade arranged at a height above the perforated conveyor belt;
a drive means configured to move the movable blade back and forth in the longitudinal direction of the blade;

In an aspect, the distribution means comprises a sensor for measuring the amount of particulate material in the storage means, the distribution means being configured to adjust the height of the movable blade above the perforated conveyor belt based on the measured particulate material.
In an aspect, at least portions of the lower part of the movable blade extend into the storage means under a proximal internal wall of the storage means.
In an aspect, the proximal internal wall of the storage means has an adjustable height above the perforated conveyor belt.
In an aspect, the lower part of the movable blade has teeth.
In an aspect, a first plurality of the teeth are angled or bent at an angle α = 20 to 90° out from the vertical position towards the storage means, and a second plurality of the teeth are angled or bent at an angle β = 20 to 90° out from the vertical position away from the storage means.
In an aspect, the movable blade is provided in the width direction of the perforated conveyor belt.
In an aspect, the aeration apparatus is a drying apparatus for drying particulate material, where the air supply means is provided for supplying hot, dry air to the particulate material and where the particulate material is wood chips.

DETAILED DESCRIPTION

Embodiments of the present invention will be described in detail below with reference to the following attached figures, wherein:

Fig. 1 illustrates distribution of particulate material on a conveyor belt in accordance with the prior art;
Fig. 2a illustrates an aeration apparatus in a lateral view;
Fig. 2b illustrates a section of the embodiment in Fig. 2a from above;
Fig. 3 illustrates a detail of the aeration apparatus in Fig. 2a;
Fig. 4 illustrates an embodiment of the movable blade in Fig. 3 seen transverse to the direction of travel (A) in Fig. 3;
Figs. 5a, 5b and 5c illustrate alternative embodiments of the movable blade in Fig. 4 in a lateral view;
Fig. 6 shows an embodiment of the invention;
Fig. 7 shows an alternative embodiment of the invention;

Reference is now made to Fig. 1, which shows an aeration apparatus 1 for supplying air to particulate material 2 of variable particle size that is based on principles in accordance with the prior art.
By "particulate material of variable particle size" is meant here whole, crushed, chopped or pelletized material of wood, grain, beans, herbs, berries, fruit, vegetables, or other suitable particulate material.
The aeration apparatus 1 comprises an inlet 3 through which moist particulate material is admitted to the aeration apparatus 1 and an outlet 4 through which dried particulate material exits the aeration apparatus 4.
It should be noted that "moist" and "dried" here are relative terms; by "dried" is meant that the particulate material 2 is dryer than the particulate material that was admitted via the inlet 3. The embodiment shown in Figs. 2a and 2b is dimensioned such that wood chips may typically have a relative moisture of about 40% at the inlet 3 and a relative moisture of about 10% at outlet 4.
The aeration apparatus 1 further comprises a perforated conveyor belt 5 for conveying the particulate material from the inlet 3 to the outlet 4. It should be noted that only the inlet side of the conveyor belt 5 is shown in Fig. 1, that is to say, the side on which the particulate material comes from the inlet 3 onto the conveyor belt 5 (right-hand side in Fig. 1). The outlet 4 is only indicated in Fig. 1 as the end of the conveyor belt 5 (left-hand side in Fig. 1).
An air supply means 6 is provided for supplying hot air to the perforated conveyor belt 5 and to the particulate material 2. In the embodiment 2 shown in Figs. 2a and 2b, hot, dry air is blown from below and up through the perforated conveyor belt and the particulate material 2, and moist air is drawn off or otherwise removed from the area above the particulate material 2.
The aeration apparatus 2 further comprises a storage means 7 for temporary storage of the particulate material 2 between the inlet 3 and the perforated conveyor belt 5. This is desirable to ensure that the conveyor belt is continuously covered by particulate material - if the conveyor belt becomes completely empty of the particulate material at some points, a great deal of the hot air will pass through at precisely these points, thereby rendering the drying less efficient. Thus, this storage means 7 can be termed a sort of distribution means 10a for distributing the particulate material 2 to the perforated conveyor belt 5.
The aeration apparatus 1 may comprise a plurality of conveyor belts 5 provided in series. That is to say that after the outlet of a first conveyor belt particulate material falls into a temporary storage means 7 and is subsequently distributed onto a second conveyor belt. As the particulate material 2 falls, a so-called rearrangement of the particulate material takes place, which makes the drying on the next conveyor belt more efficient, since clumps of chip material will break up, allowing more air to come in between the individual particles.
The elements described above in connection with Figure 1 are regarded as known and will not be described in more detail.
The aeration apparatus 1 in accordance with the present invention is particularly suitable for particulate material in the form of wood chips. Furthermore, the aeration apparatus 1 is particularly suitable for supplying hot, dry air to wood chips with the object of drying the wood chips such that they are well suited as biomass fuel.
Reference is now made to Figs. 2a and 2b. These figures show an aeration apparatus 1 which comprises two perforated conveyor belts 5a and 5b. Particulate material 2 is filled at the top of the aeration apparatus 1 through the inlet 3 into a first storage means 7a and is distributed on the first conveyor belt 5a with the aid of a first distribution means 10a. The particulate material is supplied with air and dried whilst it is conveyed in direction A on the first, uppermost conveyor belt 5a. At the end of the first conveyor belt, the particulate material falls into a second storage means 7b and is distributed on the second, lower conveyor belt 5b with the aid of a second distribution means 10b. The particulate material is supplied here with more air and is thus dried further whilst being conveyed in direction A on the second conveyor belt 10b.
The air supply means 6 is also shown in Fig. 2a with its air inlet 6a and air outlet 6b.
Reference is made to Fig. 2b, which shows the conveyor belt 5 with the particulate material 2 seen from above. The direction of travel of the conveyor belt 2 is indicated by the arrow A. The width direction, or transverse direction, of the conveyor belt 2 is indicated by the arrow B. The direction at right angles to the arrows A and B indicates the vertical direction H above the conveyor belt 5.
Reference is now made to Fig. 3. This figure contains a number of technical features that have been assigned the same reference numeral as in Fig. 1, and these technical features will not be described in detail here.
The distribution means 10 here comprises a movable blade 11 arranged at a height h1 above the perforated conveyor belt 5. The movable blade 11 is provided downstream of the storage means 7.
The distribution means 10 also comprises a drive means 20 configured to move the movable blade 11 back and forth in the longitudinal direction L of the blade (see Fig. 4). In a preferred embodiment, the movable blade 11 is provided in the width direction B of the perforated conveyor belt 5, i.e., the longitudinal direction L of the blade is oriented parallel to the width direction B of the conveyor belt. The length of the blade 11 is preferably as long as or a little longer than the width of the conveyor belt. When the perforated conveyor belt 5 is oriented vertically, the movable blade 11 is also oriented in a vertical position. Furthermore, a lower part 13 of the movable blade 11 is provided for contact with the particulate material for distribution thereof.
Fig. 4 shows a first embodiment of the movable blade 11. The movable blade 11 here comprises teeth 12 in a lower end 13 of the blade. The teeth may be pointed or curved. Furthermore, the blade 11 here is straight, i.e., the lower part 13 points straight down. An alternative embodiment is shown in Fig. 5a where a lower part 13 of the movable blade 11 is angled or bent at an angle α = 20 - 90° out from the vertical position in a direction towards the storage means 7. Fig. 5b shows an alternative embodiment where a lower part 13 of the movable blade 11 is angled or bent at an angle α = 20 - 90° out from the vertical position in a direction away from the storage means 7. Fig. 5c shows yet another alternative embodiment, and here a first plurality of the teeth 12 are angled or bent at an angle α = 20 to 90° out from the vertical position towards the storage means 7 and a second plurality of the teeth 12 are angled or bent at an angle β = 20 to 90° out from the vertical position away from the storage means 7.
The distribution means 10 is configured to adjust the height h1 of the movable blade 11 above the perforated conveyor belt 5. This can be done with the aid of the drive means 20, or it can be done using a separate drive unit that moves both the blade 11 and the drive means 20 vertically.
Fig. 3 shows that the distribution means 10 may comprise a sensor 21 for measuring the amount of particulate material 2 in the storage means 7. The distribution means 10 is configured to adjust the height h1 of the movable blade 11 above the perforated conveyor belt 5 based on the measured amount of particulate material 2. The sensor 21 is therefore connected to the drive means 20, or alternatively the separate drive unit.
If optical sensors are used, an upper and a lower sensor will normally be used, or alternatively even more sensors. If the amount of particulate material is above the level of the upper sensor, the blade must be raised to get chip material through faster whilst distributing particulate material at a higher height h, and if the amount of particle material is lower than the lower sensor, the blade must be lowered to be able to distribute the particulate material at a lower height h.
Reference is now made to Fig. 6. In this embodiment, the distribution means 10 is a movable blade 11 of the type shown in Fig. 5a, where the teeth 12 on the blade 11 are angled or bent at an angle α = about 45° out from the vertical position towards the storage means 7. In this embodiment, at least portions of (that is to say, the lowermost or outermost portion) of the lower part 13 of the movable blade 11 extend into the storage means 7 beneath the proximal internal wall 7a of the storage means 7. By "proximal" is meant the internal wall 7a of the storage means 7 that is closest to the blade 11. Here, the blade 11 ensures both a uniform distribution of the particulate material on the conveyor belt 5, and also contributes to a steadier flow of the particulate material out of the storage means 7.
In the embodiment in Fig. 6, the proximal internal wall 7a of the storage means 7 also has an adjustable height h2 above the perforated conveyor belt 5. Furthermore, the distribution means 10 may be fastened to the outside of this wall 7a. Rough adjustment of the height of the particulate material can thus be effected by vertical adjustment of the wall 7a itself, whilst fine adjustment of the height of the particulate material can be effected by a vertical adjustment of the blade 11. A uniform distribution of the particulate material can thus be obtained even though the amount of particulate material fed to the inlet 3 varies.
In Fig. 6, too, the adjustment (the rough adjustment and/or fine adjustment) can take place automatically with the aid of a sensor, as described above.
Reference is now made to Fig. 7. In this embodiment, the distribution means 10 comprises a first movable blade 11, as described in connection with the above reference to Fig. 6, and a second movable blade 11 as described above with reference to Fig. 5c and Fig. 3. As shown in Fig. 7, both blades 11a, 11b are attached to a common drive means 20, the first blade 11a extending into the storage means 7 and the second blade being provided downstream relative to the first blade. The drive means 20 is used for fine adjustment of the height of the particulate material, whilst the wall 7a is vertically adjustable and attached to the distribution means 10 and is used for rough adjustment.
In the above description, the aeration apparatus 1 is a drying apparatus for drying particulate material 2, where the air supply means 6 is provided for supplying hot, dry air to the particulate material 2 and where the particulate material 2 is wood chips. However, the aeration apparatus can also be used for cooling particulate material of variable particle size, such as pellets or the like. In such cases, the air supply means 6 is provided for supplying cold air to the particulate material 2.

Claims

An aeration apparatus (1) for supplying air to a particulate material (2) of variable particle size, comprising:
- an inlet (3) through which the particulate material is admitted;

- an outlet (4) from which the particulate material exits;

- a perforated conveyor belt (5) for conveying the particulate material from the inlet to the outlet;

- an air supply means (6) for providing air to the particulate material (2) through the perforated conveyor belt (5);

- a storage means (7) for temporary storage of the particulate material (2) between the inlet (3) and the perforated conveyor belt (5);

- a distribution means (10) for distributing the particulate material (2) to the perforated conveyor belt (5);
where the distribution means (10) further comprises:
- a movable blade (11; 11a, 11b) arranged at a height (h1) above the perforated conveyor belt (5);
wherein the distribution means (10) is configured to adjust the height (h1) of the movable blade (11) above the perforated conveyor belt (5); the movable blade (11) is oriented in a vertical position, a lower part (13) of the movable blade (11) being provided for contact with the particulate material and characterized in that the distribution means further comprises a drive means (20) configured to move the movable blade (11; 11a; 11b) back and forth in the longitudinal direction (L) of the blade and in that the lower part (13) of the movable blade (11) is angled or bent at an angle α = 20 to 90° out from the vertical position towards the storage means (7), wherein at least portions of the lower part (13) of the movable blade (11) extend into the storage means (7) beneath a proximal internal wall (7a) of the storage means (7).
An aeration apparatus in accordance with claim 1, wherein the distribution means (10) comprises a sensor (21) for measuring the amount of particulate material (2) in the storage means (7), and wherein the distribution means (10) is configured to adjust the height (h1) of the movable blade (11) above the perforated conveyor belt (5) based on the measured amount of particulate material (2).
An aeration apparatus in accordance with claim 1, wherein at least portions of the lower part (13) of the movable blade (11) extend into the storage means (7) under a proximal internal wall (7a) of the storage means (7).
An aeration apparatus in accordance with one of the preceding claims, wherein the proximal internal wall (7a) of the storage means (7) has an adjustable height (h2) above the perforated conveyor belt (5).
An aeration apparatus in accordance with claim 3, wherein the lower portion (13) of the movable blade (11) comprises teeth (12).
An aeration apparatus in accordance with claim 5, wherein a first plurality of the teeth (12) are angled or bent at an angle α = 20 to 90° out from the vertical position towards the storage means (7) and a second plurality of the teeth (12) are angled or bent at an angle β = 20 to 90° out from the vertical position away from the storage means (7).
An aeration apparatus in accordance with one of the preceding claims, wherein the movable blade (11) is provided in the width direction (B) of the perforated conveyor belt (5).
An aeration apparatus (1) in accordance with one of the preceding claims, wherein the aeration apparatus (1) is a drying apparatus for drying particulate material (2), the air supply means (6) being provided for supplying hot, dry air to the particulate material (2) and the particulate material (2) being wood chips.