EP0453462A1

EP0453462A1 - Method and apparatus for gathering sun radiation energy by driers, both method and apparatus for drying different materials

Info

Publication number: EP0453462A1
Application number: EP90901595A
Authority: EP
Inventors: Heikki Kalervo Oinas
Original assignee: Individual
Current assignee: Individual
Priority date: 1989-01-05
Filing date: 1990-01-03
Publication date: 1991-10-30
Also published as: WO1990007685A1; FI890041A; FI890041A0

Abstract

Méthode et appareil permettant de récupérer de l'énergie de rayonnement solaire en utilisant des séchoirs et méthode et appareil de séchage de différents matériaux. Le matériau (3) à sécher (3) sert, selon l'invention, de surface d'absorption, et l'énergie de rayonnement d'absorption, et l'énergie de rayonnement est utilisée pour sécher le matériau au-delà des parties en surface grâce à une circulation d'air à travers le matériau vers une aspiration selon la différence de pression appliquée grâce à un collecteur d'air placé sous le matériau et muni d'un ventilateur, lorsque le séchoir est sans toit fixe et/ou sans structure de parois (5), pour permettre le passage direct du rayonnement solaire à travers le matériau.Method and apparatus for recovering energy from solar radiation using dryers and method and apparatus for drying different materials. According to the invention, the material (3) to be dried (3) serves as an absorption surface, and the absorption radiation energy, and the radiation energy is used to dry the material beyond the parts on the surface thanks to an air circulation through the material towards a suction according to the pressure difference applied thanks to an air collector placed under the material and provided with a fan, when the dryer is without fixed roof and / or without wall structure (5), to allow direct passage of solar radiation through the material.

Description

Method and apparatus for gathering sun radiation energy by driers both method and apparatus for drying different materials

In cool driers drying air is additionally warmed in severe drying circumstances to improve water binding ability of the drying air.

Extra heat can be given by electrically or by fuel operating heat developers or by heat exchangers connected to heating systems. Equipment and method have also been developed to utilize sun radiation energy to heat drying air. A film pervious to sun rays, made for instance of plastic or glass, has been used, whereby drying air is taken from the space restricted by this film. Also structures pervious to air, f.ex. scale boards, lathes, veils etc. have been employed, through which the drying air is sucked, whereby these structures give a portion of the sun radiation energy collected to them to the drying air rinsing them. In all these solutions the drying air is encased to flow through the collection system before it comes to the material to be dried. A drawback of all known solutions discussed above is a relatively low efficiency. Because the radiation is collected using a medium and a portion of the sun radiation energy remains always in this medium in the range of 40-90%, the utilizable radiation energy is only 10-60%. One disadvantage is also caused by the collection structure with encasements increasing the costs and choking the air supply to the blower. With the simple and efficient method and equipment according to the invention a significant improvement is achieved in the collection of sun radiation energy, so that radiation goes directly to the material to be dried. The structure and operation of the method and the equioment is as follows: The drier has been built outdoors without any fixed roof (4) and/or wall structure (5) . The material (3) to be dried is therefore exposed to direct sun radiation ( 6) . The sun radiation energy directed to the material raises the temperature in the sur ace parts of the material according to its radiation effect and the absorption capacity of the material, evaporating water from the material at the area influenced by the radiation. The material distributes its raised heat content to the surrounding atmosphere increasing the air temperature. The relative humidity of the warmed air is reduced, and thus also the water binding ability or drying effect is improved according to the ollier table. Humidity in the surface parts has relatively rapidly been reduced to a state of equilibrium with the relative humidity in the surrounding atmosphere and the effect begins to retard the deeper layers. For utilization of the radiation it is advantageous to bring the radiation and the humidity to a direct contact with each other. This can be achieved by two ways:

1. Leading an air flow through the material layer in low pressure inwards from the surface, whereby the material which has absorbed the radiation distributes its heat to the air flow rinsing it, and the heat is transferred along with the air flow to the still damper portions of the material evaporating water therefrom according to the equilibrium between the relative humidity of air and the material humidity.

2. Bringing damp material corresponding the radiation evaporation effect by ruffling the lower layers to surface parts within the reach of the radiation. Under or, in some solutions, within the material to be dried has been placed an air distribution manifold (2), through which the drying air is led by a blower motor (1) to flow through the material to be dried selectively, either to a sucking direction with negative pressure or to a blowing direction with overpressure. Generally it is advantageous, mainly in sunny weathers, to use as a primary operational direction the one with negative pressure, because utilization of the radiation energy to deeper layers happens automatically in it, and to use as an auxiliary operational direction, mainly in unstable weathers and to equalize humidity differences between various material layers, the operational direction with S overpressure. When the covering means are in the covering position the amount of radiation coming to the material is negligible, and the amount of radiation in an unstable weather, especially when it is raining, is not very great.

The operational direction with overpressure can be utilized even systematically by materials, the repeated ruffling of which can relatively easily be arranged, or when reaching of the radiation deeper than the surface parts is not particularly strived on.

A necessary part considering the operation of the drier entity comprises an easily movable covering means (4) , functioning in a covering or spread position as a shelter from the rain and enabling in a removed or absorption position direct sun radiation to the material to be dried.

The two-part task of the covering means, sheltering from rain and enabling the sun radiation, succeeds well, because these tasks are performed in different times or they are alternatives for each other. If the drier structure is as shown in Fig. 2 and the covering means has been placed immediately above the material to be dried, only the operational direction with overpressure can be used when coverings are on. Air pressure lifts the covering to remove the blast air.

If the covering means is placed onto the actual rafters (11) as shown in Fig. 1, the operational direction with negative pressure is also possible when coverings are on. From the edges (8) sufficient air is supplied for air flow beneath the covering means. With materials sensitive for quality damages, as corn, when it is strived in the drying to utilize accurately the weathers, the transfer of the covering means to covering and absorption positions can be arranged to be easily performed by functions and equipment according to claims 12-15 and 19, whereby the covering means (4) is in the absorption position wound as a roll tube (12) and drawn in connection with the rotational movement of the roll tube (13) by bands or cords to give shelter from rain. It is advantageous to reduce friction during the movements of the covering to place an easily rotatable roll tube (14) at least at the ridge of the drier roof.

Operation of the electric motors functioning as the power source (10) for the covering means can be coupled as automatically controlled by a gauge metering the relative humidity in the air, whereby surpassing of the humidity threshold value couples the roll tube (13) motor to operation and a limit switch turns this operation off after the action. Underpassing of the humidity threshold value couples correspondingly the roll tube (13) to operation and after the action the limit switch turns this operation off. It is possible to use as the limit switch operation a method already known from other fields of technology, in which the identifying sensor (15) of the limit switch has been inserted to the edge of the covering means, and a sensor (16) in connection with the power supply (12/10 and 13/10) reacts with this sensor (15) and stops the operation. Automatic interlock for the rotational movement for both roll tubes (12 and 13) can be arranged for instance so, that a spring force (26) automatically locks (25) the rotational movement, and these interlocks are released by an electric magnet overcoming the spring force, which magnet creates the desired delay for the magnetizing current by activating in advance the electric motor for either roll tube.

Intermediate supporting of roll tubes (13 and 14) can easily be realized, because the covering means makes no hindrances for the supporting, but the supporting of the roll tube (12) allowing the rolling-to-tube of the covering means (4) is carried out by the solution shown in Fig. 7, in which the roll tube is placed into a wide recess, formed by several easily rotatable small rolls (23) along with the perimeter of the roll tube, to which rolls the roll tube is supported.

Beacuse of this structure the supporting is mainly directed downwards to the drier or depending on the existing loadings. Supporting does not receive upward loadings, but on the situations where they occur, or in a covering position when hard wind is blowing and the covering means has been released from the roll tube, a strong supporting can and should be used locking also the rotational movement of the roll tube, as for example a binding or other supporting.

Considering the covering function, when the covering is in a covering position and the blower operates, there should be a free escape path (8) for the air flow, but a shelter should exist even for slantingly falling rain.

Therefore the rafters (11) of the covering means and also the covering means (4) itself should extend as a sufficient long eaves outside the wall level (5). If grains are stored in the drier also for winter, the air flow openings (8) should also be protected against scurries of snow. This protection can easily be accomplished by arranging the rafter (11) as bending at its wall level in compliance with the claim 19 and Fig. 5. In the drying position the bent rafter can be lifted again up to the position shown in Fig. 5B, whereby an air flow opening (8) is again formed.

The joint has a turning radius pin (2) and a lock pin (21 and 22) for positions A and B. Because in the solution shown in Fig. 2 there is no ventilation air space (7) between the covering and the material to be dried, the covering means must be open at the ridge to remove sweating vapours.

In the solution according to Fig. 1, when a ventilation air space (7) is left between the covering and the material, the drier can be constructed with a uniform covering solution.

Because the material to be dried functions directly as a absorption surface, no radiation remains in the collection plate, but the efficiency is 100% up to the material to be dried. Also no collection structure is needed, but the collection takes place without costs. Without the collection structure there is neither any frictional resistance for the drying air caused by the collection device. )

The explanation concerning the above mentioned collection of sun radiation energy is valid also for the drier according to the invention, but additionally it can be stated that the coverless arrangement and the alternative operational direction with negative pressure of the drier is beneficial besides as a sun radiation collector and thus also as a significantly more efficient drier, also in the respect, that for example dust in the corn material, which would in the operational direction with overpressure be collected at the corn surface, is sucked under the negative pressure away with the air flow. The corn has therefore essentially less dust. In the conventional cool air drier with overpressure some crust is formed to the surface of the corn layer especially in the initial stage of the drying, which crust must continuously be broken. The origin of this crust formation is the dust material collected to the surface of the corn layer with the air flow and condensation of the moisture onto the surface layers. When the air saturated by water vapour is discharged to the cooler inner air of the drier building, the air reaches the dew point and the water vapour is condensed as water droplets and forms a dense crust together with the dust material risen to the material surface. In the operational direction with negative pressure the dust is sucked away from the material with the air flow, and when the air is discharged from the material to a relatively small air space in the air manifold, where the motion velocity is rather high compared with the air space in the drier and where the air temperature corresponds the material temperature, the dew point is not reached and the crust is therefore not formed. Though actual crust is in this case not formed, it is, however, possible to use for equalization of the moisture between different material layers the operational direction with overpressure as the auxiliary operational direction, if some factors require this. The equalization need for moisture can in some situations, mostly in the buffer driers having a strong corn layer, be so great that a systematic corn circulation is arranged from one part of the drier to another or from one drier to another. It should be noted, that drying takes place in the direction of the air flow and that also moisture progresses in the direction of the air flow.

With the drier according to the invention moisture differences can be equlaized by appropriate varying of the operational direction. However, if desired, the drier can be provided with a ruffling device (31) operated by a power engine (32) according to claims 20-23 and Figs. 8, 9 and 10. The ruffling device gets the transmission for rotation and movements by methods already known as such in other fields of the technology. Illustrations in Figs. 8, 9 and 10 are only some possible embodiments.

Propagation force is taken from the power engine (32) through a gear drive (34) or a friction transmission (35) of a V-belt via a gear wheel (33) and a transmission member (36), and the rotational force for the ruffling device (31) through a shaft (39) and a gearing, such as a planet gearing system (50). Location of the sheaves (37) and the power engine can be adjusted by elongated holes (41 and 42). Attachment of the transmission member (36) to the wall structure can be made laterally and verti- cally flexible with the solution according to Fig. 9 (45- 49) allowing thus "floating" operation. When parts 45 -49 are considered as seen from above, the space for movements in the vertical direction equals to the component height. A fastening plate (49) can be used for the attachment to the wall (5) to avoid wall damages. To the other end of the ruffling device and, with long ruffling devices, also in between should be placed the transmission gearings according to Fig. 8, though without the power engine (32, 34 and 35). The coverless drier has also a great meaning concerning the work technics.

The drier can easily be filled directly by the discharge horn of the harvester-thresher. The drier can be directly emptied for instance by a corn screw. A remarkable advantage is also the cost saving. Drying progresses always to the drying air movement direction and when the operational direction with negative pressure is used, the drying progresses from above downwards, whereby already dried material can selectively be removed from the surface of the drier also during the drying and thus facilitate the operation of blowers in the thinned corn layer.

The form of the air distribution channel in the drier, according to Fig. 1 or Fig. 2, is not critical for the the radiation collection device according to the invention.

The form of the drier, whether it is desklike or comprises high eller low ridge or is half-elliptic, is neither essential. It is essential, that the sun rays can freely fall to the material and that the radiation can be utilized for more effective drying than in surface parts, either by negative pressure or by ruffling the material layer.

For the drying device and method according to the invention the drier model and also the form of the air distribution channel as well as the location of the covering means have their own optimal suitability meaning in connection with different materials. Also the place of location can set forth its own suitability requirements. Materials which endure damages can for example have the solution shown in Fig. 2, and the materials sensitive to quality damages, as corn, can have the solution^■according to Fig. 1. Also the work-technical requirements of various materials and different circumstances determine, whether the walls (5) are allowed or not.

It is not wanted to tightly restrict the embodiments of the invention as those illustrated in the description and the figures, but these embodiments can rather widely be modified in compliance with the accompanying claims.

Brief description of the drawings

Figure 1 shows a cross-sectional view of a drier suitable for materials sensitive to quality damages, as corn, in which view a ventilation air space (7) is left between the covering means and the material to be dried in the covering position, and the air distribution channel (2) is totally under the material and the material is at a distance from the ground level, Figure 2 shows an embodiment which satisfies also the most severe requirements set forth in the drier filling and discharge technics, in which embodiment the air distribution channel (2) is partly placed into the material and the covering means (4) is directly above the material (3) in the covering position,

Figure 3 shows a schematic view of the Fig. 1, Figure 4 shows the bottom structure of the drier, Figure 5 shows a jointable eaves of the covering means rafter (11), Figure 6 shows the structure of the roll tube (14),

Figure 7 shows the intermediate supporting solution for the roll tube (12),

Figures 8 and 9 show the structure of the ruffling device, Figure 10 shows the location of the ruffling device in the drier,

Figure 11 shows a frictional locking embodiment of roll tubes (12 and 13), Figure 12 shows the location of the identification devices of the limit switch and the connection of the bands (18), needed for the installation to the covering position, to the covering means and the roll tube (13).

Claims

1. Method to collect sun radiation energy by driers, characterized in that the material (3) to be dried serves as the absorbing surface and that sun radiation energy is utilized for deeper drying than in surface parts by leading an air flow through the material in a sucking direction with negative pressure through an air manifold (2) under the material by a blower motor (1), and that the drier has been constructed without any fixed roof (4) and/or wall (5) structure to enable direct sun radiation (6) to the material.

2. Method according to claim 1, characterized in that the air flow is led in a blowing direction with overpressure through the material (3) to be dried and that sun radiation energy is utilized for deeper drying than in surface parts by ruffling the material layer.

3. Method according to claims 1 and 2, characterized in that the air flow is led through the material (3) to be dried via the air manifold (2), figure 2, inside the material by the blower motor (1).

4. Device for collection of sun radiation energy by driers, characterized in that the drier has no fixed roof (4) and/or wall (5) structure to enable sun radiation (6) directly to the material (3) to be dried and that the drying material (3) serves as the absorbing surface, and that sun radiation energy (6) is utilized for deeper drying than in surface parts by leading an air flow to a sucking direction with negative pressure through the material (3) to be dried through the air manifold (2), figure 1, under the material by the blower motor (1).

5. Device according to claim 4, characterized in that the air flow is led through the material to be dried via the air manifold (2), figure 2, inside the material (3) by the blower motor (1) .

6. Method according to claims 4 and 5, characterized in that the air flow is led in the blowing direction with overpressure through the material (3) to be dried and that sun radiation energy is utilized for deeper drying than in surface parts by ruffling the material layer.

7. Device according to claims 4-6, characterized in that the covering means (4) is directly above the material (3) to be dried when in covering position and that it is moved to covering and absorbing positions with supportings to the material.

8. Device according to claims 4, 6-7, characterized in that the covering means (4) is above covering means rafters (11) when in the covering position and that the covering means is moved to covering and absorbing positions with supportings to the rafters, and that in the covering position a ventilation air space (7) is left between the covering means (4) and the material (3) to be dried and that to enable an air flow an air gap (8) is left between the covering means (4) and the side wall (5).

9. Method for drying of different materials, characterized in that the drier has been constructed outdoors without any fixed roof (4) and/or wall structure (5) and that the air flow is selectively led through the material (3) to be dried by the blower motor (1) via the air manifold (2) , either in a sucking direction with negative pressure or in a blowing direction with over¬ pressure, and that in said method the material (3) to be dried is directly used as the collection surface for sun radiation energy and that sun radiation energy is utilized to a deeper drying than in the surface parts either with negative pressure by suction principle or by ruffling the material layer, and that in said method a tarpaulin or another easily transferable covering means (4) is used as protection from the rain.

10. Method according to claim 9, characterized^• in that the covering means (4) is placed above covering means rafters (11) when in the covering position and that the covering means is moved with supportings to the rafters, and that in the covering position a ventilation air space (7) is left between the covering means (4) and the material (3) to be dried and that to enable an air flow an air gap (8) is left between the covering means (4) and the side wall (5).

11. Device for drying of different materials, characterized in that the drier has been constructed outdoors without any fixed roof (4) and/or wall structure (5) and that the air flow is selectively led through the material (3) to be dried by the blower motor (1) via the air manifold (2), either in a sucking direction with negative pressure or in a blowing direction with over¬ pressure, and that the material (3) to be dried is directly used as the collection surface for sun radiation energy (6) and that sun radiation energy (6) is utilized to a deeper drying than in the surface parts either with negative pressure by suction principle or by ruffling the material layer, and that a tarpaulin or another easily transferable covering means (4) is used as protection from the rain.

12. Device according to claim 11, characterized in that at least one roll tube (12) is employed to move the covering means (4), onto which roll tube (12) the covering is rolled, when the sun radiation is collected, and the roll is opened having the covering means in its place.

13. Device according to claims 11 and 12, characterized in that, when the covering means (4) is placed to the rain-sheltering position or the covering roll is opened, the roll tube at the opposite edge of the drier in regard to the covering roll is used so, that the covering means is drawn over the drier upon rotating the tube by bands, cords etc. fastened to the roll tube (13).

14. Device according to claims 11-13 characterized in that the power source (10) for the turning mechanism of the roll tubes (12 and 13) comprises an electric motor and that the turning mechanism include a locking means (25-27) to interlock the rotational movement.

15. Device according to claim 14, characterized in that the operational control of the power source (12/10 and 13/10) has been arraganged to function automatically under guidance of an air moisture gauge, so that when a threshold value of the moisture gauge is surpassed, the power source (13/10) is turned on and a limit switch with identification connections breaks off the operation after the action is ended, and a correspondingly selected underpassing of a threshold value of the moisture gauge turns the power source (12/10) on and a limit switch with identification connections breaks off the operation after the action is ended.

16. Device according to claims 11-15, characterized in that to facilitate the frictional movement of the covering means (4) at least one set of easily rotatable roll tubes (14) has been placed transversally to the moving direction, over which tubes (14) the covering means (4) and/or bands lightly move.

17. Device according to claims 11-16, characterized in that the air manifold (2) is bounded downwards by the earth and at the ends by air-tight walls (5) and upwards by a perforated sheet metal under the material to be dried or similar air permeable bottom material (9 ) .

18. Device according to claims 11-17, characterized in that to achieve an air flow at least one blower motor ( 1 ) is employed having a reverse coupling for rotation needed to change the operational direction.

19. Device according to claims 11-18, characterized in that above the material (3) to be dried have slantingly been positioned covering means rafters (11), onto which the covering means (4) is placed in the rain sheltering position and on which the covering means is moved to covering and absorbing positions.

20. Device according to claims 11-19, characterized in that the covering means rafters (11) are jointed (19, 20) at their wall level and that the eaves portion of the rafter in the bending position (A) therefore closes off tightly for example scurries of snow, and that the eaves portion in straight (B) position forms an eaves which gives shelter also for slantingly falling rain allowing, however, the air flow required in the drying situation through the gap (8) left between the covering means (4) and the side wall (5), and that the joint mechanism has locking points (21 and 22) for both positions A and B.

21. Device according to claims 11-20, character!zed in that at least one ruffling device with a power engine is employed for ruffling the material.

22. Ruffling device for material according to claim 21, characterized in that the ruffling device comprises a drumlike elongated cylinder (31) having on its surface projections (40), the form of which is suitable for the operational situations, which cylinder ruffles the material (3) when rotating about its longitudinal axle, and that said cylinder is in transmission connection with at least two transmission members (36) rectangular in regard to the cylinder, whereby the ruffling device progresses supported to these members on the material surface to its rotational direction.

23. Device according to claim 22, characterized in that between the rotational speed and the progression speed and the progression direction of the ruffling device there is a transmission gearing (50) changing their mutual relationships, whereby the ruffling device can be employed as a sweeping device also to transfer the material.

24. Device according to claims 11-21, characterized in that the transmission member (36) has been fastened to the wall structure (5 and 49) by a mechanism (45, 46 and 47) allowing movements in lateral and vertical directions.