WO2013182744A2 - Dryer and method for drying material - Google Patents

Dryer and method for drying material Download PDF

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Publication number
WO2013182744A2
WO2013182744A2 PCT/FI2013/050589 FI2013050589W WO2013182744A2 WO 2013182744 A2 WO2013182744 A2 WO 2013182744A2 FI 2013050589 W FI2013050589 W FI 2013050589W WO 2013182744 A2 WO2013182744 A2 WO 2013182744A2
Authority
WO
WIPO (PCT)
Prior art keywords
drying gas
space
dryer
conveying
dried
Prior art date
Application number
PCT/FI2013/050589
Other languages
French (fr)
Other versions
WO2013182744A3 (en
Inventor
Pekka AHVENSALMI
Heikki Majava
Markku SORVARI
Original Assignee
Ccm-Power Oy
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Ccm-Power Oy filed Critical Ccm-Power Oy
Priority to EP13799978.5A priority Critical patent/EP2859292A4/en
Publication of WO2013182744A2 publication Critical patent/WO2013182744A2/en
Publication of WO2013182744A3 publication Critical patent/WO2013182744A3/en

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Classifications

    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F26—DRYING
    • F26B—DRYING SOLID MATERIALS OR OBJECTS BY REMOVING LIQUID THEREFROM
    • F26B17/00—Machines or apparatus for drying materials in loose, plastic, or fluidised form, e.g. granules, staple fibres, with progressive movement
    • F26B17/18—Machines or apparatus for drying materials in loose, plastic, or fluidised form, e.g. granules, staple fibres, with progressive movement with movement performed by rotating helical blades or other rotary conveyors which may be heated moving materials in stationary chambers, e.g. troughs
    • F26B17/20—Machines or apparatus for drying materials in loose, plastic, or fluidised form, e.g. granules, staple fibres, with progressive movement with movement performed by rotating helical blades or other rotary conveyors which may be heated moving materials in stationary chambers, e.g. troughs the axis of rotation being horizontal or slightly inclined
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F26—DRYING
    • F26B—DRYING SOLID MATERIALS OR OBJECTS BY REMOVING LIQUID THEREFROM
    • F26B21/00—Arrangements or duct systems, e.g. in combination with pallet boxes, for supplying and controlling air or gases for drying solid materials or objects
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F26—DRYING
    • F26B—DRYING SOLID MATERIALS OR OBJECTS BY REMOVING LIQUID THEREFROM
    • F26B3/00—Drying solid materials or objects by processes involving the application of heat
    • F26B3/02—Drying solid materials or objects by processes involving the application of heat by convection, i.e. heat being conveyed from a heat source to the materials or objects to be dried by a gas or vapour, e.g. air
    • F26B3/06—Drying solid materials or objects by processes involving the application of heat by convection, i.e. heat being conveyed from a heat source to the materials or objects to be dried by a gas or vapour, e.g. air the gas or vapour flowing through the materials or objects to be dried

Definitions

  • the invention relates to a dryer for drying material, the dryer comprising the first end and the second end, and the material to be dried is arranged to be fed into the dryer from the first end and to be discharged from the second end, and the dryer comprises a conveying space for the conveying arrangement of the material to be dried, and a drying gas space, and when the dryer is in its drying position, the drying gas space is above the conveying space, a cover construction, which is arranged to separate the drying gas space and the conveying space, and the cover construction comprises apertures between the drying gas space and the conveying space, and the drying gas space is divided into compartments, and the drying gas is arranged to flow at least between some compartments of the drying gas space through the conveying space. Furthermore, the invention relates to a method for drying material, in which method a dryer is used, comprising the first end and the second end.
  • dryers using warmed drying gas are known which dryers are filled with material to be dried, and after the material has achieved the desired dryness the reservoir is emptied.
  • dryers are known, in which the material to be dried is contained in cages that are movable in the dryer in relation to the current of air, and the cage, where the material is dried, is removed from the dryer, and a cage with material to be dried is added thereto.
  • These dryers are slow to operate and require a lot of measures and controlling.
  • the drying pro- cess has to be stopped for the time of emptying and filling.
  • the drying air is discharged from the upper portion of the dryer and taken in to the dryer at its lower portion, in the example of the publication, next to the feeding point.
  • the drying effect of the current of air is intensified by building a guide that guides the current of air to flow better, thereby drying the material.
  • it is aimed at providing a system, where a better drying effect would be provided with the same amount of air and speed thereof, whereby it is avoided that the material to be dried starts to move along with the current of air.
  • a part of the heat of the drying air is wasted when it comes out of the dryer.
  • the object of the invention is a solution, by which the disadvantages and drawbacks of the prior art can be diminished.
  • the object of the invention is a solution, by means of which a dryer is provided, which is lightweight and quick to use.
  • the objects according to the invention are achieved by a dryer, characterized in what is disclosed in the independent claim. Some preferred embodiments of the invention are disclosed in the dependent claims.
  • the main idea of the invention is to form a dryer with a drying gas space and beneath it a conveying space, where the material to be dried is conveyed.
  • the dry- ing gas space is divided into compartments.
  • the drying gas is directed through the dryer in such a way, that it flows from one compartment into another at least along one path. At least between some compartments the drying gas flows via the conveying space and at the same time through the material to be dried that is conveyed therein.
  • upper or lower side or similar. directions in the text a situation is described, where the dryer according to the invention is in its operating position.
  • the dryer for drying material comprises the first end and the second end, and the material to be dried is provided to be fed to the dryer from the first end and to be discharged from the second end.
  • the dryer comprises a conveying space for the conveying arrangement of the material to be dried, and when the dryer is in its drying position, the drying gas space is above the conveying space, and the drying gas space is divided into compart- ments, and the drying gas is provided to flow at least between some compartments through the conveying space.
  • the conveying space is formed in a way that at least in some points it comprises positions where the drying gas flows through the material to be dried, when the conveying arrangement is conveying the material, that is, when the dryer is in operation.
  • the conveying arrangement situated in the conveying space comprises at least a first screw conveyor and a second screw conveyor that are parallel, and between the said screw conveyors there is a longitudinal division wall, and in lower part of the division wall there is a formation that extends to the space between the screw conveyors and is provided to direct drying gas through the material to be dried.
  • At least one path is provided for the drying gas through the dryer, where it flows alternating through the drying gas space and the conveying space. There may be also several paths, and they may be joined together or branched out.
  • drying gas is provided to be fed to at least one compartment of the drying gas space and to be discharged from at least one compartment of the drying gas space, which is not the same one, to which drying gas has been fed.
  • the dryer compris- es at least one compartment of the drying gas space, from where drying gas is provided to be discharged from the conveying space, the compartments being provided in a way that the drying gas flows at least in a part of the conveying space upstream to the direction of motion of the material to be dried between said compartments.
  • the dryer comprises at least one compartment of the drying gas space, from where drying gas is provided to move to the conveying space, and at least one compartment of the drying gas space, to which drying gas is provided to be discharged from the conveying space, the compartments being provided in a way that the drying gas flows at least in a part of the conveying space downstream to the direction of motion of the material to be dried between said compartments.
  • the dryer comprises at least one compartment of the drying gas space, from where drying gas is provided to move to the conveying space, and at least one compartment of the drying gas space, to which drying gas is provided to be discharged from the conveying space, the compartments being provided in a way that the drying gas flows at least in a part of the conveying space transversely to the direction of motion of the material to be dried between said compartments.
  • At least a part of the compartments of the drying gas space is provided in a way, that transfer of the drying gas into the conveying space and exit of the drying gas from the drying space are provided in a way, that the drying gas flows in the conveying space in several different directions in relation to the direction of motion of the material to be dried.
  • drying gas can be fed to several compartments of the drying gas space, or the drying gas has several paths to the conveying space from the compartment, to which drying gas is fed, or as a combination of the aforementioned.
  • At least a part of the openings of the cover structure comprises a screen arrangement or similar to pre- vent the material to be dried from entering the drying gas space.
  • the drying gas is provided to flow at least between some compartments through openings in the cover structure, whereby the drying air exits from one compartment from an opening therein to the conveying space and enters from a conveying space to another compartment through an opening therein.
  • the screw system and the direction of rotation of the first screw conveyor and the second screw conveyor in the conveying arrangement in the conveying space are provided in a way that their outlet direction is between the screw conveyors.
  • said shaping between the first and second screw conveyors is essentially in form of the outer surfaces of the screw conveyors and is above the shafts of the screw conveyors, when the dryer is in its operational position.
  • the inner surface of the conveying space is at least partly in form of the outer surface of the screw conveyor or screw conveyors.
  • the first end of the dryer when the dryer is in drying position, the first end of the dryer is situated lower than the second end. Thereby, the dryer is inclined.
  • the water being condensed in the dryer is provided to run to the first end, which comprises a water discharge arrangement.
  • a dryer with the first end and the second end is used for drying bulk material.
  • the dryer used in the method comprises further a conveying space for the conveying arrangement of the material to be dried and a drying gas space, a cover structure, that is provided to separate the drying gas space and the conveying space, and the cover structure comprises openings between the drying gas space and the conveying space, and when the dryer is in its drying position, the drying gas space is above the conveying space, and the drying gas space is divided into compartments.
  • the conveying arrangement situated in the conveying space comprises at least a first screw conveyor and a second screw conveyor that are parallel, and between said screw conveyors there is a longitudinal separation wall, and in lower part of said separation wall there is a shaping that extends to the space between the screw conveyors and is provided to direct the drying gas through the material to be dried.
  • the method comprises steps, in which the material to be dried is fed at the first end of the dryer to the conveying space, where the conveying arrangement for conveying the materi- al to be dried is situated, the drying gas is fed to the drying gas space, the drying gas flows at least between some compartments through the conveying space travelling guided by the shaping in the lower part of said longitudinal separation wall through the material to be dried conveyed by the conveying arrangement, and the material to be dried is discharged out of the dryer at the second end of the dryer.
  • the first end of the dryer is lower than the second end, and the drying gas conveys the water vapour separated from the material which is dried at the upper part of the dryer to the lower part of the frame, where the water vapour is condensed onto the surface of the material to be dried and thereby releases heat to the material to be dried.
  • An advantage of the invention is that by it a dryer is provided that can, when necessary, be used continuously, quickly and cost-effectively. This enables, for example, industrial production of biofuel from material to be dried.
  • the invention further enables that in order to convey the drying gas through the dryer and at the same time through the material to be dried such a high pressure difference is not necessary than in dryers according to the prior art.
  • An advantage of the dryer is that by means of it a dryer, drying material in industrial scale and being movable can be provided.
  • An advantage of the invention is further that by means of it the whole drying or pre-drying of the material can be performed.
  • an advantage of the invention is that it is applicable to different types of materials to be dried.
  • An advantage of the invention is further, that it enables simple adjusting of the dryer when the humidity of the material to be dried varies.
  • Figure 1 shows by way of example an arrangement for drying material, with a dryer according to the invention
  • Figure 2 shows by way of example a perspective view of the dryer according to
  • Figure 3 shows by way of example the conveying space of the dryer according to Figure 1 ,
  • Figure 4 shows by way of example the dryer according to Figure 1 .
  • Figure 5 shows by way of example the movements of the drying gas between the drying gas space and conveying space of a dryer according to a second invention
  • Figure 6 shows by way of example the movements of the drying gas between the drying gas space and conveying space of a dryer according to a third invention
  • Figure 7 shows by way of example the movements of the drying gas between the drying gas space and conveying space of a dryer according to a fourth invention
  • Figure 8 shows by way of example the cross-section of the dryer according to a fifth invention and the movements of the drying gas
  • Figure 9 shows by way of example the movements of the drying gas between the drying gas space and conveying space of a dryer according to a sixth invention.
  • Figure 1 shows an example of the arrangement for drying material, with a dryer 100 according to the invention.
  • the arrangement comprises a store of the material to be dried 102, a conveying arrangement for the material to be dried 101 , a support arrangement 105, a heating device of the drying gas 103, and an additional dryer 104.
  • the material to be dried is kept in a reservoir 102 of the material to be dried.
  • the storage may be fixed, such as a silo, or movable, such as for example a pallet or a container.
  • the dryer and the peripheral devices related to it may be moved to the vicinity of the storage of the material to be dried, or the storage may be brought to the vicinity of the dryer.
  • the material to be dried may be organic, such as for example, chopped firewood or wood chips. It may also be gravel or sand.
  • the mate- rial to be dried may also be a mix of a suspension ⁇ and some bulk material.
  • the material to be dried is bulky.
  • the material to be dried is conveyed by the conveying arrangement 101 from the storage of the material to be dried 102 to the dryer 100.
  • the dryer is set into drying position by means of support arrangement 05.
  • the dryer is in an inclined position by means of a support arrangement, and the material to be dried is fed to the lower end. If the dryer is, for example, in horizontal position, the support arrangement is not necessarily required.
  • the position of the dryer can also be varied with the support arrangement.
  • the material to be dried is dried by means of drying gas.
  • the gas is preferably air, but it may also be some inert gas, such as nitrogen.
  • the gas is preferably heated.
  • the gas is heated by a heating device 103 of the drying gas. In some cases, the drying gas does not have to be heated, but the gas flow is sufficient. Some prior art is used for heating the gas.
  • the material to be dried that has passed through the dryer is discharged at the other end of the dryer than from which it was fed thereto.
  • the dryer 100 according to the invention functions as a pre-dryer, and the final drying is performed in an additional dryer 104.
  • the additional dryer may be, for example, a dryer where a vertical mattress is formed from the material to be dried, and through which drying gas is blown.
  • the additional dryer may also be of different kind.
  • One possible arrangement is to locate two or more dryers according to the invention one after another, which dry- ers have been adapted to dry materials with different humidities. Drying of the material to be dried can naturally be performed by using only the drying according to the invention. Thereby, an additional dryer is not necessary.
  • FIG. 2 shows an example of the dryer 100 according to the invention that is used in an arrangement according to Figure 1.
  • the dryer is shown in a perspec- tive view, where some of the side wall of the dryer is removed in order to increase clarity.
  • the dryer comprises a frame that protects and supports the dryer.
  • the dryer comprises the first end 208 and the second end 20 .
  • the dryer comprises a drying gas space 204 and a conveying space 202. When the dryer is in its drying position, the drying gas space is above the conveying space.
  • the drying position of the dryer is an inclined position, whereby the first end of the dryer is lower than the second end.
  • the drying position of the dryer may also be some other position. It may be in horizontal position or positioned such that its first end is higher than the second end.
  • the material to be dried travels in the dryer through the conveying space 202. Also the drying of the material to be dried is performed in the conveying space.
  • the material to be dried is fed to the dryer and the conveying space at the first end of the dryer.
  • above the frame of the dryer there is an opening 205, through which material to be dried can be dropped through the drying gas space 204 to the conveying space.
  • the conveying space comprises a conveying arrangement for conveying the material to be dried through the dryer from the first end to the second end.
  • the conveying arrangement can be realized, for example, by a conveyor belt, moving plates, screw conveyors or similar arrangements or combinations thereof, that are able 1o convey material to be dried and at the same time enable drying gas passing through the material to be dried at least in parts of the conveying space.
  • two screw conveyors are used: the first screw conveyor 210 and the second screw conveyor 211.
  • the screw conveyors are parallel and in direction of the conveying space and extend through the whole conveying space.
  • the conveying space and the screw conveyors are arranged such that no material to be dried remains in the conveying space. This has been able to be realized by shaping of the surfaces of the conveying space and positioning of the screw conveyors.
  • the screw system that is, the thread and direction of rotation of the screw conveyors is provided in a way that their outlet direction is between the screw conveyors, that is, material is transferred between the screw conveyors.
  • the threads of the screw conveyors are differently handed, they rotate in dif- ferent directions.
  • the screw conveyors are parallel, the material to be dried is transferred from one screw conveyor to another.
  • an opening or openings or space is provided between the screw conveyors.
  • At some points between the screw conveyors there may be support structures or walls that extend from the bottom of the conveying space to its ceiling.
  • the drying gas space 204 is divided into compartments 203.
  • Drying gas is fed to at least one compartment of the drying gas space, and it is discharged out of at least one compartment of the drying gas space, and these compartments are different compartments. These compartments are not connected to each other through the drying gas space. Pressure difference is provided between the feed- ing and discharge points of the drying gas, so that the drying gas aims at flowing from the feeding point to the discharge point.
  • the drying gas flows in the dryer 100 in a way that at least between some compartments of the drying gas spaces the drying gas flows through the conveying space 202, and when the dryer is in operation, at the same time through the material to be dried, conveyed by the conveying arrangement, drying it.
  • the drying gas flows through the dryer along a path, where it is in the drying gas space and in the conveying space, alternatively.
  • the drying gas space is essentially tight, such that the drying gas can escape the drying gas space only at predetermined points.
  • Some compartments of the drying gas space may be connected to each other without the drying gas entering the conveying space. These compartments do not need to be adjacent.
  • the compartments are separated by walls that may comprise openings or other arrangements, such as pipes or passages, for directing the drying gas from one compartment to another.
  • the compartments may comprise a floor that may comprise one or several holes, or the bottom of the compartment may be open, thus forming an opening of the size of the compartment from the drying gas space to the conveying space.
  • the drying gas is fed to a compartment situated in the vicinity of the second end 201 of the dryer, and it is discharged from the dryer from the compartment 207 situated in the vicinity of the first end 208 through opening 206.
  • the opening may comprise an auxiliary pump for improving the pressure difference between the ends of the dryer, or it may comprise a filter for removing dust or similar.
  • drying gas flows into the compartment 209, through which material to be dried is fed to the dryer.
  • the gas may flow, for example, either from a previous compartment of the drying gas space or from the conveying space 202 from the wall of compartment 209 or through an opening in the floor (not shown).
  • a cover structure may exist between the drying gas space 204 and the conveying space to separate said spaces.
  • the cover structure comprises openings, through which the drying gas flows from a compartment of the drying gas space into the conveying space, or vice versa.
  • the cover structure of the dryer may also be realized in a way that the bottom of some compartments of the drying gas space is open and the one of some compartments it is closed, or the bottom of all com- partments is open.
  • the cover structure forms the bottom of the drying gas space and the roof of the conveying space.
  • Figure 3 shows an example of a part of the conveying space 202 of the dryer according to Figure 1.
  • the conveying space comprises the first screw conveyor 210 and the second screw conveyor 211.
  • the conveying space comprises surface 301.
  • the surface may be a part of the frame, or it may be at least partly separated from it.
  • the surface is formed to fol- low the shape of the outer edge, that is the screw thread, of the screw conveyors. Thus, remaining of regions in the conveying space where material to be dried would accumulate is avoided.
  • the surface of the conveying space between the screw conveyors is essentially flat.
  • this space may comprise a movable arrangement that removes the clogs and moves material to be dried to be conveyed by the screw conveyors.
  • This movable arrangement may, for example, be a plough-like plate structure or similar, moving on a rail.
  • the portion of the conveying space 202 comprises two open- ings between the conveying space and the drying gas space: the first opening 304 and the second opening 303.
  • the conveying space further comprises structures for directing the passage of the gas in the conveying space.
  • these include a first transversal separation wall 305, a second transversal separation wall 307 and a longitudinal separation wall 306.
  • the first opening is at the position of the first screw conveyor, and the second opening is at the position of the second screw conveyor.
  • the openings are in connection with two different compartments of the drying gas space that are not connected to each other via the drying gas space.
  • the upper portion of the opening is essentially of the size of a compartment of the drying gas space, and the lower portion of the opening is smaller than the upper portion of the opening.
  • the openings may comprise screens or similar to prevent the material to be dried from getting into the drying gas space.
  • the first opening is limited by the surface 301 of the conveying space, the first transversal separation wall 305 and the longitudinal separation wall 306.
  • the second opening is limited by the surface 301 of the conveying space, the second transversal separation wall 307 and the longitudinal separation wall 306.
  • the longitudinal separation wall is parallel to the direction of the screw conveyors and essentially in the region between the screw conveyors. In the case according to the example, it widens out towards the screw conveyors, that is, it narrows the width of the lower portion of the openings.
  • a shaping 302 that extends to the space between the screw conveyors.
  • the shaping is essentially in the form of the outer surface of the screw conveyors.
  • the shaping is for directing the movements of the drying gas in the conveying space.
  • the shaping guides the drying gas in a way that it does not flow between the screw conveyors through a void space possibly formed above their shaft level, but is directed onto such a path that it passes through the material to be dried, when it exists in the conveying space.
  • an opening or space through which the mate- rial to be dried is transferred from one screw conveyor to another.
  • the transversal walls exist to prevent the drying gas from flowing in longitudinal direction above the material to be dried.
  • first and the second transversal wall do not need to be at corresponding points at the positions of the first and the second screw conveyor. Further, transversal walls do not need to exist in the same number at different screw conveyors.
  • the transversal walls and the longitudinal separation wall form compartments in the conveying space.
  • the drying gas is provided to flow between these compartments of the conveying space in a way that it passes through the material con- veyed by the screw conveyors. This may be provided such that the gas flows between the compartments of the conveying space in direction of the screw conveyor, that is, it flows under the transversal wall or flows transversely to the screw conveyors, whereby it flows under the longitudinal separation wall.
  • Directing of the drying gas is realized by positioning of the openings of the cover structure.
  • the gas-directing structures of the conveying space can be realized in several different ways. These can be realized, for example, by using a longitudinal separation wall and its openings or transversal walls or a combination of both.
  • FIG 4 shows an example of the dryer according to Figure 1.
  • the figure shows the positioning of the conveying space 202 and the drying gas space 204 of the dryer in relation to each other, and an example of the path of the drying gas in the dryer.
  • Direction of the movement of the material to be dried in the dryer is indicated with an arrow 403.
  • the drying gas space comprises compartments that are separated from each other by walls. In this example, the walls are situated at the walls of the conveying space shown in Figure 3 such that they form extensions to each other.
  • the first compartment 401 and the second compartment 402 are indicated.
  • movements of the drying gas are indicated by a broken line. From the first compartment the drying gas flows to the conveying space. This is indicated by a broken line arrow pointing downwards.
  • the drying gas flows to direction of lower pressure in the conveying space. This can be guid- ed by positioning the walls of the conveying space and the openings of the drying gas space in order to provide the desired gas flow.
  • the gas flow is arranged according to the desired properties of the dryer. In the example, this direction of lower pressure is in the direction of the opening situated at the second compartment in the conveying space.
  • this direction of lower pressure is in the direction of the opening situated at the second compartment in the conveying space.
  • the drying gas flows in the stream of the ma- terial to be dried transversely to its movement.
  • the drying gas moves to the second compartment of the drying gas space from the conveying space through the opening at the second compartment. Movement of the drying gas is indicated by a broken line arrow pointing upwards.
  • FIG. 5 shows an example of the movements of the drying gas between the drying gas space and conveying space of a dryer according to the second invention.
  • the dryer is shown from above, and the direction of the material to be dried in the dryer is indicated by a thick line.
  • the drying gas space is divided into compartments, and the drying gas flows between the compartments either directly, from one compartment to another or through the conveying space.
  • the continuous line arrows represent the movement of the drying gas between the compartments of the drying gas space
  • the broken line arrows represent the movement of the drying gas in the conveying space between the compartments of the drying gas space.
  • the drying gas is fed to the compartment 501 of the drying gas space, and it is discharged from the dryer from the compartment 504 of the drying gas space.
  • an opening 502 to the conveying space.
  • the gas flows through compartment 503.
  • the flow of gas in the drying space is guided by transversal separation walls, a longitudinal separation wall and its possible openings, or both.
  • compartments and openings are provided such that in the portion of the dryer that is closer to the end, from where the material to be dried is discharged from the dryer, the drying gas flows in the conveying space against the flow direction of the material to be dried. In the portion of the dryer that is closer to the end, where the material to be dried is fed to the dryer, the drying gas flows in the conveying space essentially transversely to the flow direction of the material to be dried.
  • the drying gas can have movements in two different directions in the conveying space. Naturally, several different paths and path combinations can be provided for the drying gas.
  • Figure 6 shows an example of the movements of the drying gas between the drying gas space and conveying space of a dryer according to the third invention. Markings and viewing direction are the same as those in Figure 5.
  • the drying gas is fed to the compartment 601 of the drying gas space, and it is discharged from the dryer from the compartment 603 of the drying gas space.
  • the compartments of the drying gas space are positioned one after another, and the drying gas flows in the conveying space in opposite direction to the movement of the material to be dried.
  • Figure 7 shows an example of the movements of the drying gas between the dry- ing gas space 706 and conveying space 707 of a dryer according to the fourth invention.
  • the dryer is viewed from the side.
  • the dryer comprises the first end 711 and the second end 710. Movement of the material to be dried through the dryer in the conveying space is indicated by arrow 709. Movements of the drying gas are indicated by broken line arrows 713.
  • the dryer In its operation, the dryer is in hori- zontal plane.
  • the compartments of the drying gas space 706 are on two levels.
  • the upper level 714 is in the upper portion of the dryer, and the lower level 715 is between the upper level of the drying gas space and the conveying space.
  • a feeding compartment 701 On the upper level of the drying gas space there is a feeding compartment 701 , a delivery compartment 702 and a discharge compartment 705.
  • a delivery compartment 702 On the lower level of the drying gas space there is the first compartment 712, the second compartment 703, the third compartment 704, the fourth compartment 716 and the fifth compartment 717.
  • a cover structure 708 Between the drying gas space and the conveying space 707 there is a cover structure 708, which comprises openings at the position of the compartments of the lower level.
  • the drying gas is fed to the feeding compartment 701. From the same source of drying gas, drying gas can be fed to the delivery compartment 702. In the bottom of the feeding compartment there is an opening, from where the drying gas can get into the first compartment 712 of the lower level. From there the drying gas gets from an opening in the cover structure 708 into the conveying space 706. The drying gas flows against the direction 709 of the material to be dried and leaves the conveying space to the second compartment 703 from an opening in the cover structure.
  • the cover structure In the cover structure, at the second compartment, there is a second opening, from which the gas gets into the conveying space, through which it gets to flow into the third compartment 704, at which the cover structure, in the same way, comprises two openings, through which the drying gas flows correspondingly to how it does flow from the openings at the second compartment.
  • the fourth compartment 717 is similar to the second compartment, except that it comprises an arrangement, for example an opening, by means of which more drying air is brought to the fourth compartment through delivery compartment 702. From the fourth compartment the drying gas flows through the conveying space into the fifth compartment 713, at which the cover structure comprises one open- ing. From the fifth compartment the drying gas moves to the discharge compartment 705, from where the drying gas is discharged from the dryer.
  • the drying gas By means of a two-level drying gas space the drying gas can be guided to desired spots in the dryer and the path of the drying gas can be adjusted.
  • the two-level model can be realized in several other ways than the one described in the example.
  • FIG 8 shows an example of the conveying space of a dryer according to the fifth invention in a cross-section and movements of the drying gas at the point in question.
  • the movements of the drying gas are indicated by broken line arrows.
  • the conveying space comprises the first 802 and the second screw conveyor 806, that are parallel and in direction of the conveying space.
  • the surface 801 of the conveying space is essentially in the form of the outer surface of the screw conveyors.
  • the surfaces of said shapings are essentially in the form of the outer surfaces of the screw conveyor such that there remain as few void spaces as possible, when material to be dried is conveyed through the dryer.
  • An opening 805 remains between the shapings, through which opening the drying gas can flow.
  • the opening between the shapings may be above or below the level between the axes of the screw conveyors, that is one or the other of the shapings extends over said level.
  • the screw conveyors rotate in a way that the material to be dried, conveyed by them, tries to get through the opening from both screw conveyors to the other screw conveyor.
  • the material to be dried remains in motion and is not allowed to clog on one or the other screw conveyor.
  • drying gas gets from the drying gas space to the conveying space through the opening situated above the second screw conveyor.
  • the drying gas flows through the material to be dried, conveyed by the thread of the screw conveyor and passes through the opening 805 to the first screw conveyor. There, the drying gas passes through the material to be dried, conveyed by the thread through the opening above the first screw conveyor back to the drying gas space, but to a different compartment than from where it came. Flow of the drying gas is directed towards smaller pressure. Path of the drying gas can be guided, that is, pressure differences can be adjusted by means of the structures of the conveying space, of which examples are given in connection with Figure 3.
  • Figure 9 shows an example of the movements of the drying gas between the drying gas space and conveying space of a dryer according to the sixth invention.
  • Movements of the drying gas in the drying gas space are indicated by an arrow with a continuous line, and in the conveying space by an arrow with a broken line.
  • the feeding compartment 905 of the drying gas is in the middle portion of the dryer, and there are two discharge compartments: the first dis- charge compartment 901 and the second discharge compartment 906, that are at the ends of the dryer.
  • the compartments of the drying gas space comprise openings 904, through which the drying gas flows to the conveying space, and openings 902, through which the drying gas flows from the conveying space into the drying gas space. From the feeding compartment 905 the drying gas flows in the drying gas space to two other compartments and through the conveying space to one compartment.
  • drying gas proceeds to the next compartment in a way that the drying gas flows in the conveying space essentially transversely to the movement of the material to be dried.
  • the paths of the drying gas according to the example in the drying gas space may be realized, for exam- pie, by means of a two-level drying gas space, described in Figure 7.

Abstract

The dryer (100) for drying material according to the invention comprises the first end (208) and the second end (201 ), and the material to be dried is provided to be fed to the dryer from the first end and to be discharged from the second end. The dryer comprises a conveying space (202) for the conveying arrangement (210, 211 ) of the material to be dried, and a drying gas space (204). When the dryer is in its drying position, the drying gas space is above the conveying space, and the drying gas space is divided into compartments (203, 207, 209), and the drying gas is provided to flow at least between some compartments through the conveying space. The conveying space is formed in a way that at least in some points it comprises positions where the drying gas flows through the material to be dried, when the conveying arrangement is conveying the material to be dried, that is, when the dryer is in operation. At least one path is provided for the drying gas through the dryer, where it flows alternating through the drying gas space and the conveying space. There may be also several paths, and they may be joined together or branched out. The dryer can be used for drying bulk material.

Description

Dryer and method for drying material
The invention relates to a dryer for drying material, the dryer comprising the first end and the second end, and the material to be dried is arranged to be fed into the dryer from the first end and to be discharged from the second end, and the dryer comprises a conveying space for the conveying arrangement of the material to be dried, and a drying gas space, and when the dryer is in its drying position, the drying gas space is above the conveying space, a cover construction, which is arranged to separate the drying gas space and the conveying space, and the cover construction comprises apertures between the drying gas space and the conveying space, and the drying gas space is divided into compartments, and the drying gas is arranged to flow at least between some compartments of the drying gas space through the conveying space. Furthermore, the invention relates to a method for drying material, in which method a dryer is used, comprising the first end and the second end.
PRIOR ART
In usage of material to be burned one of the most significant factors affecting quality is the dryness of the material. A traditional way of reducing humidity of timber, such as firewood billets or chopped firewood, is to dry it in stacks or piles for one to two years. Drying may take place indoors or outdoors. Problems are caused by variation of quality, becoming mouldy, possible insect infestation, appearance drawbacks and seasonal nature of production. Also slow circulation of stock and large spaces required by the drying performed on a larger scale create obstacles for commercial use. For speeding up and intensifying the drying dryers have been produced that use current of air and/or warming.
In cold air drying outdoor air is blown through the material to be dried. An advantage of the method is that it is quite inexpensive and requires simple structures. It is too slow for actual industrial drying and too dependent on the tempera- ture and humidity of the outdoor air to be used. Also sizes of the dryer and the storage facilities become impractically large.
When warming the drying gas and when blowing it through the material to be dried the drying is performed quicker than by using unwarmed gas. The quality of the dried material is improved and the final humidities are lower. The dryers, however, become more complicated and expensive than the cold-air dryer.
Reservoir-like dryers using warmed drying gas are known which dryers are filled with material to be dried, and after the material has achieved the desired dryness the reservoir is emptied. Also dryers are known, in which the material to be dried is contained in cages that are movable in the dryer in relation to the current of air, and the cage, where the material is dried, is removed from the dryer, and a cage with material to be dried is added thereto. These dryers, however, are slow to operate and require a lot of measures and controlling. Furthermore, the drying pro- cess has to be stopped for the time of emptying and filling.
In patent publication US3391472, an apparatus for cooling and drying pellets, where the pellets are fed from below vertically into the dryer, which comprises box-like means for lifting the pellets upwards inside the dryer. In the upper section of the dryer there is a fan that sucks air through the dryer, whereby air flows in the same direction with the pellets. Air gets into the dryer at the lower portion of the dryer. At the upper portion of the dryer, the pellets are emptied and removed from the dryer. From patent publication US3432940 an apparatus to be used for drying sand and similar material is known. It comprises a substantially vertical dryer, where the material to be dried is transferred in vessels attached to the conveyor belt from below upwards. The drying air is discharged from the upper portion of the dryer and taken in to the dryer at its lower portion, in the example of the publication, next to the feeding point. The drying effect of the current of air is intensified by building a guide that guides the current of air to flow better, thereby drying the material. Here, it is aimed at providing a system, where a better drying effect would be provided with the same amount of air and speed thereof, whereby it is avoided that the material to be dried starts to move along with the current of air. In these solutions, a part of the heat of the drying air is wasted when it comes out of the dryer. In the same way, in described solutions there is a lot of unused space, for which air has to be warmed, and in addition, they enlarge the size of the appa- ratus.
In patent publication US6370797, a dryer operating in counterflow principle. Therein the aim is to dry granular material, as an example plastic pellets are used. The pellets fall vertically in the dryer by means of gravity from above downwards, and the drying gas is directed against the direction of motion. Also in patent publi- cation WO2007/061352, a counterflow type dryer is disclosed. This has been designed, for example, for drying of sawdust or corresponding fine-grained material. Here, the material to be dried is conveyed from above downwards on a spiral conveyor, and the drying air is directed from below upwards. These arrangements contain waste space and applying them to drying different materials is difficult.
From patent publication US4823479, a dryer is known that consists of several modular units with different drying conditions. The material to be dried is transferred on the conveyor belt through the dryer, and the drying capacity of the dryer is optimized in different parts of the dryer according to humidity of the material to be dried. The dryer according to the publication gets quite large, and the material to be dried has to be spread into a very thin layer on the conveyor belt. SUMMARY
The object of the invention is a solution, by which the disadvantages and drawbacks of the prior art can be diminished. Particularly, the object of the invention is a solution, by means of which a dryer is provided, which is lightweight and quick to use. The objects according to the invention are achieved by a dryer, characterized in what is disclosed in the independent claim. Some preferred embodiments of the invention are disclosed in the dependent claims.
The main idea of the invention is to form a dryer with a drying gas space and beneath it a conveying space, where the material to be dried is conveyed. The dry- ing gas space is divided into compartments. The drying gas is directed through the dryer in such a way, that it flows from one compartment into another at least along one path. At least between some compartments the drying gas flows via the conveying space and at the same time through the material to be dried that is conveyed therein. When it is referred to upper or lower side or similar. directions in the text, a situation is described, where the dryer according to the invention is in its operating position.
The dryer for drying material according to an embodiment of the invention comprises the first end and the second end, and the material to be dried is provided to be fed to the dryer from the first end and to be discharged from the second end. The dryer comprises a conveying space for the conveying arrangement of the material to be dried, and when the dryer is in its drying position, the drying gas space is above the conveying space, and the drying gas space is divided into compart- ments, and the drying gas is provided to flow at least between some compartments through the conveying space. According to a preferred embodiment of the invention the conveying space is formed in a way that at least in some points it comprises positions where the drying gas flows through the material to be dried, when the conveying arrangement is conveying the material, that is, when the dryer is in operation. The conveying arrangement situated in the conveying space comprises at least a first screw conveyor and a second screw conveyor that are parallel, and between the said screw conveyors there is a longitudinal division wall, and in lower part of the division wall there is a formation that extends to the space between the screw conveyors and is provided to direct drying gas through the material to be dried. At least one path is provided for the drying gas through the dryer, where it flows alternating through the drying gas space and the conveying space. There may be also several paths, and they may be joined together or branched out. In an embodiment of the dryer according to the invention, drying gas is provided to be fed to at least one compartment of the drying gas space and to be discharged from at least one compartment of the drying gas space, which is not the same one, to which drying gas has been fed.
In another embodiment of the dryer according to the invention, the dryer compris- es at least one compartment of the drying gas space, from where drying gas is provided to be discharged from the conveying space, the compartments being provided in a way that the drying gas flows at least in a part of the conveying space upstream to the direction of motion of the material to be dried between said compartments. In a third embodiment of the dryer according to the invention, the dryer comprises at least one compartment of the drying gas space, from where drying gas is provided to move to the conveying space, and at least one compartment of the drying gas space, to which drying gas is provided to be discharged from the conveying space, the compartments being provided in a way that the drying gas flows at least in a part of the conveying space downstream to the direction of motion of the material to be dried between said compartments.
In a third embodiment of the dryer according to the invention, the dryer comprises at least one compartment of the drying gas space, from where drying gas is provided to move to the conveying space, and at least one compartment of the drying gas space, to which drying gas is provided to be discharged from the conveying space, the compartments being provided in a way that the drying gas flows at least in a part of the conveying space transversely to the direction of motion of the material to be dried between said compartments.
In a fifth embodiment of the dryer according to the invention, at least a part of the compartments of the drying gas space is provided in a way, that transfer of the drying gas into the conveying space and exit of the drying gas from the drying space are provided in a way, that the drying gas flows in the conveying space in several different directions in relation to the direction of motion of the material to be dried. Thereby, drying gas can be fed to several compartments of the drying gas space, or the drying gas has several paths to the conveying space from the compartment, to which drying gas is fed, or as a combination of the aforementioned.
In a sixth embodiment of the dryer according to the invention, at least a part of the openings of the cover structure comprises a screen arrangement or similar to pre- vent the material to be dried from entering the drying gas space. In a seventh embodiment of the dryer according to the invention, the drying gas is provided to flow at least between some compartments through openings in the cover structure, whereby the drying air exits from one compartment from an opening therein to the conveying space and enters from a conveying space to another compartment through an opening therein.
In an eighth embodiment of the dryer according to the invention, the screw system and the direction of rotation of the first screw conveyor and the second screw conveyor in the conveying arrangement in the conveying space are provided in a way that their outlet direction is between the screw conveyors. In a ninth embodi- ment of the dryer according to the invention, between the first and second screw conveyors in at least a part of the lower side of the conveying space there is an arrangement movable on rails in order to loosen possible clogging of the material to be dried. In a tenth embodiment of the dryer according to the invention, between the first and second screw conveyors in the bottom of the conveying space there is a shaping that is essentially in the shape of the outer surface of the screw conveyors.
In an eleventh embodiment of the dryer according to the invention, said shaping between the first and second screw conveyors is essentially in form of the outer surfaces of the screw conveyors and is above the shafts of the screw conveyors, when the dryer is in its operational position. In a twelfth embodiment of the dryer according to the invention, the inner surface of the conveying space is at least partly in form of the outer surface of the screw conveyor or screw conveyors.
In a thirteenth embodiment of the dryer according to the invention, when the dryer is in drying position, the first end of the dryer is situated lower than the second end. Thereby, the dryer is inclined. In a fourteenth embodiment of the dryer according to the invention, the water being condensed in the dryer is provided to run to the first end, which comprises a water discharge arrangement.
In a method according to an embodiment of the invention, a dryer with the first end and the second end is used for drying bulk material. The dryer used in the method comprises further a conveying space for the conveying arrangement of the material to be dried and a drying gas space, a cover structure, that is provided to separate the drying gas space and the conveying space, and the cover structure comprises openings between the drying gas space and the conveying space, and when the dryer is in its drying position, the drying gas space is above the conveying space, and the drying gas space is divided into compartments. According to a preferred embodiment of the invention, the conveying arrangement situated in the conveying space comprises at least a first screw conveyor and a second screw conveyor that are parallel, and between said screw conveyors there is a longitudinal separation wall, and in lower part of said separation wall there is a shaping that extends to the space between the screw conveyors and is provided to direct the drying gas through the material to be dried. Further, the method comprises steps, in which the material to be dried is fed at the first end of the dryer to the conveying space, where the conveying arrangement for conveying the materi- al to be dried is situated, the drying gas is fed to the drying gas space, the drying gas flows at least between some compartments through the conveying space travelling guided by the shaping in the lower part of said longitudinal separation wall through the material to be dried conveyed by the conveying arrangement, and the material to be dried is discharged out of the dryer at the second end of the dryer.
In an embodiment of the method according to the invention, the first end of the dryer is lower than the second end, and the drying gas conveys the water vapour separated from the material which is dried at the upper part of the dryer to the lower part of the frame, where the water vapour is condensed onto the surface of the material to be dried and thereby releases heat to the material to be dried. An advantage of the invention is that by it a dryer is provided that can, when necessary, be used continuously, quickly and cost-effectively. This enables, for example, industrial production of biofuel from material to be dried. The invention further enables that in order to convey the drying gas through the dryer and at the same time through the material to be dried such a high pressure difference is not necessary than in dryers according to the prior art.
An advantage of the dryer is that by means of it a dryer, drying material in industrial scale and being movable can be provided.
An advantage of the invention is further that by means of it the whole drying or pre-drying of the material can be performed.
Further, an advantage of the invention is that it is applicable to different types of materials to be dried.
An advantage of the invention is further, that it enables simple adjusting of the dryer when the humidity of the material to be dried varies. DESCRIPTION OF THE FIGURES
In the following, the invention will be described in detail. In the description, reference is made to the enclosed drawings, in which
Figure 1 shows by way of example an arrangement for drying material, with a dryer according to the invention, Figure 2 shows by way of example a perspective view of the dryer according to
Figure 1 , where some of the side wall of the dryer is removed,
Figure 3 shows by way of example the conveying space of the dryer according to Figure 1 ,
Figure 4 shows by way of example the dryer according to Figure 1 ,
Figure 5 shows by way of example the movements of the drying gas between the drying gas space and conveying space of a dryer according to a second invention,
Figure 6 shows by way of example the movements of the drying gas between the drying gas space and conveying space of a dryer according to a third invention, Figure 7 shows by way of example the movements of the drying gas between the drying gas space and conveying space of a dryer according to a fourth invention,
Figure 8 shows by way of example the cross-section of the dryer according to a fifth invention and the movements of the drying gas,
Figure 9 shows by way of example the movements of the drying gas between the drying gas space and conveying space of a dryer according to a sixth invention.
DETAILED DESCRIPTION OF FIGURES
The embodiments in the following description are given as examples only, and a person skilled in the art may realize the basic idea of the invention also in some other way than what is described in the description. Though the description may refer to a certain embodiment or embodiments in several places, this does not mean that the reference would be directed towards only one described embodiment or that the described characteristic would be usable only in one described embodiment. The individual characteristics of two or more embodiments may be combined and new embodiments of the invention may thus be provided.
Figure 1 shows an example of the arrangement for drying material, with a dryer 100 according to the invention. The arrangement comprises a store of the material to be dried 102, a conveying arrangement for the material to be dried 101 , a support arrangement 105, a heating device of the drying gas 103, and an additional dryer 104.
The material to be dried is kept in a reservoir 102 of the material to be dried. The storage may be fixed, such as a silo, or movable, such as for example a pallet or a container. The dryer and the peripheral devices related to it may be moved to the vicinity of the storage of the material to be dried, or the storage may be brought to the vicinity of the dryer. The material to be dried may be organic, such as for example, chopped firewood or wood chips. It may also be gravel or sand. The mate- rial to be dried may also be a mix of a suspension^and some bulk material. Preferably, the material to be dried is bulky. The material to be dried is conveyed by the conveying arrangement 101 from the storage of the material to be dried 102 to the dryer 100. The dryer is set into drying position by means of support arrangement 05. In a case according to the example the dryer is in an inclined position by means of a support arrangement, and the material to be dried is fed to the lower end. If the dryer is, for example, in horizontal position, the support arrangement is not necessarily required. The position of the dryer can also be varied with the support arrangement. In the dryer, the material to be dried is dried by means of drying gas. The gas is preferably air, but it may also be some inert gas, such as nitrogen. The gas is preferably heated. The gas is heated by a heating device 103 of the drying gas. In some cases, the drying gas does not have to be heated, but the gas flow is sufficient. Some prior art is used for heating the gas. The material to be dried that has passed through the dryer is discharged at the other end of the dryer than from which it was fed thereto. In the case according to the example, the dryer 100 according to the invention functions as a pre-dryer, and the final drying is performed in an additional dryer 104. The additional dryer may be, for example, a dryer where a vertical mattress is formed from the material to be dried, and through which drying gas is blown. The additional dryer may also be of different kind. One possible arrangement is to locate two or more dryers according to the invention one after another, which dry- ers have been adapted to dry materials with different humidities. Drying of the material to be dried can naturally be performed by using only the drying according to the invention. Thereby, an additional dryer is not necessary.
Figure 2 shows an example of the dryer 100 according to the invention that is used in an arrangement according to Figure 1. The dryer is shown in a perspec- tive view, where some of the side wall of the dryer is removed in order to increase clarity. The dryer comprises a frame that protects and supports the dryer. The dryer comprises the first end 208 and the second end 20 . The dryer comprises a drying gas space 204 and a conveying space 202. When the dryer is in its drying position, the drying gas space is above the conveying space. In a case according to Figure 2, the drying position of the dryer is an inclined position, whereby the first end of the dryer is lower than the second end. The drying position of the dryer may also be some other position. It may be in horizontal position or positioned such that its first end is higher than the second end.
The material to be dried travels in the dryer through the conveying space 202. Also the drying of the material to be dried is performed in the conveying space. The material to be dried is fed to the dryer and the conveying space at the first end of the dryer. In the example according to the Figure, above the frame of the dryer there is an opening 205, through which material to be dried can be dropped through the drying gas space 204 to the conveying space. The conveying space comprises a conveying arrangement for conveying the material to be dried through the dryer from the first end to the second end. The conveying arrangement can be realized, for example, by a conveyor belt, moving plates, screw conveyors or similar arrangements or combinations thereof, that are able 1o convey material to be dried and at the same time enable drying gas passing through the material to be dried at least in parts of the conveying space. In the example of Figure 2, two screw conveyors are used: the first screw conveyor 210 and the second screw conveyor 211. The screw conveyors are parallel and in direction of the conveying space and extend through the whole conveying space. The conveying space and the screw conveyors are arranged such that no material to be dried remains in the conveying space. This has been able to be realized by shaping of the surfaces of the conveying space and positioning of the screw conveyors. The screw system, that is, the thread and direction of rotation of the screw conveyors is provided in a way that their outlet direction is between the screw conveyors, that is, material is transferred between the screw conveyors. Thereby, if for example the threads of the screw conveyors are differently handed, they rotate in dif- ferent directions. Since the screw conveyors are parallel, the material to be dried is transferred from one screw conveyor to another. For transferring the material there is an opening or openings or space is provided between the screw conveyors. At some points between the screw conveyors there may be support structures or walls that extend from the bottom of the conveying space to its ceiling. The drying gas space 204 is divided into compartments 203. Drying gas is fed to at least one compartment of the drying gas space, and it is discharged out of at least one compartment of the drying gas space, and these compartments are different compartments. These compartments are not connected to each other through the drying gas space. Pressure difference is provided between the feed- ing and discharge points of the drying gas, so that the drying gas aims at flowing from the feeding point to the discharge point. The drying gas flows in the dryer 100 in a way that at least between some compartments of the drying gas spaces the drying gas flows through the conveying space 202, and when the dryer is in operation, at the same time through the material to be dried, conveyed by the conveying arrangement, drying it. Thus, the drying gas flows through the dryer along a path, where it is in the drying gas space and in the conveying space, alternatively. The drying gas space is essentially tight, such that the drying gas can escape the drying gas space only at predetermined points. Some compartments of the drying gas space may be connected to each other without the drying gas entering the conveying space. These compartments do not need to be adjacent. The compartments are separated by walls that may comprise openings or other arrangements, such as pipes or passages, for directing the drying gas from one compartment to another. The compartments may comprise a floor that may comprise one or several holes, or the bottom of the compartment may be open, thus forming an opening of the size of the compartment from the drying gas space to the conveying space. In a case according to the example of Figure 2, the drying gas is fed to a compartment situated in the vicinity of the second end 201 of the dryer, and it is discharged from the dryer from the compartment 207 situated in the vicinity of the first end 208 through opening 206. The opening may comprise an auxiliary pump for improving the pressure difference between the ends of the dryer, or it may comprise a filter for removing dust or similar. In the example, drying gas flows into the compartment 209, through which material to be dried is fed to the dryer. The gas may flow, for example, either from a previous compartment of the drying gas space or from the conveying space 202 from the wall of compartment 209 or through an opening in the floor (not shown). In the bottom of the compartment 209, in the part of the first end 208 side, there is an opening 212, through which the material to be dried gets into the conveying space. The drying gas flows from compartment 209 to the next compartment 207 through the conveying space and, at the same time, through the material to be dried.
A cover structure may exist between the drying gas space 204 and the conveying space to separate said spaces. The cover structure comprises openings, through which the drying gas flows from a compartment of the drying gas space into the conveying space, or vice versa. The cover structure of the dryer may also be realized in a way that the bottom of some compartments of the drying gas space is open and the one of some compartments it is closed, or the bottom of all com- partments is open. The cover structure forms the bottom of the drying gas space and the roof of the conveying space.
Figure 3 shows an example of a part of the conveying space 202 of the dryer according to Figure 1. The conveying space comprises the first screw conveyor 210 and the second screw conveyor 211. The conveying space comprises surface 301. The surface may be a part of the frame, or it may be at least partly separated from it. At the lower corners of the conveying space, the surface is formed to fol- low the shape of the outer edge, that is the screw thread, of the screw conveyors. Thus, remaining of regions in the conveying space where material to be dried would accumulate is avoided. In the example of Figure 3, the surface of the conveying space between the screw conveyors is essentially flat. In order to remove possible clogs formed between the screw conveyors, this space may comprise a movable arrangement that removes the clogs and moves material to be dried to be conveyed by the screw conveyors. This movable arrangement may, for example, be a plough-like plate structure or similar, moving on a rail.
The portion of the conveying space 202, shown in Figure 3, comprises two open- ings between the conveying space and the drying gas space: the first opening 304 and the second opening 303. The conveying space further comprises structures for directing the passage of the gas in the conveying space. In the example, these include a first transversal separation wall 305, a second transversal separation wall 307 and a longitudinal separation wall 306. The first opening is at the position of the first screw conveyor, and the second opening is at the position of the second screw conveyor. The openings are in connection with two different compartments of the drying gas space that are not connected to each other via the drying gas space. In this example, the upper portion of the opening is essentially of the size of a compartment of the drying gas space, and the lower portion of the opening is smaller than the upper portion of the opening. The openings may comprise screens or similar to prevent the material to be dried from getting into the drying gas space. The first opening is limited by the surface 301 of the conveying space, the first transversal separation wall 305 and the longitudinal separation wall 306. The second opening is limited by the surface 301 of the conveying space, the second transversal separation wall 307 and the longitudinal separation wall 306. The longitudinal separation wall is parallel to the direction of the screw conveyors and essentially in the region between the screw conveyors. In the case according to the example, it widens out towards the screw conveyors, that is, it narrows the width of the lower portion of the openings. In the lower portion of the longitudinal separation wall there is a shaping 302 that extends to the space between the screw conveyors. The shaping is essentially in the form of the outer surface of the screw conveyors. The shaping is for directing the movements of the drying gas in the conveying space. The shaping guides the drying gas in a way that it does not flow between the screw conveyors through a void space possibly formed above their shaft level, but is directed onto such a path that it passes through the material to be dried, when it exists in the conveying space. Thus, between the screw conveyors there is an opening or space, through which the mate- rial to be dried is transferred from one screw conveyor to another. The transversal walls exist to prevent the drying gas from flowing in longitudinal direction above the material to be dried. Although in the examples shown in the Figures this is the case, the first and the second transversal wall do not need to be at corresponding points at the positions of the first and the second screw conveyor. Further, transversal walls do not need to exist in the same number at different screw conveyors. The transversal walls and the longitudinal separation wall form compartments in the conveying space. The drying gas is provided to flow between these compartments of the conveying space in a way that it passes through the material con- veyed by the screw conveyors. This may be provided such that the gas flows between the compartments of the conveying space in direction of the screw conveyor, that is, it flows under the transversal wall or flows transversely to the screw conveyors, whereby it flows under the longitudinal separation wall. Directing of the drying gas is realized by positioning of the openings of the cover structure. The gas-directing structures of the conveying space can be realized in several different ways. These can be realized, for example, by using a longitudinal separation wall and its openings or transversal walls or a combination of both.
Figure 4 shows an example of the dryer according to Figure 1. The figure shows the positioning of the conveying space 202 and the drying gas space 204 of the dryer in relation to each other, and an example of the path of the drying gas in the dryer. Direction of the movement of the material to be dried in the dryer is indicated with an arrow 403. The drying gas space comprises compartments that are separated from each other by walls. In this example, the walls are situated at the walls of the conveying space shown in Figure 3 such that they form extensions to each other. In Figure 4, the first compartment 401 and the second compartment 402 are indicated. In the figure, movements of the drying gas are indicated by a broken line. From the first compartment the drying gas flows to the conveying space. This is indicated by a broken line arrow pointing downwards. The drying gas flows to direction of lower pressure in the conveying space. This can be guid- ed by positioning the walls of the conveying space and the openings of the drying gas space in order to provide the desired gas flow. The gas flow is arranged according to the desired properties of the dryer. In the example, this direction of lower pressure is in the direction of the opening situated at the second compartment in the conveying space. Thus, the drying gas flows in the stream of the ma- terial to be dried transversely to its movement. The drying gas moves to the second compartment of the drying gas space from the conveying space through the opening at the second compartment. Movement of the drying gas is indicated by a broken line arrow pointing upwards. From the second compartment of the drying gas space the drying gas moves to the next compartment (not shown) through an opening (not shown) in the wall of the second compartment. This movement of the drying gas is indicated by a curved broken line arrow. Figure 5 shows an example of the movements of the drying gas between the drying gas space and conveying space of a dryer according to the second invention. The dryer is shown from above, and the direction of the material to be dried in the dryer is indicated by a thick line. The drying gas space is divided into compartments, and the drying gas flows between the compartments either directly, from one compartment to another or through the conveying space. In the figure the continuous line arrows represent the movement of the drying gas between the compartments of the drying gas space, and the broken line arrows represent the movement of the drying gas in the conveying space between the compartments of the drying gas space. The drying gas is fed to the compartment 501 of the drying gas space, and it is discharged from the dryer from the compartment 504 of the drying gas space. In floors of some compartments there is an opening 502 to the conveying space. In the example, in the floor of one compartment 503, there are two openings. Thereby, between the openings in the conveying space there may be a transversal separation wall. The gas flows through compartment 503. The flow of gas in the drying space is guided by transversal separation walls, a longitudinal separation wall and its possible openings, or both. In this example, compartments and openings are provided such that in the portion of the dryer that is closer to the end, from where the material to be dried is discharged from the dryer, the drying gas flows in the conveying space against the flow direction of the material to be dried. In the portion of the dryer that is closer to the end, where the material to be dried is fed to the dryer, the drying gas flows in the conveying space essentially transversely to the flow direction of the material to be dried. Thus, the drying gas can have movements in two different directions in the conveying space. Naturally, several different paths and path combinations can be provided for the drying gas.
Figure 6 shows an example of the movements of the drying gas between the drying gas space and conveying space of a dryer according to the third invention. Markings and viewing direction are the same as those in Figure 5. The drying gas is fed to the compartment 601 of the drying gas space, and it is discharged from the dryer from the compartment 603 of the drying gas space. There are openings 602 in the floors of the compartments, except for the discharge compartment 603. The compartments of the drying gas space are positioned one after another, and the drying gas flows in the conveying space in opposite direction to the movement of the material to be dried.
Figure 7 shows an example of the movements of the drying gas between the dry- ing gas space 706 and conveying space 707 of a dryer according to the fourth invention. The dryer is viewed from the side. The dryer comprises the first end 711 and the second end 710. Movement of the material to be dried through the dryer in the conveying space is indicated by arrow 709. Movements of the drying gas are indicated by broken line arrows 713. In its operation, the dryer is in hori- zontal plane. In this example, the compartments of the drying gas space 706 are on two levels. The upper level 714 is in the upper portion of the dryer, and the lower level 715 is between the upper level of the drying gas space and the conveying space. On the upper level of the drying gas space there is a feeding compartment 701 , a delivery compartment 702 and a discharge compartment 705. On the lower level of the drying gas space there is the first compartment 712, the second compartment 703, the third compartment 704, the fourth compartment 716 and the fifth compartment 717. Between the drying gas space and the conveying space 707 there is a cover structure 708, which comprises openings at the position of the compartments of the lower level.
The drying gas is fed to the feeding compartment 701. From the same source of drying gas, drying gas can be fed to the delivery compartment 702. In the bottom of the feeding compartment there is an opening, from where the drying gas can get into the first compartment 712 of the lower level. From there the drying gas gets from an opening in the cover structure 708 into the conveying space 706. The drying gas flows against the direction 709 of the material to be dried and leaves the conveying space to the second compartment 703 from an opening in the cover structure. In the cover structure, at the second compartment, there is a second opening, from which the gas gets into the conveying space, through which it gets to flow into the third compartment 704, at which the cover structure, in the same way, comprises two openings, through which the drying gas flows correspondingly to how it does flow from the openings at the second compartment. Also the fourth compartment 717 is similar to the second compartment, except that it comprises an arrangement, for example an opening, by means of which more drying air is brought to the fourth compartment through delivery compartment 702. From the fourth compartment the drying gas flows through the conveying space into the fifth compartment 713, at which the cover structure comprises one open- ing. From the fifth compartment the drying gas moves to the discharge compartment 705, from where the drying gas is discharged from the dryer. By means of a two-level drying gas space the drying gas can be guided to desired spots in the dryer and the path of the drying gas can be adjusted. The two-level model can be realized in several other ways than the one described in the example.
Figure 8 shows an example of the conveying space of a dryer according to the fifth invention in a cross-section and movements of the drying gas at the point in question. The movements of the drying gas are indicated by broken line arrows. The conveying space comprises the first 802 and the second screw conveyor 806, that are parallel and in direction of the conveying space. The surface 801 of the conveying space is essentially in the form of the outer surface of the screw conveyors. In the space between the screw conveyors, below and above the level between the axes of the screw conveyors there are shapings: upper shaping 803 and lower shaping 804. The surfaces of said shapings are essentially in the form of the outer surfaces of the screw conveyor such that there remain as few void spaces as possible, when material to be dried is conveyed through the dryer. An opening 805 remains between the shapings, through which opening the drying gas can flow. In some embodiments, the opening between the shapings may be above or below the level between the axes of the screw conveyors, that is one or the other of the shapings extends over said level. In the example, the screw conveyors rotate in a way that the material to be dried, conveyed by them, tries to get through the opening from both screw conveyors to the other screw conveyor. Thus, the material to be dried remains in motion and is not allowed to clog on one or the other screw conveyor. In the example, drying gas gets from the drying gas space to the conveying space through the opening situated above the second screw conveyor. The drying gas flows through the material to be dried, conveyed by the thread of the screw conveyor and passes through the opening 805 to the first screw conveyor. There, the drying gas passes through the material to be dried, conveyed by the thread through the opening above the first screw conveyor back to the drying gas space, but to a different compartment than from where it came. Flow of the drying gas is directed towards smaller pressure. Path of the drying gas can be guided, that is, pressure differences can be adjusted by means of the structures of the conveying space, of which examples are given in connection with Figure 3. Figure 9 shows an example of the movements of the drying gas between the drying gas space and conveying space of a dryer according to the sixth invention. Movements of the drying gas in the drying gas space are indicated by an arrow with a continuous line, and in the conveying space by an arrow with a broken line. In this example, the feeding compartment 905 of the drying gas is in the middle portion of the dryer, and there are two discharge compartments: the first dis- charge compartment 901 and the second discharge compartment 906, that are at the ends of the dryer. The compartments of the drying gas space comprise openings 904, through which the drying gas flows to the conveying space, and openings 902, through which the drying gas flows from the conveying space into the drying gas space. From the feeding compartment 905 the drying gas flows in the drying gas space to two other compartments and through the conveying space to one compartment. From these compartments the drying gas proceeds to the next compartment in a way that the drying gas flows in the conveying space essentially transversely to the movement of the material to be dried. The paths of the drying gas according to the example in the drying gas space may be realized, for exam- pie, by means of a two-level drying gas space, described in Figure 7.
Above, some preferred embodiments according to the invention have been described. The invention is not limited to the solutions described above, but the inventive idea can be applied in numerous ways within the scope of the claims.

Claims

Claims
1. Dryer (100) comprising the first end (208; 7 1 ) and the second end (201 ; 710), and the material to be dried is provided to be fed to the dryer from the first end and to be discharged from the second end, and the dryer comprises a con- veying space (202; 706) for the conveying arrangement of the material to be dried, and a drying gas space (204; 705), and when the dryer is in its drying position, the drying gas space is located above the conveying space, a cover structure (708) that is provided to separate the drying gas space (204; 705) and the conveying space (202; 706), and the cover structure comprises openings (502; 602; 902, 904) between the drying gas space and the conveying space, and the drying gas space is divided into compartments (203, 207, 209; 501 , 503, 504; 601 , 603; 701 , 702, 703, 704; 901 , 903, 905, 906), and the drying gas is provided to flow between at least some compartments of the drying gas space through the conveying space, characterized in that the conveying arrangement located in the con- veying space (202; 706) comprises at least the first screw conveyor (210; 802) and the second screw conveyor (211 ; 806), that are parallel, and between said screw conveyors there is a longitudinal separation wall (306), and the lower portion of said separation wall comprises a shaping (302; 806), that extends to the space between the screw conveyors and is provided to direct drying gas through the material to be dried.
2. Dryer (100) according to the Claim 1 , characterized in that drying gas is provided to be fed to at least one compartment (501 ; 601 ; 701 ; 901 ) of the drying gas space (204; 705) and to be discharged from at least one compartment (207; 504; 603; 704; 901 , 906) of the drying gas space that is a different compartment from the one to which drying gas was fed.
3. Dryer (100) according to Claim 2, characterized in that the dryer comprises at least one compartment (209) of the drying gas space (204; 705), from where drying gas is provided to move to the conveying space (202; 706), and at least one compartment (207) of the drying gas space, to which drying gas is provided to be discharged from the conveying space, which compartments are provided in a way that the drying gas flows at least in a part of the conveying space upstream to the direction of motion of the material to be dried between said compartments.
4. Dryer (100) according to Claim 2, characterized in that the dryer comprises at least one compartment of the drying gas space, from where drying gas is pro- vided to move to the conveying space (202; 706), and at least one compartment of the drying gas space, to which drying gas is provided to be discharged from the conveying space, which compartments are provided in a way that the drying gas flows at least in a part of the conveying space downstream to the direction of motion of the material to be dried between said compartments.
5. Dryer (100) according to Claim 2, characterized in that the dryer comprises at least one compartment of the drying gas space, from where drying gas is provided to move to the conveying space (202; 706), and at least one compartment of the drying gas space, to which drying gas is provided to be discharged from the conveying space, which compartments are provided in a way that the drying gas flows at least in a part of the conveying space essentially transversely to the di- rection of motion of the material to be dried between said compartments.
6. Dryer (100) according to Claim 2, characterized in that at least a part of the compartments of the drying gas space is provided in a way, that moving of the drying gas into the conveying space (202; 706) and exit of the drying gas from the drying space are provided in a way, that the drying gas flows in the conveying space in several different directions in relation to the direction of motion of the material to be dried.
7. Dryer (100) according to the Claim 6, characterized in that at least a part of the opening (502; 602; 902, 904) of the cover structure (708) comprises a screen arrangement or similar to prevent material to be dried from getting into the drying gas space (204; 705).
8. Dryer (100) according to one of Claims 6-7, characterized in that the drying gas is provided to flow at least between some compartments through openings (502; 602; 902, 904) in the cover structure (708), whereby the drying air exits from one compartment from an opening therein to the conveying space (202; 706) and enters from a conveying space to another compartment through an opening therein.
9. Dryer (100) according to one of Claims 1-8, characterized in that the screw system and direction of rotation of said first screw conveyor (210; 802) and second screw conveyor (211 ; 806) is provided such that their outlet direction is be- tween the screw conveyors.
10. Dryer (100) according to Claim 9, characterized in that between the screw conveyors (210, 211 ; 802, 803) in at least a part of the lower side of the conveying space (202; 706) there is an arrangement movable on rails in order to loosen possible clogging of the material to be dried.
11. Dryer (100) according to Claim 9, characterized in that between the first (210; 802) and second screw conveyors (211 ; 803) in the bottom of the conveying space (202; 706) there is a shaping (804) that is essentially in the form of the outer surface of the screw conveyors. 12. Dryer (100) according to one of Claims 9-11 , characterized in that said shaping (302; 803) between the first (210; 802) and second screw conveyors (211 ; 803) is essentially in the form of the outer surfaces of the screw conveyors and essentially above the level formed by the axes of the screw conveyors, when the dryer is in its operational position. 13. Dryer (100) according to one of Claims 8-12, characterized in that the inner surface (301 ; 801 ) of the conveying space (202; 706) is at least partly in the form of the outer surface of the screw conveyor or screw conveyors (210, 211 ; 802, 803). 4. Dryer (100) according to one of Claims 1- 3, characterized in that when the dryer is in drying position, its first end (208; 711 ) is lower than the second end
(201 ; 710).
15. Dryer (100) according to Claim 14, characterized in that the water being condensed in the dryer is provided to run to the first end (208; 711 ), which comprises a water discharge arrangement. 16. Method for drying material, in which method a dryer (100) is used, which comprises the first end (208; 711 ) and the second end (201 ; 710), and the dryer comprises a conveying space (202; 706) for the conveying arrangement of the material to be dried, and a drying gas space (204; 705), a cover structure (708) that is provided to separate the drying gas space (204; 705) and the conveying space (202; 706), and the cover structure comprises openings (502; 602; 902, 904) between the drying gas space and the conveying space, and when the dryer is in its drying position, the drying gas space is above the conveying space, and the drying gas space is divided into compartments (203, 207, 209; 501 , 503, 504; 601 , 603; 701 , 702, 703, 704; 901 , 903, 905, 906), characterized in that the con- veying arrangement located in the conveying space (202; 706) comprises at least the first screw conveyor (210; 802) and the second screw conveyor (211 ; 806), that are parallel, and between said screw conveyors there is a longitudinal separation wall (306), and the lower portion of said separation wall comprises a shap- ing (302; 806), that extends to the space between the screw conveyors and is provided to direct drying gas through the material to be dried, and the method comprises steps, where
- the material to be dried is fed at the first end to the conveying space that comprises a conveying arrangement for conveying the material to be dried
- the drying gas fed to the drying gas space
- the drying gas flows at least between some compartments through the conveying space travelling guided by the shaping in the lower part of said longitudinal separation wall through the material to be dried
- the drying gas is discharged from the drying gas space, and
- the material to be dried is discharged from the dryer at the second end of the dryer.
17. Method according to Claim 16, characterized in that the first end (208; 7 ) of the dryer is lower than the second end (201 ; 710), and the drying gas conveys the water vapour separated from the material which is dried at the upper part of the dryer to the lower part, where the water vapour is condensed onto the surface of the material to be dried and thereby releases heat to the material to be dried.
PCT/FI2013/050589 2012-06-06 2013-05-31 Dryer and method for drying material WO2013182744A2 (en)

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FI20125614A FI124272B (en) 2012-06-06 2012-06-06 DRYING AND PROCEDURE FOR DRYING MATERIALS
FI20125614 2012-06-06

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CN104848671A (en) * 2015-05-06 2015-08-19 爱森（中国）絮凝剂有限公司 Polyacrylamide dryer
CN107388803A (en) * 2017-06-28 2017-11-24 徐州市沅和牧业有限责任公司 A kind of herbage drying unit
CN111465501A (en) * 2017-12-06 2020-07-28 贺利氏特种光源有限公司 Method for drying a substrate, dryer module and dryer system for carrying out the method
CN111465501B (en) * 2017-12-06 2022-08-12 贺利氏特种光源有限公司 Method for drying a substrate, dryer module and dryer system for carrying out the method

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FI20125614A (en) 2013-12-07
EP2859292A2 (en) 2015-04-15
EP2859292A4 (en) 2016-07-13
WO2013182744A3 (en) 2015-05-07

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