DE102006024144A1 - Dryers for pourable drying material - Google Patents

Abstract

The present invention relates to a continuous dryer (1) for pourable drying material (6), with a conveyor line to be passed from the material to be dried (6) with at least one rotatable conveyor screw (2), in which the drying material (6) can be traversed by a gas. The new continuous dryer (1) is characterized in that the conveying path forming at least one rotatable screw conveyor (2) over its full circumference with a gas-permeable and well-impermeable jacket (20) is surrounded.

Description

The The invention relates to a continuous dryer for pourable Trocknungsgut, with a from the material to be dried to continuous conveyor line with at least a rotatable screw conveyor, in which the material to be dried can be flowed through by a gas.

One first continuous dryer of the type mentioned is from the Swiss Patent No. 485 993. This dryer has a plurality of mutually parallel, horizontally extending screw conveyors on, with each auger in a trough-shaped Tub is located. The lower area of each tray is at the outer diameter the screw conveyor customized rounded and provided with openings. Via one or more input devices With dosing screws, the material to be dried becomes the screw conveyor fed. By turning the screw conveyors the drying material to be dried is conveyed through the dryer. At the same time from the outside through the openings in the lower area of the trough-shaped trays passed a gas that flows through the drying material and this dries.

Another continuous dryer of the type mentioned is from the EP 0 165 916 A2 known. Here, a dryer is disclosed in which a screw conveyor is used to promote drying material, which is arranged above a perforated bottom. Through the bottom of a gas is passed, which flows through the drying material and this dries. The screw conveyor here consists of a relatively narrow helix, which is mounted radially on the outside of a tube assembly. The tube arrangement can be flowed through by a heat transport medium in order to additionally introduce heat as drying energy into the material to be dried in this way.

adversely is in both prior art dryers that a relatively large risk exists that in undesirable Parts of the drying material taken from the gas stream and be carried by the gas outlet, which leads to problems especially with light drying material. Around To avoid this, the Gas velocity can be limited to relatively low values, which However, a good efficiency of the dryer is detrimental. at the second known dryer is also disadvantageous that the screw conveyor is complicated, because they sealing rotary joints for the supply and discharge of the Heat transport medium needed. These rotary unions are wearing parts that regularly maintained or need to be replaced and to increased Costs lead.

For the present Invention is therefore the task of a dryer of the beginning to create the above-mentioned type, the above-mentioned disadvantages avoids and with a simple construction a reliable function offers high efficiency and in which an undesirable entrainment of Dividing the material to be dried into the gas stream flowing through the material to be dried is avoided.

The solution This object is achieved according to the invention with a dryer of the beginning mentioned type, which is characterized in that the conveyor line forming at least one rotatable screw conveyor over her full circumference with a gas-permeable and well-impermeable coat is surrounded.

With the dryer according to the invention Advantageously, a simple construction is achieved because of this no vulnerable Rotating Unions for a heat transport medium needed. The screw conveyor surrounding coat ensures that the drying material inside the screw conveyor remains even if the material to be dried is light and / or that Drying gas used at high speed the material to be dried flows through. This allows a high efficiency of the dryer, at the same time the risk of entrainment of parts of the drying material is avoided with the gas stream.

Prefers The dryer is a continuous-flow dryer with a steadily running Auger. In order to A continuous drying operation is possible for many Applications in continuously operating production or processing plants is advantageous.

alternative The dryer can use a batch dryer with one at a filling and Emptying the dryer will be ongoing auger, taking place during one Drying of the material to be dried, the conveyor screw resting or turns back and forth. The back and forth turning of the screw conveyor is used here, the drying material during drying without promoting it, which may be favorable for the drying process.

there Is it possible, that the Dryer with identical design, either alternatively or alternately in one of both modes of operation, ie continuous drying or batch drying, is operated, whereby he is flexible.

In a development of the dryer according to the invention is preferably provided that the jacket is attached to the screw conveyor and rotatable with this. In this way, any relative movement and any friction caused thereby between the screw conveyor on the one hand and the On the other hand completely avoided coat. Undesirable, leading to damage of the drying material leading grinding effects can not occur. Thus, the material to be dried is transported particularly gently by the screw conveyor, which is surrounded by the co-rotating jacket.

Further is preferably provided that the jacket from a grid-shaped or perforated material or a woven material, wherein the material is preferably metal or plastic. In all versions is achieved that the Coat on the one hand for the gas is sufficiently permeable and on the other hand for the material to be dried is sufficiently impermeable. The design of the Coatings and material selection depend on the requirements in an individual case, in particular according to the size of the individual particles of the Drying material and according to the temperatures to be used in the Drying.

Prefers is further provided that the screw conveyor with the jacket in a substantially gas-tight housing with at least one gas inlet and arranged at least one gas outlet is. Through the housing becomes the screw conveyor with the coat completely encapsulated, so that a targeted gas routing allows becomes and at the same time a danger the environment is excluded.

Further is for the dryer according to the invention suggested that the casing at least one sealed in drying operation, for cleaning and maintenance-releasable opening that the Auger is interchangeable and that through the at least one opening the Auger Removable and installable. In this embodiment, necessary Cleaning and maintenance work can be done easily. The interchangeability of the screw conveyor allows a simple and time-saving adaptation of the dryer different drying tasks, especially different Drying goods, the different augers require. If the jacket is connected to the screw conveyor, can this together with the auger be replaced in one operation. Thus, there is the possibility for one Dryer different screw conveyors or to keep different units out of feed screw and jacket, then installed according to the respective drying task in the housing become.

Prefers is the opening by a removable or adjustable top or side hood of the housing closable. With this configuration, the opening can be quick and easy open and be closed. At the same time the opening is easily accessible.

In Another embodiment is proposed that in the housing baffles for Leadership of Gas are arranged, by means of which the gas in the flow through the Trocknungsgut feasible is. With the baffles a particularly precise flow guidance is ensured so that thereby for one Consistent efficiency and a consistently good, reproducible Drying result is taken care of.

Around Energy losses and reductions in efficiency due to false flows of the gas to avoid, is further provided that the shell-side edges of the baffles with the interposition of sliding seals, preferably adjustable are, on the outer circumference of the coat. In this way, the gas flow is completely through the Coat introduced into the material to be dried, which is a ensures high efficiency of drying.

Further is inventively provided that the at least a gas inlet one Gas conditioning device is assigned or upstream. through the gas conditioning device can control the gas in its properties for the each intended drying purpose to be optimized, in particular be brought to a certain temperature and / or humidity.

As already mentioned above, that's the screw conveyor surrounding coat designed so that it is impermeable to the drying material. Nevertheless, you can but especially fine, dusty particles, which are contained in the drying material or during the Drying in the dryer, pass through the jacket. Around a discharge of this dust from the dryer into the environment it is expedient to avoid this at least one gas outlet Dust filter upstream or downstream.

Prefers is further provided that at least a gas inlet pressure blower is or upstream of and / or that the at least one gas outlet to a suction fan or is subordinate. With the fan or the blowers becomes the gas extraction caused by the dryer.

When using a pressure blower, a particularly high gas throughput is possible. In the arrangement of a suction fan on the side of the gas outlet is ensured that in the interior of the housing relative to the ambient pressure, there is a negative pressure. This ensures that gas and any dust contained therein from the inside of the housing can not escape into the environment, thereby protecting the environment from potentially harmful effects of the drying gas or dust from the dryer becomes.

For drying that must be Drying material from outside in the screw conveyor be introduced. So that in this way no disturbing ambient air into the interior of the screw conveyor and the housing passes or vice versa gas and / or dust escape, is preferred a first end of the screw conveyor an environment substantially gas-tight sealed input device assigned.

The Good input device includes prefers one in its capacity adjustable vibratory conveyor or an adjustable in their performance input screw as a metering device. This is a precisely metered feeding of drying material to be dried in the screw conveyor possible. Depending on requirements, the delivery rate changed the donation device be, for example, if the nature of the drying material to be dried or change its drying properties.

To the passage through the conveyor line must now Dry material to be dried from the screw conveyor and the housing dissipated become. Thus also in this way no false air in the case or Gas and / or dust to the outside can reach is appropriate one second end of the screw conveyor assigned to the environment substantially gas-tight sealed Gutausgabeeinrichtung.

A preferred option for gas-tight design of the Gutausgabeeinrichtung is that these with a lock, in particular a rotary valve is.

Around the screw conveyor on the one hand safe and on the other hand to store friction, is provided that the Auger a central, each frontally projecting axis or two frontal, protruding Has stub axle for screw bearing.

To the Turning the screw conveyor is provided that this by means of at least one drive motor via a gear or Reibrad- or Belt or chain drive is rotary drivable. In this way can the screw conveyor reliable be set in rotation, wherein by a speed adjustment of the motor, the speed of the screw conveyor is adjustable to suitable values. With suitable translation the transmission is sufficient even a relatively low drive power for the rotation of the screw conveyor and for the promotion of the drying material in the screw, resulting in a low Energy consumption of the dryer contributes.

Around also more complicated drying operations with the dryer according to the invention carry out to be able to beats an embodiment in that in the conveying direction the drying material seen the housing in several gas side of each other separate housing areas is divided, wherein through each housing area a separate gas flow feasible is. With that you can in the different housing areas different treatments of the drying material take place, wherein the gas flows z. As by their temperature, their speed or their composition can distinguish. In the simplest case, the gas streams are air streams, the air advantageous taken from the environment and after the drying process, preferably After passing through the dust filter, release again into the environment can be. Alternatively, a circulation of a gas is conceivable, for example of nitrogen. At execution with a gas cycle is still useful in this cycle a drying step for to integrate the gas.

A preferred embodiment provides that in the conveying direction of the material to be dried at least a first housing portion forming a drying zone, that of a warm drying gas stream flow through is, and that at least a second housing area a cooling zone that forms of a cool Gas stream is flowed through. In this way, in the at least one first housing portion the drying material are dried, wherein when using the warm Drying gas flow the drying material is necessarily heated. In the second housing area The drying material can be cooled down again to avoid damage one over increased too long a period Temperature of the material to be dried to avoid. It also gets through this for example, possible the drying material after drying and after the subsequent cooling immediately to pack without the Danger of a harmful Condensation exists.

Farther is for the dryer according to the invention preferably provided that the Auger is arranged horizontally. In this orientation results in a reliable and even promotion the material to be dried by the screw conveyor, the auger at the same time for a favorable forced mixing and circulation of the material to be dried. disorders in the drying material conveying, as for example in known vertical dryers with gravity of the drying material can occur safely avoided here.

Alternatively, there is the possibility that the screw conveyor is arranged inclined to the horizontal, wherein preferably the angle to the horizon maximum 45 °. Even in a limited inclined arrangement still a reliable and uniform promotion of the material to be dried is ensured by the screw conveyor. In the inclined arrangement is expedient Gutausgabeeinrichtung higher than the feed device, which z. B. facilitates the forwarding of the drying material to processing facilities or the immediate packaging of the material to be dried.

Except for drying purposes can the dryer of the invention also as a device for other tasks in the treatment of bulk goods by means of a gaseous medium be used, for example, if a bulk material intensive and possible Completely to be contacted with a gas. Conversely, in the device also the treatment of a gas by contact with a pourable material conceivable.

in the The following will be an embodiment of a dryer according to the invention explained with reference to a drawing. The figures of the drawing show:

1 a dryer in a schematic side view, partly in longitudinal section,

2 the dryer off 1 in a cross section through a first section of the dryer and

3 the dryer in a partial cross-section through its end.

As the 1 the drawing shows, has the dryer shown there 1 a horizontal screw conveyor 2 at their periphery of a coat 20 is surrounded. The screw conveyor 2 has a central axis 23 with which the screw conveyor 2 including the attached coat 20 rotatable in a substantially closed housing 3 is stored. The coat 20 is designed so that it is permeable to gas, but impermeable to a Trocknungsgut.

Left in 1 protrudes a left, first end 21 the screw conveyor 2 slightly above the local front end of the housing 3 out. At this first end area 21 the screw conveyor 2 is drying material to be dried via a feed device 4 steady and metered into the screw conveyor 2 brought in. The donation device 4 For example, includes an adjustable or adjustable vibratory conveyor, which via a delivery pipe 40 the first in the donation device 4 poured in drying material in the screw conveyor 2 initiates. The front end of the screw conveyor 2 and the coat 20 is here by an elastic front disc 41 with a central opening for the conveyor pipe 40 locked. With the delivery pipe 40 forms the frontal disk 41 a simple, but sufficient rotary seal. The outside of the case 3 lying short auger and shell section is well-sealed and gas-tight at the periphery.

By rotation of the screw conveyor 2 by means of one at the other, in 1 right end area 22 arranged drive motor 24 The material to be dried is forced in the conveying direction 25 through the dryer 1 promoted.

To dry the material to be dried, a gas, for example air, is used, which through here a total of three gas inlets 30 in the interior of the case 3 to be led. Inside the case 3 the gas streams are each guided so that they the screw conveyor 2 flow through the drying material therein substantially in the transverse flow, wherein moisture contained in the Trocknungsgut is taken from the gas stream. The gas streams are over here two gas outlets 32 from the dryer 1 dissipated. The gas outlets 32 one or more dust filters may be upstream or downstream.

To promote the gas flows serve one or more fans, which are not shown in the drawing figure; the fans are z. B. designed as a suction fan and the gas outlets 32 assigned or downstream to inside the case 3 create a negative pressure relative to the environment. This vacuum avoids a discharge of Staubgut from the interior of the housing 3 in the nearby areas.

At the in 1 shown example of the dryer 1 owns the housing 3 three housing areas, namely two first housing areas 3.1 and 3.1 'and a second housing area 3.2 , The first two housing areas 3.1 , and 3.1 ' serve to dry the material to be dried with a heated gas, such as warm air, while the second housing portion 3.2 used here for cooling the previously heated during drying drying material. This is done by the second housing area 3.2 a cool gas stream, z. B. a cooled air flow, out.

The dried and re-cooled drying material then leaves in the second, in 1 right end area 22 the screw conveyor 2 the dryer 1 via a good output device arranged there 5 , In this Gutausgabeeinrichtung 5 For example, a lock, such as rotary valve, integrated to a gas or air passage through the Gutausgabeeinrichtung 5 to avoid. Through an output hopper 50 the dried material to be dried falls down from the good dispensing device 5 and can be used, for example, directly in transport or storage container bottled or fed to another conveyor line for any further processing required.

In drying operation is the housing 3 of the dryer 1 closed to ensure the desired gas flows. For maintenance and repair purposes, the housing 3 be opened by a top hood here 35 pivoted or completely removed. Through the then open top of the housing 3 becomes the interior of the case 3 accessible. In addition, in the open state of the housing 3 the screw conveyor 2 including her coat 20 be replaced quickly and easily. That way, the dryer can 1 with different screw conveyors 2 and different coats 20 be equipped to the dryer 1 to adapt to different drying tasks, in particular different dry goods.

Besides, the dryer is 1 expediently associated with a not specifically shown in the drawing control device, with the operation of the dryer 1 is monitored and controlled, in particular by moisture and temperatures detected gas temperatures, gas volumes and / or gas velocities regulated and the delivery rate of the feed device 4 and the screw conveyor 2 be regulated as needed.

2 shows the dryer 1 in cross section through the first housing portion 3.1 , In the center of the housing 3 is the screw conveyor 2 with the surrounding coat 20 , Inside the screw conveyor 2 and the coat 20 Here is the drying material 6 shown. By the rotation of the on-axis 23 mounted screw conveyor 2 and its mantle 20 is the pourable material to a limited extent in the direction of rotation of the screw conveyor 2 taken along, causing the in 2 visible sloping surface of the material to be dried 6 formed.

Right below in 2 is a gas inlet 30 recognizable by the gas, z. B. heated air, in a gas channel 31 inside the case 3 can be introduced. The gas channel 31 leads, according to the position of the drying material 6 in the screw conveyor 2 to which in 2 pointing down to the left peripheral portion of the screw conveyor 2 and the coat 20 and there allows a transfer of the gas flow from the gas channel 31 through the coat 20 through into the inside of the screw conveyor 2 and in this way through the drying material 6 therethrough. Inside the case 3 is the gas channel 31 through baffles 33 limited. Sheath-side edges of the baffles 33 lie under the interposition of sliding seals 34 and 34 ' on the outer circumference of the jacket 20 to the gas flow as completely as possible through the Trocknungsgut 6 respectively.

After flowing through the drying material 6 in the screw conveyor 2 the gas flow flows up through the jacket 20 through the gas outlet 32 from.

The upper section of the auger 2 gets through the hood 35 covered, which is a pivotable or removable part of the housing 3 forms.

3 finally shows the in 1 right end area 22 the screw conveyor 2 with the arranged there Gutausgabeeinrichtung 5 , In the upper part of the 3 is the rear end of the screw conveyor seen in the conveying direction 2 with the central axis 23 visible, noticeable. With its lower part lies the auger 2 with her coat 20 in the Gutausgabeeinrichtung 5 , Through a frontally open area of the screw conveyor 2 The dried material to be dried enters the hopper 50 and falls through this under gravity down, for example, in a transport or storage container or on another conveyor line.

1

Continuous dryer

2

Auger

20

coat

21 22

End areas of 2

23

axis

24

drive motor

25

conveying direction

3

casing

30

gas inlet

31

gas channel

32

gas outlet

33

baffles

34 34 '

sliding seals

35

Hood

3.1 3.1 '

first housing areas

3.2

second housing area

4

Good input device

40

delivery pipe

5

Gutausgabeeinrichtung

50

output hopper

6

be dried

Claims (23)

Continuous Dryer ( 1 ) for pourable drying material ( 6 ), with one of the drying material ( 6 ) to be passed through conveyor line with at least one rotatable screw conveyor ( 2 ), in which the drying material ( 6 ) is traversed by a gas, characterized in that the conveying path forming at least one rotatable screw conveyor ( 2 ) over its full circumference with a gasdurchläs and impermeable coat ( 20 ) is surrounded. Continuous dryer according to claim 1, characterized in that the jacket ( 20 ) on the screw conveyor ( 2 ) is mounted and rotatable with this. Continuous dryer according to claim 1 or 2, characterized in that the jacket ( 20 ) consists of a latticed or perforated material or a fabric material, wherein the material is metal or plastic. Continuous dryer according to one of the preceding claims, characterized in that the screw conveyor ( 2 ) with the coat ( 20 ) in a substantially gas-tight housing ( 3 ) with at least one gas inlet ( 30 ) and at least one gas outlet ( 32 ) is arranged. Dryer according to one of the preceding claims, characterized in that the jacket ( 20 ) consists of a latticed or perforated material or a fabric material, wherein the material is metal or plastic. Dryer according to one of the preceding claims, characterized in that the screw conveyor ( 2 ) with the coat ( 20 ) in a substantially gas-tight housing ( 3 ) with at least one gas inlet ( 30 ) and at least one gas outlet ( 32 ) is arranged. Dryer according to claim 6, characterized in that the housing ( 3 ) has at least one closed in the drying operation, releasable for cleaning and maintenance opening, that the screw conveyor ( 2 ) is interchangeable and that through the at least one opening, the screw conveyor ( 2 ) can be removed and installed. Dryer according to claim 7, characterized in that the opening by a removable or adjustable top or side hood ( 35 ) of the housing ( 3 ) is closable. Dryer according to one of claims 6 to 8, characterized in that in the housing ( 3 ) Baffles ( 33 ) are arranged for guiding the gas, by means of which the gas in the cross flow through the Trocknungsgut ( 6 ) is feasible. Dryer according to claim 9, characterized in that shell-side edges of the baffles ( 33 ) with the interposition of sliding seals ( 34 . 34 ' ), which are preferably adjustable, on the outer circumference of the shell ( 20 ) issue. Dryer according to one of claims 6 to 10, characterized in that the at least one gas inlet ( 30 ) is assigned or connected upstream of a gas conditioning device. Dryer according to one of claims 6 to 11, characterized in that the at least one gas outlet ( 32 ) is a dust filter upstream or downstream. Dryer according to one of claims 6 to 12, characterized in that the at least one gas inlet ( 30 ) is a pressure fan upstream or upstream and / or that the at least one gas outlet ( 32 ) is a suction fan or downstream. Dryer according to one of the preceding claims, characterized in that a first end ( 21 ) of the screw conveyor ( 2 ) a to the environment substantially gas-tight sealed feed-in device ( 4 ) assigned. Dryer according to claim 14, characterized in that the input device ( 4 ) comprises a variable in its capacity vibratory conveyor or adjustable in their performance input screw as a metering device. Dryer according to one of the preceding claims, characterized in that a second end ( 22 ) of the screw conveyor ( 2 ) a substantially gas-tight sealed to the environment Gutausgabeeinrichtung ( 5 ) assigned. Dryer according to claim 16, characterized in that the material dispensing device ( 5 ) is formed with a lock, in particular a rotary valve. Dryer according to one of the preceding claims, characterized in that the screw conveyor ( 2 ) a central, frontally projecting each axis ( 23 ) or has two frontal, projecting stub axle for screw bearing. Dryer according to one of the preceding claims, characterized in that the screw conveyor ( 2 ) by means of at least one drive motor ( 24 ) is rotationally driven via a gear or Reibrad- or belt or chain transmission. Dryer according to one of claims 6 to 19, characterized in that in the conveying direction ( 25 ) of the material to be dried ( 6 ) seen the case ( 3 ) in a plurality of gas side separated housing areas ( 3.1 . 3.1 ' 3.2 ), whereby through each housing area ( 3.1 . 3.1 ' 3.2 ) a separate gas flow is feasible. Dryer according to claim 20, characterized in that in the conveying direction ( 25 ) of the material to be dried ( 6 ) seen at least a first hous area ( 3.1 . 3.1 ') forms a drying zone, which is traversed by a warm drying gas flow, and that at least a second housing portion ( 3.2 ) forms a cooling zone, which is traversed by a cool gas stream. Dryer according to one of claims 1 to 21, characterized in that the screw conveyor ( 2 ) is arranged horizontally. Dryer according to one of claims 1 to 21, characterized in that the screw conveyor ( 2 ) is arranged inclined to the horizontal, wherein preferably the angle to the horizontal is at most 45 °.