Patent Grant
8844162
This application is a national stage application of International Application No. PCT/EP2009/058977, filed on Jul. 14, 2009, which claims the benefit of European Patent Application No. 08012666.7, filed on Jul. 14, 2008, the entire contents of both applications are incorporated herein by reference.
1. Field of the Invention
Embodiments of the present invention relate to a device for removing at least fluids from a mixture of particulate materials, comprising a container having a circular process chamber with a cylindrical external contour, an input device for inputting a mixture of particulate materials into the process chamber, a discharge device for discharging the particulate materials at least partly freed at least of the fluids from the process chamber, a feed device for feeding a fluidizing agent from below into the process chamber and at least one conditioning device for conditioning, in particular heating, the fluidizing agent in the direction of flow prior to the feed device, wherein up to n walls and n cells extending in the vertical direction are provided in the process chamber, where nεN, a first cell is in operative connection with the input device, an nth cell is in operative connection with the discharge device, the upper ends of the n cells are open, the first (n−1) cells are adapted to allow the fluidizing agent to flow therethrough from below through a base provided with first openings, and the walls between the n cells, from the first to the nth cell, each comprise at least one second opening for passage of particulate materials, as well as a method for removing at least fluids from a mixture of particulate materials in such a device.
2. Description of the Related Art
A device for removing fluids and/or solids is described, for example, in EP 07002861.8-1266, not pre-published, and will be explained in more detail below with reference to
The container 2 set up on the rack 4 comprises at its lower end facing the rack 4, a vaulted base 5 in which there is disposed a not illustrated fan impeller by which a fluidizing agent in particular, overheated vapor, is circulated in the container 2. Within the container 2, there is disposed a substantially cylindrical super heater 6, so that the fluidizing agent is introduced from below into a substantially circular process chamber 20, which is designed between the super heater 6 and the outer skin 3 and into which materials to be treated can be input by way of a not illustrated input device. Therein, the process chamber 20 is delimited at its lower end by a distribution plate 7 held by means of a distribution plate holder which allows the passage of the fluidizing agent through a plurality of not shown openings from below, but does not permit the materials to be treated to fall through.
Above the distribution plate 7, there are disposed vertically aligned walls 8, which extend from the external wall of the super heater 6 to the container wall, i.e. the outer skin, and form n cells between them. The walls 8 can reach down to the distribution plate 7 or form a free space in between. The cells formed by the walls 8 are open at the top, so that the fluidizing agent flows through the cells from the bottom up and fluidizes the materials or particles to be treated, partly carrying them along upwards and transporting them into a downstream cell, if necessary. The fluidizing agent does not substantially flow through the nth cell or discharge cell provided with a not illustrated discharge device, so that any material entering such cell without a distribution plate from the top or along the distribution plate 7, reaches the base area and can be removed from the discharge cell by way of the discharge device, for example, a conveying screw.
Above the walls 8, there follow swirl blades 9 which can also be disposed, staggered, between the walls 8 in the circumferential direction and which correspond, in their vertical extension, approximately to the vertical extension of the walls 8 or extend beyond them, i.e. can be longer than the walls. The swirl blades 9, each one at its lower side facing the walls 8, are substantially aligned parallel to the walls 8, so that the pressure side of the swirl blades 9 is oriented at an angle of 0° to the axial component of the flow velocity of the fluidizing agent. The swirl blades 9 are designed curved in the embodiment illustrated in
At their upper end, the swirl blades 9 comprise a curve of up to 35° to the axial component of the flow velocity of the fluidizing agent to divert the stream of the fluidizing agent as well as that of the materials in the circumferential direction. The swirl blades 9 constitute an extension of the walls 8, wherein such extension can be designed with or without a gap between the swirl blades 9 and the walls 8. The swirl blades 9 can form a simple or double-curved area, i.e. comprise a curve around both the axial component and a radial component in order to divert the flow of the fluidizing agent and the direction of motion of the material or the solids according to the requirements. Instead of a curve, an inclination of otherwise straight-walled swirl blades 9 can also be provided for diverting the direction of flow.
Above the swirl blades 9, there is designed a transition area 10 embodied as a free space, which is provided without internals influencing the flow, so that the flow of the fluidizing agent as well as the transport of the same, together with the particles carried along in the fluidizing agent stream, can substantially take place unhindered. Such free space 10, the so-called transition area, is designed in an annular form and allows an uninterrupted, free, circular passage of both the materials and the fluidizing agent in the horizontal plane.
Above the swirl blades 9 and the transition area 10, there are disposed additional swirl blades 11, which also comprise a simple or double-curved area on their pressure side, with an entry angle of up to 15° in relation to the axial flow velocity component. In the same nomenclature, the exit angle is up to 90°, wherein the inside diameter of the blading corresponds to the outside diameter of the super heater 6.
The additional swirl blades 11 are a component of a dust separator 12, the outside diameter of which is smaller than the outside diameter of the process chamber 20 and thus smaller than the outside diameter of the container housing in the area of the walls 8 and the swirl blades 9. The outside diameter of the additional swirl blading corresponds to the outside diameter of the dust separator 12. By adapting the additional swirl blading to the swirl blades 9, the construction of the device 1 will be optimized with regard to the pressure loss, so that the overall device can be operated at a high level of efficiency. Therein, the external contour 3 of the container 2 is cylindrical at least up to the level of the swirl blades, in the present case up to the level of the dust separator 12 or the additional swirl blades 11, which avoids a material-intensive design of the container 2, preferably designed as a pressure container. The swirl blading generates and supports a pre-swirl or the swirl flow above a fluidized bed present in the chamber 20, which ensures that the required and desired further transport from the input cell to the discharge cell is not only supported for fine particles. Within the dust separator 12, there is generated a centrifugal field in which the dust particles and particulate materials carried along are moved around externally and are discharged through an opening.
Above the additional swirl blades 11, there are disposed return blades 13, oriented opposite the swirl direction, which redirect the swirl of the fluidizing agent, transforming it into a static pressure to feed the fluidizing agent into the super heater 6. The return or back-swirl blades 13 also comprise a simple or double-curved or inclined area with an entry angle of up to 90° in relation to the axial flow velocity component of the fluidizing agents, wherein the exit angle is up to 10° in the same nomenclature. The inside diameter of the blading corresponds to the outside diameter of an outlet pipe 14, while the outside diameter of the blading corresponds to the inside diameter of the super heater 6. By way of the upper opening 14a as shown in
Furthermore, EP 0 955 511 B1 describes an alternative device for drying granular material by means of overheated vapor in which an arrangement for automatically regulating a particle flow from cell to cell, preferably comprising a shutter for an opening of a wall between two adjacent cells, is provided between all processing cells, including an input cell and a discharge cell. However, the use of such shutters involves the risk that an accumulation of granular material occurs before each closed shutter, so that the respective shutter gets jammed and can thus no longer be opened purposefully, with the consequence that neither the degree of drying nor the discharge quantity of dried granular material can be adjusted reproducibly.
Therefore, an object of embodiments of the present invention is to further develop the device of the above-mentioned type in such way that it overcomes the disadvantages of the prior art.
This object is achieved according to the embodiments of the present invention by attaching at least one boundary wall for delimiting an intermediate space between the (n−1)th cell and the nth cell to the wall between the (n−1)th cell and the nth cell, wherein the intermediate space is connected to the (n−1)th cell by way of the second opening in the wall between the (n−1)th cell and the nth cell, which, in particular, is designed in the form of a recess at the side of said wall facing the base, the intermediate space can be connected to the nth cell by way of at least a third opening, which, in particular, is designed in the form of a recess in the boundary wall at the side of the boundary wall facing the base, the intermediate space can be closed by the boundary wall at the upper end thereof opposite the base and to the side, and fluidizing agent can flow from below through first openings in the base, and the third opening can be closed or opened at least temporarily, at least partly by at least one closing member of the discharge device.
Therein, it can be provided that the closing member can be moved, preferably controlled, in particular depending on output data of at least one sensor, by way of a driving device of the discharge device.
Therein, it is preferred that a fluidized bed of the particulate material can be generated by the fluidizing agent in the first (n−1) cells and the intermediate space, and the sensor measures at least one characteristic quantity of the fluidized bed, wherein preferably no fluidized bed is present in the nth cell.
Therein, it is proposed by the invention that a differential pressure of the fluidized bed can be measured by way of the sensor, preferably, by means of a first detector within the fluidized bed and a second detector outside, in particular, above the fluidized bed, in particular in the (n−1)th cell.
Furthermore, it can be provided that the driving device comprises at least one motor, such as a geared motor or a stepper motor, preferably with a positioner for positioning the closing member, and/or the closing member is connected to a motor of the driving device by way of a shaft.
Therein, it is proposed that the closing member comprises a circular segment cross-section disposed coaxially to the shaft.
Moreover, preferred embodiments according to the invention are characterized in that at least two closing members are provided, wherein preferably the closing members are disposed and evenly distributed on a concentric circle around the shaft.
It is also proposed by the embodiments of the present invention that each closing member can be moved from the bottom up along the third opening, preferably, on a circular arc.
Furthermore, it can be provided that each closing member is disposed in the nth cell and the associated driving device is disposed outside the container, so that the shaft between the driving device and the closing member passes through the external contour of the container.
It can also be provided that the boundary wall, in particular a roof part of the same, extends at the upper end of the intermediate space from the third opening to the second opening in the wall between the (n−1)th cell and the nth cell, preferably inclined and/or bent upwards.
Moreover, it is proposed that the discharge device comprises a conveying device, which runs at least partly in the nth cell.
It can also be provided that the discharge device comprises a variable-frequency inverter.
Furthermore, embodiments of the invention can be characterized in that at least a fourth opening is disposed above the second opening in the wall between the (n−1)th cell and the nth cell, so that particulate material can enter from the (n−1)th cell into the nth cell above the intermediate space.
Therein, it is proposed that the fourth opening can be at least partially and temporarily closed, preferably by a further closing member of the discharge device.
Furthermore, preferred embodiments of the present invention are characterized by a wall between the nth cell and the first cell, wherein such wall comprises no opening.
It can also be provided that the n cells are disposed concentrically around the conditioning device preferably comprising a super heater.
Moreover, it is proposed that swirl blades, which are inclined or curved in the direction of flow of the particulate materials from the first cell to the nth cell are disposed above the walls, wherein the outside diameter of the swirl blades is not greater than the outside diameter of the walls and the swirl blades are surrounded by an external cover, which does not project radially beyond the external cover which surrounds the walls.
Embodiments of the present invention also provide a method for removing at least fluids from a mixture of particulate materials in a device according to the embodiments of the present invention are characterized in that the residence time of the particulate material in the process chamber of the device is determined depending on a fluidized bed differential pressure in the process chamber.
Therein, it can be provided that, for discharging the particulate materials at least partly freed at least of fluids from the process chamber, each closing member closing the third opening is at first turned from its respective closing position into an opening position preferably completely releasing the third position, preferably gliding past the third opening from the bottom up, and the closing member is subsequently held in the opening position for a first certain duration.
Alternatively, it is proposed that, for discharging the particulate materials at least partly freed at least of fluids from the process chamber, each closing member is at first brought into a stationary state for a second certain duration, in which state the third opening is partly opened, and the third opening is further opened, in particular completely opened, at least once for a third certain duration during the second certain duration, wherein, preferably for opening the third opening at least in some areas, at least one closing member is moved past the third opening from the bottom up.
Moreover, it can be provided that, for at least partly closing the third opening, preferably, depending on the first or second and/or third duration, at least one closing member first closes the third opening either from the top down or from the bottom up.
Finally, it is also proposed according to the embodiments of the present invention that the process chamber is filled with a mixture of particulate materials and a fluidizing agent is fed into the process chamber in such way that the fluidized bed builds up at least in the (n−1)th cell, at least up to the fourth opening.
Thus, embodiments of the present invention are based on the surprising finding that, when operating the drying device with a continuous input of particulate materials to be dried and a continuous discharge of dried material, a fluidized bed differential pressure gradient is induced, which is sufficient as a driving force for transport of the particulate materials to be dried in the fluidized bed from processing cell to processing cell, on the one hand, and ensures a permanent particle movement before a closing member, on the other hand, which is only necessary between the last processing cell, which spreads the fluidized bed, and the discharge cell without a fluidized bed, if the closing member is not used for closing an opening of a wall between said last processing cell with a fluidized bed and the discharge cell without a fluidized bed, but for closing an opening of an intermediate space between said last processing cell and the discharge cell, so that no jamming of particles and/or no accumulation of a product difficult to fluidize will occur before the closing member.
Furthermore, based on the knowledge obtained from the embodiments of the present invention, when the quantity of particulate materials fed into the fluidized bed is increased, the fluidized bed differential pressure will increase so that, for guaranteeing stationary process conditions in the fluidized bed with an approximately constant filling and product residence time, an adjustment of the discharge of the particulate materials at least partly freed at least of fluids has to be made depending on said fluidized bed differential pressure. This enables a controlled quantity of particulate materials in the fluidized bed, with a simultaneous optimization of the removal of the fluids from the particulate material. Furthermore, it is ensured that the fluidized bed in the process chamber will not become depleted of fluidized material and is thus maintained even in case of a short-time interruption or reduction of the feeding of said mixture of particulate materials into the process chamber.
Further features and advantages of the embodiments of the present invention will be apparent from the following description in which exemplary embodiments of the invention are explained in more detail based on the accompanying drawings described below.
a to 5c show local sectional views of a processing cell and a discharge cell of the device of
A drying device according to the embodiments of the present invention constitutes a further development of the device 1 as described with reference to
According to
As can be seen from
The opening 19a of the loosening space 19 can be closed by way of one of the closing members 42a, 42b, as illustrated, for example, in
The mode of operation of the drying device 1 is hereinafter explained with reference to
If a mixture of particulate materials is constantly introduced into the process chamber 20, more precisely into the input cell 15 in the process chamber 20, and a fluidizing agent, for example, in the form of vapor heated up in the super heater 6 and blown by way of the fan impeller in the base 5 through openings in the distribution plate 7 from the bottom up, is simultaneously introduced into the process chamber 20, then a fluidized bed is built up in the process chamber 20 and with it, a fluidized bed differential pressure. Such fluidized bed differential pressure is proportional to the quantity of particulate materials in the fluidized bed. The driving force for the materials transport from the input cell 15 to the discharge cell 17 consists in a permanent fluidized bed differential pressure difference, which adjusts from the input towards the discharge in case of a continuous operation of the drying device 1. Therein, the materials transport goes from the input cell 15 via the processing cells 16 into the discharge cell 17, and through openings in the intermediate walls 8, such as, for example, the opening 8b in the intermediate wall 8a between the last processing cell 16 with a distribution plate 7 and the discharge cell 17 without a distribution plate 7. In order to guarantee stationary process conditions in the fluidized bed, with an approximately constant filling and product residence time, materials must be able to flow out according to the inflow of the materials from the fluidized bed, i.e., must be able to leave the drying device 1 through the opening 17a. This can occur in different ways.
Before the flowing out of materials is described in more detail, it should be mentioned that, in case of a closure of the opening 19a of the loosening space 19 by the closing member 42a, as shown in
First Variant
The closing member 42a is turned or rotated clockwise from the closing position as shown in
The complete unobstruction of the opening 19a as shown in
After a fixed opening time, the closing member 42b is then brought back in its closing position and will remain there for a fixed duration. Therein, the speed of the rotary movement must be so high that the fluidized bed before the discharge cell 17 will not be depleted of solids through too long an opening time of the loosening space 19. Therein, a speed of 10 to 20 revolutions per minute is desirable.
On the shaft 41, several closing members can be disposed to influence the opening times.
If the product stream from the processing cell 16 into the discharge cell 17 becomes too large, one of the closing members 42a, 42b can be turned into an only partly opened position, see
The duration of both the closed and the opened state of the loosening space 19 is to be controlled depending on a fluidized bed differential pressure. The latter is measured by way of two pressure sensors 44a, 44b, wherein the one pressure sensor 44a is disposed above the fluidized bed, and the other pressure sensor 44b is disposed within the fluidized bed in direct proximity above the distribution plate 7 of the processing cell 16, as can be seen in
The closing members 42a and 42b are selectively moved into their individual positions by way of the driving device 43, which can comprise a geared motor with a positioner.
For facilitating the discharge of the particulate material from the discharge cell 17, the conveying device 30 can be used.
Second Variant
The closing member 42a can be in a partly opened position, as shown in
For avoiding obstructions of the loosening space 19 by coarse particles, the closing member 42a can completely unobstruct the opening 19a in a preset rhythm for a short duration, as shown in
If, in the rotary movement of the closing member 42a for closing the opening 19a, a torque which exceeds a preset maximum value during a clockwise rotation should occur, the rotation can also take place anticlockwise. Moreover, this measure serves to remove any particles that may be jammed between the closing member 42a and the borders of the opening 19a of the loosening space 19.
The necessary rotary movement of the closing members 42a, 42b also depends on the number of the closing members.
Third Variant
Through a further opening 8c in the wall 8a between the processing cell 16 and the discharge cell 17, which is visible in
If the opening 8c is disposed in the area of the nominal fluidized bed level, it functions as a stationary weir that allows particulate materials to enter from the processing cell 16 into the discharge cell 17.
If one combines a particle transport by way of the opening 8c with a transport through the loosening space 19, either according to the first variant or according to the second variant, then substantially coarse particulate materials will flow through the loosening space 19, which helps to improve a controlled fluidization.
The features disclosed in the above description, in the drawings, and in the claims can be essential to the realization of the invention in its different embodiments, both individually and in any combination.
| Number | Date | Country | Kind |
|---|---|---|---|
| 08012666 | Jul 2008 | EP | regional |
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/EP2009/058977 | 7/14/2009 | WO | 00 | 3/15/2011 |
| Publishing Document | Publishing Date | Country | Kind |
|---|---|---|---|
| WO2010/007057 | 1/21/2010 | WO | A |
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| Entry |
|---|
| International Search Report mailed Sep. 25, 2009 for International Application No. PCT/EP2009/058977. |
| Number | Date | Country | |
|---|---|---|---|
| 20110162229 A1 | Jul 2011 | US |
