The present invention relates to an apparatus for heating or cooling a raw material while being stirred and conveyed using a mechanism with two shafts that rotate at unequal speeds.
Conventionally, a kneading apparatus is known in which two shafts each having a plurality of paddles (blades) erected so as to be arranged helically with an inverse helix to each other are caused to rotate at unequal speeds to knead and convey a raw material in one direction (blow-described Patent Document 1). In such a kneading apparatus, both the rotary shafts are caused to rotate at unequal speeds and the distal end of the paddle sequentially approaches the external peripheral surface of the facing rotary shaft with its phase changing, so that the kneaded object that has adhered to the external peripheral surface of the facing rotary shaft is effectively scraped off, thus performing self-cleaning.
A drying apparatus is also known in which such two rotary shafts that rotate at unequal speeds are provided with a plurality of fan-shaped disks to stir, convey and dry an object such as sludge (blow-described Patent Document 2). In such a kind of drying apparatus, the two rotary shafts and the disks mounted to each rotary shaft are all made hollow and the inside space of each rotary shaft communicates with the inside spaces of the disks, respectively.
Steam is supplied to the inside space of each rotary shaft from one end thereof, and the supplied steam flows from the inside space of the rotary shaft through the inside space of each disk mounted to the rotary shaft to heat the rotary shaft and the surface of the disk. The object to be dried approaches or contacts the disk surface or the surface of the rotary shaft in the process of being stirred and conveyed, so that the object to be dried is heated and dried with its percentage of moisture content reduced. Steam loses heat by that amount and undergoes condensation to drainage.
Patent Document 1: WO 2009/044608
Patent Document 2: JP 2014-131784
An object to be dried may have high adhesion depending upon the percentage of moisture content before or after drying when it passes through a given percentage range of moisture content during drying. In the arrangements in Patent Documents 1 and 2, even an object that can be scraped off by the self-cleaning effect due to the unequal rotation of the rotary shafts may have strong adhesion as the drying progresses. This causes the scraping effect to be remarkably deteriorated.
Particularly, in the drying apparatus as disclosed in Patent Document 2, the disk is mounted substantially upright on the rotary shaft and the scraping effect for the disks is originally low, so that the adhesion of the object to be dried progresses gradually. There is thus a problem that the drying efficiency decreases.
As described above, the raw material not only needs heating, but also requires cooling. Also in such a case, the raw material adheres to the disk, and the cooling efficiency for the raw material disadvantageously deteriorates.
The present invention is made in view of such problems and an object thereof is to provide an apparatus for heating or cooling a raw material being capable of increasing the scraping effect for a raw material such as an object to be dried or cooled and being capable of improving the heating or cooling efficiency.
The present invention concerns an apparatus for heating or cooling a raw material in which a disk mounted on a rotary shaft is heated or cooled and the raw material is brought into contact with the disk surface, comprising:
first and second rotary shafts that are disposed in a facing manner;
a plurality of disks that are provided upright at intervals on the first rotary shaft;
a plurality of disks that are provided upright on the second rotary shaft so as to be shifted a predetermined distance from the disks of the first rotary shaft, respectively;
wherein a scraper member that enters between the surfaces of the facing adjacent disks to scrape the raw material is fixed to each disk of the first and second rotary shafts; and
the first and second rotary shafts are rotated at unequal speeds such that the scraper member approaches the facing disk surface with a trajectory drawn thereon varying.
In the present invention, scraper members for scraping a raw material are fixed to two rotary shafts, which are caused to rotate at unequal speeds. Since the scraper members approach the facing disk surfaces with the trajectories drawn thereon varying, the raw material that has adhered to the disk surfaces is effectively scraped off. This scraping effect improves the heating or cooling efficiency for the raw material.
In the following, the present apparatus of the invention will be described in detail based on embodiments shown in drawings.
In
At the top of the right end shown in
The raw material supplied from the raw-material supply opening 30 is heated or cooled while being stirred, as will be described below, and is discharged from a raw-material discharge opening 31 at the left end shown in
Inside the housing 1, two rotary shafts 3 and 4 of the same cross-sectional shape are provided in parallel to each other in the longitudinal direction. The rotary shafts 3 and 4 are made of metal such as stainless steel and has a cylindrical shape, having inside thereof hollow portions 3a, 4a of a circular cross section (
The rotary shafts 3 and 4 have their right ends inserted into a gear box 12. Gears 13 and 14 that mesh with each other are fixed to the rotary shafts 3 and 4 inside the gear box 12.
A sprocket 15 is fixed to the outside of the bearing 5 of the rotary shaft 3. Mounted on a base 20 fixed to the struts 11 is a motor 18 whose output shaft is reduced in speed by reduction gears 19. A sprocket 17 is fixed to the output shaft of the reduction gears 19. A chain 16 is stretched between the sprockets 15 and 17.
A unidirectional rotational drive force from the motor 18 is transmitted to the rotary shaft 3 via the sprocket 17, the chain 16 and the sprocket 15, causing the rotary shaft 3 as a drive shaft (a first rotary shaft) to rotate in one direction, and the rotational drive force is also transmitted to the rotary shaft 4 via the gears 14 and 13, causing the rotary shaft 4 as a driven shaft (a second rotary shaft) to rotate in the opposite direction. The rotary shafts 3 and 4 are caused to rotate via the gears 13 and 14 at unequal speeds with a rotational speed ratio of N:K, wherein N and K are a natural number. For example, N is set to 16 and K to 15 in the present embodiment, and the rotary shafts 3 and 4 are caused to rotate with a rotational speed ratio of 16:15. The rotating directions of the rotary shafts 3 and 4 are such that the shafts rotate inward towards each other when viewed from above, as seen in
Metallic disks 40 as stirring members are mounted on the external periphery of the rotary shaft 3 at equal intervals d1 at a positon Pn (n=1 through 14).
As shown in
Fixed to the outer peripheral end of the disk blade 41 is a metallic mount plate 43 to which a rod- or plate-shaped scraper members 45, 45′ (hereinafter referred to as pins) are fixed in screw type in the direction perpendicular to the mount surface 43 in the forward and backward direction (in the direction along which the rotary shaft 3 extends). As shown in an enlarged view in the upper right of
Similarly, metallic disks 50 as stirring members are mounted on the external periphery of the rotary shaft 4 at a positon Qn (n=1 through 14) at the same equal intervals d1 as those of the disks 40. The disk 50 also has a pair of fan-shaped disk blades 51, 51′ that are the same in shape as the disk blades 41, 41′, and the disk blades 51, 51′ are fixed above and below the rotary shaft 4 perpendicularly thereto. The disk 50 also looks as a whole like a disk that is disposed vertically upright on the rotary shaft 4 concentrically with the axis center 4b thereof. Therefore, the disk 50 is also simply shown as a circle in the following description in connection with
Pins 55, 55′ that are similar to the pins 45, 45′ are fixed in a similar manner to a metallic mount plate 53 on the outer peripheral end of the disk blade 51. As shown in an enlarged view in the upper right of
As shown in
As shown in
On the other hand, in a case where the raw material needs cooling, cooling water is supplied from the medium supply opening 32. The cooling water is supplied from the hollow portion 3a of the rotary shaft 3 through the inner pipes of the double pipes 46, 46′ to the hollow portions 41a, 41a′ of the disk blades 41, 41′ to cool the disk blades 41, 41′ from the inside. The cooling water inside the disk blades 41, 41′ is returned to the hollow portion 3a of the rotary shaft 3 through the outer pipes of the double pipes 46, 46′ and discharged from the medium discharge pipe 34 through the pipe 36.
Although not shown, the insides of the disk blades 51, 51′ also form hollow portions similarly to the disk blades 41, 41′. Double pipes that protrude into the hollow portion 4a of the rotary shaft 4 are inserted into these hollow portions. Steam or cooling water supplied from the medium supply opening 33 is supplied from the hollow portion 4a of the rotary shaft 4 through the inner pipes of the double pipes to the hollow portions of the disk blades 51, 51′, and is returned to the hollow portion 4a of the rotary shaft 4 through the outer pipes of the double pipes for discharge from a medium discharge pipe 35.
Next, the operation of the apparatus thus configured will be described based on an example in which a raw material is heated and dried.
When the motor 18 is driven, a rotational drive force is transmitted to the rotary shaft 3 via the sprocket 17, the chain 16 and the sprocket 15, causing the rotary shaft 3 to rotate in one direction. The rotational drive force is also transmitted to the rotary shaft 4 via the gears 14 and 13, causing the rotary shaft 4 to rotate in the opposite direction with a rotational speed ratio of 16:15 relative to the rotary shaft 3.
When the raw material is supplied from the supply opening 31 and steam is supplied from the medium supply openings 32, 33, the steam is supplied and caused to flow from the hollow portions 3a, 4a of the rotary shafts 3, 4 through the inner pipes of the double pipes to the hollow portions of the disk blades 41, 41′ and 51, 51′. The steam inside the hollow portions 3a, 4a of the rotary shafts 3, 4 and the steam that flows through the hollow portions of the disk blades 41, 41′ and 51, 51′ heat the surfaces of the rotary shafts 3, 4 and the disks 40, 50. The raw material approaches or contacts the disk surface or the surface of the rotary shaft in the process of stirring and conveying, so that the raw material is heated as it advances toward the discharge opening 31. The steam loses heat by that amount and flows as condensed water at the bottom of the rotary shafts 3, 4 for discharge from the medium discharge openings 34, 35.
In the process of drying the raw material, the moisture content decreases depending on the raw material as the drying progresses, and the raw material strongly adheres to the surfaces of the rotary shafts 3, 4 or the disks 40, 50, in some cases causing troubles in rotation with the result that the apparatus malfunctions.
In the present embodiment, the pins provided perpendicularly on the disk surfaces enter between the facing disks as the rotary shafts rotate, and approach the disk surfaces with the phases (trajectories) being varied, allowing the raw material that has strongly adhered to be effectively scraped off. In the following, the scraping effect will be described using
As is seen from the drawing, the pin 55 of the disk 50 moves close to the surface of the disk 40 along the trajectory L1 to scrape the raw material that has adhered to the disk surface. When the disk 40 next makes one revolution, the pin 55 of the disk 50 moves close to the surface of the disk 40 along a trajectory L2 different from the trajectory L1 in
As is seen from the drawing, the pin 45 of the disk 40 moves close to the surface of the disk 50 along the trajectory M1 to scrape the raw material that has adhered to the disk surface. When the disk 50 next makes one revolution, the pin 45 of the disk 40 moves close to the surface of the disk 50 along a trajectory M2 different from the trajectory M1 in
When the rotary shafts has the same speed, the trajectory that the pin draws on the other disk surface is always the same and has no phase difference. When, however, the rotary shafts 3, 4 are caused to rotate at unequal speeds with a speed ratio of 16:15 as in this embodiment, the trajectory that the pin of one rotary shaft draws on the other disk surface has a slight deviation for every rotation of 16 or 15 cycles of rotation, as described above. This produces a dense pattern as shown in
The speed ratio is not limited to the speed ratio of 16:15 as described above, and it is possible to rotate the rotary shafts 3, 4 with a speed ratio of N:K with N and K as natural numbers. For example, the speed ratio of the rotary shafts may be 5:4 as shown in
The pin is attached at a position radially away from the center of the disk, preferably at the outer peripheral position of the disk. The pin is brought closer to the facing rotary shaft by attaching it to the outer peripheral position of the disk in this manner, so that the raw material adhered to the rotary shaft can also be effectively scraped off. Although the pin 45 of the disk 40 and the pin 55 of the disk 50 are configured so as not to collide with each other as shown in
In the embodiment describe above, the raw material needs heating. In a case the raw material needs cooling, cooling water is supplied from the medium supply openings 32, 33. The cooling water is supplied and caused to flow from the hollow portions 3a, 4a of the rotary shafts 3, 4 through the inner pipes of the double pipes to the hollow portions of the disk blades 41, 41′ and 51, 51′. The raw material approaches or contacts the disk surface or the surface of the rotary shaft in the process of stirring and conveying, so that the raw material is cooled as it advances toward the discharge opening 31. On the other hand, the cooling water is discharged from the medium discharge openings 34, 35.
In the above-described embodiment, the disk blades 41, 41′, 51, 51′ are made hollow, and the medium such as steam or cooling water is supplied to the hollow portions of the disk blades to heat or cool the raw material via the surfaces thereof. However, the disk blades 41, 41′, 51, 51′ do not necessarily have to be made hollow, and may not be hollow, especially when cooling the raw material. In the case where the disk blades are not made hollow, double pipes that are inserted into the hollow portions are also unnecessary. The steam or cooling water is supplied from the medium supply opening to the respective hollow portion of the rotary shaft and discharged from the medium discharge opening to heat or cool the raw material in this process.
In the process of cooling the raw material, the raw material may adhere strongly to the surfaces of the rotary shafts 3, 4 or the disks 40, 50 in some cases depending on the raw material. Also in such cases, the scraper members approach the facing disk surfaces with the trajectories drawn thereon varying, thereby increasing the effect of scraping the raw material for improvement in cooling efficiency even when the raw material needs cooling as in the case where it needs heating.
Number | Date | Country | Kind |
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2015-149255 | Jul 2015 | JP | national |
Filing Document | Filing Date | Country | Kind |
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PCT/JP2016/065291 | 5/24/2016 | WO | 00 |