JP2002316036A - Slurry supplying mechanism of spray drier - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain such a slurry supplying mechanism of a spray drier that the particle size of the granulated powder is made uniform and the yield is enhanced by making the pulsating pressure of a roller type tube pump smooth to restrain the amount of slurry to be supplied to the spray drier from being fluctuated. SOLUTION: Two branched tubes 12a, 12b different in length are connected to the respective middles of liquid supplying tubes 11, 13 connecting the roller type tube pump 5 and a spray part of the spray drier.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a disk type spray dryer, and more particularly to a slurry supply mechanism for a spray dryer using a roller tube pump.

[0002]

2. Description of the Related Art In general, in a disk type spray dryer, slurry is supplied to a spray section at a low cost, the slurry type is easily exchanged, and there is little contamination such as metal. A roller tube pump is used.

[0003] Even if the roller-type tube pump is rotating at a constant speed, the pulsating pressure caused by the roller makes the supply amount of slurry to the spraying part inconsistent and the particle size of the obtained granulated powder becomes large (particle size). Distribution becomes wider). Also,
When a large amount of slurry is supplied to the spray part at once at the peak of the pulsating pressure, the slurry turns into droplets and adheres to the wall surface of the collection tank, and remains undried, which reduces the yield of granulated powder. I do.

[0004]

SUMMARY OF THE INVENTION In view of the above problems, it is an object of the present invention to smooth the pulsating pressure of a roller type tube pump, suppress fluctuations in a slurry supply amount, make the particle size of granulated powder uniform, and An object of the present invention is to provide a slurry supply mechanism for a spray dryer, which increases the yield.

[0005]

In order to solve the above-mentioned problems, according to the structure of the present invention, two branch tubes having different lengths are connected in the middle of a liquid sending tube connecting a roller type tube pump and a spray section. It is characterized by the following.

Further, according to the structure of the present invention, a plurality of support plates supported on the same rotary shaft with a rotation phase shifted from each other are provided on a roller tube pump, and the plurality of rollers supported by the support plates have the same diameter and the same length. The plurality of branch tubes are passed through the plurality of branch tubes, and the plurality of branch tubes are combined into one liquid sending tube and connected to a spray unit.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In the present invention, a bifurcated (or plural) branching tube is connected in the middle of a liquid feeding tube connecting a roller type tube pump and a spray unit. The pipe diameter of each branch tube is 1 / √2 (error range ± 10%) of the pipe diameter of the liquid sending tube upstream of the branch section. By making one of the branch tubes a length that is half the interval between the peaks of the pulsating pressure, the height of the peak of the pulsating pressure is halved, and the peaks of the pulsating pressure are the same in opposite phase. A pulsating pressure of pressure occurs. Accordingly, the pulsating pressure of the roller tube pump is smoothed, the amount of slurry supplied becomes almost constant, the particle size distribution of the granulated powder is narrowed (uniform), and the yield is improved.

In addition, a plurality of rollers having the same rotation axis and a rotational phase shifted from each other are disposed in the tube pump, a plurality of branch tubes having the same diameter and the same length are passed through the plurality of rollers, and the plurality of branch tubes are fed by one. The liquid tubes may be collectively connected to the spray unit.

When a material powder of a sintered body is prepared using a spray dryer equipped with a slurry supply mechanism according to the present invention, a homogeneous sintered body having excellent mechanical properties can be obtained.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS As shown in FIG. 1, a spray type spray dryer 20 has a rotary shaft 14 projecting into the recovery tank 17 supported by an inlet 15 provided on the upper end wall of the recovery tank 17. The slurry is supplied onto a disk 16 which is connected substantially horizontally with the disk 16 and receives the centrifugal force by the disk 16 so that the slurry is scattered in a radial direction. Hot air is sent from the blower tube 18 to the collection tank 17 by a blower. Therefore, when the slurry is blown off the disk 16, it is dried and formed into fine particles, which accumulates at the bottom of the recovery tank 17, and is taken out from the outlet 19 as needed.

The slurry supply mechanism is provided between a pair of circular support plates 8 (in the case of cantilever support, only one support plate 8) is connected to the rotating shaft 7 at an axial interval. A plurality of rollers 9 are supported at equal intervals in the direction, and a liquid supply tube 10 made of an elastic material disposed between the rollers 9 and the flat plate 6 (which may be curved in an arc shape) is crushed to form a slurry. Are sequentially sent to the liquid sending tube 11, and the slurry 2 in the storage tank 3 is sucked into the liquid sending tube 10 via the liquid sending tube 4 by the vacuum pressure when the liquid sending tube 10 is restored to a circular cross section.

As shown in FIGS. 1 and 2, according to the present invention,
In the middle of the liquid supply tubes 11 and 13 connecting the roller type tube pump 5 and the spray unit, a buffer unit 12 is formed by connecting two branch tubes 12a and 12b having different lengths. The pipe diameter of each branch tube 12a, 12b is set to 1 / √2 (error range ± 10%) of the pipe diameter of the liquid feed tube 11 upstream of the branch part. When the distance from the rotation center of the tube pump 5 to the rollers is R and the number of rollers is N, the difference between the lengths of the two branch tubes 12a and 12b is π.
It is assumed to be an integral multiple of R / N. The slurry of the liquid sending tube 11 forms a pulsating flow, and the branch tubes 12a, 12 each having a half passage area.
2b, and the pulsating flow of the slurry of the branch tube 12b is
The fluid flows into the liquid sending tube 13 with a delay of half a pitch of the pulsating flow of the slurry of the branch tube 12a. Accordingly, the pulsation pressure of the slurry of the liquid sending tube 13 is reduced by half, and
As a result, the flow of the slurry in the liquid feeding tube 13 is smoothed.

In the embodiment shown in FIGS. 3 and 4, just before the tube pump 5, the liquid sending tube 10 is connected to a branch tube 10a.
And a branch tube 10 b, and merges into one liquid sending tube 11 at the outlet side of the tube pump 5. The tube diameter of each branch tube 10a, 10b is 1 / √2 of the tube diameter of the liquid feed tube 4 upstream of the branch portion (error range ± 10%).
And A plurality of (four) tube pumps 5 are provided between a pair of support plates 8a and a pair of support plates 8a connected to a common rotary shaft 7.
The rollers 9a are supported at equal intervals in the circumferential direction, so that the rollers 9a crush the branch tube 10a with the flat plate 6 (see FIG. 2). Similarly, a plurality of (four) rollers 9 b are supported between the support plate 8 a and the support plate 8 b, and the rollers 9 b crush the branch tube 10 b between the support plate 8 a and the flat plate 6.

As shown in FIG. 3, the rollers 9a and 9
b and the supporting plates 8a and 8b shifted by a half pitch in the circumferential direction.
And the supporting plates 8b and 8c. Therefore, as shown in FIG. 5, the tube pump 5 according to the present invention has a smaller amount of slurry to be repelled than a conventional tube pump in which a single tube is disposed between a rotating roller and a flat plate. The peak of the pulsation pressure becomes smaller, and eventually the spray dryer 20
The amount of slurry supplied to the disk 16 is smoothed, so that excessive slurry is not supplied to the disk 16 temporarily, so that the granulated powder has a uniform particle size and the yield is improved.

[Specific Embodiment 1] A roller type screw according to the present invention.
Alumina Al
_TwoO_Three Slurry (solid content 50%) under the following conditions
To the spray dryer and granulate for 1 hour.
Pulsating pressure of the slurry sent to the
The rate was measured.

Granulation conditions: Disk rotation speed 1000 rpm Liquid sending speed 5.5 lt./hr Inlet temperature 10 ° C. Blasting temperature 85 ° C. Binder used PVA (1 wt.% In powder amount) The same measurement was performed when a slurry supply mechanism was used.

[Specific Example 2] Under the same method and conditions as in Example 1, the slurry supply mechanism and the disk type spray dryer according to the present invention were used to form silicon nitride Si ₃ N ₄ , yttria Y ₂ O ₃ and alumina. Granulated powder was prepared from a slurry in which Al ₂ O ₃ was mixed at a ratio of approximately 90: 5: 5. Using the obtained granulated powder without classification, a required molded body was prepared. After the molded body was degreased, it was fired in a nitrogen atmosphere at a temperature of 1850 ° C. for 6 hours. A test piece was cut out from the obtained fired body, and the four-point bending strength was measured.

In the case where the slurry supply mechanism of the conventional spray dryer is used, a required molded body is formed from the obtained granulated powder, and after the molded body is degreased, it is heated in a nitrogen atmosphere at a temperature of 1850 ° C. It was baked for 6 hours. A test piece was cut out from the obtained fired body, and the four-point bending strength was measured.
While the four-point bending strength of the test piece obtained from the granulated powder using the conventional slurry supply mechanism was 850 MPa, the four-point bending of the test piece obtained from the granulated powder using the slurry supply mechanism of the present invention was used. The strength was 1021 MPa.

[Specific Example 3] Under the same method and conditions as in Example 1, the slurry (a solid content of 50%) of alumina Al ₂ O _{3 was formed} by the slurry supply mechanism and the disk type spray dryer according to the present invention. A granulated powder was prepared. The pulsating pressure of the slurry sent to the desk, the particle size distribution of the granulated powder, and the yield were measured.

Similar measurements were also made when a conventional spray dryer slurry supply mechanism was used.

According to the slurry supply mechanism of the spray dryer according to the present invention, the width of the particle size distribution of the granulated powder is narrowed, and the yield of the granulated powder using the slurry supply mechanism of the conventional spray dryer is 60%. In contrast, the yield of granulated powder using the slurry supply mechanism of the spray dryer of the present invention is 75%.
%.

[0022]

As described above, according to the present invention, two branch tubes having different lengths are connected in the middle of a liquid feeding tube connecting a roller type tube pump and a spray portion, or the same rotary shaft is used for the roller type tube pump. Arrange multiple support plates in
A plurality of branch tubes having the same diameter and the same length are passed through a plurality of rollers supported on each support plate with a rotation phase shifted, and the plurality of branch tubes are combined into one liquid feed tube and connected to a spray unit. As a result, the pulsating pressure of the roller tube pump is smoothed, and the slurry supply amount is stabilized. Accordingly, the width of the particle size distribution of the obtained granulated powder becomes narrow,
The yield is improved. That is, high-quality granulated powder can be easily obtained.

[Brief description of the drawings]

FIG. 1 is a side sectional view of a spray dryer including a slurry supply mechanism according to the present invention.

FIG. 2 is a side view showing a configuration of the slurry supply mechanism.

FIG. 3 is a side view of a slurry supply mechanism according to a second embodiment of the present invention.

FIG. 4 is a plan view of the slurry supply mechanism.

FIG. 5 is an explanatory diagram showing the operation of the slurry supply mechanism according to the present invention and a conventional slurry supply mechanism in comparison with the particle size distribution of granulated powder obtained by a spray dryer.

[Explanation of symbols]

2: Slurry 3: Storage tank 4: Liquid sending tube 5: Roller type tube pump 6: Flat plate 7: Rotating shaft 8, 8a,
8b: Support plate 9, 9a, 9b: Roller 10: Liquid feed tube 10a, 10b: Branch tube 11: Liquid feed tube 12: Buffer 12a, 12b: Branch tube 13: Liquid feed tube 14: Rotating shaft 15: Inlet 1
6: Disk 17: Recovery tank 18: Blast tube 19: Outlet 20: Spray dryer

Claims (4)

[Claims] 1. A slurry supply mechanism for a spray dryer, characterized in that two branch tubes having different lengths are connected in the middle of a liquid sending tube connecting a roller type tube pump and a spray section. 2. The slurry supply mechanism for a spray dryer according to claim 1, wherein each flow passage cross-sectional area of the branch tube is 1 / √2 (± 10%) of a flow passage cross-sectional area of the liquid sending tube. 3. When the distance from the rotation center of the tube pump to the rollers is R, and the number of rollers is N,
The slurry supply mechanism for a spray dryer according to claim 1, wherein the difference between the lengths of the two branch tubes is an integral multiple of πR / N. 4. A roller tube pump having a plurality of supporting plates supported on the same rotating shaft with a rotational phase shifted from each other, and a plurality of branch tubes having the same diameter and the same length are provided on the plurality of rollers supported by the supporting plate. Wherein the plurality of branch tubes are combined into a single liquid feed tube and connected to a spray unit.