JPH10263439A - Multicyclone - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent decrease of the flow rate in upper parts in cyclone inlet pipes by widening the diameter of an introducing pipe wider on upstream side than that in the pipe terminal from which the cyclone inlet pipes are branched and making the upper faces of the inlet parts of the cyclone inlet pipes be inclined faces as to taper the inlet pipes toward cyclones. SOLUTION: This multicyclone is provided with one introducing pipe 1 to introduce a power dust gas vertically downward, a plurality of cyclone inlet pipes 2 branched radiately from the pipe terminal of the introducing pipe 1, and cyclones 3 connected with the cyclone inlet pipes 2, respectively, in the same number as that of the cyclone inlet pipes 2. The powder dust gas flowing through the introducing pipe 1 is introduced into the cyclones 3 through the cyclone inlet pipes 2 and the powder dust is separated by centrifugal separation in the cyclones 3. The diameter of the introducing pie 1 is widened more on the upstream side to the pipe terminal from which the cyclone inlet pies 2 are branched. The upper faces of the inlet parts of the cyclone inlet pies 2 are made to be inclined faces as to taper the cyclone inlet pipes 2 toward the cyclones 3.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a solid removing device for separating and removing solid particles in a gas by centrifugal force, and more particularly to a multicyclone comprising a plurality of cyclones.

[0002]

2. Description of the Related Art Cyclones, also called centrifugal dust collectors, are widely used in the industrial field because of their simple structure and no moving parts, but the flow of gas in the cyclone is complicated. It is difficult to predict the collection rate theoretically, and it is often designed based on experience.

[0003] The gas in the cyclone normally flows as indicated by arrow A in FIG. That is, the dust gas that has flowed in from the cyclone inlet 20 descends while swirling, then reverses at a point below the cyclone, and flows out of the system from the inner cylinder 21 through the cyclone center. As the dust gas swirls and descends, the dust is centrifuged.

However, when the cyclone having the structure shown in FIG. 9 is used as it is, the outer cylinder 22 of the cyclone is used.
A secondary flow may occur in the coaxial cylindrical space between the inner cylinder 21 and the inner cylinder 21. In particular, the gas flowing from the upper part of the cyclone inlet 20 descends along the outer wall of the inner cylinder via the upper surface of the cyclone as shown by the arrow B, and is likely to be a short-circuit flow flowing out of the inner cylinder 21 as it is. The short-circuit flow causes the dust collection efficiency to decrease because the dust is carried out of the system as it is.
When the flow velocity at the upper part of the cyclone inlet 20 is significantly lower than the average flow velocity at the cyclone inlet 20, the effect of the centrifugal force decreases and the outflow of gas due to the short-circuit flow increases.

Therefore, in the conventional cyclone, the inlet piping is often designed as follows.

(1) As shown in FIG. 10, a cyclone inlet pipe is installed so as to extend in the horizontal direction through a 90 ° elbow from below vertically so that the velocity of gas flowing in the pipe becomes higher at the upper part of the pipe. To

(2) The cyclone inlet pipe itself is lengthened,
The gas flow is sufficiently developed so that the velocity distribution of the gas flowing in the pipe becomes uniform.

[0008]

However, in the case where there is an inlet pipe for guiding the dust gas vertically downward and the length of the cyclone inlet pipe cannot be sufficiently extended, the above-mentioned (1) is used. There is no way to take measure (2).

In view of these problems, an object of the present invention is to
One introduction pipe for guiding the dust gas vertically downward, a plurality of cyclone inlet pipes radially branched from the pipe end of the introduction pipe, and the same number of cyclone inlet pipes connected to each of the cyclone inlet pipes A cyclone is provided, and the dust gas flowing through the introduction pipe is introduced into the cyclone through the cyclone inlet pipe, and the dust is centrifuged in the cyclone.
Provided is a multi-cyclone capable of preventing a reduction in dust collection efficiency due to a reduction in gas flow velocity above a cyclone inlet.

[0010]

According to one aspect of the present invention for achieving the above object, one introduction pipe for guiding dust gas vertically downward, and a branch branched radially from a pipe end of the introduction pipe. A plurality of cyclone inlet pipes, each including the same number of cyclones as the cyclone inlet pipe connected to each of the cyclone inlet pipes, the dust gas flowing through the introduction pipe, the cyclone through the cyclone inlet pipe, the cyclone In the multi-cyclone for introducing dust into the cyclone and centrifuging the dust in the cyclone, the diameter of the introduction pipe is enlarged on the upstream side from the pipe end where the cyclone inlet pipe branches, and the inlet part of the cyclone inlet pipe Is a sloped surface such that the cyclone inlet pipe becomes narrower as approaching the cyclone. Klong is provided.

If the diameter of the inlet pipe is increased upstream of the pipe end where the cyclone inlet pipe branches, the dust gas flowing vertically upward in the inlet pipe is separated at the expanded portion. Creates a vortex. When the circulation vortex is generated, the gas passing near the circulation vortex changes its movement direction from below vertically to a horizontal direction.

Further, by forming the upper surface of the inlet portion of the cyclone inlet pipe as the above-described inclined surface, the dust gas introduced by the circulation vortex can be introduced into the upper part of the cyclone inlet pipe without being separated. Therefore, the flow rate of the gas flowing into the upper part of the cyclone inlet pipe can be increased.

As described above, a decrease in the flow velocity above the cyclone inlet pipe is prevented.

In view of the simulation results of the embodiment of the present invention described later, the enlargement ratio of the diameter of the inlet pipe is 1.4 times or more, and the inclination angle of the upper surface of the inlet of the cyclone inlet pipe is:
It is preferable to set it to 10 to 30 °.

If the inclination angle of the upper surface of the inlet portion of the cyclone inlet pipe is set to 10 ° or less, the velocity of the gas in the outer peripheral portion of the inlet pipe becomes larger vertically downward, and the gas downstream of the junction between the inlet pipe and the cyclone inlet pipe is increased. In the upper part of the cyclone inlet pipe, there is a region where the flow velocity in the horizontal direction decreases.
In addition, the angle of inclination of the upper surface of the inlet
When the angle is equal to or more than 0 °, the downward velocity component of the gas flowing from above the cyclone inlet pipe increases, and the horizontal flow velocity above the cyclone inlet pipe decreases downstream of the inclined surface of the cyclone inlet pipe.

Further, the shape of the cyclone inlet pipe is adjusted so that the lower surface of the cyclone inlet pipe on the introduction pipe side is inclined upward to reduce the gas flow, and then the lower surface of the cyclone inlet pipe on the cyclone side is inclined downward. For example, it is possible to obtain a velocity distribution in which the gas flow velocity increases in the upper part of the cyclone inlet pipe and decreases in the lower part. Also, when the lower surface of the cyclone inlet pipe is inclined in this manner, energy loss due to pressure loss can be eliminated if the cross-sectional area of the flow path of the pipe is not changed.

[0017]

BEST MODE FOR CARRYING OUT THE INVENTION

<Embodiment 1> FIG. 1 shows a first embodiment of the present invention. As shown in the figure, the multi-cyclone has one introduction pipe 1 for guiding dust gas vertically downward, a plurality of cyclone inlet pipes 2 radially branched from the end of the introduction pipe 1, and
A cyclone 3 is connected to each of the cyclone inlet pipes 2 and has the same number of cyclones 3 as the cyclone inlet pipes 2. This is a device for centrifuging dust inside.

The diameter of the inlet pipe 1 is equal to that of the cyclone inlet pipe 2.
Is expanded upstream of the branching end. The upper surface 4 of the inlet portion of the cyclone inlet pipe 2 has an inclined surface such that the cyclone inlet pipe becomes narrower as approaching the cyclone 3.

Such a multicyclone is, for example,
As shown in FIG. 2, the gas and dust flows between the pressurized fluidized bed combustion device 5 and the gas turbine 10 are as follows.

When coal, limestone and air are supplied into the pressurized fluidized bed combustion apparatus 5 to cause the coal to flow and burn, combustion gas containing dust is discharged from the pressurized fluidized bed combustion apparatus 5. This combustion gas is guided to the multi-cyclone introduction pipe 1 through the connection pipe 6. After that, the combustion gas
It flows into cyclone 3 from introduction pipe 1 via cyclone inlet pipe 2. After the dust is removed by the cyclone 3, the combustion gas is introduced into the gas turbine 10 through the cyclone outlet pipe 9. On the other hand, the dust is discharged from a leg provided at a lower portion of the cyclone 3 into the pressure vessel 7 that stores the cyclone 3, and is collected through a dust collection pipe 8.

According to the multi-cyclone proposed in this embodiment, the gas flowing vertically above the inside of the introduction pipe 1 generates a circulation vortex 11 due to the separation of the flow in a portion where the diameter of the introduction pipe 1 is increased. Let it. This is shown in FIG. FIG. 3 is a schematic longitudinal sectional view of the present multicyclone.

When the circulation vortex 11 is generated, the flow of the gas passing near the circulation vortex 11 changes from a vertically downward direction to a horizontal direction, and the gas easily flows into the upper part of the cyclone inlet pipe 2. In addition, since the inlet of the cyclone inlet pipe 2 is formed to have an inclined surface as shown in the figure, the gas introduced in the horizontal direction by the circulation vortex 11 does not peel off, and the gas flows to the upper part of the inlet of the cyclone inlet pipe 2. Can be introduced.

An example of the gas velocity distribution in the height direction of the cyclone inlet 13 is shown in FIG. As explained in the section of the prior art, if the gas flow rate at the upper part of the cyclone inlet is reduced, the dust collection rate is reduced.However, here, a piping structure that does not significantly reduce the gas flow rate at the upper part of the cyclone inlet is described. consider. In the boundary layer regions near the upper and lower wall surfaces of the cyclone inlet pipe 2, the flow velocity of the gas decreases due to the wall surface.

First, the rate of expansion of the diameter of the introduction pipe 1 (= R2 /
The relationship between (R1) and the characteristic value of the flow velocity at the upper part of the cyclone inlet (comparison point 12) ((average velocity of cyclone inlet−the velocity of upper part of cyclone inlet (comparison point 12)) / average velocity of cyclone inlet) was simulated. . The results are shown in FIG.

As can be seen from FIG. 5, when the enlargement ratio of the diameter of the introduction pipe 1 was set to 1.4 or more, a decrease in the flow velocity at the upper part of the cyclone inlet could be suppressed.

Note that the circulation vortex 11 was generated only when the enlargement ratio of the diameter of the introduction pipe 1 was set to 1.4 or more. This confirms that the reduction of the flow velocity at the upper part of the cyclone inlet can be suppressed by the action of the circulation vortex 11, in other words, if the circulation vortex is not generated, the gas at the inner and outer peripheral parts of the introduction pipe is vertically downward. This indicates that there is a possibility that the flow of gas is separated at the junction between the cyclone inlet pipe and the inlet pipe.

Next, the relationship between the inclination angle θ of the upper surface 4 of the cyclone inlet pipe and the characteristic value of the flow velocity at the comparison point 12 was simulated. The results are shown in FIG.

As shown in FIG. 6, when the inclination angle θ of the upper surface 4 of the cyclone inlet pipe is set to 10 to 30 °, the flow velocity at the comparison point 12 becomes closest to the average speed of the cyclone inlet.
This is because the velocity component of the gas flowing from the introduction pipe 1 to the cyclone inlet pipe 2 in the vertical downward direction decreases.

As described above, in this embodiment, when the enlargement ratio of the diameter of the inlet pipe is set to 1.4 times or more and the inclination angle of the upper surface of the inlet of the cyclone inlet pipe is set to 10 to 30 °. Thus, the decrease in the flow velocity at the upper part of the cyclone inlet could be suppressed.

If an internal structure for controlling the flow of gas is installed in a pipe through which dust gas of about 10 atm and 860 ° C. flows, erosion and dust clogging may occur, and the equipment may be damaged. However, according to the present embodiment, such a problem does not occur because the flow is controlled by changing only the pipe shape without installing the internal structure.

<Embodiment 2> FIG. 7 shows a second embodiment of the present invention. In this multicyclone, the upper surface 4 of the cyclone inlet pipe is curved as shown in FIG. Thus, even if the upper surface 4 is curved, the cyclone inlet pipe 2
Of the upper part of the vehicle can be suppressed. However,
It is easier to manufacture the upper surface 4 of the cyclone inlet pipe if it has an inclined surface as in the first embodiment.

<Embodiment 3> FIG. 8 shows a third embodiment of the present invention. As shown in the figure, the multi-cyclone inclines the gas flow by inclining the lower surface of the cyclone inlet pipe 2 on the inlet pipe side upward, and then inclines the lower face of the cyclone inlet pipe 2 on the cyclone 3 side downward. ing.

With such a configuration, it is possible to obtain a velocity distribution in which the gas flow velocity increases in the upper part of the cyclone inlet pipe and decreases in the lower part. In addition, when such a slope is provided, if the cross-sectional area of the cyclone inlet pipe is kept constant, energy loss due to pressure loss can be eliminated.

[0034]

According to the present invention, one inlet pipe for guiding dust gas vertically downward, a plurality of cyclone inlet pipes radially branched from the pipe end of the inlet pipe, and each of the cyclone inlet pipes are connected. Further, even in the case of a multicyclone having the same number of cyclones as the cyclone inlet pipes, it is possible to suppress a decrease in gas flow velocity at the upper part of the cyclone inlet, and to improve dust collection efficiency.

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration of a first embodiment of a multicyclone of the present invention.

FIG. 2 is a diagram showing an example of a system to which the first embodiment of the multicyclone of the present invention is applied.

FIG. 3 is a schematic longitudinal sectional view of the multicyclone shown in FIG. 1;

FIG. 4 is a diagram showing an example of a flow velocity distribution at a multicyclone inlet of the multicyclone shown in FIG. 1;

FIG. 5 is a diagram showing the relationship between the enlargement rate of the diameter of the introduction pipe of the multicyclone shown in FIG. 1 and the flow velocity at the upper part of the cyclone inlet.

FIG. 6 is a diagram showing a relationship between an inclination angle of an upper surface of a cyclone inlet pipe of the multicyclone shown in FIG. 1 and a flow velocity at an upper portion of the cyclone inlet.

FIG. 7 is a diagram showing a configuration of a second embodiment of the multicyclone of the present invention.

FIG. 8 is a diagram showing a configuration of a third embodiment of the multicyclone of the present invention.

FIG. 9 is a diagram showing the flow of gas in a conventional cyclone (part 1).

FIG. 10 is a diagram showing the flow of gas in a conventional cyclone (part 2).

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Dust gas introduction piping 2 ... Cyclone inlet piping 3 ... Cyclone 4 ... Cyclone inlet piping upper surface 5 ... Pressurized fluidized bed combustion device 6 ... Communication piping 7 ... Pressure vessel 8 ... Dust recovery pipe 9 ... Cyclone outlet pipe 10 ... Gas turbine 11 ... Circulation vortex 12 ... Comparison point of flow velocity 13,20 ... Cyclone inlet 21 ... Inner cylinder 14, 22 ... outer cylinder

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Ryuhei Kawabe 7-1-1, Omikacho, Hitachi City, Ibaraki Prefecture Inside Hitachi, Ltd. Hitachi Research Laboratory, Ltd. No. 1-1 Inside Hitachi, Ltd. Hitachi Research Laboratory (72) Inventor Hisayuki Orita 7-1-1, Omika-cho, Hitachi City, Ibaraki Prefecture Inside Hitachi, Ltd. Hitachi Research Laboratory Co., Ltd. 6-9 Takaracho Inside Kure Factory, Babcock Hitachi Co., Ltd. (72) Inventor Kazuo Ikeuchi 3-1-1 Samachi, Hitachi, Ibaraki Prefecture Inside Hitachi, Ltd. Hitachi Factory (72) Inventor Sadao Ito Hiroshima (33) Inventor Koji Tokushige 4-33 Komachi, Naka-ku, Hiroshima-shi, Hiroshima

Claims (3)

[Claims] An inlet pipe for guiding dust gas vertically downward, a plurality of cyclone inlet pipes radially branched from a pipe end of the inlet pipe, and the cyclone connected to each of the cyclone inlet pipes. A multi-cyclone comprising an inlet pipe and the same number of cyclones, introducing the dust gas flowing through the inlet pipe into the cyclone through the cyclone inlet pipe, and centrifugally separating the dust in the cyclone; The diameter of the cyclone inlet pipe is enlarged upstream of the pipe branch where the cyclone inlet pipe branches, and the upper surface of the inlet portion of the cyclone inlet pipe is inclined such that the cyclone inlet pipe becomes narrower as approaching the cyclone. Multi-cyclone characterized in that it is a surface. 2. The method according to claim 1, wherein the diameter of the introduction pipe is 1.4 times or more, and the inclination angle of the upper surface of the inlet of the cyclone inlet pipe is 10 ° to 30 °. Multi cyclone. 3. The cyclone inlet pipe according to claim 1, wherein a lower surface of the cyclone inlet pipe on the introduction pipe side is inclined upward so as not to change a cross-sectional area of the flow path of the pipe. Characterized in that the lower surface of the cyclone inlet pipe on the cyclone side is inclined downward so as not to change the flow path cross-sectional area of the multi-cyclone.