JPH1147640A - Cyclone system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable blow down by using a pressure difference in a system by disposing a structure in which an outer diameter is set to specified times of an inner diameter of a waste gas inner cylinder at a lower part of a solid removing device arranged in a pressure vessel and connecting a solid particle removing part of the pressure vessel and outlet piping with piping. SOLUTION: A combustion gas generated in a pressure fluidized bed combustion device where a fluidized bed combustion of coal is executed is introduced to a cyclone 3 as the solid removing device through connecting piping 2. Relating to the cyclone 3, dust is separated by centrifugal force during a fluidization allowing to fall while revolving and a purified gas is discharged from the waste gas inner cylinder 7. At this time, a part of the gas in a dust hopper is introduced to a gas turbin 10 by bleeding by the blow down through the blow-down piping 9 connecting the dust hopper and the outlet piping 8. The structure having the diameter of 0.65 times of the inner diameter of the waste gas inner cylinder 7 of the cyclone 3 is disposed in a dust banker of the cyclone 3 to prevent a reversed inflow of the waste gas.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a solid removing apparatus (hereinafter referred to as a cyclone) for separating and removing solid particles in a gas by centrifugal force, and more particularly to a multicyclone dust hopper (solid particle recovery) comprising a plurality of cyclones. Part) relates to a cyclone system in which gas is extracted from the cyclone system.

[0002]

2. Description of the Related Art A cyclone is a centrifugal dust collector widely used industrially because it has a simple structure and has no moving parts.

As a means for improving the dust collection efficiency of a cyclone, first, as shown on page 143 of "Cyclone Separator" (1980, Kato Nakamichikan), a structure (vortex cut-off cone) is placed in the cyclone. There is a way to install. However, when the structure is installed in the cyclone, the support of the structure acts as a flow resistance, and the swirling flow is weakened, so that the dust collection efficiency may be reduced. Further, dust may accumulate between the structure and the cyclone main body, block the cyclone, and reduce the dust collection efficiency. Therefore, an optimal design is required for the cyclone in which the structure is installed.

[0004] Next, as a means for improving the dust collection efficiency of the cyclone, a part of the gas in the cyclone is transferred from a dust hopper below the cyclone as described on page 396 of "Powder Engineering Handbook" (1965, Asakura Shoten). There is a blowdown to bleed. By the way, when blowdown is performed in a cyclone system under a high temperature and a high pressure, which is a target of the present invention, there is a problem that if the extracted gas is discharged to the outside of the system as it is, energy loss becomes large. Therefore, it is necessary to return the gas into the system. Here, as a technique for recycling blown-down gas, there are examples disclosed in JP-A-55-44368 and JP-B-6-98255. The former discloses a device in which dust separated by a dust collector is extracted together with a gas from a discharge pipe, separated by a cyclone, and then only the gas is returned to the upstream of the dust collector by using a blower. The latter is provided with a dust hopper connected to the lower part of the louver type dust collector by a dust extraction pipe, and this dust extraction pipe and the exhaust gas duct on the upstream side of the main exhaust fan on the downstream side of the louver type dust collector, It discloses an exhaust gas treatment device connected by a blowdown pipe provided with a blowdown dust collector.
In this apparatus, after cooling the gas from the converter, the dust is removed by a louver type dust collector. Both devices use an air blower for blowdown.However, in a cyclone system under high temperature and high pressure, there is also a problem that blowdown using an air blower cannot be performed because the blower is exposed to high temperature and has a problem in strength. is there.

[0005]

SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a cyclone system having a structure in a cyclone under a high temperature and a high pressure so that blowdown can be performed by utilizing a pressure difference in the system.

[0006]

Means of the present invention to achieve the above object is to introduce a gas containing solid particles from an inlet pipe tangentially attached to a cylinder, to impart an angular momentum to the gas, A solid removing device for separating and removing solid particles therein by centrifugal force is provided in a pressure vessel, and the solid particles are collected in the pressure vessel via a tubular leg of the solid removing device, and the gas from which the solid particles are removed is supplied to the pressure vessel. In a cyclone system configured to be taken out through an exhaust inner cylinder disposed on an upper central axis of the solid removing device and an outlet pipe connected to the exhaust inner cylinder, a cyclone system disposed on the lower central axis of the solid removing device A structure having a diameter of 0.65 times the outer diameter of the exhaust inner cylinder, which is disposed axially symmetrically with the upper part, and a pipe connecting the solid particle collection part of the pressure vessel and the outlet pipe, is provided. Features.

The inventors have studied what kind of structure should be installed at the center of the cyclone tube in order to improve the dust collecting performance of the cyclone. First, the gas flow of a cyclone having a structure at the center of the pipe was calculated. According to calculations,
If there is a structure in the center of the cyclone, the structure becomes a resistance to the flow, and the swirling force is weakened below the structure.
Therefore, the low pressure region in the center of the cyclone caused by the turning does not exist below the structure. At this time, they found that if the outer diameter of the structure was 0.65 times or more the diameter of the exhaust inner cylinder, the pressure in the lower part of the structure would be higher than the pressure in the cyclone outlet pipe. That is, the pressure of the dust hopper becomes higher than the pressure of the cyclone outlet pipe. Therefore, by providing a blowdown pipe connecting the dust hopper and the cyclone outlet pipe in this state, it is possible to perform blowdown using a pressure difference in the system.

If the inner diameter of the legs of the cyclone is smaller than the outer diameter of the structure, the swirling vortex is blocked by the structure, so that the gas flowing into the cyclone flows below the structure outside the structure. Inside the diameter (region where the distance from the center axis of the cyclone is smaller than the radius of the structure)
Does not flow into

If the inner diameter of the legs of the cyclone is smaller than the outer diameter of the structure, the gas flowing into the cyclone does not flow inside the outer diameter of the structure at the lower part of the structure. If the support of the structure is installed inside the diameter of the object (region where the distance from the center axis of the cyclone is smaller than the radius of the structure), the support of the structure does not affect the swirling flow upstream .

[0010]

FIG. 1 shows a first embodiment of the present invention. In the cyclone system of this embodiment, the gas inlet side is connected to the pressurized fluidized bed combustion device 1 by the communication pipe 2, and the gas outlet side is connected to the gas turbine 10 via the cyclone outlet pipe 8. As shown in the drawing, the cyclone system of the present embodiment has a head having a hemispherical wall surface, a cylindrical intermediate portion concentrically connected to a circular cross section of the open end of the head, and a concentric center at the other end of the intermediate portion. A pressure vessel 5 comprising a truncated conical bottom portion to which a large-diameter end is connected, and a head section and a dust hopper disposed between the head and the intermediate portion, substantially perpendicular to the central axis of the pressure vessel 5. That is, a partition wall 5a that divides into a body-side section that forms a solid particle recovery section, a gas introduction pipe 5b that is arranged on the central axis of the pressure vessel 5 and penetrates the wall surface of the head and the partition wall 5a, Align the axis with the pressure vessel 5
A plurality of cyclones 3 that are installed substantially parallel to the central axis of the pressure vessel 5 and are connected to the gas introduction pipe 5b, a dust collection pipe 6 that is connected to a small-diameter end of a truncated cone-shaped bottom of the pressure vessel 5, It is configured to include a cyclone outlet pipe 8 connected to the head section of the container 5, and a blowdown pipe 9 communicating the cyclone outlet pipe 8 with the trunk-side section of the pressure vessel 5.

The cyclone 3 has an axisymmetric body 3a.
And an inlet pipe 3 connecting the main body 3a and the gas introduction pipe 5b
b, an exhaust inner cylinder 7 arranged on the central axis of the upper part of the main body 3a, one end of which opens into the main body 3a and the other end of which opens in the head section of the pressure vessel 5, and is concentric with the lower end of the main body 3a. A tubular leg 4 connected to the body and opening in the torso compartment;
a supported at the lower end of the main body 3a by a support 12 at the lower end of the main body 3a. The inlet pipe 3b is tangentially connected to the outer circumference of the main body 3a, and the opening position of the exhaust inner cylinder 7 in the main body 3a is closer to the leg 4 side (hereinafter, the leg 4 side is lower than the connection position of the inlet pipe 3b). , The exhaust inner cylinder 7 side will be described as an upper side). Body 3a
Is a cylindrical portion to which the inlet pipe 3b and the exhaust inner cylinder 7 are connected, a conical portion having a large-diameter end concentrically connected to the lower end of the cylindrical portion, and a concentric portion to the small-diameter end of the conical portion. The tubular leg 4 is connected to the lower end of the dust bunker.

The structure 11 has a conical shape, and is arranged concentrically with the dust bunker with its tip facing upward. The front end of the structure 11 is located at the center of the small-diameter end of the conical portion, and the bottom surface is supported by the support 12 at the lower end of the dust bunker. The size of the support 12 is the structure 1
When the support 1 and the support 12 are projected in the direction of the central axis of the main body 3a, the projection area of the support 12 is set to a size that fits in the projection area on the bottom surface of the structure 11. In other words, body 3
The maximum radius of the support 12 measured from the central axis of a is smaller than the radius of the outer periphery of the bottom surface of the structure 11 measured from the central axis of the main body 3a. The outer diameter of the bottom surface of the structure 11 is 0.8 times the inner diameter of the inner cylinder 7 of the exhaust.
Is smaller than the outer diameter of the bottom surface of the structure 11. The outer diameter of the bottom surface of the structure 11 is smaller than the diameter of the small diameter end of the conical portion.

The flow of gas and dust in the cyclone system having the above configuration is as follows. First, coal, limestone, and air are supplied into the pressurized fluidized bed combustion device 1 to perform coal fluidized bed combustion. The combustion gas (gas containing solid particles) generated in the fluidized bed combustion is discharged from the pressurized fluidized bed combustion device 1 and introduced into the cyclone body 3a through the communication pipe 2, the gas introduction pipe 5a, and the inlet pipe 3a. You. The gas introduced into the cyclone main body 3a descends while turning inside the cyclone main body 3a, and the flow reverses from descending to ascending at a point at the lower portion of the cyclone main body 3a. The solid particles contained in the gas move toward the inner peripheral wall of the cyclone main body 3a by centrifugal force due to the swirling, and fall along the inner peripheral wall. The gas from which the solid particles (hereinafter referred to as dust) are removed by the cyclone body 3a and whose flow direction is reversed flows out of the exhaust inner cylinder 7 through the center of the cyclone. The gas flowing out of the exhaust inner cylinder 7 is introduced into the gas turbine 10 from the cyclone outlet pipe 8 through the head section. Further, a part of the gas in the trunk side section (dust hopper) is extracted by blowdown through a blowdown pipe 9 connecting the trunk side section (dust hopper) and the cyclone outlet pipe 8, and is guided to the gas turbine 10.

On the other hand, dust that has fallen along the inner peripheral wall surface of the cyclone body 3a passes through a dust bunker and enters the trunk side section of the pressure vessel 5 that houses the cyclone body 3a from the cyclone legs 4 below the cyclone body 3a. Discharged,
The dust is collected through the dust collection pipe 6.

FIG. 2 shows a pressure distribution in a direction (radial direction) from the central axis in the cyclone 3 to the outer peripheral portion. As shown in the figure, the pressure hardly changes in the direction from the upper part to the lower part of the cyclone (in the direction of the central axis), and the pressure distribution in the radial direction in the cyclone is low in the central part and high in the outer peripheral part. The pressure at a distance of 0.65 times the radius of the exhaust inner cylinder 7 from the center of the cyclone is substantially equal to the average pressure of the exhaust inner cylinder 7, that is, the pressure in the cyclone outlet pipe 8.
In order to perform blowdown, the pressure in the trunk-side section of the pressure vessel 5 must be equal to or higher than the above average pressure.

The cyclone system of the present invention has a structure 1
Since the outer diameter of 1 is at least 0.65 times the diameter of the exhaust inner cylinder 7, a region in the center of the cyclone where the pressure is lower than the average pressure of the exhaust inner cylinder 7 is prevented from reaching the lower part. Therefore, the pressure in the trunk-side section of the pressure vessel 5 becomes higher than at least the average pressure of the exhaust inner cylinder 7, that is, the pressure in the cyclone outlet pipe 8, so that the pressure difference in the system alone can be obtained without using an exhaust fan. The gas in the side compartment can be blown down to the cyclone outlet pipe 8.

FIG. 3 shows gas flow lines in a vertical section of the cyclone body 3a. In this drawing, the vertical flow lines of the flow are shown, and the circumferential flow is ignored. As shown in the figure, since the inner diameter of the cyclone leg 4 is smaller than the outer diameter of the bottom surface of the structure 11, the gas flow flowing into the cyclone flows into the lower part of the structure 11 inside the diameter of the structure 11. do not do. Therefore, in the lower part of the structure 11, the support 1 that supports the structure 11 in a region inside the diameter of the structure 11.
The presence of 2 does not affect the upper swirl flow. If the swirling flow is affected, the gas velocity in the swirling direction decreases and the centrifugal force acting on the dust also decreases, so that the dust collection efficiency decreases. The support 12 is desirably formed of several columns as shown in FIG.

Also, the inner diameter of the cyclone leg 4 is
1, the swirl flow reaches the inside of the body side section of the pressure vessel 5, and the dust once separated by centrifugation and collected in the pressure vessel 5 is returned from the pressure vessel 5 to the cyclone body 3a.
There is a possibility that the dust collection rate may be reduced by being swirled by the flow returning to However, in the above embodiment, since the inner diameter of the cyclone leg 4 is smaller than the outer diameter of the structure 11, the gas flow is
It is possible to avoid the possibility that the dust is inverted and ascended without reaching the inside of the pressure vessel 5 to be discharged from the cyclone through the exhaust inner cylinder 7 to lower the dust collection rate.

[0019]

According to the present invention, blowdown can be performed only at a high pressure and a low pressure in a system under high temperature and high pressure.

[Brief description of the drawings]

FIG. 1 is a system configuration diagram showing an embodiment of the present invention.

FIG. 2 is a conceptual diagram showing a relationship between a radial position in a cyclone body and a pressure at that position.

3 is a sectional view showing streamlines in a vertical section of the cyclone shown in FIG. 1. FIG.

FIG. 4 is an enlarged perspective view showing a part in which the structure and the support of the cyclone shown in FIG. 1 are installed.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Pressurized fluidized bed combustion apparatus 2 Communication pipe 3 Cyclone 3a Main body 3b Inlet pipe 4 Cyclone leg 5 Pressure vessel 5a Partition wall 5b Gas introduction pipe 6 Dust recovery pipe 7 Exhaust inner cylinder 8 Cyclone outlet pipe 9 Blowdown pipe 10 Gas turbine 11 Structure 12 Support for Structure

 ──────────────────────────────────────────────────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. (72) Inventor Tomohiko Miyamoto 7, Omikacho, Hitachi City, Ibaraki Prefecture 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. (72) Inventor Kazuo Ikeuchi Hitachi, Ibaraki Prefecture 3-1-1, Sachimachi Hitachi, Ltd. Hitachi Plant (72) Inventor Shoji Kuramoto 6-9 Takaracho, Kure City, Hiroshima Prefecture Babcock Hitachi Co., Ltd. Kure Plant (72) Inventor Sadao Ito Hiroshima City, Hiroshima Prefecture 4-33 Komachi, Naka-ku Chugoku Electric Power Co., Inc.

Claims (3)

[Claims] 1. A solid removing device which introduces a gas containing solid particles from an inlet pipe attached in a tangential direction of a cylinder, gives angular momentum to the gas, and separates and removes the solid particles in the gas by centrifugal force. The solid particles are collected in the pressure vessel via the tubular legs of the solid removing device, and the gas from which the solid particles have been removed is discharged into the exhaust disposed on the central axis line of the upper portion of the solid removing device. In the cyclone system, which is configured to be taken out through a cylinder and an outlet pipe connected to the exhaust inner cylinder, the solid removing device is disposed on a lower central axis, the upper part is symmetrical, and the outer diameter is the inner diameter of the exhaust inner cylinder. A cyclone system comprising: a structure having a diameter exceeding 0.65 times the diameter of the pressure vessel; and a pipe connecting the solid particle collection section of the pressure vessel and the outlet pipe. 2. The cyclone system according to claim 1, wherein an inner diameter of the tubular leg of the solid removing device is smaller than an outer diameter of the structure. 3. The cyclone system according to claim 2, wherein the structure is disposed below the structure, and an outer diameter of the structure is defined as an outer diameter about a center axis of the solid removing device. The cyclone system is supported by a solid removal device via a support provided inside a cylindrical region to be formed.