JP3509443B2 - Butterfly valve - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a butterfly valve interposed in a flow path for flowing a fluid such as a high-temperature gas containing dust such as a catalyst. 2. Description of the Related Art FIGS. 7 and 8 show an example of a conventional butterfly valve interposed in a flow path for flowing a high-temperature gas containing a catalyst. This is because the valve body 2 is rotatably disposed via the valve rod 3 in the valve box 1 in which the high-temperature gas flows in the direction of the arrow a, and faces the outer peripheral portion 2a of the valve body 2 so that the inside of the valve box 1 The backsheet 4 is projected from the peripheral surface, and the outer peripheral surface of the bleed bushing 5 inserted between the bearing cylinder 1a of the valve box 1 and the valve shaft 3 comes into contact with or approaches the end face 4a of the backsheet 4, and the bearing cylinder A purge gas supply path 6 is formed through the bleed bushing 5 and the valve rod 3 so as to communicate with the gap α between the bleed bushing 5 and the valve rod 3, and a purge gas supply pipe 7 is connected to each of the purge gas supply paths 6, A purge gas hole 8 communicating with the inside of the valve box 1 is formed through an end of the valve box 5.
Reference numeral 9 denotes a spring inserted into the bearing tube 1a, which is pressed by a pressing member 10 fixed to an end of the bearing tube 1a to press the bleed bushing 5 toward the valve body 2. In the above configuration, each purge gas supply pipe 7
To supply the purge gas into the valve box 1 from the purge gas hole 8 through the purge gas supply path 6 and the gap α.
The catalyst, dust and the like in the high-temperature gas flowing through the valve box 1 are prevented from entering the bearing cylinder. In this state, the valve stem 3
Is rotated in the forward and reverse directions to open the valve body 2 (FIG. 8).
A position) or a closed state (B position in FIG. 8). [0004] In the above conventional configuration,
As shown in FIG. 8, the catalyst D contained in the high-temperature gas easily adheres and accumulates in the concave portion 11 between the back sheet 4 and the bleed bushing 5, thereby closing the valve body 2 (position B in FIG. 8). When the valve body 2 and the back seat 4
Therefore, the valve body 2 cannot be fully closed with the catalyst D interposed therebetween, which may hinder plant operation. In view of the above problems, an object of the present invention is to provide a butterfly valve in which dust such as a catalyst is prevented from adhering and accumulating in a concave portion between a back sheet and a bleed bushing. [0006] In order to achieve the above object, the invention according to the first aspect is directed to a valve body in a valve box interposed in a flow path for flowing a fluid such as a high-temperature gas containing dust. Is disposed rotatably via a valve rod, a backsheet is protrudingly provided on the inner peripheral surface of the valve box so as to face the outer peripheral portion of the valve body, and between the bearing cylinder and the valve shaft of the valve box. An outer peripheral surface of the bleed bushing inserted into the backsheet abuts or approaches an end surface of the back sheet, and a purge gas supply passage penetrating through the bearing cylinder and the bush and communicating with a gap between the bleed bushing and the valve stem is formed. In the butterfly valve, a purge gas passage communicating with the purge gas supply passage and opening to face a concave portion between the back sheet and the bleed bushing is formed in the bearing cylinder. In the above configuration, by supplying the purge gas from the purge gas supply passage to the gap between the bleed bushing and the valve rod, the catalyst, dust, etc. in the high-temperature gas flowing in the valve box pass through the bearing cylinder. By injecting the purge gas from the purge gas supply passage through the purge gas passage toward the concave portion between the back sheet and the bleed bushing, dust such as catalyst adheres and accumulates in the concave portion. Can not be. In this case, the purge gas is ejected from the purge gas passage toward the concave portion between the back sheet and the bleed bushing so that dust such as the catalyst does not adhere to the concave portion and is deposited. Can be fully closed. Further, since it is sufficient to form only the purge gas passage in the bearing cylinder of the existing butterfly valve, the structure is simple, the production cost is hardly increased, and it is economical. An embodiment of the present invention will be described below with reference to the drawings. FIGS. 1 to 3 show a butterfly valve according to an embodiment of the present invention.
In addition, a purge gas passage 13 communicating with the purge gas supply passage 6 and opening to face the concave portion 11 between the back sheet 4 and the bleed bushing 5 is formed. Since the configuration other than the above is substantially the same as the conventional example shown in FIGS. 7 and 8, the same portions are denoted by the same reference numerals and description thereof will be omitted. In the above configuration, each purge gas supply pipe 7
By supplying the purge gas into the valve box 1 from the purge gas hole 8 through the purge gas supply path 6 and the gap α from the inside, the catalyst, dust and the like in the high-temperature gas flowing through the valve box 1 do not enter the bearing cylinder. You can do so. The back sheet 4 passes through the purge gas passage 13.
The purge gas is ejected toward the recess 11 between the bleed bushing 5 and the
Is prevented from adhering and accumulating, so that the valve body 2 can be completely closed (the position B in FIG. 2) without fail. In this case, the bearing sleeve 1 of the existing butterfly valve is used.
Since it is only necessary to form the purge gas passage 13 in "a", the structure is simple, the production cost is hardly increased, and it is economical.
4 to 6 show a butterfly valve according to another embodiment of the present invention, in which an end of a bleed bushing 5 communicates with a gap α between the bleed bushing 5 and the valve stem 3. In addition, a purge gas hole 14 that opens to face the concave portion 11 between the back sheet 4 and the bleed bushing 5 is provided therethrough. According to the above configuration, the purge gas is supplied to the gap α between the bleed bushing 5 and the valve rod 3 as in the embodiment shown in FIGS.
The catalyst, dust and the like in the high-temperature gas flowing through the inside can be prevented from entering the bearing cylinder, and the purge gas is ejected from the purge gas hole 14 toward the concave portion 11 between the back sheet 4 and the bleed bushing 5. Since the catalyst D is prevented from adhering and accumulating in the concave portion 11, the valve body 2 can be completely closed (the position B in FIG. 5) without fail.
Note that the purge gas hole 8 may be omitted depending on the degree of opening of the valve that is always used. In this case, since it is only necessary to form the purge gas hole 14 in the bleed bushing 5 of the existing butterfly valve, the structure is simple, the production cost is hardly increased, and it is economical. By combining the above two embodiments, the purge gas passage 13 may be formed in the bearing cylinder 1a, and the purge gas hole 14 may be formed in the bleed bushing 5. As a result, the catalyst D can be more reliably prevented from adhering and depositing in the concave portion 11 between the back sheet 4 and the bleed bushing 5. According to the first aspect of the present invention, the purge gas is ejected from the purge gas passage toward the concave portion between the back sheet and the bleed bushing, and dust such as catalyst adheres and accumulates in the concave portion. In this way, the valve can be completely closed. Further, since it is sufficient to form only the purge gas passage in the bearing cylinder of the existing butterfly valve, the structure is simple, the production cost is hardly increased, and it is economical. [0019]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a longitudinal sectional view of a butterfly valve according to an embodiment of the present invention. FIG. 2 is a view as viewed in the direction of arrows AA in FIG. 1; FIG. 3 is a perspective view of the main part. FIG. 4 is a longitudinal sectional view of a butterfly valve according to another embodiment of the present invention. FIG. 5 is a view taken in the direction of arrows BB in FIG. 4; FIG. 6 is a perspective view of the main part. FIG. 7 is a half sectional front view of the entire butterfly valve showing a conventional example. FIG. 8 is a view as viewed in the direction of arrows CC in FIG. 7; DESCRIPTION OF SYMBOLS 1 Valve box 1a Bearing cylinder 2 Valve body 2a Outer peripheral portion of valve body 3 Valve rod 4 Back sheet 4a End face of back sheet 5 Bleed bushing 6 Purge gas supply path 11 Depression 13 between back sheet and bleed bushing Purge gas passage 14 purge gas hole 20 bush D catalyst (dust) α gap between bleed bushing and valve stem

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int.Cl. ⁷ , DB name) F16K 1/22-1/54 F16K 27/02

Claims (1)

(57) [Claims 1] A valve body is rotatably disposed via a valve rod in a valve box interposed in a flow path through which a fluid such as a high-temperature gas containing dust flows. A back sheet protrudes from an inner peripheral surface of the valve box so as to face an outer peripheral portion of the valve body, and an outer peripheral surface of a bleed bushing inserted between a bearing cylinder of the valve box and a valve shaft is formed of the back sheet. In the butterfly valve, which is provided with a purge gas supply path which is in contact with or close to an end face, penetrates the bearing cylinder and the bush, and communicates with a gap between the bleed bushing and the valve rod, the purge gas supply to the bearing cylinder is performed. A butterfly valve, wherein a purge gas passage is formed so as to communicate with the passage and open to face an upstream recess between the back seat and the bleed bushing.