JPH083782Y2 - Valve seat - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial field of application> The present invention relates to a valve seat used for a dust collecting / cutting-out damper in a dust collecting apparatus, a damper for discharging other particulate matter, and the like.

<Prior Art> An example of the above-mentioned damper is an ash treatment damper provided in a dust collector of a thermal power plant. FIG. 2 is a sectional structural view showing an example of this damper. The ash 21 collected by a dust collector (not shown) is temporarily stored in the hopper 22. A damper 11 is provided at the lower end of the hopper 22, and the hopper can be opened by opening the damper 11.
The ash 21 stored in 22 is cut out to the outside. 2 (a) shows a state in which the damper 11 is closed, and FIG. 2 (b) shows a state in which the damper 11 is opened.
The damper 11 in this example is opened and closed by driving the cylinder 23. The damper 11 is composed of a valve seat 12 and a valve plate 13, and the valve plate 13 is connected to the cylinder 23 via a cylinder rod 23a. The valve seat 12 is conventionally made of metal such as carbon steel or stainless steel, and the flange 12a integrally provided on the upper end thereof is generally fixed to the flange 22a provided on the hopper 22 by a well-known bolt or the like. Met.

By the way, the opening and closing of the damper 11 in the above-mentioned thermal power plant often reaches more than 10,000 times a year.
The front end surface 12b of the valve seat 12 is repeatedly hit by the valve plate 13 and is subjected to a severe gas cut due to a pressure difference between the inside of the hopper and the outside air, etc.

<Problems to be Solved by the Invention> The front end surface of the valve seat exposed under the above-mentioned conditions of use is significantly worn out in a short period of time, and usually requires replacement by opening and closing the damper 2,000 to 4,000 times. A large number of dampers are installed in a thermal power plant, so that it takes a lot of time and labor to manufacture and replace valve seats, and the maintenance cost thereof is extremely expensive.

In order to solve such a problem, attempts have recently been made to improve wear resistance by using ceramics for a part of the valve seat. FIG. 3 is a sectional view showing an example thereof, and FIG. 3 (a) shows a valve in which a ceramic ring 122a is adhesively fixed to the tip of a metal base 121a with an inorganic or organic adhesive or brazing. The sheet 120a is configured, and FIG. 3 (b) shows the metal base 121b described above.
A groove 121b ₁ is bored inside the tip of the valve seat 12 and the ceramic ring 122b is adhered to the groove 121b ₁ with an adhesive or a brazing material, or is fixed by a known shrink fit.
This is the structure of 0b.

However, in the valve seat 120a having the structure shown in FIG. 3 (a), the front end surface subjected to the repeated load by the valve plate 13
Since 122a ₁ does not have a metal part that protects the ceramic ring 122a, the ceramic ring 122a, which has a weak impact force as a general characteristic, is easily broken, and expensive ceramics with excellent impact resistance are used to eliminate the problem of destruction. Even if it is used, there is a problem that the bonding strength of the adhesive cannot withstand repeated load and the adhesive separates at the bonded portion.

On the other hand, in the valve seat 120b having the structure shown in FIG. 3 (b),
Since the base 121b protects the ceramic ring 122b, the durability of the ceramic ring 122b against breakage from repeated loading is significantly improved. However, when the ceramics ring 122b and the metal base 121b are bonded with an adhesive, the bonding force is lost due to repeated load, and the ceramics ring 122b falls out. In addition, the method by shrink fitting is superior in the durability of the joint strength against repeated load as compared with the method by the adhesive, but the ash treatment of the thermal power plant described above has a temperature of 200 ° C or higher in normal operation, The temperature of the valve seat itself becomes 200 ° C. or higher, and when it is used for operation at such a high temperature, the linear expansion coefficient of the ceramic ring 122b is smaller than that of the die 121b, so the joining force for shrink fitting decreases. There was a problem.

The present invention was devised in order to fundamentally solve the problems in the above-mentioned conventional means.
Moreover, it is an object to provide a valve seat that exhibits excellent durability even under the above-mentioned adverse conditions where a high load acts, and to significantly reduce various costs, labor, and time involved in replacement. To do.

<Means for Solving the Problems> The concrete means of the present invention for solving the above-mentioned problems is
It will be described with reference to the drawings.

In FIG. 1, 3 is a die made of metal such as carbon steel and stainless steel, 2 is alumina, silicon carbide,
A seat ring made of ceramics such as silicon nitride and zirconia. Reference numeral 4 denotes a fastening ring made of a unidirectional shape memory alloy having a function to be described later, which is fitted around the outer periphery of the mouth ring 3 in a state where the seat ring 2 is in contact with the tip. The outer circumferences of the seat ring 2 into which the fastening ring 4 is fitted and the tip portion 30 of the base 3 have substantially the same outer diameter,
The seat ring 2 is integrally fixed to the mouthpiece 3 by fitting the fastening ring 4 on the smooth surface to form the valve seat 1. The fastening ring 4 is fitted so that its front end surface 4a and the front end surface 2a of the seat ring 2 form the same level, that is, the same plane 2a ₀ .

<Operation> In the valve seat 1 of the present invention, the seat ring 2 is brought into contact with the tip of the base 3 as described above, and the fastening ring 4 is fitted in this state, and is integrally fixed through the fastening ring 4. Composed. The fastening ring 4 and the tip surfaces 4a, 2a of the seat ring 2 are configured to form the same plane 2a ₀ ,
The outer circumference of the seat ring 2 is completely surrounded by the fastening ring 4. For this reason, the durability of the valve seat 1 is dramatically improved by reinforcing the defect of the ceramic seat ring 2 which is excellent in wear resistance but weak in impact force with the fastening ring 4 made of shape memory alloy which is excellent in impact resistance. It is possible to improve. The shape memory alloy applicable to the fastening ring 4 is
The diameter of the seat ring 2 formed on the smooth surface and the outer diameter of the tip end portion 30 of the die by heating to a predetermined temperature (hereinafter collectively referred to as "smooth surface outer diameter") are smaller in one direction. Shaped items such as Ni-Ti series, Cu series, F
An e-based one can be used. In particular, Fe-based materials have a high shape recovery temperature of 120 to 320 ° C., and therefore have high bond strength even when the environment temperature is high, and can effectively exhibit the functions required for the present invention.

FIG. 4 is an exploded view for explaining an example of the manufacturing means of the valve seat 1 according to the present invention. The outer diameter Dc of the seat ring 2 and the outer diameter Dm of the tip portion 30 of the base 3, that is, the fastening ring 4
The outer diameters Dc and Dm of the smooth surface to which is fitted are the same outer diameter and are formed as smooth surfaces. It is desirable to secure an accuracy of about | Dc−Dm | ≦ 0.1 (mm) for this smooth surface in machining. Further, it is preferable that the inner diameter dc of the seat ring 2 and the inner diameter dm of the mouthpiece 3 have substantially the same diameter so that a step or the like and the discharged powder or granules do not stay.

On the other hand, the fastening ring 4 is memorized in advance in such a shape that the diameter thereof is reduced by heating, and thereafter the diameter is expanded to an inner diameter slightly larger than the outer diameter of the smooth surface. The inner diameter ds after the diameter expansion is within a range in which the difference between the outer diameter Dc of the seat ring 2 and the outer diameter Dm of the tip 30 of the die, whichever is larger, satisfies the following expression (1). It is preferable to do so.

0 <ds−Do ≦ k · ε · ds (1) In the formula (1), ε is the shape recovery strain, and the change in the inner diameter of the fastening ring 4 due to heating for the shape recovery is the shape recovery strain ε. And the inner diameter ds of the fastening ring 4 (ε ・ ds)
Given in. k is a coefficient of 1 or less, and the smaller the bond strength, the higher the bonding strength. In the case of Fe-based shape memory alloy, ε is about 0.02, and this value can be obtained by heating to 120 to 320 ° C.

As described above, the fracture toughness and wear resistance of the surface 2a ₀ of the valve seat 1 contacting the valve plate 13 can be secured by combining the seat ring 2 and the fastening ring 4. Thus, when the valve plate 13 is closed, the fastening ring tip surface 4a and the seat ring tip surface 2a form the same plane 2a ₀ so that the valve plate 13 contacts the seat ring 2 and the fastening ring 4 at the same time. The effect can be exerted more effectively. That is, the sum of the length lm of the smooth surface 30 of the base 3 and the length lc of the seat ring 2 may be equal to the length ls of the fastening ring 4.

Thus, in order to manufacture the valve seat 1 of the present invention, the mouthpiece 3, the seat ring 2, and the fastening ring 4 which are formed so as to meet the above-mentioned dimensional conditions are prepared. Fastening ring 4
After performing the shape memory processing described above, the diameter is expanded to an inner diameter slightly larger than the outer diameter of the smooth surface. After that, the seat ring 2 is brought into contact with the tip of the mouthpiece 3, and the fastening ring 4 is fitted to the outer periphery of the seat ring 2, that is, the smooth surface.
Next, the fastening ring 4 is heated and contracted to a previously memorized shape. Due to this contraction, the fastening ring 4 is fitted on the smooth surface, and the base 3 and the seat ring 2 are firmly fixed.

The reason why the fixing means using the fastening ring 4 made of such a shape memory alloy is superior to the shrink fitting fixing means is that the recovery strain of the shape memory alloy is much larger than the linear expansion strain in the shrink fitting. The recovery strain of memory alloy reaches more than 2%.

In the embodiment shown in FIG. 1, the smooth surface is a parallel surface, that is, a straight tube, and the outer diameter of the fastening ring 4 is the base 3
A notch was provided on the outer circumference of the mouthpiece 3 so as to be approximately the same as the outer diameter of the fastening ring 4. However, if there is no facility restriction on the outer peripheral portion of the valve seat 1, as shown in FIG. May be fitted. Also, the sixth
As shown in the figure, the taper θ ₁ or θ ₂ may be provided on both or one of the smooth surfaces of the seat ring 2d and the mouthpiece 3d so that the contact surface side of the seat ring 2d and the mouthpiece 3d becomes thick. .

In this way, by providing the taper θ ₁ and θ ₂ such that the contact surface side of the seat ring 2d and the base 3d becomes thick, for example, the temperature becomes high enough to significantly reduce the joining force of the fastening ring 4d during operation. Even in such a case, it is possible to avoid the trouble caused by the falling of the seat ring 2d. In order to prevent the ceramics from falling off, a curved shape may be used instead of a linear taper, but it is not practical because it becomes a complicated shape. In the present invention, the term "same smooth surface" is a generic term for a tapered surface as shown in FIG. 6 in addition to the parallel surfaces described above. In either case, the outer diameter of the smooth surface of the seat ring 2 and the base 3 is Production error
It is preferable that the thickness is within about 0.1 mm.

<Example> A valve seat based on the present invention was attached to a cyclone type dust collector in a thermal power plant, and durability was investigated. The structure of the valve seat of the present invention is the same as that shown in FIG. 1, and as a comparative example, a conventional product in which the valve seats are all made of metal was simultaneously mounted, and their durability was compared and investigated. The specifications and usage conditions of the valve seat are as shown in Table 1.

Under such conditions, the life of conventional valve seats was about 3 to 6 months on average. On the other hand, the valve seat of the present invention had no troubles such as the seat ring coming off or missing even after one year, and the wear was slight.

<Effect of the Invention> The provision of the valve seat of the present invention makes it possible to significantly extend the life of the valve seat. As a result, it has become possible to greatly reduce various costs, labor, and time involved in valve seat replacement.

[Brief description of drawings]

FIG. 1 is a sectional view showing an embodiment of a valve seat according to the present invention, FIG. 2 is a sectional structural view showing an example of a damper for a dust collector, and FIG. 2 (a) is a damper closed and FIG. b)
Indicates that the damper is open. FIG. 3 is a sectional view showing an example of a conventional valve seat, FIG. 4 is an exploded view for explaining an example of a valve seat manufacturing means based on the present invention, and FIG.
FIG. 6 and FIG. 6 are sectional views showing other different embodiments according to the present invention. 1: valve seat, 2: seat ring, 3: base, 4: fastening ring, 11: damper, 12,120a, 120b: valve seat, 12a: flange, 121a, 121b: base, 122a, 122b: ceramics ring, 13: Valve plate, 21: gray, 22: hopper, 22a: flange, 23: cylinder, 23a: cylinder rod.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-60-146910 (JP, A) JP-A-62-127405 (JP, A) Jikken-Sho 62-8463 (JP, Y2)

Claims (1)

[Scope of utility model registration request] 1. A valve seat having a ceramic seat ring fixed to the tip of a metal mouthpiece, wherein the outer diameters of the seat ring and the tip of the mouthpiece are formed on the same smooth surface, and the smooth surface is unidirectional. A fastening ring made of a flexible shape memory alloy is fitted so that the leading end surface of the fastening ring and the leading end surface of the seat ring form the same plane, and the seat ring and the mouthpiece are integrally fixed to each other. Valve seat to be used.