JP3058532B2 - Ceramic ventilation control valve - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a high-temperature, high-pressure, high-velocity flow of 900 ° C. or more, such as a blower tube of a blast furnace hot stove, a heat recovery tube of an industrial heating furnace or a tunnel kiln, and a tuyere of a blast furnace for steelmaking. The present invention relates to a ceramic ventilation control valve for controlling the flow rate of compressed air or hot air.

[0002]

2. Description of the Related Art Conventionally, a gas having a high temperature, a high pressure and a high flow rate of 900 ° C. or more, particularly used in a blower tube of a blast furnace hot stove, a heat recovery tube of an industrial heating furnace or a tunnel kiln, a tuyere of a blast furnace for steelmaking, etc. Since the flow rate of compressed air or hot air is controlled only by controlling the output of a blower, a valve capable of controlling the flow rate of the high-temperature, high-pressure, high-flow rate gas in a blower pipe has been desired.

In response to the above demands, various attempts have been made in the past to form a valve main body with a heat-resistant metal and further employ a water-cooled structure to compensate for the lack of heat resistance of the valve. Under the above-mentioned high temperature, the temperature of the passing gas is significantly lowered by water cooling, and the heat loss is extremely large.

In order to solve the above-mentioned drawback, the valve plate and the valve shaft are made of ceramics, and the thickness of the valve plate along the axis of the valve shaft is reduced as the distance from the mounting portion of the valve shaft decreases. A high-temperature butterfly valve having a cantilevered plate is proposed in Japanese Utility Model Publication No. 63-46771.

[0005]

In the butterfly valve for high temperature, when the valve is fully opened, that is, even when the valve plate is supported in parallel to the flow of gas, the pressure loss is different between before and after the valve portion. Although not so large, this high-temperature butterfly valve has a valve element 14 which forms a butterfly valve as shown in FIG.
The valve shaft 14 and the valve shaft 15 are integrally formed, and when a high pressure is applied when the valve is fully closed, the valve body 14 and the valve shaft 15 have a cantilever structure. At the same time, the operation was not smooth, and the connecting portion 16 and the valve shaft 15 themselves could be broken by repeated driving.

Further, since only the valve body 14 and the valve shaft 15 are made of a ceramic material, the casing 1 is not provided due to a difference in thermal expansion.
There is a possibility that the clearance between the valve body 7 and the valve body 14 becomes large, and the sealing performance when fully closed is significantly reduced.

[0007]

The object of the present invention is to provide a ceramic control valve for ventilation.
The temperature is 1200 ° C., the pressure is 5 kg / cm ² , and the flow rate is 150 m / h, as in a blower tube such as a blast furnace hot air stove, a heat recovery tube such as an industrial heating furnace or a tunnel kiln, and a tuyere of a steelmaking blast furnace.
Controlling the flow rate of compressed air or hot air with high temperature, high pressure and high flow rate of up to 2 seconds, ceramic pressure control valve reduces pressure loss of gas flow and improves strength and sealing performance of integrated control valve itself The purpose of this is to smoothly operate the opening and closing of the control valve.

[0008]

The ceramic blow control valve of the present invention comprises three parts, a housing, a butterfly valve and a shaft, which are non-oxide ceramics represented by a silicon nitride sintered body. A ceramic shaft having a cutout surface rotatably supported by two shaft support holes formed in an annular ceramic housing and an elliptical ceramic having a groove on one of the surfaces. Butterfly valve made of metallic silicon (Si) in an annular ceramic housing with a notch and groove fitted
And the like, and the inside of the housing is rotated so that the outer curved surface of the butterfly valve contacts the inner wall surface of the housing,
It is characterized by being arranged to open and close apart.

[0009]

A control valve for air blowing is formed of a non-oxide ceramic represented by a silicon nitride sintered body, and a notch provided on a shaft is fitted to a groove formed on an elliptical butterfly valve. Since it is bonded and integrated with metal silicon (Si), etc., the effective cross-sectional area serving as a gas passage when fully opened is increased, pressure loss is reduced, and the elliptical butterfly valve is opened and closed by two shaft support holes. Therefore, the opening / closing operation is smooth without excessive stress, and the control valve itself has sufficient mechanical strength.

[0010]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of a control valve for blowing air of the present invention. FIG. 1 is a front sectional view in which a ceramic blowing control valve according to one embodiment of the present invention is applied to a high-temperature gas blowing control valve in a duct of an industrial heating furnace, and FIG. It is a side sectional view of the control valve for ventilation.

1 and 2, reference numeral 1 designates a ceramic housing 2 made of a silicon nitride sintered body, a ceramic shaft 3 similar to the above, and a ceramic blow control 4 also made of a ceramic butterfly valve 4. It is a valve.

The ceramic ventilation control valve 1 comprises a ceramic shaft 3 having a notched surface 7 as shown in FIG. 3 rotatably supported by shaft support holes 5 and 6 provided in a ceramic housing 2. An elliptical ceramic butterfly valve 4 provided with a groove 8 as shown in FIG. 4 and fitted into a cutout surface 7 of a ceramic shaft 3 is combined with a ceramic housing 2 as shown in FIG. Insert a thin plate of silicon wafer between the surfaces and fix it with a jig,
The ceramic shaft 3 and the ceramic butterfly valve 4 are joined and integrated by heating in a vacuum furnace to a temperature equal to or higher than the melting point of metallic silicon under vacuum.

Metallic silicon as a bonding agent is 9
As long as the paste has a purity of 9.9% or more, a paste prepared by kneading fine metal silicon powder and an organic solvent may be applied to one of the contact surfaces and used. .

The bonding temperature is set at a melting point of metal silicon of 1
Above 410 ° C, the silicon nitride sintered body does not decompose15
Any temperature may be used as long as it is 50 ° C. or less,
It is preferable that the temperature be higher than or equal to 1500C and lower than or equal to 1500C.

Further, the bonding atmosphere is a vacuum of 1 × 10 ^-1 mmHg or more, more preferably, an oxygen partial pressure of 1 × 10 ^-2 mmHg.
g or less, and is preferably replaced with argon (Ar) gas.

Also, the ratio of the outer diameter 11 to the difference between the inner diameter 9 of the ceramic housing of the ceramic blow control valve 1 and the outer diameter 11 formed by the outer peripheral surface 10 of the ceramic butterfly valve 4 is less than 0.03%. In this case, a slight difference in thermal expansion between the ceramic butterfly valve 4 and the ceramic housing 2 generated during operation at a high temperature causes the ceramic butterfly valve 4 to thermally expand and its rotation becomes difficult.
%, The sealability is sharply reduced. Therefore, the ratio is specified to be 0.03 to 3%, more preferably 0.1 to 3%.
The range is from 03 to 2%.

On the other hand, the ratio of the ceramic shaft outer diameter 12 to the difference between the ceramic shaft outer diameter 12 supported by the shaft support holes 5 and 6 provided in the ceramic housing 2 and the shaft support hole inner diameter 13 is 0. If it is less than 05%, the ceramic shaft 3 is thermally expanded due to a slight difference in thermal expansion between the inner diameter 13 of the shaft support hole and the outer diameter 12 of the ceramic shaft generated at the time of operation at a high temperature, and the ceramic shaft 3 cannot rotate. If it exceeds, the amount of gas leakage increases more rapidly than the gap between the shaft support holes 5 and 6, so that 0.0
It is specified to be 5 to 5%, more preferably in the range of 0.05 to 2%.

In evaluating the ceramic ventilation control valve of the present invention, first, silicon nitride (Si ₃ N ₄ ) powder was added with a sintering aid such as yttria (Y ₂ O ₃ ) and fired. Various types of ceramic housings made of high-quality sintered bodies with an inner diameter of about 150 mm, ceramic shafts with different outer diameters, and ceramic butterfly valves with different outer diameters formed by curved outer surfaces are used as semiconductor components. Using a high-purity silicon wafer-thin plate as a bonding agent and heating in a vacuum furnace at a temperature of 1475 ° C. for 30 minutes under a vacuum of 1 × 10 ⁻³ mmHg, the ceramic shaft 3 and the ceramic butterfly valve 4 are bonded and integrated to form a ceramic. A control valve for air blowing was manufactured.

The thus obtained evaluation blow control valve made of ceramic was set in a duct of an industrial heating furnace, and
The valve was opened and closed in hot air at 000 ° C. to evaluate whether or not it could be turned and the sealability.

As a result, if the ratio of the outer diameter to the difference between the inner diameter of the ceramic housing and the outer diameter formed by the outer curved surface of the ceramic butterfly valve is less than 0.03%, it is considered that the ratio is due to thermal expansion. When a malfunction is recognized and the ratio of the outer diameter of the ceramic shaft to the difference between the inner diameter of the shaft support hole and the outer diameter of the ceramic shaft supported by the shaft support hole is less than 0.05%, the same as described above. It became impossible to rotate.

In addition to the above, in the conventional ceramic valve (Japanese Patent Laid-Open No. 57-161372), rotation could not be performed due to an increase in driving resistance when the valve was opened and closed several hundred times or less.
No abnormality was observed in the ceramic ventilation control valve of the present invention even after opening and closing 200,000 times.

Next, the ratio of the outer diameter of the ceramic shaft to the difference between the outer diameter of the shaft and the shaft of the ceramic shaft is set to 0.4%, and the inner diameter of the ceramic housing and the outer peripheral curved surface of the ceramic butterfly valve are formed. A ceramic blower control valve in which the ratio of the outer diameter to the outer diameter is set variously is fixed via a gasket in a pipe directly connecting the blower and the gas flow meter, and the blower side is at room temperature. The air was flowed while adjusting the blower so that the fluid pressure of 2 kg / cm ² became ² kg / cm ² , the butterfly valve was brought into contact with the inner wall of the housing and fixed in a closed state, and the amount of leakage was measured.

As a result, when the ratio of the outer diameter to the difference between the inner diameter of the ceramic housing and the outer diameter formed by the outer peripheral curved surface of the ceramic butterfly valve is up to 3%, the leakage amount is 150%.
1 / min, but when 3% is exceeded, the amount of leakage increases rapidly. At 4%, the amount of leakage is about 200 l / min.
It reached as high as 00 l / min.

On the other hand, the ratio of the outer diameter to the difference between the inner diameter of the ceramic housing and the outer diameter formed by the outer curved surface of the ceramic butterfly valve is 0.4%. When the ratio of the outer diameter of the ceramic shaft to the difference of
If the ratio is up to 5%, it is about 10 l / min, but if it exceeds 5%, the amount of leakage increases rapidly.
It became clear that it reached about 45 l / min at 5 l / min and 7%.

Next, the following joint strength after heat history is supported by the ceramic blower control valve for supporting the ceramic shaft, and the butterfly valve is pushed out from the notch of the shaft. And the load when peeled off was measured and evaluated.

First, the ceramic blow control valve is
When the temperature of −40 ° C. and 300 ° C. is alternately applied up to 200 cycles, the average of the total load before the heat history is 103 kgf, whereas the average after 100 cycles is 102 kgf, and the average after 200 cycles is 108 kgf, When the cooling and heating cycle at 100 ° C. and 1000 ° C. is applied up to 2500 cycles, the average of all loads before the heat history is 103 k.
gf, whereas after 1000 cycles an average of 114
After 2,500 cycles of kgf, the average was 109 kgf, and it was confirmed that there was no deterioration in the strength of the joint in any case.

Further, even in a high-temperature storage test in which the substrate is left in an atmosphere at 1000 ° C. for 1000 hours, the peeling load of the bonded portion was 103 kgf on average before the thermal history and 105 kgf on average after the thermal history. It was confirmed that the strength of the joint did not deteriorate.

[0028]

According to the ceramic blower control valve of the present invention, the housing, the shaft and the butterfly valve are made of a non-oxide ceramic such as a silicon nitride sintered body having a small thermal expansion. The valve can be closed by directly contacting the outer curved surface of the butterfly valve with the inner wall of the housing, improving the sealing performance and reducing the amount of gas leakage regardless of the temperature. An extremely useful high-temperature, high-pressure, high-speed control valve for ceramic blowers that controls the flow rate of high-temperature, high-pressure, high-velocity compressed air and hot air that can precisely control the flow rate, does not seize the housing and the butterfly valve, and does not break the shaft even under high pressure. Is obtained.

[Brief description of the drawings]

FIG. 1 is a front sectional view in which a ceramic blowing control valve according to one embodiment of the present invention is applied to a high-temperature gas blowing control valve in a duct of an industrial heating furnace.

FIG. 2 is a side cross-sectional view of the ceramic blower control valve of FIG. 1 when fully closed.

FIG. 3 is a perspective view of a ceramic shaft that constitutes the ceramic ventilation control valve of FIG. 1;

FIG. 4 is a perspective view of a ceramic butterfly valve constituting the ceramic blow control valve of FIG. 1;

FIG. 5 is a vertical sectional view of a conventional high-temperature butterfly valve when fully closed.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Ceramic control valve for ventilation 2 Ceramic housing 3 Ceramic shaft 4 Ceramic butterfly valve 5, 6 Shaft support hole 7 Notch surface 8 Groove

Claims (1)

(57) [Claims] An elliptical ceramic butterfly valve having a groove on one of its surfaces and a ceramic shaft having a notched surface fitted into the groove of the butterfly valve are made of metal.
Joined and integrated using silicon, made of an annular ceramic
Use the two shaft support holes provided in the housing to
A ceramic blower control valve wherein a Mick shaft is rotatably supported .