JPS6363797B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a tubular component made of ceramic material. In general, ceramic materials have excellent heat resistance, corrosion resistance, wear resistance, and electrical insulation properties, and are used in various parts. For example, in high-temperature steam equipment, an electric heater is housed in a flow pipe, and the electric heater is energized to generate heat, and water is flowed through the flow pipe and heated by the electric heater to generate high-temperature steam. In this device, the flow pipe is made of ceramic material because it is required to have heat resistance and electrical insulation properties. However, ceramic materials are susceptible to thermal shock, so if, for example, low-temperature water flows into the flow pipe in the above-mentioned equipment, the temperature will change rapidly, and the thermal shock will cause the ceramic flow pipe to become damaged. This caused a crack and caused the flow pipe to break. For this reason, conventionally, the inner tube member was formed of ceramic material, and the outer periphery of this inner tube member was
A reinforcing member made of SUS316 austenitic stainless steel is tightly fitted by shrink fitting, etc., and compressive force is applied in advance to the inner tube member made of ceramic material to prevent cracks from occurring in the inner tube member. However, even if a crack were to occur, the structure was designed to prevent the crack from progressing and to prevent damage. However, the coefficient of thermal expansion of ceramic materials (Al ₂ O ₃ ...99%, SiO ₂ and others ...1%) is, for example, 6.8 × 10 ^-6 /°C around 306°C, whereas the SUS316 austenitic stainless steel mentioned above The coefficient of thermal expansion of steel is 16.2×10 ^-6 /°C, which is greater than that of ceramic materials. Therefore, the thermal expansion of the reinforcing member caused by the rise in temperature becomes larger than the thermal expansion of the inner pipe member, and as the temperature rises, the tightening of the inner pipe member by the reinforcing member becomes weaker. When a certain temperature is reached, the tightening of the inner tube member becomes zero, and if the temperature rises any further, a gap is created between the inner surface of the reinforcing member and the outer circumferential surface of the inner tube member, and the reinforcing member no longer serves as a reinforcement. . In addition, when a pressure detection hole is formed in such a flow pipe, if a gap is created between the inner pipe member and the reinforcing member as described above, the internal fluid will pass through this gap to the outside. This may cause problems such as leakage. For this reason,
There was a limit to the operating temperature of such a structure. To increase the upper limit of this operating temperature, increase the dimensional difference between the outer diameter of the inner tube member and the inner diameter of the reinforcing member,
It is sufficient to increase the initial compressive force of the inner tube member, but if the initial compressive force of the inner tube member is increased, the tensile stress of the reinforcing member increases accordingly, and this tensile stress form a member
Once the plastic deformation range of SUS316 austenitic stainless steel is reached, it is no longer possible to increase the clamping force of the inner tube member any further, and there is a limit to the compressive force that can be applied to the inner tube member, so the upper limit of the operating temperature cannot be set too high. There was a problem that made it impossible to do so. The present invention has been made based on the above circumstances, and its object is to obtain a tubular component using a ceramic material that can increase the upper limit of the operating temperature. The present invention will be described below with reference to an embodiment shown in the drawings. In this embodiment, the tubular component of the present invention is used as a flow pipe in a heating section of a high-temperature steam facility. First, the overall structure of this facility will be explained. In the figure , 1 is a heat generating part, and 2 is its outer cylinder. A flow pipe 3 is provided inside this outer cylinder 2.
A tubular energized heating element 4 is housed within the flow pipe 3 as a heat generation source. Both ends of this energizing heating element 4 are connected to a power supply device 5, and a current is passed from this power supply device 5 to the energizing heating element 4, and this energizing heating element 4 generates heat while the above-mentioned flow pipe 3
Water is supplied from the lower end of the flow pipe 3, and the supplied water is heated by the energized heating element 4 while rising inside the flow pipe 3, and is configured to boil and turn into high-temperature steam. This steam is configured to be sent into the steam drum 6 from the upper end of the flow pipe 3. A spargeer 7 is provided in the upper part of the steam drum 6, and low-temperature water is sprayed from the spargeer 7, and the steam sent into the steam drum 6 is condensed into water. There is. The water accumulated in the steam drum 6 is sent to a heat exchanger 9 by a pump 8 to be cooled, and is then supplied to the spargeer 7 via a flow rate regulating valve 10. Also, the water accumulated in the steam drum 6 is pumped through a flow rate regulating valve 12 by a pump 11.
It is configured to be supplied to the lower end of the flow pipe 3 of the heat generating section 1 via the cooling pipe 13. Note that 14 is a pressurizer that pressurizes the inside of the steam drum 6 to a constant pressure. The flow pipe 3 of the heat generating section 1 is constructed as shown in FIGS. 2 and 3. That is, the flow pipe 3 is constructed by axially arranging a plurality of short pipe members 15 each having a relatively short cylindrical shape. And these short tube members 15
...is ceramic material Al ₂ O ₃ ...99%, SiO ₂ and others ...1%
It is composed of cylindrical inner tube members 15a... and cylindrical reinforcing members 15b fitted to the outer periphery of these inner tube members 15a... These reinforcing members 15b are made of a metal material having a coefficient of thermal expansion similar to that of the ceramic material of the inner tube members 15a, such as a zirconium alloy such as Zircaloy, or a titanium alloy. The inner diameter of these reinforcing members 15b... is the inner diameter of the inner tube member 15a.
It is formed to have a smaller diameter than the outer diameter of the inner tube members 15a, and is tightly fitted to the outer periphery of the inner tube members 15a by shrink fitting or the like, and applies a predetermined compressive force to these inner tube members 15a.
The shrink fit should be done as follows. If the temperature of the outer reinforcing member 15b with a diameter of 20 mm is raised to 820° C., the inner diameter of the reinforcing member 15b will increase by approximately 1 mm due to thermal expansion. In this state, the reinforcing member 15b is attached to the inner tube member 15a made of ceramic at room temperature (20° C.). Furthermore, annular protrusions 16 and recesses 17 that fit into each other are formed on both end surfaces of these inner tube members 15a, and these protrusions 16 and recesses 17 fit into each other and these short It is configured to hold the tube members 15 concentrically. In addition, both end surfaces of these inner tube members 15a are finished smoothly so that they come into close contact with each other in a liquid-tight manner, and these short tube members 1
5... is configured to maintain liquid tightness between the parts.
A pressing member 18 is fitted onto the upper end surface of the short tube member 15 at the uppermost end, and this pressing member 18 is urged downward by springs 19 to move the short tube member 15 in the axial direction. It is fixed by pressure. In addition, the inner tube member 15 of the short tube member 15 in the intermediate portion
A pressure detection hole 20 is formed in the peripheral wall portion a. A pressure detection tube 21 is attached to the peripheral wall of the reinforcing member 15b in correspondence with the pressure detection hole 20, and the pressure detection tube 21 is inserted into the short tube member 15 through the pressure detection hole 20. tube 3
It communicates within. And this pressure detection tube 21
is connected to a pressure detector 22, and is configured to be able to detect the pressure inside this flow pipe 3. The portion where this pressure detection tube 21 passes through the outer cylinder 2 is kept sealed by a sealing material 23 or the like. Further, this pressure detection tube 21 has flexibility at least in a portion between the flow tube 3 and the outer cylinder 2, and is configured to allow expansion and contraction of the flow tube 3 in the axial direction due to temperature rise. In one embodiment of the present invention constructed as described above, a current is passed from the power supply device 5 to the energized heating element 4 to cause the energized heating element 4 to generate heat, and water is supplied from the lower end of the flow pipe 3. The supplied water rises in the flow pipe 3 and is heated by the energized heating element 4 to boil, and is sent to the steam drum 6 as steam at a high temperature of about 306°C. The flow pipe 3 through which this water and steam flows is constructed by combining short pipe members 15 using inner pipe members 15a made of ceramic material, so it has sufficient heat resistance and corrosion resistance. Furthermore, since the ceramic material is an electrically insulating material, the current supplied to the current-carrying heating element 4 will not bypass and flow through the flow tube 3. And the inner tube member 15
Reinforcing member 15b fitted to the outer periphery of a...
As mentioned above, since a metal material such as a zirconium alloy such as Zircaloy or a titanium alloy is used, the coefficient of thermal expansion is similar to that of the ceramic material used for the inner tube member 15a.
Sufficient tightening force can be applied to the inner tube member 15a even at a relatively high operating temperature of 306°C.
It is possible to reliably prevent the occurrence of cracks in these inner tube members 15a and the progress of the cracks. That is, the coefficient of thermal expansion of the ceramic material of the inner tube members 15a is β ₁ , the coefficient of thermal expansion of the metal material of the reinforcing members 15b is β ₂ , the outer diameter of the inner tube members 15a at room temperature To° C. is d ₁ , and the reinforcement The inner diameter of the member 15b is d ₂ (d ₁ > d ₂ )
Then, the inner tube member 1 at a certain operating temperature T°C
The outer diameter d ₁ ′ of reinforcing member 5a and the inner diameter d ₂ ′ of reinforcing member 15b are d ₁ ′=d ₁ {1+(T−T ₀ )β ₁ } …(1) d ₂ ′=d ₂ {1+( T−T ₀ ) β ₂ } …(2). At a certain operating temperature T°C, at least the outer periphery of the inner tube member 15a... and the reinforcing member 15b...
In order to prevent _a gap from forming between the _inner surface of Therefore, the inner diameter d ₂ of the reinforcing member 15b at room temperature in such a case is d ₁ {1+(T-T ₀ )β ₁ } = d ₂ {1+(T-T ₀ )β ₂ }...(4 ), so d ₂ =d ₁ 1+(T-T ₀ )β ₁ /1+(T-T ₀ )β ₂ (5). The operating temperature T is T=306°C as in the above embodiment, and the coefficient of thermal expansion β ₁ at 306°C of the ceramic material of the inner tube member 15a is β ₁ =6.8×
10 ^-6 /℃, the outer diameter d ₁ of the inner tube member 15a... is d ₁ = 209
mm, if SUS316 austenitic stainless steel is used as the material of the reinforcing member 15b as in the past, its coefficient of thermal expansion β ₂ at 306°C is β ₂ =16.2×10 ^-6 /°C, so the above (5 ) formula, d ₂ = 208.44mm. Therefore, such an inner tube member 15a
When the reinforcing member 15b is shrink-fitted to the reinforcing member 15b, the strain ε generated in the reinforcing member 15b at room temperature is ε=d ₁ −d ₂ /d ₂ =0.00269 (6). The value of this strain ε is shown in Figure 4.
Stress in SUS316 austenitic stainless steel
When applied to the strain diagram, the stress in this case is approximately 24.6
Kg/mm ² , which exceeds the elastic region and enters the plastic region. Therefore, such a reinforcing member 15b
When the reinforcing member 15b... is shrink-fitted, _the reinforcing member 15b... will be permanently deformed and its inner diameter _d2 will expand due to the permanent deformation. result. For this reason, when such a product is actually manufactured and heated, a gap is created between the outer periphery of the inner tube member 15a and the inner surface of the reinforcing member 15b at about 180° C. as shown in FIG. However, if the reinforcing members 15b are made of a metal material having a coefficient of thermal expansion close to that of the ceramic material used for the inner tube members 15a, as in the above embodiment, for example, Zircaloy
Zr…98%, Sn…1.5%, Fe…0.15%, balance Cr, etc.)
is used, its coefficient of thermal expansion β ₂ at 306°C is β ₂ = 6.3×10 ^-6 /°C, so the above formula (5) and
From equation (6), the strain ε is ε=0.00014, and the longitudinal elastic modulus E of Zircaloy is E=7.99×10 ³ Kg/mm ² , so the stress in this case is 1.1 Kg/mm ² , which is well within the elastic region. Therefore, the above-mentioned problems do not occur, and a sufficient tightening force can be applied to the inner tube members 15a even at high temperatures. In addition, when titanium alloy is used, its coefficient of thermal expansion is β ₂ = _9.45 ×
10 ^-6 /℃, and the stress in this case is 11.7Kg/mm ² , which is well within the elastic range, so even at high temperatures (306℃) like in the case of Zircaloy, the inner tube member 15a has sufficient strength. Can provide tightening force. As for the metal material used for the reinforcing members 15b, various materials having a coefficient of thermal expansion close to that of the ceramic material can be used depending on the type of ceramic material used for the inner tube members 15a, the operating temperature, etc. However, the coefficient of thermal expansion of ceramic materials is generally close to the above value, and many of the zirconium alloys and titanium alloys mentioned above have been developed as structural materials with excellent mechanical properties, and have excellent corrosion resistance. In practice, it is preferable to use a zirconium alloy or a titanium alloy because of their superior properties. It should be noted that the present invention is not limited to the above-mentioned embodiment, but can be applied to general tubular parts through which fluid flows and which are used at high temperatures. As described above, in the present invention, a reinforcing member made of a metal material having a coefficient of thermal expansion close to that of the ceramic material is tightly fitted to the outer periphery of an inner tube member made of a ceramic material. This applies compressive force to the Therefore, the advantages of ceramic materials such as heat resistance, corrosion resistance, abrasion resistance, and electrical insulation properties are obtained, and since compressive force is applied to the inner tube member made of ceramic material, this inner tube may be damaged by thermal shock, etc. This prevents cracks from occurring in the member, and the coefficient of thermal expansion of the metal material used for the reinforcing member is close to that of the ceramic material, so the inner tube member can be sufficiently tightened even at high temperatures. Its effects are great, such as being able to apply force and ensure sufficient strength.

[Brief explanation of drawings]

Figures 1 to 3 show one embodiment of the present invention, with Figure 1 being a schematic diagram of the entire system, Figure 2 being a vertical sectional view of the heating section, and Figure 3 taken along the line - in Figure 2. FIG. Figure 4 is a stress-strain diagram of SUS316 austenitic stainless steel used to explain its characteristics at high temperatures, and Figure 5 is the characteristics of the gap between the inner tube member and reinforcing member as the temperature increases. It is a diagram. 1 ...Heating part, 3...Flow pipe, 4...Electric heating element, 1
5...Short pipe member (tubular part), 15a...Inner pipe member,
15b...Reinforcement member.

Claims (1)

[Scope of Claims] 1. An inner tube member formed of a short cylindrical ceramic material, which is tightly fitted to the outer periphery of the side of the inner tube member by shrink fit, and which is heated to the above ceramic material at around 306°C. A tubular part consisting of a cylinder made of a zirconium alloy with a similar coefficient of expansion, which maintains the above-mentioned tightness even at temperatures around 306°C, and which can be formed into a long cylindrical shape by laminating these members. 2. The tubular component according to claim 1, wherein the inner side of the inner tube member is a quadrangular prism-shaped hole. 3. The tubular component according to claim 1 or 2, wherein a recess for stacking positioning is formed in the end face of the inner tube member.