JPH0518558Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a piping joint for transferring high-temperature liquids such as molten metal, and particularly to a piping joint for transferring high-temperature liquids using ceramic pipes.

[Prior Art] In metallurgy, casting, and other fields that handle molten metal, piping for transporting the molten metal from a melting furnace, etc. is required to have heat resistance that can withstand high temperatures higher than the melting point of the molten metal being transported. Furthermore, piping for transporting highly corrosive molten metals such as aluminum and zinc is further required to have corrosion resistance. Conventionally, due to such requirements, ceramic materials have been used for the above-mentioned transfer piping, but these ceramics, however, have the drawback of lacking elasticity and being extremely brittle.

On the other hand, technology related to ceramic materials has improved significantly in recent years, and silicon nitride (Si ₃ N ₄ ) ceramics and silicon carbide (SiC) ceramics, which have excellent high-temperature strength characteristics and high-temperature corrosion resistance, have been used to make cylindrical tubes. Formed structures are now being manufactured and used as piping for transporting molten metal. However, such ceramic tubes are still considerably inferior in strength and flexibility compared to metal tubes, and for example, it is not possible to directly connect a furnace to a furnace using the ceramic tube, and if you are forced to do so, the heat Expansion will cause damage.

Furthermore, in order to ensure heat resistance, special adhesives with high heat resistance are conventionally used to connect the ceramic tubes, and various bonding methods corresponding to these adhesives have been proposed. For example, there are a method using an inorganic adhesive, a method using an oxide as a solder, a method in which the solder is placed between the members to be joined and heat treatment, and a method using a special metal as the solder instead of the oxide. There is also a method of sealing the sliding part between ceramic tubes or the rotating contact part using a sealing material. is used. Furthermore, according to Utility Model Publication No. 62-8474, for example, there is also known a method in which the ends of ceramic tubes are connected with bolts without using adhesive, and this connection is tightened with a spring. It is being

[Problems to be solved by the invention] However, according to the above-mentioned conventional technology, when adhesives or solders are used, bonding takes a long time, high-temperature heating is required, or special connection equipment is required. Ceramic connections require special techniques, and there are also problems with the reliability of the connection. Additionally, it is extremely difficult to separate ceramic pipes that are firmly connected using the method described above once they have been connected, which makes it extremely difficult to separate them once they have been connected. If this occurs, it is necessary to replace all the piping before and after it, which is not economical. Furthermore, ceramics lack flexibility and cannot relieve thermal stress by bending the tube itself, unlike metal tubes, and this thermal stress cannot be alleviated with adhesives.

In addition, in the method using a heat-resistant sheet, the alumina-silica ceramic fiber causes a chemical reaction between aluminum and silica (SiO ₂ ) against molten aluminum: 3SiO ₂ + 4Al→2Al ₂ O ₃ + 3Si. , it gradually turns black, metal silicon is liberated, it becomes hard and brittle, and the sealing effect is lost. Furthermore, when the ceramic fibers in the seal portion of the sliding surface or rotating surface are rubbed, the fibers become frayed, and the sealing effect gradually decreases.

Although the method of connecting ceramic pipes with bolts and tightening this connection with a spring, as in the above-mentioned Utility Model Publication No. 62-8474, is an effective method as a joint for ceramic pipes, the above-mentioned silicon nitride So-called fine ceramics such as (Si ₃ N ₄ ) ceramics and silicon carbide (SiC) ceramics are difficult to mold into somewhat complex shapes, and problems remain in their performance and reliability.

Therefore, in view of the problems in the above-mentioned conventional technology, the present invention allows easy connection,
To provide a piping joint for transferring high-temperature liquid that does not generate thermal stress and has excellent sealing performance despite sliding and rotation of a ceramic pipe.

[Means for Solving the Problems] The object of the present invention is to fit the ends of a pair of pipes to be joined from both ends of a sleeve and butt them together at a joint of a pipe for transferring high-temperature liquid; A high-temperature liquid characterized in that a groove is formed around the entire circumference between the sleeve and the end of the pipe, and a molten salt having a melting point lower than the melting point of the liquid to be transferred is sealed in the groove. This is accomplished by means of a transfer pipe fitting.

[Function] That is, according to the piping joint for transferring high-temperature liquid described above, the gap between the sleeve and the piping is filled with high-viscosity molten salt, thereby sealing high-temperature liquid such as molten metal, and Since the inner surface of the sleeve and the outer surface of the pipe are in contact with each other through the thin film of the high-viscosity molten salt, no thermal stress is generated even if the pipe stretches in the axial direction due to thermal expansion, and the pipe It is also easy to connect and disconnect.

[Embodiments] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

In the figure, the piping joint for transferring high-temperature liquid according to the present invention consists of a pair of ceramic fittings 1, 1 to be connected, which are manufactured from ceramic such as silicon nitride (Si ₃ N ₄ ) or silicon carbide (SiC). The ends of the sleeve 2 are inserted from both ends of a sleeve 2 made of ceramic such as silicon nitride (Si ₃ N ₄ ) or silicon carbide (SiC), and are butted together at approximately the center. A groove 3 is provided around the entire circumference of the ceramic tubes 1, 1 near the ends thereof, forming a so-called molten salt reservoir 4, as described in detail later. Molten salt is filled to seal between the ends of the ceramic tubes 1 and the sleeve 2. That is, the gap between the sleeve 2 and the pipes 1, 1 is filled with high-viscosity molten salt, thereby sealing high-temperature liquid such as molten metal flowing through the space, and sealing the space between the inner surface of the sleeve and the pipes. It is bonded to the outer surface of the metal via the thin film of the high viscosity molten salt.

Further, the ceramic sleeve 2 is provided with holes 5, 5 for replenishing molten salt that communicate with the molten salt reservoir 4, and these holes 5, 5 for replenishing the molten salt are provided with metal pipes 6 for replenishing the molten salt. , 6 are inserted. As is clear from the figure, these metal fittings 6, 6 for replenishing molten salt are attached to the upper side of the ceramic sleeve 2, and the metal fittings 6, 6 for replenishing molten salt are attached to the upper side of the ceramic sleeve 2.
6 to prevent the molten salt from spilling out. Further, so-called stoppers 7, 7 are formed on the outer periphery of the ceramic tubes 1, 1 so as to protrude over the entire circumference of the ceramic tubes in order to keep the ceramic sleeve 2 within a predetermined range. .

Furthermore, a heater is installed around the outer periphery of the ceramic tubes 1, 1 and the ceramic sleeve 2 to prevent the molten metal such as aluminum or zinc passing through the inside from solidifying, that is, to heat it to the same temperature as the molten metal. 8 (for example, an electric heater) is wound around it. The heater 8 is wound so that the temperature of the sleeve 2 can be raised somewhat faster than that of the ceramic tubes 1, 1. The outer peripheries of the ceramic tubes 1, 1 and the ceramic sleeve 2 are further covered with a heat insulating material 9 having a substantially constant thickness to prevent heat radiation.

In transferring the molten metal through the pipe joint, the granular salt with a low melting point is passed through the molten salt supply holes 5, 5 from the molten salt supply metal pipes 6, 6. The salt is placed in the molten salt reservoirs 4, 4, and as the temperature rises, the shortage is replenished so that at least the molten salt reservoirs 4, 4 are filled with the molten salt of low melting point. This confirmation can be easily performed, for example, by inserting a wire or the like into the molten salt supply metal pipe 6 and checking how much molten salt is attached to the tip of the wire. .

In the embodiments described above, a particular example of the material of the molten salt is a mixture with a molar percentage ratio of KCl:MgCl:NaCl=20:50:30. The melting point of this molten salt is 396°C. Furthermore, it is also possible to use this molten salt by adding some borax (Na ₂ B ₄ O ₇ ). This molten salt is preferably a molten salt with a low melting point that is below the melting point of the metal to be transferred, and is stable and non-toxic without reacting with ceramics.
Furthermore, it is desirable that the viscosity during operation be high. Therefore, the above-mentioned molten salt is not limited to the above-mentioned examples, but can also be used, for example, as molten flux used for hot plating of metals, molten salt baths used for electrolytic refining of metals, and even salt bath furnaces for metal heat treatment. It can be selected from among the salt baths of various compositions used. Further, it is desirable that the molten salt be one that melts at as low a temperature as possible. This is because once the granular salt is melted and the temperature of the joint is lowered after its use, the molten salt solidifies with the molten salt reservoir 4 completely filled. Therefore, the temperature of the joint is increased in order to use it again, but at this time, unless the solidified salt has a low melting point, the salt completely filled in the molten salt reservoir 4 will not melt quickly. First, this is because the elongation of the pipe 1 in the axial direction due to the rise in temperature cannot be absorbed, and instead, excessive thermal stress is applied to the pipe 1, causing damage.

The material of the ceramic tube 1 must be selected depending on the type of molten metal to be passed through the tube, and the material of the sleeve 2 is also the same as that of the ceramic tube 1. for example,
For highly corrosive molten metals such as aluminum and zinc, silicon nitride (Si ₃ N ₄ ) and Sialon are selected. It is also possible to coat the inner surface of a stainless steel pipe with the ceramic and use it as the pipe 1 or the sleeve 2.

[Effects of the invention] As is clear from the above explanation, according to the invention, the gap between the pipe and the sleeve is filled with high viscosity molten salt, so that the pipe can slide freely. It is also possible to withstand rotation, and even if the piping is stretched in the axial direction due to thermal expansion, no thermal stress is generated, and damage to the piping and the sleeve can be prevented. In addition, the structure of the connection part is simplified, making it easy to manufacture, and connecting and disconnecting piping can be done quickly and easily, thereby simplifying piping and repair work. It is possible to provide a piping joint for transferring high-temperature liquid.

[Brief explanation of drawings]

The drawing is a perspective view, partially in cross section, showing the structure of a piping joint for transferring high temperature liquid, which is an embodiment of the present invention. 1...Ceramic tube, 2...Sleeve, 3...
Groove, 4... Molten salt reservoir, 5... Molten salt supply hole,
6... Metal pipe for supplying molten salt, 7... Stopper,
8... Heater, 9... Insulating material.

Claims (1)

[Scope of utility model registration request] At the joints of piping that transfers high-temperature liquids,
The ends of the pair of pipes to be joined are inserted into the sleeve from both ends and butted together, and a groove is formed between the sleeve and the ends of the pipes along their entire circumference, so that the liquid to be transferred can be A piping joint for transferring high-temperature liquid, characterized in that a molten salt having a melting point lower than the melting point is sealed in the groove.