JPH0718667B2 - Ceramic heat exchanger - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a heat exchanger in which both ends of a ceramic heat transfer tube are supported by a pair of tube plates that are arranged to face each other, and particularly, a connection between the ceramic heat transfer tube and the tube plate. Regarding the improvement of the structure.

"Prior art and its problems" Most of the multi-tube heat exchangers currently used have heat transfer tubes, tube plates, and other structures made of metal. Welding, pipe expansion, etc.
There was also no leakage between the heated and heated fluids. However, the heat resistance temperature of metal heat transfer tubes is limited,
Heat exchange of fluids above 800-900 ° C was impossible.

Therefore, attempts have been made to use a ceramic tube as the heat transfer tube. However, unlike metal, ceramic does not deform when applied with an external force and ruptures.Therefore, relative displacement due to component dimensional error and thermal expansion difference during use at the connection between the heat transfer tube and tube sheet. Had to try to tolerate.

Conventionally, as a connection structure between a ceramic heat transfer tube and a tube plate, for example, a structure shown in FIG. 10 has been adopted. That is, the end of the ceramic heat transfer tube 11 is inserted into the fluid passage hole of the metal tube plate 12. The tube sheet 12 has a cylindrical portion 13 surrounding the heat transfer tube 11. A pair of heat-resistant seal rings 14, 14 is arranged between the outer circumference of the heat transfer tube 11 and the inner circumference of the cylindrical portion 13, and seal sand 15 is filled between the seal rings 14, 14. Further, the outer seal ring 14 is attached to the pressing lid 16
Is pressed by. In addition, 17 is a heat insulating material. Therefore, the heat transfer tube 11 is supported via the sealing sand 15 so that it can be displaced relative to the tube sheet 12.

However, in the above connection structure, the heat transfer tube 11 and the tube sheet 12
The fluid leakage cannot be completely prevented at the seal portion between and, and for example, if the pressure difference between the heating fluid and the fluid to be heated becomes 1 atm or more, the fluid leakage cannot be ignored. Therefore, it cannot be used for a heat exchanger that cannot tolerate fluid leakage or a high-pressure or high-differential pressure heat exchanger.

[Object of the Invention] An object of the present invention is to solve the above-mentioned problems of the prior art, to enable relative displacement at the connection portion between the ceramic heat transfer tube and the tube sheet, and to prevent fluid leakage at the connection portion. The present invention provides a ceramic heat exchanger.

"Structure of the Invention" That is, one of the present invention is a ceramic heat exchanger in which both ends of a ceramic heat transfer tube are supported by a pair of metal tube plates that are arranged to face each other, and the fluid of one of the tube plates is A holding ring is arranged corresponding to the flow hole, and the holding ring is pressed against one end face of the ceramic heat transfer tube by a pressurizing means provided between the holding ring and the tube sheet. The other end surface of the ceramic heat transfer tube is pressed against and supported by the receiving surface of the other tube sheet by a force, and both end surfaces of the ceramic heat transfer tube, and the contact surfaces of the holding ring and the receiving surface, It is characterized by being smoothed so that the surface roughness is 6.3 S or less.

Another aspect of the present invention is a ceramic heat exchanger in which both ends of a ceramic heat transfer tube are supported by a pair of metal tube plates that are arranged to face each other, and the ceramic heat exchanger corresponds to the fluid passage hole of one of the tube plates. And a holding ring is arranged, and the holding ring is pressed against one end face of the ceramic heat transfer tube through a connecting ring by a pressurizing means provided between the holding ring and the tube sheet. The other end surface of the ceramic heat transfer tube is urged by the urging force to the receiving surface of the other tube plate, and is pressed against and supported via the connection ring,
The respective contact surfaces of the ceramic heat transfer tube, the connection ring, the holding ring and the receiving surface have surface roughness.
It is characterized in that it is smoothed so that it is 6.3 S or less.

Therefore, the relative displacement in the axial direction of the heat transfer tube due to the dimensional error and the difference in the coefficient of thermal expansion can be absorbed by the movement of the holding ring. Also, the relative displacement of the heat transfer tube in the radial direction is
It can also be absorbed by sliding the contact surface on the receiving surface of the retaining ring and the other tube sheet. Furthermore, since both end surfaces of the heat transfer tube are pressed against the corresponding contact surfaces by the pressurizing means, fluid leakage is also prevented.

According to one aspect of the present invention, both end surfaces of the ceramic heat transfer tube are directly pressed against the holding ring and the receiving surface, and the contact surfaces thereof are smoothed. In this way, by smoothing the contact surface, the contact surface can be slid easily, so that it is possible to easily absorb the relative displacement of the heat transfer tube in the radial direction, and the adhesion is improved so that the fluid Leakage is also more reliably prevented. The smoothing treatment here means that the surface roughness of each contact surface is 6.3 S or less, preferably
It means that it is finished to 0.8S or less and that it is shaped so as to be in close contact with the entire circumference of the end face.

According to another aspect of the present invention, both end surfaces of the ceramic heat transfer tube are pressed against the holding ring and the receiving surface via connection rings, respectively. Thus, by interposing the connecting ring, when the ceramic heat transfer tube is formed into a cylindrical shape that can be easily molded, the end portion can be changed into a desired shape by the connecting ring. In addition,
The retaining ring is usually made of metal, but the connecting ring must be made of ceramic. In other words, the connection ring meets the conditions that it has high heat resistance because it comes into contact with the heat transfer tube that becomes hot and becomes hot, and that it has low thermal conductivity so as not to transfer the heat of the heat transfer tube to the retaining ring. Because it must be.

The connecting ring may be disc-shaped like the retaining ring, but according to a further preferred embodiment of the invention the connecting ring has a tapered inner diameter in cross section. By thus forming the connecting ring with a tapered inner diameter, it is possible to dispose a cylindrical heat insulating material or the like on the inner circumference of the connecting ring without reducing the flow passage cross-sectional area, and thereby the outer ring is positioned on the outer circumference. Metal parts such as the retaining ring can be protected from the high temperature fluid flowing inside the heat transfer tube.

Even when the connection ring is used, it is necessary that the contact surfaces of the ceramic heat transfer tube, the connection ring, the holding ring and the receiving surface are smoothed for the same reason as above.

According to a further preferred aspect of the present invention, a tubular body extending in the axial direction of the ceramic heat transfer tube is formed in the holding ring, and the tubular body is in sliding contact with the inner circumference of the through hole of one of the tube sheets. According to this, the holding ring can be supported so as to be axially displaceable with respect to the tube sheet, and the airtightness between the holding ring and the tube sheet can be held by the tubular body.

According to a further preferred aspect of the present invention, the pressing means comprises a spring or a hydraulic cylinder. In this case, various springs such as coil springs and disc springs can be used.

According to a still further preferred aspect of the present invention, the tube sheet has a water cooling structure, and the retaining ring and the pressurizing means are arranged in a portion surrounded by the water cooling structure. According to this, since the holding ring and the pressurizing means are radiatively cooled by the water cooling structure, sufficient heat resistance can be imparted.

As such a ceramic heat transfer tube used in the present invention, it is desirable that the ceramic heat transfer tube have sufficient strength and good thermal conductivity even if the wall thickness is small. Specifically, even if the wall thickness is about 5 to 10 mm, it has a bending strength of, for example, 20 kg / mm ² or more, and a 20 kc
A material having a thermal conductivity of al / m / h / K or more is desirable, and silicon carbide is most preferable as a material that easily satisfies these. On the other hand, it is suitable that the connecting ring is made of silicon nitride or the like having the same strength as above but relatively low thermal conductivity.

In the present invention, the holding ring and the connecting ring may be provided in common to a plurality of ceramic heat transfer tubes, but the ceramic heat transfer tubes have different dimensional accuracy and thermal expansion coefficient for each component due to their material characteristics. Since variations easily occur,
The holding ring and the connection ring are preferably provided for each ceramic heat transfer tube.

"Embodiment of the Invention" FIG. 1 shows almost the entire heat exchanger embodying the present invention. This heat exchanger 21 includes a plurality of ceramic heat transfer tubes.
The heat transfer tube 22 has its both ends supported by a pair of tube plates 23, 24. A flow path 20 of the heating fluid H that crosses the heat transfer tube 22 is formed between the tube plates 23 and 24. Also, the tube sheet 2
The outer sides of 3 and 24 are surrounded by headers 25 and 26, respectively, and a flow path 27 for the fluid to be heated C that flows from one header 26 into the heat transfer tube 22 and flows out to the other header 25 is formed. A water cooling jacket 28 is formed on each of the tube plates 23 and 24, and both ends of the heat transfer tube 22 are supported by a portion surrounded by the water cooling jacket 28. Both ends of the heat transfer tube 22 are expanded, and the end surfaces are smoothed. One end surface of the heat transfer tube 22 is pressed against a receiving surface of the lower surface of the disc-shaped holding ring 29, and the other end surface of the heat transfer tube 22 is pressed against a receiving surface 30 fixedly provided on the tube sheet 24. In this case, retaining ring 29
The receiving surface and the receiving surface 30 of the tube sheet 24 are also smoothed so as to be in close contact with the end surface of the heat transfer tube 22. The inner and outer surfaces of the tube sheets 23 and 24 are covered with a heat insulating material 31, respectively.

2 and 3 show the connecting structure of the retaining ring 29 portion of the heat exchanger 21. A guide rod 32 is erected on the retaining ring 29. A plurality of guide rods 32 (eight in this embodiment) are provided along the peripheral edge of the retaining ring 29. At the inner lower surface of the annular support 33 fixed to the upper surface of the tube plate 23, a tube 34 is provided corresponding to the position of the guide rod 32.
Is provided. The tip of the guide rod 32 is inserted into the cylinder 34. Therefore, the holding ring 29 is movably supported along the axial direction of the heat transfer tube 22 via the guide rod 32. On the outer circumference of the guide rod 32, a spring 36 is arranged between the holding ring 29 and the tip of the cylinder 34, and the spring 36 presses the holding ring 29 against one end surface of the heat transfer tube 22.
By this biasing force, as described above, the other end surface of the heat transfer tube 22 is pressed against the receiving surface 30 of the other tube sheet 24.
An expansion joint 38 is mounted between the holding ring 29 and the support 33 so as to surround the flow hole 37 for the heated fluid C. In addition, a cylindrical heat insulating material 39 forming the peripheral wall of the flow hole 37 is arranged inside the holding ring 29 and the support 33, and the tip of the heat insulating material 39 is tapered and enters the enlarged diameter portion of the heat transfer tube 22.
Incidentally, FIG. 1, FIG. 2, FIG. 3 and FIG.
In FIGS. 6, 7, and 8, the spring 36 is schematically shown by a chain line.

In the above structure, the heating fluid H flows through the flow path 20 and contacts the heat transfer tube 22 to heat the heat transfer tube 22. The fluid to be heated C flows in the flow path 27 from the header 26 to the header 25 through the heat transfer tube 22, and the fluid C to be heated is heat-exchanged and heated when passing through the heat transfer tube 22. It should be noted that the fluid to be heated C can be passed through the flow path 20 and the heating fluid H can be passed through the flow path 27. By the way, since the main body of the heat exchanger 21 and the tube plates 23 and 24 are made of metal, the coefficient of thermal expansion is different from that of the ceramic heat transfer tube 22, and relative displacement occurs due to the difference in coefficient of thermal expansion. The relative displacement of the heat transfer tube 22 in the axial direction is absorbed by the spring 36 expanding and contracting, the holding ring 29 moving in the axial direction, and the expansion joint 38 expanding and contracting accordingly. Further, the radial displacement of the heat transfer tube 22 is absorbed by allowing the expansion joint 38 to have some radial displacement and sliding between the contact surfaces at both end surfaces of the heat transfer tube 22. In this case, since the contact surfaces are all smoothed, sliding is facilitated. Further, since the contact surfaces at both end surfaces of the heat transfer tube 22 are brought into close contact with each other by the smoothing treatment, the fluid leakage at this portion is sufficiently prevented. Further, in this embodiment, since the expansion joint 38 is provided, the airtightness between the retaining ring 29 and the support 33 is also retained. Further, the spring 36 and the expansion joint 38 are made of metal and are expected to be weak against high temperatures, but the water cooling jacket 28 surrounds the outer circumference of the spring 36 and radiation cooling, and the spring 36 and the expansion joint 38 are arranged outside the heat insulating material 39. Therefore, heat damage is prevented.

FIG. 4 shows another embodiment in which the connecting structure of the retaining ring 29 is changed. In this embodiment, the retaining ring 29
The tubular body 40 is erected upward from the inner upper surface of the
It is in sliding contact with the inner circumference of an annular support 41 extending from 23 and forming a through hole. A seal ring 42 made of heat resistant rubber such as silicone rubber is interposed between the tubular body 40 and the support 41. Further, a plurality of guide rods 43 are provided upright on the lower surface of the support 41 in the axial direction, and the lower end of the guide rod 43 is inserted into a hole provided in the peripheral edge of the holding ring 29.
A spring 36 is attached between the holding ring 29 and the support 41 on the outer circumference of the guide rod 43. Therefore, the retaining ring 29 is movable in the axial direction while being guided by the tubular body 40 and the guide rod 43, and the spring
It is pressed against the end surface of the heat transfer tube 22 by 36. Further, between the holding ring 29 and the support 41, since the outer circumference of the heat insulating material 39 is surrounded by the tubular body 40, the airtightness in that portion is maintained.

FIG. 5 shows still another embodiment in which the connecting structure of the retaining ring 29 is changed. In this embodiment, a piston 44 is attached to the tip of a guide rod 32 erected on the retaining ring 29, and the piston 44 is inserted into a cylinder 45 formed in a support 41 of the tube sheet 23. Then, the pressurized fluid is introduced into the cylinder 45 above the piston 44 through the pressurized fluid introduction passage 46. The retaining ring 29
As in FIG. 2, the expansion joint 38 is provided between the cylinder 45 and the cylinder 45. In this embodiment, the piston 44 is pushed by the pressurized fluid introduced into the cylinder 45, and the holding ring 29 is pushed against the end surface of the heat transfer tube 22 via the guide rod 32.

6 and 7 show another embodiment in which the connecting structure of the retaining ring 29 is changed. In this embodiment, both end surfaces of the heat transfer tube 22 are pressed against the holding ring 29 and the receiving surface 30 via the connecting rings 47, respectively. The connecting ring 47 has a tapered inner diameter in cross section, and the ceramic heat transfer tube 22 is provided on the end surface of the connecting ring 47 having the smaller diameter.
One of the end faces is in contact, and the holding ring 29 or the receiving face 30 is in contact with the end face of the connection ring 47 having the larger diameter. Further, the tip of the cylindrical heat insulating material 39 forming the peripheral wall of the flow hole 37 is tapered and enters the enlarged diameter portion of the connection ring 47. Other configurations are similar to those of the embodiment shown in FIGS. 1, 2 and 3. In this example, the connection ring
Since the diameter is expanded by 47, the ceramic heat transfer tube 22 can be formed into a cylindrical shape having an equal diameter over substantially the length direction, and there is an advantage that the ceramic heat transfer tube 22 can be easily manufactured.

FIG. 8 shows still another embodiment in which the connection structure of the heat transfer tubes is changed. Also in this embodiment, the end of the ceramic heat transfer tube 22 is pressed against the holding ring 29 via the connecting ring 47. The other structure is the same as that of the embodiment shown in FIG.

FIG. 9 shows still another embodiment in which the connection structure of the heat transfer tubes is changed. Also in this embodiment, the end of the ceramic heat transfer tube 22 is pressed against the holding ring 29 via the connecting ring 47. Other configurations are similar to those of the embodiment shown in FIG.

Further, in the case of having the connection structure shown in FIGS. 4 and 8, instead of the spring 36, a fluid pressure cylinder may be adopted as the pressurizing means as in the example of FIG.

[Advantages of the Invention] As described above, according to the present invention, the holding ring provided on one of the tube plates is directly or indirectly brought into pressure contact with one end surface of the ceramic heat transfer tube by the pressurizing means, and the attachment ring is attached. Since the other end surface of the ceramic heat transfer tube is brought into pressure contact with the other tube sheet directly or indirectly by force, the axial displacement of the retaining ring should absorb the axial displacement due to the difference in coefficient of thermal expansion and dimensional error. You can In addition, the contact surfaces of the ceramic heat transfer tube, the retaining ring, the receiving surface, and further the connection ring were smoothed so that the surface roughness was 6.3 S or less, so that the contact surfaces at both ends of the ceramic heat transfer tube were misaligned. As a result, the radial displacement of the heat transfer tube is easily absorbed, and the contact surfaces at both end surfaces of the ceramic heat transfer tube are in close contact with each other, so that fluid leakage can be reliably prevented. Therefore, 1000
It can be applied to heat exchange in a field where the temperature is higher than 0 ° C and leakage is not allowed.

[Brief description of drawings]

FIG. 1 is a sectional view showing an embodiment of a ceramic heat exchanger according to the present invention, FIG. 2 is a partial sectional view showing a connecting structure of a retaining ring portion of the heat exchanger, and FIG. 3 is AA in FIG.
4 and 5 are partial sectional views showing other embodiments in which the connection structure of the retaining ring portion of the heat exchanger is changed, and FIG. 6 is a ceramic heat exchange according to the present invention. Fig. 7 is a sectional view showing another embodiment of the heat exchanger, Fig. 7 is a partial sectional view showing the connecting structure of the retaining ring portion of the heat exchanger, and Figs. 8 and 9 are connecting of the retaining ring portion of the heat exchanger. FIG. 10 is a partial cross-sectional view showing another embodiment in which the structure is changed, and FIG. 10 is a partial cross-sectional view showing a conventional example of the connecting structure of the end portion of the ceramic heat transfer tube. In the figure, 21 is a heat exchanger, 22 is a heat transfer tube, 23 and 24 are tube plates, 25,
26 is a header, 27 is a flow path, 28 is a water cooling jacket, 29 is a retaining ring, 30 is a receiving surface, 36 is a spring, 37 is a flow hole,
38 is an expansion joint, 40 is a cylinder, 44 is a piston, and 45 is a cylinder.

Claims (9)

[Claims] 1. A ceramic heat exchanger in which both ends of a ceramic heat transfer tube are supported by a pair of metal tube plates that are arranged to face each other, and a holding ring is provided corresponding to a fluid passage hole of one of the tube plates. The holding ring is arranged in pressure contact with one end surface of the ceramic heat transfer tube by a pressurizing means provided between the holding ring and the tube sheet, and the other end of the ceramic heat transfer tube is biased by the urging force. The end surface is pressed against and supported by the receiving surface of the other tube sheet, and the contact surfaces between the both end surfaces of the ceramic heat transfer tube and the holding ring and the receiving surface have a surface roughness of 6.3 S or less. Ceramic heat exchanger characterized by being smoothed. 2. The holding ring according to claim 1, wherein a tubular body extending in the axial direction of the ceramic heat transfer tube is formed, and the tubular body is in sliding contact with the inner circumference of the through hole of one of the tube sheets. Ceramic heat exchanger. 3. The ceramic heat exchanger according to claim 1 or 2, wherein the pressurizing means is a spring or a fluid pressure cylinder. 4. The tube sheet according to any one of claims 1 to 3, wherein the tube plate has a water cooling structure, and the retaining ring and the pressurizing means are arranged in a portion surrounded by the water cooling structure. Is a ceramic heat exchanger. 5. A ceramic heat exchanger in which both ends of a ceramic heat transfer tube are supported by a pair of metal tube plates that are arranged opposite to each other, and a holding ring is provided corresponding to a fluid passage hole of one of the tube plates. The holding ring is arranged in pressure contact with one end surface of the ceramic heat transfer tube by a pressurizing means provided between the holding ring and the tube plate via a connecting ring, and the ceramic is applied by its urging force. The other end surface of the heat transfer tube is also pressed against and supported by the receiving surface of the other tube sheet via the connecting ring, and the ceramic heat transfer tube, the connecting ring, the holding ring and the receiving surface are brought into contact with each other. A ceramic heat exchanger characterized in that its surface is smoothed to a surface roughness of 6.3 S or less. 6. The ceramic heat exchanger according to claim 5, wherein the connection ring has a tapered inner diameter. 7. The holding ring according to claim 5 or 6, wherein a tubular body extending in the axial direction of the ceramic heat transfer tube is formed, and the tubular body is provided in a through hole of one of the tube sheets. Ceramic heat exchanger that is in sliding contact with the circumference. 8. A ceramic heat exchanger according to any one of claims 5 to 7, wherein said pressurizing means is a spring or a fluid pressure cylinder. 9. The tube sheet according to any one of claims 5 to 8, wherein the tube sheet has a water cooling structure, and the holding ring and the pressurizing means are arranged in a portion surrounded by the water cooling structure. Is a ceramic heat exchanger.