JPH0318113B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a shell-and-tube heat exchanger mainly used for heat exchange with a heat transfer fluid at a temperature exceeding 1000°C.

(Prior art) Conventional shell-and-tube heat exchangers typically use metal tubes such as stainless steel tubes as heat transfer tubes, but the allowable heat resistance temperature of stainless steel tubes is approximately 800°C, and it is Even if internal cooling is considered, it cannot be used for heat exchange with high temperature exhaust gas of 1000℃ or higher, and stainless steel pipes are easily corroded by exhaust gas, so the range of use is greatly limited depending on the composition of the exhaust gas. There were some drawbacks. Therefore, attempts have been made to use ceramic tubes, which have excellent heat resistance and corrosion resistance, as heat transfer tubes, but unlike metal tubes, ceramic tubes require processing such as fins on the inner surface of the conduit to improve heat transfer characteristics. Because of this, a thick temperature boundary layer is formed as the heat transfer fluid flows inside the tube, making it difficult to reduce the heat transfer resistance inside the tube, especially when low-temperature heat transfer fluid flows through the tube. This drawback is noticeable in
On the outer surface of the pipe, which is in contact with the heat transfer fluid at a temperature exceeding 1000°C, radiation heat transfer becomes dominant and the heat transfer resistance decreases, but on the inner surface of the pipe there is a large heat transfer resistance due to a thick temperature boundary layer. There was a problem in that the heat transfer efficiency could not be improved because of the presence of the metal.

(Object of the invention) The present invention solves these conventional problems.
Can be used in high temperature ranges exceeding 1000℃,
Moreover, it was completed for the purpose of a heat exchanger using ceramic tubes as heat transfer tubes, which can obtain high heat transfer efficiency.

(Structure of the Invention) The present invention forms a heat transfer fluid flow path in the interior of opposing frames provided with a supply port and an outlet for a fluid to be heated, and a large number of ceramics connected to the supply port and the outlet. In a heat exchanger in which tubes are arranged side by side, a plurality of ceramic sub-fluids each having a central hole and radial partition walls that subdivide the pipeline of the ceramic tubes are inserted in the axial direction into each of the ceramic tubes. This is a characteristic feature.

Next, the present invention will be described in detail with reference to the illustrated embodiments.

In the figure, reference numeral 1 denotes a metal frame having openings on both the upper and lower sides, and the inside of which is formed as a flow path for heat transfer fluid such as high-temperature exhaust gas. A fluid inlet chamber 3' having a supply port 3 for the fluid to be heated and a fluid outlet chamber 4' having an outlet 4 are provided on the outside of the heated fluid. 5 is a ceramic tube made of a ceramic material with excellent heat resistance and corrosion resistance, such as silicon carbide, and fins 6 are preferably formed on the surface of the ceramic tube to increase the heat transfer area. Reference numeral 5 denotes a number of through holes 10, which are sandwiched between the hexagonal columnar wall structures 7 and 7', and are provided on both sides of the wall structures 7 and 7'.
metal support tubes 8 and 9, one end of which is inserted into and supported by 10' and communicates with the supply port 3 and the outlet port 4;
A large number of ceramic tubes 5 are arranged in parallel between the wall surfaces 2 and 2'. In addition, the wall structure 7,
7' is made of a ceramic material such as silicon carbide similarly to the ceramic tube 5, and through holes 11, 11', which are equal to the inner diameter of the ceramic tube 5, are provided in the center in the axial direction. ，
The joint surfaces 12, 12' between the support tubes 7' and the ceramic tubes 5, and the joint surfaces 13, 13' between the wall structures 7, 7' and the support tubes 8, 9 are all formed into spherical surfaces.
Further, the support pipe 8 on the inflow side is surrounded by a compression spring 14, and the compression spring 14 is welded around a flange 15 protruding from the front part of the support pipe 8 and a through hole 10 in the wall surface 2. The support tube 8 is provided between the ceramic tube 16 and the ceramic tube 5, and presses the wall structure 7 toward the ceramic tube 5 via the support tube 8. Furthermore, as shown in FIG. 1, the outer support tube 9 of the other wall structure 7' has a retaining flange 17 at its rear part, and supports the wall structure 7' immovably. Therefore, the ceramic tube 5 is elastically installed between the walls 2 and 2' by the elastic force of the compression spring 14 with both ends thereof being held between the wall structures 7 and 7', and expands in the axial direction. , contraction is absorbed by the compression spring 14, and the ceramic tube 5 is connected to the fluid inflow chamber 3' by inserting the support tube 8 and the support tube 9 into the through holes 10 and 10' in the walls 2 and 2', respectively. By communicating with the fluid outflow chamber 4', a flow path for the heated fluid flowing through the inside of the ceramic tube 5 is formed. Note that the wall structure 7,
Reference numeral 7' indicates that when all the ceramic tubes 5 are installed between the walls 2 and 2', their outer surfaces are in close contact with each other to form airtight walls on both sides of the interior of the frame 1. By making the inside surrounded by the body a heat transfer fluid flow path through which high-temperature exhaust gas, etc. flows, leakage of exhaust gas is prevented, and the compression spring 1
It acts as a heat insulating wall for the support tube 8 with 4 and prevents the elasticity of the compression spring 14 from decreasing.
Furthermore, a plurality of ceramic fluid dividers 18 as shown in FIG. become The fluid division 18 is a narrow cylindrical portion 2 with a center hole 24.
A plurality of wing-shaped partition walls 26 are stretched radially on the outer surface of the ceramic tube 5, and the end of each fluid branch 18 is formed into a convex end surface 27, and the outer diameter of the partition wall 26 is the same as that of the ceramic tube 5. It is approximately equal to the inner diameter. Note that such a divided fluid 18 may be inserted not only into the inside of each ceramic tube 5 but also into the wall structure 7, and its length should be about a fraction of the length of the ceramic tube 5. is preferable from the viewpoint of molding technology.

This structure allows high-temperature exhaust gas discharged from various industrial furnaces to flow through the heat transfer fluid channel inside the frame 1, and also to flow through the through holes 10, 10' in the opposing wall surfaces 2, 2'. If room-temperature air is sent from the supply port 3 through the support tubes 8 to a large number of ceramic tubes 5 that have support tubes 8 and 9 connected to each other at both ends, high-temperature exhaust gas will flow through the walls of these ceramic tubes 5. The fact that heat exchange is carried out between the heat exchanger and air is the same as in conventional heat exchangers of this type, but in the present invention, ceramic tubes 5 with excellent heat resistance and corrosion resistance are used as heat transfer tubes. It is possible to exchange heat between the heat exchanger and exhaust gas at a temperature of over 1000°C, and has far superior temperature efficiency compared to conventional heat exchangers that can only be used for exhaust gas at temperatures below 1000°C. In addition, it is possible to recover heat from corrosive gases, which was not possible with heat exchangers using metal heat transfer tubes. In addition, a center hole 2 is provided in the ceramic tube 5 to subdivide the channel of the ceramic tube 5.
4 and radial partition walls 26 are inserted in the axial direction, the heat transfer fluid such as air is finely divided by the central hole 24 and the radial partition walls 26. As a result, the heat transfer surface to the heated fluid becomes larger, and the thickness of the temperature boundary layer that controls the convective heat transfer resistance on the inner surface of the ceramic tube 5 is significantly thinner than in the case without the dividing fluid 18. As a result, the heat transfer resistance on the inner surface of the pipe is reduced, and the overall heat transfer efficiency can be improved. Moreover, since the heat transfer fluid leaving the divided fluid 18 is mixed when entering the next divided fluid 18, the central hole 2
The temperature of the heat transfer fluid passing through the center hole 2 and the heat transfer fluid passing through the radial partition wall 26 becomes uniform, and the temperature of the heat transfer fluid passing through the center hole 2 becomes uniform.
Coupled with the fact that the wall thickness of the ceramics forming the divided fluid 18 is made uniform by forming the divided fluid 18, thermal damage to the divided fluid 18 can be reliably prevented. Furthermore, when the end of the fluid divider 18 is formed into a convex end surface 27, it is possible to forcefully stir the heat transfer fluid at the joint part with the adjacent fluid divider 18, thereby improving the heat transfer efficiency. Further improvements can be made. In addition, if the partition walls 26 of the fluid division 18 are formed at equal intervals as shown in the figure, the cross-sectional area of the pipe can be made equal, and pressure loss due to uneven flow can be prevented, and pressure loss can be prevented throughout the pipe. A uniform heat transfer surface is formed, which is effective in improving heat transfer efficiency.
Further, the divided fluid 18 also has the effect of reinforcing the ceramic tube 5 and preventing its damage.

(Effects of the Invention) As is clear from the above description, the present invention uses ceramic tubes as heat transfer tubes, so heat can be recovered by a conventional shell-and-tube heat exchanger using metal heat transfer tubes. It is possible to efficiently recover heat from high-temperature exhaust gas of 1000℃ or more and corrosive gas, which previously could not be carried out. Moreover, each ceramic tube has a central hole that subdivides the conduit of the ceramic tube. By inserting multiple fluid dividers with radial partition walls in the axial direction, the thickness of the temperature boundary layer on the inner surface of the ceramic tube, which was previously difficult to process to improve heat transfer characteristics, can be significantly increased. It is possible to obtain high heat transfer efficiency by reducing the heat transfer resistance on the inner surface of the ceramic tube, which previously controlled the overall heat transfer efficiency, since it is possible to reduce the amount of heat transfer and allow fluid mixing between the divided fluids. This is an extremely useful product that contributes to the development of the industry by solving the problems of this type of heat exchanger.

[Brief explanation of the drawing]

FIG. 1 is a partially cutaway front view showing an embodiment of the present invention, FIG. 2 is a partially cutaway front view of the main part, and FIG. 3 is a perspective view of a fluid divider. 1: Frame body, 2, 2': Wall surface, 3: Supply port, 4:
Outlet, 5: Ceramics tube, 18: Dividing fluid, 2
4: center hole, 26: partition wall, 27: convex end surface.

Claims (1)

[Claims] 1. The inside of the opposing frame body 1 provided with a supply port 3 and an outlet port 4 for heated fluid is formed into a heat transfer fluid flow path,
In a heat exchanger in which a large number of ceramic tubes 5 are arranged in parallel and communicate with the supply port 3 and the outlet port 4, each ceramic tube 5 has a center hole 24 and radial partition walls that subdivide the conduit of the ceramic tubes. 26. A heat exchanger characterized in that a plurality of ceramic fluid divisions 18 having 26 are inserted in the axial direction. 2. The heat exchanger according to claim 1, wherein the divided fluid 18 has an end formed with a convex end surface 27.