JPH0148480B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a cross-flow type heat exchanger used for recovering heat from exhaust gas discharged from various industrial furnaces.

(Prior art) Conventional cross-flow type heat exchangers mainly use stainless steel pipes as heat transfer tubes for circulating the heated fluid, so they cannot be used for heat exchange with high-temperature exhaust gas of 1000°C or higher. There was a drawback that I couldn't do it. Therefore, as shown in Special Publication No. 57-51037,
Attempts have been made to use ceramic tubes with excellent heat resistance and corrosion resistance as heat transfer tubes, but the heat exchanger shown in the above publication has a structure in which both ends of a uniformly thin ceramic tube are supported by heat-resistant members. For,
If large thermal expansion occurs in the ceramic tube when it comes into contact with high-temperature heating fluid, both ends of the ceramic tube may be damaged, and the difference in thermal expansion between the ceramic tube and the heat-resistant member may cause gas leakage from the joint surface between the two. I was afraid. Furthermore, if the spring that presses the heat-resistant member against the ceramic tube 2 is made strong in order to prevent gas leakage from the joint surface, there is a drawback that both ends of the ceramic tube that come into contact with the heat-resistant member are likely to be chipped.

(Object of the invention) The present invention solves these conventional problems.
The aim was to create a heat exchanger that could not only be used for high-temperature exhaust gases of 1000℃ or higher, but also eliminate the risk of ceramic tube damage or gas leaks, and achieve extremely high heat exchange efficiency. It is what was done.

(Structure of the Invention) The present invention provides a cross-flow type heat exchanger in which a large number of ceramic tubes each having a through hole through which a heated fluid flows is installed in a frame body through which a high-temperature heating fluid flows. The wall structure is thin and thick with both ends bulging in the outer circumferential direction, and the end faces of both ends are formed into a convex shape, and these end faces are formed into a wall structure having a concave joint surface by an axial spring force. They are brought into close contact with each other, and will be described in detail below using an example of a two-pass heat exchanger shown in the drawings.

In the figure, 1 is a metal frame having openings on both the upper and lower sides, and the inside thereof is formed into a flow path through which high-temperature heated fluid such as exhaust gas flows in the direction of the arrow, and 2 is the frame 1.
This is a ceramic tube in which a large number of ceramic tubes are installed in a direction perpendicular to the flow direction of high-temperature heating fluid. The ceramic tube 2 is made of a ceramic material with excellent heat resistance and corrosion resistance, such as silicon carbide, and the central portion 3 has a wall thickness of 1.
It is formed with a thin wall of about 10 mm to 10 mm, and both ends 4
As shown in the figure, it is thicker than the central portion 3, and its end surfaces 5 are formed in a convex shape. In order to make both ends 4 of the ceramic tube 2 thick, the thickness of the ends 4 can be increased in the outer circumferential direction as shown in FIG.
Alternatively, as shown in FIGS. 4 and 5, an end piece 7 made of silicon carbide may be joined to one or both ends via a sealing material 6, or any structure may be adopted. However, the ceramic tube 2 has a through hole 8 inside thereof through which air or other fluid to be heated passes, and if the wall thickness of both ends 4 is increased in the inner diameter direction, the inside diameter of the through hole 8 is reduced at both ends. Therefore, it is preferable that the inner diameter of the central portion of the through hole 8 is substantially the same as the inner diameter of both ends, as shown in the figure. Ceramic tube 2
A large number of fins 9 are formed in the thin part of the central part 3 to expand the heat transfer area, and it is also possible to form irregularities inside the fins or insert a dividing fluid as necessary. . As shown in FIGS. 1 and 2, both thick-walled ends 4 of these ceramic tubes 2 have a through hole 10 in the center that communicates with the through hole 8, and are continuous when stacked. Each is supported by a hexagonal columnar wall structure 11 that constitutes a wall. Similarly to the ceramic tube 2, the wall structure 11 is also made of a ceramic material such as silicon carbide, and the joint surfaces 12 with the convex end portions 5 of both ends 4 of the ceramic tube 2 are recessed into a concave shape to temporarily form a ceramic tube. Even if curvature occurs in the ceramic tube 2 due to thermal strain, airtightness is maintained between the ceramic tube 2 and both ends 4. One of these wall structures 11 is supported by the left wall surface 13 of the frame 1 via an adapter 14, and the other wall structure 11 slides on the right wall surface 15 of the frame 1 with a telescopic mechanism 16 in between. freely supported. The expansion mechanism 16 is composed of a long adapter 17 and a coil spring 18 provided on its outer periphery, and each ceramic tube 2 is individually moved inside the frame 1 by the spring force acting in the axial direction. Even if a difference in thermal expansion occurs between the ceramic tubes 2, the stacked wall structures 11 will simply slide, and excessive stress will not be applied to the ceramic tubes 2, etc. Prevented. Note that 19 is a fluid supply chamber for introducing the fluid to be heated into a predetermined ceramic tube 2 forming the first pass, and 20 is a chamber for mixing the fluid to be heated that has passed through the ceramic tube 2 of the first pass. A heated fluid mixing chamber 21 circulates the heated fluid into the ceramic tube 2 of the second pass, and a heated fluid chamber 21 collects the heated fluid exiting the second pass.

This structure supplies high-temperature heating fluid such as exhaust gas discharged from various industrial furnaces to the inside of the frame 1, and also supplies the fluid to the inside of a large number of ceramic pipes 2 installed inside the frame 1. When a heated fluid such as air is supplied from the supply chamber 19, the heated fluid enters the heated fluid mixing chamber 20 while receiving heat from the high-temperature heated fluid through the wall surface of the ceramic tube 2, and further passes through the second pass. The process of taking out the fluid through the ceramic tube 2 and into the heated fluid chamber 21 is the same as in the conventional system. However, in the present invention, the ceramic tube 2
Since the central part 3 is thin and both end parts 4 are thick, heat exchange between the high-temperature heated fluid and the fluid to be heated is carried out extremely efficiently through the thin central part 3. Even if large thermal expansion occurs, both ends 4, which are thickened and have increased strength, will not be damaged. Moreover, since the end surfaces 5 of the thick end portions 4 are formed in a convex shape and pressed tightly against the concave joint surface 12 of the wall structure 11 in the axial direction by a spring force, the ceramic tube 2 There is no risk of gas leakage even if curved due to thermal strain occurs in the ceramic tube 2, and the coil spring 18 of the expansion mechanism 16 is strong enough to completely prevent gas leakage.
There is no risk of chipping or the like.

(Effects of the Invention) As is clear from the above description, the present invention has an advantage in that it is not possible to recover heat with the conventional cross-flow type heat exchanger using metal heat transfer tubes.
It can efficiently recover heat from high-temperature exhaust gas of 1000℃ or more and corrosive gas.
Further, even if large thermal expansion occurs in the ceramic tube due to contact with high-temperature heating fluid, there is no risk of damage to both ends of the ceramic tube or gas leakage. Furthermore, heat exchange between the high-temperature heating fluid and the heated sulfur body is carried out efficiently through the thin central part, making it possible to obtain extremely high heat exchange efficiency, which is superior to conventional heat exchangers of this type. It is a major contribution to the development of the industry as it solves problems.

[Brief explanation of drawings]

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.
The figure is a partially cutaway front view of a ceramic tube, and FIGS. 4 and 5 are partially cutaway front views showing ceramic tubes of other embodiments. 1: Frame body, 2: Ceramic tube, 3: Center part,
4: both ends, 5: end face, 9: fin.

Claims (1)

[Scope of Claims] 1. In a cross-flow type heat exchanger in which a large number of ceramic tubes 2 having through holes 8 through which a fluid to be heated flows is installed in a frame body 1 through which a high-temperature heated fluid flows, the ceramic tubes 2 The central portion 3 is thin and both end portions 4 are thick and bulge in the outer circumferential direction, and both end portions 4 are thick.
A heat exchanger characterized in that the end faces 5 of the heat exchanger are formed in a convex shape, and each of these end faces 5 is brought into close contact with a wall structure 11 having a concave joint surface 12 by an axial spring force. 2. The heat exchanger according to claim 1, wherein the ceramic tube 2 has fins 9 formed on the surface of the thin portion of the central portion 3. 3 Ceramic tube 2 with a wall thickness of 1 mm-10 at the center part 3
The heat exchanger according to claim 1 or 2, wherein the heat exchanger is mm. 4. The heat exchanger according to claim 1, 2, or 3, in which the ceramic tube 2 is made of silicon carbide.