JPH0221518B2 - - Google Patents

Description

[Detailed description of the invention] This invention relates to a double tube heat exchanger.

The double tube heat exchanger has an outer tube made of ceramics,
This is a heat exchanger that uses a double tube with an inner tube made of steel, and is known for its excellent heat resistance and corrosion resistance. A specific structure of this double-tube heat exchanger has already been proposed by the applicant of the present application as Utility Model Publication No. 43109/1983.

Figure 1 shows its structure. In the figure, X is the flue of the heating furnace, 50 is a ceramic outer tube, 51 is a steel inner tube, 52 and 53 are headers on the primary side and secondary side, respectively.
54 is a fluid reversing brick, and the outer tube 50 is supported by the inner tube 51 from below via a spring 55. According to this configuration, it is possible to closely follow the thermal expansion and contraction of the heat exchanger tube, and it has an excellent effect that there is no damage to the outer tube.

However, in this configuration, the spring 55
Since it was installed at the bottom, there was a drawback that it could not be installed if there was no space at the bottom of the flue. In particular, in the case of general existing furnaces, although there is a space at the top, there is often no space at the bottom, which has the disadvantage that the number of furnaces that can adopt this configuration is limited.

The present invention has been made to improve these drawbacks, and consists of a ceramic outer tube installed in the flue of a heating furnace, etc., and a steel inner tube installed inside the outer tube and communicating with it. A double tube heat exchanger having heat transfer tubes, the basic feature of which is that the inner tube is suspended from the upper part of the flue via a spring, and the lower end of the outer tube is supported at the lower end of the inner tube. It is.

The present invention will be explained below based on examples.

In FIG. 2, 1 is an outer tube made of fine ceramics, and 2 is an inner tube made of steel that is fitted inside the outer tube 1. The inner pipe 2 passes through the secondary air header 6 and
It reaches the next air header 5, where it is opened by a hole 20. A suspension rod 21 is provided at the tip of the inner tube 2 to protrude upward. This inner tube 2 and 2
A gland packing 22 is installed between the next air header 6.
is interposed thereon, and a support tube 30 which also serves as a packing holder is loosely fitted onto the rod 21 and the inner tube 2 body. On this support tube 30, a spring seat 31,
A helical spring 3 and a spring seat 32 are loosely fitted into the rod 21, respectively. Further, a nut 23 is attached to the tip of the rod 21 to restrict upward movement of the spring 3. With this configuration, the inner tube 2 is suspended above the secondary air header 6 via the spring 3. In addition, the support tube 30
A hole 300 is formed at a position corresponding to the hole 20.

The outer tube 1 has an opening 6 in the header 6 at its upper end.
0 and communicates with the inside of the header 6. In addition, a fluid reversing brick 4 is attached to the lower end.
This brick 4 is fitted into the lining Y of the flue X with a predetermined gap.

A hole 24 is provided at the lower end of the inner tube 2, through which it communicates with the reversing brick 4 and the outer tube 1.
The lower end of the inner tube 2 is further provided with an inverted brick support fitting 25.
is provided, which penetrates the bottom surface of the reversible brick 4 and has a structure in which the outer tube 1 is supported from below by a locking portion 250 at its lower end. This locking part 2
A seal 26 is interposed between 50 and the reversing brick 4.

In the above configuration, preheated air enters the inner pipe 2 from the primary air header 5, turns inside the reversing brick 4, enters the outer pipe 1, rises while being heated here, and flows into the secondary air header 6. It is collected and used as preheated air.

Thermal expansion of the ceramic outer tube 1 is controlled by the support fitting 25.
→It is absorbed by the spring 3 through the inner tube 2. Therefore, the ceramic material can be freely selected without worrying about the coefficient of thermal expansion of the ceramic. Furthermore, since the outer tube 1 is supported from the lower end side by the inner tube 2, no tensile stress is generated and compressive stress is always generated, so that there is no adverse effect on the ceramic material.

Further, since the spring 3 is located above the flue X, it can be attached anywhere as long as there is space above the flue, and the spring adjustment can be easily performed in a stable posture.

In addition, in the embodiment shown in FIG. 2, there is a possibility that the inner tube 2 may bend due to a difference in thermal expansion between the side facing the exhaust gas flow (arrow) and the opposite side of the inner tube 2. A gap is created between the portion 250 and the bottom surface of the reversing brick 4, which may cause air leakage. Further, a force that tends to tilt the reversing brick 4 is also applied, which is undesirable. In order to prevent this, it is desirable to adopt the configurations shown in FIGS. 3 to 5.

That is, in the embodiment shown in FIGS. 3 and 4, the support fitting 25' and the inner tube 2 are connected by the pin 27, so that the deflection of the inner tube 2 is not transmitted to the support fitting 25'. There is. This pin connection is configured so that the connection portion can be bent in the flow direction of the exhaust gas.

Further, instead of the pin connection, a universal joint 28 may be provided at the lower end of the inner tube 2 to form a universal joint connection. In this case, since it can be bent not only in the flow direction of the exhaust gas but also in all directions of 360 degrees, the adhesion between the support fitting 25'' and the lower surface of the anti-brick 4 is improved.

As explained above, according to the present invention, no unreasonable force is applied to the ceramic outer tube of the double tube, and its thermal expansion can be effectively absorbed.
In addition, since the spring is located at the upper part of the flue, it can be installed even if there is no space at the lower part of the flue, and the spring can be adjusted in a stable posture.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram of the prior art, FIG. 2 is a front sectional view showing one embodiment of the present invention, FIG. 3 is a partial sectional view showing another embodiment of the lower structure, and FIG. FIG. 5 is a partial sectional view showing still another embodiment. In the figure, 1...Outer pipe, 2...Inner pipe, 3...Spring, 4...Fluid reversing brick, 5...Primary side air header, 6...Secondary side air header.

Claims (1)

[Claims] 1. In a double-tube heat exchanger having a heat transfer tube consisting of a ceramic outer tube installed in the flue of a heating furnace, etc. and a steel inner tube installed inside the outer tube and communicating with it, the inner tube A double tube heat exchanger, characterized in that the tube is suspended from the upper part of the flue via a spring, and the lower end of the outer tube is supported at the lower end of the inner tube.