JPS5931669B2 - Helical coil type intermediate heat exchanger - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to improvements in helical coil type intermediate heat exchangers used in nuclear reactor cooling systems.

The purpose of the present invention is to eliminate forced displacement caused by thermal expansion in supporting heat transfer tubes and to reduce thermal stress as much as possible, and to enable firm support in low temperature regions in supporting inner cylinder tubes. There is a particular thing.

A helical coil type intermediate heat exchanger has been developed as an intermediate heat exchanger for extremely high temperatures used in nuclear reactor cooling systems. The feature of the helical coil type intermediate heat exchanger is that approximately 420 heat exchanger tubes are wound into a helical coil shape and installed in the heat exchange chamber without interfering with each other. It is necessary to elastically support a group of heat exchanger tubes wound in a helical coil shape so that they do not interfere with each other, do not cause vibrations, etc., and allow thermal expansion and relieve thermal stress. It's quite difficult. At present, it is supported by support plates arranged radially.

However, the solution to the relative elongation difference caused by thermal expansion between the heat exchanger tube and the support plate remains unsolved. Next, in the inner cylindrical tube, the cylindrical space originally formed at the center of the helical coiled heat transfer tube group forms a flow path with low flow resistance, and prevents the high temperature primary fluid from flowing through this as a short-circuit flow. was used to.

However, it was noticed that the use of the inner tube was not limited to simply providing flow resistance against short-circuit flow, but that it could also be used as an independent conduit, and this use was considered. Support became an issue. In order to solve the above-mentioned problems regarding the helical coil type intermediate heat exchanger, the present invention has decided to attach a support plate directly to the inner cylindrical tube to support the heat transfer tube.

This allows approximate thermal expansion to occur in the heat exchanger tube and support plate, thereby solving the problem of thermal stress. Further, according to the present invention, the inner tube is supported by the low-temperature side tube plate in the low-temperature region, and the high-temperature secondary fluid heated by heat exchange is guided to the external system through the inner tube. This is also a feature.

The present invention will be explained below with reference to illustrated embodiments.

The body of the helical coil type intermediate heat exchanger is a straight tube! It is used with its tube axis in the vertical direction. The structure of the shell container can be roughly divided into three parts. These include a central straight tube part (body part) 1, an upper lid part 1' that closes the upper part, and a lower lid part f that closes the lower part. The straight pipe part 1, the upper lid part 1', and the lower lid part f have respective flange parts 1a and 1a.
5 and 1b and 1bi are watertightly connected with connecting bolts or the like. The straight pipe section 1 has an inflow section 2 for a high temperature primary fluid at its lower part, and an outlet section 3 for a low temperature primary fluid at its upper part.

The high temperature primary fluid that has reached the inlet portion 2 flows into the heat exchange chamber 5 via the distributor 4 as a uniform flow in the circumferential direction. A concentrically arranged intermediate pipe 6 is attached to the inside of the straight pipe section 1, and a flow path r for a low-temperature primary fluid is formed.

The upper and lower ends of the intermediate pipe 6 are respectively joined to the straight pipe section 1 in a watertight manner. Furthermore, an inlet section 8 and an outlet section 9 for the low-temperature primary fluid are provided at the upper and lower portions of the flow path r.

The high temperature primary fluid inlet section 2 and the low temperature primary fluid outlet section 9
It is said to have a double piping structure. A cylindrical heat exchange chamber 5 is formed by a heat insulating material 10 lined inside the straight pipe section 1 and an inner wall tube 11 located on the inner surface of the heat insulating material. The upper lid part V has a cone-shaped low-temperature side tube sheet 12, and an inner cylindrical tube 13 passing through the low-temperature side tube sheet 12 extends downward through the center of the body container.

The inner tube 13 and the low temperature side tube sheet 12 are joined watertightly,
The inner cylindrical tube 13 is suspended and supported by this low temperature side tube plate 12. The lower end of the inner cylindrical pipe 13 includes a straight pipe part 1 and a lower lid part 1.
Approximate elastic support is provided to the free end by the heat insulating materials 10 and 14 filled in the upper cover part 1'. 16 forms a flow chamber 15 for low-temperature secondary fluid.

The low-temperature secondary fluid inlet portion 1r communicating with the inflow chamber 15 has a double piping structure concentric with the inner shaft pipe 13.

The inner cylindrical pipe 13 carries the high-temperature secondary fluid heated by heat exchange.
Used as a conduit to the outside system.

For this reason, the inner cylindrical pipe 13 has a so-called high-temperature piping structure in which the inner surface thereof is lined with a heat insulating material 135. The lower end portion of the inner cylindrical tube 13 is formed as a large diameter portion 18 having an oval vertical cross section and is closed.

This large diameter portion 18 has a heat insulating material 10 filled around it,
14 and spacer 23, it is held elastically to the extent that it does not sway. Gaps 19 and 20 are formed to allow thermal expansion of the inner sleeve tube 13 in the axial direction.
The inner cylindrical tube 13 has a required number of support plates 21 that protrude radially from the outer diameter surface thereof and continue in a straight line in the tube axis direction with the same thickness and width (the required number of support plates 21 are shown in FIG. In the example 4
) are integrally installed.

A heat transfer tube 22 wound in a helical coil shape is passed through each of the support plates 21, and is properly held at a predetermined pitch by the support plates 21 so as not to cause vibration or interference. . The upper end of each heat transfer tube 22 is watertightly joined to the low-temperature side tube plate 12 and communicated with the inflow chamber 15 for the low-temperature primary fluid.

Further, the lower end of each heat transfer tube 22 is connected to the large diameter portion 18 at the lower end of the inner cylinder tube.
The tube wall of the large diameter portion 18 is connected to the tube wall of the large diameter portion 18 and communicates with the inside of the inner tube.
Therefore, in the above intermediate heat exchanger, approximately 9
A high temperature primary fluid of about 80°C is supplied, and when it rises through the heat exchange chamber 5 and reaches the outlet section 3, the temperature is about 370°C.
The temperature has dropped to a certain extent. The primary fluid that exited the outlet section 3 is
After passing through a circulator (not shown) and adjusting the temperature to about 400°C, the water is guided to the artificial part 8 of the flow path r on the outer diameter of the shell container, and while passing through the flow path 7, it exerts a forced cooling effect on the shell container. , exit through exit section 9.

At this time as well, the liquid flows through the outer diameter portion of the double pipe, producing a forced cooling effect of the pipe. - On the other hand, the low temperature primary fluid is about 30
At a temperature of about 0° C., it is supplied to the inflow chamber 15 from the inlet portion 1r, which has a double structure concentric with the inner cup pipe 13.

Then, it is divided into each heat transfer tube 22 and descends through the heat exchange chamber 5 to reach the inside of the large diameter portion 18 at the lower end of the inner tube. At this time, the vorticity is approximately 9300C. The high-temperature secondary fluid is guided to an external system through the inner cylinder pipe 13. According to the intermediate heat exchanger of the present invention having the above structure and operating as described above, since the heat transfer tube group is supported by the support plate 21 attached to the inner tube 13, the following advantages can be obtained. That is, the inner cylindrical tube 13 and the support plate 21 can freely and equally thermally expand without being restricted by any other system. In addition, the inner cylinder tube 13, the support plate 21. Since the heat exchanger tubes 22 are under the same temperature distribution, they each undergo approximate thermal expansion. Therefore, each heat exchanger tube 22 is supported without being forcibly displaced, and thermal stress can be significantly alleviated, which is very advantageous in terms of strength. Moreover, the inner cylindrical pipe 13 is
Since it is supported by the tube sheet 12 at a low temperature of about 300'C to 400C, it is also advantageous in terms of strength. Thus,
According to the present invention, the high-temperature strength design that is inevitable for a high-temperature heat exchanger can be advantageously advanced, and a highly safe intermediate heat exchanger can be provided.

[Brief explanation of the drawing]

FIG. 1 is a vertical cross-sectional view of a helical coil type intermediate heat exchanger improved according to the present invention, and FIG. 2 is a cross-sectional view taken from FIG. 1... Trunk container (straight pipe part), 2... Primary fluid inlet, 3
...Primary fluid outlet, 5...Heat exchange chamber, r...L-order fluid flow path, 10...Insulating material, 13...Inner cylindrical pipe, 1T
...Secondary fluid inlet, 22...Heat transfer tube.

Claims (1)

[Claims] 1 The inside of the straight tube-shaped shell container is lined with a heat insulating material, and a large number of coiled heat transfer tubes are installed in a heat exchange chamber formed inside the heat exchange chamber, and a high temperature primary fluid is introduced into the heat exchange chamber. In a high-temperature heat exchanger in which a low-temperature secondary fluid is passed through the heat transfer tubes, the upper part of the inner cylinder tube located at the center of the heat transfer tube group is supported by the low-temperature side tube plate, and the lower end thereof is The inner cylindrical tube is elastically supported with a structure that allows thermal expansion, and a plurality of support plates are installed on the inner tube that protrude in the radial direction and are continuous in the tube axis direction, and the heat transfer tube is wound around the support plates in a coil shape. The upper end of each heat transfer tube passes through the low-temperature side tube plate and communicates with the low-temperature secondary fluid inflow chamber, the lower end of each tube is connected to the lower chamber of the inner tube, and the upper end of each tube is connected to the lower chamber of the inner tube. A helical coil type intermediate heat exchanger, characterized in that the is configured as an outlet for high-temperature secondary fluid.