JPS60211205A - Protective device for heat transfer tube of steam generator - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a heat exchange type steam generator, and particularly to a protection device for heat exchanger tubes thereof.

Generally, in this type of steam generator, as shown in FIG. 7, each heat transfer tube l has its end fixed to the tube plate by seal welding 3, and the outer surface of the intermediate part is fixed to the tube support plate through the hole. The high temperature primary fluid is supported laterally by the arrow! As shown, the fluid flows inside the heat exchanger tube, exchanges heat with the secondary fluid (not shown) outside the heat exchanger tube, and evaporates it.

However, evaporation occurs over the entire outer surface of the heat transfer tube, that is, it also occurs across the narrow gap surrounded by the tube sheet a and the tube support plate d, so impurities in the secondary fluid condense in this gap and impurities transfer. Heat has been known to cause corrosion of tubes, tube plates and tube support plates.

Therefore, an object of the present invention is to eliminate the evaporation phenomenon of the secondary fluid in the gaps between the holes in the tube sheet and the tube support plate and the heat exchanger tubes, which may cause damage to the heat exchanger tubes due to corrosion. It can be easily installed inside heat transfer tubes with signs of
An object of the present invention is to provide a heat exchanger tube protection device that prevents the occurrence and progression of corrosion.

To achieve this objective, the heat exchanger tube protection device manufactured according to the present invention includes a plurality of cylindrical heat insulating members provided inside the heat exchanger tubes corresponding to the tube sheets and tube support plates, a heat insulating member corresponding to the tube sheets, A support member that removably fixes the member to the ice chamber side of the tube sheet, a first support means that connects the adjacent heat insulation members to each other in a flexible manner, and a heat insulation member corresponding to the tube sheet and the support member. Each heat insulating member is comprised of a heat insulating sleeve at the center and a wheel-shaped strength fitting at the end. The insulating sleeve prevents heat transfer from the primary fluid to the lined section of the heat exchanger tube, thereby preventing heat transfer into the narrow gap between the inner surface of the hole in the tube sheet and tube support plate and the outer surface of the heat exchanger tube. The amount of heat transferred is reduced, and evaporation in that area is suppressed. In addition, since the heat insulating sleeves are connected to each other via the first support rod, they can be easily inserted into the heat transfer tubes one after another. Since the protective device can be attached and detached freely, there are advantages such as easy installation of the protective device inside the heat exchanger tube.Next, a preferred embodiment of the present invention will be explained with reference to FIGS. 3 to 6. In the drawings, the same reference numerals used in FIGS. 1 to 1 indicate the same or corresponding parts, and further explanation thereof will be omitted.

Although the overall structure of the steam generator itself is not shown as it is known to those skilled in the art, the steam generator includes a number of heat exchanger tubes (only one is shown in the figure) in the body; The end of each heat transfer tube is inserted into the hole a of the tube plate and fixed therein by seal welding 3. In the drawing, the lower side of the tube plate,
That is, the outer side is the ice chamber, and the upper side is the steam generation section. The heat exchanger tube protection device of the present invention is installed on those that are likely to be damaged by corrosion or that have signs of damage among these many heat exchanger tubes.

In FIG. 3, the heat exchanger tube protection device according to the present invention includes a plurality of cylindrical heat insulating sleeves made of an appropriate heat insulating material capable of withstanding the high temperature and high pressure of the primary fluid flowing inside the heat exchanger tube l, and io. At both ends of the heat insulating sleeves 9 and io, metal reinforcing members /I, / and /3, which may be cylindrical, are provided. /'I are connected by any suitable means known to those skilled in the art. In the embodiment, these heat insulating sleeves and reinforcing members each have the same structure, but are shown with different reference numerals for convenience of explanation.

One heat insulating sleeve and λ reinforcing members at both ends
A thermal member is constructed. Each reinforcing member //~l is provided with a plurality of radial support ribs /S extending radially inward from its inner wall surface at equal intervals to form a wheel-shaped strength fitting. A plurality of support rods 16 to 19 having appropriate axial lengths are fixed to the center of the ribs IS by means such as welding.

The uppermost support rod 16 is not absolutely necessary.

The support rods It, /II; between the heat insulating sleeves 70 are connected to the connecting rod Coll by means of the connecting pins 20, and are configured to serve as seventh support means. The support rod 79 on the lowermost side, that is, on the tube sheet side, is welded to the ring rod 3 having radial support ribs 2 (shown in the figure) similar to the support ribs 15 described above at the support ribs, and is connected to the second support means. It consists of

Fixed in place on the outer surface of the tubesheet 2 is a flat support plate 21I, which is perforated with holes in a similar pattern to the tubesheet.
The ring ring 3 described above is inserted into this hole, and then the annular presser metal fitting, that is, the support member -! is screwed in and holds down Ringco 3. Therefore, the heat insulating tube IJ+buio corresponding to the tube sheet 1 is detachably fixed to the outer surface of the tube sheet 1 via the support plate 1.

Usually, a plurality of tube support plates are provided, and therefore there are the same number of heat insulating sleeves 9 corresponding to the tube support plates. The lengths of the support rods 4 to 19 and the connecting rod core are such that they can be installed and removed in a water chamber (not shown) on the outside of the tube plate 2, and that they can be installed and removed from the next fluid. The length is below that which does not cause vibration due to the flow inside the heat transfer tube. In order to sufficiently support the support rods 16 to 19 and the connecting rod 1 with the heat exchanger tube, metal ring rollers are installed as necessary on the support rods 16 to 19 and the connecting rod 21 (in the example, only the connecting rod 1 is installed). It can be attached by a radial support rib core in the middle of the. The support rib richness is the support rib l mentioned above! ,1
It is similar to ko.

In addition, in order to prevent the pressure loss in the heat transfer tube of the downstream fluid from becoming excessive, the diameters of the support rods 16 to 9 and the connecting rod ai should be set to such an extent that the cross-sectional area of the flow passages does not become excessively reduced, and that sufficient support is provided. Manufactured to dimensions that provide strength. And, in the part where there is a heat insulating sleeve that reduces the cross-sectional area of the flow path, the structure has virtually no support rod, minimizing the reduction in the cross-sectional area of the flow path,
Furthermore, the axial cross-sections of the support ribs 12- and -7 and the free end of the support rod are streamlined and shaped to reduce the road resistance as much as possible.

Next, the operation of the heat exchanger tube protection device of the present invention having the above-described configuration will be explained.

First, the support plate is fixed to the outer surface of the tube plate so that the related holes are aligned, and even if the assembly of parts other than the presser metal fitting S is performed outside the water chamber, The intermediate support rod/7, 1g and the connecting rod: 1 are connected with a connecting pin 20, so when inserting the device, the supporting rod or connecting rod can be assembled by appropriately rotating the connecting part in the water chamber. equipment can be entered through the icehouse manhole (not shown).

Putting the device in a water chamber in this way and putting state-of-the-art insulation sleeves inside the heat exchanger tubes that can cause damage due to corrosion or that have signs of damage? Push in first, and continue this process one after another to insert the reinforcing member 1 of the final insulation sleeve IO.
4! Radial support ribs! The bracket 3 provided on the support rod 19 welded to the support plate 19 is positioned so as to fit snugly into the hole in the support plate. At this time, since the spacing between the tube support plates and the various dimensions of the device are of course known, the device is configured such that the heat insulating sleeve corresponds to the tube support plate, and the heat insulating sleeve io corresponds to the tube support plate over the entire length of the straight pipe portion of the heat transfer tube. It is attached so as to correspond to the plate 2. After installing the device in this way, screw the presser metal fitting λda into the hole of the support plate to fix it.

During operation of a steam generator, in the normal heat exchanger tube section where the heat insulating sleeve does not cover, the high temperature primary fluid flowing in from the ice compartment side as shown by arrow j causes the secondary fluid outside the heat exchanger tube to leak onto the outer surface of the heat exchanger tube. evaporates violently. However, in the heat exchanger tube section surrounded by the tube support plate and tube plate, the heat insulating sleeves 9 and io connected by support rods and connecting rods are located, so compared to the normal heat exchanger tube section described above. As a result, the amount of heat transferred through the corresponding heat exchanger tube section becomes very small, and the temperature on the outer surface of the heat exchanger tube is almost equal to the temperature of the secondary fluid, so that evaporation on the outer surface of the heat exchanger tube does not substantially occur. If evaporation does not occur in the gaps t and tr, impurities in the secondary fluid will not be concentrated in these areas, and corrosion will not occur in the gaps.

For example, when inspecting the inner surface of a heat exchanger tube or inspecting the health of an apparatus, it is necessary to remove the apparatus, but this can be easily done by reversing the procedure described above.

As described above, in the heat exchanger tube protection device according to the embodiment of the present invention, the heat insulating sleeves, which are rotatably connected to each other by the support rod and the connecting rod, are arranged so as to correspond in position to the tube sheet and the tube support plate. In addition to being inserted into the heat exchanger tube, the heat insulating sleeve associated with the tube sheet is removably fixed to the outside surface of the tube sheet via the support plate on the outside surface of the tube sheet, so the following effects are achieved. can get.

l) Preventing the occurrence and progression of corrosion due to impurity concentration on the outer surface of the heat exchanger tube portion corresponding to the tube sheet and support plate.

e) Since the heat insulating sleeve is supported within the heat exchanger tube without any processing on the heat exchanger tube, it does not impair the reliability of the heat exchanger tube.

3) The device can be easily installed in the correct position, and
The device can be easily removed periodically for heat exchanger tube inspection and device health inspection, and accidents can be prevented.

In addition, in this embodiment, a ring having radial support ribs is provided at the fluid inlet opening of the heat exchanger tube, that is, the hole drilled in the support plate, so that even if the device is damaged, the outside of the heat exchanger tube remains intact. No damaged parts will be leaked. In addition, the axial cross section of the radial support ribs and the free ends of the support rods is streamlined, and there is virtually no support rod in the region corresponding to the heat insulating sleeve, so the pressure of the primary fluid in the heat exchanger tube is reduced. Losses can be kept to a minimum.

[Brief explanation of the drawing]

Fig. 1 is a partially omitted longitudinal sectional view showing a conventional heat transfer tube structure, Fig. 2 is a sectional view taken along the line ■-■ in Fig. 1, and Fig. 3 is a heat transfer/U protection device installed according to the present invention. Partially omitted cross-sectional views in the longitudinal direction showing heat exchanger tubes, Figures q to 6 are IV in Figure 3.
They are sectional views taken along the -N line, the ■-V line, and the ■-■ line.

Claims (1)

[Claims] A tube sheet, a porous tube support plate, and a plurality of heat exchanger tubes are provided, the ends of the heat exchanger tubes are inserted and fixed into the holes of the tube sheet, and the intermediate portions of the heat exchanger tubes are supported in the through support holes of the tube support plate. a plurality of cylindrical heat insulating members provided in the heat transfer tubes corresponding to the tube sheets and the tube support plates;
A support member that removably fixes a section member corresponding to the tube sheet to the ice chamber side of the tube sheet, a first support means that connects adjacent heat insulating members in a flexible manner, and a heat insulator corresponding to the tube sheet. a first support means connecting the member and the support member;
A heat exchanger tube protection device for a steam generator, characterized in that each heat insulating member is composed of a heat insulating sleeve at the center and wheel-shaped strength fittings at the ends.