JPS5970813A - Steam turbine expansion joint retainer ring - Google Patents

Abstract

PURPOSE:To prevent separation of an expansion pipe fitting and thereby enhance the safety by employing a divided retainer ring, in which a lock ring part and a retainer ring part are embodied in a single solid construction, and by allowing the retainer ring itself to work also with joining function. CONSTITUTION:A retainer ring 13 has a profile including a lock ring so as to be fitted in a groove 10, being divided in a plurality of segmented pieces, where the two ends of any one or more of those segments 14 are parallel. Fixation of each segment 14 is ensured with bolts 9. When steam Sa flows in the expansion pipe fitting, thermal expansion phenomena arise in the expansion fitting 4, sealings 5a, 5b, retainer ring 13 and external wheel chamber 1 in a sequence as named here. If an alloy with large coefficient of thermal expansion is used for the retainer ring 13, the part makes larger expansion compared with the other parts, and the wedge effect given by the angle D formed by the divisional surfaces of retainer ring 13 will ensure fixation of the ring by means of strong contact to the side of the external wheel chamber, so that separation is prevented and the safety enhanced.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to a steam turbine expansion joint structure, and in particular, to prevent a seal ring from falling off from an insertion site, and a retainer.
The present invention relates to a retainer ring structure that can prevent the ring itself from falling off.

[Prior art]

Steam turbines manufactured in recent years have become larger in size, and
It has come to be used under high temperature and high pressure steam conditions. The structure of the turbine body is complicated, and the casing is generally double-layered: an external casing and an internal casing. For this reason, the role of the expansion pipe joint is very important in introducing steam from the outside of the turbine into the inner casing while keeping the outer casing and the inner casing airtight. However, because the retainer ring, which is an important component of this expansion joint, is fixed only by the constriction applied to the passenger compartment, the retainer ring becomes loose due to harsh operation of the turbine, and the retainer ring becomes loose. There is a concern that it may fall off. The following describes an example of the external compartment of a main steam expansion pipe joint.

FIG. 1 is a structural diagram of a casing in a high and intermediate pressure section of a steam turbine. FIG. 2 is a detailed view of the section ■ in FIG. 1.

Figure 3 is a view of the expansion pipe joint from the ■ direction in Figure 2.
FIG. 2 is a plan view of a retainer ring and a lock ring.

The telescopic pipe 4 is a steam introduction pipe for guiding the steam Sa from the external compartment 1 to the nozzle box 3 assembled in the internal compartment, bypassing the internal compartment 2. A gap Qa is provided between the expansion tube 4 and the outer casing 1 to absorb the difference in thermal expansion between the inner and outer casings and the expansion tube, which is generated due to steam heat during operation of the turbine. During this time, in order to seal the leaked steam Sb from 1jJGa, between the external compartment 1 and the telescopic pipe 4, a seal ring 5a is connected to the telescopic pipe 4, and a seal ring 5b is connected to the external compartment 1, respectively. Multiple rows are assembled alternately. This seal ring 5a
, 5b from falling off is the lock ring 6. The entire lock ring 6 is divided into a plurality of parts as shown in FIG. This is because it is inserted into the groove 10 provided in the external compartment 1 for assembly. Further, a gap Gb is provided between the lock ring 6 and the seal ring 5b to absorb the difference in thermal expansion between the seal rings 5a, 5b and the external compartment 1. In this case, the difference in thermal expansion of the seal ring 5a is close to that of steam at the start of operation of the turbine.

This occurs because 5b expands first.

Therefore, during normal operation of the turbine, no difference in thermal expansion occurs, so the gap Gb remains.

In this way, although the lock ring 6 is inserted into the groove 10, it is in a very unstable state because it is a divided body with a gap. Therefore, it is necessary to support it with the retainer ring 7 to prevent it from falling off during assembly and disassembly. The retainer ring 7 is generally fixed by means of a shark 11 in the outer compartment 1.

The biggest problem with the expansion joint structure is that the seal rings 5a, 5b, lock song 6, and retainer ring 7, which have no supporting functions, must be supported only by the retainer 11 of the external compartment 1. It is. Therefore, the difference between the pressure of steam Sa generated during turbine operation and the steam pressure in the inner and outer compartment space 12 is about 200 atg, and the seal ring 5a,
5b, the o-ring 6 and the retainer ring 7, the total weight of the o-ring 6 and the retainer ring 7 is applied as a repeated load by the turbine motion.
Finally, the forging 11 is loosened and the retainer ring 7 falls off.

As a countermeasure to this phenomenon, increase the amount of coins or use a retainer.
Although methods such as supporting the ring 7 with a fixing pin 8 have been taken, the phenomenon of loosening of the weakened portion cannot be completely eliminated. In the unlikely event that the retainer ring falls off during turbine operation, the lock ring and seal ring may fall off, resulting in a decrease in turbine operating efficiency and damage to the turbine due to the lock ring flying off, leading to a serious accident. There is an urgent need to establish a reliable method for fixing the chainer ring.

[@Ming's purpose]

An object of the present invention is to provide a chainer ring that prevents it from falling off and improves safety and reliability.

[Summary of the invention]

Conventionally, the retainer ring was fixed using a single-chambered retainer 6, which made it unstable for imaging and pressure, but the present invention uses an austenite alloy with a large coefficient of thermal expansion. By adopting a split type retainer ring that has a lock ring part and a chainer ring part as one unit, the retainer ring itself can have a fixing function and prevent the retainer ring from falling off.
We aimed to improve safety.

[Embodiments of the invention]

An embodiment of the present invention is shown in FIG. 4, taking as an example the external compartment of a main steam telescopic V-joint. FIG. 5 is a view of the expansion pipe joint viewed from the direction ``■'' in FIG. 4, and shows the planar shape of the retainer ring according to the present invention.

The retainer ring 13 is a seal ring 5a.

5b has a cross-sectional shape that includes the lock ring 6 in order to be inserted into the groove 10 of the external compartment 1 provided to ensure the locking effect. Further, in order to enable insertion and assembly into the groove 10 in a ring shape, it is divided into a plurality of parts as shown in FIG. In addition, it may be divided or the chainer ring 13
The end faces of one or more of the segments 140 are parallel. This is because the retainer ring 13 is assembled last. Further, the fixation of the segment 14 is ensured by the bolt 9.

When steam Sa flows into the expansion pipe joint assembled in this manner, the expansion tube 4, the seal ring 5, the retainer ring 13, and the external casing 1 exhibit a thermal expansion phenomenon due to the heat of the steam in this order. What should be noted here is that the material of the retainer ring 13 has a large coefficient of thermal expansion, for example,
is to use an austenitic alloy. As a result,
During operation of the turbine, retainer ring 13 undergoes significantly greater thermal expansion than other components made from ferrite alloys. This large thermal expansion causes the retainer ring 13 to be brought into close contact with the outside vehicle compartment side and fixed thereto due to the wedge effect of the angle of the split surface of the chainer ring 13, as shown in FIG.

〔Effect of the invention〕

According to the present invention, it is possible to securely fix the chainer ring, and there is no need to fix the retainer ring by plating, so there is no need to process a matching groove in the external compartment. moreover,
It can prevent artificial damage to the external compartment. Furthermore, since no lock ring is required, there is an effect of reducing the number of parts.

[Brief explanation of drawings]

Figure 1 is a vertical cross-sectional view showing the configuration of the high and intermediate pressure casing of a steam turbine, Figure 2 is an enlarged view of the ■ section in Figure 1 and a detailed view of the expansion joint, and Figure 3 is in the ■ direction of Figure 2. FIG. 4 is a sectional view of the expansion pipe joint of the present invention, and FIG. 5 is a plan view of the retainer ring as viewed from the direction ① of FIG. 4. 1... External compartment, 2... Internal compartment, 3... Nozzle box, 4... Telescopic W, s a... Seal ring, 5b... Seal ring, 6... Lock ring, 7
... Retainer ring, 8... Fixed bottle, 9...
Bolt, 10... Groove, 11... Scissor, 12... Inner and outer compartment space, 13... Retainer ring, 14...
Segment, Sa...steam, sb...leakage steam, Q
a...Gap, Gb...Gap, D...22nd 10th Figure 3

Claims (1)

[Claims] (1) In an expansion joint structure for a conduit connecting multiple steam chambers of a steam turbine, a lock ring for preventing a seal ring from falling off and a retainer ring are integrated into one. Glued chainer rings for steam turbine expansion joints. 2. A joint ring for a steam turbine expansion pipe joint according to claim 1, characterized in that the retainer ring is divided into a plurality of segments, and both end faces of the segments are made parallel. 3. A steel ring for a steam turbine expansion joint according to claim 1, characterized in that the material of the retainer ring is austenite alloy having a large coefficient of thermal expansion.