JPS6090902A - Crossover pipe - 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 [Field of Application of the Invention] The present invention relates to a crossover pipe for a steam turbine, and in particular,
This article concerns the structure of a cross-over tube installed on the back side of the manhole elbow that enters the pressure balance chamber.

[Background of the invention]

The crossover pipe is a pipe that introduces the steam that has finished working in the intermediate pressure turbine to the low pressure turbine, but in general, the relative thermal expansion between the intermediate pressure casing and the low pressure casing due to the high temperature of the intermediate pressure exhaust,
The contraction is completely absorbed by an expansion joint installed in the middle of the crossover pipe, that is, two bellows, so that no unreasonable reaction force is applied to the valley single chamber during operation.

1 to 3 illustrate the principle of thermal expansion absorption.

Is the bellows in figure 1? In the case of a simple pipe that is not used, of course it cannot absorb thermal expansion and contraction.

Therefore, a large reaction force due to thermal expansion is applied to each of the compartments.

However, the reaction forces 10F and -F due to the internal steam pressure PK are balanced inside the vibrator.

Q and R each indicate the flow direction of steam.

In Fig. 2, one bellows LK is inserted, which absorbs thermal expansion and contraction, but reaction forces +F and -F due to internal steam pressure P are applied to each compartment from 72 inches at both ends.

Figure 3 shows two bellows L and bellows 2, which are used to completely absorb thermal expansion and contraction, and at the same time balance the reaction forces +F and -Fk inside the vibrator due to internal pressure. This is the structure generally adopted for glue loss over saving.

That is, in this structure, the internal steam pressure P is communicated with the pressure balance chamber 7 consisting of the pipe 5, the bellows 2, and the end plate 6 through the balance hole 4 provided in the elbow 3, and the reaction forces 1 and -F due to the internal pressure are 1 It is balanced inside the pipe via the rigid body member 8.

By doing this, it is possible to completely eliminate the reaction force applied to the single chamber under all operating conditions.

A manhole according to the prior art was installed in a crossover pipe according to the JJA method, as shown in FIG. 4.

In FIG. 4, a crossover pipe 12 that completely communicates between the medium pressure casing 9 and the low pressure casing 10 is composed of a pipe 11, a bellows 11, an elbow 3, a pressure balance chamber 7, and a wrapper 8. A manhole 13 is installed on the mirror plate 6.

An enlarged view of the vicinity of the pressure balance chamber 7 in FIG. 4 is shown in FIG.

A bellows protection inner cylinder 14 is installed on the inner surface of the bellows 2 (L).

Now, for example, on an occasion such as a regular inspection, the crossover pipe 12
In order to disassemble the bellows 2 and inspect the inside of the bellows 2, it is necessary to enter the pressure balance chamber 7 through the manhole 13 and remove, move or cut part or all of the bellows protective inner cylinder 14.

The conventional manhole 13 installed for this work is shown in Fig. 6 and its enlarged view in Fig. 7.
Manhole pipe m attached to head plate 6 by welding
i 5, gasket 16, manhole cover 17. It consists of a bolt 18 and a lock washer 19.

In such a conventional structure, as is clear from FIG. 3, the end plate 6 is a pressure-resistant part that receives a reaction force of 10 Fk due to the internal steam pressure P, and therefore the manhole nozzle 15i attached thereto, as well as the gasket 16. Manhole cover 1
7. Parts such as Holt 18 are also pressure-resistant parts.

Care must be taken in all processes such as design, strength calculation and manufacturing of these parts, welding work to attach the nozzle, assembly work, and pressure resistance test. was spending.

The size of the manhole naturally provides the necessary minimum abundance of water, and in general, the roundness of the corner of the head plate 6 is
There is also a restriction that it is undesirable for the outer diameter of the nozzle stub to overlap the Q inner radius Rk, so the outer diameter of the manhole nozzle 15 is usually
Since it requires about 700 mm, a manhole cannot be installed if the outside diameter of the waste plate is small, and therefore the outside diameter of the cross oats is small.

[Purpose of the invention]

An object of the present invention is to provide a cross-over structure with a new type of manhole pipe.

[Summary of the invention]

The main point of this invention is the manhole? Installation location Avoid the metal plate part and install it on the back side of the elbow in the non-pressure resistant part.

[Implementation sequence of the invention]

An embodiment of the present invention will now be described with reference to FIGS. 8 to 10.

In FIG. 8, the major difference from the prior art is that the 20 manholes are installed not on the mirror plate 6 but on the back side of the elbow 3.

That is, as shown in the enlarged view of Fig. 9 and Fig. 1O, the back side of the elbow 3 is cut out to the required size, and the manhole cover 21, which is located in the middle of the balance hole 4nl, is attached to the plurality of stoppers 22 with bolts 23. , a structure in which a manhole 20 is installed.

The stopper 22 is attached by welding to the outer periphery of the hole cut out in the back ai of the elbow 3 as shown in FIG. 1θ.

The manhole cover 21 is economical because it can be obtained by hollowing out the back side of the elbow 3 and can be used with only slight processing and maintenance.

The head of the bolt 23 is tack-welded all around to prevent it from loosening.

When entering the pressure balance chamber 7, chip off the tack welds on the heads of the bolts 23 and remove the 23 bolts.
Remove manhole cover 21f and go inside.

As is clear from Fig. 3, since the elbow 3 is provided with a balance hole and is a non-pressure-resistant part, the work of installing the manhole 20 (f-) therein is much easier than in the prior art. be.

In addition, since the present invention does not require a manhole nozzle stand, a new 20-karat gold manhole can be installed on crossover pipes with small pipe diameters, which is functionally comparable to the conventional manhole 13 installed on the end plate. It becomes possible to do so.

In addition, when the manhole 1375j of the conventional structure is installed in the end plate 6, in order to further improve various work efficiency inside the pressure balance chamber 7, the manhole 20 according to the present invention is installed in the elbow 3. It is effective to add or install it.

〔Effect of the invention〕

According to the present invention, the number of parts constituting the manhole hold can be greatly reduced, and since the manhole is installed in a non-pressure-resistant part, the labor for the entire process from design to manufacturing to inspection can be reduced by almost half, making it economical. Ruru.

Moreover, it becomes possible to install a manhole even in a crossover pipe having a relatively small pipe diameter.

[Brief explanation of the drawing]

Figures 1 to 3 are longitudinal cross-sectional views showing the principle of thermal expansion absorption of crossover pipes, Figure 4 is a vertical cross-sectional view showing the overall structure of a conventional crossover pipe when installed, and Figure 5 is Figure 4. Fig. 6 is an enlarged longitudinal sectional view of the vicinity of the pressure balance chamber in Fig. 5, Fig. 7 is a side view of Fig. 6, and Fig. 8 is an enlarged longitudinal sectional view of the manhole installation part in Fig. 5. A vertical cross-sectional view of one embodiment,
FIG. 9 is an enlarged vertical sectional view of the manhole installation part in FIG. 8, and FIG. 1O is a view taken in the direction of the X arrow in FIG. 9. 3...Elbow, 4n...Balance hole, 12...
・Crossover pipe, 20... Manhole, 21...
Manpo 1st mouth 2nd country 4th concave

Claims (1)

[Scope of Claims] 1. In a crossover pipe for a steam turbine having a pressure balance chamber consisting of a pipe, a bellows-type expansion joint, and a head plate, the head plate is located at a position facing from the inner 1) 11, and is located at a position facing from the front and distribution pressure chambers, A crossover pipe characterized by a manhole installed on the back side of the elbow that forms the other wall forming the chamber.