JPS624524B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a fluid inlet pipe for a steam or gas fluid turbine.

A steam turbine to which the fluid introduction pipe of the present invention is applied will be explained. Figure 1 is a schematic system diagram of a thermal power generation plant, where 1a is a boiler and 1b is a boiler.
is a reheater, 2 is a high-pressure turbine, 3 is an intermediate-pressure turbine, 4a is a first low-pressure turbine, 4b is a second low-pressure turbine, 5 is a generator, 6 is a condenser, and the steam flow is indicated by an arrow. It is shown in The steam generated in the boiler 1a is sent to a high pressure turbine 2, an intermediate pressure turbine 3,
In the first and second low-pressure turbines 4a and 4b, the thermal energy of the steam is converted into kinetic energy, which becomes the driving force for driving the generator 5. Steam flows into each turbine through a high-pressure steam introduction pipe 7a, an intermediate-pressure steam introduction pipe 7b, and a crossover pipe 8, and after energy conversion, it is discharged from low-pressure turbines 4a and 4b, and is converted into water by a condenser 6. The steam is then returned to the boiler 1a, where it becomes steam again and circulates within the plant. However, the steam contains a large number of fine solid particles that can damage the components of each turbine. In particular, the attack on the diaphragm nozzle blades is significant.
These fine solid particles are contained in the boiler 1a and the reheater 1b.
This is oxidized scale that has formed on the inner surface of austenitic stainless steel pipes commonly used for boilers when exposed to high-temperature, high-pressure steam for a long period of time, and has peeled off and scattered due to temperature changes caused by boiler startup and shutdown. be. Although various studies have been conducted on the formation and peeling of oxide scale, no effective method for preventing it has yet been revealed. Furthermore, it is considered that it is almost impossible to completely prevent the formation of oxide scale.

FIG. 2 shows the curved pipe portions of a conventional high-pressure steam introduction pipe and an intermediate-pressure introduction pipe. That is, in the figure, the bent pipe section is a straight pipe 9 and an elbow 10 connected by welding, and the inner surface is finished smoothly to prevent turbulence in the flow of steam. The steam flow velocity in the steam introduction pipe reaches approximately 55 m/sec in the power plant shown in Figure 1, and the scale 11 that comes from the boiler and reheater with the steam has a higher specific gravity than the steam, so it passes through the elbow 10. It cannot follow the flow of the steam 12 when the steam 12 is moving, collides with the elbow 10, breaks into fine solid particles 13, flows into the turbine, and damages internal components.

FIG. 3 shows a crossover pipe connecting the intermediate pressure turbine and each low pressure turbine. The crossover pipe includes pipes 14a, 14b, 14c, elbow 15,
The balance tubes 16 each have bellows 17a in the middle,
17b, 17c, and 17d are sandwiched and connected by welding or tightening with bolts. Fine solid particles 1 discharged from the intermediate pressure turbine 3
Since the internal area of the pipe 14a and the pipe 14c is approximately 2:1, the steam 12 containing the
will flow in at a rate equal to. The steam flow rate in the pipe is approximately
The speed has reached 45m/sec. However, the fine solid particles 13, which have a much larger specific gravity than the steam,
When steam flows into the first low-pressure turbine 4a, the majority of the steam cannot keep up with the flow of steam and ends up flowing into the second low-pressure turbine 4b.
This is also clear from the phenomenon that the diaphragm nozzle blades in the second low-pressure turbine 4b have a greater amount of contact than the diaphragm nozzle blades in the first low-pressure turbine 4a.

FIG. 4 shows a state in which fine solid particles 13 contained in steam 12 are colliding with the diaphragm nozzle blade 19, and FIG. Part 2
It shows 0.

As described above, conventionally, in high/medium pressure steam introduction pipes and crossover pipes, fine solid particles contained in steam are not restricted in any way. There was a risk that the steam would flow into each turbine, damaging internal components such as the diaphragm nozzle blades, and possibly causing a major accident.

Although the above explanation has been given using a steam turbine as an example, the same applies to gas turbines, and in the case of multistage turbines, the same applies to any of the fluid introduction pipes connected to the inlets of high, medium, and low stage pressure turbines. I can say something.

An object of the present invention is to prevent fine solid particles from flowing into each turbine, which is a drawback of the conventional method.
The objective is to provide a safe and reliable fluid introduction pipe.

In order to achieve this object, the present invention provides an opening provided in a tube wall including a portion having the maximum radius of curvature of a curved tube section, and communicating with the curved tube section through the opening, and a fluid The pipe is characterized in that it is equipped with a separation chamber for separating and storing fine solid particles therein, and that the opening is located downstream of the center point of the upstream pipe entrance of the curved pipe part. be.

The details of the present invention will be explained below with reference to the drawings.

6 and 7 show a fluid introduction pipe having a separation chamber for separating and storing fine solid particles according to the present invention, and exemplify the case where the pipe is connected to a steam turbine inlet.

FIG. 6 shows a structure for separating and storing fine fixed particles in a high/medium pressure steam introduction pipe. An elbow 10a, which is a bent pipe portion, is connected and fixed by a bolt 22 between a straight pipe 9a and a straight pipe 9b that are arranged perpendicularly to each other. The elbow 10a is formed, for example, by casting, and the opening 21 absorbs the steam flowing from the upstream side (upper side in the figure) of the tube wall, that is, the part of the elbow 10a having the maximum radius of curvature, in other words, the steam. Side edges 21a and 21b, which are located on the longest so-called outer wall side of the passage and are opposed to each other perpendicular to the direction of steam flow, are located a distance A toward the downstream from the center of the upstream pipe inlet. The fine solid particle separation chamber 23 has a substantially cylindrical shape, is arranged along the upstream steam inflow direction, and has a spiral tongue-like body that has the role of guiding the fine solid particles 13 to the back of the separation chamber. An inner tube 24 having a diameter is inserted. Separation chamber 13 is fixed to elbow 10a via bolt 25. Furthermore, a manhole cover 26 is fixed to the end of the separation chamber 23 via bolts 27 for the purpose of internal inspection during periodic inspections and for evacuation of fine solid particles, and is normally kept completely sealed. There is.

Steam 12 containing fine solid particles 13 is passed through pipe 9a.
Approximately from the side (upstream side) to the pipe 9b side (downstream side)
It is flowing with a velocity of 55 m/s. However, as described above, the fine solid particles 13, which have a much higher specific gravity than the steam 12, flow along the outer wall of the elbow 10a when passing through the elbow 10a, so they pass through the opening 21 and are separated into fine solid particles. room 2
It is contained while scattering inside 3. Moreover, elbow 1
Since the steam pressure in 0a and the steam pressure in the fine solid particle separation chamber 23 are equal, the pressure of the steam trying to enter the separation chamber and the pressure of the steam inside the separation chamber trying to push it back is Due to the balance near 21, a vortex 28 is generated and this acts as a kind of curtain, which has the effect of preventing the backflow of the fine solid particles 13 once accommodated in the separation chamber 23, and the fine solid particles 13 are separated. It will be deposited in the chamber 23. In addition, the fine solid particles 13 are transferred to the steam 1
In order to collect effectively without preventing the flow of 2.
Preferably, the opening 21 is offset downstream by a distance A from the center of the upstream pipe inlet. In this embodiment, the distance A is set equal to the radius of the elbow 10a, so that most of the fine solid particles 13 floating in the straight pipe 9a gather at the opening 21 when they collide with the outer wall of the elbow. Also, one side edge 21a of the opening 21 is a distance B from the center of the downstream pipe of the elbow 10a.
However, if this distance B is too small, the flow of steam 12 will be prevented, which is not preferable.

FIG. 7 shows a state in which the structure for separating and housing fine solid particles is applied to a crossover pipe, and FIG. 8 is an enlarged view of the X section in FIG. 7. Third
The difference from the conventional crossover pipe shown in the figure is that the elbow 15 connected to the inlet of the second low pressure turbine 4b is provided with an opening 21 in the form of a notch in the outer wall, and the notch has a truncated part. This is the point where a conical empty spike 29 is formed. Also, the opening 21
A deflector plate 30 is formed on the side edge of the low-pressure turbine inlet side to project toward the head side of the empty spike 29.

Therefore, the microstructured solid particles 13 that have flowed together with the steam 12 through the crossover tube are scattered and accommodated in the balance tube 16 from the opening 21 along the outer wall of the spike 29. Moreover, with the deflection plate 30,
Fine solid particles smoothly fly into the balance tube,
And it is designed to prevent backflow. It is also desirable to provide a manhole 31 in the lower part of the balance pipe 16 to enable internal inspection and discharge of fine solid particles accumulated inside the turbine when the turbine is not operating.

In this case as well, the diagram clearly shows that the opening 21 is formed at a position offset toward the downstream side from the inside of the upstream pipe (reference numeral C in the diagram).

According to the present invention, many fine solid particles can be effectively and reliably separated and contained, so damage to components within the turbine can be reduced.
Turbine reliability can be improved.

[Brief explanation of the drawing]

Figure 1 is a schematic diagram of a thermal power plant;
The figure is a cross-sectional view showing a conventional high-medium pressure steam introduction pipe.
The figure is a cross-sectional view showing a conventional crossover pipe.
5 and 5 are views for explaining corrosion of nozzle blades, FIGS. 6 and 7 are cross-sectional views showing the high and intermediate pressure steam introduction pipe and crossover pipe of the present invention, and FIG. FIG. 10a...Elbow, 12...Steam, 13...Fine solid particles, 21...Opening, 23...Fine solid particle separation chamber.

Claims (1)

[Claims] 1. In a fluid introduction pipe that is connected to the fluid turbine inlet and has a curved pipe part in the middle, an opening provided in the pipe wall including the part having the maximum radius of curvature of the curved pipe part, and the a separation chamber that communicates with the curved pipe section and separates and accommodates fine solid particles in the fluid, and the opening is located downstream of the center point of the upstream pipe inlet of the curved pipe section. A fluid introduction tube characterized in that: