JPH08151993A - Burrell casing type turbine pump - Google Patents

Abstract

(57) [Summary] [Structure] The intermediate stage water extraction chamber in which the swirling flow flows is eliminated, the outer casing 1 and the inner casing after the water extraction stage are fitted to each other on the inner and outer peripheral surfaces, and sealed by the O-ring 13, and further the backup ring. The structure of 14 is designed to prevent the O-ring 13 from being caught. [Effect] By reducing the inner and outer diameters of the outer casing and supporting the inner casing at three points, vibration of the inner casing can be suppressed, and cost and noise can be reduced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a barrel type turbine pump such as a boiler feed pump for a thermal power plant or a reactor feed pump for a nuclear power plant, and more particularly to a barrel casing turbine having an intermediate stage extraction chamber. Regarding pumps.

[0002]

2. Description of the Related Art A barrel casing type turbine pump is disclosed in, for example, Japanese Utility Model Publication No. 55-46759, wherein a water return vane, a stage and a guide vane having a rectifying action are provided in an outer casing called a barrel. And an outer casing connected by a casing cover that suppresses the outflow of high-pressure water from the discharge chamber to the outside.

The annular gap between the inner and outer casings forms two chambers, an intermediate-stage drawing chamber (reheater spray drawing chamber) having a drawing stage pressure and a high-pressure discharging chamber, and is defined by a contact surface portion between the inner casing and the outer casing in a direction perpendicular to the axis. It is divided. In addition, the contact surface is in metal contact with the high pressure water in the discharge chamber acting on the inner casing, thereby fulfilling the sealing function.

[0004]

The above structure has a contact sealing surface in the direction perpendicular to the axis in order to partition the two chambers, the intermediate-stage drawing chamber having a drawing-stage pressure and the discharge chamber having a high pressure, and the intermediate-stage drawing water is provided. The stage that separates the chamber and the high-pressure water discharge chamber must have a shape different from the other stages and a stage outer diameter larger than that of the other stages. Further, since the outer casing is in contact with the stage in a direction perpendicular to the axis, it is necessary to provide a large step on the inner diameter of the outer casing, which corresponds to the intermediate water extraction chamber and the discharge chamber seal portion. Therefore, the inner diameter of the discharge portion of the outer casing increases, and the outer diameter of the outer casing also increases.

On the other hand, the fluid to which the dynamic pressure is applied by the impeller of each stage is recovered by the guide vane to a static pressure, is rectified by the water return vane, and is sent to the impeller of the next stage. By repeating this process, the high-pressure water is pressure-fed to the downstream side from the discharge port. In the pressure rising process, the fluid flowing out from the outlet of the impeller rotating at high speed interferes with the leading edge of the guide vane and vibrates the entire guide vane. This vibration occurs in all stages of the inner casing, and this vibration also causes the outer casing to vibrate, which causes noise in the barrel casing turbine pump.

It is an object of the present invention to provide a barrel pump of the barrel type which achieves the same function as the conventional one, but which reduces cost and noise.

[0007]

To achieve the above object, the present invention comprises an outer casing having a suction port and a discharge chamber, and an inner casing inside the outer casing. And a discharge chamber of a pressure higher than the fluid pressure, a water extraction chamber filled with an intermediate pressure fluid, and a stage of a water extraction stage for sending the fluid of the intermediate pressure to the water extraction chamber. As a method of partitioning the chamber and the discharge chamber, the outer casing and the inner casing are fitted to each other on the inner and outer peripheral surfaces, and an O-ring and a backup ring are provided to seal the intermediate water extraction chamber and the discharge chamber.

[0008]

According to the present invention, the conventional seal contact surface for sealing the intermediate water extraction chamber and the discharge chamber in the direction perpendicular to the axis is eliminated, and the inner and outer circumferences of the outer casing and the inner casing are replaced with the seal contact surface in the direction perpendicular to the axis. By providing a sealing surface on the fitting surface, the outer diameter of the casing can be reduced, and by providing an O-ring and a backup ring, high-pressure water in the discharge chamber can be guided to the intermediate-stage drawing chamber. Can be completely sealed. Further, in addition to the two-point support of both ends of the inner casing, since the outer casing, which is a seal portion of the intermediate-stage drawing chamber and the discharge chamber, and the inner and outer peripheral surfaces of the inner casing are fitted together, a supporting portion is formed in the middle portion of the inner casing, Vibration transmitted from the inner casing can be reduced.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIG.

FIG. 1 shows a barrel type multi-stage turbine pump.
It is sectional drawing of one Example which applied this invention to (double copper casing type turbine pump). The pump has an inner casing 5, which is composed of a water return vane 2, a stage 3 and a guide vane 4 having a rectifying function, arranged in an outer casing 1 called a barrel casing. The shaft 6 and the impeller 7 are attached. The outer casing 5 is connected by a casing cover 7 that suppresses the outflow of the high pressure water from the discharge chamber 6. The annular gap between the inner and outer casings is provided with two chambers, a water extraction chamber 9 having a pressure of the water extraction stage 8 and a discharge chamber 10 having a high pressure, and a fitting surface 12 provided on the outer peripheral surface of the stage 3 after the water extraction stage and the inner peripheral surface of the outer casing. The O-ring 13 interposed between the two seals seals the two chambers, that is, the water drawing chamber 9 at the water drawing stage pressure and the high pressure discharge chamber 6. Reference numeral 8 is a water extraction stage discharge port for sending the water extracted from the water extraction chamber 9 to the reheater under pressure.

The extraction stage will be described by taking a thermal power generation system as an example. In this system, a reheater is installed in the boiler in order to improve the thermal efficiency of the plant due to steam conditions and prevent blade damage and loss increase of the main steam turbine due to the increase in the wetness of the steam. In recent years, thermal power generation systems are not only becoming more efficient and larger in capacity due to the diversification of demand, but also being forced to undergo rapid load fluctuations so as to be able to follow daily fluctuations in power demand. As a result, it is necessary to optimally control the steam condition of the reheater in order to improve the thermal efficiency of the plant, and it is possible to satisfy the required temperature and pressure to secure the required amount of water, and to extract water from an economical extraction point. Will be done. To satisfy these conditions, water is extracted from the intermediate stage of the multi-stage turbine pump.

For the above reasons, the extracted water is sent from the extraction chamber 9 to the reheater when the load changes and when the plant starts / stops, and is used for heating or cooling the reheated steam to control the steam condition.

Further, as the capacity of the thermal power generation system increases, the capacity of the pump used also tends to increase. In a multi-stage turbine pump in which the operating pressure condition is high, the pressure generating portion is covered with a thick barrel barrel. A casing type multi-stage turbine pump is suitable.

Outer casing 1 and stage 3 in FIG.
It is necessary to completely seal the feed water whose handling liquid temperature is about 200 ° C. or less, and the silicon-based rubber packing is suitable for the O-ring 13 interposed between and. The chemical structure of the silicon-based rubber is a linear polymer having a siloxane bond as a skeleton and an organic group bonded to Si therein. In addition, by arranging the backup ring 14 on the suction port side of the O-ring 13 as shown in the enlarged view of the seal portion of the outer casing 1 and the stage 3, when assembling the pump or from the discharge chamber 6 to the intermediate stage water extraction chamber. When the O-ring 13 moves due to high-pressure water flowing in nine directions, it is possible to prevent the outer peripheral surface of the stage 3 and the inner peripheral surface of the outer casing 1 from being caught in a minute gap in the fitting surface 12. It has a structure that allows it.

An example of a conventional technique relating to a barrel barrel type turbine pump is shown in FIGS. Figure 2
Fig. 3 shows a cross-sectional structure of a boiler feed pump used in a thermal power generation facility, and Fig. 3 is a cross-sectional view near the discharge part.

The outer diameter of the inner casing 5 from the next stage to the final stage of the water drawing stage is designed to have a necessary wall pressure in consideration of only the pump discharge pressure. In order to secure the sealing function of the portion 10, it is necessary to make the outer diameter of the inner casing of the next stage of the water extraction stage large as shown in this figure, and the wooden mold at the time of casting must be changed to another one. According to the present embodiment, the outer diameter of the stage 3 subsequent to the water extraction stage can be made the same as that from the first stage to the water extraction stage, and the wooden pattern can be shared, so that it can be manufactured. It will be easy.

Further, since the outer diameter of the stage 3 next to the water extraction stage can be made smaller than that of the conventional one, the inner diameter and outer diameter of the outer casing, and the casing cover 7 in accordance therewith.
Since the outer diameter of the material is also small, the material cost can be reduced.

Further, the outer diameters of all the stages 3 are the same,
Immediately after exiting the water extraction hole of stage 3 of the water extraction stage, the same number of water extraction holes of stage 3 of the water extraction stage and the water extraction holes of outer casing 1 are provided in the same radial direction, and the intermediate water extraction chamber 9 in which the conventional swirling flow flows is not provided. By passing through the water extraction hole of the outer casing 1 and discharged from the water extraction port 8 to the outside of the pump, it is possible to prevent erosion due to the swirling flow in the water extraction chamber 9 and to reduce the flow loss of the water extraction. In addition to this, by eliminating the conventional intermediate stage water extraction chamber 9, it is possible to reduce the inner and outer diameters of the outer casing 1 before the water extraction stage, which also reduces the material cost.

In the present invention, it is stated that the outer diameters of all the stages 3 are the same. However, in consideration of the assemblability, as shown in FIG. 1, the outer diameter of the stage 3 before the water drawing stage is the same as that after the water drawing stage. The inner diameter of the inner casing 5 is slightly smaller than the outer diameter of the stage 3 (the outer diameter of the stage before the water drawing stage and the inner diameter of the outer casing 1 are preferably several mm), and the inner casing 5 is assembled into the outer casing 1 and vice versa. It is desirable to make it easier to extract.

Next, another operation will be described. In the barrel type turbine pump taken up in the present invention, a dynamic pressure is applied to the fluid by the high speed rotation of the rotary shaft 6 and the impeller 7, and the fluid to which the dynamic pressure is applied is statically recovered by the guide vanes 4. Is rectified by the water return vane 2 and sent to the next stage impeller 7. By repeating this, the fluid is pumped to the discharge port 12, and the pressure of the fluid is increased. In this pressurizing process, the fluid flowing out from the outlet of the impeller 7 rotating at high speed interferes with the front edge of the guide vane 4 and vibrates the guide vane 4. The vibration due to the vibration is generated in all stages of the guide vanes 4, and the vibration propagates to the stages 3 of the respective stages to vibrate the entire inner casing 5. these,
In addition to the conventional two-point support of the first stage 3 and the mating surface 11 of the outer casing and the final stage guide vanes 4 and the mating portion 15 of the casing cover 7, in the present invention, the outer peripheral surface of the inner casing and the outer casing after the drawing stage are used. It is supported at three points on the fitting surface 12 with the inner peripheral surface. As described above, the radial movement of the intermediate portion of the inner casing 5 is restrained and the vibration of the entire inner casing 5 is suppressed, so that the noise of the entire pump can be reduced.

[0021]

According to the present invention, by reducing the outer diameter of the outer casing and suppressing the vibration of the inner casing,
It is possible to provide a barrel casing type turbine pump having a cost reduction and noise reduction structure.

[Brief description of drawings]

FIG. 1 is a sectional view of an embodiment in which the present invention is applied to a barrel casing type turbine pump.

FIG. 2 is a conventional cross-sectional view of a boiler feed pump used in a thermal power generation facility.

FIG. 3 is a cross-sectional view of the vicinity of the discharge portion of FIG.

[Explanation of symbols]

1 ... Outer casing, 2 ... Water return blade, 3 ... Stage, 4
... Guide vanes, 6 ... Discharge chamber, 11, 15 ... Mating surface, 12 ...
Mating surface, 13 ... O-ring, 14 ... Backup ring.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Takuya Fujii Inventor Takuya Fujii, 603 Kandachi-cho, Tsuchiura, Ibaraki Pref.

Claims (1)

[Claims] Claim: What is claimed is: 1. An outer casing having a suction port and a discharge chamber, and an inner casing inside the outer casing. The fluid pressure of the suction port and the discharge chamber having a pressure higher than the fluid pressure. In a barrel type turbine pump provided with a water extraction chamber filled with an intermediate pressure fluid and a water extraction stage for sending a fluid of the intermediate pressure to the water extraction chamber, the water extraction chamber and the discharge chamber are provided after the water extraction stage. A fitting surface is provided on the inner and outer peripheral surfaces of the outer casing and the stage, and sealing is performed by an O-ring interposed between the outer casing and the stage, and a radial movement of the inner casing is achieved by the fitting surface of the outer casing and the inner casing. A barrel casing type turbine pump, characterized in that