JPS6048603B2 - Turbine nozzle - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a nozzle for a total flow turbine that injects a two-phase flow of saturated hot water and dry steam onto turbine rotor blades.

In a total flow turbine that operates with a two-phase flow containing saturated hot water and slightly dry steam (saturated steam), it is said that the smaller the size of water droplets contained in the steam, the better the efficiency.

For example, in order to obtain an efficiency of 70%, it is necessary to form water droplets of 1 micron or less, and the atomization of these water droplets is carried out using a two-phase nozzle. Conventionally, as shown in Fig. 1, water droplets are miniaturized using a simple Laval nozzle that has a throat part 2 that is extremely sandwiched in the middle of a horizontal part 1, and a tapered part 3 that gradually widens at its tip. is going on.

However, this simple Laval nozzle has the disadvantage that it has little effect on making water droplets fine, so a slit 4 is provided in the throat part 2 of the Laval nozzle as shown in Fig. A method is being considered in which saturated steam is introduced from the center of the tube. In the method shown in Fig. 2, the water droplets can be made very small, but on the other hand, a special separator 5 is required to separate the two-phase flow of saturated water and saturated steam, which increases the size of the device and makes it difficult to separate the water droplets. It has the disadvantage of requiring extra steps. The present invention eliminates the above drawbacks, separates saturated moisture and saturated steam without using a special separator, and mixes them at the throat of the nozzle, thereby achieving supersonic speed containing small water droplets. The purpose of the present invention is to provide a nozzle for a total flow turbine.

That is, the present invention provides a nozzle for a total flow turbine that operates with a two-phase flow containing saturated hot water and dry steam, in which a bent flow path duct is connected to the throat portion of the nozzle, and the bent portion is provided in the duct. This turbine nozzle is characterized in that a partition plate is inserted from the nozzle to the throat of the nozzle at the downstream opening.

An embodiment of a turbine nozzle according to the present invention will be described below with reference to FIGS. 3 to 6.

In FIG. 3, at the tip of the tapered nozzle 10, there is a Ξ-angular cone 11 that injects a mixed flow containing small water droplets at a supersonic speed, facing the turbine rotor blade 8, through a connecting duct 12. A flow path duct 14 bent in a substantially S-shape is connected to the rear end throat portion 13 of the nozzle 10 . As shown in enlarged form in FIGS. 4 and 5, this flow path duct 14 has a portion 15 bent from the end connected to the throat portion 10 of the nozzle 10 and a portion 16 bent from the bottom to the top. A first partition plate 17 and a second partition plate 18 having curvatures matching the shapes of the respective bent portions 15 and 16 are inserted and fixed to the inner wall surfaces of the bent portions 15 and 16, respectively. 4 is an enlarged vertical cross-sectional view of the circular portion A in FIG. 3, FIG. 5 is a cross-sectional view of FIG. 4 viewed from below, and FIG. It is a conceptual diagram for diagrammatically explaining the state of a two-phase flow. In the above-mentioned turbine nozzle, when a two-phase flow of saturated water and saturated steam is introduced from the inlet 19 of the flow path duct 14, the two-phase flow is divided into water and steam components by centrifugal force at the bent portions 15 and 16. The separated water is guided as hot water to the throat portion 13 of the nozzle 10 through saturated water passages 20, 21 formed between the partition plates 17, 18 and the inner surfaces of the duct. At this time, almost only steam flows through the flow path in the center of the duct 14. (See FIG. 6) In the figure, ♀ indicates droplets, hatched areas indicate saturated water, arrow A indicates saturated water flow, and arrow B indicates saturated steam flow. The mechanism by which droplets become atomized is that there is a large temperature difference between water and steam, and the most significant one is the boiling effect. Therefore, it is most effective to inject hot water into the steam whose temperature has decreased by expanding through the throat portion 13 of the nozzle 10. As explained above, according to the present invention, in a total flow turbine that operates with a two-phase flow containing saturated hot water and a slight amount of dry steam, a bent duct is connected to the throat of the nozzle that injects water to the turbine rotor blades. The purpose of this method is to insert a partition plate into the bent part of the duct to atomize the saturated water in the two-phase flow and inject a supersonic flow containing small droplets.

Therefore, a supersonic flow can be easily created with high efficiency without requiring a special separator for separating two-phase flows as in the past.

Note that when a two-phase flow is ejected from a conventional simple Laval nozzle, the droplet diameter is about 2 microns at 25 atmospheres, and 4 microns at river pressure.

In order to obtain high efficiency in a total flow turbine, it is necessary to reduce the diameter of the droplets to 1 micron or less, which can be easily achieved in the present invention. Further, in the present invention, it is possible to create a supersonic flow containing small droplets even in a low-pressure two-phase flow. The present invention is not limited to the above-mentioned embodiment, but the bent portion 16 and partition plate 17 in FIG. You can also do that. Further, the number of bent parts may be single or plural, but the more the number, the more effective it is, and the shape of the partition plate does not have to match the shape of the bent part, and is not limited as long as it forms a passage for saturated water flow. Brief Description of the Drawings Figures 1 and 2 are vertical sectional views showing conventional turbine nozzles, and Figures 3 to 6 are longitudinal sectional views showing conventional turbine nozzles.
The figures up to the figure are diagrams showing one embodiment of the turbine nozzle according to the present invention, FIG. 3 is a perspective view showing the overall configuration of the turbine nozzle, and FIG. 4 is an enlarged view of the circular part A in FIG. 3. 5 is a cross-sectional view of FIG. 4, and FIG. 6 is a conceptual diagram diagrammatically showing the state of the two-phase flow flowing in the duct in FIG. 4.

1... Horizontal part, 2... Throat part, 3... Taper part, 4... Slit, 5... Separator, 8... Moving blade, 10... Nozzle, 11...・Corn, 12...
Connection duct, 13... Throat part, 14... Channel groove, 15, 16... Bent part, 17, 18... Partition plate, 19... Inlet, 20, 21... Saturated water aisle.

Claims (1)

[Claims] 1. In a total flow turbine nozzle that operates with a two-phase flow containing saturated hot water and dry steam, a bent flow path duct is connected to the throat portion of the nozzle, and a downstream outlet from the bent portion is connected to the throat portion of the nozzle. A turbine nozzle characterized by having a partition plate inserted all the way to the throat of the nozzle.