CN1276849A - Exhaust duct for steam turbine - Google Patents

Abstract

The present invention relates to an exhaust duct for a steam turbine, wherein said duct comprises a removable body having in its lower part one pair or two pairs of devices for generating opposed turbulence. These devices for generating opposed turbulence are mounted symmetrically relative to the duct longitudinal axis, the distance which represents from 1-1.2 times of the diameter of the working vane in the last stage and are made in the shape of a grid comprising intersecting plates. Each plate has a length which represents from 45 to 60 % of the length of the working vane in the last stage. The plates define at the cross section a plurality of rectangular cells having their opposite edges separated by a distance which represents from 30 to 40 % of the length of the working vane in the last stage.

Description

steam turbine exhaust

The invention belongs to power machine manufacturing and can be applied to the design and improvement of steam turbine exhaust pipes.

Known steam turbine exhaust pipes consist of a pipe body with a horizontal split which divides the pipe body into two parts: an upper part and a lower part, in which the last working impeller of the steam turbine is installed, possibly also Mounted axially radially radiating horn with inner and outer rings (cf. e.g. a.c.SU 1605003, КЛ.F 01D 25/30, 07.11.90 and RU2040697, КЛ.F 01D 25/30, 27.07.95 ).

The common disadvantage of these exhaust pipes is that when the steam flow is discharged to the underground condenser, it turns 180 degrees at the upper part of the exhaust pipe, and is rolled into two powerful vortex bundles. These vortex bundles block a relatively large part of the passage area below the exhaust pipe body, resulting in a severe inhomogeneity of the velocity field at the condenser inlet. As a result, the dynamic pressures acting on the structural components of the turbine and the condenser connecting pipes increase dramatically. Also, non-uniformity in the airflow output reduces the rate of heat removal from steam to cooling water.

There is known a steam turbine exhaust pipe described in a.c.SU 169947, КЛ.F 01D 25/30, 17.03.65, wherein the pipe body is made with a horizontal detachable joint, with a split edge system. The main disadvantage of such an exhaust pipe is the complex system of curved edges, which creates secondary airflow intensities and vortex bundles in each curved groove, with the result that the losses increase sharply, even at low dimensionless velocity M at the pipe inlet. will happen. Furthermore, although the exhaust pipe is slightly stiffer, the vibration of the turbine bearings housed in the exhaust pipe body cannot be significantly reduced using the rib system due to the poor aerodynamics of the air flow.

The invention solves the problem of increasing the reliability and economy of steam turbine exhaust pipes in two embodiments while reducing energy consumption and at the same time reducing vibrations of the overall structure of the steam turbine exhaust pipe. Solving this task depends on reducing the inhomogeneity of the velocity field at the exit section of the exhaust pipe, which is also the technical effect achieved by the present invention.

In the first embodiment of the present invention, this technical effect is achieved by means of the following measures: the exhaust pipe body of the steam turbine is made of rigid parts, consisting of two parts (upper and lower) ), two anti-vortex devices are installed on the lower part of the pipe body, which are symmetrically distributed relative to the longitudinal axis of the exhaust pipe, and the distance is 1-1.2 times the diameter of the last stage of the working impeller. Each anti-vortex device is composed of overlapping The grid composed of flat plates, the length of each plate is 45-60% of the length of the last-stage working blade, and the overlapped flat plates form a grid with a rectangular cross-section, and the distance between the opposite sides is 30-60% of the length of the last-stage working blade. 40%. The anti-vortex device is rigidly fixed on the side wall of the lower part of the detachable connecting pipe body, the upper end of the overlapping plate coincides with the interface horizontal plane, and the section of the rectangular cell is parallel to the interface plane.

In the second embodiment of the present invention, it relates to a turbine exhaust pipe with a radial horn-shaped fan cylinder. The above-mentioned technical effects are obtained because the steam turbine exhaust pipe body is made of rigid elements, including strips The two detachable parts (upper and lower) of the horizontal joint surface are equipped with two pairs of anti-vortex devices on the lower part of the pipe body, and each pair of anti-vortex devices is symmetrically distributed relative to the longitudinal axis of the pipe body. Any anti-vortex device is composed of overlapping plates to form a grid shape, and the length of each plate is 45-60% of the length of the last-stage working blade. The overlapping plates form a rectangular hole, and the distance between the opposite sides is the last-stage working blade. 30-40% of the length, and any one of a pair of anti-vortex devices is rigidly fixed on the side wall of the lower part of the detachable pipe body and the peripheral tube of the trumpet-shaped air duct. Any one of the other pair of anti-vortex devices is fixed on the side wall of the lower part of the detachable connecting pipe body and the inner circumference of the horn-shaped air cylinder. parallel.

Essence of the present invention is explained with accompanying drawing, and accompanying drawing 1 shows schematically the longitudinal section of the lower portion of the steam turbine exhaust pipe of the first embodiment of the present invention, and Fig. 2 schematically depicts the overall view of the exhaust pipe (first embodiment ), on Fig. 3, show the longitudinal section of the second embodiment of the steam turbine exhaust pipe of the invention, and Fig. 4 schematically depicts the overall view of the turbine exhaust pipe (the second embodiment).

The logos used on Figures 1, 2, 3, and 4 are as follows:

1-pipe body (the rigid fixing parts are not shown in Fig. 1 and Fig. 3)

2 - the upper part of the tube body 1

3 - the lower part of the tube body 1

4-Horizontal joint surface of upper part 2 and lower part 3 of pipe body 1

5-rectangular hole

6 - The side wall of the lower part 3 of the tube body 1

7-Grid-shaped anti-vortex device (first embodiment) composed of overlapping plates 8

9,10-Two pairs of anti-vortex devices, any one of which is made into a grid by overlapping flat plates 11 (the second embodiment of the invention)

12-Peripheral cylinder of horn-shaped air cylinder (the second embodiment of the invention)

13-The inner circumference of the trumpet-shaped air duct (the second embodiment of the invention)

In the first embodiment of the invention, on the detachable lower part 3 of the pipe body 1, two anti-vortex devices 7 are installed symmetrically to the longitudinal axis O of the pipe body, the distance between the two being the last stage 1-1.2 times the diameter of the working impeller. Any one among the anti-vortex devices 7 forms a grid shape with overlapping flat plates 8, and the length of each flat plate is 45-60% of the length of the last stage of working blades. The distance across sides is 30-40% of the length of the last stage of working vane. Each anti-vortex device 7 is rigidly fixed on the side wall 6 of the detachable lower part 3 of the pipe body 1, the upper part of the overlapping plate 8 coincides with the interface level 4, and the cross section of the rectangular hole 5 is parallel to the interface.

In a second embodiment of the invention, on the detachable lower part 3 of the tubular body 1, two pairs of anti-vortex devices 9 and 10 are mounted symmetrically to the longitudinal axis O of the tubular body, any one of which uses an overlapping plate 11 Form a grid shape, the length of each flat plate is 45-60% of the length of the last-stage working blade, the flat plate forms a rectangular hole 5 in section, and the distance between opposite sides is 30-40% of the length of the last-stage working blade . Any one of the anti-vortex devices 9 is rigidly fixed on the side walls and 6 of the detachable bottom 3 of the pipe body 1 and the peripheral tube 12 of the trumpet-shaped air duct, and any one of the anti-vortex devices 10 They are all fixed on the side wall 6 of the detachable part of the lower part of the pipe body 1 and the inner peripheral cylinder 13 of the trumpet-shaped air cylinder, and the upper part of the overlapping plate 11 is required to coincide with the interface level 4 of the upper part 2 and the lower part 3 of the pipe body 1. , the cross section of the rectangular hole 5 is parallel to the interface.

According to the proposed embodiment, the steam turbine exhaust pipe works in this way. The steam from the last working turbine enters the pipe body 1 of the exhaust pipe, and in its upper part 2 the steam flow turns 180 degrees, resulting in the formation of two powerful vortex beams, which grow rapidly and reach the outlet section of the pipe body 1, Occupying most of its area, the result not only greatly increases the fluid resistance of the exhaust pipe, especially under the condition that the dimensionless velocity value M1 at the entrance of the pipe is considerable, but also the instability of the vortex will cause the exhaust pipe body 1 and The turbine components connected to it vibrate strongly at low frequencies. However, the application of the anti-vortex devices 7 and 9, 10 proposed by the present invention in the exhaust pipe breaks up the steam vortices where their intensity increases sharply. The anti-vortex device is realized by the plate 8 and the plate 11, and their longitudinal arrangement allows the steam flow to flow unimpeded along the entire width of the pipe body 1, thereby ensuring that the steam flow fills the entire air outlet surface relatively completely. In addition, the anti-vortex device 7 or 9, two grid tube groups composed of overlapping flat plates 8 or 11 are installed on the lower part 3 of the tube body 1, directly at the horizontal interface of the tube body, so that the rigidity of the structure Enhanced, its vibration is greatly reduced. The evaluation of the dimensions of the plates 8 or 11 used and the grid composed of them proceeds from the following considerations. The distance between adjacent plates 8 and 11 directly affects the efficiency of breaking up the vortex beam. The smaller the distance, the better the breaking of the vortex beam, but at the same time the greater the fluid resistance. As the reference size, choose the most suitable size of the flat plates 8 and 11 and the grid formed by them relative to this reference size, get the diameter of the working turbine and the height of the last stage blade. The connection of the plates 8 and 11 to each other and to the tubular body 1 of the tube is expediently made by means of load-bearing elements, for example in the form of rods of circular cross-section. Rods of circular cross-section are insensitive to changes in the angle of airflow inflow. Considering the complexity and spatial distribution of the steam flowing in the pipe body 1, the connecting parts are very large.

Invention applicable to the construction of new and improved existing and operating steam turbine exhaust pipes which, in the presence of the sum of the main features enumerated above, ensure the breakdown of vortices generated in the upper part of the exhaust pipe body The beam can make the velocity field of the outlet section of the exhaust pipe uniform, and reduce the fluid resistance and vibration of the exhaust pipe, so that a reliable and economical exhaust pipe can be manufactured.

Claims (2)

1. the outlet pipe of a turbo machine comprises the body of being with rigid element, band interface horizontal plane disconnect on, following two-part, it is characterized in that the lower part that disconnects of body disposes two anti-swirling devices of the longitudinal axis symmetrical distribution of relative pipe, and their distance is 1-1.2 times of afterbody work turbine diameter, among the anti-swirling device any one all uses overlapping flat panel production to become grid-like, the length of every flat board is the 45-60% of afterbody running wheel length, overlapping dull and stereotyped formation section is the hole lattice of rectangle, the distance of hole lattice opposite side is the 30-40% of afterbody working blade length, and each anti-swirling device is rigidly fixed on the sidewall of the lower part that disconnects of body, overlapping dull and stereotyped top overlaps with the interface horizontal plane, and the transverse section of rectangular opening lattice is parallel with interface.

2. the outlet pipe of a steam turbine comprises the body of being with rigid element, band interface horizontal plane disconnect on, following two-part and being installed in the having in the body, the diameter of axle of external bustle pipe is to tubaeform air duct, the lower part that disconnects that it is characterized in that body disposes two pairs of anti-swirling devices, and the longitudinal axis of every pair of relative pipe of anti-swirling device is symmetrically distributed, each anti-swirling device is made grid-like with overlapping flat board, the length of every flat board is the 45-60% of afterbody working blade length, overlapping dull and stereotyped formation section is the hole lattice of rectangle, the distance of hole lattice opposite side is the 30-40% of afterbody working blade length, and the every pair of anti-swirling device so be rigidly fixed to the body lower part sidewall and and tubaeform air duct in enclose on the tube, overlapping dull and stereotyped top and interface horizontal plane are coincide, and the transverse section of rectangular opening lattice is parallel with interface.

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