CN101215977A - Steam turbine nozzle set and its machining process - Google Patents

Abstract

The invention discloses a steam turbine nozzle block and a manufacturing process thereof. The nozzle block comprises an external ring support body, an internal ring support body and a blade row arranged between the external ring support body and the internal ring support body. The blade row is annular, and is provided with a plurality of guide blades arranged in the circumferential direction. The guide blades, the internal ring and the external ring are in a split structure. The guide blades are assembled to form the blade row. The blade row is arranged on the internal ring support body and the external ring support body to constitute the nozzle block. The nozzle block is assembled on a nozzle box. The guide blades are provided with integral tip shrouds on the upper parts and the lower parts. The upper semi-ring and the lower semi-ring of the blade row are formed by combining a plurality of fan-shaped arc segments. The coupling sections of adjacent arc segments adopt a lapping structure. The processing steps are as follows: the guide blades are processed one by one; all of the guide blades are combined into the blade row; the blade row is arranged between the external ring support body and the internal ring support body. Lug bosses are processed and arranged on the external ring support body in the circumferential direction. The structure of the nozzle block is rational, and is applicable for high-power assemblies. The components are processed and assembled easily, and are highly precise with small heat stress. The entirety of the nozzle block is excellent.

Description

Nozzle of steam turbine group and processing technology thereof

Technical field

The present invention relates to steam turbine, relate in particular to the nozzle sets and the processing technology thereof of steam turbine.

Background technique

The effect of nozzle is that heat energy with steam changes kinetic energy in the steam turbine, and makes steam flow enter governing stage by certain direction.Nozzle is fixed in cylinder or the nozzle box, is the main static part that steam turbine is realized transformation of energy.Nozzle of steam turbine is the stream passageway with certain molded lines, and steam flows through in nozzle, the expansion step-down, and steam flow quickens, and change the heat energy of steam into kinetic energy, and the guiding steam flow flows through the movable vane steam passage by certain direction.

Referring to Fig. 1, the conventional nozzle group is directly to mill guidance blade nozzle group from nozzle ring.This nozzle of steam turbine group by encircle 1 in the nozzle ', root piece 2 ', nozzle outer shroud 3 ' form, guide vane directly in the nozzle ring go up and mill out with milling cutter, with interior ring be overall structure, the remaining part of interior ring is the total root of all guide vanes.Guide vane mills into inside and outside arc-shaped curved surface by molded lines, and outer, the arc curved surface of adjacent two guide vanes match, and form the stream passageway of nozzle.

Nozzle sets has characteristics such as operating temperature height, front and back pressure reduction be big.In order to guarantee the intensity of nozzle sets, also, make the nozzle sets guide vane have good aeroperformance simultaneously, so the stream passageway of nozzle is reasonable in design in order to guarantee large steam turbine flow area and the needs that satisfy frequency modulation.General high power turbine unit nozzle sets blade number of elements is more, and the number of elements of guide vane is many more under the fixed structure, and its throat dimension is just more little, and the fitting surface of adjacent guide vane sheet is an abnormal curved surface, and difficulty of processing is just big more, and precision is difficult to guarantee.

In addition and since guide vane directly in the nozzle ring go up and mill out with milling cutter, should axial feed, integral shroud is not with in radially feed, thereby guide vane again, can not form shroud structure, need add in addition between the position that root piece is fixed on guide vane, to form the steam flow passage.And the complex process of assembling root piece, the degree of finish of assembling back steam flow passage is not high, and the combination property of nozzle sets is not good enough.

Have, nozzle sets is to constitute whole circle by several segmental arcs again, and leaf grating and nozzle box are welded as a whole, and the leaf grating thermal expansion is not as the assembling type free expanding, and thermal stress is big.In addition, integral solder formula nozzle sets axial dimension is longer relatively, will increase total axial dimension of steam turbine.

Therefore the nozzle sets structure of above-mentioned steam turbine and processing technology thereof need to improve.

Summary of the invention

One of purpose of the present invention provides a kind of nozzle of steam turbine group, and the structure of this nozzle sets is more reasonable, is fit to powerful unit; Processing, the assembling difficulty of each component are low, the precision height, and thermal stress is little, and the overall performance of nozzle sets is more excellent.

Two of purpose of the present invention provides a kind of processing technology that is fit to above-mentioned nozzle of steam turbine group.

Concrete technical solution of the present invention is:

A kind of nozzle of steam turbine group comprises outer shroud support, interior ring support and between the leaf grating between them, this leaf grating has the guide vane of a plurality of circumferential arrangement in the form of a ring; Described guide vane and interior ring and outer shroud are the branch body structures, and all guide vane assemblings constitute leaf grating; Leaf grating is assemblied on the inner and outer rings support, constitutes nozzle sets.

Described nozzle sets is assemblied in the nozzle box, is fabricated construction.

Described guide vane carries integral shroud up and down, and the integral shroud of all guide vanes constitutes shroud structure.

Described nozzle sets is upper and lower half hitch structure, and upper and lower half point is not made of several fan-shaped segmental arcs, and bridging arrangement is adopted in the connecting part of adjacent segmental arc.

Expansion gap is left in the connecting part of described adjacent segmental arc.

Described segmental arc is provided with locating stud.

Described nozzle sets upper and lower half is provided with seal bond with the connecting part of nozzle box.

The processing technology of above-mentioned nozzle of steam turbine group comprises step:

1. distinguish a work sheet guide vane;

2. all guide vanes are combined into leaf grating;

3. leaf grating is loaded between outer shroud supporting mass and the interior ring bearing body, processes circumferential installation base on the ring bearing body outside.

2. described step further comprises step:

Guide vane is combined into several segmental arcs respectively, the integral shroud of the guide vane in each segmental arc part and leaf root part are welded respectively, make each segmental arc become integral body.

3. described step further comprises step:

A. will belong to the segmental arc of semi-ring and following semi-ring on the leaf grating and be loaded on corresponding position between outer shroud supporting mass and the interior ring bearing body one by one, adjust the relative position of each segmental arc;

B. with the last integral shroud part and the welding of outer shroud supporting mass of each segmental arc, inferior lobe crown moieties and the welding of interior ring bearing body constitute the nozzle sets blank;

C. with lathe on the nozzle sets blank, process circumferential installation base on the ring bearing body outside, this boss matches with circumferential installation groove in the nozzle box.

Useful technique effect of the present invention is:

1.. the guide vane single-piece work, the machining accuracy height, the blade roughness reaches 1.6, and steam passage is bright and clean, and aeroperformance is more superior; And be convenient to produce in batches, with short production cycle, low cost of manufacture.

2.. nozzle guide vane sheet self-crown, blade blade and integral shroud are one, by the machining moulding, have saved root piece, make guide vane manufacturing and leaf grating precision height in groups, help guaranteeing the thermal efficiency of nozzle of steam turbine group.

3.. when this assembling type nozzle of steam turbine group is heated, the circumferentially free expansion of nozzle sets segmental arc, the heat expansion resistance is little, and thermal stress and amount of deformation are little, the operational reliability height.

Description of drawings

Fig. 1 is the structural representation of existing nozzle of steam turbine group.

Fig. 2-1,2-2,2-3 are the structural representations of nozzle sets of the present invention, wherein:

Fig. 2-the 1st, nozzle sets steam output side view;

Fig. 2-the 2nd, the A-A view of Fig. 2-1;

Fig. 2-the 3rd, the long splice composition of nozzle sets leaf grating and nozzle sets inner and outer rings.

Fig. 3-1,3-2,3-3 are the structural drawing of guide vane, wherein:

Fig. 3-the 1st, the guide vane plan view;

Fig. 3-the 2nd, the side view of Fig. 3-1;

Fig. 3-the 3rd, the A-A view of Fig. 3-1.

Fig. 4-1,4-2,4-3 are the cascade structure schematic representation, wherein:

Fig. 4-the 1st, leaf grating steam output side view;

Fig. 4-the 2nd, the B-B view of Fig. 4-1;

Fig. 4-the 3rd, leaf grating dress weldering unfolded drawing.

Embodiment

Referring to Fig. 2-1, Fig. 2-2, Fig. 2-3: this nozzle of steam turbine group comprises outer shroud support 1, interior ring support 2 and between the leaf grating between them 3, and this leaf grating 3 is constituted by the guide vane 4 of a plurality of circumferential arrangement in the form of a ring.

One of main feature of the present invention is with guide vane 4 and interior ring support 2 design mix body structures, earlier with after guide vane 4 single the processing, refills and is made into leaf grating 3, leaf grating 3 is contained between outer shroud support 1 and the interior ring support 2 then.Two of main feature of the present invention is to process the hoop assembly structure after leaf grating 3 is loaded on outer shroud support 1 and interior ring support 2, and nozzle sets is assemblied in the nozzle box 8.

Referring to Fig. 3-1, Fig. 3-2, Fig. 3-3: guide vane 4 has blade 401, integral shroud 402, blade root 403.Blade 401 has outer arc surface 404, interior arc surface 405.After all guide vanes 4 were assembled into leaf grating 3, the space that the outer arc surface 404 of adjacent two guide vanes 4, interior arc surface 405, integral shroud 402, blade root 403 surround just constituted the nozzle steam passage, and integral shroud 402, the blade root 403 of all guide vanes 4 just constitute the Shround-band type structure.

The same with other static part of steam turbine, the outer shroud support 1 of nozzle sets, interior ring support 2 and leaf grating 3 also are upper and lower minute half hitch structures, wherein, the upper and lower semi-ring of leaf grating 3 is made of several fan-shaped segmental arcs respectively, shown in Fig. 4-1, Fig. 4-2, semi-ring, following semi-ring are respectively constituted by two fan-shaped segmental arcs on the leaf grating, and each fan-shaped segmental arc all has a plurality of guide vanes 4, and the guide vane 4 at segmental arc two ends is only processed cambered surface of steam passage.Process the hoop assembly structure after leaf grating 3 is loaded on outer shroud support 1 and interior ring support 2, nozzle sets is assemblied in the nozzle box 8.One of them end of nozzle sets segmental arc is processed with pin-and-hole, and the pin-and-hole centering in this pin-and-hole nozzle box is used for installing and locating pin 5.Bridging arrangement is adopted in the connecting part of adjacent two segmental arcs, has overlap joint step seam 6, shown in Fig. 4-3.Expansion gap is left in the connecting part of each segmental arc of nozzle sets.Leak vapour for stoping, this place also is provided with seal bond 7, and seal bond is loaded in the groove that is located on the nozzle sets, is loaded in the nozzle box with nozzle sets.

Processing, the assembly technology of this nozzle sets are as follows:

Process single guide vane earlier, the guide vane that will belong to same leaf grating segmental arc places on the template, to determine the relative position of each guide vane, again with the continuous sealing weld of welding groove at the integral shroud position and the blade root position of adjacent guide vane sheet, make this segmental arc become integral body, the postwelding stress relief annealing, the steam passage reconditioning is bright and clean.

Each leaf grating segmental arc is placed between the inner and outer rings support, determine the relative position of each segmental arc and inner and outer rings support, with the integral shroud position and the welding of outer shroud supporting mass of each segmental arc, blade root position and the welding of interior ring bearing body constitute the nozzle sets blank.

With lathe on the nozzle sets blank, on its outer circumferential face, process circumferential installation base, this boss matches with circumferential installation groove in the nozzle box.

When general assembly, with the upper and lower half point of the nozzle sets nozzle box upper and lower half of not packing into.

Claims (10)

1. nozzle of steam turbine group comprises outer shroud support, interior ring support and between the leaf grating between them, this leaf grating has the guide vane of a plurality of circumferential arrangement in the form of a ring; It is characterized in that described guide vane and interior ring and outer shroud are the branch body structures, all guide vane assemblings constitute leaf grating; Leaf grating is assemblied on the inner and outer rings support, constitutes nozzle sets.

2. nozzle of steam turbine group according to claim 1 is characterized in that described nozzle sets is assemblied in the nozzle box.

3. nozzle of steam turbine group according to claim 1 is characterized in that described guide vane carries integral shroud up and down, and the integral shroud of all guide vanes constitutes shroud structure.

4. nozzle of steam turbine group according to claim 1 is characterized in that, described nozzle sets is upper and lower half hitch structure, and upper and lower half point is not made of several fan-shaped segmental arcs, and bridging arrangement is adopted in the connecting part of adjacent segmental arc.

5. nozzle of steam turbine group according to claim 4 is characterized in that expansion gap is left in the connecting part of described adjacent segmental arc.

6. nozzle of steam turbine group according to claim 4 is characterized in that described segmental arc is provided with locating stud.

7. nozzle of steam turbine group according to claim 4 is characterized in that, described nozzle sets upper and lower half is provided with seal bond with the connecting part of nozzle box.

8. the processing technology of a nozzle of steam turbine group comprises step:

1. distinguish a work sheet guide vane;

2. all guide vanes are combined into leaf grating;

3. leaf grating is loaded between outer shroud supporting mass and the interior ring bearing body, processes circumferential installation base on the ring bearing body outside.

9. the processing technology of nozzle of steam turbine group according to claim 8 is characterized in that, 2. described step further comprises:

Guide vane is combined into several segmental arcs respectively, the integral shroud of the guide vane in each segmental arc part and leaf root part are welded respectively, make each segmental arc become integral body.

10. the processing technology of nozzle of steam turbine group according to claim 8 is characterized in that, 3. described step further comprises step:

A. will belong to that the segmental arc of semi-ring and following semi-ring is loaded between outer shroud supporting mass and the interior ring bearing body one by one on the leaf grating, adjust the relative position of each segmental arc;

B. with the last integral shroud part and the welding of outer shroud supporting mass of each segmental arc, inferior lobe crown moieties and the welding of interior ring bearing body constitute the nozzle sets blank;

C. with lathe on the nozzle sets blank, process circumferential installation base on the ring bearing body outside, this boss matches with circumferential installation groove in the nozzle box.

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