Front-mounted steam turbine suitable for high exhaust steam pressure and steam turbine system

Abstract

The invention discloses a front-mounted steam turbine suitable for high exhaust steam pressure and a steam turbine system.The inner cylinder of the front-mounted steam turbine comprises a first inner cylinder body and a second inner cylinder body which are formed by a first interface passing through the axis, and the outer cylinder of the front-mounted steam turbine comprises a first outer cylinder body and a second outer cylinder body which are formed by a second interface perpendicular to the axis; the two sides of the cylinder walls of the first inner cylinder body and the second inner cylinder body are respectively sleeved and fixed through circular rings; annular skirt parts are respectively arranged on the inner wall surfaces of the first outer cylinder body and the second outer cylinder body and are respectively matched with the peripheral surface of the circular ring; the two annular skirt parts, the outer wall face of the inner cylinder and the inner wall face of the outer cylinder form a low-pressure cavity, and a pressure balance hole penetrating to the low-pressure cavity is formed in the cylinder wall of the outer cylinder and used for being communicated with a low-pressure area. On the basis of overall structure optimization, the bearing capacity of the outer cylinder can be effectively improved, a pressure isolation mechanism is established on the basis of the low-pressure cavity, the action range of high exhaust steam pressure is greatly reduced, and reliable technical guarantee is provided for improving the exhaust steam pressure of a unit.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of coal-fired power generation technology, in particular to a front-mounted steam turbine suitable for high exhaust steam pressure and a steam turbine system. BACKGROUND

[0002] The front-mounted steam turbine is usually connected in series with other steam turbines such as a main steam turbine, and in the working process, the front-mounted steam turbine uses steam with higher parameters to convert energy and do work, recovers the initial energy of high-pressure steam, and then delivers exhaust steam with high pressure and temperature to the subsequent steam turbine for continued expansion and work, so that the overall power generation capacity of the power plant can be effectively improved through this series cooperation mode.

[0003] Among them, the inlet steam pressure and the exhaust steam pressure of the front-mounted steam turbine are at a high level, and the structural design needs to meet the trend of compactness to ensure that the cylinder has good sealing performance and sufficient strength. A typical front-mounted steam turbine includes an outer cylinder and an inner cylinder, which realizes reasonable sharing of pressure gradient, however, the high exhaust steam pressure is mainly borne by the outer cylinder.

[0004] In order to ensure that the outer cylinder of the front-mounted steam turbine can stably bear the high steam pressure, the cylinder structure design and material selection can be systematically optimized and upgraded, however, the exhaust steam pressure of the front-mounted steam turbine needs to be controlled within a safe threshold range, such as but not limited to 10 MPa, to ensure safe and stable operation, and it is difficult to meet the evolution of units with higher exhaust steam pressure.

[0005] For units with higher exhaust steam pressure, the conventional solution is to increase the cylinder wall thickness, select high-strength materials, and increase the size of the bolts to enhance the cylinder strength and sealing performance. However, these measures will increase the cylinder thermal stress during the start and stop of the steam turbine, and limited by the material performance and thermal stress constraints, the exhaust steam pressure of the unit is still difficult to effectively break through.

[0006] Therefore, it is urgent to optimize the operation structure of the front-mounted steam turbine to overcome the above-mentioned defects. SUMMARY

[0007] To solve the above technical problems, the present application provides a front-mounted steam turbine suitable for high exhaust steam pressure and a steam turbine system, which can effectively improve the carrying capacity of the outer cylinder through overall structural optimization, providing reliable technical support for increasing the exhaust steam pressure of the unit.

[0008] The application provides a front-mounted steam turbine suitable for ultra-high exhaust pressure, which comprises an outer cylinder and an inner cylinder arranged in a nested mode, wherein the outer cylinder and the inner cylinder are both split structures, the inner cylinder comprises a first inner cylinder body and a second inner cylinder body formed by a first boundary surface passing through an axis, and the first inner cylinder body and the second inner cylinder body are fixedly connected through a first connecting bolt embedded in the cylinder body; the outer cylinder comprises a first outer cylinder body and a second outer cylinder body formed by a second boundary surface perpendicular to the axis, and the opening ends of the first outer cylinder body and the second outer cylinder body both have annular flanges and are fixedly connected through a second connecting bolt penetrating the two annular flanges; the cylinder walls of the first inner cylinder body and the second inner cylinder body both have reduced diameter sections on both sides and are fixed through interference-fitted circular ring sleeves; the inner wall surfaces of the first outer cylinder body and the second outer cylinder body are respectively provided with annular flared skirts, both of which extend towards the inner cylinder and are respectively matched with the outer peripheral surfaces of the corresponding circular rings; the annular flared skirts and the outer wall surface of the inner cylinder and the inner wall surface of the outer cylinder form a low-pressure chamber, and the cylinder wall of the outer cylinder is provided with a pressure balance hole penetrating into the low-pressure chamber, which is used for connecting the low-pressure area.

[0009] Optionally, the pressure balance hole is arranged in the cylinder wall of the first outer cylinder body.

[0010] Optionally, the annular flared skirts and the outer peripheral surfaces of the corresponding circular rings are matched with zero clearance through a sealing ring.

[0011] Optionally, the first inner cylinder body and the second inner cylinder body enclose a steam inlet chamber, and the steam inlet chamber has two steam inlets respectively communicating with the steam inlet chamber on the diametrically opposite sides;

[0012] The outer wall surface of the steam inlet chamber on one side of the center line connecting the two steam inlets and the outer wall surface of the steam inlet chamber on the other side of the center line connecting the two steam inlets both change in a gradually decreasing trend from one steam inlet to the other steam inlet in the radial direction, and accordingly, the wall thickness of the cylinder wall of the inner cylinder changes in a gradually increasing trend; the outer wall surface on one side of the center line connecting the two steam inlets is rotationally symmetrical to the outer wall surface on the other side of the center line connecting the two steam inlets with respect to the center of the rotor.

[0013] The first boundary surface is located in the radially small-size region of the outer wall surface on both sides, and the first connecting bolt is embedded in the two-side cylinder walls with relatively thick wall thickness corresponding to the radially small-size region.

[0014] Optionally, the radially small-size end of the outer wall surface has a flow guide arc surface, and the radially large-size end of the outer wall surface has a flow guide round corner.

[0015] Optionally, the inner cylinder comprises a support positioning protrusion protruding radially outward from the outer wall of the inner cylinder; the outer cylinder comprises a support limiting protrusion protruding radially inward from the inner wall of the first outer cylinder body; the inner cylinder and the outer cylinder are fixedly connected through the matched support positioning protrusion and the support limiting protrusion.

[0016] Optionally, the matched support positioning protrusion and the support limiting protrusion are arranged in multiple groups and are arranged uniformly in the circumferential direction.

[0017] Optionally, the support limiting protrusion has a groove, the groove bottom wall is an axial limiting surface matched with the support positioning protrusion, and the two circumferentially opposite groove side walls are circumferential limiting surfaces matched with the support positioning protrusion.

[0018] Optionally, the outer cylinder further comprises an auxiliary limiting protrusion protruding radially inward from the inner wall of the first outer cylinder body and located close to the opening side of the first outer cylinder body in the axial direction, and the axial spacing between the auxiliary limiting protrusion and the support limiting protrusion is provided with a limiting baffle to axially limit the support positioning protrusion; the auxiliary limiting protrusion has an axial through insertion slot, so that the support positioning protrusion passes through the insertion slot and matches with the support limiting protrusion, the insertion slot is provided with a locking block, and the locking block and the limiting baffle are fixed by a locking bolt.

[0019] Optionally, the surface of the limiting baffle towards the insertion slot has a stop recess, the locking block has a stop protrusion, and the stop protrusion is inserted into the stop recess of the limiting baffle.

[0020] Optionally, the circumferential spacing between the support positioning protrusion and the two axial limiting surfaces has an insertion gasket to circumferentially limit the support positioning protrusion.

[0021] Optionally, the front-mounted steam turbine is a front-mounted steam turbine with a through-flow component at one end and a balance drum at the other end, or a front-mounted steam turbine with a through-flow component at each end.

[0022] The application also provides a steam turbine system comprising a front-mounted steam turbine and a main steam turbine, the exhaust steam of the front-mounted steam turbine being delivered to the main steam turbine, and the front-mounted steam turbine adopting the front-mounted steam turbine suitable for high exhaust steam pressure as described above.

[0023] Compared with the prior art, this solution takes a different approach and provides a front-mounted steam turbine. Specifically, its outer cylinder is a split structure formed by a second dividing interface perpendicular to the axis. The open ends of the first outer cylinder body and the second outer cylinder body facing each other have annular flanges and are assembled and fixed by a set of second connecting bolts. Compared with the prior art, the outer cylinder structure of the present application solution can stably withstand exhaust pressures of tens of MPa. At the same time, the two annular skirt parts, the outer wall surface of the inner cylinder and the inner wall surface of the outer cylinder form a low-pressure chamber. The cylinder wall of the outer cylinder between the two annular skirt parts is provided with a pressure balance hole. The pressure balance hole is connected to the low-pressure chamber and is used to connect to the low-pressure area of ​​the steam turbine. The low-pressure chamber can maintain a low pressure, thereby effectively reducing the axial tensile stress on the second connecting bolt. The establishment of a pressure isolation mechanism based on the low-pressure chamber can significantly reduce the scope of high exhaust pressure, improve the overall pressure-bearing performance and connection reliability of the outer cylinder, avoid local stress concentration, and ensure that the outer cylinder of the front-mounted steam turbine can stably withstand very high steam pressures. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 A schematic diagram of a front-mounted steam turbine provided in an embodiment of the present application;

[0025] Figure 2 for Figure 1 AA section view in;

[0026] Figure 3 for Figure 1 A partial enlarged schematic diagram of part B in FIG;

[0027] Figure 4 for Figure 2 A schematic diagram of the outer cylinder shown in ;

[0028] Figure 5 for Figure 4 Partial cross-sectional view of CC;

[0029] Figure 6 for Figure 2 Schematic diagram of the inner cylinder shown in;

[0030] Figure 7 A schematic diagram showing the circumferential limiting relationship of the support positioning protrusion is shown;

[0031] Figure 8 Schematic diagram of the assembly relationship of the limit baffle;

[0032] Figure 9 Schematic diagram of the assembly relationship of the locking block;

[0033] Figure 10 A schematic diagram of another front-mounted steam turbine provided in an embodiment of the present application.

[0034] In the picture:

[0035] Inner cylinder 1, steam inlet chamber 5, first inner cylinder body 1a, second inner cylinder body 1b, first connecting bolt 1c, support positioning protrusion 1d, outer cylinder 2, first outer cylinder body 2a, second outer cylinder body 2b, second connecting bolt 2c, annular skirt 2d, pressure balance hole 2e, support limiting protrusion 2f, axial limiting surface 2f1, auxiliary limiting protrusion 2g, insertion slot 2g1, flow-through component 3, balance drum 4, steam inlet chamber 5, outer wall surface 5a, circular ring 6, sealing ring 7, low-pressure chamber 8, gas inlet 9, rotor 10, end steam seal 11, positioning device 12, steam exhaust pipeline 13, fixing device 14, rotor center 15, first boundary surface 16, flow guide arc surface 17, flow guide round corner 18, limiting baffle 19, stop concave pit 191, locking block 20, stop protrusion 201, mounting hole 202, locking bolt 21, gasket 22, center 15, second boundary surface 23. DETAILED DESCRIPTION

[0036] In order for those skilled in the art to better understand the technical solutions of the present application, the present application will be further described in detail below in combination with the drawings and specific embodiments.

[0037] The front-mounted steam turbine essentially belongs to a back-pressure steam turbine, and its characteristics are that the number of flow-through stages is small, and both the steam inlet pressure and the steam exhaust pressure are at a high level. In the steam turbine system architecture, the front-mounted steam turbine is connected in series with other steam turbines such as a main steam turbine for operation. In the working process, the front-mounted steam turbine first uses steam with high parameters to perform energy conversion and do work, and then delivers the exhaust steam with high pressure and temperature to the subsequent steam turbine for the subsequent steam turbine to continue to expand and do work.

[0038] Generally, the front-mounted steam turbine includes an outer cylinder and an inner cylinder arranged in a nested manner, and the high steam exhaust pressure is mainly borne by the outer cylinder independently.

[0039] In order to ensure that the outer cylinder of the front-mounted steam turbine can stably bear the high steam pressure, systematic optimization and upgrading can be performed from two aspects of cylinder body structure design and material selection. On the one hand, the cylinder body structure is optimized to reasonably distribute the pressure load and avoid local stress concentration; on the other hand, high-strength and high-toughness materials are selected, and the strength parameters of the cylinder body, flanges and connecting bolts and the like are accurately matched according to the pressure working condition, so as to ensure that the components bear pressure in cooperation, effectively prevent the sealing failure problem caused by stress imbalance, and ensure the long-term stable operation of the steam turbine.

[0040] For a unit with higher steam exhaust pressure, the conventional solution is to increase the cylinder wall thickness, select high-strength materials and increase the bolt size, etc., to enhance the cylinder strength and sealing performance. However, these measures will increase the cylinder thermal stress in the start-stop process of the steam turbine, and limited by the material performance and thermal stress constraints, the steam exhaust pressure of the unit is still difficult to be effectively broken through.

[0041] Please refer to Figure 1 and Figure 2 wherein, Figure 1 is a schematic diagram of a front-mounted steam turbine provided by an embodiment of the present application, Figure 2 is Figure 1 A-A cross-sectional view in

[0042] The front-mounted steam turbine provided by the embodiment of the present application is suitable for high exhaust pressure, for example, but not limited to, exhaust pressure of 15 Mpa or more. The front-mounted steam turbine is a steam turbine with a double-layer cylinder structure including an inner cylinder 1 and an outer cylinder 2, and with a through-flow component 3 arranged at one end and a balance drum 4 arranged at the other end. The inner cylinder 1 and the outer cylinder 2 are both split structure.

[0043] As shown in Figure 1 , the outer cylinder 2 is a split structure formed with a second dividing surface 23 perpendicular to the axis, and the open ends of the first outer cylinder body 2a and the second outer cylinder body 2b have annular flanges and are assembled and fixed by a set of second connecting bolts 2c. Compared with the prior art, the outer cylinder 2 structure of the present application can stably withstand tens of megapascals of exhaust pressure.

[0044] As shown in Figure 2 , the inner cylinder 1 is a split structure formed with a first dividing surface passing through the axis, and the first inner cylinder body 1a and the second inner cylinder body 1b are assembled and fixed by a set of first connecting bolts 1c. The middle part of the inner cylinder 1 is an admission area provided with an admission chamber 5, and the admission chamber 5 is formed by the first inner cylinder body 1a and the second inner cylinder body 1b, and on the radially opposite sides of the admission area, there are respectively an admission port 9 in communication with the admission chamber 5.

[0045] Here, the outer wall of the inner cylinder 1 does not have a traditional protruding connecting flange, and each first connecting bolt 1c is embedded in the cylinder wall (the first inner cylinder body 1a and the second inner cylinder body 1b) surrounding the admission chamber 5.

[0046] In a specific implementation, the cylinder wall of the inner cylinder 1 (the first inner cylinder body 1a and the second inner cylinder body 1b) has a reduced diameter section on both sides, and is respectively fixed by a set of interference-fitted rings 6. One ring 6 is fitted on the reduced diameter section of the cylinder wall on the side where the through-flow component 3 is located, and the other ring 6 is fitted on the reduced diameter section of the cylinder wall on the side where the balance drum 4 is located. Overall, based on the two rings 6 and each first connecting bolt 1c, reliable fixation of the first inner cylinder body 1a and the second inner cylinder body 1b is achieved.

[0047] As shown in Figure 1As shown, the first outer cylinder body 2a and the second outer cylinder body 2b are both in a "cup type" structure. The inner wall surfaces of the first outer cylinder body 2a and the second outer cylinder body 2b are respectively provided with annular skirt portions 2d, both of which extend towards the inner cylinder 1 and are respectively adapted to the outer peripheral surface of the corresponding circular ring 6. A plurality of sealing rings 7 are embedded on the annular skirt portions 2d and form a zero-gap fit with the outer peripheral surface of the circular ring 6 through the sealing rings 7.

[0048] In other specific implementations, the sealing rings 7 can also be embedded on the outer peripheral surface of the circular ring 6, and a zero-gap fit between the two can also be constructed, which can be determined according to the overall design requirements of the product, and the embodiments of the present application are not limited.

[0049] In the present embodiment, the two annular skirt portions 2d and the outer wall surface of the inner cylinder 1 and the inner wall surface of the outer cylinder 2 construct a low-pressure chamber 8, and the cylinder wall of the outer cylinder 2 between the two annular skirt portions 2d is provided with a pressure balance hole 2e that communicates with the low-pressure chamber 8, which is used to communicate with the low-pressure area of the steam turbine, and the low-pressure chamber 8 is maintained at a lower pressure, thereby effectively reducing the axial tensile stress of the second connecting bolt. Based on the low-pressure chamber 8, a pressure isolation mechanism is established, which can greatly reduce the range of action of the high exhaust pressure, improve the overall pressure-bearing performance and connection reliability of the outer cylinder 2, and avoid local stress concentration.

[0050] In the present embodiment, the pressure balance hole 2e communicating with the low-pressure chamber 8 is located on the first inner cylinder body 1a side. In other possible implementations, the pressure balance hole 2e can also be located on the second inner cylinder body 1b side, which can be selected according to the overall design requirements of the product, as long as an effective pressure isolation mechanism can be established, which is within the scope of the present application.

[0051] For the second connecting bolt 2c that fixedly connects the first outer cylinder body 2a and the second outer cylinder body 2b, the tensile force borne by it is generated by two parts of pressure load: one is from the steam turbine exhaust pressure P1, which acts on the annular area formed between the outer diameter of the circular ring 6 and the diameter between the rotor 10 steam seal; the other is from the pressure P2 in the low-pressure chamber 8, which acts on the annular area between the outer cylinder 1 inner wall diameter of the low-pressure chamber 8 and the outer diameter of the circular ring 6. It can be understood that the two parts of pressure respectively generate force through different annular area, which jointly determines the stress condition of the second connecting bolt 2c.

[0052] Taking the example that the outer diameters (R2) of the two circular rings 6 are the same and the diameters (R1) of the steam seals on both sides of the rotor 10 are the same, the stress relationship of the second connecting bolt 2c can be expressed as follows:

[0053] S=(P1-Pk)×π·(R2 2 - R1 2) + (P2 - Pk) x π x (R3 2 - R2 2

[0054] Wherein, S is the total tension of all second connecting bolts 2c, P1 is the front turbine exhaust pressure, P2 is the pressure in the low pressure chamber, Pk is the atmospheric pressure, R1 is the radius of the rotor seal, R2 is the radius of the outer surface of the circular ring, and R3 is the radius of the inner wall of the outer cylinder.

[0055] In addition, in order to optimize the arrangement space of the steam inlet chamber 5 of the inner cylinder 1 and the peripheral first connecting bolt 1c, in the specific implementation, the outer wall surface of the steam inlet chamber 5 can be designed as an eccentric structure, as shown in Figure 2 The outer wall surface 5a of the steam inlet chamber 5 on one side of the center line of the two air inlets 9 and the outer wall surface 5a of the steam inlet chamber 5 on the other side of the center line of the two air inlets 9 both gradually decrease from one air inlet 9 to the other air inlet 9, and the wall thickness of the inner cylinder 1 gradually increases. At the same time, the outer wall surface 5a of the steam inlet chamber 5 on one side of the center line of the two air inlets 9 and the outer wall surface 5a of the steam inlet chamber 5 on the other side of the center line of the two air inlets 9 are rotationally symmetrical relative to the rotor center 15, in other words, the air inlets 9 are arranged at the dislocation positions of the size changes of the outer wall surfaces of the steam inlet chambers 5.

[0056] In the embodiment, the first demarcation surface 16 of the first inner cylinder body 1a and the second inner cylinder body 1b is located at the small radial dimension region of the two side wall surfaces 5a, as shown in Figure 2 For example, the horizontal steam inlet structure shown in the figure, the first demarcation surface 16 of the inner cylinder 1 is arranged obliquely, and the first connecting bolt 1c for assembling and fixing the first inner cylinder body 1a and the second inner cylinder body 1b is embedded in the first inner cylinder body 1a and the second inner cylinder body 1b with thicker wall thickness on both sides of the steam inlet chamber 5.

[0057] At the same time, the outer wall surface 5a has a flow guide arc surface 17 at one end of the small radial dimension (thicker wall thickness) and a flow guide round corner 18 at the other end of the large radial dimension (thinner wall thickness). In this way, the steam flow is guided to flow into the steam inlet chamber 5 in a predetermined direction (as shown by the arrow in the figure). Figure 2

[0058] In addition, the inner cylinder 1 and the outer cylinder 2 need to have a stable and reliable locking and fixing relationship in the axial and radial directions. In the specific implementation, the locking and fixing relationship can be realized in different structural forms. In order to improve the assembly process, the locking and fixing in the axial and radial directions can be realized based on the support positioning convex part 1d on the inner cylinder 1 side and the support limiting convex part 2f on the outer cylinder 2 side as the basic structure.

[0059] ​​For example, the support positioning protrusions 1d and the support limiting protrusions 2f are arranged in a one-to-one correspondence, which can realize the axial, radial and circumferential basic positioning between the inner cylinder 1 and the outer cylinder 2. The support positioning protrusions 1d and the support limiting protrusions 2f arranged in groups can be evenly distributed in the circumferential direction, for example but not limited to Figure 2 The ones shown in are spaced at 90° intervals. Figure 3 、 Figure 4 、 Figure 5 and Figure 6 ,in, Figure 3 for Figure 1 The enlarged schematic diagram of part B in the figure is as follows: Figure 4 for Figure 2 The schematic diagram of the outer cylinder is shown in Figure 5 for Figure 4 Partial cross-sectional view of CC, Figure 6 for Figure 2 Schematic diagram of the inner cylinder shown in .

[0060] like Figure 3 As shown, based on the corresponding supporting positioning protrusion 1d and supporting limiting protrusion 2f, the locking and fixing structure also includes an auxiliary limiting protrusion 2g set on the inner wall of the outer cylinder 2, as well as a limiting baffle 19, a locking block 20 and a locking bolt 21.

[0061] Combine Figure 3 、 Figure 4 、 Figure 5 and Figure 6 As shown, the support limiting protrusion 2f and the auxiliary limiting protrusion 2g both protrude radially inward from the inner wall of the first outer cylinder body 2a, and the auxiliary limiting protrusion 2g is axially located on the opening side of the support limiting protrusion 2f close to the first outer cylinder body 2a, and there is an axial spacing L1 between the two. The support limiting protrusion 2f of the outer cylinder 2 has an axial limiting surface 2f1, and the support positioning protrusion 1d protrudes radially outward from the outer wall of the inner cylinder 1, and is pressed against the axial limiting surface 2f1 to form an axial basic limit. After the radial basic limit is formed by the inner wall of the first outer cylinder body 2a, the limiting baffle 19 can be inserted into the axial spacing L1 and axially pressed between the support positioning protrusion 1d and the auxiliary limiting protrusion 2g to limit the support positioning protrusion 1d from falling out. As shown Figure 4 As shown, the auxiliary limiting protrusion 2g has an axially penetrating slot 2g1, so that the supporting positioning protrusion 1d passes through the slot 2g1 and adapts to the supporting limiting protrusion 2f.

[0062] The support and limiting protrusion 2f further includes two circumferential limiting surfaces 2f2 arranged opposite to each other. Figure 5The shown sectional view only shows one circumferential limiting surface 2f2. In a specific implementation, the support limiting protrusion 2f has a groove, and the axial limiting surface 2f1 and the circumferential limiting surface 2f2 can be formed on the groove bottom wall and the groove side wall respectively. In this way, the support positioning protrusion 1d of the inner cylinder 1 can form axial basic limiting by pressing against the axial limiting surface 2f1, and can further form circumferential basic limiting on the support positioning protrusion 1d based on the two circumferential limiting surfaces 2f2 after forming radial basic limiting with the inner wall of the first outer cylinder body 2a.

[0063] In order to further improve the process, in a specific implementation, the support positioning protrusion 1d and the two side axial limiting surfaces 2f1 can have a circumferential spacing L2. Please refer to Figure 7 , which shows a circumferential limiting relationship diagram of the support positioning protrusion 1d.

[0064] In combination with Figure 7 , based on the circumferential spacing L2 between the support positioning protrusion 1d and the two side axial limiting surfaces 2f1, the assembly of the support positioning protrusion 1d and the support limiting protrusion 2f can be facilitated. After the support positioning protrusion 1d of the inner cylinder 1 forms axial basic limiting by pressing against the axial limiting surface 2f1, a gasket 22 can be inserted between the support positioning protrusion 1d and the two side axial limiting surfaces 2f1, and the two inserted gaskets 22 can form circumferential basic limiting on the support positioning protrusion 1d.

[0065] Please refer to Figure 8 and Figure 9 , wherein, Figure 8 is a schematic diagram of the assembly relationship of the limiting baffle 19, Figure 9 is a schematic diagram of the assembly relationship of the locking block 20.

[0066] After the basic limiting of the inner cylinder 1 and the outer cylinder 2 is completed, as shown by the arrow direction in Figure 8 , the limiting baffle 19 can be inserted into the axial spacing L1 between the auxiliary limiting protrusion 2g and the support positioning protrusion 1d (support limiting protrusion 2f). The surface of the limiting baffle 19 facing the insertion slot 2g1 of the auxiliary limiting protrusion 2g has a stop recess 191 for adapting with the locking block 20 and the locking bolt 21.

[0067] After the assembly of the limiting baffle 19 is completed, as shown by the arrow direction in Figure 9 , the locking block 20 can be pressed against the limiting baffle 19, and the two circumferentially opposite groove walls of the insertion slot 2g1 of the auxiliary limiting protrusion 2g abut against the locking block 20. The locking block 20 has a stop protrusion 201 and a mounting hole 202, the stop protrusion 201 can be inserted into the stop recess 191 of the limiting baffle 19, and the locking bolt passes through the mounting hole 202 of the locking block 20 and the bottom thread of the stop recess 191 of the limiting baffle 19 to adapt, realizing the fixation of the limiting baffle 19.

[0068] In this way, based on the circumferentially distributed support positioning protrusions 1d and support limiting protrusions 2f, supplemented by the limiting baffle 19, the locking block 20 and the gasket 22 cooperating with and restricting each other, the center 15 of the inner cylinder 1 and the outer cylinder 2 is kept consistent, and the inner cylinder 1 can only expand or shrink in the radial direction relative to the outer cylinder 2, and cannot produce axial and radial displacement. Through this positioning mode, the concentric state of the inner cylinder 1 and the outer cylinder 2 is effectively ensured.

[0069] The following briefly describes Figure 1 The installation process of the described front-mounted steam turbine is as follows:

[0070] First, the inner cylinder 1 and the rotor 10 are assembled, and the two ends of the inner cylinder 1 are respectively pre-fixed to the rotor 10 through the positioning device 12. Then, the pre-fixed rotor 10 and the inner cylinder 1 are vertically lifted as a whole by a crane, and the first outer cylinder body 2a of the outer cylinder 2 is placed and fixed with the open end facing upward. In this state, the lower side end seal 11 is installed in the first outer cylinder body 2a. Then, the positioning device 12 on the lower side of the inner cylinder 1 and the rotor 10 is removed, and the two are vertically dropped into the first outer cylinder body 2a. In this state, the support positioning protrusions 1d of the inner cylinder 1 and the support limiting protrusions 2f of the first outer cylinder body 2a are closely fitted, realizing radial and axial positioning, and the assembly and fixation of the inner cylinder 1 and the first outer cylinder body 2a are realized through the limiting baffle 19, the locking block 20 and the gasket 22. Then, reliable measures (not shown in the figure) are taken at the bottom of the rotor 10, and the positioning device 12 on the upper side of the rotor 10 and the inner cylinder 1 is removed. Finally, the upper side end seal 11 and the second outer cylinder body 2b are installed using special tools. After the second connecting bolt 2c of the outer cylinder 1 is fastened, the fixing device 14 between the rotor 10 and the outer cylinder 2 is installed at both ends of the cylinder. Based on the fixing device 14, the entire cylinder module can be turned from vertical to horizontal, and the functional requirements of overall transportation can also be met.

[0071] It should be understood that the specific implementation of the functional components such as the through-flow part 3, the balance drum 4, the rotor 10 and the end seal 11 described in the embodiment is not the core of the application, and those skilled in the art can implement it based on the prior art, so it will not be described again.

[0072] In addition to the front-mounted steam turbine described above with one end provided with a through-flow part and the other end provided with a balance drum, the implementation mode of the inner cylinder and the outer cylinder structure provided in the foregoing embodiments can also be used for a steam turbine with a double split-flow through-flow structure. Please refer to Figure 10 , which is a schematic diagram of another front-mounted steam turbine provided in the embodiment of the application. In order to clearly show the difference and connection between the embodiment and Figure 1 the described implementation, the same functional components and structures are shown with the same reference numerals in the figure.

[0073] and Figure 1Compared with the described embodiments, the difference of the present embodiment is that the through-flow part 3 is arranged at both ends of the front-positioned steam turbine. Correspondingly, the steam exhaust pipes 13 at both sides are communicated with each other (not shown in the figure), so as to ensure that the through-flow parts at both ends obtain the same steam exhaust pressure.

[0074] The specific structure of other functional components can be implemented in the same way as Figure 1 the described embodiments. Here, no further description is given.

[0075] In addition to the aforementioned front-positioned steam turbine, the present embodiment further provides a steam turbine system, which comprises the aforementioned Figure 1 or Figure 2 the described front-positioned steam turbine, and further comprises a main steam turbine connected in series with the front-positioned steam turbine, and the steam exhaust of the front-positioned steam turbine is delivered to the main steam turbine.

[0076] In the specific implementation, the thermal coupling and mechanical coupling relationship between the front-positioned steam turbine and the main steam turbine can be implemented by using the prior art, and thus no further description is given.

[0077] In addition, the ordinal numbers "first" and "second" and the like used herein are only used for describing the components or structures with the same function in the technical solutions. It can be understood that the use of the ordinal numbers does not constitute a limitation on the understanding of the technical solutions claimed by the present application.

[0078] The above is only the preferred embodiment of the present application, and it should be pointed out that for those skilled in the art, several improvements and refinements can be made without departing from the principles of the present application, and these improvements and refinements should also be regarded as the protection scope of the present application.

Claims

1. A pre-mounted steam turbine suitable for high exhaust pressure, characterized in that: The front-mounted steam turbine comprises an outer cylinder (2) and an inner cylinder (1) which are nested, and the outer cylinder (2) and the inner cylinder (1) are both split structures, the inner cylinder (1) comprising a first inner cylinder body (1a) and a second inner cylinder body (1b) formed by a first dividing interface (16) passing through the axis, and the first inner cylinder body (1a) and the second inner cylinder body (1b) are fixedly connected by a first connecting bolt (1c) embedded in the cylinder body; the outer cylinder (2) comprises a first outer cylinder body (2a) and a second outer cylinder body (2b) formed by a second dividing interface (23) perpendicular to the axis, and the first outer cylinder body (2a) and the second outer cylinder body (2b) have annular flanges at their facing open ends, and are fixedly connected by a second connecting bolt (2c) inserted through the two annular flanges; Both sides of the cylinder walls of the first inner cylinder body (1a) and the second inner cylinder body (1b) have reduced diameter sections, and are respectively fixed by means of interference-fit circular rings (6); The inner wall surfaces of the first outer cylinder (2a) and the second outer cylinder (2b) are respectively provided with an annular skirt portion (2d), and both of the annular skirt portions (2d) extend toward the inner cylinder (1) and are respectively adapted to the outer peripheral surfaces of the corresponding circular rings (6); The two annular skirt portions (2d) and the outer wall surface of the inner cylinder (1) and the inner wall surface of the outer cylinder (2) form a low-pressure chamber (8). The cylinder wall of the outer cylinder (2) is provided with a pressure balancing hole (2e) that passes through the low-pressure chamber (8). The pressure balancing hole (2e) is used to connect to the low-pressure area.

2. The front-mounted steam turbine according to claim 1, characterized in that: The pressure balance hole (2e) is opened on the cylinder wall of the first outer cylinder (2a).

3. The front-mounted steam turbine according to claim 1 or 2, characterized in that: The annular skirt portion (2d) and the outer peripheral surface of the corresponding circular ring (6) are fitted with zero clearance via a sealing ring (7).

4. The front-mounted steam turbine according to claim 1 or 2, characterized in that: The first inner cylinder (1a) and the second inner cylinder (1b) enclose a steam inlet chamber (5), and radially opposite sides of the steam inlet chamber (5) are respectively provided with air inlets (9) communicating with the steam inlet chamber (5); The radial dimensions of the outer wall surface (5a) of the steam inlet chamber (5) located on one side of the center line connecting the two air inlets (9) and the outer wall surface (5a) of the steam inlet chamber (5) located on the other side of the center line connecting the two air inlets (9) both show a gradually decreasing trend from the air inlet (9) on one side toward the air inlet (9) on the other side, and accordingly, the wall thickness of the cylinder wall of the inner cylinder (1) shows a gradually increasing trend; the outer wall surface (5a) located on one side of the center line connecting the two air inlets (9) and the outer wall surface (5a) located on the other side of the center line connecting the two air inlets (9) are rotationally symmetrical with respect to the rotor center (15); The first interface (16) is located in radially small-sized areas of the outer wall surfaces (5a) on both sides, and the first connecting bolts (1c) are embedded in the cylinder walls on both sides with thicker wall thickness corresponding to the radially small-sized areas.

5. The front-mounted steam turbine according to claim 4, characterized in that: A flow-guiding arc surface (17) is provided at one end of the outer wall surface (5a) with a smaller radial dimension, and a flow-guiding fillet (18) is provided at the other end of the outer wall surface (5a) with a larger radial dimension.

6. The front-mounted steam turbine according to claim 1, characterized in that: The inner cylinder (1) includes a support positioning protrusion (1d), and the support positioning protrusion (1d) protrudes radially outward from the outer wall of the inner cylinder (1); the outer cylinder (2) includes a support limiting protrusion (2f), and the support limiting protrusion (2f) protrudes radially inward from the inner wall of the first outer cylinder body (2a); the inner cylinder (1) and the outer cylinder (2) are fixedly connected by the matching support positioning protrusion (1d) and the support limiting protrusion (2f).

7. The front-mounted steam turbine according to claim 6, characterized in that: The matching support positioning protrusions (1d) and the support limiting protrusions (2f) are arranged in multiple groups and are evenly distributed along the circumference.

8. The front-mounted steam turbine according to claim 6 or 7, characterized in that: The supporting limiting protrusion (2f) has a groove, the bottom wall of the groove is an axial limiting surface (2f1) for matching with the supporting positioning protrusion (1d), and the two circumferentially opposite groove side walls of the groove are circumferential limiting surfaces (2f2) for matching with the supporting positioning protrusion (1d).

9. The front-mounted steam turbine according to claim 8, characterized in that: The outer cylinder (2) further includes an auxiliary limiting protrusion (2g), which protrudes radially inward from the inner wall of the first outer cylinder body (2a) and is axially located on the opening side of the supporting limiting protrusion (2f) close to the first outer cylinder body (2a), with an axial spacing (L1) therebetween. A limiting baffle (19) is provided in the axial spacing (L1) to axially limit the supporting positioning protrusion (1d). The auxiliary limiting protrusion (2g) has an axially penetrating slot (2g1) so that the supporting positioning protrusion (1d) passes through the slot (2g1) and is adapted to the supporting limiting protrusion (2f). A locking block (20) is provided in the slot (2g1), and the locking block (20) and the limiting baffle (19) are fixed by a locking bolt (21).

10. The front-mounted steam turbine according to claim 9, characterized in that: The surface of the limiting baffle (19) facing the slot (2g1) has a stopping recess (191), the locking block (20) has a stopping protrusion (201), and the stopping protrusion (201) is inserted into the stopping recess (191) of the limiting baffle (19).

11. The front-mounted steam turbine according to claim 8, characterized in that: There is a circumferential spacing (L2) between the support positioning protrusion (1d) and the axial limiting surfaces (2f1) on both sides, and an inserting gasket (22) is provided in the circumferential spacing (L2) to circumferentially limit the support positioning protrusion (1d).

12. The front-mounted steam turbine according to claim 1, characterized in that: The pre-mounted steam turbine is a pre-mounted steam turbine with a flow component (3) provided at one end and a balance drum (4) provided at the other end, or a pre-mounted steam turbine with flow components (3) provided at both ends.

13. A steam turbine system, characterized in that: The steam turbine system includes a pre-mounted steam turbine and a main steam turbine, exhaust steam from the pre-mounted steam turbine is delivered to the main steam turbine, and the pre-mounted steam turbine is the pre-mounted steam turbine suitable for high exhaust steam pressure according to any one of claims 1 to 12.

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