A flow structure for medium-pressure steam extraction port of steam turbine

Abstract

A flow structure of a medium-pressure steam extraction port of a steam turbine, specifically relates to a flow structure of the second medium-pressure steam extraction port of a steam turbine, and the present invention is to solve the problem that the flow efficiency before and after the steam extraction port is reduced due to the large steam extraction volume of the second medium-pressure steam extraction port of the steam turbine, the energy loss of the steam extraction chamber is large, and the output of the small steam engine is insufficient, which affects the economic benefits. The front moving blades of the steam extraction port and the rear stationary blades of the steam extraction port are relatively installed in the medium-pressure steam extraction port of the steam turbine, and a moving and stationary blade flow chamber is formed between the front moving blades of the steam extraction port and the rear stationary blades of the steam extraction port, and a steam extraction chamber is formed between the front moving blades of the steam extraction port and the rear stationary blades of the steam extraction port and the medium-pressure cylinder body of the steam turbine, the steam outlet turning point of the steam extraction chamber is arc-shaped, the axial width of the moving and stationary blade flow chamber is 140mm, the blade height of the rear stationary blades of the steam extraction port is consistent with the blade height of the rear stationary blades of the previous stage steam extraction port, and the blade height of the rear stationary blades of the steam extraction port is 1mm-5mm shorter than the blade height of the front moving blades of the steam extraction port. Used to extract part of the steam that has done work in the turbine.

Description

Technical Field

[0001] The invention relates to a flow-through structure of a medium-pressure steam extraction port of a steam turbine, and in particular to a flow-through structure of a second medium-pressure steam extraction port of a steam turbine. Background Art

[0002] A large-power steam turbine is usually equipped with multiple steam extraction ports, the purpose of which is to improve the thermal efficiency and economy of the unit, and to extract part of the steam that has done work from the steam turbine to heat condensate, feed water, and supply deaerators and civil heating. Usually, the second medium-pressure steam extraction port is the fourth stage steam extraction, which is used to supply steam to small machines. Due to its large steam extraction volume, it will have a drastic impact on the flow before and after the steam extraction port, resulting in a decrease in the flow efficiency before and after the steam turbine extraction port, a large energy loss in the steam extraction chamber, and even insufficient output of the small steam turbine, thereby affecting the economic benefits of the owner. Summary of the invention

[0003] In order to solve the problem that the flow efficiency before and after the second steam extraction port of the medium pressure steam turbine decreases due to the large steam extraction volume, the energy loss in the steam extraction chamber is large, and the output of the small steam turbine is insufficient, which affects the economic benefits of the owner, the present invention further provides a flow structure for the medium pressure steam extraction port of the steam turbine.

[0004] The technical solution adopted by the present invention is:

[0005] It includes moving blades in front of the steam extraction port and stationary blades behind the steam extraction port, which are respectively fixedly installed at the two ends of the bottom of the steam extraction chamber, and the moving blades in front of the steam extraction port and the stationary blades behind the steam extraction port are relatively installed in the medium-pressure steam extraction port of the steam turbine. The chamber between the moving blades in front of the steam extraction port and the stationary blades behind the steam extraction port forms a moving and stationary blade flow chamber, and the upper parts of the moving blades in front of the steam extraction port and the stationary blades behind the steam extraction port and the steam turbine medium-pressure cylinder body form a steam extraction chamber, the steam outlet turning part of the steam extraction chamber is processed into an arc shape, the axial width of the moving and stationary blade flow chamber is 140mm, the blade height of the stationary blades behind the steam extraction port is consistent with the blade height of the stationary blades behind the steam extraction port of the previous stage, the blade height of the stationary blades behind the steam extraction port is less than the blade height of the moving blades in front of the steam extraction port, and the blade height of the stationary blades behind the steam extraction port differs from the blade height of the moving blades in front of the steam extraction port by 1mm-5mm.

[0006] Beneficial effects:

[0007] 1. The present invention is based on full three-dimensional aerodynamic analysis and calculation, and jointly calculates the actual flow conditions of steam and blades, adjusts the streamlines of the steam extraction chamber, and refers to the streamline trajectory to obtain a streamlined steam extraction chamber. The turning point of the steam extraction chamber is processed into an arc shape, which can effectively suppress the generation of vortices; the steam extraction port of the steam extraction chamber is processed into an arc shape, so that the airflow transitions smoothly and turns, reducing the generation and divergence of vortices; the connection between the root of the stationary blade and the steam extraction chamber is processed into an arc connection, which effectively allows the steam to smoothly turn from the outlet of the moving blade in front of the steam extraction port to the steam extraction chamber, preventing the generation of large vortices at the steam extraction inlet; the diameter of each arc is obtained through multiple calculations, which conforms to the actual flow conditions of the steam, not only improving the flow efficiency of the medium-pressure cylinder, but also greatly reducing the steam flow loss in the steam extraction chamber from the perspective of aerodynamic economy, better ensuring the steam consumption of the small machine after the four-stage steam extraction, and enabling the owner to generate more economic benefits.

[0008] 2. The present invention increases the effective flow area by increasing the axial width of the flow chamber of the moving and stationary blades.

[0009] 3. Under the premise of ensuring the speed remains unchanged, the height of the stator blades behind the second steam extraction port is reduced, breaking the traditional rule that the height of the stator blades behind the steam extraction port increases step by step. The height of the stator blades behind the second steam extraction port is adjusted to the same height as the stator blades behind the previous steam extraction port, so that the height of the stator blades behind the steam extraction port differs by 0.5mm from the height of the moving blades in front of the steam extraction port, thereby reducing the flow loss in the steam extraction chamber and improving the flow efficiency in the medium-pressure cylinder.

[0010] 4. The present invention is applied to 600MW-class thermal power units, which can increase the stage efficiency of the steam turbine (the efficiency from the moving blades before the steam extraction port to the stationary blades after the steam extraction port) by 0.3%-0.5%, and reduce the total pressure loss by 1.5%-2%, thereby making the unit more efficient during operation and generating more economic benefits.

[0011] 5. The present invention is easy to process and assemble, and has safe and reliable operation. The present invention can be applied to steam turbines of air-cooled units and wet-cooled units of different powers, and can especially meet the steam needs of small machines supplied by extraction steam, thereby meeting the diverse needs of owners and greatly enhancing market competitiveness. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 This is the flow structure diagram of a 600MW steam turbine;

[0013] Figure 2 yes Figure 1 A local enlarged view at point A;

[0014] Figure 3 It is the plan dimension drawing of the steam extraction chamber;

[0015] Figure 4It is a schematic diagram of the flow process of the steam extraction port flow structure, where the arrow direction indicates the gas flow direction; DETAILED DESCRIPTION

[0016] Specific implementation method 1: Combination Figure 1-Figure 4 The present embodiment is described. The present embodiment describes a flow structure of a medium-pressure steam extraction port of a steam turbine, which comprises a moving blade 3 in front of the steam extraction port and a stationary blade 5 behind the steam extraction port. The moving blade 3 in front of the steam extraction port and the stationary blade 5 behind the steam extraction port are relatively installed in the medium-pressure steam extraction port of the steam turbine. The chamber between the moving blade 3 in front of the steam extraction port and the stationary blade 5 behind the steam extraction port forms a moving and stationary blade flow chamber 7. An extraction chamber 1 is formed between the upper parts of the moving blade 3 in front of the steam extraction port and the stationary blade 5 behind the steam extraction port and the medium-pressure cylinder body of the steam turbine. The steam outlet turning part of the steam extraction chamber 1 is processed into an arc shape. Such an arrangement can effectively suppress the generation of vortices. The axial width of the moving and stationary blade flow chamber 7 is 140 mm. With this arrangement, the axial width of the moving and stationary blade flow chamber 7 is increased by 10mm compared with the existing one, thereby increasing the effective flow area. The blade height of the stationary blade 5 behind the steam extraction port is consistent with the blade height of the stationary blade 5 behind the previous stage of steam extraction port. The blade height of the normal stationary blade behind the steam extraction port increases step by step, and generally the difference is about 20mm. For example, the blade height of the previous stage is 200mm, and the blade height of the next stage is about 220mm. The blade height of the stationary blade 5 behind the steam extraction port is less than the blade height of the moving blade 3 in front of the steam extraction port, and the blade height of the stationary blade 5 behind the steam extraction port differs from the blade height of the moving blade 3 in front of the steam extraction port by 1mm-5mm. The reduced blade height value is specifically calculated, referring to the formula To ensure that the axial speed remains unchanged, the blade height is reduced by the value where ν is the speed ratio; c ax is the axial velocity of the airflow; u is the axial velocity of the airflow; such arrangement, while ensuring that the axial velocity of the moving and stationary blade flow chamber 7 remains basically unchanged, thereby reducing the flow loss in the steam extraction chamber 1 and improving the flow efficiency in the medium-pressure cylinder. After the steam is operated from the moving blades 3 in front of the steam extraction port, a part of the steam is extracted into the steam extraction chamber 1, and is supplied to the small steam turbine from the steam extraction outlet through the folded flow in the steam extraction chamber 1, and the remaining part of the steam is still from the moving and stationary blade flow chamber 7 to the stationary blades 5 behind the next stage of the steam extraction port. The present invention is based on full three-dimensional aerodynamic analysis and calculation, adjusts the streamline of the steam extraction chamber 1, and refers to the streamline trajectory design to make the flow distribution more reasonable, greatly reduce the flow loss in the steam extraction chamber 1, and generate more economic benefits. The present invention is applied to a 600MW-level thermal power unit, which can increase the stage efficiency of the steam turbine (the efficiency from the moving blades in front of the steam extraction port to the stationary blades behind the steam extraction port) by 0.3%-0.5%, and reduce the total pressure loss by 1.5%-2%, so that the unit has higher efficiency during operation and generates more economic benefits.

[0017] Specific implementation method 2: Combination Figure 3The present embodiment is described. The present embodiment describes a flow structure of a medium-pressure steam extraction port of a steam turbine. The steam extraction chamber 1 is an integral part. The steam extraction chamber 1 is cast and is easy to process. The outer circle of the steam outlet turning portion of the steam extraction chamber 1 is processed with a first arc 1-1 and a second arc 1-2. The second arc 1-2 and the first arc 1-1 are sequentially connected along the exhaust direction. The inner circle of the steam outlet turning portion of the steam extraction chamber 1 is processed with a third arc 1-3. The rest is the same as the specific embodiment one.

[0018] Specific implementation method three: Combination Figure 3 To explain this embodiment, the flow structure of a medium-pressure steam extraction port of a steam turbine described in this embodiment has a first arc 1-1 with a radius of 65 mm, a second arc 1-2 with a radius of 170 mm, a third arc 1-3 with a radius of 35 mm, a cavity height at the steam extraction outlet of the steam extraction chamber 1 of 50 mm, and a cavity width at the steam extraction inlet of the steam extraction chamber 1 of 90 mm. The diameter of each arc is obtained through multiple calculations and conforms to the actual flow conditions of steam, which not only improves the flow efficiency of the medium-pressure cylinder, but also greatly reduces the steam flow loss in the steam extraction chamber 1 from the perspective of aerodynamic economy, better guarantees the steam consumption of small machines after four-stage steam extraction, and enables the owner to generate more economic benefits. The rest is the same as specific implementation method one or two.

[0019] Specific implementation method four: Combination Figure 3 To illustrate the present embodiment, the present embodiment describes a flow structure of a medium-pressure steam extraction port of a steam turbine, wherein the outer circle of the cavity at the steam extraction outlet of the steam extraction chamber 1 is processed into a fourth arc 1-4, and the radius of the fourth arc 1-4 is 35 mm. Such an arrangement allows the airflow to smoothly transition and turn, thereby reducing the generation and divergence of vortices, and the rest is the same as the specific embodiments one, two or three.

[0020] Specific implementation method five: Combination Figure 2 The present embodiment is described. The flow structure of the medium-pressure steam extraction port of the steam turbine described in the present embodiment further comprises a stationary blade root 6, a stationary blade shroud 8, a moving blade shroud 2 and a moving blade root 4. The stationary blade root 6 is fixedly installed on the upper end of the stationary blade 5 behind the steam extraction port. The stationary blade root 6 is also fixedly connected to one side of the bottom of the steam extraction chamber 1, and the connection between the stationary blade root 6 and the steam extraction chamber 1 is an arc connection. Such an arrangement effectively allows the steam to smoothly turn from the outlet of the moving blade 3 in front of the steam extraction port to the steam extraction chamber 1, preventing The generation of a large vortex at the steam extraction inlet, a stationary blade belt 8 is fixedly installed on the lower end of the stationary blade 5 behind the steam extraction port, and the stationary blade belt 8 is fixedly connected to the bottom end of the moving and stationary blade flow chamber 7, a moving blade belt 2 is fixedly installed on the upper end of the moving blade 3 in front of the steam extraction port, and the moving blade belt 2 is fixedly connected to the other side of the bottom of the steam extraction chamber 1, and a moving blade root 4 is fixedly installed on the lower end of the moving blade 3 in front of the steam extraction port, and the moving blade root 4 is also fixedly connected to the bottom end of the moving and stationary blade flow chamber 7. The rest is the same as the specific implementation mode one, two, three or four.

[0021] Specific implementation method six: Combination Figure 3 To illustrate this embodiment, the flow structure of a medium-pressure steam extraction port of a steam turbine described in this embodiment has an arc radius of 20 mm at the connection between the stator blade root 6 and the steam extraction chamber 1, and the rest is the same as the specific embodiments one, two, three, four or five.

[0022] How it works

[0023] After the steam works from the moving blades 3 in front of the steam extraction port, part of the steam is extracted into the steam extraction chamber 1, and is supplied to the small steam turbine from the steam extraction outlet through the deflected flow in the steam extraction chamber 1, while the remaining steam still flows from the moving and stationary blade flow chamber 7 to the stationary blades 5 behind the next stage of the steam extraction port.

Claims

1. A flow structure for a steam turbine medium-pressure steam extraction port, comprising a steam extraction port front moving blade (3) and a steam extraction port rear stationary blade (5), wherein the steam extraction port front moving blade (3) and the steam extraction port rear stationary blade (5) are relatively mounted in the steam turbine medium-pressure steam extraction port, a chamber between the steam extraction port front moving blade (3) and the steam extraction port rear stationary blade (5) forms a moving and stationary blade flow chamber (7), and a steam extraction chamber (1) is formed between the upper parts of the steam extraction port front moving blade (3) and the steam extraction port rear stationary blade (5) and a steam turbine medium-pressure cylinder body; Features: The steam outlet turning portion of the steam extraction chamber (1) is processed into an arc shape to increase the axial width of the moving and stationary blade flow chamber. The axial width of the moving and stationary blade flow chamber (7) is 140 mm. The height of the stationary blade (5) behind the steam extraction port is consistent with the height of the stationary blade (5) behind the steam extraction port of the previous stage. The height of the stationary blade (5) behind the steam extraction port is less than the height of the moving blade (3) in front of the steam extraction port. The height of the stationary blade (5) behind the steam extraction port differs from the height of the moving blade (3) in front of the steam extraction port by 1 mm to 5 mm. A stator blade root (6) is fixedly mounted on the upper end of the stator blade (5) behind the steam extraction port. The stator blade root (6) is also fixedly connected to one side of the bottom of the steam extraction chamber (1). The connection between the stator blade root (6) and the steam extraction chamber (1) is an arc connection. The radius of the arc at the connection between the stator blade root (6) and the steam extraction chamber (1) is 20 mm. The outer circle of the steam outlet turning point of the steam extraction chamber (1) is processed with a first arc (1-1) and a second arc (1-2), the second arc (1-2) and the first arc (1-1) are connected in sequence along the gas outlet direction, and the inner circle of the steam outlet turning point of the steam extraction chamber (1) is processed with a third arc (1-3).

2. A flow structure for a medium-pressure steam extraction port of a steam turbine according to claim 1, characterized in that: The steam extraction chamber (1) is an integral part.

3. A flow structure for a medium-pressure steam extraction port of a steam turbine according to claim 2, characterized in that: The radius of the first circular arc (1-1) is 65 mm, the radius of the second circular arc (1-2) is 170 mm, the radius of the third circular arc (1-3) is 35 mm, the cavity height at the steam extraction outlet of the steam extraction chamber (1) is 50 mm, and the cavity width at the steam extraction inlet of the steam extraction chamber (1) is 90 mm.

4. A flow structure for a medium-pressure steam extraction port of a steam turbine according to claim 2, characterized in that: A fourth arc (1-4) is machined on the outer circle of the cavity at the steam extraction outlet of the steam extraction chamber (1), and the radius of the fourth arc (1-4) is 35 mm.

5. The flow structure of the medium-pressure steam extraction port of a steam turbine according to claim 1, characterized in that: It also includes a stationary blade shroud (8), a moving blade shroud (2) and a moving blade root (4). The stationary blade shroud (8) is fixedly mounted on the lower end of the stationary blade (5) behind the steam extraction port, the moving blade shroud (2) is fixedly mounted on the upper end of the moving blade (3) in front of the steam extraction port, and the moving blade root (4) is fixedly mounted on the lower end of the moving blade (3) in front of the steam extraction port. The moving blade root (4) is also fixedly connected to the bottom end of the moving and stationary blade flow chamber (7).

Images