A 3MW-class full-circle air intake axial flow impulse supercritical carbon dioxide turbine

Abstract

A 3MW-class full-circle intake axial flow impulse supercritical carbon dioxide turbine comprises a main gas regulating combined valve and a turbine body, wherein the turbine body comprises an outer cylinder, an inner cylinder, moving blades, a front bearing box and a rear bearing box; the inner cylinder is arranged in the outer cylinder, the outer cylinder is connected to the shaft seal, the two ends of the shaft are rotatably supported on the front bearing box and the rear bearing box, the main gas regulating combined valve is installed on the turbine body and is connected to the inner cylinder; the turbine body is a unidirectional flow impulse turbine, the rotor comprises an integral moving blade and a shaft, the inner cylinder is a cylindrical inner cylinder, and the intake structure of the inner cylinder is a tangential volute structure. The present invention improves the stability of the rotor shaft system and the rigidity of the rotor, and is suitable for wide load, high-efficiency and stable operation.

Description

Technical Field

[0001] The invention relates to a turbine, in particular to a 3MW-level full-circle air intake axial flow impulse supercritical carbon dioxide turbine, belonging to the field of steam turbines. Background Art

[0002] Supercritical carbon dioxide cycle power generation technology is a strategic and forward-looking key technology. Experimental research is currently the main research method at home and abroad. For supercritical carbon dioxide cycle test benches, the construction cost is positively correlated with the power generation capacity. Therefore, from the perspective of cost saving, the power level of the test bench is generally 3-5MW.

[0003] For 3-5MW supercritical CO2 turbines, according to the current design route, a centripetal structure is generally used. This structure does not have the ability to expand to high-power modeling. This level of supercritical CO2 circulation test bench cannot verify the key technologies of supercritical CO2 axial flow turbines, which greatly weakens the verification capability of the test bench and increases the construction cost of supercritical CO2 circulation. Summary of the invention

[0004] The present invention aims to overcome the deficiencies of the prior art and provides a 3MW-class full-circle air intake axial flow impulse supercritical carbon dioxide turbine.

[0005] A 3MW-class full-circle intake axial-flow impulse supercritical carbon dioxide turbine comprises a main gas regulating combined valve and a turbine body, wherein the turbine body comprises an outer cylinder, an inner cylinder, moving blades, a front bearing box and a rear bearing box; the inner cylinder is arranged in the outer cylinder, the outer cylinder is sealed and connected to the shaft, both ends of the shaft are rotatably supported on the front bearing box and the rear bearing box, the main gas regulating combined valve is mounted on the turbine body and communicated with the inner cylinder; the turbine body is a unidirectional flow impulse turbine, the rotor comprises moving blades and a shaft integrally manufactured, the inner cylinder is a cylindrical inner cylinder, and the intake structure of the inner cylinder is a tangential volute structure.

[0006] Compared with the prior art, the present invention has the following beneficial effects:

[0007] The moving blades of the present invention are made into an integrated rotor with the shaft, and the airway milling process is performed to effectively improve the rotor stiffness and enhance the stability of the rotor shaft system. The turbine body is a unidirectional flow impulse turbine and uses impulse blades. On the one hand, it reduces the inlet and outlet pressure difference of the moving blades and reduces the tip leakage loss; on the other hand, it reduces the axial thrust of the rotor, making it easier to achieve axial thrust balance. The turbine of the present invention is suitable for 3-5MW supercritical carbon dioxide circulation test benches, and is suitable for wide load, high efficiency and stable operation. It can be used to verify the key technologies of axial flow supercritical carbon dioxide axial flow turbines.

[0008] The technical solution of the present invention is further described below in conjunction with the accompanying drawings and embodiments: BRIEF DESCRIPTION OF THE DRAWINGS

[0009] Figure 1 It is a top view of the overall structure of the present invention;

[0010] Figure 2 for Figure 1 The main view;

[0011] Figure 3 It is a main cross-sectional view of the turbine body;

[0012] Figure 4 A schematic diagram of a rotor in which the moving blades and the shaft are made integrally;

[0013] Figure 5 for Figure 3 A local enlarged view of location I. DETAILED DESCRIPTION

[0014] Combination Figure 1-Figure 4 Description: A 3MW level full-circle intake axial flow impulse supercritical carbon dioxide turbine of the present embodiment comprises a main gas regulating combined valve 1 and a turbine body 2, the turbine body 2 comprises an outer cylinder 2-1, an inner cylinder 2-2, moving blades 2-3, a front bearing box 2-4 and a rear bearing box 2-5; the inner cylinder 2-2 is arranged in the outer cylinder 2-1, the outer cylinder 2-2 is sealed and connected to the shaft 2-6, both ends of the shaft 2-6 are rotatably supported on the front bearing box 2-4 and the rear bearing box 2-5, the main gas regulating combined valve 1 is installed on the turbine body 2 and is connected to the inner cylinder 2-2; the turbine body 2 is a unidirectional flow impulse turbine, the rotor comprises moving blades 2-3 and a shaft 2-6 which are made in one piece, the inner cylinder 2-2 is a cylindrical inner cylinder, and the intake structure of the inner cylinder 2-2 is a tangential volute structure.

[0015] As an implementable solution, the turbine is designed with a high speed, the rated speed of the rotor is 16000r / min, and the full-circle air intake method is used to obtain higher turbine efficiency. Affected by the turbine inlet pressure, temperature parameters and flow rate, the blade root diameter is low, the rotor diameter is small, and it is in the form of a slender shaft.

[0016] In order to increase the rotor stiffness and diameter, the traditional T-type blade root assembly structure is cancelled for the moving blades, and an integrated structure of moving blades 2-3 and shafts 2-6 is adopted. The moving blade air duct is milled on the rotor forging, and the throat size of the moving blade is strictly controlled during blade design. The integrated processing is completed using a five-axis CNC machining center.

[0017] In this embodiment, the cylindrical inner cylinder is designed to be a center-divided structure, divided into upper and lower halves, the air intake part adopts a tangential volute air intake structure, and the tangential volute position adopts flange bolt auxiliary sealing, and the outer surface of the inner cylinder 2-2 is provided with a red sleeve ring 4, which is sealed by the red sleeve ring. The design of the above scheme is suitable for ultra-high pressure and ultra-high temperature working parameters, and has excellent sealing performance. In addition, the inner cylinder 2-2 expands evenly, has small thermal stress, is flexible to start and stop, and has excellent turbine variable load performance.

[0018] In a feasible implementation scheme, the turbine body 2 adopts a double-layer cylinder structure, and the outer cylinder 2-1 adopts a center-split flange structure, which is divided into an upper and lower halves, which are connected by bolts. Z-shaped cat claws are involved on both the front and rear sides of the lower half of the outer cylinder 2-1. As the supporting structure of the turbine body on the bearing box, the front bearing box 2-4 and the rear bearing box 2-5 are installed on the base frame 8 with a floor-standing structure. The turbine body 2 is supported on the front bearing box 2-4 and the rear bearing box 2-5 by the cat claws on the outer cylinder 2-1, and the two ends of the integral forged rotor are respectively supported on the front and rear bearings, and the shaft 2-6 on the rotor is connected to the reduction gear box 6 through a diaphragm coupling on the rear bearing side.

[0019] In another specific embodiment, the flange of the outer cylinder 2-1 and the shaft 2-6 are arranged with a dry gas sealing structure 3. The shaft end of the turbine body 2 adopts a single-end dry gas sealing structure to effectively control shaft end leakage and ensure high-efficiency operation of the turbine.

[0020] like Figure 3 and Figure 5 As shown, an abradable sealing coating 5 is arranged between the moving blades 2-3 and the inner cylinder 2-2, and between the stationary blades 2-2-1 and the rotor. The radial seal of the flowing and stationary blades adopts an abradable sealing coating. The coating is allowed to wear during start-up, stop-down and operation, which can effectively reduce the radial sealing gap between the coating and the moving and stationary blades, reduce the air leakage at the blade tip, and ensure the high-efficiency operation of the turbine. This sealing coating is composed of a base layer and a surface layer, wherein the base layer material is NiCrAlY, which plays a role of bonding and transition between the matrix and the surface layer, and has good oxidation resistance and corrosion resistance; the surface layer material is NiCrFeAl-hBN, and the BN phase in the metal matrix is ​​very soft, which can play a role of reducing wear, anti-adhesion and self-lubrication. The coating has moderate hardness, excellent bonding strength and erosion resistance, and does not chemically react with gases such as CO2, and can be used in supercritical carbon dioxide turbine expanders.

[0021] Based on the above scheme, the turbine body 2 adopts the main gas regulating combined valve 1, and the main gas regulating combined valve 1 and the outer cylinder 2-1 are directly connected by flanges. The regulating valve adopts a cage-type regulating valve structure with good linearity and high regulating accuracy, ensuring that the valve can work reliably and accurately adjust the medium flow under large pressure difference, small flow and small opening.

[0022] like Figure 1 and Figure 2 As shown, the output end of the reduction gearbox 4 is connected to a hydraulic dynamometer 7. The power generated by the turbine can be measured in this way.

[0023] The present invention has been disclosed as above with preferred implementation cases, but it is not used to limit the present invention. Any technician familiar with the profession can make slight changes or modifications to equivalent implementation cases with equivalent changes by using the above-disclosed structures and technical contents without departing from the scope of the technical solution of the present invention, which still fall within the scope of the technical solution of the present invention.

Claims

1. A 3MW-class full-circle intake axial flow impulse supercritical carbon dioxide turbine, comprising a main gas regulating combined valve (1) and a turbine body (2), wherein the turbine body (2) comprises an outer cylinder (2-1), an inner cylinder (2-2), moving blades (2-3), a front bearing box (2-4) and a rear bearing box (2-5); the inner cylinder (2-2) is arranged in the outer cylinder (2-1), the outer cylinder (2-1) is sealedly connected to a shaft (2-6), both ends of the shaft (2-6) are rotatably supported on the front bearing box (2-4) and the rear bearing box (2-5), and the main gas regulating combined valve (1) is installed on the turbine body (2) and communicated with the inner cylinder (2-2); Features: The turbine body (2) is a unidirectional flow impulse turbine, the rotor comprises integrally manufactured moving blades (2-3) and a shaft (2-6), moving blade air passages are milled on the rotor forging, the moving blades are impulse blades, the inner cylinder (2-2) is a cylindrical inner cylinder, and the air intake structure of the inner cylinder (2-2) is a tangential volute structure; a dry gas sealing structure (3) is arranged between the flange of the outer cylinder (2-1) and the shaft (2-6); a red sleeve ring (4) is arranged on the outer surface of the inner cylinder (2-2); an abradable sealing coating (5) is arranged between the moving blades (2-3) and the inner cylinder (2-2), and between the stationary blades (2-2-1) and the rotor, the abradable sealing coating (5) is composed of a bottom layer and a surface layer, the bottom layer material is NiCrAlY, and the surface layer material is NiCrFeAl-hBN.

2. According to claim 1, a 3MW-class full-circle intake axial flow impulse supercritical carbon dioxide turbine, characterized in that: The rotor speed is 16000r / min.

3. According to claim 1, a 3MW-class full-circle intake axial flow impulse supercritical carbon dioxide turbine, characterized in that: The shaft (2-6) is connected to the output end of the reduction gear box (6) via a diaphragm coupling.

4. A 3MW level full-circle intake axial flow impulse supercritical carbon dioxide turbine according to claim 3, characterized in that: The output end of the reduction gear box (6) is connected to a hydraulic dynamometer (7).

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