High efficiency low grade steam turbine

Abstract

This invention discloses a high-efficiency, low-grade steam turbine. Traditional steam turbines are inefficient and cannot achieve high speeds. In this invention, multiple stages of stationary blades are installed on the stationary blade bearing steel inside the turbine casing; all stationary blades are embedded in the stationary blade bearing steel with inverted T-shaped blade roots; multiple stages of moving blade turbines are installed on the power output shaft; the multiple stages of stationary blades and moving blade turbines form the flow passage of the steam turbine; the centerline positions of the blades of the stationary blades and moving blade turbines are equal, and the blade root diameter decreases progressively; all blades adopt a reaction-type design, with the first half of the stages using narrow chord blades with a reaction degree of 15%-35%; and the second half of the stages using wide chord blades with a reaction degree of 35-70%; a high-pressure water seal is provided at the steam inlet end, and a low-pressure water seal is provided at the exhaust end. This invention improves the isentropic efficiency of the steam turbine unit, generating 20-30% more electricity than traditional steam turbines with the same amount of low-grade saturated steam.

Description

Technical Field

[0001] This invention belongs to the field of steam turbine technology, specifically relating to a high-efficiency, low-grade steam turbine. Background Technology

[0002] Industrial processes generate large quantities of low-grade saturated steam, which is difficult to utilize directly due to its low quality. For example, saturated steam at 105°C is used by many companies for refrigeration via lithium bromide units, for power generation by ORC units, or for power generation by screw expanders, but all suffer from low energy efficiency. Some manufacturers also use traditional steam turbines for power generation, but this is less efficient. For example, with 10 tons of saturated steam at 105°C, a traditional steam turbine would generate approximately 700 kW of power, while a screw expander would generate approximately 500 kW.

[0003] Traditional steam turbines cannot achieve high speeds and cannot realize the design shape of the first-stage blades. They generally use partial air intake to achieve the blade shape design. Furthermore, since the root diameter of the last-stage blade of a condensing steam turbine is the same as that of the first-stage blades, and the blades are relatively tall, the relative tip linear velocity generally does not exceed 410 m / s. Also, due to the yield strength limitation of the blade material, the speed cannot be too high, and the linear velocity cannot exceed the yield limit of the material. Summary of the Invention

[0004] To overcome the shortcomings of existing technologies, this invention provides a high-efficiency low-grade steam turbine, which improves the isentropic efficiency of the turbine unit and generates 20-30% more electricity than traditional turbines with the same low-grade saturated steam.

[0005] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0006] A high-efficiency, low-grade steam turbine includes a casing, and a power output shaft is disposed inside the casing.

[0007] Multiple stages of stationary blades are installed on the stationary blade bearing steel inside the housing; all the blades of the stationary blades are inlaid on the stationary blade bearing steel with inverted T-shaped blade roots.

[0008] The power output shaft is equipped with a multi-stage moving blade turbine; the multi-stage stationary blades and the multi-stage moving blade turbine form the flow passage of the steam turbine;

[0009] The centerline positions of the stationary and moving blades of the turbine are equal, and the root diameter of the blades decreases progressively. All blades adopt a reaction-type design, with the first half of the blades using narrow chord width blades and a reaction degree of 15%-35%; the second half of the blades use wide chord width blades and a reaction degree of 35-70%.

[0010] A high-pressure water seal is provided at the steam inlet end, and a low-pressure water seal is provided at the exhaust end.

[0011] Furthermore, the high-pressure end water seal and the low-pressure end water seal have the same structure, including a sealing body and a sealing carbon ring; the sealing body is fixed on the casing of the turbine at the inlet and outlet ends; the sealing carbon ring is embedded in the sealing body, and the inner wall of the sealing carbon ring contacts the power output shaft, completely isolating the inside of the steam engine from the external atmosphere; the sealing body is provided with a water injection hole, which is connected to an externally provided demineralized water injection port, so that demineralized water is injected into the sealing body to completely seal the passage for air to enter the steam.

[0012] Furthermore, multiple sealing carbon rings are arranged axially along the power output shaft.

[0013] Furthermore, a drain outlet is provided at the steam inlet end to drain away the overflowing demineralized water.

[0014] Furthermore, a condensate drain outlet is provided at the lowest end of the steam inlet on the casing; a second condensate drain outlet is provided at the lowest point of the casing, which is connected to the vacuum section of the condenser, and a negative pressure zone is formed between the casing and the stationary blade bearing steel; a water collection ring is provided on the stationary blade bearing steel after each stage of moving blade turbine; the water collection ring is connected to the negative pressure chamber of the exhaust pipe through the drainage holes on the stationary blade bearing steel, so as to draw away the condensate under negative pressure.

[0015] Furthermore, the moving blade turbine is an integrally milled turbine disk.

[0016] Furthermore, a steam inlet flange is provided at the steam inlet of the housing, and an exhaust flange is provided at the steam outlet; a support bearing one and a support bearing two are respectively provided at both ends of the power output shaft; a thrust bearing is provided on the inner side of the power output end of the power output shaft; and an oil seal one and an oil seal two are respectively provided at both ends of the power output shaft.

[0017] Furthermore, a shaft displacement probe is provided at the end of the power output shaft.

[0018] The beneficial effects of this invention are:

[0019] 1) This invention improves the isentropic efficiency of steam turbine units. In practical applications, the power output of a 10t / h-11t / h generator is 1030-1150kw, and the same amount of steam generates 20-30% more electricity than a traditional steam turbine.

[0020] 2) The present invention is provided with a high-pressure end water seal at the steam inlet end and a low-pressure end water seal at the exhaust end, to ensure that air cannot enter the steam turbine condensing system, reduce the power consumption of the vacuum system, and minimize the negative pressure at the condensing end, thereby improving the steam work efficiency.

[0021] 3) This invention provides multiple water collection rings and drainage holes on the stationary blade bearing steel to discharge the condensate in the water collection rings to the condenser, and provides a condensate discharge port on the casing to smoothly drain the condensate in the unit, ensuring the safe operation of the steam turbine system. Attached Figure Description

[0022] Figure 1 This is a schematic diagram of the overall structure of the present invention;

[0023] Figure 2 This is a flowchart illustrating the hydrophobic process of the present invention.

[0024] Figure 3 This is a schematic diagram of the moving blade turbine structure of the present invention;

[0025] Figure 4 This is a cross-sectional view of the root diameter of the blade of the present invention;

[0026] Figure 5 This is a schematic diagram of the water collection ring of the present invention;

[0027] Figure 6 This is a schematic diagram of the water-sealing structure of the present invention. Detailed Implementation

[0028] The present invention will now be described in detail with reference to specific embodiments.

[0029] This invention provides a high-efficiency low-grade steam turbine that utilizes the direct expansion of low-grade waste heat steam to generate electricity, thereby improving the isentropic efficiency of the turbine unit. The same amount of steam generates 15-10% more electricity than a traditional steam turbine. At the same time, it solves the problem of water erosion of the blades by condensate.

[0030] like Figure 1 As shown, the high-efficiency, low-grade steam turbine of the present invention includes a casing 1, which is integrally cast. A power output shaft 19 is disposed inside the casing 1. A steam inlet flange 2 is disposed at the steam inlet of the casing 1, and an exhaust flange 11 is disposed at the steam outlet. Support bearings 6 and 14 are respectively disposed at both ends of the power output shaft 19. A thrust bearing 15 is disposed inside the power output end 16 of the power output shaft 19. Oil seals 7 and 12 are respectively disposed at both ends of the power output shaft 19. A shaft displacement probe 9 is disposed at the end of the power output shaft 19.

[0031] Inside the housing 1, the stationary blade bearing steel 3 is equipped with multiple stages of stationary blades 4; the stationary blade bearing steel 3 is used to support the stationary blades 4 and is made by integral casting process; all the blades of the stationary blades 4 are inlaid on the stationary blade bearing steel 3 with inverted T-shaped blade roots.

[0032] A multi-stage turbine 5 is mounted on the power output shaft 19. The turbine 5 is a single, milled turbine disk. See details. Figure 3This enables the reasonable assembly of impellers at each stage and the feasibility of large blades in the final stage (small root diameter); the integrally milled turbine disk is mounted on the shaft 19 using an interference fit; the multi-stage stationary blades 4 and the multi-stage moving blade turbine 5 form the flow passage of the steam turbine.

[0033] like Figure 4 As shown, this invention adopts a flow path design concept of equal root diameter rather than equal pitch diameter. The centerline positions of the stationary blade 4 and the moving turbine blade 5 are equal (equal pitch diameter design), and the root diameter of the blades decreases step by step to ensure that the tip linear velocity of the last-stage blade does not exceed the yield limit of the material. All blades adopt a reaction-type design. The blades of the first half of the stages use narrow chord aspect ratio blades with a reaction degree of 15%-35%; the blades of the second half of the stages use wide chord aspect ratio blades with a reaction degree of 35-70%. In this example, taking a 6-stage system, the first three stages use narrow chord aspect ratio blades, and the last three stages use wide chord aspect ratio blades. This design uses reaction-type blade designs for both the stationary and moving blades as much as possible to improve the work efficiency of the airflow within the moving blade cascade and reduce the attenuation of impulse velocity energy.

[0034] This invention features blade root diameters that gradually decrease from the first stage to the last stage, forming an inverted conical shape. This ensures that the length of the last-stage blade remains constant, but the root diameter is relatively low. The first-stage blade root diameter D1 is approximately 1.85 times that of the last-stage blade D0. The continuously decreasing blade root diameter forms an inverted conical shaft diameter. The force of the airflow provides a leftward counter-thrust to the conical surface, thereby counteracting the rightward reaction force exerted on the rotor by the reaction blades, thus replacing the thrust disc of a traditional steam turbine.

[0035] This invention eliminates the traditional turbine pressure regulating stage and part of the steam inlet design, greatly improving the isentropic efficiency of the flow path, achieving an isentropic efficiency of 83%. The flow path design adopts a fully reaction-type blade profile. The design speed of the unit is verified to be 8000 rpm, with a design output power of 1250 kW. The maximum linear velocity at the tip of the last-stage impeller is 343 m / s, and the maximum mechanical stress is 625 MPa. Because the impeller uses double precipitation hardening stainless steel (traditional turbine blades generally use 2Cr13 material, with a maximum yield strength of about 620 MPa), the yield strength reaches 1030 MPa. Therefore, the impeller design remains very safe and reliable at a speed of 8000 rpm.

[0036] The sealing of a small steam turbine is crucial for its vacuum system. Poor sealing can cause a large amount of air to leak into the turbine's exhaust end, increasing the negative pressure at the exhaust end (increasing the energy consumption for vacuuming) and directly affecting the turbine's efficiency and power generation. This invention incorporates a high-pressure water seal 13 at the steam inlet and a low-pressure water seal 8 at the exhaust end to ensure that air cannot enter the turbine's condensation system.

[0037] like Figure 6 As shown, the high-pressure end water seal 13 and the low-pressure end water seal 8 have the same structure, including a sealing body and a sealing carbon ring. The sealing body is fixed on the casing 1 at the inlet and outlet of the steam turbine and is made of stainless steel. The sealing carbon ring is embedded in the sealing body, and the inner wall of the sealing carbon ring contacts the power output shaft 19, completely isolating the inside of the steam engine from the external atmosphere. The sealing body is provided with a water injection hole, which is connected to the external demineralized water injection port to inject demineralized water into the sealing body, completely sealing the passage for air to enter the steam.

[0038] There should be a certain side clearance (0.3-0.5mm) between the side of the sealing carbon ring and the sealing body to ensure that the carbon ring can move. The side contact surfaces of the sealing body and the carbon ring should maintain good flatness and good contact, and the non-contact surfaces between the carbon ring and the sealing body should be minimized.

[0039] To improve the sealing effect, multiple sealing carbon rings are axially arranged along the power output shaft 19, forming multiple sealing spaces. Each space also has a water injection hole connected to an external water injection control pipeline and control valve. During operation, these spaces are filled with water. This water barrier prevents external air from entering the negative pressure end of the turbine, resulting in better turbine vacuum maintenance and reduced power consumption of the vacuum system. The exhaust end maintains a consistently low negative pressure. Water pressure needs to be controlled to ensure that the demineralized water in the seal does not leak from the shaft end to the outer interface of the seal. Since the steam at the steam inlet is under positive pressure, a small amount of water will be discharged from the gap between the sealing carbon rings. A drain port is provided here to remove the overflowing demineralized water. The verification unit of this invention has been in practical application for over two years, maintaining a negative pressure between -95 and -98 kPa, and the unit operates very stably.

[0040] Because saturated steam produces condensate during each stage of expansion, if this condensate is not supplied with water, it will cause water erosion on the blades of subsequent stages, and in severe cases, may lead to water hammer accidents. Figure 5 As shown, the present invention provides a condensate discharge port 17 at the lowest end of the steam inlet on the casing 1 to discharge condensate to the condenser; a second condensate discharge port 18 is provided at the lowest point of the casing 1 to connect to the vacuum section of the condenser, and a negative pressure zone is formed between the casing 1 and the stationary blade support steel 3; a water collecting ring is provided on the stationary blade support steel 3 after each stage of moving blade turbine 5, and a drainage hole is opened at the stationary blade interval of the stationary blade support steel 3; the water collecting ring is connected to the negative pressure chamber of the exhaust pipe through the drainage hole on the stationary blade support steel 3. Under the action of negative pressure, the condensate collected in the water collecting ring is discharged to the condenser, and the condensate in the water collecting ring is smoothly drained out to ensure the safe operation of the steam turbine system. Figure 2 This is a hydrophobic flow chart of the present invention.

[0041] In the description of this invention, unless otherwise explicitly specified and limited, the terms "set," "install," "connect," "link," and "fix" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0042] The content of this invention is not limited to the embodiments listed. Any equivalent modifications made by those skilled in the art to the technical solutions of this invention by reading this specification are covered by the claims of this invention.

Claims

1. A high-efficiency, low-grade steam turbine, characterized in that: Includes a housing (1), and a power output shaft (19) is provided inside the housing (1). Multiple stages of stationary blades (4) are installed on the stationary blade bearing steel (3) inside the housing (1); all the blades of the stationary blades (4) are inlaid on the stationary blade bearing steel (3) with inverted T-shaped blade roots; A multi-stage moving blade turbine (5) is installed on the power output shaft (19); the multi-stage stationary blades (4) and the multi-stage moving blade turbine (5) form the flow passage of the steam turbine; The centerline positions of the stationary blade (4) and the moving blade turbine (5) are equal, and the root diameter of the blades decreases step by step; all blades adopt a reaction type design, with the first half of the blades using narrow chord blades and a reaction degree of 15%-35%; the second half of the blades using wide chord blades and a reaction degree of 35-70%; A high-pressure water seal (13) is provided at the steam inlet end, and a low-pressure water seal (8) is provided at the exhaust end.

2. The high-efficiency, low-grade steam turbine according to claim 1, characterized in that: The high-pressure end water seal (13) and the low-pressure end water seal (8) have the same structure, including a sealing body and a sealing carbon ring; the sealing body is fixed on the casing (1) of the turbine inlet and outlet; the sealing carbon ring is embedded in the sealing body, and the inner wall of the sealing carbon ring is in contact with the power output shaft (19), completely isolating the inside of the steam engine from the outside atmosphere; The sealing body is provided with a water injection hole, which is connected to an external demineralized water injection port. Demineralized water is injected into the sealing body to completely seal the passage for air to enter the steam.

3. The high-efficiency, low-grade steam turbine according to claim 2, characterized in that: Multiple sealing carbon rings are arranged axially along the power output shaft (19).

4. The high-efficiency, low-grade steam turbine according to claim 3, characterized in that: A drain outlet is provided at the steam inlet end to drain away any overflowing demineralized water.

5. A high-efficiency, low-grade steam turbine according to claim 4, characterized in that: A condensate drain port one (17) is provided at the lowest end of the steam inlet on the casing (1); a condensate drain port two (18) is provided at the lowest point of the casing (1), which is connected to the vacuum section of the condenser. A negative pressure zone is formed between the casing (1) and the stationary blade support steel (3); a water collection ring is provided on the stationary blade support steel (3) after each stage of moving blade turbine (5); the water collection ring is connected to the negative pressure chamber of the exhaust pipe through the drainage hole on the stationary blade support steel (3) to draw away the condensate under negative pressure.

6. A high-efficiency, low-grade steam turbine according to claim 5, characterized in that: The moving blade turbine (5) is an integrally milled turbine disk.

7. A high-efficiency, low-grade steam turbine according to claim 6, characterized in that: The housing (1) is provided with a steam inlet flange (2) at the steam inlet and an exhaust flange (11) at the steam outlet; the power output shaft (19) is provided with a support bearing one (6) and a support bearing two (14) at both ends; the power output end (16) of the power output shaft (19) is provided with a thrust bearing (15) inside. Oil seal 1 (7) and oil seal 2 (12) are respectively provided at both ends of the power output shaft (19).

8. A high-efficiency, low-grade steam turbine according to claim 7, characterized in that: A shaft displacement probe (9) is provided at the end of the power output shaft (19).

Images