CN110206592A - A kind of high temperature high voltage resistant Unitary Impeller-sealing structure suitable for radial flow impeller machinery - Google Patents

Abstract

The invention discloses a high-temperature and high-pressure resistant integrated impeller-seal structure suitable for radial-flow impeller machinery, including stationary vanes, moving vanes, casings, wheel backs, wheel covers, sealed rotors and sealed stators; wherein, several stationary vanes Fixed on the inner wall of the casing, and evenly distributed around the impeller, several moving blades are evenly arranged on the front of the back of the wheel; the wheel cover and the stationary vane are closely attached to form the flow channel of the stationary vane; the wheel cover and the moving blade are matched to form a moving blade The flow channel; the extended section of the front end of the wheel cover constitutes the steam outlet chamber; the sealed rotor is arranged on the back of the wheel, and the sealed stator is fixed on the shell, and the sealed rotor and the sealed stator together form an integrated impeller-sealed structure; the sealed rotor and the sealed stator Leakage gaps are formed between the back of the wheel and the sealed stator and the casing. The invention has the advantages of small wear effect, high temperature and high pressure resistance, and is an impeller-seal integrated structure with simple structure, high safety and economy, and axial thrust balance, and has broad application prospects.

Description

A high temperature and high pressure resistant integrated impeller-seal suitable for radial flow impeller machinery structure

technical field

The invention relates to an impeller mechanical seal structure, in particular to a high temperature and high pressure integrated impeller-sealing structure suitable for radial flow impeller machinery.

Background technique

Compared with the axial-flow impeller machinery, the radial-flow impeller machinery has the advantages of compact structure, simple manufacturing process, low cost, and high efficiency can still be obtained under the design conditions of small flow. Therefore, with the rapid development of engineering technology, radial flow impeller machinery is widely used in power plants with medium and small power. Labyrinth seal is a traditional sealing method. Due to its simple structure and low cost, it is still widely used in turbomachinery.

Generally, radial flow impeller machinery has the characteristics of small size and high speed. In some application scenarios, its design speed is even as high as hundreds of thousands of revolutions per minute. Under the condition of high speed, the ordinary shaft end sealing device can no longer meet the requirements of sealing and safety. Theoretically, in order to reduce air leakage loss, the radial gap between the sealing teeth and the rotor surface will be reduced as much as possible, but when the unit starts and stops and passes the critical speed, the vibration amplitude of the rotor increases, especially the vibration amplitude in the middle of the rotor is the largest. When the vibration amplitude of the rotor exceeds the seal clearance value, it will collide with the seal teeth. Grinding will cause the tips of the sealing teeth to wear, deform or even lose their sealing effect. At the moment of grinding, a large amount of heat will be generated at the contact between the sealing teeth and the rotating shaft, which will cause local overheating of the rotor surface, which may cause serious accidents such as bending of the rotating shaft. In particular, when the temperature and pressure of the working medium in the turbomachinery are high, the stator and the rotor have a differential expansion, and the position of the sealing teeth relative to the boss changes. At the same time, a large axial projection area will generate a huge axial thrust load, and then generate axial movement. This will increase the amount of air leakage, or even destroy the shaft end seal, and the sealing and safety of the entire power unit will be seriously affected.

Contents of the invention

The purpose of the present invention is to address the deficiencies of the prior art and provide a high-temperature and high-pressure resistant integrated impeller-seal structure suitable for radial flow impeller machinery, which has the advantages of small wear, high temperature and high pressure resistance, and is a simple structure. The impeller-seal integrated structure with high safety and economy and balanced axial thrust has broad application prospects.

The present invention adopts following technical scheme to realize:

A high temperature and high pressure resistant integrated impeller-seal structure suitable for radial flow turbomachinery, including stationary vanes, moving vanes, shells, wheel backs, wheel covers, sealed rotors and sealed stators; wherein,

A number of stationary blades are fixed on the inner wall of the casing and evenly distributed around the impeller, and a number of moving blades are evenly arranged on the front of the back of the wheel; the wheel cover and the stationary blade are closely fitted to form a flow channel for the stationary blade; The rotor blade flow channel is formed; the front end extension of the wheel cover forms the steam outlet chamber; the sealed rotor is arranged on the back of the wheel, and the sealed stator is fixed on the inner wall of the shell, and the sealed rotor and the sealed stator are matched without clearance to form an integrated impeller-seal Structure: Leakage gaps are formed between the sealed rotor and the sealed stator, and between the wheel back and the sealed stator and the casing.

The further improvement of the present invention is that the sealed rotor adopts an axial conical boss structure, the ratio of the root diameter of the joint between the sealed rotor and the wheel back to the outer diameter of the wheel back is 0.2 to 0.8, and the ratio of the top diameter of the sealed rotor to the root diameter The ratio of the axial length of the sealed rotor to the outer diameter of the wheel back is 0.3-0.7.

The further improvement of the present invention is that sealing teeth are arranged on the surface of the sealed rotor, the number of the sealing teeth is 4-15, and the ratio of the tooth thickness to the tooth height of the sealing teeth is between 0.1-2.

A further improvement of the present invention is that the sealing teeth include high and low teeth, inclined flat teeth, side teeth and vertical tree structures.

The further improvement of the present invention is that the sealing stator adopts a replaceable structure, which is fixed on the housing through positioning pins, and the sealing stator adopts a stepped structure, the number of steps corresponds to the number of sealing teeth, and the height difference between adjacent steps is the sealing tooth. 0.1 to 0.5 of the tooth height.

A further improvement of the present invention is that the sealed stator is made of high temperature resistant graphite material.

A further improvement of the present invention is that the number of positioning pins is 2-8.

The present invention has following beneficial technical effect:

1. The present invention is reasonable in design, simple in structure, low in cost, convenient in installation, good in reliability, adaptable to harsh working environments, and solves the problem of safety and sealing performance of radial flow impeller mechanical seal structure;

2. The design structure of "zero gap and small wear impact" is adopted between the sealed stator and the sealed rotor, which allows the sealed rotor to wear the sealed stator during rotation, thereby minimizing the leakage cross section formed in the seal and reducing the leakage of the dynamic and static parts of the impeller The gap becomes an adaptive flow channel with high damping and low flow coefficient, effectively reducing air leakage loss, and the sealing performance is better than ordinary shaft end seals;

3. When the unit starts and stops beyond the critical speed, when the operation fails or the seal wears out due to long-term operation, it is only necessary to simply replace the cheap sealed stator, and the sealed rotor will not be affected, and the economy is high. At the same time, compared with the traditional sealing structure, since the sealing stator is made of graphite material, the hardness of the shafting material is relatively low, which eliminates the safety problem caused by the friction between the shafting and the sealing structure when the shafting vibrates.

4. The sealing structure is located on the back of the impeller, which reduces the axial projection area of the force on the back of the impeller. By designing the seal size, the force on the back of the impeller is equal to that of the front of the impeller, which effectively balances the axial thrust of the impeller and improves the safety and reliability of operation. It is also more conducive to the selection of bearings;

5. The sealing boss structure on the back of the impeller greatly increases the axial size of the impeller hub, improves the strength and safety of the impeller when it is working, and enables the radial flow impeller machinery to operate normally in the harsher high temperature and high pressure environment.

6. The impeller-seal structure of the present invention has good processing integrity, easy processing and more implementability.

Description of drawings

Fig. 1 is an axial sectional view of a high temperature and high pressure resistant integrated impeller-seal structure suitable for radial flow turbomachinery according to the present invention;

Fig. 2 is a schematic diagram of the design structure of "zero gap, little wear effect" between the sealed rotor and the sealed stator of the present invention;

Fig. 3 is a three-dimensional schematic diagram of the stationary vane and the integrated impeller-seal structure of the present invention;

Explanation of reference signs:

1. Static blade, 2. Moving blade, 3. Shell, 4. Wheel back, 5. Wheel cover, 6. Steam outlet chamber, 7. Leakage gap, 8. Sealed rotor, 9. Sealed teeth, 10. Seal Stator, 11, positioning pin.

Detailed ways

The embodiments of the present invention will be described in detail below in conjunction with the accompanying drawings. This embodiment is based on the technical solution of the present invention, and provides detailed implementation methods and specific operating procedures, but the scope of protection of the present invention is not limited to the following embodiments. .

As shown in Figures 1 to 3, the present invention provides a high-temperature and high-pressure resistant integrated impeller-seal structure suitable for radial flow turbomachinery, including stationary blade 1, moving blade 2, casing 3, wheel back 4, wheel Cover 5, steam outlet chamber 6, leakage gap 7, sealed rotor 8, sealed teeth 9, sealed stator 10 and positioning pin 11. Among them, a number of stationary blades 1 are fixed on the inner wall of the casing 3 and evenly distributed around the impeller, and a number of moving blades 2 are evenly arranged on the front of the wheel back 4 . The wheel cover 5 fits closely with the stationary vane 1 to form a flow channel for the stationary vane; the wheel cover 5 and the rotor blade 2 are clearance-fitted to form a rotor blade flow channel; the front end extension of the wheel cover 5 forms a cylindrical steam outlet chamber 6 . The sealed rotor 8 is arranged on the back of the wheel back 4, and the sealed stator 10 is fixed on the inner wall of the casing 3. The sealed rotor 8 and the sealed stator 10 together form an integrated impeller-seal structure; between the sealed rotor 8 and the sealed stator 10 and the wheel back 4 together with the sealed stator 10 and the housing 3 form a leakage gap 7 .

The sealed rotor 8 adopts an axial conical boss structure, the ratio of the root diameter of the joint between the sealed rotor 8 and the wheel back 4 to the outer diameter of the wheel back 4 is 0.2-0.8, and the ratio of the top diameter of the sealed rotor 8 to the root diameter is 0.3 ~0.7, the ratio of the axial length of the sealed rotor 8 to the outer diameter of the wheel back 4 is 0.3~0.7. Sealing teeth 9 are arranged on the surface of the sealed rotor 8. The sealing teeth 9 include various structural forms such as high and low teeth, inclined flat teeth, side teeth and vertical tree shapes. The number of sealing teeth 9 is 4 to 15. The number of sealing teeth 9 The ratio of tooth thickness to tooth height is between 0.1 and 2. The sealing stator 10 adopts a replaceable structure, and is fixed on the housing 3 by positioning pins 11. The number of positioning pins 11 is 2 to 8. The sealing stator 10 adopts a stepped structure, and the number of steps corresponds to the number of sealing teeth 9. The height difference between adjacent steps is 0.1-0.5 of the tooth height of the sealing teeth 9, and is made of high-temperature resistant graphite material, so as to ensure the strength and wear resistance of the sealing stator 10 during operation. The back of the wheel 4 and the shell 3 are in clearance fit, and the design structure of "zero clearance and little influence of wear" is adopted between the sealed rotor 8 and the sealed stator 10. The sealed teeth 9 on the sealed rotor 8 are matched with the bosses of the sealed stator 10, When the impeller machine rotates at high speed, the sealing tooth 9 on the sealing rotor 8 is allowed to wear the boss of the sealing stator 10 during the rotation, so as to generate an adaptive gap, and form many sequentially arranged teeth between the sealing rotor 8 and the sealing stator 10 The annular orifice and the annular air chamber minimize the leakage section between the sealed rotor 8 and the sealed stator 10, together with the leakage section between the wheel back 4 and the casing 3, they form an adaptive high damping between the dynamic and static parts of the impeller, Low flow coefficient leakage gap 7 flow channels, the sealing performance is more reliable than ordinary shaft end seals.

Taking the centripetal turbine as an example, the principle and process of the present invention are mainly:

During operation, the high-temperature and high-pressure working medium initially expands through the flow channel of the stator blade, reducing a part of the pressure and temperature, and transforming into a high-speed flowing working medium with a certain airflow angle. Most of the working fluid at the outlet of the stator blade 1 enters the flow channel of the rotor blade along the main channel, and fully expands in the flow channel of the rotor blade, driving the rotor blade 2, the wheel back 4 and the sealed rotor 8 to rotate and do work, and reaches the set value at the outlet of the rotor blade 2. Low temperature and low pressure, then the working fluid is discharged from the steam outlet chamber 6. A small part of the working fluid at the outlet of the stator blade 1 flows into the leakage gap 7, and this part of the leaking working fluid will directly affect the power generation efficiency and operation reliability of the turbine. Radial clearance. In order to reduce the flow rate of the working medium in the leakage gap 7, the sealing tooth 9 on the sealing rotor 8 cooperates with the boss of the sealing stator 10 to form an impeller-seal integrated design structure with "zero clearance and little influence of wear", allowing the sealing The teeth 9 wear the bosses of the sealing stator 10 during rotation, and between the sealing rotor 8 and the sealing stator 10, a plurality of annular holes and annular air chambers arranged in sequence with minimized leakage cross-sections are formed. When the working medium passes through the gap between the first sealing tooth 9 and the sealing stator 10, the flow area decreases sharply, the flow velocity increases, and the pressure energy of the working medium is converted into kinetic energy to form a jet. Then the jet enters the chamber between two adjacent sealing teeth 9 to form a vortex, which partially converts the kinetic energy of the working fluid into heat energy and reduces the flow velocity of the working fluid. In this way, after the working fluid passes through the tooth tip gap of the first sealing tooth 9, the pressure decreases. This process can be approximately regarded as a throttling process, and the specific enthalpy of the working fluid remains unchanged. The thermal process of the working medium passing through the tooth tip gaps of each sealing tooth 9 in the back is the same as passing through the first sealing tooth 9 tooth tip gaps, but the enthalpy drop is getting bigger and bigger, and the speed at the 9 tooth tip places of the sealing teeth is also correspondingly increased. The integrated impeller-seal structure of the present invention with "zero clearance and little influence of wear" makes the leakage gap 7 of the dynamic and static parts of the impeller an adaptive flow channel with high damping and low flow coefficient, effectively reducing air leakage loss, and the sealing performance is better than Ordinary shaft end seal.

When the unit starts and stops and passes the critical speed, the vibration amplitude of the rotor increases. When the vibration amplitude exceeds the seal clearance value, the ordinary shaft end seal will collide with the sealing teeth. Grinding will cause the tips of the sealing teeth to wear, deform or even lose their sealing effect. At the moment of grinding, a large amount of heat will be generated at the contact between the sealing teeth and the rotating shaft, which will cause local overheating of the rotor surface, which may cause serious accidents such as bending of the rotating shaft. However, in the present invention, when the unit starts and stops through the critical speed, when the operation failure or long-term operation produces seal wear, since the sealing stator 10 is made of graphite material, the hardness of the shafting material is relatively low, and the vibration of the shafting system is eliminated. The safety problem caused by the friction of the sealing structure. At the same time, only the cheap sealed stator 10 needs to be simply replaced, and the sealed rotor 8 is not affected, and the reliability and economy are greatly improved. In addition, the tapered boss structure of the sealed rotor 8 on the back of the wheel back 4 acts as a reinforcing rib, which improves the strength and safety of the impeller when it is working, and can make the radial flow impeller machine work in a more severe high-temperature and high-pressure environment. normal operation. At the same time, the impeller-seal integrated structure of the present invention can change the axial force projected area of the wheel back 4 by designing the size of the sealed rotor 8, so that the force on the back of the wheel back 4 is the same as that of the front of the wheel back 4 and the rotor blade 2. The total force is equal to achieve the special effect of balancing the axial thrust of the impeller, which improves the safety and reliability of operation, and is also more conducive to the selection of bearings. The impeller-seal integrated structure of the present invention has simple processing technology, no additional shaft end sealing device is required, and the blank form of forging or investment casting is used during processing to seal the rotor 8, the wheel back 4 and the moving blade 2 made together. Compared with the traditional shaft end seal structure, the impeller-seal integrated structure with "zero clearance and less wear impact" is of great significance for further improving the efficiency, safety, reliability and economy of radial flow impeller machinery.

Claims (7)

1. A high temperature and high pressure integrated impeller-seal structure suitable for radial flow turbomachinery, characterized in that it includes stationary blades (1), moving blades (2), casings (3), wheel backs (4), wheel cover (5), sealed rotor (8) and sealed stator (10); wherein, A number of stationary blades (1) are fixed on the inner wall of the housing (3) and evenly distributed around the impeller, and a number of moving blades (2) are evenly arranged on the front of the wheel back (4); the wheel cover (5) and the stationary blade (1) Closely fit to form the flow path of the stationary blade; the wheel cover (5) and the moving blade (2) are clearance-fitted to form the moving blade flow path; the front end extension of the wheel cover (5) forms the steam outlet chamber (6); the sealed rotor ( 8) Arranged on the back of the wheel back (4), the sealing stator (10) is fixed on the inner wall of the casing (3), and the sealing rotor (8) and the sealing stator (10) cooperate without clearance to form an integrated impeller-seal structure; Leakage gaps (7) are jointly formed between the sealed rotor (8) and the sealed stator (10) and between the wheel back (4) and the sealed stator (10) and the casing (3). 2. A high-temperature and high-pressure resistant integrated impeller-seal structure suitable for radial flow turbomachinery according to claim 1, characterized in that the sealed rotor (8) adopts an axial conical boss structure, and the sealed rotor (8) ) and the ratio of the root diameter at the junction of the wheel back (4) to the outer diameter of the wheel back (4) is 0.2 to 0.8, the ratio of the top diameter to the root diameter of the sealed rotor (8) is 0.3 to 0.7, and the sealed rotor (8) The ratio of the axial length of the wheel back to the outer diameter of the wheel back (4) is 0.3 to 0.7. 3. A high temperature and high pressure resistant integrated impeller-seal structure suitable for radial flow turbomachinery according to claim 1, characterized in that the surface of the sealed rotor (8) is arranged with sealing teeth (9), and the sealing teeth (9) ) are 4 to 15, and the ratio of the tooth thickness to the tooth height of the sealing teeth (9) is between 0.1 and 2. 4. A high temperature and high pressure integrated impeller-seal structure suitable for radial flow turbomachinery according to claim 3, characterized in that the seal teeth (9) include high and low teeth, inclined flat teeth, side teeth and vertical trees shaped structure. 5. A high temperature and high pressure integrated impeller-seal structure suitable for radial flow turbomachinery according to claim 3, characterized in that the seal stator (10) adopts a replaceable structure and is fixed on the On the casing (3), the sealing stator (10) adopts a stepped structure, the number of steps corresponds to the number of the sealing teeth (9), and the height difference between adjacent steps is 0.1-0.5 of the tooth height of the sealing teeth (9). 6. The high temperature and high pressure integrated impeller-seal structure suitable for radial flow turbomachinery according to claim 5, characterized in that the sealing stator (10) is made of high temperature resistant graphite material. 7. A high temperature and high pressure resistant integrated impeller-seal structure suitable for radial flow turbomachinery according to claim 5, characterized in that the number of positioning pins (11) is 2-8.