Non-contact combined steam seal for turbine shaft end
By designing a non-contact combined steam seal for the turbine shaft end, the reverse pumping effect of the helical teeth and centrifugal disc, as well as the pressure barrier of the helical groove, was utilized to solve the problems of large steam leakage loss at the turbine shaft end and friction of traditional steam seals, thus achieving efficient sealing and improved safety.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- SHENYANG INST OF ENG
- Filing Date
- 2025-07-14
- Publication Date
- 2026-07-14
Smart Images
Figure CN224496534U_ABST
Abstract
Description
Technical Field
[0001] This utility model relates to the field of steam turbine shaft sealing technology, and in particular to a non-contact combined steam seal for steam turbine shaft ends. Background Technology
[0002] Currently, my country's power generation still relies heavily on thermal power. However, with the structural adjustment of my country's thermal power industry and the maturity of thermal power technology, in response to the national call for energy conservation, emission reduction, and green production, vigorously promoting the research, production, and development of supercritical pressure generator units is an inevitable trend. Thermal power generation will undoubtedly continue to develop towards higher efficiency and environmental friendliness. Currently, power plants primarily powered by coal inevitably generate significant pollutant emissions from the combustion of large amounts of coal. With the introduction of low-carbon economic development goals such as carbon peaking and carbon neutrality, finding efficient, energy-saving, green, and low-carbon technologies and equipment is the only way for the power industry to reduce carbon emissions from coal-fired power plants. In thermal power plants, energy conservation and consumption reduction are mainly reflected in the economic efficiency of coal combustion, which is closely related to turbine efficiency.
[0003] Steam seals are specialized devices that prevent steam leakage from the turbine cylinder and air leakage into the cylinder. They are typically installed between moving and stationary components in various flow passages of a steam turbine, improving the overall efficiency of the turbine. Therefore, power generation companies use various types of steam seals to enhance the economics of power generation. According to relevant statistics, steam leakage accounts for 29% of the total stage losses in a steam turbine. Energy losses caused by steam leakage at the turbine shaft end seals can reduce turbine efficiency by 3%-4%, accounting for one-third of the internal losses of the turbine. Steam leakage at the turbine shaft end seals leads to lubricating oil deterioration and component corrosion, seriously threatening unit safety. To reduce steam leakage losses, improve unit operating safety and economy, and solve the problems of rubbing and high maintenance costs associated with traditional steam seals, non-contact combination steam seals at the turbine shaft end are needed to meet these requirements. Utility Model Content
[0004] The purpose of this invention is to provide a non-contact combined steam seal for turbine shaft ends to solve the problems mentioned in the background art.
[0005] To achieve the above objectives, this utility model provides the following technical solution: a non-contact combined steam seal for a steam turbine shaft end, comprising a rotor shaft, a shaft seal air supply chamber, and a shaft seal air extraction chamber disposed on a steam turbine unit, characterized in that it further comprises:
[0006] The first helical tooth, the comb tooth, and the second helical tooth are arranged on the rotor shaft. The first helical tooth and the second helical tooth are used for the reverse pumping effect of the turbine shaft seal to achieve efficient sealing and axial force balance. The comb tooth is used to efficiently block the leakage of working fluid and establish a reverse pressure difference to offset the axial force.
[0007] Centrifugal discs No. 1, No. 2, and No. 3 are fixedly sleeved on the rotor shaft. Each of the centrifugal discs No. 1, No. 2, and No. 3 has a spiral groove arranged in an annular pattern. The centrifugal discs No. 1, No. 2, No. 3, and the spiral grooves are used to actively control the flow pressure effect and establish a pressure barrier, while controlling the leakage of the working fluid.
[0008] Preferably, the first centrifugal disc, the second centrifugal disc, and the third centrifugal disc are fixedly sleeved on the sealing section of the rotor shaft by welding or fitting, and the first centrifugal disc, the second centrifugal disc, and the third centrifugal disc are respectively distributed at the front end of the first helical tooth, the comb tooth, and the second helical tooth.
[0009] Preferably, the materials used for the first centrifuge disc, the second centrifuge disc, and the third centrifuge disc are carbon graphite, ceramic matrix composite materials, or new high-strength materials of high-temperature alloys.
[0010] Preferably, the first helical tooth, the comb tooth, and the second helical tooth are machined on the rotor shaft using a machine tool.
[0011] Preferably, the first helical tooth is designed and machined to be left-handed or right-handed according to the rotation direction of the rotor shaft.
[0012] The beneficial effects of this utility model are:
[0013] This invention can avoid dynamic and static friction during turbine operation, reduce turbine shaft leakage, shorten turbine axial dimensions, save resources, improve unit operation economy, and enhance unit operation safety. Its structure is simple, practical, and easy to promote. Attached Figure Description
[0014] Figure 1 This is a schematic diagram of the non-contact combined steam seal structure for the turbine shaft end proposed in this utility model;
[0015] Figure 2 This is a schematic diagram of the rotor shaft of the non-contact combined steam seal at the turbine shaft end proposed in this utility model.
[0016] Figure 3 This is a schematic diagram of the No. 1 centrifugal disc and spiral groove structure of the non-contact combined steam seal at the turbine shaft end proposed in this utility model.
[0017] In the diagram: 1. Rotor shaft; 2. Shaft seal air supply chamber; 3. Shaft seal air extraction chamber; 4. No. 1 spiral tooth; 5. Comb tooth; 6. No. 2 spiral tooth; 7. No. 1 centrifugal disc; 8. No. 2 centrifugal disc; 9. No. 3 centrifugal disc; 10. Spiral groove. Detailed Implementation
[0018] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present utility model. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Example
[0019] like Figure 1-3 As shown, this embodiment provides a non-contact combined steam seal for the turbine shaft end, including a rotor shaft 1, a shaft seal air supply chamber 2, and a shaft seal air extraction chamber 3 installed on the turbine unit. When the turbine rotor shaft 1 rotates, the auxiliary steam header on the turbine injects clean steam into the shaft seal gap through the shaft seal air supply chamber 2, forming a positive pressure barrier to block the working fluid leakage path. The shaft seal fan on the turbine maintains the pressure gradient and recovers the working fluid by removing the residual steam and air mixture from the shaft seal through the shaft seal air extraction chamber 3. It also includes: a first helical tooth 4, a comb tooth 5, and a second helical tooth 6 installed on the rotor shaft 1. The first helical tooth 4 and the second helical tooth 6 are used for the reverse pumping effect of the turbine shaft seal to achieve efficient sealing and axial force balance. The comb tooth 5 is used to efficiently block the leakage of the working fluid and establish a reverse pressure difference to offset the axial force. A first centrifugal disc 7, a second centrifugal disc 8, and a third centrifugal disc 9 are fixedly sleeved on the rotor shaft 1. Each of the first centrifugal disc 7, the second centrifugal disc 8, and the third centrifugal disc 9 has a spiral groove 10 arranged in a ring. The first centrifugal disc 7, the second centrifugal disc 8, and the third centrifugal disc 9 are used to actively control the flow pressure effect and... A pressure barrier is established while controlling the leakage of the working fluid. When the steam turbine is running, the high-speed rotation of the rotor shaft 1 forces the No. 1 centrifugal disc 7, the No. 2 centrifugal disc 8, the No. 3 centrifugal disc 9, the No. 1 spiral tooth 4, the comb tooth 5, and the No. 2 spiral tooth 6 to rotate at high speed. The centrifugal discs 7, 8, and 9 use the centrifugal force generated by the high-speed rotation to throw the steam in the cylinder radially out along the slot, reducing the amount of steam entering the leakage gap of the No. 1 spiral tooth 4. Then, the pumping effect formed by the rotation of the spiral groove 10 is used to disturb the gas and increase its disorder, thereby reducing steam leakage and achieving a sealing effect.
[0020] To stably fix centrifugal discs 7, 8, and 9 onto rotor shaft 1, they are fixedly fitted onto the sealing section of rotor shaft 1 by welding or fitting. Centrifugal discs 7, 8, and 9 are respectively distributed at the front ends of helical teeth 4, comb teeth 5, and helical teeth 6. Welding or fitting securely fixes centrifugal discs 7, 8, and 9 onto the sealing section of rotor shaft 1.
[0021] To enhance the strength of centrifuge discs 7 (number 1), 8 (number 2), and 9 (number 3), these discs are constructed using novel high-strength materials such as carbon graphite, ceramic matrix composites, or high-temperature alloys. The use of these materials effectively improves their strength, reduces wear, and extends their service life.
[0022] To improve the precision of the first spiral tooth 4, comb tooth 5, and second spiral tooth 6, these teeth were machined on the rotor shaft 1 using a lathe. The high precision achieved by lathe machining of these teeth meets the usage requirements.
[0023] To avoid damage to the steam turbine due to reverse pumping effect, the first helical tooth 4 is designed and machined to be left-handed or right-handed according to the rotation direction of the rotor shaft 1. The first helical tooth 4 is designed and machined to be left-handed or right-handed according to the rotation direction of the rotor shaft 1. It can work with the rotor shaft 1 to form a forward pumping effect, play a sealing role, and prevent the reverse pumping of working medium from damaging the steam turbine.
[0024] Working Principle: During turbine operation, the high-speed rotation of rotor shaft 1 forces centrifugal discs 7, 8, and 9, along with helical teeth 4, comb teeth 5, and helical teeth 6, to rotate at high speed. When comb teeth 5 rotate, multi-stage throttling expansion significantly reduces working fluid leakage while ensuring the safe high-speed rotation of rotor shaft 1. As steam or gas passes through the narrow tooth gaps, the pressure gradually decreases. The inter-tooth eddies create rigidity and damping, suppressing rotor shaft 1 vibration. This effectively blocks working fluid leakage and establishes a reverse pressure differential, counteracting the rotor's axial force. When helical teeth 4 and 6 rotate, they drive the fluid to generate a reverse pumping effect, achieving efficient sealing and axial force balance. The higher the rotational speed, the stronger the sealing effect. The high-pressure zone at the ends of helical teeth 4 and 6 acts on the rotor step surface, extending the thrust bearing life and preventing seal-induced vibration. The centrifugal force of high-speed rotation throws out impurities, reducing wear risk. The rotation of centrifugal discs 7, 8, and 9 actively controls leakage and establishes a pressure barrier through hydrodynamic pressure effect. The rotating spiral groove 10 generates a hydrodynamic pressure effect and establishes a pressure gradient to counteract the axial thrust of rotor shaft 1, while controlling the leakage. The pressure difference established by the spiral groove 10 acts on the area of centrifugal discs 7, 8, and 9, generating a reverse thrust to counteract the axial thrust of rotor shaft 1, reduce the load on the thrust bearing, and precisely guide the leaking steam flow to the turbine recovery system, avoiding disordered leakage impacting the bearing. Furthermore, the centrifugal force generated by high-speed rotation throws the steam in the cylinder radially out along the slot, reducing the steam entering the leakage gap of spiral tooth 4. Finally, the pumping effect formed by the spiral groove 10's screw rotation disturbs the gas, increasing its disorder and reducing steam leakage, thus achieving a sealing effect.
[0025] The above description is only a preferred embodiment of the present utility model, but the protection scope of the present utility model is not limited thereto. Any equivalent substitutions or changes made by those skilled in the art within the technical scope disclosed in the present utility model, based on the technical solution and the inventive concept of the present utility model, should be included within the protection scope of the present utility model.
Claims
1. A non-contact combined steam seal for a steam turbine shaft end, comprising a rotor shaft (1), a shaft seal air supply chamber (2), and a shaft seal air extraction chamber (3) disposed on a steam turbine unit, characterized in that, Also includes: The first helical tooth (4), the comb tooth (5) and the second helical tooth (6) are provided on the rotor shaft (1). The first helical tooth (4) and the second helical tooth (6) are used for the reverse pumping effect of the turbine shaft seal to achieve efficient sealing and axial force balance. The comb tooth (5) is used to efficiently block the leakage of working fluid and establish a reverse pressure difference to offset the axial force. Centrifugal discs 7, 8, and 9 are fixedly sleeved on the rotor shaft (1). Spiral grooves (10) are arranged in a ring on centrifugal discs 7, 8, and 9. Centrifugal discs 7, 8, and 9 and spiral grooves (10) are used to actively control the flow pressure effect and establish a pressure barrier, while controlling the leakage of working fluid.
2. The turbine shaft end non-contact combined steam seal according to claim 1, characterized in that: The first centrifugal disc (7), the second centrifugal disc (8), and the third centrifugal disc (9) are fixedly sleeved on the sealing section of the rotor shaft (1) by welding or fitting. The first centrifugal disc (7), the second centrifugal disc (8), and the third centrifugal disc (9) are respectively distributed at the front end of the first helical tooth (4), the comb tooth (5), and the second helical tooth (6).
3. The turbine shaft end non-contact combined steam seal according to claim 2, characterized in that: The materials used for the first centrifuge disc (7), the second centrifuge disc (8), and the third centrifuge disc (9) are carbon graphite, ceramic matrix composite materials, or new high-strength materials of high-temperature alloys.
4. The turbine shaft end non-contact combined steam seal according to claim 1, characterized in that: The first helical tooth (4), the comb tooth (5) and the second helical tooth (6) are machined on the rotor shaft (1) by machine tool processing.
5. The turbine shaft end non-contact combined steam seal according to claim 1, characterized in that: The first helical tooth (4) is designed and machined to be left-handed or right-handed according to the rotation direction of the rotor shaft (1).