Drainage system of high-parameter saturated steam turbine

Abstract

A drainage system of a high-parameter saturated steam turbine comprises steam chamber drainage, nozzle chamber drainage and cylinder body drainage. A steam chamber and a nozzle chamber which are communicated are arranged at a steam inlet of the cylinder body, N pressure stages are arranged in the cylinder body in the front-back direction, and each pressure stage comprises a partition plate making contact with steam firstly and fixedly installed on the cylinder body and a movable blade making contact with the steam later and arranged on a steam turbine rotor in a clockwise or anticlockwise rotating mode. The drainage system comprises a steam chamber drainage hole communicated with the lowest point of the steam chamber, a nozzle chamber drainage hole communicated with the lowest point of the nozzle chamber, a cylinder bottom drainage hole and a drainage pipeline, and the cylinder bottom drainage hole is formed behind the first pressure stage to the (N-1) th pressure stage. The steam chamber drain hole, the nozzle chamber drain hole and the cylinder bottom drain hole are connected with a drain pipeline, and a thermodynamic drain valve is mounted on the drain pipeline. The drainage amount can be increased on the premise that the efficiency is not reduced as much as possible, and water erosion of the blades in the warranty period is avoided.

Description

Technical Field

[0001] The utility model relates to the field of saturated steam turbines, and specifically relates to a high-parameter saturated steam turbine drainage system. Background Art

[0002] Since the main steam of a saturated steam turbine has a certain humidity and the main steam is basically high-parameter saturated steam, where high-parameter saturated steam refers to saturated steam above 4.0 MPa, the water content increases rapidly after it enters the steam turbine for work. If the water here is not drained out of the unit, the water droplets will enter the flow passage area of the unit and impact the back arc of the blades at a very high relative speed, causing blade water erosion and reducing the service life of the unit.

[0003] To solve the above problems, there has been a method of gradually increasing drainage holes at the bottom of the diaphragm or machining drainage grooves at the bottom of the cylinder to drain water step by step, and finally discharging the water out of the cylinder through the extraction port or the cylinder exhaust port.

[0004] Gradually increasing drainage holes at the bottom of the diaphragm or machining drainage grooves at the bottom of the cylinder is relatively applicable to non-saturated steam turbine units. However, for saturated steam with high humidity and large water volume during operation, the drainage holes must be increased. But when the drainage holes are increased, the steam does not do work when passing through the drainage holes, which affects the efficiency of the unit. Summary of the Utility Model

[0005] To solve the above technical problems, the utility model provides a high-parameter saturated steam turbine drainage system, which can increase the drainage volume without reducing the efficiency as much as possible and avoid blade water erosion during the warranty period.

[0006] To achieve the above technical purpose, the technical solution adopted is: a high-parameter saturated steam turbine drainage system is arranged on the cylinder body. A steam chamber and a nozzle chamber are connected and communicated at the steam inlet of the cylinder body. N pressure stages are arranged in the cylinder body in the front-back direction. The pressure stage includes a diaphragm that first contacts the steam and is fixedly installed on the cylinder body, and a moving blade that then contacts the steam and is rotatably arranged on the steam turbine rotor in a clockwise or counterclockwise direction. The drainage system includes a steam chamber drainage hole connected to the lowest point of the steam chamber, a nozzle chamber drainage hole connected to the lowest point of the nozzle chamber, a cylinder bottom drainage hole, and a drainage pipeline. The cylinder bottom drainage hole is arranged behind the 1st to the N-1th pressure stages. The steam chamber drainage hole, the nozzle chamber drainage hole, and the cylinder bottom drainage hole are connected to the drainage pipeline, and a thermodynamic steam trap is installed on the drainage pipeline.

[0007] At least one of the diaphragms at the rear end of the utility model is provided with a diaphragm water removal ring. A radial dynamic-static gap that does not affect the rotation of the moving blade is formed between the diaphragm water removal ring and the outer edge of the moving blade, and a diaphragm drainage hole is opened on the diaphragm water removal ring.

[0008] The hydrophobic holes of the partition plate described in the present utility model are arranged to slope downward in the front-back direction.

[0009] The present utility model further includes a drain tank, which is connected to each drain pipeline to collect drain water.

[0010] The beneficial effects of the present utility model are as follows:

[0011] 1. For a saturated steam turbine unit, after the new steam enters the steam chamber, the moisture in the steam is promptly drained in a timely manner, reducing water accumulation, and thus reducing the impact on the entire unit. Then, it undergoes secondary drainage through the nozzle chamber. After entering the cylinder, it is drained again through multiple hydrophobic holes at the bottom of the cylinder, increasing the drainage effect. The opening and closing of the steam trap are controlled by the principle of the thermodynamic steam trap itself, minimizing the impact of drainage on the efficiency of the steam turbine unit to the greatest extent.

[0012] 2. During the operation of the unit, when the steam passes through the partition plate, due to different movement trajectories, the water droplets are blocked into the water removal ring of the partition plate and enter the drainage holes at the bottom of the cylinder through the partition plate drainage system and then into the drain pipeline. This process reduces the moisture entering the subsequent flow passage area, reduces the impact of water droplets on the back arc of the blades, and greatly slows down the erosion rate of the blades.

[0013] 3. The new system of this patent uses a thermodynamic steam trap. The opening and closing of the steam trap are controlled by the principle of the valve itself. Once the water in the drain pipeline reaches a certain position, it automatically opens and closes after the water level drops. This not only reduces the operation difficulty, improves the economy, and extends the service life of the unit, but also effectively reduces the erosion of the moving blades. In addition, the drain water here is demineralized water, and its cost is 20 - 30 yuan / t. When the unit capacity is large, the amount of drain water is very large. Recycling this water can reduce the production cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 is a schematic structural diagram of the present utility model;

[0015] Figure 2 is Figure 1 an enlarged view of part A of

[0016] Figure 3 is Figure 1 an enlarged view of part B of

[0017] Figure 4 is a schematic structural diagram of the pressure stage;

[0018] In the figure: 1. Cylinder body, 101. Steam chamber drain hole; 102. Nozzle chamber drain hole; 103. Drain pipeline; 104. Thermodynamic trap; 105. Drain tank; 106. Partition water removal ring; 107. Partition drain hole, 108. Steam chamber; 109. Nozzle chamber; 110. Pressure stage; 111. Partition; 112. Moving blade; 113. Cylinder bottom drain hole. Specific implementation mode

[0019] The following presents the preferred embodiments of the utility model in conjunction with the accompanying drawings to elaborate in detail on the technical solutions of the utility model. Here, corresponding drawings will be provided to explain the utility model in detail. It should be particularly noted that the preferred embodiments described herein are only for explaining and interpreting the utility model and are not used to limit or restrict the utility model.

[0020] The specific implementation steps of a high-parameter saturated steam turbine drainage system are as follows: As Figure 1 When the new steam enters the steam chamber 108, water will accumulate at the bottom. The water is discharged in a timely manner through the bottom steam chamber drain hole 101. Then the steam enters the nozzle chamber 109, where water will also accumulate. The accumulated water is discharged in a timely manner through the nozzle chamber drain hole 102 at the bottom of the nozzle chamber. The accumulated water in the cylinder is discharged through the cylinder bottom drain hole 113 behind the pressure stage. In addition, the drain water at each stage is discharged into the drain tank through the drain pipelines of each branch through the automatic trap for recycling and reuse.

[0021] A high-parameter saturated steam turbine drainage system that can achieve the above steps includes steam chamber drainage, nozzle chamber drainage, and cylinder body drainage. At the steam inlet of the cylinder body 1, a steam chamber 108 and a nozzle chamber 109 are provided in communication. Steam sequentially passes through the steam chamber 108 and the nozzle chamber 109 and enters the cylinder body 1. N pressure stages 110 are provided in the cylinder body 1 in the front-back direction. The pressure stage 110 includes a partition 111 that first contacts the steam and is fixedly installed on the cylinder body 1, and a moving blade 112 that later contacts the steam and is rotatably arranged on the steam turbine rotor in a clockwise or counterclockwise direction. An axial dynamic surface gap L is provided between the partition 111 and the moving blade 112 in the front-back direction.

[0022] As Figure 1 、 Figure 4As shown in the figure, the hydrophobic system includes a steam chest drain hole 101 communicating with the lowest point of the steam chest 108, a nozzle chamber drain hole 102 communicating with the lowest point of the nozzle chamber 109, a cylinder bottom drain hole 113, and a drain pipeline 103. When the steam turbine starts, the steam chest is preheated with steam first. Since the saturated steam has a high humidity and a large amount of condensate is generated during preheating, in order to drain the condensate in time, a steam chest drain hole 101 is provided at the lowest point of the steam chest to drain the condensate in time. After the steam chest 108 is preheated, the steam turbine starts. During this process, a large amount of condensate is also generated in the nozzle chamber 109. In order to facilitate the timely drainage of the condensate in the nozzle chamber, a nozzle chamber drain hole 102 is provided at the lowest point of the nozzle chamber to drain the condensate in time. The cylinder bottom drain hole 113 is arranged behind the 1st to the (N - 1)th pressure stages 110. After the steam enters the steam turbine cylinder to work, its water content increases rapidly. If the water here is not drained, it will cause serious water erosion of the moving blades of the unit, and also cause a large temperature difference between the upper and lower cylinders, affecting the operation and the service life of the steam turbine. The steam chest drain hole 101, the nozzle chamber drain hole 102, and the cylinder bottom drain hole 113 are connected to the drain pipeline 103 with a larger diameter to drain the condensate out of the cylinder in time. A thermodynamic trap 104 is installed on the drain pipeline 103.

[0023] Working principle of the thermodynamic trap 104: The thermodynamic trap 104 is based on Bernoulli's thermodynamic principle. By utilizing the different thermodynamic characteristics of steam and condensate, it causes changes in kinetic energy and potential energy, resulting in changes in static and dynamic pressures. This causes the differential pressure above and below the moving part, the valve disc, to change, starting the opening and closing of the valve disc, thereby achieving the purpose of blocking steam and draining water.

[0024] As Figure 1 , Figure 4 shown in the figure, to further improve the drainage effect, in the low-pressure part of the vacuum area at the rear end inside the cylinder, the dynamic and static clearances between the diaphragm stationary blades and the impeller moving blades are increased. At least one diaphragm 111 located at the rear end is designed with a diaphragm water removal ring 106. A radial dynamic and static clearance 114 that does not affect the rotation of the moving blade 112 is formed between the diaphragm water removal ring 106 and the outer edge of the moving blade 112. The radial dynamic and static clearance is represented as H in the figure. For example, Figure 1 as shown in the figure, the diaphragm water removal ring 106 is installed on the last four pressure stages. Diaphragm drain holes 107 are arranged radially on the diaphragm water removal ring 106 to drain the water in the steam at the outlet of the diaphragm 111 in time before it enters the moving blade, reducing the water erosion of the moving blade. The moving blade 112 is made of a water erosion-resistant material, and Stellite alloy is inlaid or laser hardened on the outside of the moving blade inlet. The diaphragm drain holes 107 are arranged obliquely downward in the front-back direction, which can avoid obstacle positions and drain water better.

[0025] After the new steam enters the steam chamber 108, it is drained once. Subsequently, it enters the nozzle chamber 109 and is drained again. After passing through the nozzles, there is a drainage after the rear of the 1st to the (N - 1)th pressure stages 110. Finally, it is discharged into the drain tank 105 through each drain pipeline 103 for recycling.

[0026] The above are only the preferred examples of the present utility model, and are not used to limit or define the present utility model. For those skilled in the art of research or technology, various changes and modifications can be made to the present utility model. Any modification, equivalent replacement, improvement, etc., made within the spirit and principle of the present utility model shall be included within the scope of protection claimed by the present utility model.

Claims

1. A high-parameter saturated steam turbine drainage system is arranged on the cylinder body (1). A steam chamber (108) and a nozzle chamber (109) are provided at the steam inlet of the cylinder body (1) and are connected and communicated. N pressure stages (110) are arranged in the cylinder body (1) in the front-back direction. The pressure stage (110) includes a diaphragm (111) that first contacts the steam and is fixedly installed on the cylinder body (1), and a moving blade (112) that later contacts the steam and is rotatably arranged on the steam turbine rotor in a clockwise or counterclockwise direction. It is characterized in that: The hydrophobic system includes a steam chest drain hole (101) communicating with the lowest point of the steam chest (108), a nozzle chamber drain hole (102) communicating with the lowest point of the nozzle chamber (109), a cylinder bottom drain hole (113), and a drain pipeline (103). The cylinder bottom drain hole (113) is arranged behind the 1st to the (N - 1)th pressure stages (110). The steam chest drain hole (101), the nozzle chamber drain hole (102), and the cylinder bottom drain hole (113) are connected to the drain pipeline (103), and a thermodynamic trap (104) is installed on the drain pipeline (103).

2. The high-parameter saturated steam turbine drainage system according to claim 1, characterized in that: At least one of the rear diaphragms (111) is provided with a diaphragm water removal ring (106). A radial static-dynamic clearance (114) that does not affect the rotation of the moving blades (112) is formed between the diaphragm water removal ring (106) and the outer edge of the moving blades (112). A diaphragm drain hole (107) is formed in the diaphragm water removal ring (106).

3. The high-parameter saturated steam turbine drainage system according to claim 2, characterized in that: The diaphragm drain hole (107) is arranged to incline downward in the front-rear direction.

4. A high-parameter saturated steam turbine drainage system according to claim 1, characterized in that: It further includes a drain tank (105). The drain tank (105) is connected to each drain pipeline (103) for collecting the hydrophobic water.

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