This presentation uses the model of Kaplan turbine to introduce its main installation procedures. To clearly illustrate the internal structure, all images are sectional views.
- 1.Embedded component installation
- 2.Runner installation
- 3.Installation of Guide Vanes and Head Covers
- 4.Installation of the guide vane driving mechanism
- 5.Install the water guide bearing and shaft seal
- 6.Connection and hoisting installation of the three major components: the runner, the guide cone, and the support cover.
1.Embedded component installation
During the first-phase concrete pouring of the hydropower station powerhouse, the concrete pouring of the draft tube elbow shall be completed, and the relevant components of the draft tube cone section (collectively referred to as the draft tube) shall be installed above the elbow. After fixing the foundation parts such as the draft tube, the runner chamber shall be installed. The runner chamber is the reference component for unit installation, and its installation position must be accurate. The following figure shows the draft tube runner chamber and the runner chamber.
Figure 1. draft tube & runner chamber
A stay ring is installed above the runner chamber. The stay ring for large hydro turbines is large and heavy, so it is assembled on-site. Its center is coaxial with that of the runner chamber. As the foundation component of the entire hydro turbine, the stay ring not only requires high installation accuracy but also must ensure sufficient strength. See Figure 2.
Figure 2—Runner ring of an axial-flow turbine
Metal spiral casings are installed segment by segment along the outer circumference of the stay ring. Once the spiral casings are fully installed, the second-phase concrete filling will be carried out, and the construction of the turbine-generator pit will be completed. Many axial-flow turbines employ concrete spiral casings, and their stay-ring structures also vary somewhat. See Figure 3.
Figure 3—Metal Spiral Casing of an Axial-Flow Turbine
A bottom ring is installed at the lower part inside the seat ring, and this bottom ring features holes for mounting the bearings at the lower ends of the adjustable guide vanes. See the green bottom ring in Figure 4.
Figure 4—Bottom ring of an Kaplan turbine
2. Runner installation
The runner of the large hydro turbine is assembled on-site.
The runner shaft (main shaft) is hollow, with oil pipes running through its interior to control the rotation of the runner blades. The flange at the upper end of the main shaft connects to the hydrogenerator, while the flange at the lower end connects to the runner body. In the middle section of the shaft is a shaft collar, which serves as the rotating part of the guide bearing. See Figure 5. This model has four blades, and the impeller body is equipped with a mechanism that controls blade rotation. The mechanism drives the blade arms to rotate, as shown in Figure 6. The blade rotation mechanism is not shown in the figure. Attach the blades to the blade arms, and install the main shaft onto the runner body. Figure 7 shows the completed runner.
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Figure 5.
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Figure 6.
Figure 7.
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Figure 8. install the Kaplan turbine runner into Runner chamber
3. Installation of Guide Vanes and Head Covers
Install the lower guide vane bearings on the lower shafts of the movable guide vanes, and then install the guide vanes onto the bottom ring one by one.
Figure 9. install the movable guide vanes
A head cover is installed on the upper part of the stay ring. The head cover has a through-hole for mounting the guide vane sleeve (bearing), as shown in Figure 10. Inside the head cover are oil pipes, water pipes, and other components used for lubrication, drainage, and cooling pipe.
Figure 10.Installation of the head Cover for a Kaplan Turbine
Install the guide vane shaft sleeve on the head cover; the sleeve serves as the bearing for the upper shaft of the movable guide vanes, as shown in Figure 11. Inside the sleeve is a bearing bush and a shaft sealing device.
Figure 11.Installation guide vane shaft Sleeve for Kaplan Turbine
In the plant, assemble the support cover with the flow guide cone and lift it into place inside the head cover. The support cover features an installation surface (rail) for the control ring.
Figure 12. Assembly of Support Cover of kaplan turbine
4. Installation of the guide vane driving mechanism
Install the control ring onto the guide rail on the support cover. The control ring can rotate around the turbine shaft axis. On the upper side of the control ring is a large eyelet for connecting the cylinder rod, and on the lower circumference are pins for connecting the guide vane linkage rods.
Install crank arm at the upper end shaft of each guide vane, and connect the crank arms to the pins on the control ring using connecting rods. Adjust the threaded sleeve in the middle of the connecting rods to ensure that all guide vanes rotate at the same angle.
Installation of the guide vane crank arm and connecting rod for a Kaplan turbine, The servomotor seat is installed at the pre-embedded position in the concrete; for some large hydro turbines, the servomotor seat is mounted on the head cover. To install the servomotor, connect the cylinder piston rod to the control ring using the connecting rod.
5. Install the water guide bearing and shaft seal
The guide bearing primarily withstands the mechanical unbalance forces of the runner and prevents shaft oscillation. The guide bearing consists of several key components, including the guide bearing bushing, support screws, bearing base, shaft collar, and oil cooler. The shaft collar is the rotating part mounted on the main shaft, while the other components are stationary. The support screws are mounted on the bearing pedestal’s bushing supports. Six bushings (only four are shown in the sectional view) tightly embrace the shaft collar of the main shaft. The guide bearings are installed inside the oil tank, which is covered by an oil tank lid. Both the oil tank and the oil tank lid are mounted below and above the bearing pedestal, respectively. The bushings are immersed in lubricating oil, and a fan-shaped copper pipe cooler is located at the lower part of the oil tank to prevent the oil temperature from rising. as shown in Figure 16.The guide bearing is installed in the middle of the upper part of the guide cone, as shown in Figure 18.
Figure 16. The strucure of Water guide bearing
The main shaft sealing device prevents pressurized water from the runner chamber from leaking upward through the gap between the main shaft and the guide cone. This model employs a mechanical face seal. Six support pillars are fixed to the sealing bearing (only three are shown in the sectional view); on these pillars—It is fitted with a spring, as shown in Figure 17(a).
The seal ring holder is inserted into the inner ring of the sealing support; the six pillars on the support are inserted into the six holes on the seal ring holder. The holder can move up and down, and a sealing ring is embedded in the gap between the holder and the support to prevent water leakage, as shown in Figure 17(b).
The rotating ring is fixedly mounted on the main shaft without any gap, and it rotates along with the main shaft. A sealing ring is embedded in the seal ring holder, and springs on the support ensure that the sealing ring tightly presses against the lower surface of the rotating ring. As the main shaft rotates, the rotating ring and the sealing ring experience sliding friction. The tightly pressed sealing ring effectively prevents water from leaking. See Figure 17(c).
Figure 17. the detail structure of shaft sealing
The shaft sealing device is installed in the middle at the bottom of the guide cone, as shown in Figure 18.
Figure 18. structure of guide bearing & shaft sealing in the Guide cone body.
6.Complete connection and hoisting installation of the three major components: the runner, the guide cone, and the support cover.
If the on-site workshop height is sufficient and the bridge crane has adequate lifting capacity, a three-body combined lifting method can be adopted. This involves assembling and connecting the three major components—the runner, the guide cone, and the support cover—including installing the runner blade drive mechanism and the operating hydraulic hoses, as shown in Figure 19.
Figure 19. the connection and lifting of three part together
The installation of fixed components eliminates the separate lifting of the rotor, as shown in Figure 8. Only guide vanes, head covers, sleeves, as depicted in Figure 20.
Figure 20. Fixed components installed before the hoisting of the Three-major componnents
after, Lift the three major components as a whole unit and lower them together into position below the machine pit. After they are in place, refer to Figure 12, then proceed with installation in the prescribed sequence.
Overall integrated lifting reduces the amount of installation work required in the machine pit and shortens the installation period for the unit. Currently, newly built power stations increasingly adopt the integrated lifting method. The entire installation process of a turbine is highly complex and demands stringent installation techniques. It often overlaps with the installation of the generator, and depending on the actual site conditions, the installation sequence may even be adjusted. Moreover, turbines of different models have slightly varying structures; the information provided above is for reference only.
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