THE LARGEST Heavy SHIP LIFT
The new ship lift at the Three gorges hydroelectric power station is the largest and most technically complex structure of this type in the world. SKF participated in the development of a number of important aspects of this project, which was conducted by the Changjiang Institute of geodesy, planning, design and research.
At first glance, the ship lift at the Three gorges hydroelectric power station looks more like a building than a mechanical device.
It allows you to lift vessels with a displacement of up to 3000 tons to a height of 113 meters. The lifting chamber of the ship lift and its associated mechanisms weigh about 15,500 tons – not surprisingly, it is the largest and most technically complex in the world. Theoretical studies of this ship lift, which is the final part of the Three gorges project, began in the 1950s. its design was completed in 2007, and trial operation began in September 2016.
“The ship lift is designed to speed up the passage of ships through the dam on the Yangtze river,” explains Yu Qingqui, project Manager at the Changjiang Institute of geodesy, planning, design and research (CISPDR), run by the Yangtze river water resources Commission. It now takes just 50 minutes for a 3,000-ton vessel to pass the dam, compared to 3.5 hours when using a five-stage shipping lock.
“The lifter must first be reliable to ensure the safety of ships,” Yu explains – ” and lifting such a heavy chamber to such a height requires precise balancing.” The ship lift at the Three gorges hydroelectric power station is equipped with a counterweight system for balancing the lifting chamber and a rack and pinion system for moving the chamber up and down.
A counterweight weighing 15,500 tons, equivalent to a fully loaded chamber, is divided into 16 sections evenly distributed in two towers on either side of the chamber. The counterweight is connected to the camera by 256 cables through 128 two-wire blocks in the upper part of the towers, which ensures the balance of the camera and the counterweight regardless of the camera position.
Along the entire height of the towers located on either side of the camera, four toothed rails are installed, and four gears in engagement with them provide movement of the camera. Each gear wheel is driven by two electric motors. All drives are synchronized using shafts under the camera. Thanks to the counterbalance system, the gears and rails move approximately 400 tons instead of 15,500 tons, which significantly increases efficiency and reduces energy consumption.
Despite the fact that the camera is balanced, a safety system is still necessary, since even a small accident can lead to a disaster. Following the advice of experts, the CISPDR Institute used a safety mechanism consisting of a hollow half-cylinder with an internal thread and a short screw section (a rotating thrust screw).
When the camera is affected by an unbalanced force, the drive units stop and the safety mechanism locks the camera vertically, preventing a possible accident in the event of an accident. ALREADY at the early stages of designing the ship lift at the Three gorges hydroelectric power station, the cispdr Institute began to cooperate with SKF and appreciated the high quality of its products and services.
After careful analysis and consideration of all alternatives for use in the counterweight system, the drive system and the ship lift safety mechanism, the cispdr Institute selected spherical roller bearings and SKF thrust bearings. The Institute also used SKF spherical plain bearings in the hydraulic cylinders and the camera cable locking system to ensure the safe and reliable operation of the lifting system.
In addition, SKF has supplied hydraulic nuts and hydraulic pumps, as well as other tools for installation and disassembly to improve maintenance efficiency. Freddy pan, head of SKF’s hydropower division, explains that China Three Gorges Corp. is a key client and that SKF has been providing on-site technical consulting and maintenance services for shipping locks at the Three gorges dam since 2012.
Yu says that the official collaboration between the two companies began in 2014. “we are satisfied with the quality of SKF products –” he says. “SKF is a very reliable partner that ensures timely delivery of products.” Cooperation between the companies is developing, and today SKF supplies not only bearings for the ship lift at the Three gorges hydroelectric power station, but also seals for bearing housings and other critical equipment. China Three Gorges Corp. SKF will continue to purchase spare parts after the official commissioning of the ship lift.