A modern approach17 January 2013
Ing Bryscejn Milan presents details on the construction and modernization of hydropower plants on the river Labe in the Czech Republic
In recent years there has been a boom in construction and modernization of small hydro plants in the Czech Republic, particularly on the rivers Labe and Vltava. Czech company P&S Spa has participated in this development by supplying technology, especially sluice gates, quick-closure gates, trash rack cleaning machines and turbines. Below you will find details on three interesting projects the company has been involved in over the past year.
Vrané nad Vltavou project
At the end of 2011, the company's activities focused on the design, construction, manufacture, assembly and installation of the coarse racks cleaning machine including railway tracks and trailer container for the Vrané nad Vltavou hydropower plant on the Vltava river, which is operated by CEZ, the largest power company in the Czech Republic.
The cleaning machine at the project is located on the inlet channel on the bridge and is used to remove floating and shifting sediments of larger sizes caught on coarse racks. A brand new atypical machine was manufactured in parts with Energomont in the town of Štetí nad Labem and transported into the test station in the town of Roudnice nad Labem. In collaboration with companies Energomont, Chvalis, Hiab and Elisa, the assembly was completed and stress tests performed, with the machine installed at the project following successful tests. The project also P&S involved in the design, supply and installation of a curved rail tracks for the cleaning machine.
The operating parameters of the cleaning machine were as follows: cleaning depth 11m; rake carrying capacity 2500kg; and railway length of 73m.
Project owner Energo-Pro has realized a comprehensive reconstruction of the Smirice hydropower plant on the river Elbe. Works on the 2.5MW power plant began in 2011. Because of Energo-Pro's previous experiences of working with P&S, the company was invited to collaborate in the development of the turbine inlets and cleaning of inflow water. Closure of the turbine inlets with head of 8.9m and flow of 32m3/sec was originally secured by double sluices of Stoney type, controlled by Gall chains via mechanical gears and electric motors. The original riveted sluice gates needed to be replaced. P&S proposed the construction of welded steel sluice gates sealed with special rubber profiles. Thee gates are controlled by the hydraulic system using linear motors with a diameter of 140mm with piston diameter 90mm and 5400mm stroke. The concept was accepted and implementation took place during the second half of 2011 and the sluice gates and their systems went into operation in early 2012.
Another area in which the investor asked P&S to propose a technical solution was the cleaning of fine and coarse racks at the turbine intakes, including handling of trash. Cleaning of the coarse racks in front of the inlet was achieved with a mobile hydraulic arm equipped with a folding shovel allowing for raking of debris floating along the entire racks up to the weir pillars.
The larger problem was with the proposal of fine racks cleaning. The configuration of the turbine intakes did not allow the cleaning machine to move on straight railway tracks - it was necessary to transport raked trash along a track with a turning angle of 162.5°. Two straight railway tracks connected to a rail curve with radius of about 16m were designed. After a consultation with the Research Institute a cleaning machine with solid wheels was designed. The machine is an electro-hydraulic system with folding arms and folding rake with length of 2.5m to allow cleaning of racks to a depth of about 8m. Raked trash is pulled by the machine into the chute which is emptied by a roll up forehead.
Both cleaning machines were conceptually approved, and constructed and commissioned in March this year.
The operating parameters of the fine racks cleaning machine are as follows: cleaning depth of 6.3m; rake width of 3m; and rake carrying capacity of 500kg.
The operating parameters of the coarse racks cleaning machine are: cleaning depth / range of 5m; rake carrying capacity of 500kg; and railway length of 30m.
Velký Osek project
MVE Velký Osek s.r.o. is developing a small hydroelectric project on the river Elbe at the existing Velký Osek weir and lock. The project features three Kaplan turbines with an output of 3 x 250kW. P&S won the tender for the supply of inlet racks, fine racks cleaning machine and three hydraulically operated draft tube outlet closure gates. All of this equipment must be delivered and operational by the summer 2012.
The cleaning machine is movable on rail tracks with length of 16m with two hydraulically operated arms and hydraulically closed rake of width 4.6m. Maximum cleaning depth is 10m. The machine carries a standard trash container with a capacity of 6.3m3.
Outlet gates are made for closure from the bottom water and they can withstand a static pressure of water at the pump out draft tube at a height of 8.2m. The closure of the water flowing in the ongoing flow is 36m3/sec at maximum head of 2.25m. Closing time of one draft tube is 2 minutes. The gates raise at balanced water levels. The power of the hydraulic motor when handling closure in the flowing water is 118.6kN in the continuous flow of 36m3/sec. Working hydraulic system pressure is 15 ÷ 25 MPa.
The operating parameters of the fine racks cleaning machine are cleaning depth / range of 10m; rake carrying capacity of 500kg; and railway length of 16m.
For more details on the equipment available from P&S please visit www.p-s.cz