Thanks to the potential of ZRE Gdańsk, the Company is predisposed to the role of general contractor in renovations of power-generating equipment. Our experience and collaboration with scientific institutions and specialist companies of various branches enables suggestion of solutions for customers concerning such problems as: correction of functional parameters of repaired devices, increase of the power output or improving the effectiveness of the power source. The Company is always able to suggest comprehensive service, to assess technical condition of the repaired equipment and essential scope of the renovation, to propose possible modernization, to make successful renovation with use of necessary spare or new parts, until the repaired equipment is put in motion and accepted by the customer.
Technical and economic assumptions
In industrialized European countries, the process of uprating and refurbishing of water plants has been developing intensively since beginning of the 1980s. It is determined by the following factors:
• hydropower potential is utilized in very high degree, during erection process of new power plants
• ecological and financial obstacles,
• as the years go, the profitability of old power plants decreases significantly,
• the progress in the design and manufacturing technology makes it possible to increase the effectiveness of energy conversion process in the offered machinery and equipment,
• the competition on the open power market inclines the power plant users towards rationalization and optimization of power production.
The focal objective of refurbishment and repair is extension of lifetime and improvement of operational characteristics of the machinery, which means increased availability and reduction of the operational expenses. In some cases, the objective of uprating is increasing the power output and/or energy production. This can be achieved by replacing old electro-mechanical equipment of the power plant with a new one, featured by enhanced properties. The mechanical part can be refurbished in such a way that the actual utilization of raw hydro power potential remains unchanged. Technical state of the rotor, guide vanes, bearings and seals is generally of primary significance for the proper operation of hydroelectric machinery. As operational experience indicates damage to these components is the most frequent cause of the failure and poor availability of the machines. In the course of repairs, special attention is paid to the selection of bearing clearance, precision of the rotor installation and alignment of shafts, positioning of rotor blades, and balancing of rotating assembly.
Another significant aspect is reduction or complete elimination of the environmental pollution threat as the result of the leakage of lubricants and oil fractions or grease to water. Uprating of the following bearing equipment depends particularly on use of materials adjusted to water lubrication, or lubricationfree materials:
• lower guide bearing,
• movable connections of guide vanes, lever, couplings and control ring,
• movable connections of rotor blades and elements of the control device, i.e. lever, couplings, cross-head and control rod (in Kapłan turbines).
Undesirable and unavoidable phenomena, arising during the operation, particularly in case of high-speed water turbines, are cavitation and resultant material erosion in draft tubes, chambers, rotor blades and hubs as well as guides. The repair of hydraulic com¬ponents damaged as the result of cavitation pitting requires a labor-consuming overhaul, carried out with use of welding.
Reduction of the availability of a hydraulic machine may be fatigue and hidden material defects, as well as improper operation and maintenance. These factors may be recognized and eliminated, among others on the basis of the diagnostic test results.
Economic, technical and ecological goals of modernization and overhaul of hydroelectric units are determined individually for each power plant.