Norconsult Norconsult The 200 MW Kidatu power plant is located on - PDF document

Rehabilitation of Kidatu Power Plant Project Presentation Norconsult Norconsult

The 200 MW Kidatu power plant is located on the Great Ruaha River in the region of Morogoro in central Tanzania about 280 km west of Dar es Salaam. The construction of Kidatu power scheme was started in the early seventies with the commissioning of the two first units at 50 MW each in 1975. The last two 50 MW units were commissioned in 1980, making a total installation of 200 MW. Since its initial inauguration in 1975, Kidatu power plant has played a very important role in Tanzania’s electric power supply. When the first phase of the Kidatu rehabilitation project started in 1991, Kidatu’s installation represented more than 50% of the installed capacity in Tanzania. Today, Tanzania has a total installation of about 800 MW, of which Kidatu generates about 50% of the total energy consumption in Tanzania. KIDATU KEY DATA 80 000 km 2 - Catchment area - River run-off (mean value) 191 m3/s - Discharge capacity 140 m3/s - Turbine capacity 4x52,5 MW - Generator capacity 4x60 MVA - Annual generation 1,2 TWh - Annual asset creation 11 billion SEK (at average consumer sales tariff)

Machine hall before and after rehabilitation Rehabilitation of Kidatu Power Plant A successful rehabilitation of Kidatu power plant has increased the annual production with approximately 5.5 GWh. State of the art technology was successfully introduced with a fully integrated efficiency optimisation program, which is unique in the hydropower world. Kidatu is an underground power station about 180 tonnes, rotating at a speed with four vertical Francis units of 50 MW of 375 revolutions per minute each and designed for a total discharge Power from the generators is fed to of about 140 m 3 per second. The power the single-phase transformers located plant utilises a maximum head of 175 m in the powerhouse cavern via 10.5 kV between the intake and the tailrace. The polyethylene insulated cables. From the intake reservoir has a live storage of 125 main 220 kV transformers the power million m 3 contained by a 40 m high earth is led through an 85 m vertical cable and rockfill dam with a crest length of shaft to the pothead yard via 220 kV oil 350 m. Three spillway sector gates have a immersed power cables. There are four total capacity of 6,000 m 3 /s. The headrace 220 kV overhead lines connecting to the tunnel is unlined with a length of 9.6 km. 220 kV switchyard. The tailrace tunnel has a length of 1.0 km. Although not very old after only A vertical steel-lined penstock twenty years of operation, Kidatu feeds each of the Francis stainless steel had already reached a stage where turbines. Litostroy Lubjana made the rehabilitation became necessary in order two first units while Voith made the to maintain a reliable power supply to two last units designed for about 35 m 3 / Tanzania. The severe damage of generator second each. Rade Koncar in Zagreb, 1 in 1990 triggered the Urgent Repairs Yugoslavia manufactured the generators. Project - Phase 1. Each unit has a total rotating mass of Tailrace into Great Ruaha river 3

Generator under rehabilitation New excitation system The Project THE URGENT REPAIRS PROJECT- REHABILITATION OF KIDATU PHASE I The rehabilitation of the Kidatu power POWER PLANT - PHASE II plant, phase II project, has a total budget Phase I, known as the urgent repairs The rehabilitation of the Kidatu was of about SEK 103 million (about Euro project, was started in 1991 with the continued with Phase II in 1995 when 10 million ) jointly funded by Sida and main objective to carry out urgent Norconsult was awarded a contract for NORAD with Sida as the lead donor. repairs of the damaged generating unit 1. consulting services. The project was contracted with turnkey The project included a complete repair The feasibility study dated March deliveries. The duration of the rehabilitation of generator 1 and replacement of the 1996 recommended that TANESCO activities was considerably extended till rotating exciters with a static excitation perform a number of actions to about four years in order to accommodate system. increase the overall power supply for related operational interference and Phase 1 was successfully completed reliability in Tanzania. Sida decided other unforeseen difficulties. within a year’s period in December 1993 to assist with financial support to the The rehabilitation project was at a total 1993 cost of SEK 25 million. implementation of the most important performed with only one unit out of parts through the rehabilitation of the operation at a time due to generation Kidatu power plant - phase II project. constraints in the Tanzanian grid. Tender documents were prepared, and The Contractors provided the following contracts were signed on experienced supervisors with 10 June 1998: responsibility for guiding and instructing 1. Rehabilitation of the mechanical the skilled and unskilled manpower works: Kvaerner Energy AS helpers provided by TANESCO. This (now GE Hydro) arrangement was carried out in order 2. Rehabilitation of the electrical works to minimise project costs and to ABB Kraft AS (now Alstom Power) improve the on the job training. 3. Delivery and installation of control New pipline insulation and protection equipment.: Siemens AS (now Voith Siemens) 4. Improvements of the Maintenance Management System (MMS): Norconsult AS 5. Consultancy Services: Norconsult AS Sandblasting exhaust arrangement Cavitation on the runner 4

Francis runner Rehabilitation of turbine 2 system, there was a need to improve MECHANICAL WORKS cavern, thus sucking the dust and sand the working environment. New particles out through the pothead yard. Vertical Turning Lathe (VTL) insulation materials made of armaflex The cavitation of the runners 1 and 2 Turbine Rehabilitation were purchased and installed by were severe, and considerable repair TANESCO labour force. The result Almost all the blades of the turbine works were foreseen. In order to was extremely positive, and the runners 1 and 2 had severe cavitation improve the quality of the repair works, condensation and dripping problem is both on the inlet and suction side. it was decided to install a vertical now almost gone. Some of these damages were as large turning lathe (VTL) machining mill to as 300 by 100 mm and almost 20 mm ensure a proper machining of the large GENERATOR WORKS deep. When grinding, some of the rotating parts. cavities proved to be almost through A main problem at Kidatu was the The VTL was located on the the blade. Consequently, it became capacity limitation of the generators due machine hall floor enabling the use of difficult to repair with a good and to heating problems in the bearings, the over-head crane to move heavy lasting result. reducing the available capacity to approx- parts into the VTL and back without The runners were grinded and imately 175 MW of continuous load. further need of mobile cranes etc. weld-repaired at the Kidatu, and new Moreover, the bearings had severe facing plates were fitted. oil leakages and some were leaking up Surface Treatment to two litres of oil per day. The slip- The feasibility study had revealed an New Turbine Governors ring housing was ventilated from the urgent need to recondition the steel generator pit, and as a result carbon New turbine governors have been lined waterways and pressure shafts as dust from the excitation system was installed for units 1 and 2 while the these were in a poor condition. Further, mixed with oil from the bearings and turbine governors for units 3 and 4 will corrosion could lead to a complete carried around inside the generator be replaced during year 2003. collapse of the steel lining. Consequently, pit. The combination of carbon dust it was necessary to recondition these Pipeline Insulation for Cooling parts with a new protective layer of Water Pipes paint. The insulation of the cooling water All the steel lined waterways pipes was heavily damaged and created (mainly the 185-meter high vertical huge condensation problems inside shafts) were sandblasted and painted. the powerhouse. The increased air The total painted areas amounted humidity made water drip almost all to approximately 8,000 m 2 . In order over the plant, causing considerable to protect the powerhouse from contamination. exposure to quarts sand and dust, a In order to implement a new huge ventilation system was arranged computerised control and protection to make an under pressure inside the New slipring brushes 5