Die reuse kragstasie het sowat 16 jaar geneem om te voltooi. Dis vanuit die ou regering en sogenaamde ‘apartheid era” begin en meestal netso oorgedra, 100% werkend 1994. Om krag te voorsien moes die wat daar gewerk het, weet wat gedoen moet word. Dis nie so ‘n ou stasie as die nodige onderhoud wel gedoen was en heel gemoderniseer . Hoe moeilik is dit as mense wel opgelei is om hul werk te doen.
Die vraag is, indien daar soveel gapings, tyd en energie is om te steel, wanneer word daar dan gewerk en onder wie se toesig? Waar is die behoorlike sekuriteit? Maar om soveel van ons belastingbetalers te steel is eenvoudig onaanvaarbaar en die president, betrokke ministers, Eskom bestuur en toesighouers wat hiervoor verantwoordelik is, moet pa staan vir al hierdie diefstal en sabotasie. Dis nie net van gister af wat Eskom gesaboteer word nie.
The modern stations have enabled Eskom to put older, less efficient stations into mothballs, or to start life extension programmes which will delay the need for new power stations into the next century. Tutuka’s first 600 MW generating set was taken into commercial service in May 1985. The sixth and final set of this 3 600 MW plant was brought into service in June. At one stage during construction more than 7 000 people were employed on site.
Tutuka has a number of unique technical features. It was the first station to use a dry ashing technique which will save millions of litres of water when the station is in full production. At the time that this ashing system was built it was the largest of its kind worldwide.
Tutuka is the Zulu word for progress.
The construction of Tutuka began in October 1980. The first unit was commissioned in March 1985 and the power station was fully commercial by June 1991.
Tutuka is situated 25 km from Standerton in Mpumalanga, was the first power station to feed energy into Eskom’s 765 kV extra high voltage system. The coal-fired, six boiler/turbine unit giant contributes 3 600 MW supplied to consumers and industries throughout the country. Electricity is distributed via the substation Alpha where the voltage is stepped up to 765 kV.
Substation Alpha links Tutuka’s 3 600 MV via short transmnission lines with the 765 kV grid. Tutuka was completed on 3 June 1996. Tutuka was the first power station to feed energy into Eskom’s new 767 kV extra-high-voltage system. The 765 k power lines were strung from 45 metre-high pylons spaced along an 80 metre servitude.
Conveyor belts transport the coal from the stockyard via silos to the boiler bunker into the furnace where it burns at a temperature of approximately 1 500ºC. Dust and ash are produced as a result of combustion in a ratio of 10.1. The ash falls to the bottom of the boiler and into a submerged scraper conveyor trough where the dust is separated from the flue gases in electrostatic precipitators, cleaner flue gasses pass through the chimney into the atmosphere 275m above ground level.
Heat produced by burning coal is absorbed by the boiler feed-water in the 500 km of tubing that forms the boiler walls. The water is converted to steam at high temperature and pressure is passed through super heaters to the high-pressure turbines.
Spent steam is condensed and pumped via feed-heaters and de-aerator to boiler feed-pumps and then back to the boiler to repeat cycle. The condenser contains more than 22 500 tubes. The cooling water is itself sprayed into the lower levels of a cooling tower where evaporation removes the unwanted heat from it. The up-draught in the cooling tower is due entirely to convection.
Coupled to the shaft of the four in-line turbines is the generator rotor, which is a cylindrical electro magnet, enclosed in a gas-tight housing. The electricity passes from the generator stator windings to a transformer, which raises the voltage from 22 kV to the national voltage of 400 kV. The electricity is distributed via substation Alpha, where the voltage is stepped up to 765 kV.
Substation Alpha links the 3 600 MW Tutuka power station via short 400 kV transmission lines with the 765 kV transmission grid. The 400/765 kV transformers are each rated at 2 000 MVA and the 765 kV reactors are each rated at 400 MVA. The 400 kV switchyard is of conventional outdoor construction utilizing strung conductors and having a load current capacity of 3 150 A and a short circuit current level of 50kA.
Each of Tutuka’s six boiler-turbine sets is run as a separate entity with its own controls and instrumentation incorporated in its own control desk and panels. There are three control rooms, each serving a pair of sets. Operators monitor and control the computerized functions associated with start-up normal operation, shut-down and emergency operation. The operators are in permanent contact via the station control room with other Eskom control centres that make up the integrated transmission network. Data-logging computers continuously monitor the main operating and alarm systems and provide a constant flow of information on video screens and printers.
Coal crushed smaller than 25 mm is delivered by belt conveyor from the New Denmark Colliery and stored in the local stockyard. The coal is conveyed to the storage areas and recovered by one of three stacker re-claimers, or is fed directly to the power station. Total storage capacity of the stockyard is 3 million tons and coal can be transferred to the power station at rates of up to 2 500 tons per hour. At the power station, coal is stored in six 4 500 ton capacity silos, each of which can serve two boilers. From the silos, belt conveyors transfer the coal to 675 ton capacity boiler bunkers, of which there are six per boiler giving an effective storage capacity at the boilers of 12 hours’ operation at full load.
When a furnace is started up, fuel oil is used until the combustion of the pulverized coal is stable. A Tutuka four storage tanks with a combined capacity of 4 800 tons are used for fuel oil.
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New Denmark Colliery
The Colliery at New Denmark was started in 1980 and when in full production will be one of the largest underground mines worldwide dedicated to a single power station. It is designed to produce a total of 10.05 million tons of coal per annum at full output from two separate mines, and to do this on a continuous basis for 40 years.
One of the deepest coalmines in South African at 200 m, the colliery will mine a single seam averaging 2 in thickness. Coal recovery is totally mechanized with continuous miners and long-wall operations. Underground transport of men and materials will be a rail system. Belt conveyors are used to transport and coal, and the shaft conveyors have the biggest drives for this application in the country, each having 4 x 600 kW units.
In each of the two mine shafts there are automatic winders, which can lift 60 tons or 300 men at a time. From silos at the surface, overland belt conveyors carry the coal 3.5 km from the Central Mine and 6.5 km from the North Mine to the rushing station close to the coal stockyard.
Power Giant Opened
The completed R4 billion Tutuka power tation near Standerton was officially opened by the Minister of Mineral and Energy Affairs Dr Dawie de Villiers. De Villiers De Villiers said Tutuka symbolises the challenges lying ahead in development appropriate energy strategies for a future South Africa. Indeed for that matter for southern Africa.
Tutuka is the third of Eskom’s news generating stations which were planned during the late seventies when growth in electricity sales was at an extreme high point. Growth in electricity sales has fallen during recent months and Eskom has excess generating capacity.