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Zawartość zarchiwizowana w dniu 2022-12-27

DIAGONAL FLOW PUMP TURBINE WITH ADJUSTABLE WICKET-GATES AND BLADES

Cel

The NAUSSAC II development project on the upper reaches of the Allier river will make it possible to complete yearly filling of the existing NAUSSAC I reservoir by means of pumping.
The power/pumping station will be equipped with 3 identical Deriaz pump-turbines. The prototype to be demonstrated is a diagonal flow reversible turbo-machine with two means of regulation. It brings the possibilities of Francis pump turbines closer in line with those of variable head and discharge Kaplan pump-turbines (especially in cases where pump discharge is to be adjustable so as to suit river flow at the intake).
This prototype hydro machine will bring about savings on civil works. Such savings will partially match the extra cost of the machine itself for which the period for return on the extra investment will be 8 to 11 years. However, for the full generating set including the prototype, the extra cost is less and can be absorbed in about 5 years.
The overall energy differential is marginal.

1. INNOVATIVE TECHNOLOGY
The prototype is a diagonal flow reversible turbo-machine with wicket gates and adjustable blades which, while maintaining acceptable rates of efficiency, extends the operating ranges for turbine and especially for pump with extremely variable head and/or discharge conditions (there does not seem to be any precedent for machines operating as pumps against such conditions).
The characteristic nominal specific speeds of the prototype are as follows : in pump mode, nq= 8 rpm; in turbine mode, ns 4 = 247 rpm.
2. CONTEXT IN WHICH THE TECHNOLOGY WILL OPERATE
The prototype will be installed in the power/pumping station to be built for the NAUSSAC II scheme, which is the second phase of the development of the existing NAUSSAC I reservoir which maintains required low-water flow in the ALLIER river as well as in the LOIRE river downstream of its confluence with the ALLIER.
The primary purpose of the NAUSSAC II scheme is to pump water into the existing reservoir andthereby make up the current shortfall. An auxiliary function is the generation of energy by turbining release from the reservoir.
The shaft power/pumping station at the dam toe will be equipped with three identical reversible hydroelectric machines. Each will comprise a prototype hydraulic and a conventional motor generator. The prototype runner will be 950 mm in diameter and will turn at 750 rpm.
Each unit will be capable of operation as follows:
- as a pump, under 32 to 57 m head, with discharge of 2 to 5 m3/s; maximum power consumption will be 3000 kW;
- as a turbine, under 32 to 56 m head, with discharge of 1.5 to 5.5 m3/s; maximum power output will be 2650 kW.
The NAUSSAC II development project will also require a weir on the Allier river to create a small pool which will back water up the existing tailrace channel as far as the power station.
3. ECONOMIC ASPECTS OF THE TECHNOLOGY
The parameters of the scheme make conventional Francis pump-turbines unsuitable, for they allowfor only one pump discharge for each delivery height.
To make up for this shortcoming, a Francis pump-turbine could be associated with a multi-speed motor-generator, which would in itself be something of a prototype.
The gross excess cost of the hydraulic prototype with respect to a comparable Francis turbine is 5.6 million French francs. Due to its wider operating range and smaler size, however, the prototype allows savings on the cost of civil works equal to 0.5 million francs yearly instalments over a period of 30 years, assuming an interest rate of 8%.
In fact, however, it is the extra cost of one entire generating/pumping set which should be borne in mind: this is at most only half of the above-mentioned extra-cost, that is to say 2,8 million French francs, and return on the extra investment is achieved in less than 5 years.
Furthermore, the mean annual power consumption (pump) of a 4 GWh and generation (turbine) of 10 GWh results in a balanced overall economic situation.

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SOMIVAL
Wkład UE
Brak danych
Adres
46 BOULEVARD PASTEUR
63001 CLERMONT FERRAND
Francja

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