Hitachi, Ltd.

Kazuo Niikura

Ryoji Okada

Keiji Taguchi

Katsumasa Shinmei

Katsumasa Shimmei

Kiyohito Tani

An existing water-lifting pump is converted into a reversible pump-turbine which functions as not only a water-lifting pump, but also a pump-turbine capable of generating electric power. An existing pump runner is modified or replaced with a replacement runner. Movable guide vanes are disposed, or the rotational speed of the runner is increased. Alternatively, water passages in the stationary parts are modified. A pumping station can be given with the function as an urgent power plant in the event of an electric power shortage. A converted pump-turbine having good pump-turbine characteristics can be economically obtained.

Method of converting storage pumps into reversible pump-turbines

A water machinery runner, which is highly reliable and is so excellent in wear and corrosion resistances that it can be used even under conditions where sediment is contained in a fluid includes crown 21, band 22 and blade 23 of a water machinery runner 2 to be rotated by a working fluid or a fluid flowing in a passage. The elements of the machinery runner are coated on at least portions of their individual surfaces with a first surface film containing a metal, as selected from the group consisting of Ni, Cr and Co, and a chromium carbide, and a second surface film containing a metal, as selected from the group consisting of Ni, Cr and Co, and a tungsten carbide.

Runner, water wheel and method of manufacturing the same

A method of starting a variable-speed pump turbine or a variable-speed pump driven by a variable-speed generator motor or a variable-speed motor connected to an electric power line in parallel therewith. The generator motor or the motor is first operated at low speed with the guide vanes or the delivery valve fully closed. The low speed is lower than a stable starting speed of the pump turbine or the motor but high enough to prevent backward flow of water into the pump turbine or the pump. After the operation is set at the low speed, the guide vanes or the delivery valve are opened and the opening degree is gradually opened until the speed is increased to a speed optimum for the steady operating condition of the pump turbine or pump. This method effectively suppresses abrupt increase in the pump input power required for the driving of the pump turbine or the pump, whereby unfavorable effect on the electric power line is avoided advantageously.

Growing community of inventors

Tokyo, Japan

Kazuo Niikura