Composition: water diversion parts, water diversion parts, working parts, water discharge parts
1. Water diversion parts
Composition: water diversion chamber (volute), seat ring
Function: Introduce the water flow into the water guide part evenly and symmetrically with a small hydraulic loss, and form a certain amount of circulation before entering the guide vane.
2. Water guide parts
Composition: guide vane and its operating mechanism, top cover, bottom ring
Function: adjust the flow into the runner and form the required amount of the runner
3. Working parts
Function: Directly convert water flow energy into rotating mechanical energy
4. Drain parts
Composition: drain cone, draft tube
Function: To guide the water flow into the downstream, and the draft tube also forms a vacuum after the runner. The potential energy between the runner outlet and the downstream tailwater is used to restore part of the kinetic energy loss at the runner outlet to improve efficiency.
Water turbines are mainly used for pumped storage power stations. When the power system load is lower than the basic load, it can be used as a water pump, using excess generating capacity to pump water from the downstream reservoir to the upstream reservoir to store energy in the form of potential energy; when the system load is higher than the basic load, it can be used as a water turbine, To generate electricity to regulate peak load. Therefore, the pure pumped storage power station can not increase the power of the power system, but it can improve the economic operation of the thermal power generating unit and increase the overall efficiency of the power system. Since the 1950s, pumped storage units have received widespread attention and rapid development in countries around the world.
The pumped storage units developed in the early days or with high heads mostly adopt a three-machine type, which is composed of a generator motor, a water turbine, and a water pump connected in series. Its advantages are that the turbine and the pump are designed separately, which can have higher efficiency, and the unit rotates in the same direction during power generation and pumping, and can be quickly converted from power generation to pumping, or from pumping to power generation. At the same time, the turbine can be used to start the unit. Its shortcomings are high cost and large investment in a power station.
The blades of the runner of the diagonal flow pump can rotate, and it still has good operating performance when the head and load change, but due to the limitations of hydraulic characteristics and material strength, by the early 1980s, its highest head was only 136.2 meters ( Japan's Takane First Power Station). For higher heads, Francis pump turbines are required.
The pumped-storage power station is equipped with upper and lower reservoirs. Under the condition of storing the same energy, increasing the head can reduce the storage capacity, increase the speed of the unit, and reduce the project cost. As a result, high-head storage power plants over 300 meters are developing rapidly. The Francis pump-turbine with the highest head in the world is installed in the Bainabashta power station in Yugoslavia. Its stand-alone power is 315 MW, the turbine head is 600.3 meters; the pump head is 623.1 meters, and the speed is 428.6 rpm, in 1977. Put into operation every year. Since the 20th century, hydropower units have been developing towards high parameters and large capacity. With the increase of thermal power capacity and the development of nuclear power in the power system, in order to solve the problem of reasonable peak shaving, in addition to vigorously developing or expanding large-scale power plants in major water systems, pumping storage power stations are actively being built, and pump and turbines have been rapidly developed.
In order to make full use of various hydraulic resources, tidal waves, plain rivers with very low heads, and even waves have also attracted widespread attention, thereby enabling the rapid development of tubular turbines and other small units.