Basic knowledge of small hydro turbine
Author: source: date: 2019-07-30 11:00:47
In many areas, especially in underdeveloped areas, there are indeed problems of small hydropower stations with low investment and poor efficiency affecting the ecological environment.In order to understand the construction structure and working principle of small hydropower stations more clearly in the investigation work, we may first learn what the working principle of regular small hydropower stations is.
1.The parameters of hydropower station
The basic operating parameters of the turbine are water head, flow rate, speed, output and efficiency.
The water head refers to the difference between the water flow energy per unit weight of the inlet section of the turbine and its outlet section, expressed in “H”, and the unit is “m”.
The turbine flow rate refers to the volume of water flowing through the cross section of the turbine per unit time.
Turbine speed is the number of revolutions per minute of the turbine shaft.
The turbine output refers to the power output from the turbine shaft end.
Turbine efficiency is the ratio of turbine output to water outflow.
2.What is a bulb tubular turbine ？
Power plant from influent to effluent direction basically is communicated in axial direction.If the buld turbine hydropower station water inlet outlet pipesare not turning,simple shape,flow channel to reduce the hydraulic loss,convenient construction.
Tubular turbine with high flow ability high specific speed,so in the head and power under the same conditions tubular turbine propeller diameter than about 10%;
Tubular turbine hydropower station has the advantages of compact structure,compared with the same specifications of Kaplan turbine to its relatively small size,can be arranged in the dam,cancel diversion system complex,reduce the workshop building area,reduce the amount of excavation and concrete plant,according to the analys is of revevant data,civil construction cost can save 20%-30%;
Tubular turbine for reversible pump turbine,the flow has no sharp corners,so that the pump and turbine can obtain good hydraclic properties.As for can with bidirectional power,bi-directional pumping and two-way drainage functions six tidal power sation.Therefore,it is suitable for the comprehensive development and utilization of low head water resource;
Tubluar hydropower station in general than the vertical axial flow type hydropower station construction period is short,fast effect.
3.The characteristics and scope of application of Francis turbines
For Francis turbine, the water flow enters the runner from the radial direction and flows out substantially in the axial direction. Francis turbines have a wide range of water heads, simple structure, reliable operation and high efficiency. It is one of the most widely used turbines in modern times. The water head is suitable for a range of 50 to 700 m.
4. The characteristics and scope of application of kaplan turbines
In an axial flow turbine, the water flow in the runner region flows axially, and the water flow changes from radial to axial between the vane and the runner.
The fixed paddle structure is simple, but its efficiency will drop sharply when it deviates from the design condition. It is suitable for power stations with low power and small head change. The general head range is 3~50m.The propeller structure is more complicated. It cooperates with the rotation of the blades and the rotation of the vanes to achieve double adjustment of the vanes and blades, which expands the output range of the high-efficiency zone and has better operational stability.
5.The characteristics and scope of application of Water bucket turbines(Pelton turbine)
It works by impacting the jet from the nozzle against the rotor blade in the tangential direction of the circumference of the runner.The bucket type turbine need a higher water head.
Suitable for high head,small flow and flow changes in large runoff dropower station;
With the power plant investment is small,compact units structure characteristics;
Has the efficiency changes smoothly,opersting a wide range,even in the 15%-20% load is reduced efficiency;
Suitable for high head,small flow station in mountainous area;
A unit constatraction,simple restaction without cavitation condtion,the advantages of stable operation,less investment,constucion area.
6.The characteristics and scope of application of turgo turbines
For a turgo turbine, the jet from the nozzle is at an angle to the plane of the runner (usually 22.5 degrees).This type of turbine is used in small and medium-sized hydropower stations, and the water head is suitable for use below 400m.