The Impulse type turbines are the best election for high head and small discharge hydraulic power resources. They have a compact structure, small size, satisfying performance and high efficiency and need fewer investments. They have been divided into Pelton and Turgo types.
Pelton model name: CJ; Turgo model name: XJ
The diameter of the runner: 0.8m-6m;
Suitable water head: H =80m- 1600m;
Suitable flow: Q =0.1m3/s- 20m3/s;
Capacity of the generator unit: 100kw -80MW.
Theirs shaft arrangements are either vertical or horizontal and they may have single nozzle, twin or multi-nozzles with characteristics such as high head, big capacity, multi-nozzle and good structure, etc.
Composition of Impulse turbine (Nozzle, runner, support parts and deflector parts)
Major components: rotating parts (runner, main shaft etc), nozzle parts (nozzle and related control), seat parts(seat, cover, spiral casing etc), pipeline parts (distributing pipe, brake piping, expansion joint etc), bearing parts and others. Core part is the runner and nozzle for structure.
Structure of Impulse turbine (Runner, spray pipe, baffles plate, spiral casing, tail water tank.)
Component: turbine disc, bucket (uniformly distributed along turbine disc).
Connection type: bolt, integrally cast, weld.
Component: nozzle, nozzle body, needle valve, spray beam, operating mechanism. Needle valve: control the water flow of turbine showed as stroke.
Slowly close the needle valve and reduce the water hammer pressure to deviated water flow out from water scoop and avoid the speed increase.
Guide the water drainage from the scoop into the tail water tank. Generally the spiral casing is steel casting.
Water diversion plate
Prevent the water flow to splash into the above along the runner that cause additional losses.
Installation Model of Impulse turbine
1. In order to improve the speed and flow, two or more nozzles are regularly installed on one runner. Sometimes the two (or more) runners are installed in one main shaft to improve the single output of the unit.
2. Large and medium-sized Impulse turbines usually use a vertical layout, which can reduce the area of the powerhouse and is also convenient to installed multi-nozzle.
3. Small and medium-sized Impulse turbine usually adopts horizontal arrangement, which can simplify the structure, lower cost with convenient installation and maintenance.