Head works in Hydel power plants

These are structures at the intake of conduits tunnels and flumes. They have booms, trash, sluices for passing debris and gates (or) valves for controlling water flow.

Typical low pressure intake showing headwords for a hydro plant

Booms will divert ice and floating logs from the intake. Trash tracks will remove floating (or) submerged debris directly at the intake entrance. These are placed across the intake structure to keep out floating matter from going through the penstocks.

Rocks will be inform of screen and which consists of parallel bars welded to cross members which are supported by beams. The spaceing between the bars varies from 1.5 to 15cm (or) more. If the spaceing is small the safety debris is increased but it increases the loss of water head.

The head works regarding to low head hydel plants and figure shows the head works regarding to high head hydel plants.

Conduits

A “head race” leads water from the head work to the turbine and “tail race” lead water from the turbine outlet to the down steam side of the plant. These may be carried out with use of any of the following.

a) Open-type flumes b) Closed-type tunnels

c) Canals d) pipe lines

e) Penstocks.

Flumes: These are mainly used when it becomes difficult (or) expensive to construct canals.

A flume is an artificial water channel and which is made of metal concrete (or) steel (or) wood. These are usually of rectangular (or) semi circular shape. The wooden, steel and concrete shapes flumes are as shown in fig

Tunnels: Many times tunnels are very cheaper to convey water from a hilly area to the power house then canal (or) flumes. In hydro power station the tunnels are usually of rock typ. These are generally of circular section (or) horse shoe section and these are as show in fig

The concrete (or) steel lining is usually used for the tunnels to prevent any leakage of water

Canals: The canals are used to convey the water to forebay and these are may be of open (natural) (or) artificial similar to the natural water flow rivers. The artificial canals are constructed with use of concrete lining.