The Cochwillan GoFlo screen is now fully commissioned and running. Below is a selection of images from the Cochwillan hydro site. The image above shows the travelling water screen in situ with the bulk of the 4 metre long screen submerged by water. The water within the intake channel at this time of year contains a substantial amount of autumnal debris, notably leaves. If this screen was a static screen, the accumulation of leaves would quickly clog up the fine meshed screen and reduce flow to the turbine, subsequently reducing its generating potential and income earned. It would also require ongoing intervention to manually rake away the debris. The GoFlo self-cleaning screen, however, keeps the mesh free from debris and maintains good flow to the turbine, as well as liberating the site owner from tedious screen maintenance tasks. The meshed screen is essentially a rotating belt which lifts debris out of the water.
The images above show what happens to the debris after it has been lifted from the water. At the highest point of the screen, debris is removed from the screen by a spray bar, which blasts a jet of water through the screen mesh. The debris then falls into a trough partially submerged in water. The trough is connected to a sluice which periodically opens enabling the debris filled water to be returned back to the watercourse, downstream of the intake. The mechanism happens automatically and requires no manual intervention. The images also show how the screen motors, which although have a submersible rating, are located well above the calculated flood level of the river.
The self-cleaning screen is located adjacent to the river (Afon Ogwen), just upstream of the weir (above left) and screens water prior to entering the penstock and turbine. Debris laden water is then returned to the river via a pipe (also visible on the image, above left) downstream of the intake. The intake area in which the screen is located within a specially constructed concrete structure in a secured area.
The screened water then flows through the penstock, underneath a dual carriageway, through to the turbine house and the 90 kW Crossflow turbine, seen above.