Project Overview

To replace an existing intake which suffered from severe blocking problems.

  1. Increase generation of scheme by improving intake screening performance.
  2. Reduce operational costs related to screen cleaning and supervision.

The Doorian scheme was built in 2001 but the intake structure utilised a side-intake, upstream of a small weir. Located on boggy peat moorland, the intake blocked very quickly with grass on a regular basis, leading to significant lost generation. Having provided operation and maintenance services at the site since 2007, Dulas were contracted by Celtic Hydro to design a new intake structure to enable the installation of Coanda screens and increase plant generation.

Dulas delivered a turnkey project including all consents, landowner negotiation, construction, project management and optimisation. The project was completed on time and within budget.

Solution

In order to maintain pipe inlet submergence, “quarter height” high capacity Coanda screens were used. This resulted in a low weir structure spanning the river with a new fish pass and ‘splash-trough’ on the downstream side of the weir. Construction required the diversion of the river and negotiation with an adjacent landowner to facilitate this.

Since commissioning, the generation of the scheme has increased by 79% (calculated by correlation with a scheme with an adjacent catchment and similar operational profile). The scheme is in the Republic of Ireland, with relatively low tariffs, in spite of which the work will payback in a little over three years.

Key Features

Power Output

 310kW

Intake

 High capacity Coanda Screens

Pipeline

 Hepworth 450mm dia
Turbine Canyon Twin Jet Pelton
Generator Synchronous
Gross Head 110 m
Design flow 400 l/s