Cromford Mills in Derbyshire is a Grade I listed cotton mill, famous for establishing the first water-power factory system in 1771. The Arkwright Society commissioned a new turbine and waterwheel to be installed in 2023, to exploit the power available at the historic wheel pit, where Bonsall Brook cascades over a fall of 6.5m.
The highly constrained layout within such an important heritage site, plus the EA requirement for 6mm screening, posed a number of challenges. Feasibility and design stages for this work was subcontracted to Derwent Hydro Developments Ltd., with DHPL providing project management, procurement, supply, installation and commissioning activities.
The choice of a 1950s spiral-case Gilkes Francis turbine, refurbished and installed by DHPL, allowed the turbine and generator to be almost entirely hidden below ground, with only the draft tube visible within the wheel pit.
To avoid a mechanical screen-cleaner, an over-wash intake was implemented as an effective, low maintenance 6mm screen, but sacrificing 0.4m of head. The system also includes a water-sourced heat pump system, supplied by Vaillant, with 2 vertical heat-exchangers in the corner of the wheel pit, fed from the turbine forebay tank.
The turbine is capable of 14.5kW, with all the power absorbed into the network of the Mill, and the 38kW of heat will be used within an adjacent building, where a new cafe is planned.
To demonstrate the original technology on which Cromford Mill was founded, a 5m diameter waterwheel was installed on the opposite side of the wheelpit.
Rotating at a majestic 8 revs/min, the overshot wheel can produce up to 1.5kW via a gearbox, belt-drive and DC generator. The wheel layout is unusual because the shaft is overhung from a pair of bearings on the same side of the wheel, rather than a bearing on opposite sides.
The turbine and waterwheel are controlled by a single DHPL control panel. This system manages the interdependent water level and power conditions of the two generators and wider water system. The controller also offers remote connectivity and web-logging facilities.
This website is operated by Derwent Hydroelectric Power Ltd a company registered in England under company registration number 2227448 and whose registered office is situated at Sir Richard Arkwright’s Masson Mills, 41 Derby Road, Matlock Bath, Derbyshire, England, DE4 3PY. and whose VAT number is 507741254.
© Derwent Hydroelectric Power Ltd