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Cheltenham, Gloucestershire, United Kingdom, 2014/05/06 - Spirax Sarco and the team at Dallol Energy combined to provide the boiler controls and steam system for an innovative energy scheme - Dallol.co.uk / SpiraxSarco.com.
The project uses a wet biomass boiler system to heat around 200 Scottish homes via a district heating system and to deliver steam to a neighbouring distillery. The plant is owned and operated by Ignis Wick, which is a subsidiary of Ignis Biomass.
Following a procurement process, Ignis Wick took over the district heating scheme in Wick, Caithness, in 2012 from the Highland Council after the project experienced a variety of technical and commercial problems. With most of the old equipment stripped out of the energy centre building, the company engaged biomass steam specialist Dallol Energy (formerly the team at KIV UK) to deliver a 3.5 MW boiler and plant steam distribution system that would use locally sourced clean woodchips as the fuel.
“For this project we needed a reputable partner that could help us design, commission and install a whole new boiler house and steam distribution system,” says Victor Buchanan, Director at Dallol Energy. “We knew we could trust Spirax Sarco’s knowledge and proven technology and they were happy to trust our biomass expertise.”
The biomass boiler generates steam at 20 bar g. The plant steam system reduces the pressure of the steam to 10 bar g before sending some of it to the neighbouring Pulteney Distillery, whilst the rest is passed through a steam to water heat exchanger that generates hot water for district heating. A steam accumulator vessel acts as a buffer between the biomass boiler and the rest of the steam circuit, which makes it easier for the system to cope with steam demand variations and helps to maximise the productivity of the system. There are also two backup oil-fired boilers on standby for times when the biomass boiler is undergoing maintenance.
Spirax Sarco provided all the steam distribution equipment, including the heat exchanger skids and the boiler house controls on the project, as well as the boiler hot well and steam accumulator. The boiler house is equipped with the latest supervisory control and monitoring system and level controls, as well as automated heat recovery blowdown systems to minimise energy losses. The installation was commissioned and project managed under the supervision of Spirax Sarco and Dallol Energy, with Quality Assurance provided as part of the package.
Typically, the main disadvantage of a wet biomass boiler to raise steam over its gas-fired counterpart, is the longer ramp up period required from start-up to being able to deliver process steam. However, the innovative use of the steam accumulator specified by Ignis Wick for this application has completely eliminated any lag time, allowing the plant to deliver steam as and when it is required.
“This application can completely change the way that wet biomass steam systems are used in the future,” says Victor Buchannan. “Any distillery, food factory or commercial steam user that is run on fossil fuel can benefit from a massive reduction in energy costs, made even more attractive by the government in the shape of the Renewable Heat Incentive (RHI). Supply chain sustainability is also a big plus and there is certainly a marketing advantage to run off local forestry rather than gas or oil from goodness knows where! ”
The long term cost of running the system on wet biomass fuel is significantly lower than dried biomass, since prior drying of the fuel is not required. In addition, a wider market of fuel supply is available, including wood fuel that can be sustainably sourced from local forestry suppliers, with prices that should follow the local wood market instead of international energy markets.
This was the first such project undertaken by Ignis Wick, and Spirax Sarco engineers were on hand throughout the installation and commissioning process to help ensure a smooth start up. “It’s taken a bit of sorting out to get the system set up exactly how we want it, but both companies have been responsive and helpful throughout,” says Ignis Wick Director John Chappell.
Ignis Wick has since signed up for an ongoing service and support contract, as well as buying its spares inventory from Spirax Sarco. “This is the first renewable energy project in our pipeline of projects that we are developing and it won’t be the last. We’d certainly consider using both Dallol Energy and Spirax Sarco again where it’s appropriate in these future projects,” John Chappell concludes.
For more information on Dallol Energy: E: victor.buchanan[.]dallol.co.uk