The data logging systems offer key data trends showing how well the boilers are performing. Some examples of these are shown below, and the Case Studies also highlight issues, trends, and remedial actions.
Film showing delivery of wood chip fuel and some of the issues at a French Pilot Project Site
Optiwood case studies
Case study 1 – Large NHS Hospital
The large biomass boiler system at this hospital had a poor track record for its first 5 years, with frequent break-downs, low efficiencies, and a lack of coordination by the Operators and owners.
The boiler system was originally 1200kW with a substantial buffer tank and designed to contribute 20% of the annual load of the hospital. In reality, it never achieved this.
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In 2016, SEWF were asked to review the boiler system and seek to gain accreditation under the Renewable Heat Incentive (RHI). This was achieved in September 2017. The boiler was de-rated to 990kW, a new heat meter system installed and the wood fuel quality improved.
Under Optiwood, the performance of the biomass system has steadily improved, with efficiencies getting close to 80% – excellent for a manually cleaned boiler that has to shut down every weekend.
Improved training of the Operator team has helped significantly, as has a clear and motivated servicing regime. Recent changes to the frequency of boiler cleaning and ash bin faults are likely to increase overall efficiencies by a further 2-4%.
Optiwood training for Hospital Operators and Managers.
Case study 2 – Academy secondary school
This 450kW boiler system, heating a school and swimming pool, has been on a steady improving curve since 2016, due to a motivated Operator and Senior Manager.
The school uses twin ‘hook bin’ mobile fuel silos, with fuel provided by SEWF under a rapid turnaround via local suppliers. The overall efficiencies have steadily improved to around 80% and the boiler provides significant income to the school under the RHI.
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Under Optiwood, the Operator is being used as a mentor to other Operators in the project.
Some areas of improvement in the wood fuel auger deliveries are being implemented, which are likely to increase efficiencies by a few percent.
Case study 3 – Plant greenhouse and Retail company
This 995kW biomass boiler system has a number of design and technical problems.
While the overall efficiencies are around 70-72%, the boiler ‘cycles ‘ frequently and does not have a sustained run time.
The buffer tank provides no holding capacity and is located outside leading to high standing losses.
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Simple delay switches are planned to be added to allow the boiler to operate for longer periods.