Storage and handling
There are three discreet elements -
Access must be appropriate for delivery vehicle in mind. The tipping or transfer of fuel should be quick and simple to minimise your costs. The proximity to the boiler is a key consideration.
The amount of storage required will depend on the size of the system and the frequency of deliveries. As a rough guide the following gives an indication of the storage volume for chip, that may be required depending on delivery frequency. You should be able to store enough fuel for a least 10 winter days, unless your local delivery is very robust.
1MW at 100% output = 2 lorries a day =100m3 store
Thus:
250kW at a normal 50% cycle = 1-2 deliveries per week = 50-70m3 store
The smooth transfer of fuel from the storage facility to the boiler is critical to efficient running. Larger systems will require an automated feed, commonly using an auger or walking floor. There is also an agitator to prevent bridging and to ensure a constant flow to the boiler.
All three of these must be considered with care, as they all impact on the cost of the installation. If they are designed poorly then the running may be problematic. In some cases lower capital expenditure on fuel storage at the outset has lead to high operating costs throughout the lifetime of the boiler. Having said that, some low cost solutions are available and work very well.
There are various options for storage
Click here for wood storage diagram
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Hook lift bins
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- Suitable for situations where space is limited
- Fuel delivery may be complex
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Covered shed
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Health and safety issues relating to woodchip storage and handling include: mechanical and electrical hazards, e.g. motors and drives, enclosed spaces, e.g. hoppers and silos; and respiratory problems caused by dust and fungal spores.
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Underground bunkers
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- Ideal for large scale installation
- Easy of delivery by tipping vehicle
- Can be expensive to construct
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Hoppers
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- Relatively cheap to install
- Specialised equipment required for efficient delivery
- Delivery by bag and crane is time consuming and adds to fuel costs.
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