Chris Franklin, managing director at Ranheat Engineering, one of the UK’s leading manufacturers of industrial wood-waste burning equipment. Continues his series of articles exclusively for Furniture and Joinery production. This month he looks at running costs for wood burning equipment – in particular collecting the wood-waste – as cost-effectively as possible.

Energy costs have being thrust to the forefront of design, so how can we reduce running costs within the wood-working industry? In simple terms, use less energy and pay less.

In most modern woodworking factories the largest single electric motor is the dust extraction main extract fan. This draws the wood-waste to a central filter and separates the air from the wood-waste. This fan or in some cases fan sets can be 60-100kW.

The traditional way was then to blow from the filter with a transfer fan to a silo, or a box-cart. Often this fan was 14-18 kW and ran the entire time the factory operated. That’s a lot of electrical consumption!

Transfer fans are sized to cope with the large volume of wood-waste that occurs when the filter system cleans. Some filters have continuous cleaning, cleaning a portion of the dust extraction filters on a rotor system. Less well-designed extraction systems do not have this feature.

Cleaning occurs when the main extract fan switches off at the end of a work period. At this time any fine waste held in suspension drops and could overload a less powerful transfer fan. So the transfer fan overloads if not big enough. 95% of it’s running time per day the fan is too big and wasting electricity.

So, what are the alternatives?   

One answer is to mount the filter unit directly on the storage silo as shown in the photograph above. The extracted wood-waste falls directly into the storage silo. No expensive to run transfer fan. So how is this achieved? Simple the silo must be strong enough and designed to withstand the weight and the pressure. Ranheat do not make dust extraction systems, but they make silos strong enough to have most makes of dust extraction filter, mounted directly onto the roof of the silo. Not only is this energy saving but also space saving.

So, what if my filter system is too big to fit on the silo?

Consider using a drag-link conveyor. Typically, a drag-link conveyor uses 2.2 -3kW as opposed to 15-18kW.

Using your own wood-waste to heat your factory has never made more sense but in the design of the system it has never been more important to reduce the cost of getting the wood fuel to the combustion equipment.

Ranheat design, manufacture and instal a wide range of industrial silo’s and non- pneumatic transfer systems as low running cost options.

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