Pictured: Ranheat hogger-loader

As we head towards the UK heating season, just how easy is it to make your factory self-sufficient and not reliant on oil or gas as a source of heating? Chris Franklin MD at Ranheat Engineering Ltd – a leading UK manufacturer of wood combustion equipment – continues his series of exclusive articles for Furniture & Joinery Production. This issue he looks at how little waste is needed to replace expensive oil and gas heating systems.

Industrial wood-waste has a high energy value. Man-made boards generally have a low moisture content and thus a high calorific value. A generally accepted “yield” on industrial wood-waste is 3,200kW hours per tonne (this includes a reduction for combustion efficiency). 

Let us consider a small kitchen manufacturer with an industrial unit of 10,000 ft2, for example. If the company produces 2 tonnes per week of off-cuts and extracted dust, this can replace 6,400 kW hours. If we look at a 150-kW warm air system with an average running time of 40 hours at 50% load, this is a requirement of 3,000 kW hours.  At 100% load this is only 6,000 kW hours. So, 2 tonnes per week is more than enough.

Pictured: Traditional Bag dust extraction filter modified and mounted directly onto Ranheat Silo

Even at 2 tonnes per week, some level of automation is required, so a small wood chipper to granulate the off-cuts and extracted material in the form of bags can be introduced into a warm air heater using a Ranheat Bag-loader.

The best solution is to utilise a silo into the system. This increases the cost but does allow the heater to run for extended overnight and weekends. This greatly increases the disposal rate, enabling a 150kW unit to dispose of 5-6 tonnes per week and a 300-kW unit 10-12 tonnes per week.

Existing floor standing “bag filters” can also be converted into a silo mounted filter system.

The bag-loader is a simple metal box with internal agitators and a screw that feeds material into a 150kW Ranheat warm air heater.

A variation on the simple bag-based system is the Ranheat hogger loader. Offcuts are simply tipped into the hopper of the hogger (wood-chipper) and granulated on demand and fed into a warm air heater.

The bag-loader and the hogger loader are for use with warm air heaters and are not designed to be left running overnight or at weekends.

Pictured: Ranheat Bag-Loader

Whichever Ranheat system you go for, or indeed any wood-fired installation using waste wood, will still need to meet all the current regulations.

You are still legally required to obtain planning, chimney height approval and permits to enable you to legally burn wood-waste. This can be in the form of an exemption from the EA for up to 50kgs per hour, or a permit for a SWIP or a full part B permit. Ranheat are on hand to give free assistance with obtaining these permits and permissions.

Ranheat also make spares and service and repair other makes of woodburning boilers and heaters.

For further information on all types and sizes of industrial woodburning equipment from 150 kW upwards, contact Ranheat.

01604 750005