When considering installing a biomass boiler solution, one of the main objectives is to ensure as much automation as possible and this is particularly the case when it comes to feeding the boiler with the necessary fuel. Because of this, it is important to consider the location of the fuel store in relation to the boiler house or plant room in the early stages of the system design.

With over ten years of experience in the design of biomass boiler installations, to which fuel feed systems and fuel delivery are of integral importance, Rural Energy has developed some pioneering and unique solutions. Using our in-house design experts we have had to approach a multitude of biomass boiler projects that have each required a different type of fuel feed, which we have listed below.

Wood Chip Systems

For stores that contain wood chip, a way of moving the chip onto the conveyance system which feeds it into the boiler is vital to minimise the possibility of ‘bridging’. Bridging occurs because of the inherent non-uniform characteristics of the fuel which can see the individual chips interlocking and causing a build-up in the store, unless the floor has a device installed to prevent this.

1. Spring Agitator: the spring feeder (two rotating spring loaded arms that drag the fuel towards the extract auger) is suitable for small and medium sized fuel stores and where the wood chip fuel is G50 size or below. 
2. Walking or Scraper Floor: the scrapers are a hydraulic ‘walking floor’ system. This is most appropriate in a wood chip fuel store where its capacity is in excess of 150 cubic metres or the wood chip being used has a moisture content approaching 50%.

Wood Pellet Systems

Although most wood chip conveyances can also be used for pellets, the same cannot be advised in reverse as the lighter construction of the pellet augers means they are restricted to this type of fuel only. Therefore if a client plans to change the fuel type as some stage during the installation’s lifetime, or simply wishes to ensure being able to use fuel from different sources, it is vital that the fuel feed is capable of handling wood chips, even if pellets are the initial fuel type used. Rural Energy ensures all these requirements are taken into account at the early design stage, also taking into account the fuel store’s location in comparison to the boiler in order to create a substantial, dependable system.

Fuel Reception Systems:

The fuel reception area is the location where the fuel is unloaded from the delivery vehicle. As a space saving solution, and also for ease of fuel delivery, wood chip stores are often in an underground, well hidden bunker. To make fuel delivery as quick and simple as possible, a delivery of fuel in a vehicle that can simply tip the chips into the storage chamber is a primary consideration. Other design considerations include turning circles and head room for the tipping trailer, so they need adequate space for both, the type of bunker lid (lift or slide) and of course appearance.

As some sites may have constraints or aesthetic demands on all of these factors, Rural Energy and Herz together designed a vertical elevator to meet requirements. These solutions mean that the delivery vehicle can still reverse up to a trough, unload a certain amount of wood chip which is then conveyed via a horizontal auger at the bottom of the trough to a vertical auger, followed by one or more additional screws into the fuel store. A great solution for above ground wood chip fuel stores and still a very speedy delivery is achieved.