Wood Pellet Store Optimisation

Getting the best out of your wood pellet store

Storing wood pellets in the correct way will help to preserve the quality of your biomass fuel, which in turn could help improve your boiler’s efficiency. Here’s our tips on how to optimise the storage and delivery of your wood pellets for warm and stress-free heating.

Wood Pellet Storage

Wood pellets can be stored in a variety of ways depending on the requirements and restrictions of the site but here are some good general guidelines to follow:

  • Ensure your pellet store is not ventilated as wood pellets can absorb air humidity
  • Check that you have external access to your store, including practical means for removing the biomass fuel
  • Make sure you have a safe and practicable way of pouring bagged pellets in the store, even if the store is designed for bulk delivery
  • We recommend your pellet store is on the ground floor with easy vehicle access

Bulk Pellet Delivery

When receiving bulk wood pellet deliveries, there are some general rules that are worth considering:

  • Install an impact protection mat to reduce the degradation of the pellets during delivery
  • Fit Storz 110A inlet and exhaust points with caps in your fuel store
  • Good practice is for the inlet and exhaust to be no higher than 1.5m unless you install a secure platform
  • Bends in the pipe work should be minimal and it’s recommended that they have at least 500mm radius
  • Installation of vertical pipes should be minimised; due to the greater delivery pressure required, which causes degradation of the pellets

Fuel Store Sizing

Ensuring your hopper is both the right size for the volume of wood pellet you require for storage, and to feed the boiler is very important. A small fuel store will result in you paying a higher price for more frequent deliveries of smaller loads.

Your wood fuel store should be large enough to ensure enough fuel is available to accommodate your heat demand between deliveries and designed in a way that maximises the space available for full load deliveries. The fuel store should be sized by 30-40% larger than the effective volume needed to allow for unusable areas and ‘dead space’.

A badly designed fuel store, fuel extraction or boiler feed system can result in pellets bridging and excessive dust accumulation that will restrict the flow of wood fuel into the fuel feed system, and therefore reduce the wood fuel automatically fed to the boiler.

Blown Pellet Delivery

Wood pellets are blown from the delivery lorry through in-feed pipes into the fuel store at high speed. Pellets can become degraded when they impact on obstructions such as multiple bends or blockages in the in-feed pipes, causing subsequent storage and boiler performance problems.

  • If bends in the pipe are necessary, then a ‘long radius’ of no less than 300mm but ideally around 500mm, with a length of at least 500mm between bends, should be considered
  • The length of hose should ideally be kept to under 15 metres. The longer the hose run the longer it will take to discharge and the greater the risk of the pellets disintegrating
  • Similarly, the hose should be laid straight from the lorry to the hopper or at least with a limited number of sharp changes of direction for the same reasons above.
  • To help prevent pellet degradation on delivery, a rubber impact protection mat made of a suitable material such as High-Density Polyethylene (HDPE), of 1mm thickness or greater, and approximately 1.5m x 1.5m, should be installed in the impact area to provide additional protection for the pellets

Unsuitable seals in the partition between the pellet store and boiler room can cause high levels of dust emissions to enter the boiler room and settle on motors and gearboxes. This presents a risk of explosion, as well as increasing cleaning maintenance.

Good housekeeping is essential to ensure that dust is cleaned regularly from the surfaces in a boiler room to prevent a source of ignition and risk of explosion.

Maintenance and Emergency Access

  • Observation windows at various heights should be built into the fuel store at positions easily viewable. Alternatively, level sensors can be used in conjunction with automated messages for fuel ordering prior to the store being empty, ensuring you never run out to fuel
  • An access hatch into the fuel store is required for emergencies and should include a window. Access hatches should be positioned in easily accessible areas and should only be used by trained maintenance engineers that are certified to work in confined spaces
  • A double seal door is required to prevent dust from escaping. To avoid health and safety risks, doors should open outwards and an internal barrier should be incorporated for holding back the fuel when the door is opened. This could take the form of slatted wooden boards that slot into metal runners in front of the door
  • Fuel stores should incorporate a door for emergency use only, and should not be used on a regular basis

It is recommended that fuel stores are completely emptied once a year and any dust build up removed with a vacuum. As fuel stores are hazardous places posing a variety of risks, AMP Clean Energy recommends that fuel stores are professionally cleaned, and of course we have our own team of trained specialists in this area.

Delivery Access

When looking at your biomass installation, how you receive delivery of your wood pellets should be a top consideration.

  • Delivery lorries need to have safe access to sites and ideally be able to park within 10m of the wood fuel store to connect the in-feed hoses to deliver pellets directly into the fuel store
  • Wood pellet delivery connections should be located in a position that is easily accessible and at a safe height whilst standing

AMP Clean Energy has a range of ENplus delivery vehicles in varying sizes from 4 wheeled silos to 8 wheeled tipper tankers which means we can deliver to most properties. If you are unsure please call us on 0800 157 7331 and our customer service team will be happy to help.

Delivery Couplings

There are numerous means of attaching the delivery hoses to fuel hoppers, though the industry is beginning to standardize and settle on the Storz 110A type coupling, which have an identical locking head with no separate male or female halves, and are available with BSP male and female threads, or serrated hose tails for fitting into rubber hose.

Blank caps are available for shutting off delivery when not in use. The maximum working pressure for this range of couplings is 16 Bar and they can be produced aluminium alloy and brass or stainless steel.

The Storz Coupling locking head possesses 2 lugs. Any combination of female, male, hose tail or blanking cap can be secured together with the same lug dimension.

Expert help at your fingertips

Our expert consultancy team has helped many customers to reap the wider benefits of a fully optimised installation. We can help with both the design and optimisation of your fuel store so please do get in touch to discuss how we can help you.