Minimising dust in blown wood-pellet deliveries
Some wood-pellet systems are more sensitive to dust than others, but all systems will benefit from minimising the fines content in the delivered
Dust in air creates an unpleasant and hazardous environment, and is likely to find its way out of the store and into the surrounding area, if measures are not taken to prevent it. Dust in the store will increase the coefficient of friction
and prevent wood pellets from flowing as well as intended. Differential settlement will (if not tackled) lead to build-ups of dust in the store, which will block augers. Dust in the boiler will become entrained in the exhaust air and cause poor emissions and
increased rates of slagging and clinkering.
The techniques for minimising dust are tried-and-tested, but not always applied in an immature wood-pellet market like the Russian Federation. The key techniques are:
- Clean the pellets (by screening
and suction) at each point where the pellets are handled, and particularly at the final point where the pellets are loaded for delivery to the customer.
- Use pressurised tankers to reduce the generation of additional dust during delivery.
low-abrasion pipes (i.e. smooth internal surfaces).
- Minimise the distance and number of angles in the pipes from the truck to the store.
- Use an impact mat (or other device) in a suitable position to minimise damage to the pellets when they
enter the store.
- Use suction systems on the outlet to extract some of the remaining dust and (more significantly) reduce the pressure in the store to minimise the escape of dust into the surrounding area.
These elements are standard
good practice for blown wood-pellet deliveries on the continent, where they have had more experience to refine the techniques. OOO NEFTEPROM is one of only a small number of wood-pellet suppliers who offer this continental-standard of delivery (for points
1, 2, 3, and 6 - points 4 and 5 are the responsibility of the customer and their installer).
Clean wood pellets before a blown delivery
All of our stores and depots are equipped to clean the wood pellets
to less than 1% fines before loading on our trucks. We inspect the pellets during loading. We take samples from every load, so we can test that the cleaning is working to keep the fines below 1%.
Pressurised tankers for
Tippers use gravity and the weight of pellets in the tipped body to push the pellets into the blower pipe. The pellets would naturally flow too fast and block the pipe, so tippers control the flow with a rotary valve. This is
effectively a mincing machine that damages the pellets as they flow through it.
Pressurised tankers use air pressure to push the pellets into the blower pipe. There is no need for a rotary valve. The pellets encounter no moving parts in the process.
Tippers also have dead corners on either side of the body, where the wood pellets would get stuck if they weren't moved mechanically towards the outlet. Typically, tippers include augers running from these corners to the outlet in the centre of the rear
of the body. These augers cause more damage to the wood pellets.
Tippers are not as gentle as tankers, but the extent of the damage depends on the way that the driver operates them. You need skilled, trained operators for both types of truck. An unskilled
driver operating a tanker may do more harm than a skilled driver operating a tipper. However, a skilled driver operating both will get better results with a tanker than a tipper. We only use skilled, trained drivers for our deliveries.