“For contaminated wood, a grinder can use hardfaced teeth designed for abrasive materials. A chipper can rapidly lose ef-ficiency as knives lose their edges, but a grinder is designed to operate with blunt teeth. So grit and gravel doesn’t affect the grinder as much as it does a chipper,” Brick says. “A chipper works best with straight logs versus logs with lots of branches and limbs. Grinders tend to handle irregular pieces more efficiently.” Grinders are good choices for producing woody biomass where the customer speci-fications have more room to vary. “If they’re just looking for more of a boiler fuel, they don’t care as much about the size specs that they’re looking for. A grinder would be a better choice,” Spread-bury says. “A grinder is much more diverse. You can put all kinds of different things in there. And by changing the tooling, you can radically change the end product that you’re getting out of the machine.” For producing residential wood pellets, the feedstock needs to be relatively clean, and a chipper is likely the better option for processing the wood due to its ability pro-cess clean feedstock quickly. “If you’re going into industrial pellets that can be a little dirtier, so you can get into some grinder type applications,” Brick CB_WIF_WINTER23_JLR.indd 1 2023-02-06 says. That said, there are biomass-fuelled power plants that require clean wood chips and microchips for specific specifications. If you’re burning wood chips in a power plant that was converted from coal, wood chips have a tendency to flow better in the feeding bins than grindings. “With a lot of your traditional coal-pow-ered plants, the angles of the hoppers are designed for coal, so when you start throwing wood waste in it, chips often flow better than the shredded texture from a wood grinder. The ground material has a higher tendency to bridge up, where chips are generally more of a defined length – no frayed edges on them – so they flow better NFPA68 ◆ NFPA69 ◆ NFPA77 ◆ NFPA91 ◆ NFPA499 ◆ NFPA654 ◆ NFPA664 through conventional power plants than a Allied brings 48 years experience to help you meet current NFPA Standards ground wood product,” Brick explains. with: system design/documentation, spark detection, isolation, grounding, He adds that with power plants set up PLC, venting, blast path management, clean-up systems and duct audits — to use “true biomass” it’s generally not as CWB certified and member SMACNA. big of a deal to use dirtier feedstock. One Sawmill – Biomass – Boardplants – Pulp & Paper – Power Generation – Mining big advantage with these plants is that you 48 years of Industrial Air Systems can get a broader source of feedstock from www.alliedblower.com ◆ Phone: 800-576-3611 grinders. Surrey,BC ◆ Vernon,BC ◆ WilliamsLake,BC ◆ Edmonton,Alberta ◆ PrinceAlbert,Sask “The tops of the trees have no value ◆ Mobile, Alabama ◆ for making wood or paper, so you gener-3:38 PM Combustible Dust Specialists Canadian BIOMASS 17
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