wet hammermill, or a Brunette BioSizer. The latter was added to handle the mill’s bark intake for the energy system, but was also chosen to give the mill some flexibility, as Sellin explains. “It’s mostly for bark, but Comact set it up so that it can be fed from both sides, and used with smaller screens to pre-grind the chips to bypass the green hammermill if need be, or to deal with fibre quality issues. It gives us a lot of flexibility to keep the plant running no matter what.” After the BioSizer or green hammermill, fibre is sent to the single-pass rotary dryer. Bulk material drying pioneer Thomp-son Dehydrating Company out of Kansas supplied it, along with the cyclones. Process heat is supplied by a 16 MW system from KMW out of London, Ontario, who was on site during our visit, ramping both the energy system and dryer up to full production capacity. From here fibre goes to a dry storage bin, which at six to eight hours is the plant’s only significant surge capacity, as Sellin explains. “After the dry hammermill, it is way too dangerous to build in any surge capacity in my opinion. We looked at it, and I had to battle that one out with a few people who wanted additional surge there, but I didn’t feel comfortable at all with the explosion risk.” In fact, Sellin adds that safety was an overriding design prin-ciple all the way through the process. He had seen far too many dangerous situations in his travels, and was not willing to accept that same hazardous working environment at Trebio. The company approached its insurance partners, Lumbermen’s Underwriting Alliance, and asked them what they would want to see in an ideal pellet mill. The insurers handle the majority of the pellet sector, and so had a good idea of what they wanted. “They basically came up with a wish list for the ideal plant as far as fire and explosion safety goes, and that’s what we did,” Campeau says. “Now it’s their model for other plants.” The plant is protected at all risk areas from the output of the dryer to the end of the process by a Flamex MiniMax spark detec-tion and suppression system, but that is just a start, Sellin notes. “The process and all the presses are controlled by PLCs, so we can proactively manage for changing conditions. There are tem-perature probes in the mills alerting us to any risks. And we’ve added safety measures that also allow us to maintain production at higher levels, safely.” One such touch is a reversing screw at the infeed to the dry bin. Not only does this allow operators to dump out material to the ground below whenever there is possible danger, but it also means they can easily get rid of wet material before it contami-nates the dry bin or disturbs downstream production. “I’m very happy to have done that. Otherwise you end up with a nightmare in the dry bin or in your pellet mills. I’m sure we’ve increased production by 25% just because we handle issues out here.” Trebio has also avoided some explosive situations by keeping much of the dry material handling process outside. The entire process, from fibre intake through drying, the dry bin, and even the Schutte-Buffalo dry hammermill, takes place in Mother Na-ture’s playground. Only at the infeed to the pellet mills does the Our experience makes all the difference We have an experienced team at every stage of a project. We provide design, manufacturing, installation for all your dust collection and air conveying needs. air Filtration pellets plants ProduCts › air pulse › silo › industrial duct › abort gate › screw and belt conveyor ✓ Our prOducts are designed and manufactured tO the highest standards in regards tO market specificatiOns. dust collector › Cyclone › Multicyclone › Fan › rotary air lock › air density separator 1890, 1 st Street, Industrial Center St-Romuald, Quebec G6W 5M6 Tel.: 418 839-0400 Fax: 418 839-0201 www.rodriguemetal.com NOVEMBER/DECEMBER 2011 14 Canadian BIOMASS
Canadian Biomass November/December 2011: Page 14
