Northeast Biomass Heating Expo hosts biomass boiler bus tour
The Northeast Biomass Heating Expo being held in Portland, Maine, April 9-11, kicked off by taking a bus full of tour goers on a trip throughout the region to visit the site of five woody biomass heating installations and a boiler assembly and pellet redistribution facility.
The first stop was Hancock Lumber, which hosts a 9,900 Mbh steam boiler. According to General Manager Shane Hancock, there is an additional boiler on site, a backup oil boiler that “burns 98 gallons per hour at full throttle, and is used very little.”
The biomass boiler, rated at 300 horsepower (hp) can sometimes reach 400 hp, Hancock said. “We’re right on the edge of that right now…depending on the severity of the winter, which influences how much hp we can get out of it.”
Boiler fuel consists mostly of green sawdust, but when its demand is high, a mixed dry fuel is used, including chips and ground up bark, which is more ideal to use in the winter when it is frozen. “We can’t use bark in the summer though, as it becomes stringy,” Hancock said.
The steam is used in six dry kilns to dry lumber, and also heats the entire facility.
The next tour stop, Oxford Hills Comprehensive High School, hosts a 4,300 Mbh wood chip boiler that will burn chips containing up to 50 percent moisture. Bede Wellford, who served as boiler supplier Viessmann’s representative and supported installation and commission of the system, explained the importance of careful design of the tip floor. “The tractor trailers back in as far as they can, and as they unload, the chip piles raise them up…clearance is very important.”
Welford also emphasized the significance of chip quality. “At commissioning, I walked in here and found a bunch of two-foot-long sticks. When I help somebody laying out a project for the first time, the very first question is ‘what’s your fuel?’ If it’s chips, the next question is ‘where is it coming from, and do they understand [the use]?’ Because we don’t have standards for chips in this country, other than the paper industry.”
Following Oxford Hills Comprehensive High School, the bus took its riders to the Oxford County Courthouse, which, in its basement, hosts three 191 Mbh pellet boilers with bag storage. The bags, which rest near the boilers, store about 15 tons of pellets, or enough for one heating season. Pellets are are pneumatically conveyed into the boilers.
The facility still houses an oil boiler for back up, which is tied into the same chimney as the pellet boiler system. “Both can’t run at the same time, “explained Richard Grondin of Integrated Energy Systems, the engineer who designed the pellet boiler heating system. “There’s a thermal lock out that senses flu gas temperatures and won’t allow a [system] switch until the other system cools down.”
On tips to others thinking of installing similar systems, Grondin said making sure everything can fit inside of an existing building will save a lot of money.
Following the courthouse, attendees had lunch at Maine Energy Systems and were able to tour its boiler assembly warehouse, and then stopped to examine Rowe Elementary School’s 500 Mbh pellet boiler with outdoor silo storage.
The tour concluded at Falmouth Middle and High Schools, which are heated via a 6,800 Mbh wood chip boiler plant and a 3,500 Mbh wood chip boiler plant, both of which utilize Messersmith boilers. The two systems heat the middle and high schools, as well as an elementary school, via underground distribution.