FORKS — School staff are already enjoying the benefits of the forced-air heating system installed in preparation for the new biomass boiler system at Forks Middle School.
The forced-air system now operates off a diesel boiler, but it will be used full time once new portions of Forks High School are completed next year.
Pilot program
Quillayute Valley School District’s biomass system — a pilot project for schools in Washington state — will begin heating the Forks Middle School on this year’s coldest days and the Forks High School once the new portions are completed next year.
Nicole Sedgwick said she was accustomed to teaching her middle-schoolers wearing sweaters and jackets.
But the new forced-air system heats the room better than the older steam system, and it keeps out moist air, the seventh- and eighth-grade math teacher said.
“I used to worry about all the colds and that moist air,” Sedgwick said.
“It is already so much better this year.”
Better heating
She said now she can hang her coat up when she arrives at school — even on nonschool days.
The system is now heated using a diesel boiler. Diesel will be kept as a backup system once the biomass system is used in full force.
The biomass system will be used this year if there are more than three straight days of freezing weather — but anything less and it would be inefficient to use the system because it would produce too much heat and make the rooms too hot, said Bill Henderson, who is head of maintenance for the school district.
He said that conditions in the classroom will continue to improve as the biomass begins operating.
The diesel boiler will be available if needed.
“That way, we have something to back us up, no matter what,” Henderson said.
The biomass system cost $1.7 million and was paid for partially by the Quillayute Valley School District and through a $1 million state grant.
Wood chips
The Hurst biomass boiler system, which was put together by Messersmith Manufacturing, is not attempting to generate any energy, Henderson said.
A biomass boiler that produces energy would heat water until it becomes steam. That steam, in turn, can be used to generate electricity.
The process begins with the wood chips.
Right now, during the testing phases, the school district is using debarked hemlock chips, Henderson said.
“Once we know the [emission] standards a little better, we might be able to switch to another kind,” he said.
The district expects to use about 28 green tons of chips every three to four weeks, Henderson said.
A green ton means that the chips haven’t been fully dried out.
Dry air in the storage area helps ready the chips to be burned, he said.
Chips on conveyor belt
Piles of wood chips are loaded into a garage-sized room and a spiral-shaped machine runs along the floor, pulling chips onto a conveyer belt, Henderson said.
The machine moves slowly, almost imperceptibly, and will take up to a week to reach the other end of the pile of wood chips.
Once the chips are on the conveyer belt, they are carried up into a metering machine.
The machine makes sure that the right amount of wood is fed into the fire under the water tank, Henderson said.
The amount could vary, based on how much heat the fire needs to generate.
The chips then are carried into the burner, just below the 2,000-gallon water tank.
There is so much insulation around the fire that the metal on the outside of the burner remains cool to the touch, Henderson said.
The water tank is hotter — the outside reaching close to 100 degrees — but not so much to cause burns.
The water — heated to 180 degrees at most — travels through pipes in the middle school and eventually the high school where air is blown over the heated pipes and warms the classrooms, Henderson said.
Ash captured
The smoke from the burner is released into a funnel-shaped vessel, which forces embers, larger debris and sparks downward into a cylinder to capture the ash.
Yet another pipe draws the smoke upward through the “baghouse,” where 10-foot bag-shaped filters stop more particles from moving upward through the stacks.
“It is a 48-bag baghouse,” Henderson said.
“Only 24 work at a time. There is a meter to see when they get too dirty and then it switches to the other side.”
An automated compressed-air system then cleans the bags with high-pressure air.
“We’re told that these should last us for three or four years before we need to get new bags.”
After being filtered, the air travels up through the 51 ½-foot stacks.
The biomass should easily meet Olympic Region Clean Air Agency requirements, Henderson said.
“There is a school in Montana that has a biomass and it has no emission controls and easily meets state standards — of course, Washington has more strict rules than Montana, but I don’t think we’ll have any trouble,” Henderson said.
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Reporter Paige Dickerson can be reached at 360-417-3535 or at paige.dickerson@peninsuladailynews.com.
