Instead of the steady hum of steam and woodchips moving through pipes, on Monday, Oct. 14, the biomass plant was a hive of activity.
Power-washers sprayed water onto the machinery, large vacuum tubes crisscrossed the plant, and staffers clad in white protective suits and masks cleaned the gasifier and boiler from a buildup of ash that has occurred over an unprecedented 16 continuous weeks of operation. Heating Plant Operator Myron Selleck was there to see it all, just as he has been for every clean up since the plant’s inception.
“I’ve worked at the biomass plant since it opened and I’ve been at the College for 14 years,” he said. “It’s pretty neat that you guys get to come in here during a maintenance shutdown. It’s one of those things that usually is not glamorous so very few people see it.”
The focus of the heating plant operators’ cleanup efforts was also the main component of the biomass gasification process.
“Inside of this big red box is where we actually gasify the wood chips,” said Selleck of the large structure. “So all of this stuff gets filled up with ash and crud. They’re hydroblasting it with water and big vacuum hoses and people are going in to do some inspections.”
Selleck walked over to the gasifier and points out a pile of what look like football-sized pieces of charcoal.
“Unfortunately, there’s a few chunks,” he said. “What that primarily is is the dirt or any mineral that might be in the wood. Trees come out of the woods so they may have some nails or fencing.”
The size of the charcoal pieces notwithstanding, Selleck says he is not worried.
“Out of 8000 tons of wood, that’s the only bad stuff,” said Selleck. “The rest of it gets taken out with the vacuum truck.”
Despite the apparent scale of the cleanup efforts, Selleck said it should not be surprising given the amount of woodchips they are working with.
“In the last 16 weeks we gasified 8000 tons of woodchips to make steam. Because of the magnitude of the system it takes a little more cleaning than just a bucket and a shovel,” said Selleck.
Making sure that the smokestack above the biomass plant is emitting nothing but water vapor is another goal of the cleanup process.
“The economizer takes all the exhaust gases coming off the boiler and passes through these bins that takes heat out of the exhaust gases and heats up the boiler water,” said Selleck. “They’re cleaning out the economizer with a high-pressure washer and they can run up to six to ten thousand pounds of pressure with their water gun.”
The staffers in the plant are all wearing white protective suits and masks to work with and spray down ash-covered equipment.
“There’s water and there’s ash, so it’s pretty corrosive,” Selleck said. “If it gets on your skin it probably won’t kill you, but it could irritate it.”
A huge tarp had been hung off the edge of the boiler to contain some of the mixture of ash and water that had pooled on the floor in places.
“Before we tried the tarp, the water was everywhere,” Selleck laughed. “Water and the tubes that bring it take the ash and fling it everywhere. We’ve learned over time that the more we can harness that, the less mess we have to clean up.”
Selleck said the plant also has effects beyond the glass façade of the facility.
“Because of our fans, we’re sucking air from wherever we can, and I think we suck every leaf in Addison County up to our doors,” he said. “So inside and outside we’re sweeping up.”
To get up close to the boiler, Selleck pushes aside some caution tape. “Throwing caution to the wind,” he joked. Up at the boiler, the cylinder had been opened up to show the innards of the boiler, and peering inside is like looking into a cave.
Selleck is proud of the work he has done for the biomass plant, and for good reason. He walked around to the oil-burning side of the plant to show what fuels the College when the biomass plant is not running – a pail brimming with thick, black oil.
“They call it Number 6 residual, so it’s not very refined,” said Selleck. “When we burn this, we need to use either compressed air or steam to atomize it and break the droplets up small enough so you can even burn the darn stuff. If you dropped a match in there, it would just go out.”
“It’ll be really nice to get rid of that,” Selleck added.
The job of a plant operator like Selleck requires great vigilance. Pouring over a lengthy checklist, Selleck explains that the biomass plant’s activity has to be monitored almost constantly.
“We’re watching how much oil we’ve burned for the day, we’re watching our temperatures,” he said. “We watch what our kilowatt meter is registering.”
Even while Selleck is speaking, another heating plant operator motions to him to take a look at a printout of some unusual readings for the plant. Scanning the data, Selleck explained that the plant had been using much more water than usual, to the tune of 10,000 more gallons than normal.
“We’ll look at today’s usage tomorrow morning, and if it’s high, we’ll go to the HVAC shop and say, can you guys go out on campus and look for a condensate pump that’s not working? We’re not getting that condensate back,” Selleck said.
Selleck’s verdict on the 16-week-run was unequivocal.
“It’s been spectacular. Certainly we want to try to do that again,” he said.
As for whether they will try to push the limit again, Selleck demures.
“We’ll see,” he said.
Until then, Selleck said the biomass plant will continue to run without stopping for an astonishing amount of time, with little leeway given for its source of fuel.
“Our bunker is only a one-day supply,” he said. “We’re talking about not shutting down again until February, so Christmas Eve, New Year’s Day, we are still going to have three truckloads of chips come in. A truckload of chips lasts 8 to ten hours. We only have a 24-hour cushion in that bunker. It doesn’t stop. There’s someone here 24/7, 365 days a year. We never shut down — even if the trucks stop coming because of a big storm or something.”
Ultimately, the work that Selleck and his colleagues did on Monday and for the rest of the week will make their next run a success as well.
“We’re hoping that by being vigilant custodians and making sure we have a good clean system when we’re done this week, that we’ll get another 16 week run,” he said.