BIOMASS BOILER
INDUSTRY NEWS
Wood chip conveyor.
technology for our operations now and in the foreseeable future.”
Due to the tight location, the boiler was erected in a unique way. A corner stair support was eliminated for erectors to bring in the boiler bottom last after other modules had been lifted into place.
permitted us to erect a boiler quickly and save money in the process”.
To add to the challenges, US environmental regulations were being rewritten when Macon’s power boiler was being designed. Different drafts of standards for the Boiler MACT (Maximum Achievable Control Technology) had been sent out for comment by the government, but the final version had not been released. “Waiting for the final MACT standards was not a good option for us,” said McGahee. “So, we worked with Andritz to design- in the flexibility to meet low numbers for mercury, CO, NOx, particulate size or whatever.”
Best technology Graphic Packaging’s first biomass boiler (stoker-fired) was installed in 1980. “Today, the
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bubbling fluidized bed is the best technology for our low-Btu, high- moisture fuel,” stated McGahee. “We purchased the best
The fuel is wood residuals that would normally have been left in the forest. The boiler system also has the capability to combust up to 7.5 t/h of clarifier sludge from the paper mill. Natural gas is used as the start-up fuel. About 23% of the total biomass used at the mill comes from in-house wood processing for the pulp mill. The rest is procured in the open market. In total, the two power boilers consume about 120 t/h of biomass.
The Andritz boiler passed its hydrostatic test the very first time. Only five steam blows were required to clean the steam
piping to the turbine. “This proves that the fabrication of the boiler in Europe and the storage/ transport was well-managed,” said McGahee, “and that the erectors kept everything very clean with excellent quality control”. Boiler start-up was in August, 2013. “It started up in a snap, really quick,” confirmed Dan Ash, Senior Product Engineer for Utilities at the mill. “Our dream was that this boiler would start up as easily as the recovery boiler. We were not disappointed.”
“The learning curve for the BFB is much shorter than with the stoker boiler,” said Ash. “This is partially due to the boiler’s operating flexibility and level of
Fuel feeding ports in the boiler.
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