Power Boiler # 10 (presumably the last in a long line of power boilers 1-9) makes up the difference between the recovery furnace’s output and the steam demands of the mill... most of the time. It is a very flexible boiler. It has the capability to combust fossil fuels only (including RFO), wood only, or a mixture of fossil fuel, wood, and solid fuels. Currently, this boiler is fueled primarily by wood waste, but recycled fuel oil (RFO) accounts for about 30% of the heat input. Also combusted are the primary clarifier sludge from the water treatment facility and old corrugated container (OCC) rejects from the OCC plant. It has a heat input capacity of about 360 mmBtu/hr and makes high pressure steam suitable for input to the cogeneration turbine.
For the technically inclined, this is a spreader stoker type boiler with horizontally opposed overfire air ports and tangential oil burners downstream of the grate. Wood waste (primarily) is fired on the grates while the RFO is fired at the tangential burners.
Emissions and Controls
The pollution control equipment on Power Boiler #10 is comprised of a multiclone dust collector to filter out the larger particulates, followed by a Turbotak wet scrubber , installed 1988, to help control the smaller particulate emissions as well as acidic gases, mists and odors.
The main pollutants that get past this equipment are (in order of tonnage) carbon monoxide (CO), sulfur dioxide (SO2), nitrous oxides (NOX), and small particulates (PM2.5). There is also a significant amount of hydrochloric acid aerosol (HCl) emitted as well as some VOCs and a small amount of heavy metals.
There is close to 20 tons per day of ash disposed of at PTPC's landfill, and most of that is from Power Boiler #10 since it is the only boiler that burns wood waste. Included is "fly ash" filtered from the flue gases by the multiclone collector, as well as the "bottom ash" which settles to the bottom of the combustion unit.
Trinity BART Report, 2007: http://www.ecy.wa.gov/programs/air/globalwarm_RegHaze/BART/PTPC2007_12_19_PTPC_BART_Determination_Submittal.pdf
Trinity BART Report Addendum: http://www.ecy.wa.gov/programs/air/globalwarm_RegHaze/BART/PTPC_BART_Addendum.pdf
DOH Health Consultation, 2008: http://www.atsdr.cdc.gov/hac/pha/PortTownsendPaperCorp/Port_Townsend_Paper_Corporation%20HC%207-1-2008.pdf