The #3
Power Boiler is located in the Steam Plant on the banks of the
Kaministiquia River. Originally built in 1963, this boiler was designed to burn coal and wood waste to generate high-pressure steam for electricity generation and pulp and paper manufacture This boiler burns wood waste that is either generated from the mill or purchased from sawmills.
The wood waste, which consists primarily of bark and oversized chips and knots, is fed into the boiler on a continuous basis where it is burned on a combustion bed. The boiler is lined with tubes filled with water, which generate steam when they come into contact with heat. The steam, which is at a very high pressure (850 psi) goes into the mill’s steam system and is used to generate electricity in one of three turbines or is used in the process.
The
ash (similar to ash from a home woodstove) is removed from the bottom of the boiler by grates and collected in a silo. The local agricultural community uses the collected ash to adjust the pH of the soil.
To address concerns regarding particulate from this boiler, the existing pollution control equipment was upgraded in 1995. A new
venturi scrubber was installed which reduced
particulate emissions from this boiler by over 95%.
The scrubber removes particulate by spraying the dirty
flue gas with a fine spray of high-pressure water. The particulate is captured in the water, and the dirty water drops to the bottom of the scrubber for collection. The clean gas is exhausted to the atmosphere. Because water is used for scrubbing, the gas is saturated with moisture, which results in a large white cloud-like plume from the stack. The dirty water that is collected in the bottom of the scrubber is put through a clarifier that settles out the particulate (ash). This material is sent to a licensed
landfill.