Boiler Blowdown Heat Recovery Project Reduces Steam System Energy Losses at Augusta Newsprint

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Summary
The boiler blowdown process involves the periodic or continuous removal of water from a
boiler to remove accumulated dissolved solids and/or sludges. During the process, water is
discharged from the boiler to avoid the negative impacts of dissolved solids or impurities
on boiler efficiency and maintenance. However, boiler blowdown wastes energy because
the blown down liquid is at about the same temperature as the steam produced. Much of this
heat can be recovered by routing the blown down liquid through a heat exchanger that
preheats the boiler's makeup water. A boiler blowdown heat recovery project at Augusta
Newsprint Company’s Augusta, Georgia, mill will save almost $31,000 annually in fuel costs.

Plant Overview
The Augusta Newsprint mill is part of a joint partnership between Abitibi Consolidated and
the Woodbridge Company, Ltd. The mill produces up to 440,000 metric tons of standard
newsprint each year from southern pine and recycled newspaper and magazines. The
mill has 2 paper machines and employs 380 workers.
Abitibi-Consolidated is a global leader in newsprint and uncoated groundwood papers
with ownership interests in 27 paper mills in Canada, the United States, the United
Kingdom, and Asia (including its 50 percent interest in Pan Asia Paper Company). The
company also has ownership interest in 22 sawmills, 2 remanufacturing facilities, and
a market pulp mill. Abitibi-Consolidated employs approximately 18,000 people and
supplies products in nearly 100 countries.

Project Overview
Blowdown is essential for continued operation of any steam boiler. However, blowdown
represents an energy loss to the steam system. Although the blowdown rate at Augusta
Newsprint is typical of most boilers, recovering the heat resident in the blowdown stream
can save energy. Currently, the continuous boiler blowdown is routed to a flash tank
where the pressure is reduced from 300 pounds per square inch gauge (psig) to
approximately 55 psig. Flash steam produced in the pressure reduction process is
piped into the deaerator to offset deaeration steam demand. This operation is currently
saving the mill about $10,000 per year in fuel costs. Additional energy can be recovered
from the contaminated condensate exiting the flash vessel. The condensate dissipates
energy that could be utilized to preheat makeup water. Figure 1 shows a schematic of
the boiler blowdown system before and after heat exchanger installation.