Boilers Emissions Under Different Stack Configurations at a School in Saranac Lake, NY

A 1.7 MMBTU wood pellet boiler was installed in a container outside the Petrova Elementary School, Saranac Lake to provide heat to the building and reduce the dependence on fuel oil. The exhaust stack was initially 25’ high, i.e. less than the school building height and the effluent stream could then enter through the building air intakes. Computational fluid dynamics modeling was performed to assess the emission impacts for a taller stack. Results showed if the stack height was raised to 45’ (10’ above the roof), the plume would loft over the building and avoid the air intakes. However, the USEPA best practices guidelines suggested the stack should be 2.5 times the height of the structure. From December 2015, a sampling campaign was conducted to evaluate if the increased stack height was sufficient to reduce the air pollutant concentrations at the roof top and, thus, if the stack configuration was sufficient to avoid boiler exhausts be drawn into the school. CO, black carbon and PM were measured on the roof of the school. Weather and wind parameters were also measured. Air pollution data were recorded in periods without boiler emissions and then with both the short and taller stacks in place. A series of chemometric tools were thus applied for: (i) comparing the levels of pollutants during different stack configurations; (ii) investigating the relationships among pollutants and boiler operation modes; (iii) detect possible effects of meteorology on the levels of air pollutants. The results of this evaluation will be presented.