Experimental study of PM emissions from wood pellet stoves with an innovative burning pot

Abstract

In this study, results of an extensive set of experiments on a wood pellet stove model equipped with innovative burning pots are presented. Tests have been performed to investigate the relations between design data and operation parameters of the stove and its emissions. In particular, carbon monoxide (CO) and particulate matter (PM) emissions are correlated to the burning-pot depth. The burning pot A, adopted by AICO S.p.A, allows to obtain near-to-zero CO emissions and low PM emissions: however, PM emissions reduction with respect to standard burning pots is not as enhanced as CO emission reduction. Here it is shown that a further reduction of PM emissions (down to 6-16 mg/Nm3) can be attained increasing the burning pot depth. Experiments show also an increment of PM emissions in subsequent tests in the same day: there is an apparent dependence of PM release on the time from ignition. It is likely that this effect is due to ashes accumulation on the bottom of the burning pot and to their interaction with the primary air stream that flows over them.

The Effect of Flue Gas Recirculation on CO, PM and NOx Emissions in Pellet Stove Combustion

“…The flow rate of combustion air was adjusted by the speed of the flue gas extraction fan at the outlet of the stove. In its standard configuration, the stove was equipped with the "type A" burner pot described by Polonini et al [9] and patented by AICO S.p.A. [37]. In the tests carried out for the present study, the stove has been equipped with a deeper burner pot, identified as "type B" [9] and illustrated in Figure 1.…”

“…In its standard configuration, the stove was equipped with the "type A" burner pot described by Polonini et al [9] and patented by AICO S.p.A. [37]. In the tests carried out for the present study, the stove has been equipped with a deeper burner pot, identified as "type B" [9] and illustrated in Figure 1. The use of this model of burner pot was previously found to be associated with lower CO and PM emissions if compared with traditional, less deep components [9].…”

“…In the tests carried out for the present study, the stove has been equipped with a deeper burner pot, identified as "type B" [9] and illustrated in Figure 1. The use of this model of burner pot was previously found to be associated with lower CO and PM emissions if compared with traditional, less deep components [9]. The stove was airtight.…”

“…The experimental investigation has been performed in the framework of a collaboration between the University of Brescia and AICO S.p.A., a pellet stove manufacturer, and it is a part of a project for the reduction of CO, PM and NO x emissions. The stove model used during the tests is indeed the result of an optimization process on the burner pot and the positions of air inlets presented in other publications of the authors [9,36]. This process led to a substantial reduction in CO, an appreciable reduction in PM, and a minor reduction in NO x .…”

“…In addition to fuel properties, burner pot geometry, burning power, air inlet positions, air staging, and excess air also influence emissions and performances of solid fuel combustion. As concerns burner pot geometry, differences in dimensions, air inlet positions, air inlet ratios and depth can lead to important variations in CO and PM emissions [9]. For each stove, there is a specific range of burning power that optimizes combustion, as demonstrated by several studies-see, for example, the works by Morán et al [10], Colom-Díaz et al [11] and Fernandes et al [12], in which the same appliance was tested at different burning powers and an optimum interval was identified for the minimization of CO emission and fly ashes.…”