Proceedings World Bioenergy 2010

Figure 3: Accumulated emissions from the boiler during
first 12 hours operation in the realistic sequence.
Figure 4: Accumulated emissions from the stove during
first 12 hours operation in the realistic sequence.
Accumulated total emissions during the six-days test
are plotted together with CO emission to show operating
cycles in figure 3 for the boiler and in figure 4 for the
stove. The boiler had higher number of start-up and stop
within the same time interval due to its higher nominal
power and smaller heat storage. Sudden rises of CO and
TOC emissions are shown during start-up and stop.
The NO emissions emitted during the stop period was
small in relation to the accumulated NO emission.
Particles during start and stop periods are not as
dominating as for CO and TOC although emissions peaks
occur. The contribution of start-up and stop phases to
total accumulated emissions are shown in figure 5. The
start-up and stop phases contribute 39% of the total PM
emission for the boiler and 23% of PM for the stove. The
amount of start-up and stop emissions are dominating for
CO and TOC emissions contributing by 95% and 89%
respectively at the 20kW boiler and 82% and 89 %
respectively at the 12 kW stove.
Figure 5: Accumulated start-up and stop emissions
during six days test
Figure 6: Emission concentrations for whole six days
test
The calculated total emissions related to fuel
consumption for the whole six days period are presented
in figure 6 divided between emissions during start-up and
stop periods and stationary operation. The 20 kW boiler
has higher emissions contributed partly by the higher
number of start-up and stop. Since the six-days should
give representative condition of a full year operation of a
domestic heating system, the average emissions
concentration from the tests should give representative
annual emissions factors for the heating devices. The
average annual emissions factors for the boiler are CO
(491 mg/MJ), NO (55 mg/MJ), TOC (54 mg/MJ) and
PM2.5 (93 mg/MJ) and for the stove CO (159 mg/MJ),
NO (54 mg/MJ), TOC (2 mg/MJ) and PM2.5 (39
mg/MJ).
4 CONCLUSIONS
Substantial parts of CO and TOC emissions are
contributed from start-up and stop while NO and particles
dominate during stationary operation. Higher operating
combustion power of the heating device in a domestic
heating system can results higher number of start-up and
stop and consequently higher annual emissions.
5 ACKNOWLEDGEMENT
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