This
study investigated the characteristics of both filterable
fine particulate matter (FPM) and condensable particulate matter (CPM)
emitted from coal-fired boilers (CFBs) and oil-fired boilers (OFBs)
via field sampling. FPM and CPM samples were collected using USEPA
Method 201A and Method 202, respectively. Mass concentrations and
chemical compositions (including water-soluble ions, metal elements
and carbon contents) of collected PM2.5 samples were analyzed.
The results show that PM2.5 (FPM + CPM) emission concentrations
for CFBs and OFBs are 20.2 ± 10.4 and 157 ± 82.7 mg/Nm3, respectively. In terms of the emission factor, emission
of FPM from OFBs is 307.4 ± 50 g/kL of oil and from CFBs is 57.1
± 13.8 g/t of coal. Significantly higher concentrations are emitted
from OFBs than from CFBs due to the reason that better control devices
are installed in most CFBs. The average CPM fraction constitutes 58.7
and 54.8% of PM2.5 for CFBs and OFBs, respectively, showing
that CPM from the boilers contributes a significant fraction of PM2.5 emissions. FPM sample analysis reveals that SO4
2– is the primary characteristic of water-soluble
ion and occupies 64.2 and 80.6% of total water-soluble ions for CFBs
and OFBs, respectively. SO4
2– is a main
contributor of ions, while NO3
– follows.
The species in CPM are dominated by water-soluble ions, including
SO4
2–, NO3
–, and NH4
+. The results indicate that CPM is
formed primarily by water-soluble ions. The results also show that
organic carbon (OC) concentrations are predominant for CFBs, and elemental
carbon (EC) is predominant for OFBs.