Abstract
Factors associated with the determination of continuous
aerosol size
distribution functions with
compressible flow low pressure impactors, including the
determination of the
kernel functions for the
submicron stages, data inversion and the validity of the
determined continuous
submicron size
distribution functions, were studied. Methods to
determine mass and composition
size distributions of
aerosols emitted from combustion processes with low
pressure impactors were
developed. Impactors
were used to characterize aerosols emitted from the real
scale hospital refuse
incineration and pulverized
coal combustion processes.
Collection efficiency curves for the submicron stages of
the modified
University of Washington Mark 5
low pressure impact (KLPI) and Berner type low pressure
impactor (BLPI HAUKE
25/0.015) were
determined experimentally with singly charged,
monodispersed liquid di octyl
phtalate aerosol particles.
Calibration results indicate that the steepness of the
efficiency curve and the
square root value of the cut
Stokes number of compressible flow impactor stages depend
on the stage pressure
ratio as well as on the
distance between the jet and collection plates. This
behaviour is contradictory
to the collection
characteristics of the ambient pressure, incompressible
flow impactor stages.
Collection efficiency curves
for stages operating at the pressure ratios from
0.45-0.65 and at upstream
stage absolute stagnation
pressures of 7-35 kPa are very sharp for both impactors.
Stages operating at
pressure ratios of 0.65-0.95
and at upstream stage absolute stagnation pressures of
51-87 kPa have curves
with reduced sharpness of
cut, with the detoriation of the size resolution being
pronounced for KLPI.
This is due to the larger
distance between the jet and collection plates of KLPI.
Errors due to data inversion with the method based on
constrained
regularization were studied by
inverting multiple sets of both error free and noisy
unimodal submicron aerosol
data sets simulated for
BLPI, KLPI and LLPI (the impactor designed at the
University of Florida) low
pressure impactors.
Inverted results for error free data with small (2.5 %)
error estimate were
very close to input
distributions. When the normally distributed random error
level and data error
estimates were equal to or
smaller than 10 % of the stage mass concentrations, the
majority of inverted
spectra were unimodal close
to the input distributions.
The inversion of impactor data from laboratory instrument
comparison
experiments using experimental
stage mass error estimate indicates that only BLPI kernel
functions are
sufficiently accurate to yield
unimodal distributions close to those determined with the
differential
electrical mobility (DMA) method.
When the stage mass error estimate was increased beyond
the experimental error,
unimodal spectra were
also found for KLPI and LLPI.
Mass and Na, K, S, Cd, Zn and Pb size distributions of
aerosols emitted from
the hospital refuse
incineration process equipped with a cleaning cyclone
were bimodal, with the
fine mode at about 0.1 to
0.2 ~m and the coarse mode between 6 and 10 ~m. Mg, Al,
Cl, Ca, Ti and Fe size
distributions were
unimodal, with these elements found only in coarse mode
particles. Bimodal
distributions indicate partial
vaporization and nucleation of inorganic compounds.
Significant fractions of
toxic trace metals were
vaporized, i.e. 23-80 % of particle bound Zn, 62-77 % of
Cd and 7-74 % of Pb
were found in the
fine mode particles.
Mass and Na, Mg, Al, Si, S, K, Ca, Ti, Fe, V, Mn, Cu, Zn,
Sr, Cd and Pb size
distributions of aerosols
emitted from the combustion of pulverized, bituminous
coal from Poland were
bimodal. When samples
were collected after the electrostatic precipitator,
geometric mass mean
diameters of fine and coarse
modes were about 0.05 and 2 ~m, respectively. About 5 %
of particle mass and
particlebound Na, Mg,
Al, Si, Ti, Fe, Mn and Zn were found in the fineparticle
mode. S, Ca, V, Cu,
Sr, Cd and Pb were
enriched in the fine mode particles, i.e. about 80 % of
the particlebound S, 17
% of Ca, 23 % of V, 22
% of Cu, 11 % of Sr, 23 % of Cd and 9 % of Pb were in the
submicron fine mode
particles. The flatness
of the Mg, Al, Si and Ti mass fraction size distributions
suggests vaporization
and subsequent nucleation
of the fraction of these ash components during the
combustion of single
pulverized coal particles.
Original language | English |
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Qualification | Doctor Degree |
Awarding Institution |
|
Award date | 1 Feb 1992 |
Place of Publication | Espoo |
Publisher | |
Print ISBNs | 951-38-4064-6 |
Publication status | Published - 1992 |
MoE publication type | G5 Doctoral dissertation (article) |
Keywords
- aerosols
- impactors
- low pressure
- spectroscopy
- combustion products
- particle size distribution
- size determination
- air pollution
- flue gases
- coal
- environmental protection
- compressible flow
- experimentation
- methods
- refuse
- incinerators
- hospitals