Cite abstract as Author(s) (2009), Title, European Aerosol Conference 2009, Karlsruhe, Abstract T083A33
Emission of particles from practical combustion devices burning methane/natural gas
Minutolo, P. 1, Prati, M.V. 2, Sirignano, M. 3, D’Anna, A.3
1
Istituto di Ricerche sulla Combustione, CNR, P.le Tecchio 80, 80125, Napoli, Italy
2
Istituto Motori, CNR, V.le Marconi, 1, 80125, Naples, Italy
3
Department of Chemical Engineering, University of Naples Federico II, P.le Tecchio 80, 80125, Naples, Italy
Keywords: methane/natural gas, particle size distribution, indoor/outdoor particles, industrial aerosols, CNG car
emissions.
produce particles; generally these particles have a
size of 2-3nm, spectroscopic behaviour typical of
small polycyclic aromatic compounds, and a
significant water affinity. In particular home burner
appliances resulted able to oxidize most part of
particle produced; the final effect is low emission in
terms of mass concentration, whereas the number of
these particles is relatively high. Beside of this, in the
10 nm–100 nm range, typical of primary soot
particles, the number concentration of the particles
measured at the exhaust of the combustion system is
of the same order of magnitude of the number
concentration of the particles present in ambient air.
Similar results have been found for the cook stoves
and catalytic heaters. In particular the partial
premixed flame stabilized on cook stoves produces a
reliable amount of particle with mean size of 3nm.
Finally a large concentration of particles is produced
and therefore emitted.
I.C. engine fuelled with CNG resulted to be,
as the other combustion devices, a low emission
technology. Measurements evidence that particles
with dimension larger than 5nm are comparable with
atmospheric background. However, in some
condition, the exhaust analyzed contained particles
with a mean size of 2nm; particles were present in
number concentration clearly higher than the air
room background, and comparable with values found
for the other devices investigated.
In conclusion methane, pure or in natural gas,
resulted to be a non-zero emission fuel. Real
combustion devices, conducted in their optimal
configuration, have showed that particles with size of
2-3nm are produced and emitted in relative high
number concentrations.
1.00E+09
1.00E+08
dN/dLnDp, #/cm3
Several studies have been conducted in last
years on the combustion of methane and natural gas
(NG), since they represent one of the source of
energy with a low emissions of greenhouse gases,
toxic combustion by-products and particulate matter.
In addition they can be widely used in different
combustion devices. However, recent studies have
showed that also these clean fuels can produce a
reliable number of particles.
A wide range of measurements on several real
combustion systems are here presented: from
domestic to industrial heater, together with gas
turbine and I.C. engines.
Premixed and diffusive burner configurations
used for home heating appliances have been studied
under various operating conditions. Advanced in-situ
optical diagnostics, based on laser induced emission
spectroscopy (LIE), and ex-situ measurements, based
on scanning mobility particle size (SMPS)
measurements, and particles collection by a waterbased sampling technique, have been used in order
to evaluate total particulate concentrations and size
distribution functions. Water samples, are analyzed
by light absorption and UV induced fluorescence
measurements. Moreover, also cook stoves and
catalytic heaters have been investigated, for their
effect on indoor pollution; for this device water
sampling and sizing by SMPS have been provided.
For all these applications natural gas was employed;
it was constituted by about 84% methane, 8% ethane,
2% propane, 5% nitrogen with others larger
hydrocarbons in low concentration.
In addition measurements have been
conducted on a I.C. engine fuelled with CNG and a
gas turbine fuelled with methane. A TapCon (or
Vienna) DMA equipped with a Faraday Cup
Electrometer (FCE) has been utilized to analyze the
exhaust gases. For I.C. engine also ELPI (Electrical
Low Pressure Impactor) has been used. The DMA, in
the utilized configuration, allows to detect particle,
down to 2nm, whereas ELPI is much more sensible
for particles larger then 20 nm. Experiments for I.C.
engine have been conducted at the exhaust of a Euro
3 S.I. car, driven on a chassis dyno bench. Different
regimes have been investigated in order to
understand the role of settings on particle production.
For all devices examined, experiments has
showed that methane combustion even when it is
conducted in overall lean premixed conditions can
1.00E+07
1.00E+06
1.00E+05
1.00E+04
1
10
100
Dp, nm
Figure 1. Typical PSDFs from cook stove(Δ), home
burner appliance in diffusive (○) and premixed (◊)
configuration and I.C. engine at constant speed(□).