guus pemen, bert van heesch, wilfred hoeben faculty of
TRANSCRIPT
Streamers and their applications.
Guus Pemen, Bert van Heesch, Wilfred HoebenGuus Pemen, Bert van Heesch, Wilfred Hoeben
Faculty of Electrical Engineering
Pulsed corona discharges
10 ns
20 ns
10 ns
20 ns
10 ns
20 ns
10 ns
20 ns
Primary streamers
Secondary or late streamers
(can be avoided by using
short pulses)
PAGE 127-Oct-2010
fast ICCD
end-on
views
30 ns
40 ns
30 ns
40 ns
30 ns
40 ns
30 ns
40 ns
Quantification of O-radical yields
Primary yield increases if
velocity is increased
(because local E-field
increases and consequently
so does the electron
energy)
PAGE 227-Oct-2010
Secondary or late streamers
(can be avoided by using
short pulses)
Quantification of O-radical yields
7.0 mole/kWh corresponds
to 5.3 eV/molecule.
Theoretical cost to produce
an O* radical is 3 eV.
PAGE 327-Oct-2010
O* radical yield as function of voltage and pulse
width. The rise rate of the pulses was fixed 2.2-
2.7 kV/ns. DC bias: 0-20 kV.
Thus more than half of the
available energy is used to
produce O* radicals
Emission intensities of SPS(0,0) and FNS(0,0)
secondary
streamer
Em
issi
on
in
ten
sity
(A
.U.)
-0,6
-0,4
-0,2
0,0
0,2
N2, SPS(2,5)
394.30 nm
N2, SPS(3,6)
389.46 nm
N+
2, FNS(0,0)
391.44 nm
Electron energies during primary
streamer propagation are assumed
to be much larger than the energy
in the secondary streamer
PAGE 427-Oct-2010
streamer
primary streamer
Em
issi
on
in
ten
sity
(A
.U.)
Wave length (nm)
-1,2
-1,0
-0,8
-0,6
388 390 392 394 396
Electron energy for N2+(B2∑u
+) generation by direct electron impact excitation
from the N2 ground state is 18.7 eV. It is assumed that the stronger the
FNS(0,0) emission, the larger the average electron energy.
in the secondary streamer
development.
Experimental setup
Rise-time 7.7 ns, FWHM 16 ns
Peak value 56.6-57.9 kV
27-Oct-2010 PAGE 5
Optical characteristics – air
Time integrated - shutter 30 ns
PAGE 627-Oct-2010
11.6 mm
56.6 kV, 50 A
16.4 mm
57.2 kV, 22 A21.6 mm
57.9 kV, 8.5 A
28.4 mm
57.9 kV, 3ALonger gap distance:
- Less current, more branches,
- Smaller diameter, smaller velocity.
Optical characteristics – air
Time resolved - 11.6 mm gap, shutter 0.5 ns
Primary streamer
development in
about 2 ns (6.106 m/s)
PAGE 7
ΔT = 0 ns ΔT = 0.5 ns ΔT = 1 ns ΔT = 2 ns
ΔT = 5 ns ΔT = 8 ns ΔT = 20 ns ΔT = 40 ns
27-Oct-2010
Secondary streamers,
total duration about
40 ns.
Optical characteristics – air
Time resolved - 21.6 mm gap, shutter 1 ns
Primary streamer
development in
about 6 ns (4.106 m/s)
ΔT = 0 ns ΔT = 2 ns ΔT = 5 ns ΔT = 6 ns
ΔT = 6 ns ΔT = 8 ns ΔT = 20 ns ΔT = 25 ns
27-Oct-2010 PAGE 8
Little secondary
streamers, total
duration about 25 ns.
Laser absorption – air
Visualization of density gradients (shockwaves)
Formation of elliptical
shockwaves at anode.
Followed by hemispherical
ones at the cathode.
anode
Initial velocity 880 m/s.
11.6 mm gap
27-Oct-2010 PAGE 9
cathode
ΔT = 0 ns ΔT = 840 ns ΔT = 5.9 μs
ΔT = 10.8 μs ΔT = 21.9 μs ΔT = 306 μs
Initial velocity 880 m/s.
“Slows” down to 420 m/s
after about 20 μs.
Apparently sufficient
energy has been deposited
in the gas to create
substantial gas heating.
Applications
ODOR
VOLATILE CHEMICAL COMPOUNDS
FINE DUST, NOx, SOx
VIRUS AND MICRO-ORGANISMS
DIOXINS, HEAVY METALS
AIR
Food, Agro
Petrochem
Traffic, Power plants
Hospitals, Agro
Incinerators, P plants
Time to demonstration
SEISMIC, FRACTURE
VIRUS AND MICRO-ORGANISMS
CHEMICAL COMPOUNDS
GAS CONDITIONING, REFORMING
PLASMA CATALYSIS
PLASMA COMBUSTION, GASIFICATION
WATER
PROCESS
Marine Industry
Food, Waste water
Waste + Proc. water
Green+Proc. Industry
Green+Proc. Industry
Powergen, Recycling
27-Oct-2010 PAGE 10
Application – syngas conditioning
Biomass
CO
Sunlight
Gasification
Biomass
CO
Sunlight
Gasification
Fuel
CO2
Electric Power
Gasification
CO + H2 + CH4 +CO2 + N2 + tars
Fuel
CO2
Electric Power
Gasification
CO + H2 + CH4 +CO2 + N2 + tars
27-Oct-2010 PAGE 11
Tar compositionComponents with high individual dewpoints cannot be tolerated
Component Formula mass % in
tar
Tdew,wet
(oC)
Benzene C6H6 67.56 32
Toluene C7H8 1.28 32
Naphtalene C10H8 17.86 33
Penol C6H6O 0.12 32
Pyrene C16H10 2.94 114
Phenanthrene C14H10 4.27 91
CH3
OH
toluene phenol
14 10
Fluorene C13H10 0.53 35
Indene C9H8 1.35 32
4-Methylstyrene C9H10 0.04 32
1-Methylnaphtalene C11H10 0.13 32
2-Methylnaphtalene C11H10 0.26 32
Biphenyl C12H10 0.50 12
Acenaphtalene C12H8 0.29 14
Fluoranthene C16H10 2.83 113
Pyridine C5H5N 0.04 32
Dewpoint of each tar component, based on total tar concentration of 20 g/Nm3, at 1 bar.
naphthalene
phenanthrene
27-Oct-2010 PAGE 12
Lab investigations (1/3)
High-Voltage
Condensor
FTIR
FTIR
H2
N2
Vacuum pump
Stack
Coronareactor
Heating tapes +insulation
1.5 m,
15 cm dia
Condensor
GC
Recirculationfan
Coolertar
injectionPressuregauge
Biogas
CO
CO2
H2
Pulsed power:
20 - 40 kV
5 ns rise time, 50 ns wide
0.4 J/pulse
1 – 100 pulse/second
Properties:
Volume 56 L
Reactor volume 20 L
Temp 200 – 800 oC
velocity 6 – 12 m/s
Measurements:
FTIR, pressure,
Temperature, SPA,
Pulse energy, # pulses
Model compound:
Naphthalene C10H8
27-Oct-2010 PAGE 13
Lab investigations (2/3)
Corona Reactor
Window for FTIR
Tar Injector
Corona Reactor
Window for FTIR
Tar Injector
Effect of temperature on naphthalene
removal in synthetic fuel gas
60
80
100
Rem
ain
ing f
raction
(%
) 200 degr.C, dry
200 degr.C, wet
biogas 400400 degr.C, dry
60
80
100
Rem
ain
ing f
raction
(%
) 200 degr.C, dry
200 degr.C, wet
biogas 400400 degr.C, dry
FanFan
0
20
40
0 200 400 600 800
Corona energy density (kJ/Nm3)
Rem
ain
ing f
raction
(%
)
0
20
40
0 200 400 600 800
Corona energy density (kJ/Nm3)
Rem
ain
ing f
raction
(%
)
27-Oct-2010 PAGE 14
Lab investigations (3/3)
200
250
300
350
400
Co
ron
a e
ne
rgy d
en
sity
for
90
% r
em
ova
l (k
J/N
m3)
fuelgas (N2 + 12% CO
2 + 20% CO + 17% H
2 + 1% CH
4)
N2 + 10% CO
2 + 10% CO + 10% H
2
N2 + 10% CO
2 + 10% CO
N2 + 10% CO
2
Most favourable
kinetics at 400 oC.
Hydrogen hampers
200 300 400 500
0
50
100
150
200
Co
ron
a e
ne
rgy d
en
sity
for
90
% r
em
ova
l (k
J/N
m
Temperature (oC)
Effect of gas composition and temperature.
Hydrogen hampers
the process.
27-Oct-2010 PAGE 15
Mechanism (1/2)
Dominant reactions (by order of importance):
N2(A) + C10H8 —> products
N(2D) + C10H8 —> products
N2(A) + N2(A) —> N2 + N2(A)
O + C10H8 —> H + C10H7O
CO + N2(A) —> N2 + CO
CO2 + N —> CO + NO 0.6
0.8
1
fra
ctio
n r
em
ain
ing
12% CO2 + 20% CO + 17% H2 + 1% CH4 + N2
N2
2
CO2 + N(2D) —> CO + NO
NO + N —> O +N2
NO + NH —> H + N2O
NO + NH —> OH + N2
NO + NH —> O + N2H
O + H2 —> H + OH
O(1D) + H2 —> H + OH
OH + C10H8 —> H2O +C10H7
H2 + C10H7 —> H + C10H8
diffusion —> C10H8
0
0.2
0.4
0 50 100 150 200 250 300
Corona energy density (kJ/Nm3)
fra
ctio
n r
em
ain
ing
27-Oct-2010 PAGE 16
Mechanism (2/2)
Example of an important naphthalene decomposition pathway.
+ H
+ H
+ OH
+ OO
.
.
+ O
+ H
+ H
+ OO
O H
C H CH ..
.
Backformation reactions, involving H and OH radicals, seem
to hamper the process.
Thats why the energy requirements are higher for gas
compositions containing H2.
27-Oct-2010 PAGE 17
Demonstrator
PAGE 1827-Oct-2010
20 kW corona power.
10.000 – 30.000m3/hr
Acknowledgements:
PAGE 1927-Oct-2010
• Frank Beckers, Oranjewoud
• Hans Winands, TNO
• Zhen Liu, Zhejiang University
• Sreejit Nair, Dow Chemical
• Luc Rabou, ECN