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, 30, 5 (2006) 230 235
,1
2006 5 19 ; 2006 9 12
Moving Electrode Type Electrostatic Precipitator Having a Pulse Charging Fixed-Electrode Section
Toshiaki MISAKA*,1, Tadashi OURA* and Minoru YAMAZAKI*(Received May 19, 2006; Accepted September 12, 2006)
The electrostatic precipitator composed of a fixed electrode section with pulse energization, followed by the movingelectrode section to cope with handling an extremely high resistive dust. A pulse energization for the fix electrode section was studied for the purpose of improving the collection efficiency. The relationship between pulse waveforms and theircollection efficiencies has been experimentally investigated for a cylindrical electrostatic precipitator. For handling thehigh resistive dust greater than 1012 cm, the optimum pulse waveforms superimposed of DC voltage and DC current were revealed. The experimental results for a coal fired boiler application indicated that the optimum DC current, the pulse voltage, and pulse frequency exist depending on dust resistivity. Suitable choice of pulse waveform could lead toachieve a significantly higher collection efficiency than that of the conventional DC energization.
1.
1
2-4
5
6
7-10
11
* 170-84661-13-2
Hitachi Plant Technologies, Ltd. 1-13-2 Kita-Otsuka, To-shima-ku, Tokyo, 170-8466 Japan
1 toshiaki.misaka.sn@hitachi-pt.com
J. Inst. Electrostat. Jpn.
231 (39)
2.
2.1
12
1
310mm
1.3m 1
1m
2
250m3/h
2.53m 2
1m/s
120 7g/m3N
3
1
213
13
0 -60kV
30 500 s 50 600pps
3
14
1Table 1 Characteristics of sampled dust
SampleFly ash
Dust resistivity ( cm)
Mean diameter( )
A 3.8 1010 1.2 1011 16.0 B 9.5 1011 7.0 1013 16.0 C 9.8 1012 1.1 1014 12.3
2.2
4 -30kV
9.8 1010 cm
App
lyvo
ltage
(kV
) -80-60-40-200
20
Curre
nt(A
)-2-1012
40 60 80 100 0Time ( s)
3Fig.3 Pulse voltage and current waveforms.
1 2Fig.1 Experimental setup for the pulse-charging electrostatic precipitator. Fig.2 The probe for dust resistivity
measurement.
High resistivity meterDust resistivity probe
Tubular type electrostatic precipitator
SCA=33.7s/m
Sample dust feederCi=1 10g/m3N
Water injector
FanVp=0 -50kVPw=30 500 sPf=50 600pps
Fabricfilter
Coupling capacitorOutlet dust monitor
Gas heater
Inlet dust monitor
-60kV/-10mA
mA
1,00
0
1,30
0
DC Power supply
To highresistivity meter
To vacuum pump
Center electrode
Nozzle
Cylindrical electrode
Pulse Power supply
30 5 2006232 (40)??, ?(200?) 00 00
- 3 -
3.3 1012 cm 0.05mA/m2
1.1 1014 cm
0.03mA/m2
1012 cm
5
9.8 1011 cm
1.1
1013 cm
-35kV
4.2 1013 cm -30kV
1.1 1014 cm -20 kV
6
9.8 1011 cm
1.1 1014
cm
2.1 1013 cm
100pps
Fig.4 DC current vs. collection efficiency.
DC current (mA/m2) 0 -0.05 -0.1 -0.15 -0.2 -0.25 -0.3
Colle
ctio
n ef
ficie
ncy
(%)
0
50
90
95
99
70
97
5.2 1010
4.2 1013
Vp=-30kV Pw=80µs Pf=100pps
1.1 1014 cm
1.1 1013
3.3 1012
1.0 1012
9.8 1010
Fig.5 Pulse voltage vs. collection efficiency.
Pulse voltage Vp (kV) 0 -10 -20 -30 -40 -50
Colle
ctio
n ef
ficie
ncy
(%)
0
50
90
95
99
70
97
1.1 1013
Pw=80µs IB=0.05mA/m2
Pf=100pps
1.1 1014 cm
4.2 1013
9.8 1011
Fig.6 Pulse frequency vs. collection efficiency and current.
Pulse frequency Pf (pps) 0 100 200 300 400 500 600
Colle
ctio
n ef
ficie
ncy
(%)
0
50
90
95
70
97
2.1 1013
Vp=-30kV Pw=80µs IB=-0.05mA/m2
1.1 1014 cm
9.8 1012
9.8 10100
0.05
0.1
Curre
nt (
mA
/m2 )
0.15
9.8 1011 cmPw=80µs IB=-0.05mA/m2
233 (41)
- 4 -
7
9.8 1011 cm
9.8 1012 cm
1.1 1014 cm
30 s
8
0.2mA/m2
1013
cm
1 1013 cm
Deutsch 14
8
90 70
13
3.
3.1
9 530t/h
1 300mm
Fig.7 Pulse width vs. collection efficiency.
Pulse width Pw ( s) 0 20 40 60 80 100
Colle
ctio
n ef
ficie
ncy
(%)
0
50
90
95
99
70
97
1.1 1014 cm
4.2 1013
9.8 1011
120 140
2.1 1013
9.8 1012
Vp=-30kV IB=0.05mA/m2
Pf=100pps
Fig.8 Comparison of collection efficiency on charging methodes
99
1011
95
90
Dust resistivity ( cm)
50
Colle
ctio
n ef
ficie
ncy
(%)
70
97
1012 1013 1014
Intermittent energization I=-0.2mA/m2
DC energizationI=-0.2mA/m2
Pulse energization
30 5 2006234 (42)
??, ?(200?) 00 00
- 5 -
2
3.2
(1)
10
2
5 1012 cm 3 1013 cm
-0.027mA/m2
-0.027mA/m2
11
5.0 1012 cm
-35kV 3.0 1013 cm
-28kV
(2)
5.0 1011 cm 3.0
1013 cm 12
1.0 1013 cm
91.0 94.2
97.5
64.4 27.7
(3)
2
1
1310
Fig.10 DC current vs. outlet dust loading.
Current (mA/m2)
Out
let
dust
dens
ity
(g/ m
3 N)
0. -0.01 -0.02 -0.03 -0.04
5.0 1012 cmVp=-35kV Pf=120pps Pw=150 s0
0.1
0. 2
0. 3 3.0 1013 cmVp=-30kV Pf=120pps Pw=100 s
Fig.11 Pulse voltage vs. collection efficiency.
Pulse voltage Vp (kV)
Colle
ctio
n ef
ficie
ncy
(%)
0 -10 -20 -30 -40 -500
50
90
95
99
70
97
99.5
2.5 1012
3.0 1013 cm
5.0 1012
Pw=100µs Pf=120ppsIB=-0.035mA/m2
Coal fired boiler
Stack
Fixed electrode section
9Fig.9 Field test facilities for the coal fired boiler.
Co=0.2g/m3N
Ci= 15g/m3N
IDF
DC power supply
Pulse power supply
Inlet dust monitor
De SOxAir
heater
Outlet dustmonitor
DC power supply
Moving electrode section
Q=567,000m3N/hTg=153
- 6 -
1
13 2
1
(1) 1
(2)
1
4.
1012 cm
-0.027mA/m2 -28 -35kV
1
1)
2) 30 (2006) 128 3) ,
30 (2006) 185 4) , 30(2006)2235) 2 (1978) 596) H.J. White Trans. AIEE,71,pt1, p.326 (1952)7) K.S.Kumar, P.L.Feldman, H.I.Milde, C.Schbert Proc.
IEEE-IAS 79:6G, p.13338) P.Lausen, H.Henriksen, H.Hoegh Petersen Proc. IEEE-IAS
79:6B, p.163 (1979) 9) 40 (1988) 155 10) ES-82 p.99
(1982) 11) 9 (1985) 31512) ’69,
p7 (1996) 13) 1
(1986) 14) 12 (1988) 433 15) W. Deutsch Ann. d. Phys., 68 (1922) 335
13Fig.13 Comparison of collection efficiency by charging methods.
99
1011
95
90
Dust resistivity ( cm)
50
Colle
ctio
n ef
ficie
ncy
70
97
1012 1013 1014
99.5
0
2F: DC energizatio
1F:Intermittent energization1F:DC energization
1F:Pulse energization1F collection efficiency(Measured)
2F collection efficiency(Calculated)
12Fig.12 Comparison of collection efficiency by charging methods.
99
1011
95
90
Dust resistivity ( cm)
50
Colle
ctio
n ef
ficie
ncy
70
97
1012 1013 1014
99.5
0
1F:Intermittent energization
1F: DC energizatio
1F:Pulse energization
2F: DC energizatio
235 (43)