, 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)