investigation of electric wind in the corona charging unit of a novel electrostatic collector

Forschungszentrum Karlsruhein der Helmholtz-Gemeinschaft

Investigation of Electric Wind in the Corona Charging Unit of a Novel Electrostatic Collector

An. M. Bologa, H.-R. Paur, K. Woletz

Forschungszentrum Karlsruhe GmbH,

Institut für Technische Chemie,

Postfach 3640, D-76021, Karlsruhe, Germany

5th Electrohydrodynamics International WorkshopPoitiers, France,

August 30-31, 2004


Flue gas cleaning

Separation process in the one stage ESP

Separation process in the CAROLA collector

Separation process in the two stage ESP

Advantages of the CAROLA:

-One operation electric field;-Low operation voltage;-Strong electric field and effective particle charging in the charging zone; -Module principle of design.


CAROLA collector

Particle charging

Gas

Charged particle transport

Charged particle collection


Test of the CAROLA collector for oil mist

Particle number concentration and fractional collection efficiency,Q=520 m3/h, U=16,4 kV, I= 6,2 mA

0,0E+00

1,0E+05

2,0E+05

3,0E+05

4,0E+05

5,0E+05

0,1 1 10Xm [µm]

Par

ticl

e co

nce

ntr

atio

n [

1/cm

³]

0

20

40

60

80

100

raw gas

collection efficiency

clean gas

Fra

ctio

nal

co

llec

tio

n e

ffic

ien

cy [

%]


Task of investigations

The behaviour of the particles in the charging zone depends on:• physical properties of the gas and particles,• gas velocity, temperature, relative humidity• charging system geometry,• voltage and corona current,• electrohydrodynamic phenomena, • etc.

In the present article an electric wind in the charging system of the CAROLA collectors is investigated.


Test facilities


Results of investigations

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Voltage, kV

Cor

ona

curren

t, m

A

Dn= 50 mm, no air flow

Dn= 50 mm, with air flow

Dn=40 mm, no air flow

Dn=40 mm, with air flow

Dn=30 mm, no air flow

Dn=30 mm, with air flow

Current-voltage characteristics of the ionization section, flow rate for Dn=0,05 m is up to 106 m3/h, for Dn=0,04 m is up to 68 m3/h and for Dn=0,03 m is up to 38m3/h


Electric wind and air velocities

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Measurement point

Ele

ctric

win

d ve

loci

ty, m

/s

no air flow with HV with air flow, no HV with air flow, with HV

Maximum electric wind and air velocities in the measurement points, Dn=0,05 m and H=0,03 m


Influence of the distance H to electric wind velocity

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1,5

2

2,5

0 1 2 3 4

Measurement point

Ele

ctric

win

d ve

loci

ty, m

/sH=30 mm H=50 mm H=60 mm H=90 mm

Maximum electric wind velocity for different distances H


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0,5

1

1,5

2

2,5

0 20 40 60 80 100

Distance H, mm

Ele

ctric

win

d ve

loci

ty, m

/s

point 1 point 2 point 3

Dependence of maximum electric wind velocity on the distance from the charging system, U=19,9 kV, I=0,36 mA


Influence of applied voltage on electric wind velocity

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Voltage, kV

Ele

ctric

win

d v

elo

city

, mA

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point 1 point 2 point 3 I=f(U)

Co

rona

cur

rent

, mA

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Voltage, kV

Ele

ctri

c w

ind

ve

loci

ty,

m/s

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0,6


Co

ron

a c

urr

en

t, m

A0

0,20,4

0,60,8

11,2

1,41,6

1,8

0 5 10 15 20 25

Voltage, kV

Ele

ctric

win

d ve

loci

ty, m

/s

0

0,05

0,1

0,15

0,2

0,25

0,3

0,35

0,4


Cor

ona

curr

ent,

Dn=0,03 m

Dn=0,04 m

Dn=0,05 m

Dependence of the maximum electric wind velocity and corona current on applied voltage, H=0,03 m


Electric wind in the pilot charging unit (I)

Schema of the measurement


Electric wind in the pilot charging unit (II)

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Voltage, kV

Co

ron

a c

urr

en

t, m

A

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Electric wind velocity I=f(U)E

lect

ric

win

d v

elo

city

, m/s

Dependence of the electric wind velocity and corona current on applied voltage in the pilot charging unit


Conclusions

• The electric wind velocity in the charging system needles in the nozzles increases with increase of the applied voltage.

• At distances H=Dn the electric wind velocity downstream the charging system is constant in the measurement points.

• The electric wind can change air velocity in the centre part of the flow downstream the nozzles.

• With increase of the distance from the charging unit the electric wind velocity decreases.

• The electric wind does not influence on the charged particle transport in the CAROLA collector at the distances H=3Dn.

investigation of electric wind in the corona charging unit of a novel electrostatic collector

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