Jerzy Mizeraczyk

XII INTERNATIONAL CONFERENCEXII INTERNATIONAL CONFERENCEONON

ELECTROSTATIC PRECIPITATIONELECTROSTATIC PRECIPITATION

NuernbergNuernberg

May 9 – 13, 2011May 9 – 13, 2011

CeCentre for Plasma and Laser Engineeringntre for Plasma and Laser EngineeringThe Szewalski Institute of FluidThe Szewalski Institute of Fluid--Flow MachineryFlow Machinery

Polish Academy of SciencesPolish Academy of SciencesGdańsk, PolandGdańsk, Poland

PIV MEASUREMENTSPIV MEASUREMENTS

OF ELECTROHYDRODYNAMIC FLOW IN ESPsOF ELECTROHYDRODYNAMIC FLOW IN ESPs

MotivationMotivation of laser investigations of flow patterns of laser investigations of flow patternsin in electrostatic precipitatorelectrostatic precipitatorss

Interest in improving electrostatic precipitator (ESP) collection of fine particles (micron and submicron sizes).

How does the EHD flow caused by the presence of electric field and charge in ESPs influence the particle precipitation process?

2

OUTLINEOUTLINE

Laser flow visualization • Principles of laser flow visualization

Particle Image Velocimetry (PIV)• Principles of of 2-dimensional (2D) and 3-dimensional (3D) Particle Image Velocimetry• Products of PIV (flow velocity field, flow streamlines, vorticity map) Example of PIV measurements in a spike-to-plate electrostatic precipitator (ESP):• PIV measurement of the dust particle flow structures•Structures of the dust particle deposits• Correlation between the dust particle flow structures and the dust particle deposit structures

Conclusions

3

PRINCIPLEPRINCIPLEOF PARTICLE IMAGE VELOCIMETRY (PIV)OF PARTICLE IMAGE VELOCIMETRY (PIV)

  

•Flow seeded with particles following the motion of the flow 

•Light source for illumination of the flow 

•Camera to capture 2 images of the motion of the seed particles

v = S / (t2 – t1)4

2 consecutive CCD images

2D PARTICLE IMAGE VELOCIMETRY - PRINCIPLE 2D PARTICLE IMAGE VELOCIMETRY - PRINCIPLE

5

EXPERIMENTAL SETUP FOR 2D PIV MEASUREMENTS EXPERIMENTAL SETUP FOR 2D PIV MEASUREMENTS

The standard PIV equipment (Dantec PIV 1100):

-        a twin second harmonic Nd-YAG laser system capable of changing t = t2 – t1

-        cylindrical telescope to produce a laser beam sheet-    CCD camera, tmin = 2 s,

1018x1018 pixels-        image processor-        PC computer 6

7

EXPERIMENTAL SETUP FOR 3D PIV MEASUREMENTSEXPERIMENTAL SETUP FOR 3D PIV MEASUREMENTS

8

Products of PIV (flow velocity field, flow streamlines, vorticity map)Products of PIV (flow velocity field, flow streamlines, vorticity map)

Time-averaged flow streamlines in the ESP

Vp = 0.9 m/sFlow streamlines not much disturbed in

comparison with no voltage flow streamlines. Some disturbances near the plate electrodes in the discharge region.

Vp = 0.6 m/sStronger disturbances than for the Vp=0.9 m/s,

vortices in the discharge region.

Vp = 0.2 m/sStrong vortices in the discharge region. Pair of

vortices placed 100 mm dowstream the wire electrode block the flow in the ESP duct centre.

Laser flow visualization and PIV - exampleLaser flow visualization and PIV - exampleStudy of the dust particle flow structures in a wire-plate ESP – laboratoryStudy of the dust particle flow structures in a wire-plate ESP – laboratory

9

Flow velocity field in the ESP model at a main flow velocity of 0.6 m/s. Positive polarity, voltage 24 kV.

10

LASER FLOW VISUALIZATION AND LASER FLOW VISUALIZATION AND PIVPIV IN ESP IN ESP

Study of the dust particle flow structures in 7-electrode wire ESP - laboratory

11

Primary flow velocity: 0.6 m/s (Reynolds number 4000)

Flow gas: ambient air Dust: TiO2 particles (2D PIV) or cigarette smoke (3D PIV)

Operating voltage: 0 – 28 kV (positive polarity)

Discharge current: 0 – 210 A (Ehd number up to 3 * 108)

Spike electrode:12 spikes200 mm long

1 mm thickness

14 measurement planes:

A, B, C - longitudinal

E - N - transverse

EHD FLOW PATTERNS IN A SPIKE-PLATEEHD FLOW PATTERNS IN A SPIKE-PLATE ESP ESPUNDER POSITIVE AND NEGATIVE POLARITIES  UNDER POSITIVE AND NEGATIVE POLARITIES  

Side view

V [m/s]

12

EHD FLOW PATTERNS IN A WIDE SPACINGEHD FLOW PATTERNS IN A WIDE SPACING SPIKE-PLATESPIKE-PLATE ESP ESPUNDER POSITIVE AND NEGATIVE POLARITIES  UNDER POSITIVE AND NEGATIVE POLARITIES  

IMAGE OF THE PRECIPITATED DUST

Dust

13

EHD FLOW PATTERNS IN A SPIKE-PLATEEHD FLOW PATTERNS IN A SPIKE-PLATE ESP ESPUNDER NEGATIVE POLARITUNDER NEGATIVE POLARITYY    

FLOW PATTERN AND IMAGE OF THE PRECIPITATED DUST

14

U = -27.4 kVI = 260 A

Plane A

Dust

EHD FLOW PATTERNS IN A SPIKE-PLATEEHD FLOW PATTERNS IN A SPIKE-PLATE ESP ESPUNDER NEGATIVE POLARITUNDER NEGATIVE POLARITYY    

15

3D PIV MEASUREMENT OF VELOCITY X-COMPONENT

EHD FLOW PATTERNS IN A SPIKE-PLATEEHD FLOW PATTERNS IN A SPIKE-PLATE ESP ESPUNDER POSITIVE POLARITUNDER POSITIVE POLARITYY  

Side view

16

V [m/s]

Front view

NARROW ESP WITH LONGITUDINAL WIRE ELECTRODENARROW ESP WITH LONGITUDINAL WIRE ELECTRODE

X in mm

• Air flow generated by DC corona discharge

• Electrode configuration determines the flow direction

• Flow velocity up to 1 m/s

• Flow rate up to 630 cm3/s

EHD gas pump features:Velocity profiles at the exit section of EHD gas pump

Velocity profile at the exit of EHD gas pump (3D PIV)

EHD gas pump overviewFlow generated by EHD gas pump

PIV measurement

EHD GAS PUMPEHD GAS PUMP

17

Length of HV and grounded electrodes: 50 mmLength of floating interelectrodes: 45 mmHigh voltage electrodes width: 15 mmHV and FL interelectrodes in optimum position

Floating interelectrodes width: 3 mmFloating to grounded electrode distance: 6 mm Grounded electrodes width: 3 mm Grounded to floating electrode distance: 13 mm

Dielectric: glass plate – 2 mm thick High voltage: Upp = 32 kV, f = 1.5 kHz

Airflow velocity m/s

Time-averaged streamlines of a airflow inducedby multi DBD actuator with floating saw-like interelectrodes

18

EXPERIMENT - CALCULATIONEXPERIMENT - CALCULATIONFlow patterns in wire-plate ESP for various dust densities

Experiment Calculation – K. Adamiak & P. Atten

19

Flow patterns in wire-plate ESP for various Ehd/Re2 ratio

Calculation – Chun & ChangExperiment

Ehd / Re2 – a measure of the EHD disturbance of the primary flow

Ehd = I t * L3 / (A * * g2 * i) Re = U0 * L / g

EXPERIMENT - CALCULATIONEXPERIMENT - CALCULATION

20

LASER FLOW VISUALIZATION IN INDUSTRIAL ESPLASER FLOW VISUALIZATION IN INDUSTRIAL ESP

21

LASER SYSTEM FOR FLOW VISUALIZATION LASER SYSTEM FOR FLOW VISUALIZATION ON THE TOP OF INDUSTRIAL ESPON THE TOP OF INDUSTRIAL ESP

22

All four sections ON, hammering at t = 0 in section 4

LASER FLOW VISUALIZATION IN INDUSTRIAL ESPLASER FLOW VISUALIZATION IN INDUSTRIAL ESP

Light-green spots – dust in the ESPYellow lines – flow streamlinesdeduced from the flow images

23

CONCLUSIONSCONCLUSIONS

24

Laser visualization and Particle Image Velocimetry proved to be useful instruments in studying flow and collection phenomena in electrostatic precipitators

Owing to the PIV measurement a correlation between structures of the particle flow and particle deposit in the spike-plate ESP was found. The particle flow structures explain how the particle deposit structures are formed.

Basing on the PIV results we found a correlation between the particle flow structures and the total collection efficiency for the various configurations of spike-type electrode. Negative effect for downstream-directed one-sided electrode.

Centre for Plasma and Laser EngineeringInstitute of Fluid Flow Machinery

Polish Academy of Sciences, Gdańsk, PolandJ. Mizeraczyk, J. Podliński, M. Kocik, M. Dors, J. Dekowski, A. Niewulis

COLLABORATORSCOLLABORATORS

Department of Electrical and Electronic EngineeringOita University, Japan

T. Ohkubo, Y. Nomoto, S. Kanazawa

Department of Engineering Physics McMaster University, Hamilton, Ontario, Canada

J.-S. Chang, D. Brocilo, K. Urashima, Y.N. Chun, A.A. Berezin

Laboratoire d'Electrostatique et de Matériaux DiélectriquesUniversité Joseph Fourier, Grenoble, France

P. Atten

Laboratoire d’Etudes AérodynamiquesUniversité de Poitiers, France

G. Touchard

Department of Ecological EngineeringToyohashi University of Technology, Japan

A. Mizuno

25