Electrostatic precipitators for small-scale wood ... · PDF fileTechnologie- und...

Technologie- und Förderzentrumim Kompetenzzentrum für Nachwachsende Rohstoffe

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Hans Hartmann, Peter Turowski, Susanne Kiener

Technologie- und Förderzentrum im Kompetenzzentrum

für Nachwachsende Rohstoffe (TFZ), Straubing

Electrostatic precipitators for small-scale wood

combustion systems –

Results from lab- and field tests

IEA Task32-Workshop:

“Fine particulate emissions from small-scale biomass furnaces“

Central European Biomass Conference (CEBC), 26.-28.January 2011 in Graz


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Structure

• Overview on small-scale particle separators

• Field test with 3 ESP-types

• Results from test stand trials (4 ESP‘s)

• Summary and conclusions


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Overview on particle separator types for residential applications

Principle Advantage Disadvantage

Electrostatic

precipitator (ESP)

low pressure drop,

low cost

problems with organic

particles

Filtering separators

(e.g. baghouse filters)

good separation effect high pressure drop,

high technical efforts

Cyclone separators low cost low effect on fine particles

Scrubber flue gas condensation possible high technical efforts

medium separation effect

Flue gas condenation additional heat gain low separation effect

Catalyst effect on gases,

lower Corg load on particles

very low separation effect


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Configuration of ESP‘s

Chimney-top separators

Separators for flue gas tube integration

(living rooms)

Separators for central heating boilers

ESP-chimney systems


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Chimney-top ESP (1): Applied Plasma Physics (Norway)

Type: APP Residential ESP

Cleaning/maintennance from chimney top

effective length : ca. 1 m

High voltage; max. 33 kV

No active mechanical removal of PM deposits

Status: development

Photos:TFZ

part of precipitator

inside the chimney

high voltage electrode

part of precipitator

above the chimney

outlet

high voltage supply line

Gra

ph: A

PP


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Chimney-top ESP (2): OekoTube (by OekoSolve, Liechtenstein)

Type: Oekotube

no active removal of deposits

max 70 kW heat power output

Status: market available (only Switzerland)

Photos / Image: Oekosolve


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Weather protection

Isolation

Vibrator for

cleaning

Electronics

Mounting plate

High voltage

electrode

Ionisation zone

Inner tube

(springs)

Precipitation

zone

Chimney-top ESP (3): Ruff-Kat GmbH, Holzkirchen

Type: Ruff-Kat

Chimney mounted

Voltage: 20 kV

Mechanical removal of deposits (vibration)

Length: ca. 1 m above chimney opening

Status: Certified, field test

Separation surface (inner walls)

cleaned uncleaned

Photos / Image: Ruff-Kat


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Boiler attached ESP (1): Spanner SFF (by Fa. Spanner Re²)

Types: Spanner SFF 20 / SFF50 / SFF100

Mounted beside a boiler

Voltage: 15 kV

Mechanical removal of deposits (vibration)

With purge air cleaning of electrodes

Pressure drop: 40 pa

Status: Field tests

raw gas

clean gas

electrode

absorber

pipes

particle

container

pipe -cleaning

(vibration)4 depositing pipes with electrode casing

purge air cylinder

purge air cylinder

Werkbild : SpannerPhotos: TFZ


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Boiler attached ESP (2): Carola – Separator (by KIT, Karlsruhe)

Type: CAROLA (Develpment: Karlsruhe Institut of Technology)


Mechanical removal of deposits (rot. brush, 1 min/h)

Pressure drop: 10 pa

Voltage 16-18 kV

Tested with up to 30 kW

Status: development

Images: KIT


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Boiler attached ESP (3): AL-Top (by Schräder, Kamen)

Type: AL-Top,

ESP with infill of wetted metal

shavings as absobing surface


Status: development

clean

gas

metal shavings infill

(absorbing surface)

raw gas

high voltage

electrode

spray nozzle

injection

drain

outlet

Images: Schräder


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Integrated ESP (1): ”Airbox” by Spartherm Feuerungstechnik

Type: Airbox (for fireplace inserts),

Supplement exclusively for manufacturer ‘s furnaces (>15 kW)

Plate-type ESP, manuelly switched-on

Manual removal of PM deposits required after 100 h operation

Status: market-available

Photo / Images: Spartherm


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Integrated ESP (2): Zumikron (by Rüegg, Switzerland)

Type: Zumikron

Developed by Rüegg (Switzerland), built by: Kutzner+Weber

Mainly for single room heaters

Use of purge air for electrode cleaning

Manual removal of PM deposits required

Status: market-available (only Switzerland)

Photo / Images: Rüegg


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Water injection for cleaning the

inner tube of the chimney

Special isolation for fixing the


Chimney made of stainless steel

Electrode made of special

type of wire

Cleaning door

Special isolation and fixing the

high voltage electrode with a

spring

Outlet for cleaning water and

condensate

Temperature

sensor

High voltage

power supply

BoilerBoiler Neutralisa

tion box

with

pump for

cleaning

circuit

ESP-Chimney-type: Feinstaubkiller (by TH-Alternativ-Energie)

Type: “Feinstaubkiller“ (ESP-chimney)

Electrode over full length of chimney

Automatic periodic cleaning by rinsing with water

from surge tank

Particle removal as sludge deposit

Status: single built and single approval

Image: TH-Alternativ-EnergiePhotos: TFZ


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Procedure of field tests performed by TFZ

• Selection of 10 private households

• Assembling of filters and automatic data recording

(electricity consumption, operating hours)

• Instruction of users concerning documentation

• Continuous operation of ESP‘s during heating period 2008/2009

• Regular cleaning and observation by chimney sweep

• Collection of deposited ash from the chimneys and the ESP‘s over the

full period and

• Determination of fuel consumption


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ESP-types applied in field test (1)

APP Residential ESP,

example here: with chimney stove (6 kW)

Photos: TFZ


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K&W Zumik®on,

example here: with cooking stove (6 kW)


Photo: TFZPhoto: TFZ


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Spanner SFF 20

• example here: with log wood boiler, 15 kW

• mechanical cleaning was here activated

manually by press button


Photos: Ritt


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Observations from field tests

Observed failures/troubles:

short circuits

failure of electrode purge air supply

burn-out of fuses

display failure

breaking of electrode

fixation problems (at chimney top)

sensor defects

high voltage failure

chimney draft problems

rain water intrusion into chimney

counteraction of ESP-purge air with furnace air supply

noise harassment


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Results field tests: electrical power input

180

14113

47

28

0

40

80

120

160

200

Betrieb Standby-Betrieb

APP Residential ESP KW Zumikron Spanner SFF20e

lectr

ica

lp

ow

er

inpu

t W

operation stand-by


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Field test results: Calculated particle reduction

Partici-

pant

Furnace ESP-type Fuel Collected

particle massb)

Theoretical

reduction of

PM emissionc)

1 Chimney stove K&W Zumikronlog wood

(spruce, pine)0.18 kg 9 mg/m³

2 Chimney stove K&W Zumikronlog wood


4 a) Kitchen stove K&W Zumikronlog wood

(spruce, pine, beech)0.06 kg 5 mg/m³

5 Chimney stove APP Residential ESP log wood (beech) 0.30 kg 17 mg/m³

6 2 Chimney stoves APP Residential ESPlog wood


7 Tiled stove APP Residential ESPlog wood


8 Log wood boiler Spanner SFF 20log wood


9 Pellet boiler Spanner SFF 20 Wood pellets 0.15 kg 5 mg/m³

10 Wood chip boiler Spanner SFF 50 Wood chips 18.59 kg 158 mg/m³

a Only ash from connecting pipe and ESP because further furnaces were connected to the same chimneyb Particle mass in ESP + connecting pipe + chimneyc Calculated from fuel mass and specific flue gas volume, based at 13 % O2


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Field test results: Investigation of PAH-content in PM deposits

Materials with more than 50 ppm PAH are considered as cancerogeneous in

Germany

Above 1000 ppm they are considered as dangerous waste.

Participant 1 2 3 4 5 6 7 8 9 10

Furnacechimney

stove

chimney

stove

tiled

stove

kitchen

stove

chimney

stove

chimney

stove

tiled

stove

log wood

boiler

pellet

boiler

wood chip

boiler

Separator K & W K & W K & W K & W APP APP APP Spanner Spanner Spanner

Total PAH 183ppm 744ppm 1344ppm 922ppm 66ppm 470ppm 1713ppm 380ppm 21ppm 197ppm

PAH-contents of PM collected from connecting pipes + ESP + chimney


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• Selection of 2 suitable chimney stoves (a simple and a high value product)

• Tests with of 2 ESP‘s (Zumik®on and APP) at both stoves 4 test series

• Tests with Spanner SFF20 at log wood boiler (simple natural draft type)

• Test duration: 5 to 6 weeks per test series (typical operation)

• Weekly measurements of particle separation in raw and clean gas

(gravimetric determination)

• Additional trials with ESP-chimney type by “TH-Alternative Energie“

Trials performed at TFZ test laboratory


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Additional tests: ESP-chimney system by TH-Alternativ Energie

Photo: TFZImage: TH-Alternativ-Energie

Water injection for cleaning the

inner tube of the chimney

Special isolation for fixing the


Chimney made of stainless steel

Electrode made of special

type of wire

Cleaning door

Special isolation and fixing the

high voltage electrode with a

spring

Outlet for cleaning water and

condensate

Temperature

sensor

High voltage

power supply

BoilerBoiler Neutralisa

tion box

with

pump for

cleaning

circuit


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Test stand setup

Dilution ratio: 1 : 4 – 6

Diluted temperature:

< 52 °C

Gravimetric PM-

determination

Measuring over the

full batch

3 fuel batches

per trial


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Test stand results:

Zumikron ESP with simple-type chimney stove

0

9

2

18

20

- 15

19

70

- 45

8

10

7

- 5- 2

37

33

29

- 50

- 40

- 30

- 20

- 10

0

10

20

30

40

50

60

70

80

-500

-400

-300

-200

-100

0

100

200

300

400

500

600

700

800

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18

Test No

Raw gas

Clean gas

Separation

%mg/m³n

(13 % O2)

Mean separation: 11%

Separa

tio

n e

ffic

iency

Tota

l P

M e

mis

sio

n


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Test stand results : APPResidential ESP with simple-type chimney stove

51

48

54

69

79

88 8993

48

11

11

41

78

44

50

58

29

0

20

40

60

80

100

0

200

400

600

800

1.000

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18

Raw gas

Clean gas

Separation

%

Mean separation: 55 %

Tota

l P

M e

mis

sio

n

Separa

tio

n e

ffic

iency

Test No

mg/m³n

(13 % O2)


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Test stand results :

Spanner SFF 20 with log wood boiler (simple natural draft)

Operation without by-pass Operation with bypass

Mean separation: 25 and 80 %

11

- 41

- 89

37

66

40

69

80

50

86 96

61 55

94

88

- 100

- 80

- 60

- 40

- 20

0

20

40

60

80

100

-250

-200

-150

-100

-50

0

50

100

150

200

250

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15

Raw gas Clean gas

Separation

%mg/m³n

(13 % O2)

Tota

l P

M e

mis

sio

n

Separa

tion e

ffic

iency


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Test stand results :

TH Feinstaubkiller with log wood boiler (simple natural draft)

26

90 81

32

89

46

59

94

61

0

20

40

60

80

100

0

60

120

180

300

1 2 3 4 5 6 7 8 9

Raw gas

Clean gas

Separation

%

Mean separation: 64 %

mg/m³n

(13 % O2)

240

Tota

l P

M e

mis

sio

n

Separa

tio

n e

ffic

iency

Test No


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Summary and conclusions

• Three of four ESP‘s showed acceptable PM separations in both, field and

laboratory tests.

• An active mechanical cleaning of the deposited particles seems inevitable for

an undisturbed ESP-operation.

• Bevor market introduction the observed failures should be avoided reliably.

• An installation in living rooms is not accepted by the residents.

• Specific rules for handling and disposal of collected PM-mass need to be

elaborated due to the observed high PAH-contents.

• For determining the separation efficiency, a reliable and repeatable test

method needs to be elaborated.


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Thanks for listening !

Download of the complete research report

(in German language):

TFZ-report No. 23

www.tfz.bayern.de

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