Real-life emission of automatically stoked biomass boilers

Real-life emission of automatically stoked biomass boilers

Christoph Schmidl

Joachim Kelz, Franziska Klauser, Vijay Kumar-Verma, Manuel Schwabl, Markus Schwarz

Zürich, 14 June 2016

■ Biomass combustion technology has

improved tremendously:

■ FJ-BLT Wieselburg type testing

averages 2015/16 (n=26):

■ Efficiency = 96%

■ Carbon monoxide = 5mg/m³

■ Organic gaseous carbon < 1mg/m³

■ Total suspended particles = 7mg/m³

■ EN303-5 testing constant load

conditions

■ Limited information about field

performance

■ Beside particulates (PM10/2.5)

Benzo[a]pyrene (PAH) is critical


Introduction: General

(all emission results given at STP,13%O2)

Nanoparticle Conference 2016

Introduction: Particle size distribution of small-scale biomass combustion systems

Explanations: average particle size distribution of the BLPI measurements performed over the test runs;

data related to dry flue gas at STP and 13 vol. % O2; PE-m … modern pellet boiler; WC-m

… modern wood chip boiler; LW-m … modern logwood boiler; LW-o … old logwood boiler;

ST-m … modern stove; ST-o … old stove; TST-m … modern tiled stove

0

50

100

150

200

0,01 0,10 1,00 10,00

dp [µm ae.d.]

PM

[m

g/N

m³

/ d

log

(d

p)]

PE-m

WC-m

LW-m

LW-o

ST-m

ST-o

TST-m



■ Evaluate emissions (and efficiency) of biomass boilers

under laboratory conditions simulating real-life

operation

■ Investigate the operation performance of modern biomass

boilers in real installations in the field

■ Special focus particular Benzo[a]pyrene

■ Emissions of modern biomass boilers

■ Critical operation phases

■ Technology influence

■ Reduction measures


Objectives


■ Laboratory: Full Load, Part Load and

Load Cycle Test (8-hour Modulation)


Methodologies Study 1GB: 3

Sites

ES: 2

Sites GR: 1

Site

DE: 3

Sites

AT: 9

Sites

■ Field Measurements (n=73):

■ 18 Sites, 3 Building Types

(new, refurbished, old)

■ Continuous Efficiency

Monitoring over up to 3 years

■ Full Load Test in Field

■ Real Life Operation: 24h

Emission testing

circulation on

pump off

exhaust on

fan off

boiler on

off

reference cycle flow temperature / TVL return temperature / TRL

45°C

55°C

75°C

55°C

45°C

15

30

45

60

75

90

0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

100%

tem

pe

ratu

re [°

C]

no

min

al b

oil

er lo

ad [%

]

time

8h

t1 t2t0 t3 t4 t5

8h

measurements


Results Study 1: Field measurements

■ What’s the real boiler operation behavior?

■ Boiler operation behavior depends on

■ boiler type

■ weather

■ building

■ user habits


0

20

40

60

80

100

00:00:00 06:00:00 12:00:00 18:00:00 00:00:00

bo

iler

po

wer

[%]

time

AT3-3

0

20

40

60

80

100

00:00:00 06:00:00 12:00:00 18:00:00 00:00:00

bo

iler

po

wer

[%

]

time

AT3-4

0

20

40

60

80

100

00:00:00 06:00:00 12:00:00 18:00:00 00:00:00

bo

iler

po

wer

[%

]

time

AT7-2


Example from 24h field emission measurement


0

100

200

300

400

500

600

700

800

900

1000

0

5

10

15

20

25

30

35

40

45

50

08:00 09:00 10:00 11:00 12:00 13:00 14:00 15:00 16:00 17:00

emis

sio

ns

[pp

m]

oxy

gen

[v%

] P

M [

mg/

m³]

oxygen [v%] particulate matter [mg/m³] carbon monoxide [ppm]

nitrogen oxides [ppm] organic compounds [ppm]


■ Emission factors of pellet boiler in modulating operation.

■ All top feed burner

■ Wide modulation range

0

10

20

30

40

50

60

70

80

90

100

Avg. 72,7 [%]

Annual LOT15efficiency

0

10

20

30

40

50

60

70

80

90

100

Avg. 75,5 [%]

LOT15.efficiency

Overview: Field Performance of Pellet Boilers


0

200

400

600

800

1000

1200

1400

Avg. 417,7 [mg/m³ (STP)]

CO

0

50

100

150

200

250

Avg. 138,8 [mg/m³ (STP)]

NOx

0

10

20

30

40

50

60

70

80

90

100

Avg. 10,0 [mg/m³ (STP)]

OGC

0

10

20

30

40

50

60

70

80

90

100

Avg. 26,2 [mg/m³ (STP)]

TSP

0

10

20

30

40

50

60

70

80

90

100

Avg. 78,0 [%]

efficiency


Field performance: Pellet Boilers 10-26kW

■ Improvement of boiler technology is evident

■ Narrow distributions very stable performance even in

full day measurements


0

10

20

30

40

50

60

70

80

90

100

avg: 21,3 mg/m³n: 10

avg: 24,8 mg/m³n: 11

avg: 32,0 mg/m³n: 11

full load part load full day

tota

l su

spen

ded

par

ticl

es m

g/m

³

Older Boiler Model (10-26kW)

0

10

20

30

40

50

60

70

80

90

100

avg: 13,2 mg/m³n: 10

avg: 17,2 mg/m³n: 10

avg: 18,0 mg/m³n: 9


tota

l su

spen

ded

par

ticl

es m

g/m

³

New Boiler Model (10-26kW)


Field performance: Pellet Boilers 6-12kW

■ Mean/Median emissions quite satisfying, but

■ higher variability of emissions compared to bigger boilers

■ Part load operation (30%) difficult for small boiler (6kW)


0

10

20

30

40

50

60

70

80

90

100

avg: 29,8 mg/m³n: 10

avg: 38,9 mg/m³n: 10

avg: 39,0 mg/m³n: 9


tota

l su

spen

ded

par

ticl

es m

g/m

³

Small Boiler (6kW)

0

10

20

30

40

50

60

70

80

90

100

avg: 22,5 mg/m³n: 13

avg: 24,1 mg/m³n: 12

avg: 24,8 mg/m³n: 14


tota

l su

spen

ded

par

ticl

es m

g/m

³

Compact Boiler (12kW)


Methodology Study 2: Dilution Sampling for TSP and BaP

■ Sampling:

■ Start/Stop/Nominal-/Part-Load

■ Dilution method (ISO 11338-1)

■ Dilution ratio: 1:10

■ Filter T <40°C

■ Isokinetic sampling at steady state operation

■ Storage/Transport: sealed filter or solution; T < 0°C

■ Analysis:

■ Adapted to DIN EN 15549:2008 and VDI 3874

■ Diluted in cyclohexane and dichlormethane

■ Analysis with GC-MS (Quadrupole – mass spectrometer)



Study 2: TSP/BaP – Tested Technologies

Power [kW] Fuel Principle of combustion

A 15

Spruce pelletsA1 quality

EN14961-2

topfed burner

B 15

horizontally fed burner

C 70

D 500

E 12

underfed burnerF 15

G 500 Wood chips W20 horizontally fed burner




Particle Emissions: Combustion Phases


n = 15 9 10 9

start stop part load full load

n = 15 9 10 9

start stop part load full load

Log scale

The emissions during start and stop are 1 to 2 orders of magnitude

higher than during continuous operation



BaP Emissions – Operation PhasesL

ine

ar

Sc

ale

Lo

g S

ca

le

n= 15 9 10 9

start stop part.load full load start stop part.load full load

n= 15 9 10 9

Ba

P [n

g/m

3S

TP,d

ry 1

3%

O2

]

Ba

P [n

g/m

3S

TP,d

ry 1

3%

O2]



Correlation other parameters (Examples)

Only useful correlation with EC

BaP - CO

00

BaP – EC (Elemental Carbon)

CO

[mg

/m3

ST

P,d

ry 1

3%

O2

]

EC

[µg

/m3

ST

P,d

ry 1

3%

O2

]BaP [ng/m3STP,dry 13% O2]BaP [ng/m3STP,dry 13% O2]

00

top

fed

Horizontally

fed

top

fed

Horizontally

fed

Under

-fed

un

de

rfed



BaP Emissions - Technology ImpactL

ine

ar

Sc

ale

Similar median values for different systems but...

Lowest values observed for topfed systems

Trend: higher risk of outliers with underfed systems

Ba

P[n

g/m

3S

TP,d

ry 1

3%

O2

]

Lo

g S

ca

le

Comparison with Literature

■ Best-case scenarioBest Caseoperation

Worst Caseoperation

modern „traditional“

Automatic boilers Logwood heatings

1x Start and Stop, 8 h full load

Start-Stop-operation

Primary and secondary air supply

(Ozgen et al., 2014)(Kelz et al., 2012)

(Kelz et al., 2012)(Orasche et al., 2012)


BaP

[ng/m

3S

TP,d

ry 1

3%

O2

]

best worst modern trad.

LW LW

105

104

103

102

101

105

104

103

102

101



Comparison with Literature

■ Best-case scenarioBest Caseoperation

Worst Caseoperation

modern „traditional“

Automatic boilers Logwood stoves

1x Start and Stop, 8 h full load

Start-Stop-operation

Primary and secondary air supply(Ozgen et al., 2014)(Kelz et al., 2012)

(Kelz et al., 2012)(Orasche et al., 2012)

BaP

[ng/m

3S

TP,d

ry 1

3%

O2

]

best worst modern trad.

stove

stove

105

104

103

102

101

n= 7 7 6 4


Summary

■ In general the tested biomass boilers peformed widely well

under field conditions

■ Higher variability of particle emission from smaller boilers

■ Load cycle test is suitable to predict real-life performance

■ Instationary phases of combustion (start / stop) are critical

in terms of particle and BaP emissions

■ Underfed combustion technology seems to have higher

risk of incomplete combustion in these phases

■ BaP emissions are lower for boilers compared to stoves

but not neglibile when start/stop phases occur frequently



Conclusions

■ Difference between lab and field performance of

biomass boilers is evident, but widely is in an acceptable

range (for the tested technologies)

■ Real-life oriented test methods could trigger further

development of already mature technology

■ Further reduction of particle emissions is possible:

– By appropriate design and control concept of the

heating system to reduce start- / stop-phases

– Optimisation of combustion conditions in start- and

stop-phases



We would like to thank all company partners having contributed

to the research for their valuable support.

The research leading to these results has received funding from the European

Union Seventh Framework Programme (FP7/2007-2013) under Grant

Agreement n° 268217

and the Austrian COMET Research Programme.


Acknowledgements


Christoph SchmidlBIOENERGY 2020+ [email protected]

+ 43 7416 52238-24


Thank you for your kind attention!

Supplemental Material

Comparison Load Cycle – Real Life Performance

Pellet Boiler 1

Pellet Boiler 2

Pellet Boiler 3

Parameter UnitLoad cycle

Real lifeLoad cycle

Real lifeLoad cycle

Real life

CO [mg/m3STP] 272 343 434 358 415 447

NOx [mg/m3STP] 110 135 158 151 128 120

OGC [mg/m3STP] 9 7 24 7 3 5

Dust [mg/m3STP] 37 25 30 32 27 18

Efficiency % 78,2 75 75,2 83,6 81,1 83,2

Annual Efficiency

% - 72,4 - 78,8 - 81,4





Technology Influence – Nominal/Part Load



Technology Influence – Start/Stop Phases

Boiler operation hours

13.06.16


0

500

1000

1500

2000

2500

3000

ann

ual

fu

ll lo

ad h

ou

rs [

h/a

]

BW 10 BW 26 BW 10 EP BW 26 EP BW2 10 BW2 21

VW 6 IAT VW 6 V VW 12 DDA VW 12 H/P VW 12 H/P IAT EW 19

0

1000

2000

3000

4000

5000

6000

7000

ann

ual

bo

iler

op

erat

ing

ho

urs

[h

/a]



Boiler starts

13.06.16


0

500

1000

1500

2000

2500

3000

3500

ann

ual

nu

mb

er o

f b

oile

r st

arts

[-]



Example: 24h Field emission measurement


0

100

200

300

400

500

600

700

800

900

1000

0

10

20

30

40

50

60

70

80

90

100

18:00 21:00 00:00 03:00 06:00 09:00 12:00 15:00 18:00

emis

sio

ns

[pp

m]

load

[%

], o

xyge

n [

v%]

PM

[m

g/m

³]

boiler load [%] oxygen [v%] particulate matter [mg/m³]

carbon monoxide [ppm] nitrogen oxides [ppm] organic compounds [ppm]


Methodology BaP: Sampling periods

From: Until:

Start: Start of the ignition system CO- & Temp- criteria are fulfilled (100ppm + Cofull load) &

(90% from Tfull load)

Stop Decreasing fuel load indicated by increasing CO-conc

Air fan (air supply) stops.

Full load At least 1 hr at steady conditions

Partial load At least 1 hr at steady conditions, 30 % of nominal load


start

T (comb. Chamber)

[°C]

CO [ppm]

Flow rate (flue gas)

[m3/h]

O2 [%]

CO2 [%]

T flue gas [°C]

stop

T (comb. Chamber) [°C]

CO [ppm]

Flow rate (prim. air)

[m3/h]

Flow rate (sec. air)

[m3/h]

CO2 [%]

T flue gas [°C]


Date post:	09-Apr-2022
Category:	Documents
Upload:	others
View:	3 times
Download:	0 times

Real-life emission of automatically stoked biomass boilers

Documents