measuring the performance of biomass

8/18/2019 Measuring the performance of biomass

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Measuring the performance of biomass

small scale gasification plants by

implementing mass and energy balances

S. Vakalis, D. Prando,F. Patuzzi and M. Baratieri

1Graz - 17.01.2014


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I. Introduction and general information

II. The „GAST‟ project

III. On-site measurements

IV. Mass and energy balances

V. Discussion of results

VI. Conclusion

Measuring the performance of biomass small scale gasification plants by implementing mass and energy balances 2

I II III IV V VI

Contents


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The concept of gasification

• Thermal process

• Sub-stoichiometric oxygen

• “Packs” energy into chemical bonds

• Mainly gaseous products


I II III IV V VI

Pyrolysis Gasification Combustion

Increasing Oxygen


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I II III IV V VI

Small scale biomass gasification

Small scale applications

200 kWe 1 MWe

Gasifier (ICE or GMT)

Boilers

Stirling

Downdraft

Updraft

ORC

Fluidized Bed


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I II III IV V VI

Small scale gasification – downdraft

Evaporation of moisture

Decomposition

Combustible gases

Gasification reactions

Biomass

Bio-oil

Char

Gases

Combustion

Products

Producer gas

(tar)

….

Char / ash


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I II III IV V VI

The „GAST‟ project

Funded by the Autonomous

Province of South Tyrol

Small scale biomassgasification plants

Scope

Monitoring and assessment Optimization of performance

Environmental control

Project partners


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The „GAST‟ stats


I II III IV V VI

60

21

14

authorized

projects

operating

Gasifier Fuel Size Type

A tech. WoodChips

45 kWe

120 kWthJoos

B tech. Wood

Chips

135 kWe

230 kWth

Char

Bed

C tech. Pellets180 kWe

270 kWth

Rising

CC

Monitoring campaignOverall numbers


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I II III IV V VI

Process chain

‘Raccomandazione CTI 13’ was followed

(Italian committee of thermotechnical engineers)

Gasification power plant (A tech.)

AIRGASIFIER(ER≈0.3)

DRYFILTER

HEATEXCHANGER

ICEWOOD

CHIPS

Pel: 45 kWel (nominal data)

Pth: 120 kWth

CHAR

TAR

Pth- syngascooling

Pth- water/oil

cooling

- exhausts

cooling

Pel

gas-tar

sampling

gas-tar

sampling


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I II III IV V VI

Biomass characterization

Sampling UNI EN 14778

C, H, O UNI EN 15104

Humidity UNI EN 14774‐3

Ash UNI EN 14775

Volatiles UNI EN 15148

HHV / LHV UNI EN 14918LHV ~ 18 MJ / kg (lower heating value)

Exch ~ 20 MJ/ kg (chemical exergy)

45,580

%

5,795%

41,023

%

,080%,350%

7,011%

C H O N Ash Moisture

Wood Chips


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I II III IV V VI

Gas composition

• Mobile micro- GC unit

• Columns: PLOT-U, MOLSIEVE

CO

21,8%CO2

7,8%

H217,1%

N2

51,7%

CH41,6%

Filtered gas composition


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I II III IV V VI

Gas composition


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I II III IV V VI

Char analysis

C, H, O UNI EN 15104

HumidityUNI EN 14774‐3

Ash UNI EN 14775

HHV / LHV UNI EN 14918LHV ≈ 23 MJ/kg (on dry basis)

mCHAR /mBIOM ≈ 2 %


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I II III IV V VI

Tar sampling

UNI CEN TS 15439

Heated probe for sampling

Sampling bottles (isopropanol 99%)

Temperatures : + 40, -20

Micro GC

sampling bottles


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Tar analysis

0,1

1,0

10,0

100,0

1000,0

10000,0

Tar production (ng)

Uni Bz particolato ng/assoluti

Preliminar results on PAH compounds

GC-MS technique

- separation DB5 MS

column (J&WScientific)

- detection high

resolution (R>10.000)

mass spectrometer

(GC-HRMS,

MAT95XL, Thermo

Scientific).- addition of deuterated

internal standards.


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I II III IV V VI

Measuring mass

fuel fuel fuel P m LHV

A critical aspect of the balance of plant

Measurement of mass [kg] and not volume [m ]

• Bulk density of wood chips is

not a constant parameter

• Volume of gas has significantvariations due to fluctuating

conditions (T, P) and fugacity

3


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I II III IV V VI

Mass balance


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Measuring energy

Electricity was measured directly from the meter

HeatΔTemp and V of water

Thermocouple (type T)

Transit-time ultrasonic flow meter

.

PT = Pe + Pth


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I II III IV V VI

Energy Fluxes

-8,75 energy demand of auxilaries (nominal data)

input

198

electricity 42.8

heat 98

losses 57.2

electricity 42.8 KW

Fluxes (kW)

Distribution

losses

29%

kWe

22 %2%

kWth50 %

Char

198 kW (100%)

4% 46%

losses 39

input

159

need of implementation of further measurements


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I II III IV V VI

Exergy Fluxes

Input

221

air

Electricity 42.8

Physical exergy (heat) 20.8

Chem.exergy

(char, tar)losses

Output gasifier

Total exergy

Exergy Flow (kW)

Measure of the maximum amount of work that can theoretically be

exchanged by a system in thermodynamic equilibrium with its

surroundings through a ideal (reversible) process.

[Ex = h - ho - To ( s – so)]

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I II III IV V VI

Energy and Exergy Balances

For an input of 40 kg per hour of wood chips (18 MJ /kg)

• electricity 42.8 kW

•heat 98 kW

• overall energy efficiency ~ 72 %

• net electric efficiency ~ 22%

• exergy efficiency (gasifier) ~ 63%


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I II III IV V VI

Conclusions

• Rapid development of small scale biomass gasifiers in

South Tyrol

– incentives, CO2 neutral, extensive biomass utilization in the area

• Gasifiers optimized for specific input parameters

– also: operating conditions, size

• Exergy is useful when the scope is production of work

– but cogeneration plants have also other product streams

• High T tar cracking

– but increased heat transfer and exergy losses


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I II III IV V VI

Outlook

• Complete the monitoring campaign

– apply the same procedure to the other plants (B, C)

• Compare different technologies

– on the basis of energy balance

– on the basis of exergy balance

– looking at the heat transfer performance

• Calibrate models

– b.o.p., with enhanced thermodynamic (multi stage, “multi box”)


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Thank you for the attention!

Danke für Ihre Aufmerksamkeit!

S. Vakalis, D. Prando,

F. Patuzzi and M. Baratieri

24Graz - 17.01.2014

measuring the performance of biomass

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