Rotary kiln pyrolysis- First results of a 3 MW pilot plant

Rotary kiln pyrolysis- First results of a 3 MW pilot plant

Michael Halwachs

4th International Freiberg Conference on IGCC & XtL Technologies

3-5 May 2010 Dresden, Germany

04.05.2010

Rotary kiln pyrolysis - First results of a 3 MW pilot plant Michael Halwachs

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Overview

• About the project

• Balance of the

pyrolysis pilot plant

• Results

• Outlook

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About the Project

Usage of agricultural residues (straw) for power generation is a widely unexplored source of energyCheap feedstockregional available in huge amounts

Fundamental idea: Co-firing of straw in an existing coal fired power station

Problem: high content of Chlorine (Cl) and Potassium (K) of the straw is harmful for boiler and heat exchanger of the power station

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About the Project

Troubleshooting:

Split up of the biomass into a volatile fraction that can be used for co-firing and a char fraction by a pyrolysis process.

The undesired components (Cl, K, Na) should be concentrated in the char fraction.

Pyrolysis-pilot plant DürnrohrJacked rotary kiln reactor (3 MWth)

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Kohlekraftwerk Dürnrohr

•Austria’s biggest coal fired power plant

•built as a replacement for the Zwentendorf nuclear power station, a plant that was finished but due to a 1978 referendum never started up

•consists of two blocks electrical output of 405 MW (operated by Verbund Austrian Thermal Power AG) and electrical output of 352 MW operated by the Energie-Versorgung Niederösterreich (EVN) AG

•The plant is powered by black coal imported from the Czech Republic and Poland but it can also use natural gas as a fuel

•In 2004 a heating plant (largest such in Austria, at the time) using the dissipated waste heat was opened

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About the project

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Flowsheet

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Operating figures

Fuel power of the rotary kiln reactor: 3 MW

Throughput of straw: ca. 600 to 800 kg/h

Pyrolysis temperature range: 450 – 630 °C

Residence time of the feedstock: 30 – 45 min

Pyrolysis gas characteristics

Content of pyrolysis oil (gravimetric): 40 – 200 g/Nm³

Content of pyrolysis oil (GC-MS): 30 – 100 g/Nm³

Dust and entrained char: 20 – 120 mg/Nm³

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Feedstock

Wheat straw (indoor stored)Wheat straw (field stored)Maize strawStraw pelletsSorghum strawReed strawPalm nut shellsMiscanthus strawActiprot

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Fuel SamplesS

traw

Pel

lets

Ree

d S

traw

Sor

ghum

Stra

w

Whe

atS

traw

Pal

mnu

tShe

lls

Mis

cant

hus

Stra

w

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Pyrolysis Char SamplesS

traw

Pel

lets

Whe

atS

traw

Sor

ghum

Stra

w

Ree

d S

traw

Pal

mnu

tShe

lls

Mis

cant

hus

Stra

w

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Balance of the plant

• Creating a model of the system• Process simulation tool IPSEpro (stationary

equation oriented flow sheet simulation)• Validation of measured data

Property Libraries (DLLs)

C-Programming IDE

Fig.: Structure of IPSEpro (SimTech, 2001)

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Part of the testing scheme

Straw

Variation of the pyrolysis temperature

Variation of the residence time

Actiprot

Variation of the pyrolysis temperature

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Straw

Fig.: Mass- and energy fractions of the pyrolysis products of straw controlled by the pyrolysis temperature

0

10

20

30

40

50

60

70

80

90

100

450 500 550 600

pyrolysis temperature [°C]

mass fraction [%

]

0

10

20

30

40

50

60

70

80

90

100

450 500 550 600


energy fraction [%]

char

pyrolysis oil

pyrolysis gas

char

pyrolysis oil

pyrolysis gas

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Actiprot

Fig.: Mass- and energy fractions of the pyrolysis products of Actiprot controlled by the pyrolysis temperature

0

10

20

30

40

50

60

70

80

90

100

450 500 550


mass fraction [%

]

0

10

20

30

40

50

60

70

80

90

100

450 500 550

pyrolysis temperature [°C]enrgy fraction [%

]

char

pyrolysis oil

pyrolysis gas

char

pyrolysis oil

pyrolysis gas

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0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

100%

C H O N S Cl K

Elements

Separation in char, gas and oil

pyrolysis oil

pyrolysis gas

char

Separation of the chemical elements

Fig.: Separation of the chemical elements in pyrolysis gas, pyrolysis oil and char for a pyrolysis operation of indoor stored straw.

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Efficiency

• Chemical efficiency

0.0

0.2

0.4

0.6

0.8

1.0

450 500 550 600


chem

ical efficiency [1]

straw acti‐prot

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Efficiency

Sankey-diagram for straw pyrolysis for the case of energy supply by pyrolysis gas, energy flows [kW]

Efficiency

Pyrolysis process 0.48

Coal fired power station Dürnrohr

0.42

Generated electricity by straw

0.2

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Conclusions

The process works technically correct

The gaseous product is suitable for co-firing in a coal fired power plant

The undesired components (Cl, K) are concentrated in the char fraction

• Efficiency is significantly higher than the electrical efficiency of smaller biomass fired power stations or CHP systems.

Approximately 50 % of the energy in the feedstock can be provided for co-firingFurther investigations on usage of “biochar”More Fuels (e.g. sewage sludge, residues from agricultural and paper industry)

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Outlook

• Connection of the pyrolysis process to the coal fired power plant.

Scenario 1: 1 x 30 MW (one rotary kiln reactor)Scenario 2: 3 x 30 MW (three rotary kiln reactors)

Fig.: Scenario 1

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End

Documents

Rotary kiln pyrolysis- First results of a 3 MW pilot plant