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TU Bergakademie Freiberg I Department of Energy Process Engineering and Chemical EngineeringGerman Center of Energy Ressources I Fuchsmühlenweg 9 I 09596 Freiberg, Germany I phone +49(0)3731/39 4498

fax +49(0)3731/39 4555 I mail [email protected] I web www.energierohstoffzentrum.de

Department of Energy Process Engineeringand Chemical Engineering

Pyrolysis behaviour of brown coal in a pressuriseddrop tube reactor

Denise Reichel, Stephan Siegl, Kevin Günther, Steffen Krzack, Bernd Meyer

5th International Freiberg Conference on IGCC & XtL Technologies ‐ IFC2012

21st – 24th May 2012 – Leipzig, Germany

Session 10‐1

5th International Freiberg Conference on IGCC & XtL Technologies 21.-24. May 2012 in Leipzig, Germany

I. Background & motivation

II. Experimental setup & investigations

III. Results Residence time

Pressure Influence on product yields and composition

Kinetic parameters for gas yields

IV. Future Prospects

2

Outline

5th International Freiberg Conference on IGCC & XtL Technologies 21.-24. May 2012 in Leipzig, Germany 3

I. Background & motivation

Thermochemical conversion behaviour of coal

EXPERIMENTS on coal behaviour during thermochemical conversion are a necessarystep for better understanding and simulation of thermochemical processes as well as

for an efficient use of energy sources.

• Gasification

• Pyrolysis

• Hydrogenation

• Combustion

Thermochemical processes

• Gasification

• Pyrolysis

• Hydrogenation

For Germany:

Focus on processesfor non‐energeticuse of coal

Thermochemical conversionbehaviour

• Process simulation as tool forprediction of conversionbehaviour

• Consistent data necessary forimplementation and validationof process models

Knowledge necessary for

• Technology development

• Optimisation

• Dimensioning of

these processes

• Exceptional position of pyrolysis

• a complex processmultitude of parallel reactionspartly dependant on each other

• Various influencing parameters (feedstock, process)

• Less data available for pressure influence

Pyrolysis


II. Experimental setup and investigations

Pressurised drop tube reactor

4

Coal feeding

Coalparticle

Partiallypyrolysedparticle

Coke particle

Electricalfurnace

Argon feeding

Argon feedingElectric traceheating

Pyrolysis gas + argon

Coke collectorwith electrictrace heating

Reactor tubePyrolysis gas

FeedsCoal / biomassParticle size: 40…500 µmMoisture: < 10 wt.%Feed rate: up to 10 g/min

EquipmentHeated lenght: 1,100 mmReactor ID: 20 mm3‐stage condensing system(‐20 °C ethylene glycol/H2O)Online micro GC

Process conditionsTemperature: ≤ 800 °CPressure: ≤ 30 bar (g)Gas atmosphere: ArgonVolume flow rate argon:≤ 130 l/h (STP)



Experimental procedureFeedstock

Drying (105 °C)

Grinding / Sieving

Pre‐drying (70 °C)

Pyrolysis in drop tube

40…100 µm

Material balance, char properties, kinetics

charliquid product (+THF) gas

tar/oil

Distillation

THF + water

analysis

analysis

gas chromatography

analysis

20 experiments + repetitions

Temperature: 600, 700, 750, 800 °C

Pressure: 1, 5, 10, 20, 30 bar

Gas atmosphere: Argon

Argon flow rate: 60 l/h (STP)

Process conditions

Feedstock: Brown coalfrom Central Germany

Particle size: 40…100 µm

Moisture content: predried at 105 °C

Feed rate: about 6.2 g/min

Feed parameter



Feedstock characterisation

Ash content determination at: * … 450 °C; ** … 815 °C

Brown coal from Central Germany

X‐ray fluorescence analysisProximate and ultimate analysis

Proximate analysis in wt.‐%

Moisture (r) 44.1

Ash (d) 22.2* 17.6**

Volatile Matter (d) 52.8

Fixed Carbon (d) 25.0 29.6Sum (d) 100.0 100.0Ultimate analysis in wt.‐% (daf)Carbon 76.3 72.0

Hydrogen 6.5 6.1

Nitrogen 0.6 0.6

Combustible Sulphur 2.9 2.7

Oxygen 13.8 18.6Sum 100.0 100.0Heating value in kJ/kg (d)HHV 24,913

LHV 23,817

Original Ashsample 450 °C 815 °C

Carbon (from carbonates) n.d. 0.95 b.d.l.Oxygen ‐ 49.01 47.76Sodium 0.01 b.d.l. b.d.l.Magnesium 0.17 1.33 1.42Aluminum 1.65 13.17 13.77Silicon 2.45 15.65 16.71Sulphur 3.42 7.46 6.85Chlorine 0.01 0.03 b.d.l.Pottassium 0.05 0.42 0.62Calcium 1.67 10.63 11.40Titanium 0.06 0.41 0.43Ferrum 0.07 0.59 0.65Barium 0.03 0.16 0.18Traces 0.02 0.19 0.21Sum 9.60 100.00 100.00


III. Results

Particle and gas residence time

Coal properties

• particle size range: 40…100 µm

• volume mean diameter: 60 µm

• sphericity (WADELL): 0,8

• apparent density: 950 kg/m3

Gas properties

• kinematic viscosity and densitycalculated with Aspen Properties

• real gas behaviour according toREDLICH‐KWONG‐SOAVE

Particle velocity (mean value of)

• STOKES (Rep ≤ 0,25 )

• BERANEK, MARTIN, KUNII (Rep = f(Ar))

• HAIDER‐LEVENSPIEL (cd = f(Rep, Ψ))

Particle residence time

+

0

5

10

15

20

25

600 650 700 750 800

Particlereside

ncetim

e in s

Temperature in °C

1 bar 5 bar 10 bar 20 bar 30 bar

pressure

Temperature Pressure1 bar 5 bar 10 bar 20 bar 30 bar

600 °C 3.2 12.4 25.3 51.9 77.2700 °C 2.2 8.9 19.6 36.2 52.8750 °C 3.3 6.3 15.9 31.3 43.2800 °C 2.0 7.5 12.9 26.7 37.2

Gas residence time

Particle residence time


III. Results

Pressure influence on product yields

0

10

20

30

40

50

60

70

80

0 5 10 15 20 25 30 35

Prod

uct y

ields in wt.%

(d)

Pressure in bar

0

10

20

30

40

50

60

70

80

0 5 10 15 20 25 30 35

Prod

uct y

ields in wt.%

(d)

Pressure in bar

Char Liquid product Gas

0

4

8

12

16

20

0 5 10 15 20 25 30 35

Prod

uct y

ields in wt.%

(d)

Pressure in bar

Liquid product Reaction water Tar/oil

0

4

8

12

16

20

0 5 10 15 20 25 30 35

Prod

uct y

ields in wt.%

(d)

Pressure in bar

600 °C

800 °C

Pressure↑• Main effect on product yields up to about 10 bar• Decrease of char and liquid product yield• Increase of pyrolysis gas yield• Tar yield shows minimum at 5 barTemperature↑• slightly decreasing char and liquid product yield• strong rise in gas yields


III. Results

Pressure influence on yields of main gas components

0

50

100

150

200

250

0 5 10 15 20 25 30 35

Yield in l (STP

)/kgCo

al (d

)

Pressure in bar

H2 CH4 CO CO2

0

50

100

150

200

250

0 5 10 15 20 25 30 35

Yield in (STP)l/kgCo

al (d

)

Pressure in bar

H2 CH4 CO CO2

600 °C 800 °C

Pressure↑

• Increase in CH4 production indicates favouring of secondary crackingreactions of volatiles (more distinctive at higher temperatures).

• Slight increase of CO, CO2 and H2 yields mainly up to 10 bar

Temperature↑

• Strong increase in H2, CH4 and CO production, while effect on CO2 is less


III. Results

Pressure influence on yields of gaseous hydrocarbons

0

5

10

15

20

25

30

35

40

0 5 10 15 20 25 30 35

Yield in l (STP

)/kgCo

al(d)

Pressure in bar

C2H6 C2H4 C3H8 C3H6 C4H10

0

5

10

15

20

25

30

35

40

0 5 10 15 20 25 30 35

Yield in l (STP

)/kgCo

al(d)

Pressure in bar

C2H6 C2H4 C3H8 C3H6 C4H10

600 °C 800 °C

Pressure↑

• Increase in C2H6 yield (≤ 700 °C), decrease at p ≥ 5 bzw. 10 bar (T≥700 °C)• Reduction of saturated hydrocarbons (C2H4, C3H6) due to secondary cracking stronger effect at higher temperatures

• Increase of C3H8 yield up to about 15 bar, then slight reduction (600 °C)

• C3H8 dissappears at T>600 °C


III. Results

Kinetic parameters for main gas components

Arrhenius plot fortotal gas formation

11

y = ‐4431.4x + 1.3242R² = 0.868

y = ‐5435.4x + 1.6335R² = 0.9913

y = ‐4810.8x + 0.4808R² = 0.9491

y = ‐4258.2x ‐ 0.4087R² = 0.999

y = ‐4563x ‐ 0.1754R² = 0.9998

‐5.5

‐5.0

‐4.5

‐4.0

‐3.5

‐3.0

‐2.59.0E‐04 1.0E‐03 1.1E‐03 1.2E‐03

ln k [k

mol

gas/(kmol

coal∙ s)] daf

1/T [1/K]

1 bar 5 bar 10 bar 20 bar 30 bar

Pressure 1 bar 5 bar 10 bar 20 bar 30 barGas total 37 45 40 35 38

H2 115 123 93 90 84

CH4 54 68 80 51 50

CO 44 52 34 49 62CO2 14 25 23 16 19

Pressure 1 bar 5 bar 10 bar 20 bar 30 barGas total 3.8 5.1 1.6 0.7 0.8

H2 5.1*103 8.7*103 143 72 33

CH4 5.8 17.8 60.4 1.6 1.2

CO 1.3 1.8 0.1 0.5 1.9CO2 0.05 0.1 0.05 0.01 0.02

Activation energy EA in kJ/mol Frequency factor k∞ in s‐1

∙ ∙

∙

Arrhenius equation

• For calculation of kineticparameters for total gas andgas components formation

DecreasingE A


IV. Future Prospects

New drop tube reactor – PYMEQ

Feeds

Coal, max. 500 g,

up to 10 g/min

40…1,000 µm

Moisture: < 10 wt.%

Equipment

Heated lenght: 2,500 mm

Reactor ID: 18 mm

2‐stage condensing system

(‐20 °C)

Online MS for gas analysis

2 sampling points (volatiles)

1 optical port

Process conditions

T ≤ 800 °C, p ≤ 100 bar (g)

Argon, H2, steam, CO2,

CH4 and mixtures

(rate: ≤ 400 l/h STP)

PYMEQ – PYrolysis MeasurementEQuipment

• Reasearch task 1: Structuredetermination of energy sources

• Pyrolysis as important process

• New reactor for investigationof pyrolysis behaviour of coals

• Parameter studies, determination of reactionmechanisms and kinetics

• Cooperation with chemists fordetailled tar and feed analytik

German Center for Energy Resources Freiberg – DER

• Better understanding aboutoccuring reactions and influencingparameters

• Correlation between feedproperties and conversion behaviour

Results


IEC – TU Bergakademie Freiberg

Contact:Denise Reichelphone + 49 (0)3731 / 39 4450mail [email protected]‐freiberg.de

Acknowledgement

Thanks to:

German Federal Ministry of Education and Research

RWE AG, Vattenfall Europe AG, MIBRAGmbH and Romonta

Thank you for your attention – Questions?

Stephan Sieglphone + 49 (0)3731 / 39 4815mail [email protected]‐freiberg.de


III. Results

Pressure influence on product yields

0

10

20

30

40

50

60

70

80

0 5 10 15 20 25 30 35

Prod

uct y

ields in wt.%

(d)

Pressure in bar

0

10

20

30

40

50

60

70

80

0 5 10 15 20 25 30 35

Prod

uct y

ields in wt.%

(d)

Pressure in bar

Char Liquid product Gas

0

4

8

12

16

20

0 5 10 15 20 25 30 35

Prod

uct y

ields in wt.%

(d)

Pressure in bar

Liquid product Reaction water Tar/oil

0

4

8

12

16

20

0 5 10 15 20 25 30 35

Prod

uct y

ields in wt.%

(d)

Pressure in bar

600 °C

800 °C

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