Modelling of Gasification ofRefuse-derived fuel (RDF) basedon laboratory experiments

Juma HaydaryDepartment of Chemical and Biochemical EngineeringInstitute of Chemical and Environmental EngineeringFaculty of Chemical and Food Technology

Slovak University of Technology in Bratislava, Slovakia

Cyprus 2016

Slovak University of Technology in Bratislava Faculty of Chemical and

Food Technology

Cyprus 2016

Institute of Chemical and Environmental Engineering

Reactor EngineeringReaserch Group

• Experimental study and mathematical modeling of fuel thermal processes

• Pyrolysis, gasification and combustion of solid fuels

• Biomass, polymer waste, MSW, and coal thermaland catalytic processingfor production energy andmaterials

National center for research and application of renewable energy sources

Cyprus 2016

Refuse-Derived Fuel (RDF)

Cyprus 2016

Biodegradables Metals Inorganics Hazardous wastes

RDF composition

Component Material wi [kg/kg]

Paper White paper, recycled paper0,6317

Foil LDPE, HDPE0,1578

Plastics Rigid plastics, polystyrene, polyurethane 0,1910

Textile Polyamide, polyester, cotton , wool0,0194

Cyprus 2016

Proximate and Elemental Composition of RDF

Com. Mois. VM* FC* ASH* C H N S O**

Wt. % 10 75.5 8.9 15.6 51.7 5.9 0.9 0.4 25.5

*moisture free basis**calculated to 100%

Cyprus 2016

Behaviour of Thermal decomposition

Cyprus 2016

Behaviour of Thermal decomposition

Cyprus 2016

Heating value of RDF

Component Heating value [kJ/kg]

Paper 13410

Foil 43860

Plastics 33570

Textile 19770Mixed RDF 20810

Cyprus 2016

Tar content measurement

20

30

40

50

60

70

80

90

600 700 800 900 1000 1100 1200

Tar (

mg/

g R

DF)

Temperature (°C )

Gasification Model Assumptions: • Steady state flow is

considered inside the gasifier

• No temperature and concentration gradient exist inside the reactor

• The residence time is enough long to reach complete decomposition of RDF and unreacted part of RDF is only carbon.

• Only the major species are considered in the product gases, i.e CO, CO2, H2, CH4, H2O, NH3, H2S, N2 and Tar

5 71 2 2 2 3 4 2 2 6 4 2

8 3 9 2 10 1 11 1

c eb d

c eb d

CH O N S x O x H O x CO x CO x H x CH x H Ox NH x H S x CH O N S

Global material balance of RDF gasification

RDFTAR

20,5C O CO

2 20,5CO O CO

2 2 20,5H O H O

4 2 2 22 2CH O CO H O

2 2C H O H CO

2 2C CO CO

4 2 23CH H O H CO

2 42C H CH

2 2 2CO H O CO H

Reactions:

ii

i

iia xPPK

0

Equilibrium constant:

RTG

eK ra

298298

298298298 STHG rrr ,

298298ifir HH 298298

ifir SS

298 ( 298)r r i piH H c T 298 ln298r r i piTS S c

Enthalpy balance:

2( )RDF O air steam R gas ash C lossH H H Q H H H Q

RQ – heat of reaction [J],

RDFH – enthalpy of RDF feed [J],

2( )O airH – enthalpy of oxygen and air respectively [J],

steamH – enthalpy of water steam [J],

gasH – enthalpy of gas [J],

ashH – enthalpy of ash [J],

CH – enthalpy of unreacted carbon [J],

lossQ – heat losses from the reactor [J]

( )R RDF i i c i iQ m wQ H n IF, Tair =TRDF=Tref, then RDFH =0, 2( )O airH =0

( )RDF i i c i i lossref

i pi C pC ash pash steam steam

m wQ H n QT T

n c m c m c m c

mRDF – mass flow of RDF feed [kg]

ni – mole flow of component i in the products [kmol]

wi – maas fraction of component i in the feed (paper, foil, plastics, textil Qi – lower heating value of component i in the feed (paper, foil, plastics, textile) [Jkg-1],

icH - heat of combustion of component i in the products [Jkmol-1]

mash – mass flow of ash [kg]

mash – mass flow of remaining carbon [kg]

msteam – mass flow of steam [kg]

pa shc – specific heat capacity of ash [Jkg-1K-1]

pCc – specific heat capacity of remaining carbon [Jkg-1K-1]

psteamc – specific heat capacity of steam [Jkg-1K-1]

Results of modelling RDF gasification

Observed parameters:Conversion of RDFReactor TemperatureGas compositionContent of pollutants (NH3, H2S, TAR)

Variables: Oxygen (air) to RDF mass ratioSteam to RDF mass ratio

020406080100120

0

500

1000

1500

0 1 2 3 4

Con

vers

ion

(%)

Tem

pera

ture

(°C

)

m(air)/m(RDF)Temperature Conversion

00,10,20,30,40,50,60,7

0 1 2 3 4

Mol

e fr

actio

n

m(air)/m(RDF)

H2COCH4CO2N2

Air Gasification

0

0,0005

0,001

0,0015

0,002

0,0025

0,003

0,0035

0

0,01

0,02

0,03

0,04

0,05

0,06

0,07

0,08

0,09

0,1

0 1 2 3 4

H2S

and

NH

3 m

ole

frac

tion

Tarm

ass

frac

tion

m(air)/m(RDF)

Tar H2S NH3

0

50

100

150

0

1000

2000

3000

0 0,2 0,4 0,6 0,8 Con

vers

ion

(%)

Tem

pera

ture

(K)

m(O2)/m(RDF)

Temperature Conversion

Gasification of RDF Using O2

00,10,20,30,40,50,60,7

0 0,2 0,4 0,6 0,8

Mol

e fr

actio

n

m(O2)/m(RDF)

H2COCH4CO2N2

Effect of RDF compositionCom. Wt. %Mois 10VM 75.5FC 8.9ASH 15.6C 51.7H 5.9N 0.9S 0.4O 25.5

0

50

100

150

0

1000

2000

3000

0 0,2 0,4 0,6 0,8

Con

vers

ion

(%)

Tem

pera

ture

(K)

m(O2)/m(RDF)

Temperature Conversion

Com. Wt. %Mois 1.2VM 80.22FC 5.23ASH 13.34C 51.66H 8.82N 0.66S 0.08O 25.42

Sensitivity Results Curve

R

HC

CON

XCH

4

XCO

2

XCO

XH2

TR K

0,20 0,25 0,30 0,35 0,40 0,45 0,50 0,55 0,60 0,65 0,70 0,75 0,80 0,85 0,90 0,95 1,00 1,05 1,10 1,15 1,20 1,258,0

8,5

9,0

9,5

10,0

10,5

11,0

11,5

12,0

12,5

13,0

13,5

14,0

14,5

15,0

15,5

16,0

16,5

17,0

17,5

18,0

18,5

19,0

19,5

20,0

35

40

45

50

55

60

65

70

75

80

85

90

95

100

0,00

0,05

0,10

0,15

0,20

0,25

0,30

0,35

0,40

0,45

0,50

0,10

0,11

0,12

0,13

0,14

0,15

0,16

0,17

0,18

0,19

0,20

0,21

0,22

0,23

0,24

0,25

0,26

0,27

0,00

0,05

0,10

0,15

0,20

0,25

0,30

0,35

0,40

0,45

0,50

0,55

0,175

0,200

0,225

0,250

0,275

0,300

0,325

0,350

0,375

0,400

0,425

0,450

0,475

0,500

600

800

1000

1200

1400

1600

1800

2000

2200

2400

2600

2800

3000

TR K XH2 XCO XCO2 XCH4 CO N HC

Effect of Steam in RDF Gasification

0

0,1

0,2

0,3

0,4

0,5

0 0,1 0,2 0,3 0,4 0,5

Mol

e fr

actio

n

m(Steam)/m(RDF)

H2COCO2

88,599,510

10001050110011501200

0 0,1 0,2 0,3 0,4 0,5

Hea

ting

Valu

e (M

J/kg

)

Tem

pera

ture

(K)

m(Steam)/m(RDF)

Temperature Heating value

Conclusion

October 2015

• For RDF studied in this work,100% of RDF conversion in gasification by air was reached at mair/mRDF=2,2. However, the gas heating value was 4,4 MJ/Nm3

• Gasification of RDF using Oxygen enables production of a gas with heating value around 10 MJ/Nm3 at mO2/mRDF=0,45

• Elemental Composition of RDF has a crutial effect on riquiredmair/mRDF

• Raw untreated gas tar content was 3.3 mass %; tar fraction content a solid phase insoluble in isopropanol

• By increasing the msteam/mRDF the content of H2 and CO2increased, However, the content of CO, reactor temperature and gas heating vale decreased

Thank you for attention