GASIFICATION OF WASTE TIRE: SYSTEMATIC ANALYSIS

AND NUMERICAL SIMULATION

Prof. Isam Janajreh and Syed Shabbar (Ph.D.)

Mechanical and Materials Engineering Department, Masdar Institute, Abu Dhabi, UAE

ijanajreh@masdar.ac.ae

Masdar Institute Waste to Energy Lab

ATHENS 2014 International Conference on Sustainable Solid Waste Management,

12-14 June 2014, Royal Olympic Athens Hotel, Athens, Greece

Contents2

Introduction

Problem definition

Motivation

Objective

Gasification

Material characterization

Proximate analysis

Ultimate analysis

Calorific value analysis

Low fidelity simulation

Thermodynamic modeling of gasification using,

Gibbs energy minimization method

High fidelity simulation

CFD simulation with coupled radiation and reaction kinetics

Conclusion

Problem definition3

Introduction

Material

Characterization

Low Fidelity

Simulation

High Fidelity

Simulation

Conclusion

}

• Of the 1.2 billion generated tires only 50% of waste tire are being recycled worldwide [Rubber Div., 2008]

• None bio-degradable and can last 100 years or more if no proper handling is carried out

• Illegal dumping/burning can be seen everywhere and incorrect disposal is environmentally hazardous

• Wasted resources/business opportunities: • Rereading and granulation• Energy & chemicals• Carbon black• Metal• Liquid and gas fuel etc.!

Melbourne Australia 2006, tire pile fires lasted over a month sending up an acid black plume that seen miles away contains toxic chemicals and air pollutants just as toxic chemicals are released into surrounding water supplies by oily runoff from tyre fires

Stock availability and potential4

• Worldwide, an estimated 1.2 billion waste tiers are generated every year. Only a fraction of these tyres are currently recycled with the majority being incinerated, dumped or stockpiled.

• UAE: 2,500 tiers is collected in Sharjah per day or 63 tons/daily, [Sharjah Municipality, 2012]

• Abu Dhabi available stock over 5,000,000 tiers or 126,000 tons [CWM, 2012]

• 120 tons daily gasifier ensure stocks for 3 years, but within these three years another 69,000 is collected,

• This quantity will last for 19 months, by the end of this 19 months another 35,910 tons is collected

• This will last for approxmately10 months…and so on.

• Other 4 Emirates: Ajman, Umm Alqaiwain, Ras AL Khaima and Al Fujaira together produce and have in stock twice as much as the Emirate of Abu Dhabi at this moment [Beah, 2012].

• Sharjah Emirate has at this moment over 5,000,000 tires in stock [Beah, 2013]

• Dubai Emirate has over 5,000,000 ties in stock [Duabi Municipality, 2011]

• Emirates have got all the potential to have their own plants as Abu Dhabi.

4

Introduction

Material

Characterization

Low Fidelity

Simulation

High Fidelity

Simulation

Conclusion

Location Generation (million) Stockpile (million)

USA 240 500 to 3,000

Australia 8 20

Japan 100 100

Europe 250 3,000

* Small tire weight/availbility 12kg/60%, large 45kg/60% production is based on 345 days per year).

Motivation and Objective5

Motivation

Gasification:

Efficient way to convert solid feedstock to fuel

(syngas & chemicals)

Feedstock /product flexibility

Syngas is used in IGCC as fuel

Objective

Material characterization

Proximate, ultimate and calorific value analysis

Low fidelity simulation

Thermodynamic analysis of gasification

High fidelity simulation

Coupled CFD analysis with radiation and reaction kinetics

Introduction

Material

Characterization

Low Fidelity

Simulation

High Fidelity

Simulation

Conclusion

Gasifier

T=1,000-1,500 C

P=20-40bar

Air Separation

UnitO2

Steam

Air

Gas cleaningCO shift and

CO2 removal CO2 for

storage

Sulfur H2

Combustor

Heat recovery steam

generator

Flue gas

GeneratorSyngas Gas turbine

Steam

turbine Generator

Electric

Power

Electric

Power

CondenserPump

N2

Ash

Gas cooler

Coal

Tire

shreds

Feedstock

Gasification6

Gasification is a thermo-chemical pathway to convert any carbonaceous

feedstock into syngas.

22524432212222 76.3/)76.3( NmOHxCOxCHxHxCOxCOOHnNOmNOCH zyx

Global Gasification Reaction

Oxidizer Moderator Syngas Combustion products

Intermediate Gasification Reactions [Higman et. al.]

kmolMJOHOH

kmolMJCOOCO

kmolMJCOOC

/2422

1

/2832

1

/1112

1

222

22

2

1) Combustion reactions

2) Boudouard reaction

kmolMJCOCOC /17222

3) Water gas reactionkmolMJHCOOHC /13122

4) Methanation reaction

kmolMJCHHC /752 42

5) CO shift reaction

kmolMJHCOOHCO /41222

6) Steam methane reforming reactionkmolMJHCOOHCH /2063 224

O2

CnHmOx

Slag

CO2

H2

CO

Stage 2:

2 -4 burners

1200 1600

Syngas

AshStage 1:

2 -4 burners

CO2,H2O

Temperature, oC

Lower: Stoichiometric O2

upper: Lean O2

Introduction

Material

Characterization

Low Fidelity

Simulation

High Fidelity

Simulation

Conclusion

Material Characterization7

Proximate analysis

Ultimate analysis

Calorific value analysis

Introduction

Material

Characterization

Low Fidelity

Simulation

High Fidelity

Simulation

Conclusion

Composition Tire

Proximate (Wt.%)

Moisture 1.0

Volatile Matter 68.0

Fixed Carbon 23.2

Ash (dry) 8.8

Ultimate (Wt.%) (dry)

C 73.8

H 6.8

N 0.3

S 1.3

O 9.0

Ash 8.8

HHV (MJ/kg) 36.0

MW (kg/kmole) 14.83

CH1.1057O0.0915N0.0035S0.0066

60

65

70

75

80

85

90

95

100

20 120 220 320 420 520 620 720 820

Weig

ht (

%)

Temperature (C)

5 C/min

10 C/min

15 C/min

20 C/min

Thermodynamic model of gasification through

Gibbs Energy Minimization Lagrange multiplier method

8

A relatively easy method to formulate a large number of product species

as compared to Equilibrium constant method.

Function: ),,,,,...,2,1(0)ln(, SNOHCkspeciesofnumberiax

xRTG

k

ikk

total

io

if

Reactants QOHnNOmSNOCH wzyx 222 )76.3(

Products

Feedstock Oxidizer Moderator Heat Input

44 species: Product of gasification

C(g) CH CH2 CH3 CH4 C2H2 C2H4 C2H6 C3H8 H H2

O O2 CO CO2 OH H2O H2O2 HCO HO2 N N2

NCO NH NH2 NH3 N2O NO NO2 CN HCN HCNO S(g)

S2(g) SO SO2 SO3 COS CS CS2 HS H2S C(s) S(s)

Introduction

Material

Characterization

Low Fidelity

Simulation

High Fidelity

Simulation

Conclusion

Thermodynamic model of gasification through

Gibbs Energy Minimization Lagrange multiplier method

9

Model formulation:

• Elemental balance

• Carbon balance

• Hydrogen balance

• Oxygen balance

• Nitrogen balance

• Sulfur balance

• Gibbs Energy functions

• Energy balance

• Total 50 Equations

5 Equations

44 Equations

1 Equation

0)ln(, k

ikk

total

io

if ax

xRTG

0)()ln(

,

02)ln(

,

0)4()ln(

,

:

31,

22

2,

21

4

4,

total

COo

COf

total

Ho

Hf

total

CHo

CHf

x

xRTG

monoxidecarbonfor

x

xRTG

hydrogenfor

x

xRTG

Methanefor

FunctionEnergyGibbsofExamples

Introduction

Material

Characterization

Low Fidelity

Simulation

High Fidelity

Simulation

Conclusion

Thermodynamic model of gasification through

Gibbs Energy Minimization Lagrange multiplier method

10 Model validation (air ratio (a)=0.3 kmole)

Feedstock: high vale coal [5]

Empirical formula: CH0.6923O0.2124N0.0105S0.0013

Higher heating value: 21.1 MJ/kg

Model

a=0.3

[5] Li, X., et al., Equilibrium modeling of gasification: a free energy minimization approach and its application to a circulating fluidized bed coal gasifier. Fuel, 2001. 80(2): p. 195-207.

Introduction

Material

Characterization

Low Fidelity

Simulation

High Fidelity

Simulation

Conclusion0.0001

0.001

0.01

0.1

1

10

100

600 800 1000 1200 1400 1600

Eq

ulibri

um

mola

r co

nte

nt

(%)

Temperature (K)

N2

H2

CO

CO2H2O

CH4

Li et al.[5]

Thermodynamic model of gasification through

Gibbs Energy Minimization Lagrange multiplier method

11

ResultsIntroduction

Material

Characterization

Low Fidelity

Simulation

High Fidelity

Simulation

Conclusion

𝑪𝑯𝟏.𝟏𝟎𝟓𝟕𝑶𝟎.𝟎𝟗𝟏𝟓 + 𝟎. 𝟗𝟎𝟖𝟓 𝑯𝟐𝑶+𝒎 𝑶𝟐 + 𝟑. 𝟕𝟔𝑵𝟐

H2O gasification

0

10

20

30

40

50

60

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

0.9 1 1.1 1.2 1.3 1.4 1.5 1.6 1.7 1.8 1.9 2

CG

E (

%)

Pro

duct

(m

ole

fra

ctio

n),

Tem

per

ature

(K

)/20

00

Equivalence ratio (Φ)

Maximum CGE (51%)@ 1050 K

Temperature (K)/2000

CGE

N2

COH2

CO2

H2O

Cs

Species Syngas mole (%)

CO 7.2

CO2 12.2

H2 4.57

H2O 6.63

O2 0

N2 68.4

CH4 0

Temperature (K) 1051

Equivalence ratio (Φ) 1.37CGE 51%

Numerical approach

Coupled thermo-chemical simulation with CFD12

Gasifier geometry and boundary conditionsIntroduction

Material

Characterization

Low Fidelity

Simulation

High Fidelity

Simulation

Conclusion

Tire inlet condition

Inlet temperature (K) 300

Inlet velocity (m/s) 1.70E-04

Diameter (mm) 0.1

Air inlet condition

Inlet temperature (K) 300

Inlet velocity (m/s) 0.195

Gasifier Inlet Conditions

Numerical approach

Coupled thermo-chemical simulation with CFD13

Governing Equations:

Mass, momentum and energy

density, velocity, temperature

Reaction terms and kinetics

Introduction

Material

Characterization

Low Fidelity

Simulation

High Fidelity

Simulation

Conclusion

sourcediffusionadvectiverateTime

Sxx

uxt ii

i

i

ii

i

ittmi

i

ii

i

i SRx

mScD

xmu

xm

t

/,

)()( 44pRppfg

ppp

ppp TTAh

dt

dmTThA

dt

dTcm Reaction Kinetic Parameters Aj , Ej [kJ/mol]

R1 2 𝐶𝑂 + 𝑂2 → 2 𝐶𝑂2

𝐴 = 1017.6[(m3mol-1)-0.75s-1], 𝐸 = 166.28

R2 2 𝐻2 + 𝑂2 → 2 𝐻2𝑂 𝐴 = 1𝑒11 [m3mol-1s-1], 𝐸 = 42

R3 𝐶𝑂 + 𝐻2𝑂 ↔ 𝐶𝑂2 + 𝐻2 𝐴 = 0.0265, E= 65.8

R4 𝐶 𝑠 + 𝑂2 → 𝐶𝑂2 𝐴 = 5.67𝑒9 [s-1], 𝐸 = 160

R5 𝐶 𝑠 + 𝐶𝑂2 → 2 𝐶𝑂 𝐴 = 7.92𝑒4 [m3mol-1 s-1], 𝐸 = 218

R6 𝐶 𝑠 + 2 𝐻2 → 𝐶𝐻4 𝐴 = 79.2 [m3mol-1 s-1]𝐸 = 218

R7 𝐶 𝑆 + 𝐻2𝑂 → 𝐶𝑂 + 𝐻2 𝐴 = 7.92𝑒4 [m3mol-1 s-1], 𝐸 = 218

R8 𝑣𝑜𝑙 + 0.4 𝑂2 → 1.317 𝐶𝑂 + 2.09 𝐻2

+ 0.064 𝑁2 𝐴 = 1𝐸15 [m3mol-1 s-1], 𝐸 = 1𝐸8

Transport equation

Discrete particle interaction

n

r

riii

N

j

N

j

v

rjbrjfririri RMRandCkCkvvR rjrj

1

,

1 1

,,,,,ˆ)(ˆ

*,

*,

pP

PPPDP u

dt

xdguuF

dt

ud

;

Calculation procedure of feedstock conversion:(a) Solve the continuous phase

(b) Introduce and solve for the discrete phase

(c) Recalculate the continuous phase flow using the inter-

phase exchange of momentum, heat, and mass

(d) Recalculate the discrete phase trajectories

(e) Repeat c and d steps until a convergence is attained

])1([ 00)/(

pvp

RTEpmfmAe

dt

dm

i

N

i

ri

k

ki

N

i

ri SvSvrf

rb

1

,

1

,

,

,

Numerical approach

Coupled thermo-chemical simulation with CFD14

Introduction

Material

Characterization

Low Fidelity

Simulation

High Fidelity

Simulation

Conclusion

Figure: Temperature (K) distribution

inside gasifier

Figure: Velocity (m/s) distribution

inside gasifier

Numerical approach

Coupled thermo-chemical simulation with CFD15

Introduction

Material

Characterization

Low Fidelity

Simulation

High Fidelity

Simulation

Conclusion

0

0.02

0.04

0.06

0.08

0.1

0.12

0.14

0.16

0.18

0.9 1 1.1 1.2 1.3 1.4 1.5 1.6 1.7 1.8 1.9 2

Mo

le f

ract

ion

Equivalence ratio (Φ)

CO Equilibrium CO CFDH2 Equilibrium H2 CFDCH4 Equilibrium CH4 CFDCO2 Equilibrium CO2 CFDH2O Equilibrium H2O CFD

CO

H2

H2O

CO2

-10

0

10

20

30

40

50

60

500

700

900

1100

1300

1500

1700

0.9 1 1.1 1.2 1.3 1.4 1.5 1.6 1.7 1.8 1.9 2

CG

E

Tem

pe

ratu

re (

K)

Equivalence ratio (Φ)

Temperature Equilibrium

Temperature CFD

CGE Equilibrium

CGE CFD

CH4

CGE

Temp

Conclusions16

Material characterization is performed to measure the proximate and ultimate composition of tire along with its high heating value.

Simulation low vs high fidelity:

Low fidelity Gibbs minimization approach shows the maximum tire cold gasification efficiency is 51%.

High fidelity CFD simulation is favorably compared to the results of Gibbs energy minimization model

The Gibbs energy minimization model can be use initially to predict the quality of syngas without going for tedious CFD simulation or experimental approach.

What you need to know:

Thermochemical conversions is making a strong comeback as sustainable energy source and efficiency enhancement.

This technology can be deployed as renewable source for million of tons of waste streams disposed of at landfill and risking our ecological system.

Modeling ad simulations are needed at the conceptual level to increase the process efficiency and throughput.

Introduction

Material

Characterization

Low Fidelity

Simulation

High Fidelity

Simulation

Conclusion

Acknowledgement:

17

The financial sponsorship of Masdar institute is highly acknowledged. Thank you ….Questions ?

18

Equilibrium constant approach

Global Gasification reaction

•Elemental balance

•Carbon balance

•Hydrogen balance

•Oxygen balance

•Nitrogen balance

•Equilibrium constant equation

•For Bouduard reaction:

•For CO shift reaction:

•For Methanation reaction:

•Energy balance between reactant and product

•Conversion Metrics

𝐶𝐺𝐸 =𝑥1 283800 + x2 283237.12 + x5 889000

𝐻𝐻𝑉𝑓𝑒𝑒𝑑𝑠𝑡𝑜𝑐𝑘

)()(1_1_

so

N

reacti

iso

N

prodi

i hhnQhhn

𝐶𝐻𝑥𝑂𝑦𝑁𝑧 +𝑚 𝑂2 + 3.76𝑁2 + 𝑛𝐻2𝑂 + 𝑝𝐶𝑂2 → 𝑥1𝐻2 + 𝑥2𝐶𝑂 + 𝑥3𝐶𝑂2 + 𝑥4𝐻2𝑂 + 𝑥5𝐶 +𝑧

2+ 3.76𝑚 𝑁2

)76.32

(

).(

).(

).(

54321

2

1

5

3

42

312

3

2

21

mz

xxxxxx

reactionnMethanatioforconstmEquilibriux

xxK

reactionshiftCOforconstmEquilibriuxx

xxK

reactionBoudouardforconstmEquilibriuxx

xK

total

total

total

1) Combustion reactions

2) Reduction reactions

Backup slide: