Microwave Pyrolysis of Plastic Waste by E Khaghani U of Aukland

MICROWAVE PYROLYSIS OF PLASTIC WASTES FOR PRODUCTION OF FUEL AND OTHER CHEMICALS

Department of Chemical and Materials Engineering 1

Elham Khaghani Professor M. M. Farid

Professor A. Williamson

Presentation outline 2

  Introduction  Research objectives  Pyrolysis background

 Thermal pyrolysis  Microwave pyrolysis

  Experimental thermal pyrolysis setup   Results and discussions   Proposed microwave induced pyrolysis setup   Conclusions   Future work

Research objectives Introduction 3

  Comprehensive literature review   Conducting thermal pyrolysis experiments   Developing the ASTMS method   Analysing the products using GC/FID   Designing the microwave heating system


  Introduction   Research objectives   Pyrolysis background

  Thermal pyrolysis   Microwave pyrolysis


Introduction 5

  Definition of pyrolysis: Pyrolysis can be described as the thermal decomposition of organic components in an oxygen-free atmosphere to yield char, oil and gas

  Key parameters in pyrolysis reaction reactor type pyrolysis temperature heating rate pyrolysis time operating pressure chemical composition of resins

Introduction 6

  Types of pyrolysis Pyrolysis Hea,ng rate Residence

,me Temperature (°C)

Reac,on environment

Pressure (bar)

Major product

Carboniza,on Very slow Hrs‐days 400 Combus4on 1 Charcoal

Conven,onal 10‐100 °C/min

10s‐10min <600 Primary /Secondary

1 Gas, Liquid, Char

Fast/Flash Up to 1000°C/s

<1s <600 Primary /Secondary

1 Liquid

>700 Primary 1 Gas Ultra Very high <0.5s 1000 Primary 1 Gas Vacuum Medium 2‐30s 400 Primary <0.1 Liquid

Introduction 7

• Candidates for pyrolysis

55%

15%

11%

9%

3% 7%

Fraction %

PE PP PVC PS Expanded PS ( fast food packagin) Others

Industrial process for pyrolysis Introduction 8

  Fuji fixed-bed pyrolysis process   Hamburg university process   VEBA pyrolysis process   BASF process   BP recycling plant

Fuji fixed-bed pyrolysis process Introduction 9

  Zeolite – based ZSM-5 catalysts

Maximum capacity 5000

tonne/year plastic wastes

80% oil

60% gasoline

20%

kerosene

20% diesel 15% gas

Hamburg university process Introduction 10

Maximum capacity 50 kg/h

25-45% gas 30-50% liquid

VEBA pyrolysis process

11

Synthetic oil produced by rotary kiln reactor at 650°C

VCC Veba Combi Cracking LPH Liquid Phase hydrogenation GPH gas Phase hydrogenation

Maximum capacity 40000 tonne/year

80% high quality liquid products

10%methane-butane gas and further

10%hydrogenation residues

BASF process Introduction 12

Maximum capacity 150000 tonne/year

20-30% gas 60-70% liquid

BP recycling plant Introduction 13

•  Nominal capacity 50 kg/h •  80%efficiency in converting plastic wastes into petrochemical •  The gas contains high content of ethylene and propylene

Why thermal pyrolysis? Introduction 14

  Limited supply of natural resources (crude oil and gas)   Fluctuation of high price and availability of crude   Decreasing toxic air emissions and reducing greenhouse gases   Recycle some of the stored energy within the waste plastics   Diminishing imports of crude oil

Sample Calorific value (MJ kg-1)

Polyethylene 46.50

Polypropylene 46.50

Polystyrene 41.90

Kerosene 46.50

Gas Oil 45.20

Heavy Oil 42.50

Pyrolysis products Introduction 15

Hydrogen Methane Ethane Ethene Propane Propene Butane Butene CO CO2 HCL HDPE 0.12 1.9 2.21 6.08 1.31 4.56 0.22 0.36 0 0 0.00 LDPE 0.05 1.14 1.67 4.00 1.33 4.00 0.32 2.00 0 0 0.00 PS 0.04 0.53 0.08 0.26 0.02 0.05 0.00 0.06 0 0 0.00 PP 0.05 0.93 1.45 3.52 1.00 3.53 0.23 1.29 0 0 0.00 PET 0.31 0.71 0.03 1.41 0.13 0.09 0.00 0.00 13.29 22.71 0.00 PVC 0.12 0.77 0.47 0.15 0.24 0.19 0.11 0.15 0 0 52.93

• Gas products

• Oil/wax products (C6-C60)

• Solid products: the major element is carbon

HDPE, LDPE and PP : mainly saturated alkane and alkene group liquids PVC :combination of alkane, alkene and aromatic compounds PS : aromatic compound generated from benzene ring PET : aldehydes, ketones, carboxylic acids, alcohols and aromatic compounds

PE PP PS PVC PET

Why microwave pyrolysis ? Introduction 16

  MW technology is environmentally friendly (is produced from electricity)   Volumetric heating leads to produce uniform

microstructure materials   The high heating rate   Quick respond to changes in process parameters   The nature of microwave heating is also much more

efficient compared to resistance heating

Microwave pyrolysis Introduction 17

Interaction of electromagnetic radiation with

materials

Reflection Conductor

Transmission Insulation

Absorption Dielectrics

18

Types of cavities

Single mode Multimode

Microwave pyrolysis Introduction

Dielectric theory

19

D=f (Temperature, ion concentration, ion size, dielectric constant, microwave frequency, viscosity of reacting medium)



Dielectric mechanisms


Electromagnetic wave propagation (Reflected and transmitted signals)


22

Available technologies  Semi batch reactor Ludlow Palafox et al. (2001)

 Continues conveyor belt type reactor Charles L.Emery (1993)

 Continues screw type reactor (under design) Petter Heyerdahl and Geoffrey Gilpin

 Continues type reactor James S. Klepfer (1999)

Schematic drawing of the microwave-induced pyrolysis of HDPE

Ludlow Palafox et al. (2001) 23

Schematic drawing of the microwave-induced pyrolysis

Charles L.Emery (1993) 24

Schematic diagram of the microwave-assisted pyrolysis system under design P. Heyerdahl and G. Gilpin (Norwegian Uni.)

25

Schematic diagram of the microwave pyrolysis of organic waste materials James S. Klepfer (1999)

26

Thermal pyrolysis setup 28

Results of thermal pyrolysis 30

  Effect of temperature 500°C 525°C 575°C

PLASTIC Oil/wax Gas Residue Oil/wax Gas Residue Oil/wax Gas Residue HDPE 74.04 25.96 0 73.30 26.7 0 73.20 26.8 0 LDPE 73.92 26.08 0 72.74 27.26 0 69.62 30.38 0 PP 77.30 22.70 0 77.20 22.80 0 75.76 24.24 0

Product analysis

  Shimadzu GC 2010 with FID   FORTEHT-5 column

  (25 m×0.22mm×0.10um)   0.1gr sample dissolved in 5 ml

carbon disulfide   Internal standard: C15 and C23   Standard mixture: D2887 (C6-

C44)   1 µl injected into column   Oven temperature:

start: 80°C followed by ramp 15°C/min to 160°C ,then ramp 30°C/min to 380°C (15 min)

  FID temperature: 400°C   Helium used as carrier gas

31

Gas Chromatograph –Flame Ionisation Detector (GC/FID)

Pyrolytic oil/wax composition of HDPE at 500°C

32

  GC/FID chromatogram

Diene

Alkene

Alkane

Carbon number distribution for the pyrolysis of HDPE 33

0

0.02

0.04

0.06

0.08

0.1

8 13 18 23 28 33 38 43

TIC

%

0

0.02

0.04

0.06

0.08

0.1

8 13 18 23 28 33 38 43 TI

C%

0

0.02

0.04

0.06

0.08

0.1

8 13 18 23 28 33 38 43

TIC

%

(a) 500 °C (b) 525 °C (c) 575 °C

*(c) 500 °C *(d) 600 °C *(e) 700 °C

*Obtained by Carlos Ludlow-Palafox and Howard A. Chase (2001)

0

0.02

0.04

0.06

0.08

0.1

8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40 42 44

TIC

%

Carbon Number

HDPE-500

HDPE-525

HDPE-575

Comparison of HDPE at 500°C, 525°C & 575°C 34

Comparison of LDPE at 500°C, 525°C, 575°C 35

0

0.02

0.04

0.06

0.08

0.1

0.12

8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40 42 44

TIC

%

Carbon Number

LDPE-500

LDPE-525

LDPE-575

Comparison of PP at 500°C, 525°C, 575°C 36

0

0.02

0.04

0.06

0.08

0.1

0.12

0.14

0.16

8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40 42 44

TIC

%

Carbon Number

PP-500

PP-525

PP-575

Comparison of HDPE-LDPE-PP at 575 °C 37

0

0.02

0.04

0.06

0.08

0.1

0.12

0.14

8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40 42 44

TIC

%

Carbon Number

HDPE-575

LDPE-575

PP-575

Evolution of diene compounds (C10-C22) 38

0

0.01

0.02

0.03

0.04

0.05

0.06

10 11 13 15 17 20 22

Alk

adie

ne T

IC%

Carbon number

HDPE500

HDPE525

HDPE575

Evolution of alkene and alkane compounds 39

0

0.01

0.02

0.03

0.04

0.05

0.06

8 15 26 31 36 39 44

Alk

ene

TIC

%

Carbon number

HDPE500

HDPE525

HDPE575

0

0.01

0.02

0.03

0.04

0.05

10 20 29 36 41 A

lkan

e TI

C%

Carbon number

HDPE500

HDPE525

HDPE 575

Proposed microwave induced pyrolysis setup 41

Schematic of the microwave pyrolysis of plastic apparatus: 1) Generator, 2) Isolator (Circulator + Dummy load), 3) Directional coupler, 4) 3-stub tuner, 5) Quartz reactor, 6) Nitrogen inlet, 7) Seal, 8) Bearing, 9) Gear transition, 10) Adjustable speed electrical machinery,11) Applicator (rotary kiln reactor), 12) Optical pyrometer, 13) Feed inlet, 14) Condenser, and 15) Product container.

Conclusions 43

  Thermal pyrolysis of polyolefines yielded mainly oil/wax   The maximum yield of oil/waxes (500°C to 575°C)

77.3% for PP>74.04% for HDPE> 73.92% for LDPE   The yield of oil/waxes decreased with the increase in temperature   GC chromatogram shows a homologous series of triplets (diene,

alkene, alkane)   The main chemical components of the oil/wax :

alkenes > alkanes > diene   The maximum yields of diene were observed at 525°C and for

alkenes and alkanes were recorded at 500 °C.

Conclusions 44

  The Maximum yields for carbon number distribution was   C10 to C15 for HDPE and LDPE   C8, C11, C15 and C16 for PP

  Concentration of aliphatic species above C32 were greatly reduced   The higher temperature favours of formation of higher yield of

heavier compounds between 500°C and 575°C   The average quantitative ratio of

alkane: alkene: diene at 500°C 1:1.61: 0.36 for HDPE 1:1.54: 0.29 for LDPE

Future Work 45

  Conduct microwave pyrolysis experiment using rotary kiln reactor   Simulate the electromagnetic field distribution   Mathematical modelling   Examine the effect of processing parameters   Characterise the oil/wax fraction using GC/FID   Kinetic study to investigate the effect of microwave on reaction rate   Convert batch process to continuous process   Construct the pilot scale reactor

46

Thank you

Questions?

Microwave Pyrolysis of Plastic Waste by E Khaghani U of Aukland

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