Air gasification of biomass and polyethylene using a staged gasifier - PowerPoint PPT Presentation

6th International Conference on Sustainable Solid Waste Management Air gasification of biomass and polyethylene using a staged gasifier in lab scale and pilot scale Speaker: Yong-Seong Jeong Univ. of Seoul

Contents 1. Introduction 2. Lab scale experiment 3.Pilot scale experiment 4. Summary

1. Introduction

Introduction: Gasification Source: Premium Engineering 2016 4

Introduction: Tar Tar is one of the main obstacles of gasification  Typical definition of tar All organic contaminants with a molecular weight larger than that of benzene  Tar problems Tar condenses during gasification at reduced temperatures, thus blocking and fouling process equipments such as engines and turbines  Tar tolerances for gas engine and turbines Application Allowable tar Conc. (mg/m 3 ) Reference Gas Engine 50 − 100 Milne & Evans (1998) Gas Turbine 5 Milne & Evans (1998) SOFC 1000 − 10000 Basu (2010) Methanol synthesis 0.1 Bui et al. (1994) via Fischer-Tropsch 5

Introduction: Tar removal methods-Primary method Primary method : Treatments inside the gasifier - Proper selection of the operating conditions (temperature, equivalence ratio, pressure) - Use of a proper bed additives or a catalyst (Ni-based catalyst) - Proper gasifier designs (fixed bed, fluidized bed) Gasifier Tar free gas Fuels Application Gas cleanup + Tar Removal Dust N, S, halogen Compounds Air/Steam/O 2 6

Introduction: Tar removal methods-Secondary method Secondary method: Gas cleaning after gasifier - Tar cracking either thermally or catalytically - Physical methods such as the use of a cyclone, a filter, a scrubber Tar Removal Tar free gas Fuels Application Gasifier Tar Gas cleanup Air/Steam/O 2 Downstream cleaning (Tar, dust, N, S, halogen Compounds) 7

Introduction: Typical tar removal equipment  OLGA tar removal system-ECN Tar removal apparatus Installation and operation cost is very high 8

Introduction: Two-stage UOS gasification process Hot filter Condensers Cyclone Tar cracking reactor Additives Electric furnace Thermocouples Chiller Distributor Silo (water) Thermocouples Screw feeder Distributor Water Gas Fluidized bed engine Pre-heater reactor Air, O 2 or Steam 9

Introduction: Aims Introduction: Aims  Aims of the research 1) Production a producer gas with low tar and high H 2 from the three-stage dried sewage sludge (DSS) and polyethylene (PE) gasification in lab-scale. 2) In-situ regeneration of activated carbon used as tar removal agent 3) Production a clean producer gas from wood pellet, DSS, and palm kernel shell (PKS) in a pilot-scale two-stage process . 10

2. Lab scale experiment

Experiment: Feed material  Characteristics of feed materials Proximate analysis (wt%) Ultimate analysis (wt%) 7.27 ± 0.01 29.88 ± 0.86 Moisture Carbon 50.30 ± 0.02 4.61 ± 0.08 Volatile matter Hydrogen 7.73 ± 0.35 4.34 ± 0.15 Fixed carbon Nitrogen 34.70 ± 0.32 25.41 ± 1.06 Ash Oxygen 1.06 ± 0.03 Sulfur DSS LHV (MJ/kg) 11.74 Proximate analysis (wt%) Ultimate analysis (wt%) 0.1 ± 0.01 85.2 ± 0.16 Moisture Carbon 99.9 ± 0.01 14.6 ± 0.07 Volatile matter Hydrogen 0.2 ± 0.01 Fixed carbon N.D. Oxygen Ash N.D. Sulfur N.D. LHV (MJ/kg) 40.3 LDPE 12

Experiment: Activated carbon  Characteristics of AC Proximate analysis Moisture Volatile matter Fixed carbon Ash (wt%) 0.9 ± 0.02 22.45 ± 0.60 64.95 ± 1.17 17.77 ± 0.73 Ultimate analysis Carbon Hydrogen Nitrogen Oxygen Sulfur (wt%) 78.51 ± 1.06 0.58 ± 0.01 0.43 ± 0.09 2.32 ± 0.02 0.39 ± 0.01 ICP analysis (ppm) Al Ca Fe Mg K 13173 13071 12977 3673 465 BET Micro pore volume Total pore volume Mean pore diameter Surface area (m 2 /g) analysis (cm 3 /g) (cm 3 /g) (nm) 1125.7 0.5380 0.6192 2.2004 13

Experiment: The three-stage gasifier Condensers Hot filter Cyclone Electric heater Tar cracking Thermocouples Additives reactor Chiller Distributor (water, 10 � ) Silo Vibrator Fluidized Raw gas sample gas sample gas sample bed Thermocouples reactor Thermocouples Screw feeders Sintered distributor Electrostatic precipitator Fluidized bed Water Auger reactor reactor Pre-heater Burner Clean gas sample : GC-TCD and FID Air 14

Experiment: The three-stage gasifier Tar cracking reactor Fluidized bed reactor Auger reactor 15

Experiment: Gasification conditions  Gasification conditions Run1 Run2 Run3 Run4 Run5 Feed material DSS DSS PE PE PE Auger reactor 645 659 503 495 502 temperature ( ° C) Fluidized bed reactor 807 811 828 823 820 temperature ( ° C) Tar-cracking reactor 814 820 811 820 820 temperature ( ° C) Equivalence ratio 0.35 0.34 0.30 0.30 0.32 Feed rate (g/min) 13.11 13.11 4.92 4.92 4.54 AC (g) 0 1600 0 1500 1500 Regeneration X X X X O • Gasification time: approximately 60 min • Amount of natural olivine used as the fluidizing bed material: 2200 g, 150 − 300 μ m • Flow rate of air: 15 NL/min 16

Results: Gasification results  Compositions of producer gas Composition (vol%) Run1 Run2 Run3 Run4 Run5 N 2 51.6 46.3 69.5 52.5 52.8 CO 2 14.5 9.1 11.1 5.0 4.7 H 2 14.1 28.5 6.9 26.72 26.8 CO 10.3 12.3 2.8 7.8 8.1 CH 4 6.4 3.8 8.7 7.9 7.7 C 2 H 2 0.15 0.005 N.D. N.D. N.D. C 2 H 4 2.13 0.023 5.9 0.002 0.001 C 2 H 6 0.18 N.D. 0.4 0.001 N.D. Benzene 0.39 0.014 1.1 0.002 0.002 >Benzene 0.069 0.004 0.1 N.D. N.D. LHV (MJ/Nm 3 ) 6.81 5.63 9.48 6.25 6.12 Impurities in producer gas Tar contents (mg/Nm 3 ) 2573 142 4528 N.D. 2 NH 3 in producer gas (ppmv) − 521 H 2 S in producer gas (ppmv) − 670 N.D.: not detected, − : beyond detection range (NH 3 : 3000, H 2 S: 2000 ppmv) 17

Results: Tar removal mechanism over activated carbon  Tar removal mechanism on AC 18

Results: Tar-free producer gas Tar cracking reactor Cracking & Reactions Adsorption Activated carbon Distributor Fluidized bed reactor Tar Tar Tar Feed material Tar Tar • Thermal or catalytic cracking reaction: pC n H x → qC m H y + rH 2 • Steam reforming reaction: C n H x + nH 2 O → (n+x/2)H 2 + nCO • Dry reforming reaction: C n H x + nCO 2 → (x/2)H 2 + 2nCO • Carbon formation reaction: C n H x → nC + (x/2)H 2 19

Experiment: In-situ regeneration  In-situ regeneration method Simply stopping feeding → oxidation of coke on activated carbon Gasifying agent (air) will react with tar & coke on AC Textural properties of activated carbon will be recovered 20

Results: Regeneration results  Textural properties of virgin and regenerated ACs Surface area Micropore volume Total pore volume Mean pore diameter (m 2 /g) (cm 3 /g) (cm 3 /g) (nm) Virgin 1125.7 0.5380 0.6192 2.2004 Run4 573.86 0.2597 0.2820 1.9505 Run5 938.75 0.4471 0.4792 1.9322  Pore size distributions of ACs micropores 3.0 • Large numbers of micro- and mesopores Virgin AC Regenerated AC (Run5) 2.5 Spent AC (Run4) disappeared after gasification dV p /dlog(d p ) (cm 3 /nm/mg) 2.0 • The AC after regeneration considerably recovered 1.5 textural properties 1.0 mesopores 0.5 0.0 1 10 100 21 Pore diameter (nm)

3. Pilot scale experiment

Experiment: Pilot scale equipment Tar cracking Flare stack Quenching reactor system Fluidized bed reactor 23

Experiment: Feed materials  Characteristics of feed materials Feed materials Wood pellet DSS PKS Proximate analysis (wt%) 8.34 ± 0.24 7.07 ± 0.31 1.1 ± 0.06 Moisture content 91.32 ± 0.28 51.53 ± 1.39 86.5 ± 0.23 Volatile matter 0.18 ± 0.10 3.99 ± 0.28 10.1 ± 0.07 Fixed carbon 0.16 ± 0.07 37.41 ± 1.02 2.4 ± 0.22 Ash Ultimate analysis (wt%) 55.26 ± 0.05 31.32 ± 0.11 49.7 ± 0.02 Carbon 7.28 ± 0.01 4.56 ± 0.08 5.9 ± 0.02 Hydrogen 0.32 ± 0.02 4.72 ± 0.02 0.7 ± 0.01 Nitrogen 36.96 ± 0.08 20.72 ± 0.31 36.5 ± 0.09 Oxygen 1.27 ± 0.01 Sulfur 0 0 LHV (MJ/kg) 18.5 13.2 20.5 24

Results: Composition of producer gas  Composition of producer gas Composition (vol%) Wood pellet DSS PKS N 2 42.2 43.2 43.4 CO 2 13.0 13.6 14.6 H 2 23.5 20.3 20.5 CO 15.9 17.0 18.0 CH 4 5.2 5.8 3.61 C 2 H 2 0.03 0.04 N.D. C 2 H 4 0.04 0.07 0.03 C 2 H 6 0.001 0.001 0.01 Benzene 0.05 0.05 0.06 >Benzene 0.001 0.01 0.001 LHV (MJ/Nm 3 ) 6.07 6.09 5.71 Tar contents (mg/Nm 3 ) 42 37 34 N.D.: not detected 25

Results: Auto-thermal operation  Auto-thermal operation 1200 Fluidized bed reactor Maintain ~800 ° C Tar cracking reactor 1000 Turn off preheater Temperature ( o C) 800 600 Start feeding 400 200 0 0 100 200 300 400 500 600 700 Time (min) 26

4. Summary

Summary  Effect of AC on tar removal and the hydrogen production Tar content in producer gas: 2573 → 142 mg/Nm 3 (DSS) • 4528 → 0 mg/Nm 3 (PE) • Hydrogen content: 14.1 → 28.5 vol%(DSS) 6.6 → 26.7 vol% (PE)  In-situ regeneration method recovered textural properties of AC • Surface area: 1125.7 (virgin) → 938.75 m 2 /g • Micropore volume: 0.5380 (virgin) → 0.4471 cm 3 /g  Pilot scale • Production of a producer gas with low tar and high H 2 without scrubber & EP • Auto-thermal operation during test 28

6th International Conference on Sustainable Solid Waste Management Thank you for your attention