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
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