INTRODUCTION Biogas contains trace level concentrations of volatile - - PowerPoint PPT Presentation

▶
introduction
SMART_READER_LITE
LIVE PREVIEW

INTRODUCTION Biogas contains trace level concentrations of volatile - - PowerPoint PPT Presentation

Apr 04, 2024 161 likes •291 views

C. Pascual 1,2 , E. Arnaiz 1,2 , R. Muoz 1,2 , R. Lebrero 1,2 1 Department of Chemical Engineering and Environmental Technology, School of Industrial Engineering, Valladolid University, Dr. Mergelina, s/n, Valladolid, Spain. 2 Institute of

slide-1
SLIDE 1
  • C. Pascual1,2, E. Arnaiz1,2, R. Muñoz1,2, R. Lebrero1,2

1 Department of Chemical Engineering and Environmental Technology, School of Industrial

Engineering, Valladolid University, Dr. Mergelina, s/n, Valladolid, Spain.

2 Institute of Sustainable Processes, University of Valladolid, 47011, Valladolid, Spain.

1

slide-2
SLIDE 2

INTRODUCTION

➢ Biogas contains trace level concentrations of volatile methyl siloxanes (VMS)

SiO2 crystalline deposit

  • Decreased efficiency of the equipment

▪ Corrosion ▪ Erosion ▪ Clogging of pipes

  • Increased maintenance costs

➢ Removal of VMS from biogas prior energy valorization is mandatory

Siloxanes concentration in biogas = 20-400 mg m-3 Maximum concentration for biomethane injection in natural gas grid 10 mg m-3

2

slide-3
SLIDE 3

INTRODUCTION

➢ Conventional physical-chemical processes for siloxanes removal:

  • High operating and investment cost

➢Biological processes:

  • Low-cost
  • Environmentally friendly

Physical-chemical processes RE (%) Disadvantages Adsorption 90-99 Regeneration/replacement of the adsorbent Absorption > 90 Cooling to avoid organic solvent emissions Corrosive nature of acid solutions Alkaline deposits (alkaline absorbent solutions) Cryogenic condensation > 90 Extreme operating temperatures (-25, -70 ºC) Membrane separation > 80 Compressors or vacuum pumps energy consumption

3

slide-4
SLIDE 4

Mineral medium Air + VMS Air Liquid recycling Mineral medium + Non-aqueous phase Air + VMS Air Liquid recycling

Aqueous phase Gas phase Gas phase

Non-aqueous phase: Silicone oil

Aqueous phase

Biotrickling Filters (BTFs)

One-phase biotrickling filter (1P-BTF) Two-phase partitioning biotrickling filter (TP-BTF)

4

slide-5
SLIDE 5

BTFs: Experimental setup

1- BTF 2- Nutrient reservoir 3- Syringe pump 4- Rotameter 5- Mixing chamber 6- Peristaltic pump 7- Gas sampling port 3 2 1 4 5 6 7

  • Gas flow: 33 mL min-1
  • V = 2 L
  • EBRT = 1 h
  • [VMS] ~ 650 mg m-3

Air Mixing chamber Flowmeter Gas outlet

GS

Syringe pump (siloxanes) Nutrients reservoir Liquid recycling

GS

L2, L3, D4 and D5 Compound Abbreviation Formulation Hexamethyldisiloxane L2 C6H18OSi2 Octamethyltrisiloxane L3 C8H24O2Si3 Octamethylcyclotetrasiloxane D4 C8H24O4Si4 Decamethylcyclopentasiloxane D5 C10H30O5Si5

5

slide-6
SLIDE 6

BTFs: Abiotic test

Inlet concentration (●) Outlet concentration (●) PVC column (I) Packing material (II) Mineral medium (III) Mineral medium + silicone oil (IV)

6

slide-7
SLIDE 7

BTFs: Experimental conditions

1P-BTF Feed Stream Time curse (Days) VMS Concentration (mg m-3) S1 VMS loaded air stream 0 - 46 514.7 ± 125.6 S2 Clean air stream 47 - 76

  • S3

VMS loaded air stream 77 - 124 719.3 ± 203.4 S4 VMS loaded air stream 125 -137 1287.9 ± 216.8 S5 VMS loaded air stream 138 - 160 650.9 ± 126.9 TP-BTF Feed Stream Time curse (Days) VMS Concentration (mg m-3) S1 VMS loaded air stream 0 - 21 624.0 ± 172.4 S2 Clean air stream 22 - 70

  • S3

VMS loaded air stream 70 - 113 640.0 ± 198.0

7

slide-8
SLIDE 8

1P-BTF: VMS concentration and RE

Inlet concentration (●) Outlet concentration (●) Day 81: System reinoculation ( )

S1 (1P-BTF) S3: (1P-BTF) S4 (1P-BTF) S5: (1P-BTF)

VMS Concentration (mg m-3) S1 514.7 S2

  • S3

719.3 S4 1287.9 S5 650.9 8

slide-9
SLIDE 9

TP-BTF: VMS concentration and RE

Inlet concentration (●) Outlet concentration (●) S1 (TP-BTF) S3: (TP-BTF)

VMS Concentration (mg m-3) S1 624.0 S2

  • S3

640.0 9

slide-10
SLIDE 10

Total VMS removal - Comparative results

200 400 600 800 1000 1200 1400 20 40 60 80 100 120 Concentration (mg m-3) Time (d)

TP-BTF

S1 S2 S3 500 1000 1500 2000 50 100 150 Concentración (mg m-3) Time (d)

1P-BTF

S1 S2 S3 S4 S5

Inlet total VMS concentration (●) Outlet total VMS concentration (●) Day 81: System reinoculation ( )

10 20 30 40 50 60 70 80 90 100

L2 L3 D4 D5 Total VMS

RE (%) 0.00 0.10 0.20 0.30 0.40 0.50 0.60 0.70

L2 L3 D4 D5 Total VMS

EC (g m-3 h-1)

TP-BTF (S1) 1P-BTF (S1)

10

slide-11
SLIDE 11

Conclusions

➢ REs and ECs significantly higher in TP-BTF compared to 1P-BTF (~ 80 % higher)

  • VMS low solubility in aqueous phase
  • Reduced mass transfer

➢ The presence of an organic phase (silicon oil) is of key importance in VMS removal ➢ The highest REs were obtained for D4 and D5 (the compounds with highest molecular weight

and lowest volatility)

➢Future work:

  • Study of the microbial communities in siloxane removal TP-BTF
  • Metabolites analysis
  • Optimization of lab-scale BTF for siloxanes removal

▪ Lower EBRT ▪ VMS removal under anoxic conditions

11

slide-12
SLIDE 12

Contacto: Celia Pascual (celia.pascual@iq.uva.es)

www.ips.uva.es http://gastreatment-microalgaeresearchgroup.blogspot.com/

Follow us in Twitter: @VOC_Odours Visit us in: Facebook: facebook.com/VocOdoursGroup

12