Removal of VOCs from Air Streams using Membrane Technology

Transcription

1

2 Removal of VOCs from Air Streams using Membrane Technology Thomas McEvoy, Ashok Sharma, Stephen Conover Applied Membrane Technology Inc. Kamalesh K. Sirkar *, Gordana Obuskovic, Otto H. York Department of Chemical Engineering New Jersey Institute of Technology Yingie Qin, Chembrane Inc. C3P & NASA TECHNICAL WORKSHOP November 7,8, & 9th, 2007 Peniche, Portugal

3 Acknowledgements NASA DoD SGM, ERRC (at NJIT) Novartis Pharmaceuticals Corporation, E. Hanover, NJ. SERDP Project EPA , EPA NHSRC Membrane Separations and Biotechnology Program at NJIT

4 Environmental Market: Air Treatment Hollow Fiber Membrane Module Systems 11/26/2007

5 Volatile Organic Compounds (VOCs) are released to atmosphere through various N 2 /air streams The emissions have to be controlled by law Recovery of such VOCs is often economically beneficial There are a variety of techniques: Absorption, Adsorption, Refrigeration, Membrane Processes and Destruction

6 Chiller Membrane modules Feed stream VOC-depleted gas stream Compressor Liquid VOC VOC-enriched permeate stream Flow diagram showing the application of a membrane vapor permeation system to effluent gas treatment and VOC recovery: condenser on the compressed feed gas side. (Adopted from Lokhandwala et al., 1999.)

7 Types of Membrane Modules for Vapor Permeation Plate-and-frame module - contains a stack of round membrane envelopes around a central permeate tube Spiral-wound module - membrane is spirally wound, like a jelly roll, around the central collector tube Hollow fiber module - resembles a shell-and-tube heat exchanger

8 VOC Removal from N 2 /Air at Atmospheric Pressure by Permeation through a Hollow Fiber Module

9 Hollow Fiber Membrane Processes Vapor Permeation Two membranes: Plasma polymerized silicone on porous PP fiber O.D. with feed gas through the fiber bore Plasma polymerized silicone fibers containing VOC-selective absorbent in part of the pore inside the fiber

10 Advantages of Hollow Fiber-Based Membrane Systems Hollow fiber membranes are self supporting, commercial flat membranes must be supported in the modules Spirally wound modules are, per unit surface area, three times as expensive as hollow fiber membranes Hollow fiber membranes have two layers instead of three as in spirally wound modules Can achieve 10 times the surface area per module volume vis-à-vis spirally wound modules The process does not require a compressor, a vacuum pump alone is sufficient

11 Eliminate permeate side pressure drop through substrate in conventional operation mode. Easy scale-up; each fiber is separate. Gas flow pressure drop per fiber is not high at the flow rates leading up to 95-98% VOC removal in 45cm long modules. Possibility for pore condensation of VOCs. Any VOC liquid drop in feed gas will not damage the membrane; will be spread out rapidly by porous PP substrate. Ref: Cha et al., J. Membrane Sci., 128, (1997) Bhaumik et al., J. Membrane Sci., 167, (2000)

12

13 VOC R3 Separation Module 15 cm Diameter: 4 cartridges 10,000 Fibers/Cartridge 90 LPM

14 Key Features/Benefits of VOC-R3 System Removal Recovery - Reuse 98 %+ removal & solvent recovery potential Effective both for batch & continuous processes Suitable for steady/unsteady flow processes Compact devices Point of use Moderate capital cost Low operational cost No fire explosion risk

15 Sample Stream 1 To GC Sample Stream 2 To GC Gas Stream From Novartis Reactor (High VOC) Permeate Recycle Membrane Module Condenser Purified Stream (Low VOC) Vacuum Pump Liquid VOC

16 Modeling Equations for HF Modules ( ) Q ( Px, Py) im f p = πd ( Px Py lm f p ) d Lx dl δ m (7) Qim a ( bpx f ) δ = exp (8) m πd ap lm f L ( bpfx ) ( bpfx ) 2 l = x + f ln ! 2. 2! x x f W (9) a ln 1 ( Q / δ ) l L πd P ( Q δ N m f f lm f N m m) 2 2 ( bp x) ( bp x f f ) 2 l f = ln x +... /[ / ] 11.! 2. 2! x x f W (10)

17 Percent Removal of Toluene ( % ) Inlet Gas Flow (cc/min) : 27 : 60 : 100 : : : : Analytical : Simulation Feed Inlet Toluene Vapor Concentration ( x 103, ppmv) Figure 7. Variation of percent removal of toluene with feed composition. Feed: Toluene/N 2, Module 2, vacuum: 1Torr

18 VOC in Nitrogen/Air from Process Permeate Recycle Condenser Membrane Module Purified Nitrogen/Air Liquid VOC to Process Vacuum Pump

19 100 Percent removal of methanol Modules 2 Modules 1 Module Gas flow rate, slpm Methanol vapor removal at different feed gas flow rates. Membrane area in each module: 3.7 m 2 1 module; methanol concentration in feed gas: % 2 modules; methanol concentration in feed gas: % 3 modules; methanol concentration in feed gas: % Ref: Majumdar et al., J. Membrane Sci., 214, (2003)

20 100 Percent removal of toluene Module 2 Modules 3 Modules Gas flow rate, slpm Toluene vapor removal at different feed gas flow rates. Membrane area in each module: 3.7 m 2 Toluene concentration in feed gas: %

21 100 Percent removal of ethyl acetate Modules Gas flow rate, slpm Ethyl acetate vapor removal at different feed gas flow rates. Membrane area in each module: 3.7 m 2 2 modules; ethyl acetate concentration in feed gas: %

22 4 Cartridge Unit Tested at NASA Kennedy Space Center

23 Sample Stream 1 For Analysis Sample Stream 2 for Analysis Blower Contaminated Air Stream From the Paint Booth V V RM PG Membrane Module PG RM V V Membrane Bypass Line PG Purified Air Stream Back to the Paint Booth Permeated Air Stream to Condenser For VOC Recovery and Recycle of Noncondensibles to Feed Stream Vacuum Pump PG: Pressure Gauge; RM: Rotameter; V: Valve Figure 2. Experimental setup for VOC removal from a slipstream from the paint booth exhaust by hollow fiber vapor permeation membrane process.

24 Outlet VOC Concentration, ppbv Air Flowrate: 75.8 lpm Percent Removal Inlet VOC Concentration, ppmv Percent Removal of VOC Figure 6. VOC removal performance of NJIT-4 cartridge membrane module from a paint booth exhaust stream (permeate pressure: 2.8 cm Hg) Ref: Majumdar et al., J. Membrane Sci., 214, (2003)

25 Outlet VOC Concentration, ppmv Air Flowrate: 62.2 lpm Percent Removal Inlet VOC Concentration, ppmv Percent Removal of VOC Figure 7. VOC removal performance data from 2 cartridge set of NJIT-4 cartridge membrane module from a paint booth exhaust stream (permeate pressure: 2.8 cm Hg)

26 Outlet VOC Concentration, ppbv NJIT- 4 Cartridge Module Air Flowrate: 65.4 lpm Percent Removal Percent Removal of VOC Inlet VOC Concentration, ppmv 70 Figure 4. VOC removal performance of NJIT-4 cartridge membrane module from a paint booth exhaust stream at feed flow rate of 65.4 lpm (permeate pressure: 2.8 cm Hg)

27 Environmental Market: Air Treatment Hollow Fiber Membrane Module Systems 11/26/2007

28 NASA SKID VOC MEMBRANE UNITS 12 Cartridges per Housing Each Can Treat (255 LPM) Skid Scaled for 30CFM (850LPM)

29 Addition of Vacuum Pump

30 Add Metered Vent Stack

31 SKID FRAMING

32 Add Blower & Gas Couplings

33 ADD ELECTRICAL PANELS

34 Completed VOC Removal & Recovery System Hollow Fiber Membrane Based (600,000 Hollow Fibers) 11/26/2007

35

36

37

38

39

40 Thin ILM preparation Partial evaporation of pure or mixed solvents Solvent being studied: silicone oil Preparation of thin ILM: wet pores with hexane containing 30% silicone oil pull vacuum from shell side to remove hexane and pass N 2 on tube side

41 Thin ILM in the pores of the HF membrane Vacuum side: P y Interface: P x d 0 d l m d i Feed side: Px Ref: Obuskovic et al., J. Membrane Sci., 217, (2003).

42 Vacuum Plasmapolymerized PDMS coating Porous Polypropylene Support Vacuum Silicone oil Feed Air/N 2 + VOC A. Hollow Fiber B. Figure 1. Vapor permeation configuration using hollow fibers having a rubbery VOC-selective coating: A. Basic configuration with VOC-containing feed in fiber bore, vacuum on shell side and silicone coating on the outside surface; B. A thin layer of silicone oil in the pore next to the coating of configuration A.

43 Selectivity and N 2 flux Nitrogen Permeate Flux (gmol/cm 2 s)* Separatio n Facto r Feed Flow Rate (cc/min) Fe ed Flo w Rate (cc/ m in) Methanol run with ILM membrane C in : 0.92 % Methano l run w ith bare membranec in : 1.0 % Acetone run with ILM C in : 1.1 % Aceto ne run w ith bare membrane C in : 1.1 % Toluene run with ILM C in : 0.19 % To luene run w ith bare membrane C in : 0.19 % Membrane Area: 510 cm 2

44 Simulation Results for Methanol Methanol Outlet Conentration (ppmv) Experim ental Sim ulatio ns Experim ental Sim iulatio n Methanol inlet conc.: 9200 ppmv Methanol inlet conc.: 292 ppmv Fe e d Flo w Rate (cc/ m in) Ref: Obuskovic et al., J. Membrane Sci., 217, (2003).

45 Simulation Results for Toluene Toluene inlet concentration: 1953 ppmv To luene inlet co ncenratio n: 215 ppmv Toluene Outlet Concentration (ppmv) , Experim ental Sim u la tio n Feed Flow Rate (cc/min)

46 Simulation Results for Acetone Permeate Flow Rate (cc/min) VOC Outlet Concentration (ppmv) Feed Flow Rate: 100 cc/min Inlet Acetone Concentration: 9500 ppmv Permeate flow rate (cc/min) Membrane Area: 510 cm 2 Vacuum Level ~18.0 torr Vacuum Level ~1.0 torr VOC Outlet Concentration (ppmv) Elapsed Time (Days)

47

48 WFF VOC STREAM below 100ppm

49 AIR STREAM WITH ACETONE

50

51 AIR STEAM WITH TOLUENE

52

53 AIR STREAM WITH MEK

54

55

56 BIOFUEL MEMBRANES/Modules for Ethanol Separation & Recovery 11/26/2007

57 BIOFUEL MEMBRANES EUROPE BIOGAS PIPELINES Membranes/Modules for Biogas Upgrading 11/26/2007

58 NEXT STEPS Modify Membrane outer coating to enhance VOC Sorption Test Thinner ILM silicone oil layers for enhanced VOC Flux Test Effects of Temperature & Vacuum Levels in Field

59 Conclusions 1 Membrane Vapor Permeation Technique Using Plasma Polymerized Silicone on the Fiber Outside Surface with Feed Gas Flowing in the Bore has been Successfully Demonstrated in 4 Meter Square Cartridges 2 An Appropriate Nonvolatile Absorbent Liquid in Part of the thickness of the Pore Leads to Much Higher VOC Selectivity and Lower N 2 Permeation 3 VOC Removal Technology Using Membrane Modules and an Appropriate Absorbent Oil can Treat Low VOC-levels Emissions 4 However need to modify & optimize hollow fiber coatings and thickness of ILM silicone oil layer to treat below 1000ppm(v) VOC Levels when using modest Vacuum