Short introduction to molecular filtration


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An introduction to Molecular Filtration and its use to filter out gas phase contaminants from HVAC and process plant systems. Filter performance and energy efficiency need to be considered

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Short introduction to molecular filtration

  1. 1. C L E A N A I R S O L U T I O N SWelcome to the Camfil Farr Training AcademyAn introduction to Molecular Filtration and its use to filter outgas phase contaminants from HVAC and process plantsystems. Filter performance and energy efficiency need to beconsidered. © CAMFIL FARR 11-03-28 1
  2. 2. C L E A N A I R S O L U T I O N S Low Energy Air Filters Production Facility ● Sales Office ● Agent ● Head Office ● © CAMFIL FARR 11-03-282010 global sales £430 million24 Production Plants, 4 R&D Centres 23400 employees
  3. 3. C L E A N A I R S O L U T I O N S Camfil Farr Training Academy Webinar Programme 2011 Attend a free Camfil Farr Webinar from the comfort of your own office Every Friday at 11am GMT Register at webinar programme is aimed at assisting you with your business processes demonstrating how substantial energy saving opportunities can be made. Each Webinar lasts no more than 30-45 minutes and is free of charge.
  4. 4. C L E A N A I R S O L U T I O N S What is Molecular Filtration?• Most air filtration applications concern the removal of particles (dust).• However......• We can also remove gases and vapours from the air• Camfil Farr call this Molecular Filtration – Because we remove individual molecules Issue CE/1 July 2007• Molecular = Gas phase = Carbon = Chemical FILTRATION. 4
  5. 5. C L E A N A I R S O L U T I O N S How do molecular pollutants affect us?• 1. Smell / odour • 2. Irritants – Food smells – Onions – Waste water treatment – Ozone – Traffic fumes – Ammonia – Aviation fuel • 4. Corrosion• 3. Poison / toxic – Acidic gases in paper mills etc – Nuclear power – radio – Acidic gases in museums isotopes – Isocyanates in foam Issue CE/1 July 2007 production – War gases 5 – Dioxins
  6. 6. C L E A N A I R S O L U T I O N SWhat is the scale of molecular filtration?• Molecules are 1,000 to 10,000 times smaller than the MPPS removed by HEPA filters.• There are many, many, many more molecules in the air than particles.• Avogadros number - 6.022 x 1023 molecules per mole (molecular weight in grams) – 34 g of hydrogen sulphide occupies 22.4 litres – (602,200,000,000,000,000,000,000 molecules)• Particle filters will not remove molecules, we need to use something different – We exploit a technique called: Adsorption – We mostly use: Activated carbon
  7. 7. C L E A N A I R S O L U T I O N S What is an adsorbent ? How does it filter?• Activated carbon is full of holes or pores and has a very high internal surface areas – more than 1000 m2/gram• Activated alumina is also porous, but has a much lower surface area (150-250 m2/g)• Molecules diffuse from the external air and become trapped on the internal surface of the pores. Issue CE/1 July 2007 7
  8. 8. C L E A N A I R S O L U T I O N S SEM images of activated carbon Issue CE/1 July 200750% pores, 50% carbon, different size pores (we cansee only the very big ones with SEM), the very highsurface area is in the small invisible pores 8
  9. 9. C L E A N A I R S O L U T I O N SHow does carbon work? - Peg board analogy• Carbon can be compared to a peg-board toy.• High internal surface area with many active sites where molecules can be adsorbed. – holes where pegs can be placed © CAMFIL FARR 11-03-28• The number of active sites is huge! 9
  10. 10. C L E A N A I R S O L U T I O N S How does carbon work? - Peg board analogy• Carbon will adsorb many different molecules, (tens of thousands) – Different colour pegs• Broad spectrum adsorption• A very limited number of molecules are not adsorbed – Green pegs © CAMFIL FARR 11-03-28• Less than 50 different molecules 10 – True gases (B.Pt << 0 deg. C)
  11. 11. C L E A N A I R S O L U T I O N SHow does carbon work? - Peg board analogy• Adsorption continues until all actives sites are occupied. – There is a peg in every hole – Zero residual capacity• Efficiency gradually reduces because the probability of finding an unoccupied site © CAMFIL FARR 11-03-28 decreases. 11
  12. 12. C L E A N A I R S O L U T I O N SHow does carbon work? Peg board analogy• Carbon surface can be pre- treated with a chemical –• Impregnated carbon• Chemical is chosen to target a single molecule or group of related molecules.• Impregnated carbons adsorb © CAMFIL FARR 11-03-28 the gases missed by broad spectrum carbon.• e.g. hydrogen sulphide, ammonia, mercury vapour, war gases, hydrogen 12 cyanide, formaldehyde
  13. 13. C L E A N A I R S O L U T I O N SWhy is Broad spectrum adsorption so important? • Man has invented approx 100,000 chemicals – Never pre-existed in nature • Most of these are now in the air to some degree • Who can identify and measure all of these? • Use a Broad Spectrum Adsorbent with confidence – > 99% of all different molecules will be adsorbed © CAMFIL FARR 11-03-28 – VOCs, hydrocarbons, solvents etc. • Suitable for vapours (Boiling Point greater than 70 deg C) • Suitable for vapours (Vap.Press.below 100 mm Hg at 20 deg C) 13
  14. 14. C L E A N A I R S O L U T I O N SThese gases cannot be treated by adsorption:• Carbon monoxide CO• Carbon dioxide CO2• Methane CH4• Nitrogen oxide NO• Hydrogen H• Helium He2• Radon Rn Issue CE/1 July 2007These molecules are too small and too un-reactive 14
  15. 15. C L E A N A I R S O L U T I O N SDesign considerations• Adsorbent selection and contact time – Determines the efficiency and how effectively media is used.• Particle / Granule size – Effect on efficiency and pressure loss (energy cost)• Elimination of leaks – Inside the filter and between filter and housing• Even air distribution across all filter media © CAMFIL FARR 11-03-28• A well designed / constructed molecular filter is a high efficiency device – 95.0 to > 99.95 % 15
  16. 16. C L E A N A I R S O L U T I O N SFactors affecting performance : contact time Contact time (sec) = volume of media (m3) volumetric flow rate (m3/s) A minimum contact time is needed to allow for.. 1) Diffusion and adsorption processes, Broad Spectrum carbon > 0.1 seconds 2) Chemical reaction Impregnated carbon > 0.2 seconds © CAMFIL FARR 11-03-28 Cutting back on contact time is a false economy 16
  17. 17. C L E A N A I R S O L U T I O N S Factors affecting performance• Increasing temperature: – Broad Spectrum carbon: efficiency and capacity decreases – Normal upper limit – 40 to 50 deg C – Impregnated carbon and impregnated activated alumina: efficiency increases © CAMFIL FARR 11-03-28 – Normal upper limit - 100 deg C 17
  18. 18. C L E A N A I R S O L U T I O N S Factors affecting performance• Increasing relative humidity: – Broad spectrum carbon: efficiency and capacity decrease – Competition for active sites, blocking of micropores – Normal upper limit is 70% to 80% – Impregnated carbon and impregnated activated alumina – © CAMFIL FARR 11-03-28 optimum range 60% to 90% – Presence of water essential for chemical reactions 18
  19. 19. C L E A N A I R S O L U T I O N Sfactors affecting performance:- particle size © CAMFIL FARR 11-03-28 19
  20. 20. C L E A N A I R S O L U T I O N SComfort / IAQ (protecting people)note: there are internal and external sources of molecular pollutants • City centre office buildings – Traffic fumes, general IAQ • Airports – Aviation fuel, diesel fumes • Hotels • Schools • Offices in industrial areas Issue CE/1 July 2007 20
  21. 21. C L E A N A I R S O L U T I O N S Typical Products: Comfort City Family – perfect for IAQ issues • Camcarb• Citycarb – – Traditional heavy duty solution – Combination particle and molecular filter using granular or pellet carbon. – Uses Rapid Adsorption Dynamics (RAD) – Metal and Green versions• Citysorb – Very high initial efficiency – Molecular filter only – Uses RAD – Very long lifetime• CityFlo – Combination particle and molecular filter – A member of the Hi-Flo family Issue CE/1 July 2007 21
  22. 22. C L E A N A I R S O L U T I O N SClean Process (protecting processes, equipment, artefacts)• Microelectronics – Acids, bases, VOCs• Pulp and paper, petrochemical – Acidic gases• Museums / art galleries – Acidic gases, ozone• IVF laboratories Issue CE/1 July 2007 – Formaldehyde, VOCs 22
  23. 23. C L E A N A I R S O L U T I O N STypical Products: Clean Process• Camcarb • Campure – Heavy duty solution using – Corrosion Control (acidic gases) granular or pellet carbon. – Excellent for process applications – Pulp and Paper, Petrochemical • Gigapleat• Camsure panels – Focussed on microelectronics – Very versatile solution Issue CE/1 July 2007 23
  24. 24. C L E A N A I R S O L U T I O N S Safety and Protection (protecting the environment)• Nuclear power generation – Radioactive gases• Nuclear fuel production – Hydrogen fluoride• Manufacture of polyurethane foam – Isocyanates• Waste handling – Odours (1000,s of different molecules)• Chemical manufacture – Toxic chemicals and odours• Military applications Issue CE/1 July 2007 – war gases• Pharmaceutical – control of drugs and odours 24
  25. 25. C L E A N A I R S O L U T I O N S Typical products: Safety and Protection• Acticarb 4000 • Camcarb – Nuclear power – Heavy duty solution using – Very low leakage rate granular or pellet carbon. – Individually tested – Excellent for process applications• Annular Bed Carbon Filter (ABC) – Industrial solution• Vertical Deep Bed Filter (VDB) – Industrial solution• Deep Cell Adosrption Filter (DCAF) • Camsure panels – Very versatile solution Issue CE/1 July 2007 25
  26. 26. C L E A N A I R S O L U T I O N SMolecular filtration in a ventilation system• Outside air (make-up) • Recirculation air• Highest concentration of external • Control of internal source pollutants pollutants. (low concentrations)• No effect on internal sources. • Residual external pollutants.• One-pass operation. • Multi-pass operation• High efficiency. • Moderate to high efficiency.• Long life. • Long life• Low pressure drop • Low pressure drop• Traditional solution with high weight • Contemporary solution with Rapid © CAMFIL FARR 11-03-28 of granular adsorbent Adsorption Dynamics (RAD) 26
  27. 27. C L E A N A I R S O L U T I O N S Case Study One Control of domestic rubbish odours (Spain)• New housing developments • Odour removal efficiency proved by• Domestic rubbish conveyed olafactometry (EN13725) pneumatically through underground • Now ~ 50 installations, inc Dubai pipes. • Carbon replacement every 12-24• Smell problem at remote collection months centre.• Air sampling used to identify 100 most prevalent gases (GC / MS)• Solution based on broad spectrum adsorption. © CAMFIL FARR 11-03-28 27
  28. 28. C L E A N A I R S O L U T I O N S Case Study Odour control – Pharmaceutical Plant (UK)• Customer invented new drug molecule. • Conclude – a suitable solution is available• Extreme odour problem during • Conclude – very high chance of success production. • Conclude – very little risk. – Molecule has mercaptan function -SH • Customer accepts Camfil proposal and risk• assessment. Factory is in middle of residential area. • Camfil install leak-free carbon filter.• No-one has any experience – new • Dual impregnation system to target molecule. mercaptan group• Camfil make study of chemical and – Acidic characteristic and sulphur atom physical charcteristics of molecule and • 0.3 second contact time compare to known related molecules. • Complete removal of odour in exhaust air © CAMFIL FARR 11-03-28• Comparison made to existing installations in similar applications. 28
  29. 29. C L E A N A I R S O L U T I O N SCase StudyA true story (Part One) © CAMFIL FARR 11-03-28 29
  30. 30. C L E A N A I R S O L U T I O N SCase Study FourA true story (Part Two) © CAMFIL FARR 11-03-28 30
  31. 31. C L E A N A I R S O L U T I O N SCase Study FourA true story (Part Three) © CAMFIL FARR 11-03-28 31
  32. 32. C L E A N A I R S O L U T I O N SCase Study FourA true story (Part Four) © CAMFIL FARR 11-03-28 What can we learn from this story? 32
  33. 33. C L E A N A I R S O L U T I O N S THANK YOU for attending this webinar session ANY QUESTIONS? Please do not hesitate to contact Camfil Farr for any additional information or to arrange a visit.For more information about clean air solutions, improving air quality, low energy air filters, CRC (Carbon Reduction Commitment), AHUs (Air Handling Units) and the EPBD, visit the blog and subscribe to the RSS Feed 33