Determination of fractional efficiency and loading of compressed air filters in overpressure up to 7 bar

Transcription

1 Determination of fractional efficiency and loading of compressed air filters in overpressure up to 7 bar Dipl. Ing. Martin Schmidt Palas GmbH Martin Schmidt 1

2 Introduction Potential objectives of the tester are e.g. Comparison of a filter according to the standard Comparison of a filter medium according to the standard Comparison of an inertial separator according to the standard Quality assurance of the production Reception inspection of the filter medium Optimisation of an existent filter New development of a separator Due to these different objectives, it makes sense for economical purposes to use different test systems. Martin Schmidt 2

3 Important parameters for filter testing The pressure drop run at the unused filter at different inflow velocities, the pressure drop run during dusting, the related dust storage capacity/drainage of the filter and, especially for the evaluation of the separation characterisation, the total separation efficiency or the fractional separation efficiency. For the determination of the fractional separation efficiency, which means the determination of the separation efficiency in dependence on the particle size, a particle counting and particle size measuring device, a so called optical aerosol spectrometer,is generally used. This measuring device has to be adapted to the respective application as to its device characteristics (e.g. the resolution, the classification accuracy, the maximum measurable particle concentration and the suction volume flow). Martin Schmidt 3

4 Standards for filter testing fractional efficency with optical aerosol spectrometers Application EN/DIN USA Standard ISO Room air filters EN 779 ASHRAE 52.2 Cleanroom filters HEPA / ULPA DIN EN Cabin air filters DIN E TS Engine air filters 5011/TS Vacuum cleaners DIN EN Coolant oil separators in preparation Compressed air filters Blow By The tables do not lay claim to completeness Martin Schmidt 4

5 Prescribed test aerosols for fractional efficency testing with optical aerosol spectrometers Standard Test aerosol Evaluation EN 779 DEHS 0.4 µm ASHRAE KCl Fractional efficiency DIN EN 1822 DEHS Fractional efficiency DIN EN A2 Fractional efficiency ISO KCl Fractional efficiency EN A2 Emission (mg/m 3 ) ISO/CD Oil Fractional efficiency Blow By Oil Fractional efficiency ISO 5011 A2 Fractional efficiency + gravimetry The tables do not lay claim to completeness Martin Schmidt 5

6 Total separation efficiency determination T 1 C C CLEAN RAW or T 1 M M CLEAN RAW Gravimetry, Photometry, Sodium flame test These methods are insensitive for high quality filters, e.g. filters better than 99.5 %, thus HEPA/ULPA quality. A photo meter signal depends on the particle size and particle concentration no clear information! Gravimetry is insensitive for small particle sizes and particle concentrations a million particles with the diameter 0.2 µm weigh as much as 1 particle of 20 µm. Martin Schmidt 6

7 Fractional efficiency determination Measuring methods: counting measuring methods Optical aerosol spectrometer Aerodynamic aerosol spectrometer SMPS System Martin Schmidt 7

8 ISO standards for counting measuring methods ISO : Determination of particle size distribution single particle light interaction methods, Part 1: Light interaction considerations ISO/CD : Light scattering aerosol spectrometer ISO/DIS : Light scattering airbone particle counter for clean spaces ISO/CD 15900: Electrical mobility analysis methods (SMPS) monodisperse aerosol (DMA) Martin Schmidt 8

9 Definition fractional efficiency T (x) 1 C C down (x) up (x) with: T(x) = fractional efficiency C up (x) = upstream concentration C down (x) = downstream concentration x = particle diameter The more accurate and reliable the particle size x and the correspondent particle concentration C upstream and downstream are measured, the more exact and reliable the separation curve can be determined. A reliable determination of the particle size x can only be realised by a high size resolution and a good size classification accuracy. The accurate determination of the particle concentration C up (x) is necessary! Martin Schmidt 9

10 HFP 2000 Horizontal filtermediatestrig Test of coalesure filter media High aerosol output with PLG 2000 H Drain (oil run off) with implemented reservoir after the filter media Exact particle detection with welas digital 2000 Horizontal filter media test rig HFP 2000 Determination of the fractional separation efficiency and examination of the loading with droplet aerosols dp 2 µm Martin Schmidt 10

11 HFP 2000 Horizontal filtermediatestrig Aerosol generation DEHS Air inlet up to 1000 l/min Automated test rig control welas digital control unit Filter holder with oil drain welas digital aerosol Sensor Pneumatic filter holder control Martin Schmidt 11

12 Test set up for the testing of compressed air filters Martin Schmidt 12

13 DFP 3000 Pressure air filter test rig Test pressure: up to 7 barg Volume air flow: up to 1000 Sl/min PLG 3000 DEHS aerosol generator for fractional efficiency testing AGF 3000 DEHS aerosol generator for loading Mass flow controllers for aerosol generation and main air flow welasdigital 3000 P measuring range: 0.2 µm (0.3 µm at 7 barg) 40 µm Mass flow controlled adjustment of sensor air flow Flat sheet media holder for pressure up to 1 barg Full automated test procedures with FTControl software Martin Schmidt 13

14 DFP 3000 Pressure air filter test rig DEHS aerosol generators PLG 3000 AGF 3000 Wall flow drainage Filter holder with oil drain Air inlet up to 1000 l/min Automated test rig control welas digital aerosol sensor Final filter welas digital control unit Martin Schmidt 14

15 Test set up DFP 3000 Air inlet Filter 10 x dhyd 6 x dhyd 6 x dhyd Liquid aerosol generator PLG 3000 AGF 3000 Sensor 1 for upstream Welas 3000 control unit Sensor 2 for downstream Test set up for welas 3000 systems: the two in one aerosol spectrometer Martin Schmidt 15

16 Definition fractional efficiency T (x) 1 C C down (x) up (x) with: T(x) = fractional efficiency C up (x) = upstream concentration C down (x) = downstream concentration x = particle diameter The more accurate and reliable the particle size x and the correspondent particle concentration C upstream and downstream are measured, the more exact and reliable the separation curve can be determined. A reliable determination of the particle size x can only be realised by a high size resolution and a good size classification accuracy. The accurate determination of the particle concentration C up (x) is necessary! Martin Schmidt 16

17 Aerosol generation in overpressure Martin Schmidt 17

18 Palas generators for aerosol generation under overpressure Palas aerosol generators according to VDI 3491 : Part 5: nebuliser with binary nozzle AGF 2.0 D / AGF 10.0 D AGF 3000 PLG 2000 H (Laskin) PLG 3000 Part 9: aerosol generation with a brush feeder RBG 1000 pressure resistant Martin Schmidt 18

19 RBG 1000 Aerosol generation with the brush feeder Application areas: Filter testing Fractional efficiency measurements Gravimetric separation degree measurements Loading measurements Particle size analysis Flow visualisation Dispersion against over /underpressure up to 3 bar Calibration of particle measuring devices Dosing of monolithic solids, e. g. chalk RBG 1000 according to VDI 3491, sheet 9 Martin Schmidt 19

20 Operating principle of the RBG Series dispersion air dispersion head aerosol brush powder powder reservoir transportation piston feed Martin Schmidt 20

21 Mass flows RBG Series The following mass flows result for the RBG from the geometrical dimensions of the powder reservoir and the feed speed in case of a feed density of 1 g/cm³. RBG-1000 Piston diameter 7 mm 10 mm 14 mm 20 mm 28 mm RBG mm 32 mm Feed quantity 3,1 g 6,3 g 12,3 g 25,1 g 49,2 g 30 g 144 g Feed 1 mm/h Feed 5 mm/h Feed 700 mm/h 38 mg/h 79 mg/h 154 mg/h 324 mg/h 616 mg/h 0,2 g/h 0,8 g/h 190 mg/h 395 mg/h 770 mg/h 1620 mg/h 3080 mg/h 1 g/h 4 g/h 27 g/h 55 g/h 107 g/h 219 g/h 430 g/h 140 g/h 562 g/h Feed quantity = piston cross sectional area * powder reservoir length * feed density Mass flow = piston diameter * feed * feed density Martin Schmidt 21

22 AGF 2.0 D / AGF 10.0 D pressure resistant up to 10 bar Aerosol generator for the nebulisation of liquids and suspensions with constant particle rate and defined particle spectrum. Known and reproducible particle size distribution by means of cyclone. Constant particle rate. Variable particle generation rate by the use of micrometer screw. High particle concentration. Different particle size distributions by means of different cyclones. Long dosing time. Martin Schmidt 22

23 PLG 3000 pressure resistant up to 7 barg Aerosol generator for the nebulisation of liquids and suspensions with constant particle rate and defined particle spectrum. Fractional efficiency testing of pressure air filters up to an overpressure of 7 barg Extremely constant particle rate Variable particle generation rate by air flow adjustment with Mass flow controller Particle mass from approx. 0.1 g/h up to 2.4 g/h Easy to refill Long dosing time. Martin Schmidt 23

24 AGF 3000 pressure resistant up to 7 barg Aerosol generator for the nebulisation of liquids and suspensions with constant particle rate and defined particle spectrum. Loading of pressure air filters up to an overpressure of 7 barg Extremely constant particle rate Variable particle generation rate by air flow adjustment with Mass flow controller Dosing unit Particle mass up to approx. 1.2 Kg/h Automatic refill unit Long dosing time by large tank (12 l) Liquid tank Martin Schmidt 24

25 Set up and function of the aerosol spectrometer welas during aerosol measurements in overpressure Martin Schmidt 25

26 Martin Schmidt 26

27 Unique characteristics welas digital and Promo welas digital 2000 Promo 2000 welas digital 3000 Promo Signal transmission sensor Control unit via optical fibres + Patented modular system with replacableaerosol sensors + Measurement range 0.2 µm up to 40 µm (100 µm) + Max. concentration up to 10 6 P/cm³ + Temperature range from 120 C up to > 470 C + Pressure tight up to 10 barg + White light source and 90 scattered light detection: clear calibration curve + Patented T aperture technology: Measurements without border zone error + New signal processing electronics coincidence detection at each individual signal Evaluation with high temporal resolution of 10 ms + New logarithmical AD converter + Higher countingefficiency for nano particles + High resolution and excellent sizing accuracy Martin Schmidt 27

28 Setup welas digital 3000 Similar equipment characteristics welas digital control unit Scattered light from sensor 1 and sensor 2 is transmitted alternating via fibre optic cable to the same photomultiplier. welas digital light source Transmission of light to sensor 1 and sensor 2 via optical fibre. The sampling volume flows are adjusted with the same pump. Two devices in one! aerosol sensor 1 welas aerosol sensor 2070 welas aerosol sensor 2100 welas aerosol sensor 2200 welas aerosol sensor 2300 welas aerosol sensor 2500 aerosol sensor 2 welas aerosol sensor 2070 welas aerosol sensor 2100 welas aerosol sensor 2200 welas aerosol sensor 2300 welas aerosol sensor 2500 Martin Schmidt 28

29 Overview on the current sensors aerosol sensors C max [P/cm 3 ] measuring ranges [µm] welas * 0,12-3,5 0,2-10 0, ,6-40 welas * 0,12-3,5 0,2-10 0, ,6-40 Series 1000 optionally available: pressure-tight up to 10 bar (sensor type ending P) and heatable up to 250 C (sensor type ending HP) (470 C optionally) welas * 0,2-10 0,3-17,5 0,6-40 welas * 0,2-10 0,3-17,5 0,6-40 welas * 0,2-10 0,3-17,5 0,6-40 welas * 0,2-10 0,3-17,5 0, welas * 0,3-17,5 0, Series 2000 optionally available: pressure-tight up to 10 bar (sensor type ending P) temperature: C and heatable up to 250 C (sensorr type ending HP) Special sensor welas 27300* * --- 0,5-17, Sensor optionally available: heatable up to 250 C (sensor type ending H) T>470 C on demand! Sensor for particles in liquids C max [P/ml] measuring ranges [µm] welas 2100 FL ,7-40 µm *Only in combination with the welas digital system. For the former welas system, C max has to be divided by 5. The sensors of series 1000 canbecombinedwiththewelas digital 1000 system The sensors of series 2000 and can be combined with the welas digital 2000/3000 system and Promo. Martin Schmidt 29

30 Test set up DFP 3000 Air inlet Filter 10 x dhyd 6 x dhyd 6 x dhyd Liquid aerosol generator PLG 3000 AGF 3000 Sensor 1 for upstream welas 3000 control unit Sensor 2 for downstream Test set up for welas 3000 systems: the two in one aerosol spectrometer Martin Schmidt 30

31 Set up of the sensors for measurement in overpressure and temperatures up to 250 C Aerosol inlet Aerosol outlet Heating elements and thermal insulation Protection glass for optics Optical lenses + Free aerosol flow in order to avoid particle separation + Heatable up to 130 C or 250 C in order to avoid condensation of the gas components. + Pressure resistant up to 10 bar + Replaceable protection glasses for the optical lenses + Resistant against chemical aggressive media due to selection of appropriate materials, e. g. hastelloy Martin Schmidt 31

32 Measurement of the particle concentration c N N counted particles V actual N Particlenumber / time V operation volume flow depending onp, T c ist N Particlenumber concentration Adjustment or regulation of the volume flow through the sensor: Automatically via mass flow controller. Measurement of temperature and pressure in order to calculate the operation volume flow Additonally: Measurement of the particle velocity in the measurement volume by means of the scattered light signal Martin Schmidt 32

33 Fractional efficiency of filter cartridge at different face velocities Conclusion Martin Schmidt 33

34 Conclusion 1 Compressed air filters can be tested even under pressure easily and reliably. with dust up to 3 bar with oil droplets up to 10 bar The aerosol technological components aerosol generator dilution system aerosol spectrometer have to be clearly characterised. Martin Schmidt 34

35 Conclusion 2 Palas has a long time experience in building filter test systems and also upgrading them with particle measuring technology. We have manufactured and sold worldwide 75 complete test rigs! Clearly defined components of particle measurement technology and the proof of their function make it possible to test oil separators quickly, reliably and under real life conditions. The components a already used by several customers for the testing of compressed air filters. The described test methods enables the user to compare several Compressed air filters and also to optimise them reliably and economically with a high repeatability and a high reproducibility. Martin Schmidt 35