Sample Conditioning Instruments. Jonna Kannosto Technical Marketing Specialist, PhD

Transcription

1 Sample Conditioning Instruments Jonna Kannosto Technical Marketing Specialist, PhD

2 Dekati Solutions: Complete setups It s not only the source or measurement instrument! It s also how to take a proper sample! + + Source + Sampling line + diluters + Measurement instrument Can be - Losses - Particle changes Jonna Kannosto

3 ? How to take a sample Sample needs to represent the source Particle concentration Particle size Particle composition Sample needs to be transported to measurement device Sample should remain the same during the transportation Device must be able to measuring the relevant quantity of particles

4 Hot sample and high concentration Instruments cannot measure too high concentrations or hot samples Dilution Lower gas and particle concentrations Lower temperature No usually High vapor and particle concentration Hot sample Source + Sampling line and + system Measurement instrument Jonna Kannosto

5 Content Sample conditioning What happens in dilution How to dilute Sampling without dilution Why and when? Sample conditioning devices Dekati Diluter, DI-1000 Dekati Engine Exhaust Diluter, DEED Dekati Fine Particle Sampler, FPS-4000 Dekati Axial Diluter, DAD Dekati Cyclones Dekati Thermodenuder

6 Sample conditioning What happens in dilution?

7 Sample conditioning Things you need to know! Sampling dynamics Nucleation Condensation Evaporation Coagulation Effect of dilution parameters Temperature Residence time Humidity Dilution ratio Particle Losses Inertial Gravitational Turbulent Diffusion Thermophoretic Electrophoretic Jonna Kannosto

8 Sampling Dynamics Nucleation New particles are formed Particle concentration increases Condensation Vapor condense on surfaces and particles Particle composition changes and increases, water and moisture problems in sampling lines and measurement instruments Evaporation Volatile material evaporates from particles Particle composition changes, size decreases and particle number concentration may decrease Coagulation Two particles hit each other and formed a one new particle Particle concentration decreases, size increases and composition changes Jonna Kannosto

9 Sampling Dynamics Particles can be lost easily Number concentration decreases Size distribution changes Mechanisms Inertial Gravitational Turbulent Diffusion Thermophoretic Electrophoretic Particle losses Jonna Kannosto

10 Inertial impaction Problem large particles are removed through impaction to sampling line walls Solution straight sampling line or flow volume vs. line diameter Particle number size distribution changes and concentration decreases Jonna Kannosto

11 Gravitational losses Problem removes large particles by gravitational settling Solution short sampling lines, avoid long horizontal sections and residence time Particle number size distribution changes and concentration decreases Jonna Kannosto

12 Diffusion losses Highly dependent on particle size, larger for small particles Problem small particles deposit through diffusion to sampling line walls Solution short sample transfer lines, laminar flow and short residence time Particle distribution changes and concentration decreases Main reason why PM exhaust samples cannot be stored

13 Diffusion losses Effect is highly dependent on particle size

14 Thermophoretic losses Problem - all particles are driven along a decreasing temperature gradient in gas Magnitude dependent on temperature gradient and residence time Solution sample transfer line walls must be at sample temperature or higher Jonna Kannosto

15 Effect of thermophoretic losses Effect not dependent on particle size for small particles For large particles dependent on particle heat conductivity

16 Electrostatic losses Problem - charged particles are driven to sampling line walls due to electric fields Solution - use conductive material e.g. metal pipes. NO Teflon or silicon sample transfer lines or connectors Depends on charge/diameter ratio. If particles are uniformly charged depends on particle size, but generally this is not the case

17 Re-entrainment Problem - large particle clusters and volatiles re-entrain from sampling line walls Solution - avoid losses and keep your sampling lines clean and use cyclone ati Ltd.

18 Losses - conclusions Transfer lines must be designed to suit the sample Minimise length Minimise residence time Correct and preferably constant temperature of sample transfer lines Conductive sample transfer lines Watch out for re-entrainment - sensible use of sample transfer lines Minimise the losses Use cyclone

19 Sample conditioning How to dilute?

20 Dilutions and sample Uncontrolled dilution Vapours on particle surfaces or forming new particles Adsorption with denuder Stripping vapours DEED Dekati Double Diluter, FPS Hot dilution Lower vapour pressure (lower dew point) At exhaust temperature Cold dilution Lower concentration Lower temperature Cold dilution FPS High nucleation tendency

21 Dilutions Hot sample Measure the sample as it is 1. Two state: hot-cold dilution 2. Preventing condensation 3. Sampling without dilution Adsorption with denuder Stripping vapours Hot dilution Lower vapour pressure (lower dew point) DEED Dekati Double Diluter, FPS At exhaust temperature Cold dilution Lower concentration Lower temperature

22 Two-state dilution Sample cooling without dilution causes unwanted artefacts and losses High temperature, high water content sample is usually treated with controlled (heated) dilution - Decrease of temperature, particle and volatile material concentration - Typically two-stage dilution, min. dilution ratio ~1:20 - No condensation Hot dilution Lower vapour pressure (lower dew point) At exhaust temperature Cold dilution Lower concentration Lower temperature Jonna Kannosto

23 Two-state dilution Uncontrolled dilution Vapours on particle surfaces or forming new particles Solid particles are measured Controlled dilution setup Hot dilution Evaporation chamber Cold dilution DEED DEED AIR Lower vapour pressure (lower dew point) At exhaust temperature Catalytic stripper Lower concentration Lower temperature Jonna Kannosto

24 Preventing condensation of volatiles Uncontrolled dilution Vapours on particle surfaces or forming new particles Adsorption with denuder Stripping vapours Solid particles are measured Do not use thermodenuder for water vapor!! Jonna Kannosto

25 Sampling without dilution Why and when?

26 Sampling without dilution High temperature, high water content sample If there is low particle concentration Dilution is not option Hot Sample But low particle number concentration Jonna Kannosto

27 Sampling without dilution Dilution may not be possible at low concentrations instrument can not measure too low concentrations Solution is to measure undiluted hot sample with heated instrument Hot Sample But low particle number concentration Hot dilution Cold dilution Not enough particles to be able to measure Jonna Kannosto

28 High Temperature ELPI+ Hot Sample Can be measured without dilution Jonna Kannosto

29 Summary: dilution solutions No dilution no unwanted condensation or nucleation Uncontrolled dilution Vapors on particle surfaces or forming new particles Hot dilution Controlled dilution setup Evaporation chamber Cold dilution Adsorption with denuder Stripping vapours DEED Dekati double diluter FPS

30 Content Sample conditioning What happens in dilution How to dilute Sampling without dilution Why and when Sample conditioning devices Dekati Diluter, DI-1000 Dekati Engine Exhaust Diluter, DEED Dekati Fine Particle Sampler, FPS-4000 Dekati Axial Diluter, DAD Dekati Cyclones Dekati Thermodenuder

31 Dekati Diluter and Double Diluter

32 Dekati Diluter Dilution Air Exhaust Air SAMPLE IN SAMPLE OUT Low pressure caused by dilution air flow in the nozzle sucks the sample from the inlet Mixing in the mixing chamber Coaxial dilution, low losses

33 Dekati Double Diluter Setup Tailpipe: - High concentration - High temperature - High vapor pressure Hot Dilution - Concentration decrease - Vapor pressure decrease - Temperature preserved Or with any instrument Cold Dilution: - Concentration decrease - Low vapor pressure => safe temperature decrease

34 Double Diluter setup ~7 lpm Sample in 1. diluter and heater 2. diluter 0-60 lpm Sample out Pressurized air heater Purifying setup

35 DEED Dekati Engine Exhaust Diluter Dekati Ltd.

36 DEED Dekati Engine Exhaust Diluter Particle reduction factor Low ~100 High ~1000 Dilution system extremely robust - all stainless steel and no moving parts All specifications as recommended by PMP group Simple user interface Can be used with ANY particle number or mass measurement device

37 DEED Operation ~7 lpm 0-60 lpm Dilution air 120 slpm

38 Calibration Calibration done according to PMP specifications Evaporation efficiency determined with tetracontane

39 Dekati FPS Dekati Fine Particle Sampler

40 FPS: Fine particle sampler Properties Controllable Dilution temperature cold/hot 0-250(350) C Dilution ratio 1:20(10)-1:200 Residence time Residence time chamber & dilution ratio Measurements from low/high Temperature C Pressure mbar abs Trap studies Continuous dilution ratio calculation +/- 10% reading Data recording Integration to data logging systems Analog outputs/inputs

41 FPS Operation Principle Primary dilution perforated tube dilution Cold or hot primary dilution Controlled dilution ratio Secondary dilution Ejector type diluter acts as pump Cooling of sample Controlled dilution ratio

42 FPS software: FPSVI Can be operated with Laptop Data Recording Temperature and pressure monitoring Dilution ratio control Heater/Cooling control Flush

43 FPS ELPI+ Setup for Stack Sampling Dekati Fine Particle Sampler Heated setup Dekati ELPI+ For continuous particle size distribution and concentration measurement Laptop for unit control - optional

44 FPS conditioning setups for stack sampling FPS-4000 FPS-4503 For any source Heated/cooled dilution DR 1:20 1:200 Normally supplied with 2.5 micron cyclone Can be used also without the cyclone

45 Dekati Axial Diluter DAD-100

46 DAD-100 operation principle 1-30 lpm Depends on dilution ratio and instrument flow rate lpm 1-3 lpm typical) Low particle losses

47 DAD-100 Simple dilution tool for any aerosol sample Measurement instrument inlet flow needs to be known No problem with Dekati products Adjustable, but constant dilution ratio Calibrated Up to 1/10 dilution ratio Low dilution air consumption, 1 30 lpm Calculation sheet provided with instrument

48 Dekati Cyclones SAC-65 FPS-cyclone

49 Dekati Cyclone SAC-65 Pre-separator with 10μm cutpoint at 10 lpm Stainless steel construction Designed according to EPA 201A Can be used in temperatures up to 600 C Accessories include heaters for use outside stack Excel sheet for exact cut point calculation

50 Pre-separator Recommended to use pre-separator if Concentration of particles >10 µm is high Sampling line is long and horizontal due to re-entrainment Dekati Cyclones SAC-65 Cut-size 10 µm for 10 lpm 20 C/1013 mbar Port size 150 mm Isokinetic nozzles for 2-18 m/s gas flows FPS-cyclone Cut-size 2.5 µm for 8 lpm 20 C/1013 mbar Port size 100 mm Isokinetic nozzles for 4-25 m/s gas flows

51 Dekati Thermodenuder

52 Design of Dekati Thermodenuder Heats exhaust gases up to 250 C most volatile components evaporate in vehicle exhaust Removes VOC with fibrous active carbon High volume flow rate, LPM Active carbon Cooling air Cooling in Sample out Cooling out Heater Sample in

53 Denuder section Hydrocarbon vapours Particles Temperature decreases Activated char coal Adsorbed vapour

54 Content Sample conditioning Dilution options Sampling without dilution Why and when? Sample conditioning devices Dekati Diluter, DI-1000 Dekati Engine Exhaust Diluter, DEED Dekati Fine Particle Sampler, FPS-4000 Dekati Axial Diluter, DAD Dekati Cyclones Dekati Thermodenuder

55 Excellence in Particle Measurements