technische universität dortmund Fakultät Bio- & Chemieingenieurwesen Mechanische Verfahrenstechnik

Transkript

1 , thermal equilibrium and the measurement of dust resistivity D. Pieloth, P.Walzel PiKo Workshop MPI for Polymer Research / 30th September 2011 Fakultät Bio- & Chemieingenieurwesen Mechanische Verfahrenstechnik

2 Outline Electrostatic precipitators and dust resistivity Electrostatic precipitators (ESP) Dust resistivity Dust resistivity measurement Experimental setup Particle diameter and dust resistivity Thermal equilibrium and the measurement of dust resistivity New measurement chamber Particle layer stripping measurement Summary and Outlook 2

3 Electrostatic precipitator (ESP) Dust deposition pattern within an electrostatic precipitator 3

4 Dust resistivity Decrease of E-Field strength in electrostatic participator due to voltage drop within the dust layer I = electric current ρ = resistivity s = layer thickness A = area of collecting electrode j = current density Back discharge of already absorbed dust particles Back corona due to overriding the E-Field strength within the dust layer Drop of separation efficiency of a ESP Measurements indicate that adsorption and desorption of moisture from the gas play a dominant role! (Adhesion forces, conductivity) 4

5 Measurement of dust resistivity Experimental setup 5

6 Measurement of dust resistivity Electrode arrangement 6

7 Particle diameter and dust resistivity Particles used in dust resistivity measurement 7

8 Dust resistivity measurement T/ t 3 C/min 8

9 Dust resistivity measurement T/ t 3 C/min 9

10 Dust resistivity measurement (mechanical hysteresis) Gas enters the pores Gas Fluid Gas pressure p V f = Fluid Volume V ε = Gap Volume Saturation S 10

11 Dust resistivity measurement x p = µm, T d = 40 C, T = 100 C ( via T 2 (t) > T 1 (t) ) 0,6 0,5 0,4 I / µa 0,3 0,2 0,1 0,0 13:30 13:37 13:44 13:51 13:58 14:06 14:13 14:20 14:27 Time Thermal equilibrium and the measurement of dust resistivity 11

12 Dust resistivity measurement x p = µm, T d = 40 C, T = 100 C ( via T 2 (t) > T 1 (t) ) I / µa 0,60 0,50 0,40 0,30 0,20 0,10 0,00 13:25 13:39 13:53 14:08 14:22 14:37 Time Thermal equilibrium and the measurement of dust resistivity 12

13 Dust resistivity measurement x p = µm, T d = 40 C, T = 140 C ( via T 2 (t) < T 1 (t) ) 0,7 0,6 0,5 I / µa 0,4 0,3 0,2 0,1 0,0 16:12 16:19 16:26 16:33 16:40 16:48 16:55 Time Thermal equilibrium and the measurement of dust resistivity 13

14 Dust resistivity measurement Measurement of adsorption and desorption velocities of moisture from gas: Institut für Nichtklassische Chemie e.v. Zentrum für Sorption und Reaktion an Feststoffen D Leipzig Consequences:? New measurement standard for dust resistivity? 14

15 Schematic of particle stripping measurement Adhesion of dust particles on the top layer of dust, detection of release of those particles into gas stream air + stripped particles air air Grimm Aerosol Spectrometer Measurement chamber Back discharge of dust under defined air conditions 15

16 Summary and Outlook New dust resistivity measurement chamber build Long-run (in time for a given temperature, dew point, etc.) measurements show a change of dust resistivity with time Particle layer stripping measurement under defined air conditions will start soon (testing a Aerosol Spectrometer) Thanks to DFG for the financial support Thank you for your attention! 16