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The retention potential of stuffed filtering cartridges from dust measurement in condensing

flue gas

Manuel Schwab ; Elisabeth Wopienka; Markus Schwarz; Christoph Schmidl

2010, Expert Workshop Dust measuring procedures for small biomass furnaces, Leipzig

Abstract

Cartridge filters, stuffed with quartz fibre wool, are used for the gravimetrical determination of

particulate matter emission in flue gases of combustion systems. In condensing flue gases the

standard VDI 2066 prescribes an outstack measurement including a trace heating. The determination

of particulate matter emission below 50 mg/Nm³ requires furthermore a secondary filter downstream

the measurement. This work focus on the retention potential of stuffed filtering cartridges for a

particulate matter emission higher than 50 mg/Nm³. The influence of the packing density and of a

condensing flue gas is surveyed. Overall 78 dust measurements are conducted according to VDI 2066

at a straw pellets combustion furnace with a condensing heat exchanger. The mean dust emission

was 75-100 mg/Nm³. The particle size distribution was determined by ELPI-measurements. By

increasing the packing density of the quartz wool from 0.06 g/cm³ (according to VDI 2066) to

0.15 g/cm³ the retention potential was enhanced significantly. Condensing flue gas, on the other hand,

reduces the retention potential to only 92.4%. Furthermore a statistical spread of the retention

potential could be observed. Therefore the utilization of a secondary filter downstream is

recommended also for particulate matter emission higher than 50 mg/Nm³.

Leipzig, 15.11.2010

The retention potential of stuffedfiltering cartridges from dustmeasurement in condensing flue gas

DI Manuel Schwabl

Ort, DatumFolie 2

Overview

■ Methods and Materials

■ Influence on retention potential

■ Mass loss of quartz fibre material

■ Packing density

■ Condensing flue gas

■ Conclusions

Ort, DatumFolie 3

Mesurement method

■ Measurement of particulateemission according to VDI 2066

■ Measurement setup– a. secondary filter, quartz

fibre– b. stuffed filtering

cartridge– c. measurement rack

■ Filters are Conditioned at 130°C for 10h

■ Stuffing material is quartzfibre mean diameter of 10µm

■ Isokinetic probe sampling■ Trace heating of

measurement rack to 130°C

Ort, DatumFolie 4

Combustion system

■ Straw pellets combustion (12kW) with condensing heat exchanger.

■ Dust emission: 75 mg/MJ (full load), 88 mg/MJ (minimum load)

ELPI Measurements

Ort, DatumFolie 5

Influence on retention potential

■ Systemic gain of mass on secondary filter dueto loss of quartz fibre from the stuffed cartridgefilter

■ Separation efficiency of stuffed cartridge filter

■ depending on packing density

■ Depending on parameters of particleemission

– Particle size distribution

■ Flue gas condition

Retention potential

Ort, DatumFolie 6

Loss of quartz fibre

Testing method:

■ Varying the stuffing method

■ Dry stuffing

■ Wet stuffing

■ With or without suction cleaning (5min withwater-jet vacuum pump)

■ Tests in filter rack with ambient air

■ 30l/min for 10mins

■ Measurement of loss of filter cartridge and massgain on secondary filter

Ort, DatumFolie 7

Loss of quartz fibre

Results:

■ No significant difference forthe surveyed stuffing methods

■ Mean loss of filtering material 0,65mg

■ Only 10% recover of thefiltering material on thesecondary filter

■ Loss due to transportation 0,25 mg

■ Loss due to handling intothe measurement rack

■ Minimal adhesion of quartz fibre on secondaryfilter

Ort, DatumFolie 8

Packing density

Test setup

■ Varying packing density

■ Determination of retention potential by dustmeasurements at thecombustion system (fullload)

Results

■ Increasing retentionpotential for higherpacking density VDI 2066

Ort, DatumFolie 9

Condensing flue gas

■ 21 single measurements for each operation condition■ Volume flow 25-30l/min

■ Decline of retention potential of measurements during condensing conditions.■ From 98.7 to 92.4 during full load■ From 99.1 to 97.2 during minimum load

■ Minor impact on measurements during minimum load conditions

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ad

Ort, DatumFolie 10

Condensing flue gas

■ Separation of particles > 1µm shifts the particle size distributionduring condensing conditions. �Decline of retention potential

■ Total separation efficiency of condensing heat exchanger10-25%

■ Condensate influences theretention potential

■ By increasing flue gas velocitythe amount of liquid waterphase is rising.

■ Impacting Condensate on thefilter cartridge reduces theretention potential.

Ort, DatumFolie 11

Conclusion

■ Loss of quartz fibre is independet of the stuffing method

■ Increase of the packing density increases the retention potential of stuffed filtering cartridges

■ Retention potential > 98% is achieveable

■ Secondary filter is recommended also for higher particulateemission, if facing a condensed flue gas.

Thank youfor your attention

DI Manuel SchwablJunior Researcher

T + 43 (0) 7416 52238-41F + 43 (0) 7416 52238-99M + 43 (0) 650 6000 625manuel.schwabl@bioenergy2020.eu

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