Institute of Chemical Engineering page 1 Achema 2012 Mechanical Process Engineering Dipl.-Ing. Dr. Thomas Laminger Univ. Prof. Dr. Wilhelm Höflinger Contact:

Institute of Chemical Engineering page 1Achema 2012

Mechanical Process Engineering

Dipl.-Ing. Dr. Thomas Laminger

Univ. Prof. Dr. Wilhelm Höflinger

Contact: [email protected]

Characterization and Separation of

Metal Working Fluid Mist



During machining fine droplets and vapor of metalworking fluids (MWF) are generated by the rotating tool or grinding wheel which can cause occupational health problems.

MWF are complex mixtures that could contain petroleum products, animal and vegetable fats and variety of additives to improve their properties. They are utilized either as pure oils or as emulsions of oil in water (range 1-10 %).

Background

Characterization and separation of metal working fluid mist



Workers are usually exposed to MWFs by inhalation and through skin contact, which can cause a variety of health problems: dermatitis, respiratory problems and long –term exposure can lead to several cancer types.

For this reason it is very important to determine appropriate ventilation system:

• full enclosed housings

• half enclosed housings

with appropriate filter elements to reduce working area’s air contamination

Background

Without any enclosures

Full enclosed housing




The range of installed filter medias, used oil/emulsions and working processes is very wide. But still there are no standards to test and certificate these MWF mist filters filter medias.

Development of standard characterization method of MWF mist filters

Introduction and purpose of the study




Characterization of metal working fluid mist filtersusing a filter test rig

To characterize and compare different filter media a filter test rig was build up. Measured parameters are e.g. pressure drop, separation efficiency and drainage flow.

flow velocity

Dp

blower

MWF pump

Filter holder with test elements

Aerosol generator

Metalworking fluid mist

Drainage flow

Aerosol measurement

“CYCL-FID”




Filter test rig

Aerosol-generator

Data acquisition

Filter holder and suck off pipe

Aerosol measurement




Aerosol measurement device “CYCL-FID”

For an on-line detection of MWF-mist emissions a new measurement method was established. To detect vapour and droplet phase a combination of a classifier, evaporator and flame-ionization-detector was built up. A cyclone as classifier allows a continuous change of the Cut-Off-diameter by changing the air flow by the cyclone.

“CYCL-FID-Measurement”

Ingoing air flow

PM1 Cyclone

FID PCS Flow Valve for air flow control

Suck off pipe

Optional PCS for calibration

Sampling and measurement

Sampling



Mechanical Process EngineeringCharacterization and separation of

metal working fluid mist

CYCL-FID-Measurement Using different Cut-Off-Sizes the MWF-Emission is sequential classified and

detected after evaporation with the FID. For example a MWF-Emission is classified using 3 different Cut-Off-Sizes:

FID 1,0

FID 2,5

FID All

FID 0,5

Cut-Off 1,0µm

Cut-Off 2,5µm

No Cut-Off

MWF-Emission0,5 – 1,0 µm 1,0 – 2,5 µm >2,5 µmVapor+

0-0,5µm

Cut-Off 0,5µm

4 FID-Signals:

Vapor +0-0,5µm

Vapor +0-2,5µm

Vapor +0-1,0µm

Vapor +0- >2,5µm

Vapor and Droplets


Mechanical Process EngineeringCharacterization and separation of

metal working fluid mist

CYCL-FID-Measurement By subtracting two classified FID-Signals a Droplet-Size-Distribution can be

calculated. Vapor is per definition part of the smallest used Cut-Off-Size

Cut-Off [µm]

FID

Sig

nal

(ppm

pro

pane

-equ

ival

ent)

FID 1,0

FID 2,5

FID 5,0

FID 0,5

0,5 1,0 2,5 Aerodynamic diameter [µm]

FID 0

,5

FID 1

,0 –

FID

0,5

FID 2

,5 –

FID

1,0

FID 5

,0–

FID 2

,5

FID ALL

5,0

FID A

LL– FID

5,0

Vapor + droplets <0,5µm

0,5 1,0 2,5 5,0

FID

Sig

nal

(ppm

pro

pane

-equ

ival

ent)



Filter-class

Minimal requested separation efficiency (%) in the steady state condition

<0.3µm(including

vapor)0.3-1µm 1-3µm 3-10µm

1 - - 0≤E3<35 0≤E4<50

2 - - 35≤E3<45 50≤E4<60

3 - 0≤E2<35 45≤E3<55 60≤E4<70

4 - 35≤E2<45 55≤E3<65 70≤E4<80

5 - 45≤E2<55 65≤E3<75 80≤E4<85

6 - 55≤E2<65 75≤E3<85 85≤E4<90

7 0≤E1<5 65≤E2<75 85≤E3<90 90≤E4<95

8 5≤E1<10 75≤E2<85 90≤E3<95 95≤E4

9 10≤E1<20 85≤E2<95 95≤E3 95≤E4

10 20≤E1 95≤E2 95≤E3 95≤E4

PROPOSAL OF A CLASSIFICATION SYSTEM FOR METAL WORKING FLUID MIST SEPARATORS

Filter-classes:1-3: Pre-Separators, Coarse wire mesh …4-6: Coarse glass-fiber filter, wire/glass-fibre filters …7-10: Fine glass-fiber filters, HEPA filters …

Further report values:Airflow rate, Test substance, stationary pressure drop, total holdup, oil holdup …




0 100 200 300 400 500 6000

200

400

600

800

1000

1200

Time [min]

Pres

sure

dro

p [P

a]Filter medium: Wire/glass-fiber filterTest substance 10% Emulsion, mineral oilFilter face velocity: 5000m³/(m²/h)

0 100 200 300 400 500 6000

200

400

600

800

1000

1200

Time [min]

Pres

sure

dro

p [P

a]Filter medium: Wire/glass-fiber filterTest substance 10% Emulsion, mineral oilFilter face velocity: 5000m³/(m²/h)Filter loading: 0.05 and 0.5g/(cm²/min)

B

A

ACCELERATED FILTER AGEING TEST PROCEDURE

The same stationary pressure drop is achieved with (A) accelerated

and (B) non accelerated filter ageing procedure.

1) „Accelerated Ageing“transfer the filter in a stationary condition using the ageing nozzle and the aerosol generator

2) „Stabilizing“shut down of the ageing nozzle – using only the aerosol generator

3) „Measuring“measuring the stationary raw and clean gas concentration with the CYCL-FID-measurement device(only the aerosol generator)

• Ageing nozzle: shortens the ageing time• Aerosol generator: generates the test aerosol

3-step test procedure




DEMONSTRATIVE MEASUREMENT EXAMPLE

Test filter

Fine wire/glass-fiber filter, 200x200x40mm

Test parameters

Filter face velocity: 5000m³/(m²h)

Test substance: 10% emulsion, mineral oil

Filter loading (with ageing nozzle): 0.5g/(cm²/min)

Test aerosol concentration: 56mg/m³

0.10 1.00 10.000

1

2

3

4

5

6

0

10

20

30

40

50

60

Particle size[µm]

dCm

[mg/

m³]

Sum

(dCm

) [m

g/m

³]

Test aerosol: Particle size distribution (PCS 2010, Palas ®)

Aerosol generator: 7500rpm; 1.2L/min emulsion flow




0 20 40 60 80 100 120 140 160 180 2000

100

200

300

400Oil holdup

Total holdup

Time [min]

Hold

up [g

]

0 20 40 60 80 100 120 140 160 180 2006

8

10

12

14

16

Raw gas emulsion

Drainage emulsionO

il co

ncen

trati

on [%

]

0 20 40 60 80 100 120 140 160 180 2000

200

400

600

800

1000

1200

1400

Pressure drop

Drainage

Drai

nage

[g/m

in],

Pres

sure

dro

p [P

a]TIME DEVELOPMENT AND STATIONARY VALUES OF THE PRESSURE DROP,TOTAL HOLDUP AND OIL HOLDUP

StabilizingAccelerated Ageing Measuring

Pressure

drop

Total

holdup

Oil holdup




STATIONARY RAW GAS AND CLEN GAS CONCENTRATION AND THE FRACTIONAL SEPARATION EFFICIENCY IN FOUR FRACTIONS

<0.3µm 0.3-1µm 1-3µm 3-10µm0.0

0.4

0.8

1.2

1.6

2.0

0%

20%

40%

60%

80%

100%

Raw gasClean gasFractional separation efficiency

Particle size range

FID

con

cent

rati

on [p

pm]

Fractional separati

on efficiency [%

]

Filter medium: Fine wire/glass-fiber filterFilter face velocity: 5000m³/(m²h)Test substance: 10% Emulsion, mineral oilTest aerosol concentration: 56mg/m³

Fractional separation efficiency:<0.3µm: 0.240.3-1µm: 0.651-3µm: 0.983-10µm: 0,98

Filter medium: Fine wire/glass-fiber filterFilter face velocity: 5000m³/(m²h)Test substance: 10% Emulsion, mineral oilTest aerosol concentration: 56mg/m³

Stationary fractional separation efficiency:<0.3µm: 0.240.3-1µm: 0.651-3µm: 0.983-10µm: 0.98

Filter-class

Minimal requested separation efficiency (%)

<0.3µm 0.3-1µm 1-3µm 3-10µm

1 - - 0≤E3<35 0≤E4<50

2 - - 35≤E3<45 50≤E4<60

3 - 0≤E2<35 45≤E3<55 60≤E4<70

4 - 35≤E2<45 55≤E3<65 70≤E4<80

5 - 45≤E2<55 65≤E3<75 80≤E4<85

6 - 55≤E2<65 75≤E3<85 85≤E4<90

7 0≤E1<5 65≤E2<75 85≤E3<90 90≤E4<95

8 5≤E1<10 75≤E2<85 90≤E3<95 95≤E4

9 10≤E1<20 85≤E2<95 95≤E3 95≤E4

10 20≤E1 95≤E2 95≤E3 95≤E4

Filter reach Filter-class 7




SUMMARY

In analogy to existing norms and standards for dust filters a standardized test procedure for metal working fluid mist filters was developed:

- A filter test rig with its main components was presented. The CYCL-FID-measurement device and the principle to measure the droplet and vapor concentration of a mist emission in several particle size fractions was shown.

- A three-step filter test procedure (accelerated filter ageing) was described using an ageing nozzle which allows the determination of the stationary filtration specific parameters which are pressure drop, total holdup, oil holdup and the fractional separation efficiency in a relative short test time.

- A classification system with 10 filter-classes for MWF mist filters was proposed. The system includes four particle size ranges (<0,3µm/0.3-1µm/1-3µm/3-10µm) with minimal requested separation efficiencies. The particle size range “<0.3µm” includes also the vapor fraction of the mist emission.

With the filter test rig, the developed accelerated filter ageing procedure and the classification system it is now possible to evaluate and compare different mist separators in a very short time.


Documents

Institute of Chemical Engineering page 1 Achema 2012 Mechanical Process Engineering Dipl.-Ing. Dr. Thomas Laminger Univ. Prof. Dr. Wilhelm Höflinger Contact: