institute of chemical engineering page 1 achema 2012 mechanical process engineering dipl.-ing. dr....
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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
Institute of Chemical Engineering page 2Achema 2012
Mechanical Process Engineering
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
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Mechanical Process Engineering
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
Characterization and separation of metal working fluid mist
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Mechanical Process Engineering
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 and separation of metal working fluid mist
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Mechanical Process Engineering
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”
Characterization and separation of metal working fluid mist
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Mechanical Process Engineering
Filter test rig
Aerosol-generator
Data acquisition
Filter holder and suck off pipe
Aerosol measurement
Characterization and separation of metal working fluid mist
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Mechanical Process Engineering
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
Characterization and separation of metal working fluid mist
Institute of Chemical Engineering page 8Achema 2012
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
Institute of Chemical Engineering page 9Achema 2012
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)
Institute of Chemical Engineering page 10Achema 2012
Mechanical Process Engineering
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 …
Characterization and separation of metal working fluid mist
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Mechanical Process Engineering
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
Characterization and separation of metal working fluid mist
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Mechanical Process Engineering
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
Characterization and separation of metal working fluid mist
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Mechanical Process Engineering
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
Characterization and separation of metal working fluid mist
Institute of Chemical Engineering page 14Achema 2012
Mechanical Process Engineering
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
Characterization and separation of metal working fluid mist
Institute of Chemical Engineering page 15Achema 2012
Mechanical Process Engineering
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.
Characterization and separation of metal working fluid mist