DEVELOPMENT OF A RECYCLING SYSTEM FOR METALWORKING FLUIDS

Wong Kien Kuok

Doctor of Philosophy 2012

lUll KlUdnllll MakJumat Akadebll . UNIVERSm MALAYSIA SAKAWA"

DEVELOPMENT OF A RECYCLING SYSTEM FOR METALWORKING FLUIDS

.1'.

WONG KIEN KUOK

A thesis submitted

in fulfillment of the requirements for the degree of

Doctor ofPhilosopfiy In Civil Engineering

Faculty of Engineering

UNIVERSITI MALAYSIA SARA W AK

2012

,....

Specially dedicated to

my beloved wife, Lock Hei and

my wonderful children, Zhong Rui and Zhong Yan

Acknowledgements

First of all, I would like to thank God for giving me wisdom, strength and perseverance to

complete this dissertation. My gratitude is also extended to other individuals, bodies,

organizations and institutions for their kind and generous assistance throughout the entire

research period.

I would like to convey my sincere appreciation to my Supervisor, Professor Ir. Dr Law Puong

Ling, and Co-Supervisors, Professor Ng Chee Khoon, Associate Professor Dr Ha How Ung

and Associate Professor Dr Azhaili Baharun for their unceasing guidance and support.

thank them also for their patience, kindness, constructive ideas and advice, to steer me

towards the research direction.

Many thanks go to the Director of ELITE Industries Sdn. Bhd., Mr Wong Hai Tien for his

willingness and generosity in providing the necessary assistance. My heartfelt appreciations

also go to the technicians and administrative staff of the Faculty of Engineering, Universiti

Malaysia Sarawak (UNIMAS) for their help and involvement. Special thanks are directed to

Graduate Studies and Research Support Division and Ministry of Science, Technology and

Innovation (MOSTI) for the financial support through IRPA Grant.

I would like to acknowledge the authors of all journal papers, theses, project reports and other

references for their kindness in sharing their works. Last but not least, my greatest thanks and

appreciation to my beloved wife, children, family and friends for their moral support, prayer

and advice that had sustained me throughout my doctoral studies.

I

Abstract

(Over 2 billion litres straight-oil and water-based metalworking fluids (MWFs) are consumed

currently worldwide, portraying a great demand for this non-renewable feedstock. It is a great

challenge for the manufacturers, suppliers and end users to develop efficient and effective

MWF treatment systems to tackle health and safety issues, as well as preserving the

environment. In such the importance of developing a MWF Recycling System (MRS) which

primarily consists of 4 operational units; an upflow filtration, enhanced gravity separator,

aeration-filtration unit and pasteurization process, are outlined in this thesis The upflow

filtration and aeration filtration consists of 5 layers of geotextile with 120 llm pore size for

removal of metal chips and oxidized metal chips. The enhanced gravity separator is a circular

separator with 4 series of inverted and upright alternating coalescing frustums to enhance

gravity separation of metal chips and coalescence of tramp oils. The individual unit processes

and treatment performances were evaluated with respect to removal efficiencies of oil and

solid particles, status of lubricity as a function of application and microbial contaminant

growth Qver time. Experimental results were compared with the existing Computer

Numerical Control (CNC) built-in MWF Treatment System. At design flowrate of 1.0x10-5

m3/s, the upflow filtration unit and enhanced gravity separator were observed to achieve

particle size removal of ~6.7111m and ~3.28 llm, respectively. The enhanced gravity

separator removed approximately 97.25% of tramp oil at 1.0x10-5 m3/s flowrate. This MRS

also had experimentally demonstrated to remove significant amount of silt and clay in the

MWF, whereby silt and clay particles in the MWF were mainly due to reuse and recycling of

MWF. A comparison of MRS with CNC MWF Treatment System with respect to tramp oils

and solid particles removal efficiencies reviewed that MRS was able to treat the used coolant

11

I

to an acceptable quality range, whereby CNC Coolant Treatment System was incapable of

effectively treating the MWF. The lubricity tests of spent coolant through recycling process

by MRS produced acceptable quality recycled coolant within workable range over a longer

period as the friction coefficient (Ps) maintained in the range of 0.1683 to 0.1788, whereby the

CNC built-in coolant filtration system showed a rapid drop in lubricity during the fourth and

fifth weeks with ps in the range of 0.1929 to 0.1956, and must be disposed off within 4 to 8

weeks times. Microbial contaminant growth in MRS recycled (treated) coolant was

approximately 9 times lower than that of CNC filtered recycled coolant. Economic analysis

on MRS and CNC filtration system showed that relatively higher initial investment cost of

MRS can be offset by its low operation and maintenance costs, whereby the breakthrough

period is about 2 years.

iii

Abstrak

Pergembangan Sistem Merawat Logam Bekerja Cairan

Lebih daripada 2 bilion liter logam bekerja cairan (MWF) telah digunakan dan disalurkan ke

alam semulajadi secara global. Pemprosesan dan kitar semula MWF yang terpakai menjadi

satu cabaran kepada pengeluar, pembekal and pengguna MWF. Dengan itu, pengembangan

dan kerja untuk mengenalpasti prestasi suatu Sistem Kitar Semula Logam Bekerja Cairan

(MRS) yang terdiri daripada 4 unit operasi iaitu penyaringan aliran keatas, unit pemisahan

gravity dipertingkat, aerasi-penyaringan dan pasteurisasi, telah dikaji di tesis ini. Tangki

penyaringan aliran keatas dan aerasi-penyaringan menggunakan geotekstil dengan liang

pembukaan 120 fUrl sebagai medium pemisahan untuk memisah partikel logam atau partikel

logam yang teroksida. Unit pemisah graviti dipertingkat adalah tangki bulat yang terdiri

daripada beberapa 4 siri frustum pergabungan condong yang tegak dan terbalik untuk

mendorong proses pemisahan graviti dan pergabungan titisan-titisan minyak terderap dan

partikel logam. Setiap unit proses perawatan dan keseluruhan sistem kitar semula dinilai

untukpemisahan minyak dan keseluruhan pepejal ampaian (TSS), dan kemampuan mengawal

elumasi dan pertumbuhan mikrob. Hasil eksperimen dibandingkan dengan sistem perawatan

MWF yang terbina dalam kawalan berangka computer (CNC) yang digunakan di industri.

Pada kadar aliran rekaan 1.0 x ](J5 m3/s, tangki penyaringan aliran ke atas dan unit

pemisahan graviti dipertingkat dapat mencapai pemishaan partikel dengan saiznya ~ 6.71J.lm

and c 3.28 J.lm masing-masing. Tangki pemisahan graviti dipertingkat dapat mencapai

pemisahan minyak terderap sebanyak 97.25% pada kadar aliran rekaan 1.0 x 10-5 m3/s.

Sistem rawatan dapat memisah kontaminan (minyak terderap dan lumpur / tanah liat) yang

-

IV

,......

ditambah dalam MWF dan penurunan keseluruhan kandungan minyak dan TSS dalam MWF

disebabkan oleh pengunaan berulang MWF. Perbandingan sistem rawatan CNC dengan

sistem rawatan yang dicadang menunjukkan sistem rawatan yang dicadang berkebolehan

merawat MWF terpakai ke tahap kualiti yang boleh diterima. Manakala sistem rawatan CNC

tidak mampu merawat MWF secara berkesan. Eksperimen kemampuan melumas terhadap

MWF terpakai yang dirawat menggunakan MRS yang dicadang menunujukkan MWF

diproses berkualiti dan berkebolehkerjaan untuk jangka masa yang lebih panjang

memandangkan pekali geserannya (Ils) berada di antara 0.1683 and 0.1788. Namun sistem

rawatan CNC menampilkan kemerosotan kemampuan melumas yand mendadak pada minggu

keempat atau kelima, terpaksa dibuang dengan f.ls berada di antara 0.1929 and 0.1956.

Mikrob kontaminan sistem rawatan yang dicadang adalah 9 kali lebih rendah berbandingkan

dengan sistem CNC akibat pemecatan dan pengawasan contaminant yang efektif dalam

MWF Dalam analisis ekonomi, walaupun kos pendahuluan MRS lebih tinggi, tetapi

dikompromikan dengan kos operasi dan penyelengaraan setahun yang lebih rendah jika

berbanding dengan sistem jiltrasi mesin CNC dan ini membolehkannya menjadi lebih

ekonomi dalam masa 2 tahun.

v

Pusat Kbidmllt Maklumat AkademiJ< lfNlVERSm MALAYSIA SARAWAK

Table of Contents

Acknowledgements

Abstract

Abstrak

Table of Contents

List ofTables

List of Figures

List ofNotations

List ofAbbreviations

CHAPTER 1 INTRODUCTION

1.1 Introduction

1.2 Current Situation and Problem Statement

1.3 Objectives and Specific Aims

1.4 Scope of Work

1.5 System Description

1.6 Theoretical Principles of Inclined Parallel Coalescence

Plates for Enhancement of Oil-Coolant-Solids

Separation

1.7 Significance of the Study

1.8 Thesis Outline

CHAPTER 2 LITERATURE REVIEW

2.1 Metalworking Fluids

2.1.1 Mobilcut 102

PAGE

11

IV

VI

xi

xiv

xx

XXIV

1

1

4

4

6

10

14

17

18

18

20

vi

I

2.2 Contaminants of used Metalworking Fluids 22

2.3 Metalworking Fluids Management 24

2.3.1 Tramp Oil Removal 26

2.3.2 Metal Chips and SwarfRemoval 31

2.3.3 Management of Microbial Contaminant 38

2.3.4 Gravity Separation 39

2.3.5 Boycott Effect 42

2.3.6 Types of Gravity Separators for Oil Removal 44

2.3.6.1 American Petroleum Institute (API)

Separators 44

2.3.6.2 Coalescing Plate Separators 46

2.3.6.3 Coalescing Tube Separators 49

2.3.6.4 Packing Type Separators 50

2.3.7 Types of Gravity Clarifier for Suspended Solids

Removal 50

2.3.7.1 Sedimentation Tank 51

2.3.7.2 Inclined Plates and Tube Settlers 51

2.4 Ring Lubricity Test 53

2.5 Previous Researches 56

2.5.1 MWFs system 56

2.5.2 Biological Treatment of spent MWFs 57

2.5.3 Filtration ofMWF 58

2.5.4 Enhanced gravity separator 59

2.5.5 Upflow filtration 65

2.6 Summary on Review of Past Researches 66

CHAPTER 3 MATERIALS AND METHODS 67

Vll

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3.1 System Description 67

3.1.1 MRS Features and Design Consideration 68

3.1.2 Operation of MRS (Oil-Coolant-Solids

Separation) 69

3.2 Design and Process 71

3.2.1 Design of Coalescing Plate Separator 71

3.2.1.1 Use of Coalescence Plates to

Enhance Removal of Oil Droplets

and Metal Chips from Machining

Coolant 72

3.2.1.2 'Inlet Perforated-Pipe Distributor 74

3.2.1.3 Inlet Distributor Design 78

3.2.1.4 Theoretical Design Principles of

Coalescing Plate Separator 79

3.2.1.5 Separation Basin Design 83

3.2.1.6 Coalescing plate separator Sizing,

Outlet Baffle and Overflow Weir 85

3.2.1.7 Coalescing Frustums Design 88

3.2.2 Filtration and Aeration Units 92

3.2.2.1 Geotexti1es 95

3.2.3 Pasteurization Tank Design 96

3.2.4 Test Rig Design 100

3.3 Materials 105

3.3.1 Preparation of Mobilcut 102 105

3.3.2 Mixing Tank Set-Up and Sample Preparation 105

3.4 Instrumentation 109

viii

,... I

CHAPTER 4

3.4.1 Oil Concentrations 1D9

3.4.2 Suspended Solids 110

3.4.3 Lubricities 110

3.4.3.1 Spring Stiffness 111

3.4.3.2 Experimental Setup of Ring

Lubricity Test 113

3.4.4 Total Bacteria Counts 115

3.5 Experimental Procedures 115

RESULTS AND DISCUSSION 123

4.1 Unit Process Performances 123

4.1.1 Removal efficiency ofTSS by MRS Filtration

and Aeration-Filtration Units 123

4.1.2 Removal efficiency ofTSS by MRS coalescing

plate separator 125

4.1.3 Enhanced Coalescing Plate Separator - Oil

Removal Efficiencies 131

4.2 Quality of Recycled Spent Coolant of ELITE CNC

Filtration System 138

4.3 Performance of MRS Coolant Recycling System 142

4.3.1 Control Experiment - Initial Concentration of

Oil, TSS and Lubricity of Fresh Coolant for

Different Coolant-Water Dilution Ratios 142

4.3.2 Control Experiment- Lubricity of Fresh Coolant

at Dilution Ratio 1: 1 00 for Different TSS

Concentrations 143

4.3.3 MRS Coolant Recycling System - Virgin

Coolant Recycling 144

IX

4.3.4 MRS Recycled Spent Coolant - Coolant

Concentration Adjusted Once 147

4.3.5 MRS Recycled Spent Coolant - with

Concentration Adjusted Every Run 150

4.4 Economic Analysis 154

CHAPTERS CONCLUSIONS AND RECOMMENDATIONS 158

5.1 Conclusions 158

5.2 Recommendations for Future Work 159

REFERENCES 161

APPENDICES 166

Appendix A: Patent Contents and Specification (Intellectual

Property Filed in Malaysia) 166

Appendix B: Certificates and Awards 176

Appendix C: Experimental and Technical Data 179

Appendix D: Inlet Perforated-Pipe Distributor Design 190

x

List of Tables

Table Description Page

Table 2.1: Properties of Mobilcut 102 ................................. ................................................ 22

Table 2.2: Organisms found in metalworking fluids (Bennett, 1989)

1st 4th fro . d· ·fi· 90

................................. 23

Table 2.3: Equipment and techniques used for control and removal of4

common contaminants (MnTAP, 2004) ................. ............................................ 27

Table 3.1: Typical separator design requirements and criteria (Corbitt, 1989) ................. .. 72

Table 3.2: Inlet distributor design calculations at various flowrates ................................... 81

Table 3.3: Plan area, Ap required versus various flowrates, Q............................................. 85

Table 3.4: Retention times, t versus various flowrates, Q................................................... 87

Table 3.5: to sturn senes eSlgn speCI catIOns..................................................... .

Table 3.6: Summary of coalescing plate separator design details and parameters .............. 91

Table 3.7: Influent suspended solids preparation: water-to-siltlclay ratio

Table 3.8: Influent TSS concentrations, Css, retention time, t and influent

......................... 116

flowrates, Q....................................................................................................... 117

Table 3.9: Influent oil concentrations, Ciss , retention time, t and influent

flowrates, Q....................................................................................................... 117

Table 3.10: Test sample preparation: water-hydraulic oil ratio ........................ ................... 118

Table 3.11 : Experimental procedures ............................................................ ...................... 122

Table 4.1: Correlationship of coalescing plate separator effluent TSS

concentration, Cesss and influent TSS concentration, Ciss versus

flowrate, Q........................................................................................................ 127

Table 4.2: Correlationship of coalescing plate separator TSS removal

efficiency, Esss and influent TSS concentration, Css versus flowrate,

Q........................................................................................................................ 129

Xl

Table 4.3: Coalescing plate separator TSS removal efficiency, Esss at different

influent TSS concentrations, Css and flowrates, Q; Average TSS

removal efficiency and removable particle size at different flowrates,

Q.................................. .. ......... .......... ................................................................. 130

Table 4.4: Correlationship of coalescing plate separator effluent oil

concentration, Ceos and influent oil concentrations, Cia versus

Table 4.5: Correlationship of separator tank oil removal efficiency, Eos and

Table 4.6: Capital and operation/maintenance costs of MRS & CNC filtration

Table CI0: Effluent oil concentration, TSS level and lubricity of recycled MWF

after filtration, separation and aeration processes at dilution ratio

flowrates, Q .......... .. ..... .................... .......... ....................................... .......... ....... 135

influent oil concentration, Co for various flowrates, Q ......................... ........... 138

system .................................................................. ............................................. 155

Table 4.7: Cash flow - CNC filtration system and MRS ................................................... 157

Table 4.8: Accumulated cash flow - CNC filtration system and MRS ............... .................. 157

Table C 1: Initial Lengths, Lo of the three springs .............................................................. 179

Table C2: Load and corresponding elongation for Spring 1 ...... .. ..................................... 179

Table C3: Load and corresponding elongation for Spring 2 ..................................... ........ 179

Table C4: Load and corresponding elongation for Spring 3 ............................................. 180

Table C5: TSS removal efficiency of filtration tank ............................ .. ........................... 180

Table C6: TSS removal efficiency of coalescing plate separator ..................................... 181

Table C7: Coalescing plate separator influent oil concentration, Cio, effluent oil

concentration, Ceos, oil removal efficiency, Eos at different flowrates,

Q......... ............................................................................................................... 182

Table C8: Initial oil concentration, TSS level and friction coefficient.. ............................ 183

Table C9: Correlationship ofTSS concentration and friction coefficient.. ....................... 183

1:100 (MRS) ..................................................................................................... 184

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Table C11: Effluent oil concentration, TSS level, lubricity and bacteria counts

for spent MWF after filtration, separation and aeration processes

with single concentration adjustment ........ .. .......................... .......... .......... ....... 185

Table C1 2: Effluent oil concentration, TSS level, lubricity and bacteria counts

for spent MWF after filtration, separation and aeration processes

(concentration adjusted for every run) .................................. .. .......................... 186

Table Cl3: Effluent oil concentration, TSS level, lubricity and bacteria counts of

ELITE CNC samples ........................................................................................ 187

Table C14: Polyfelt TS 20 Geotextiles - Technical Data .................................................... 188

Xlll

List of Figures

Figure Description Page

Figure 1.1: The 4-Stage Recycling System for MWFs ........................................................... 6

Figure 1.2: Enhanced circular gravity coalescence separator with series of

conical parallel coalescence frustums alternately arranged in upright

and inverted positions ........................... .... ............................................................ 8

Figure 1.3: Forces acting on oil droplets while sliding along coalescing plates, in

which Fs = buoyancy force and Fb= drag force .................................................. 10

Figure 1.4: Mechanism ofOil-Coolant-Solids removal by Inclined Parallel

Coalescing Plates ................................................................................................ 13

Figure 2.1: (a) Mobilcut 102 in 20L bucket, (b) Mobi1cut 102 in amber clear

color and (c) Milky emulsion of Mobi1cut 102 when mixed with

water.................................................................................................................... 20

Figure 2.2: Schematic diagram of Centrifuge typically used for tramp oil

removal (Bray, 2001) .............................................................................. .... ........ 3 1

Figure 2.3: Typical flow through a hydro cyclone (lAMS and WRATT, 2005) ................... 34

Figure 2.4: Schematic diagram of centrifuge used for particle separation (Bray,

2001) ............................ ... .................................................................................... 35

Figure 2.5: Comparison ofparticle settling characteristics in a vertical tube and

an inclined tube (RPI, 1996) ............................................................................... 43

Figure 2.6: Typical API separator (Wikipedia, 2009) ........ ................................................... 45

Figure 2.7: Inclined plate rectangular separator (Mohr, 1992) ................. ............................ 47

Figure 2.8: Flat corrugated plates (Mohr, 1992) ................................................................... 48

Figure 2.9: Typical multiple angle coalescing pack (Mohr, 1992) ....................................... 49

Figure 2.10: Packing type separator (Mohr, 1992) ................................................................. 50

XIV

Figure 2.11: Zones of sedimentation: (a) horizontal flow clarifier; (b) up flow

clarifier (Tchobanoglous et al., 2003)................................... .............................. 51

Figure 2.12: Inclined-plate module in (a) rectangular separator and (b) circular

separator (Reynolds, 1982) ...... ... ...................... ................................... .. ...... .. ..... 52

Figure 2.13: Module of inclined tube and its operation (Reynolds, 1982;

Tchobanoglous et aI., 2003) ............................................................................... 53

Figure 2.14: Wire passing over a circular drum (Riley et al., 2002)............... ........................ 54

Figure 2.15: Free body diagram of a small segment of the wire (Riley et aI., 2002).............. 54

Figure 3.1: Coalescing Plate Separator - Dimensional Details ............................................. 70

Figure 3.2: Perry and Green design module horizontal perforated-pipe

distributor (Perry and Green, 1997) .................................................................... 75

Figure 3.3: Ideal circular settling basin, with flowrate (Q), radius (r), depth (h)

and settling velocity of the solid particle or rising velocity of the oil

Figure 3.4: (a) Outlet periphery v-notch overflow weir channel, and (b) Outlet

droplet (v) (Reynolds, 1982) .................... .......................................................... 80

launder design parameters .................................................................................. 87

Figure 3.5: Coalescence frustum design details and parameters ........................................... 89

Figure 3.6: Upflow filtration and aeration units - side elevation and plan ............................ 93

Figure 3.7: Filtration and aeration units - front and rear elevations ...................................... 94

Figure 3.8: Plots of bacteria growth rates versus Time ......................................................... 97

Figure 3.9: Specification details of pasteurization unit.. ....................................................... 99

Figure 3.10: Specifications of test rig for mounting the filtration tank, coalescing

plate separator, aeration-filtration tank and pasteurization unit

(isometric view) ........................................................................................ ... ..... 101

Figure 3.11 : Side elevation of test rig mounted with complete MRS

Figure 3.12: Plan view and Section A-A of the test rig mounted with complete

................................... 102

MRS .................................................................................................................. 103

xv

Figure 3.13: Front view of the test rig mounted with complete MRS ...... .... ......................... 104

Figure 3.14: Experimental setup of MRS: (a) Schematic Process flow, and (b)

Pilot Scale ......................................................................................................... 106

Figure 3.15: Particle size distribution of sieved silt and clay samples (Geospec,

2007) ................................................................................................................. 107

Figure 3.16: Sample collection points; (a) Sample collected from effluent of

mixing tank, (b) Sample collected from effluent of filtration unit, ( c)

Sample collected from effluent of mixing tank and (d) Sample

collected from effluent of coalescing plate separator ....................................... 108

Figure 3.17: Horiba model OCMA-31 0 oil water analyzer and S316 Solvent ..................... 109

Figure 3.18: Spectrophotometer HACH DRl2400 ........................................... .. ............ .. ..... 110

Figure 3.19: Setup in laboratory to determine spring stiffness, k .......................................... 111

Figure 3.20: Applied loads and corresponding elongation of 3 springs ................................ 113

Figure 321: Ring lubricity test in laboratory ..................................... ... ........................ ... ..... 114

Figure 3.22: Schematic diagram for lubricity test and its free body diagram .......... .. ........... 114

Figure 4.1: Up flow filtration unit - TSS removal efficiencies, EssjvS time at

flowrates 1.0x10-5 and 0.5xlO-5 m3/s ............................. .. ................................. 124

Figure 4.2: Extrapolation ofminimum removable particle size of upflow filter

medium that consists of 5 layers of TS20 geotextile ..... ................................... 124

Figure 4.3 : Coalescing plate separator effluent TSS concentrations, Cesss at

different influent TSS concentrations, Ciss and flowrates, Q ... .............. .... ....... 125

Figure 4.4: Plots of power relationship of coalescing plate separator effluent

TSS concentrations, Cesss and influent TSS concentrations, Ciss for

various flowrates, Q............ ............... ............................................................... 126

Figure 4.5: Coalescing plate separator TSS removal efficiencies, Esss at different

influent TSS concentrations, C;ss and flowrates, Q........................................... 128

xvi

Figure 4.6: Plots of linear relationship of coalescing plate separator with respect

to TSS removal efficiency, Esss and influent ISS concentration, C iss

for various flowrates, Q........................... ......................................................... 128

Figure 4.7: Minimum removable particle size by coalescing plate separator, d at

different flowrates, Q.................................................................... .................... 13 1

Figure 4.8: Coalescing plate separator effluent oil concentrations, Ceos at

different influent oil concentrations, C io and flowrates, Q ........ .. ..................... 133

Figure 4.9: Plots ofpolynomial relationship of coalescing plate separator

effluent oil concentrations, Ceos and influent oil concentrations, C io

for various flowrates, Q .................... ......................................... ....................... 133

Figure 4.1 0: Plots of exponentiai relationship of coalescing plate separator

effluent oil concentrations, Ceos and influent oil concentrations, Co

for various flowrates, Q .................................................................................... 134

Figure 4.11: Plots ofpower relationship of coalescing plate separator effluent oil

concentrations, Ceos and influent oil concentrations, C io for various

flowrates, Q....................................................................................................... 134

Figure 4.12: Coalescing plate separator oil removal efficiencies, Eos at different

influent oil concentrations, Cio and flowrates, Q .............................................. 136

Figure 4.1 3: Plots of power relationship of coalescing plate separator oil removal

efficiencies, Eos and influent oil concentrations, Cio for various

flowrates, Q....................................................................................................... 137

Figure 4.14: Plots of polynomial relationship of coalescing plate separator oil

removal efficiencies, Eos and influent oil concentrations, C io for

various flowrates, Q.......................................................................................... 137

Figure 4.15: Effluent oil and TSS concentrations, lubricity and bacteria counts of

Elite CNC recycled spent Mobilcut 102 coolant ....................................... ... .... 139

Figure 4.1 6: Effluent oil concentration of Elite CNC recycled Mobilcut 102

coolant. .......................................................... .. .................................... ..... .. ... .... 140

XVll

Figure 4.17: Effluent TSS concentration of Elite CNC recycled Mobilcut 102

Figure 4.20: Initial concentrations of oil, Cino, SS, Cnss and lubricity, J.ls of fresh

Figure 4.22: Effluent oil levels after filtration, separation and aeration for coolant

Figure 4.23: Effluent TSS levels after filtration, separation and aeration for

Figure 4.24: Effluent friction coefficient after filtration, separation and aeration

Figure 4.25: Effluent concentrations of oil and TSS, and lubricity after filtration,

Figure 4.26: Effluent oil and TSS concentrations, and lubricity (with one

Figure 4.30: Oil and TSS concentrations, lubricity and bacteria counts after each

run for recycled coolant (9 runs with influent adjustment during each

coolant............................................................................................................... 140

Figure 4.18: Effluent friction coefficient of Elite recycled Mobi1cut 102 coolant.. .............. 141

Figure 4.1 9: Effluent bacteria counts of Elite recycled Mobilcut 102 coolant ..................... 141

coolant for different coolant-water dilution ratios ............................................ 142

Figure 4.2 1: Lubricity of fresh coolant at dilution ratio 1: 1 00 for different TSS

concentrations ................................................................................................... 143

at dilution ratio 1: 100 and circulated through MRS for 10 runs ....................... 145

coolant at dilution ratio 1: 100 and circulated through MRS for 10

runs....................................................... ... ......... .. ............................................... 146

for coolant at dilution ratio 1: 1 00 and circulated through MRS for 10

runs.................................................................................................................... 146

separation and aeration for coolant at dilution ratio 1: 1 00 and

circulated through MRS for 10 runs ................................................................. 147

concentration adjustment) ................................................................................. 148

Figure 4.27: Effluent oil concentrations (with one concentration adjustment) ..................... 149

Figure 4.28: Effluent TSS concentrations (with one concentration adjustment) .................. 149

Figure 4.29: Effluent lubricity (with one concentration adjustment) .................................... 150

run) .................................................................................................................... 151

XVlll

I

Figure 4.31: Effluent oil concentrations after filtration, separation and aeration for

recycled coolant (9 runs with influent adjustment during each run) ..... ........... 152

Figure 4.32: Effluent TSS concentrations after filtration, separation and aeration

for recycled coolant (9 runs with influent adjustment during each

run) .... .................................................................................................. .. ............ 152

Figure 4.33: Effluent lubricity after filtration, separation and aeration for recycled

coolant (9 runs with influent adjustment during each run) ............................... 153

XIX

I

List of Notations

Symbol Unit Notation

JL mm elongation of spring

Lip Pa net pressure drop over the length of the distributor

Liphole Pa average pressure drop across the inlet holes

LlT °c change in temperature

c mm roughness of pipe

8 ° angle of inclination for coalescence plate

J.l Pa.s dynamic viscosity of continuous liquid

J.lmd Pa.s dynamic viscosity of diluted metalworking fluid

J.ls dimensionless friction coefficient

J.lse dimensionless effluent friction coefficient of metalworking fluid

J.lsea dimensionless effluent friction coefficient of metalworking fluid from aeration unit

/1se! dimensionless effluent friction coefficient of metalworking fluid from filtration unit

J.lses dimensionless effluent friction coefficient of metalworking fluid from coalescence separator

J.lsi dimensionless influent friction coefficient of metalworking fluid

v m2/s kinematic viscosity = p/J.!

p kglm3 mass density of continuous liquid

pc kglm3 mass density of metal chips (Aluminum)

Pmd kglm3 diluted MWF density

po kglm3 mass density of hydraulic oil

xx

I

Pslo kglm3

mass density of solid particles or oil droplets

¢ dimensionless shape factor (oil droplet and solid particle)

Ac m 2

inlet perforated-pipe cross-sectional area

Ahole m 2

total inlet hole area of the distributor

Ap m 3 plan area of coalescence separator

a m coalescing plate top view area width

C mglL concentration of oil or total suspended solids

Ceoa mglL effluent oil concentration from aeration unit

Ceo! mglL effluent oil concentration from filtration unit

Ceas mglL effluent oil concentration from coalescence separator

CtSSQ mglL effluent suspended solids concentration from aeration unit

Cess! mglL effluent suspended solids concentration from filtration unit

Cesss mglL effluent suspended solids concentration from coalescence separation

Cio mglL influent oil concentration

CUS mglL influent suspended solids concentration

Co mglL concentration of oil

Cp J/g.oC specific heat

Css mglL concentration of total suspended solids

d m diameter of solid particle or oil droplet

D m diameter of coalescence separator

Db m outlet baffle diameter

Di m inner diameter of coalescence frustum

Do m outer diameter of coalescence frustum

XXI