CLEANING OF TOOTHPASTE FROM PROCESS EQUIPMENT BY FLUID FLOW AT LABORATORY AND PILOT SCALES. BY PAMELA ANNE COLE A thesis submitted to the University of Birmingham for the degree of Engineering Doctorate School of Chemical Engineering College of Engineering and Physical Sciences University of Birmingham September 2011 Abstract ABSTRACT Cleaning studies were performed to remove toothpaste by fluid flow at different temperatures and velocities to mimic CIP (Cleaning-In-Place) processes on toothpaste coated coupons at laboratory scale and fully filled pipeline at pilot scale (different lengths and diameters). The cleaning time was reduced by increasing the velocity and temperature of the water, however no further time benefit was seen above 40°C. The adhesive force for different pastes calculated from micromanipulation data followed the same trend as cleaning times on the laboratory cleaning rig. This cleaning data for the different paste formulations had a logarithmic relationship with the viscosity term from the Herschel-Bulkley rheological model. Removal of toothpaste from pipes occurred by the core of the paste being removed from the centre of the pipe to leave a thin coating on the pipe wall, which was then eroded by flow. Pipes of lengths between 0.3 m and 2 m (47.7 mm diameter pipe) showed no difference in cleaning time. The rate limiting process was removal of the thin wall coating and therefore not a function of length. An inverse wall shear stress relationship with cleaning time was found to represent all the data, at all scales and under all conditions. i Dedications and Acknowledgements DEDICATIONS AND ACKNOWLEDGEMENTS I gratefully acknowledge financial support from GSK and the EPSRC. Thank you for the support and guidance of my supervisors: Prof. Peter Fryer, Dr. Phil Robbins, Nigel Armitage, Natalie Salmon and Eddie Owen. I really appreciate the professional support and friendship of those at the University of Birmingham Chemical Engineering Department, and GlaxoSmithKline Maidenhead & Weybridge sites and all the ZEAL Consortium members who helped me to gain experience and develop professionally, as well as sharing some great nights out. In particular I would like to thank Kylee, Konstantia, Kathleen, Eddie and Phil for helpful discussions and camaraderie during toothpaste related adventures and also to Bunmi, Tim and Ishara for their assistance in the Pilot Plant. I am so grateful to ALL my friends and family for your patience and support, in particular my family: Mum, Dad, Rowena, Davina, Matthew, Louise, Taylor & Grandma, and Sam & Lynda, for providing endless cups of tea, encouragement and genuine understanding. I promise that I will never again turn up at your houses and events with my thesis in an unwritten state. ii Contents CONTENTS ABSTRACT ............................................................................................................................................ I DEDICATIONS AND ACKNOWLEDGEMENTS .......................................................................... II CONTENTS ......................................................................................................................................... III TABLE OF FIGURES ...................................................................................................................... VII ABBREVIATIONS ............................................................................................................................ XX CHAPTER 1: INDUSTRIAL CLEANING ........................................................................................ 1 1.1. Thesis Aims ....................................................................................................................... 1 1.2. Introduction to ZEAL ........................................................................................................ 3 1.3. The cleaning map .............................................................................................................. 4 1.4. Toothpaste ........................................................................................................................ 6 1.5. Costs and consequences of failure to clean ....................................................................... 7 1.6. Plant design ....................................................................................................................... 8 1.7. The methods of industrial cleaning ................................................................................... 8 1.8. Establishing a CIP regime ............................................................................................... 10 1.9. Cleaning regime stages .................................................................................................... 11 1.10. CIP unit ...................................................................................................................... 12 1.11. Benchmarking cleaning ................................................................................................... 14 1.12. Optimising industrial cleaning ........................................................................................ 15 1.13. Levels of cleanliness and cleaning monitoring ................................................................ 16 1.14. CIP without detergent ...................................................................................................... 17 1.15. CIP sequencing ................................................................................................................ 17 1.16. Factory CIP Layout ......................................................................................................... 18 1.17. Thesis structure ................................................................................................................ 20 CHAPTER 2: FACTORS AFFECTING FOULING & CLEANING OF A DEPOSIT REMOVED BY FLUID MECHANICS ............................................................................................ 22 2.1. Infrared spectroscopy ...................................................................................................... 25 2.2. Micromanipulation .......................................................................................................... 26 2.3. Rheology……………...................................................................................................... 29 2.3.1. Yield stress ...................................................................................................................... 30 iii Contents 2.3.2. Rheological models .......................................................................................................... 30 2.3.3. Viscoelastic properties of toothpaste ................................................................................ 31 2.4. Laboratory scale cleaning studies - flat plate flow cell (Coupon rig) .............................. 32 2.5. Fluid cleaning .................................................................................................................. 34 2.6. Soaking and hydration studies ......................................................................................... 35 2.7. Jetting …………………………………………………………………………… 35 2.8. Pipe flow…………… ...................................................................................................... 36 2.8.1. Wall shear stress .............................................................................................................. 37 2.9. Recirculation zones ......................................................................................................... 38 2.10. Non uniform flow ............................................................................................................ 38 2.11. Other fluid cleaning methods .......................................................................................... 38 2.12. Chemical cleaning ........................................................................................................... 39 2.13. Temperature ..................................................................................................................... 41 2.14. Cleaning studies .............................................................................................................. 41 2.15. Pilot – scale studies ......................................................................................................... 43 2.16. Pilot scale – measurements .............................................................................................. 44 2.17. Summary……….............................................................................................................. 45 CHAPTER 3: MATERIALS AND METHODS .............................................................. 47 3.1. Material characterisation - toothpaste ............................................................................... 49 3.2. Structural characterisation - infrared spectroscopy .......................................................... 49 3.3. Structural characterisation - rheology ............................................................................... 53 3.4. Structural characterisation - Micromanipulation .............................................................. 58 3.5. Cleaning equipment .......................................................................................................... 60 3.5.1. Ab Aziz PIV Rig ..............................................................................................................