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Dissertação James Cook University (em inglês)
Tipologia: Teses (TCC)
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Kent, Geoffrey A (2003) Increasing the capacity of Australian raw sugar factory milling units. PhD thesis, James Cook University.
Thesis submitted by
Geoffrey Alan KENT BE (Mech Hons) UQ MIEAust CPEng RPEQ
in September 2003
for the degree of Doctor of Philosophy in the School of Engineering (Mechanical Engineering) James Cook University
Increasing the capacity of Australian raw sugar factory milling units (^) iii
Electronic copyElectronic copyElectronic copyElectronic copy
I, the undersigned, the author of this work, declare that the electronic copy of this thesis provided to the James Cook University Library is an accurate copy of the print thesis submitted, within the limits of the technology available.
Signature Date
Increasing the capacity of Australian raw sugar factory milling units (^) iv
Statement of sourcesStatement of sourcesStatement of sourcesStatement of sources
I declare that this thesis is my own work and has not been submitted in any form for another degree or diploma at any university or other institution of tertiary education. Information derived from the published or unpublished work of others has been acknowledged in the text and a list of references is given.
Signature Date
Increasing the capacity of Australian raw sugar factory milling units (^) vi
Cook University are acknowledged for their assistance with the two-roll mill experiment. Mr Neil McKenzie of the Sugar Research Institute, Miss Letitia Langens formerly of the Sugar Research Institute and Mr Kevin Wardrop, Mr Bob Watters, Mr Jeff King Koi and the staff of Mulgrave Central Mill Company Limited for their assistance with the factory mill experiment.
Fifthly, the author thanks his supervisors A/Prof Jeff Loughran of James Cook University and Dr Vic Mason formerly of the Sugar Research Institute, along with Dr Mac Kirby of CSIRO, Dr Floren Plaza and Dr Matt Schembri of the Sugar Research Institute, Dr Chris Downing formerly of the Sugar Research Institute, Dr Clayton Adam formerly of Queensland University of Technology and Mr Tom Davis, Mr John Sawyer and Mr John Li of Worley FEA for the fruitful discussions and advice received throughout this investigation.
Lastly, the author thanks his wife Karen and children Natasha and Christopher for their support and encouragement throughout this long investigation.
Increasing the capacity of Australian raw sugar factory milling units (^) vii
AbstractAbstractAbstractAbstract
This thesis reports on an investigation to identify methods to increase the capacity or throughput of the six-roll roller mills used in Australia to extract sugar from sugarcane. The approach taken was to gain an understanding of the factors affecting mill throughput through the application of the computational milling model, developed in recent years at James Cook University. The computational milling model is based on general equations of force equilibrium and continuity and a general description of sugarcane material behaviour.
The development of the throughput model was conducted in stages. Firstly, an experiment was conducted on a laboratory two-roll mill to gain an understanding of the factors affecting throughput on this simple milling geometry. A two-roll computational model was constructed to predict the observed behaviour, accounting for all mechanisms identified from the experimental results. Secondly, a three-roll computational model was constructed which was sufficient to describe the throughput behaviour of the factory six-roll mill. An experiment was conducted on a factory six- roll mill to provide data to validate the model. The three-roll computational model was tested across the range of geometries and operating conditions known to exist in Australian factories and its throughput predictions were tested against throughput measurements.
The three-roll computational model was used to identify the main factors affecting mill throughput and was used to construct a data set across a wide range of parameter values. The data set was used in a multiple regression analysis to develop an empirical model that could readily be used to identify conditions for maximum throughput.
The computational and empirical models developed during this investigation were shown to predict throughput better than existing models. Conditions for maximum
Increasing the capacity of Australian raw sugar factory milling units (^) ix
ConConConContentstentstentstents
Statement of access .........................................................................................................ii Electronic copy...............................................................................................................iii Statement of sources ...................................................................................................... iv Acknowledgements ......................................................................................................... v Abstract..........................................................................................................................vii Contents .......................................................................................................................... ix Tables ............................................................................................................................ xvi Figures.........................................................................................................................xviii Symbols ....................................................................................................................... xxiv 1 Introduction ......................................................................................................... 1 1.1 Introductory remarks.................................................................................. 1 1.2 Overview of the milling process and milling equipment ........................... 1 1.2.1 Description of sugarcane ................................................................ 1 1.2.2 Description of the milling process .................................................. 3 1.2.3 Description of a milling unit........................................................... 5 1.2.4 Definition of milling terms ............................................................. 7 1.3 The need to increase milling unit capacity............................................... 12 1.3.1 The Australian raw sugar industry................................................ 12 1.3.2 Maintaining industry viability ...................................................... 13 1.3.3 The path to processing larger crops .............................................. 14 1.3.4 Increasing milling unit capacity.................................................... 14 1.4 Overview of the thesis.............................................................................. 14 1.5 Concluding remarks ................................................................................. 16 2 Mill throughput literature review .................................................................... 17 2.1 Introductory remarks................................................................................ 17 2.2 Review of sugarcane milling unit throughput research............................ 17 2.2.1 Introductory remarks..................................................................... 17
2.3 Review of milling unit throughput research outside the sugarcane industry
Increasing the capacity of Australian raw sugar factory milling units (^) xiii
Appendix C Permeability measurements for comparing measurement techniques Appendix H Data set used for the development of the new empirical feeding model
- 2.2.2 Empirical models - 2.2.3 The two-roll mill........................................................................... - geometry 2.2.4 Extending the two-roll mill theory to more complex milling - 2.2.5 The six-roll mill - 2.2.6 Concluding remarks...................................................................... - 2.3.1 Introductory remarks..................................................................... - 2.3.2 Roller mill applications................................................................. - 2.3.3 Throughput models for roller mills............................................... - 2.3.4 Concluding remarks...................................................................... Increasing the capacity of Australian raw sugar factory milling units (^) xvi
TablesTablesTablesTables
Table 3.1 Comparison of Jenkins and Murry model results from Figure 3.3 .......... 40 Table 5.1 Results of the parameter estimation process for the two assumed values of coefficient of friction................................................................................ 75 Table 5.2 Estimated parameters from the steady state permeability experiment..... 99 Table 5.3 Estimated parameters from the transient permeability experiment........ 101 Table 6.1 Roll dimensions for the two-roll mill experiments ................................ 110 Table 6.2 Levels of each factor explored in the two-roll mill experiment............. 111 Table 6.3 Analysis of variance of Murry’s feed speed ratio for the two-roll mill experiment.............................................................................................. 113 Table 6.4 Analysis of variance of Murry’s feed speed ratio for the two-roll mill experiment treating results from tests 3, 13 and 19 as missing values .. 118 Table 6.5 Analysis of variance of Murry’s feed speed ratio for the 40º contact angle tests from the two-roll mill experiment.................................................. 119 Table 6.6 Analysis of variance of Murry’s feed speed ratio for the 120 mm nip setting tests from the two-roll mill experiment ...................................... 121 Table 6.7 Results of the solid phase material parameter estimation process ......... 136 Table 6.8 Analysis of variance of the four estimated solid phase material parameters ................................................................................................................ 137 Table 6.9 Solid phase material parameters selected to be representative of the prepared cane used in the two-roll mill experiment............................... 141 Table 6.10 Results of the permeability parameter estimation process..................... 143 Table 6.11 Main effect of each experimental factor on Murry’s feed speed ratio... 154 Table 7.1 Range of values for cos α in Solomon’s experiments ........................... 170 Table 7.2 Analysis of variance of Murry’s feed speed ratio for Solomon’s factorial experiment.............................................................................................. 175 Table 8.1 Roll dimensions for Mulgrave’s #5 mill ................................................ 202 Table 8.2 Factors and factor levels explored in the experiment............................. 207
Increasing the capacity of Australian raw sugar factory milling units (^) xviii
FiguresFiguresFiguresFigures
Figure 1.1 Cross-section of a cane stem (after Payne 1968) ....................................... 2 Figure 1.2 Typical layout of a milling train with four milling units (from Neill, McKinnon & Garson 1996) ....................................................................... 5 Figure 1.3 Typical layout of a milling unit (from Neill, McKinnon & Garson 1996) 6 Figure 1.4 Roll dimensions.......................................................................................... 8 Figure 1.5 Nip and chute settings and contact angles.................................................. 9 Figure 2.1 Two-roll mill geometry ............................................................................ 20 Figure 2.2 Forces acting on a strip of bagasse in a two-roll mill .............................. 23 Figure 3.1 Feed chute dimensions ............................................................................. 36 Figure 3.2 Comparison of the Jenkins and Murry and 1997 effectiveness measurements with Jenkins and Murry model predictions ...................... 39 Figure 3.3 Comparison of the difference in effectiveness of pairs of milling units with the predicted difference using the Jenkins and Murry model .......... 40 Figure 4.1 Stresses acting on an elemental volume................................................... 44 Figure 4.2 Fluid flowing through the elemental volume ........................................... 46 Figure 4.3 The yield surface for the simplified Drucker-Prager cap material model 54 Figure 4.4 A comparison of constant λ and constant λ 1 hardening rules for modelling uniaxial compression................................................................................ 58 Figure 5.1 Uniaxial compression test cell used to provide experimental data for material parameter determination ............................................................ 65 Figure 5.2 Uniaxial compression test cell used to provide experimental data for material parameter determination (second configuration) ....................... 66 Figure 5.3 Typical experimental and model results for uniaxial compression tests obtained from parameter estimation process for solid phase material parameters ................................................................................................ 74
Increasing the capacity of Australian raw sugar factory milling units (^) xix
Figure 5.4 Results of sensitivity analysis for solid phase material parameters showing the relative change in the objective function for a change in the material parameters .................................................................................. 77 Figure 5.5 Steady state permeability test apparatus (Downing 1999)....................... 80 Figure 5.6 Typical experimental results for the steady state permeability tests........ 84 Figure 5.7 Regression fit to determine the permeability parameters for typical experimental results for the steady state permeability tests ..................... 86 Figure 5.8 Typical experimental and model results for indirect permeability tests obtained from parameter estimation process for fluid phase material parameters ................................................................................................ 94 Figure 5.9 Results of sensitivity analysis for permeability parameters showing the relative change in the objective function for a change in material parameters ................................................................................................ 96 Figure 5.10 Results from the steady state permeability experiment............................ 99 Figure 5.11 Void ratio and permeability relationships from the transient permeability experiment.............................................................................................. 101 Figure 5.12 Comparing permeability measurements between steady state (black curves) and transient (red curves) testing methods ................................ 102 Figure 6.1 Two-roll mill layout ............................................................................... 108 Figure 6.2 Mean values of Murry’s feed speed ratio for each level of each factor for the two-roll mill experiment with all results included ........................... 114 Figure 6.3 Significant interactions identified in the analysis of variance of Murry’s feed speed ratio for the two-roll mill experiment................................... 115 Figure 6.4 Mean values of Murry’s feed speed ratio for the two-roll mill experiment with tests 3, 13 and 19 removed............................................................. 116 Figure 6.5 Mean values of Murry’s feed speed ratio for each level of each factor for the 40º contact angle tests from two-roll mill experiment ..................... 120 Figure 6.6 Mean values of Murry’s feed speed ratio for each level of each factor for the 120 mm nip setting tests from two-roll mill experiment.................. 122 Figure 6.7 Roll load history for the two-roll mill experiment’s test 6..................... 123 Figure 6.8 More realistic flow path for the surface of the bagasse mat .................. 125 Figure 6.9 Forces acting on a strip of bagasse in a two-roll mill under conditions of forward slip ............................................................................................ 127