Lynne Wong's PhD thesis

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Rein (1975) investigated the effects of fibre and pol % cane on the extraction achieved by milling tandems, by using a statistical approach. He showed that extraction is adversely affected by high fibre levels but improves as pol % cane rises. A cost analysis done by Cargill (1976) showed the following: • Reducing tops and trash in cane by 3% would increase throughput (tons cane per hour TCH) by 9% with the same installed capacity, and reduce transport costs by 3%. • Decreasing trash in cane by 1% would increase the overall recovery of pol by 0.3%. Scott (1977) carried out full-scale tests at two milling tandems to measure the effect of fibre % cane, trash and tops in cane on throughput. Except for tops in cane, he obtained statistically significant regressions: TCH = 203.3 – 5.3 fibre % cane TCH = 134.3 – 3.0 trash % cane The overall results showed that the crushing rate is reduced by about 4% for a unit rise in fibre % cane and by 2.2 to 3.0% for a unit rise in trash % cane. Reid and Lionnet (1989) carried out full-scale processing of different types of harvested cane: clean stalk, stalk without removal of tops, trash, and tops and trash. Compared to clean stalk, the results showed that: • The mill throughput with unburnt, untopped cane was 30% less than that with burnt, topped cane, while that with unburnt, topped cane was 22% less. • Compared to burnt, topped cane, boiling house recovery was predicted to drop by 6% with unburnt, untopped cane. Similar results were obtained when Lionnet (1992b) carried out tests with a diffuser instead of the milling tandems. The effect of trash on milling has been studied by numerous workers. Most of the studies either dealt with dry trash only or a fixed pre-defined proportion of dry trash, cane tops and soil, while many others were conducted as factory trials. Using an experimental threeroller mill equipped with rollers of 10 inches diameter and 14 inches long with a hydraulic pressure of 30 tons, Arceneaux and Davidson (1944) crushed clean cane of several varieties to which were added separately green and dry trash in amounts of 2.5, 5.0 and 7.5%, with maceration water applied four times at 20% on the cane. They found that green 21
leaves increased the level of impurities in the juice but had little influence on the sucrose retention in the bagasse, while the opposite was true for dry trash, as they showed that green leaves contain twice as much soluble solids as did the same quantity of dry matter from dry leaves. This laboratory scale experiment had the merit of adding accurately measured amount of extraneous matter to clean cane, and determining the quality of the resulting cane, bagasse and juice. There was no evidence to suggest that the prevailing experimental conditions would be different from those which may be expected under industrial conditions. Tsai et al. (1961) also used an experimental mill to crush mixtures of various types of extraneous matter with clean cane, and found the purity of the crusher juice extracted dropped by 0.5 – 0.6 unit for each unit of extraneous matter added irrespective of whether it was dry trash, green leaves, tops, roots, dead stem or soil. With a similar experimental mill, Legendre and Irvine (1974) studied the effects of a mixture of 40% dry trash and 60% cane tops in increments of 0, 5, 10, 20 and 30% by mass of cane on milling quality such as fibre % cane, juice extraction and purity of juice extracted. Hemaida et al. (1977) also investigated the effects of dry and green leaves at 0, 2.5, 5.0 and 7.5% cane on mixed juice extraction, bagasse % cane, sucrose lost in bagasse % cane and mixed juice purity. All the above workers also estimated the theoretical sugar recovery and sucrose loss in molasses. 1.5.3 Effects of cane quality on cane processing in Mauritius The analysis of factory performance data conducted by Wong Sak Hoi and Autrey (1997) over the period 1960 to 1996 showed that the increase in extraneous matter in cane has increased sucrose losses in filter cake, bagasse and molasses. This is in contrast to the fact that over the same period sucrose extraction at the milling plant (mill extraction) has actually been improved as a result of heavy investment in cane preparation equipment and in milling tandems, and by the application of more imbibition water % fibre. One favourable aspect of the extra trash in cane is the increase in the mass of bagasse % cane by 4 units, which is good for energy production. However, this advantage is outweighed by the capital investment in the installation or modification of various factory equipment such as the feed table, heavy duty shredders, juice screening system and modern boilers, and by higher maintenance costs to off-set the effect of extraneous matter on factory performance. 22
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THE BRIX-FREE WATER CAPACITY AND SO
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dissolved and hydrated waters, and
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ACKNOWLEDGEMENTS I am particularly
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Page 1.5 THE DELETERIOUS EFFECTS OF
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Page 2.2 THE PHENOMENON OF BRIX-FRE
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Page 3.4.3.3 Cane tops 83 3.4.4 Cha
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4.3.3 Temperature at which Brix-fre
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4.6.1 Materials 143 4.6.1.1 Samples
Page 17 and 18: CHAPTER 6. PROPERTIES OF THE SORBED
Page 19 and 20: APPENDIX 3. CALCULATIONS LEADING TO
Page 21 and 22: LIST OF FIGURES Page Figure 1.1. Fi
Page 23 and 24: Figure 3.1. Glucose and fructose an
Page 25 and 26: Figure 5.11. Residual plots for the
Page 27 and 28: total adsorbed water (m) and the pr
Page 29 and 30: Table 2.18. Moisture content in sug
Page 31 and 32: Page Table 4.4. Results of the dete
Page 33 and 34: Page Table 4.24. Analysis of varian
Page 35 and 36: Page Table 5.13. Table 5.14. Equili
Page 37 and 38: Table 6.3. Heat of sorption of the
Page 39 and 40: GLOSSARY OF TERMS Absorption is the
Page 41 and 42: Filterability of a raw sugar is mea
Page 43 and 44: Sorption is the generic term used w
Page 45 and 46: LIST OF MAIN SYMBOLS Symbol Descrip
Page 47 and 48: s c s Slope of Caurie I isotherm pl
Page 49 and 50: number of 255, and cane land covere
Page 51 and 52: Nouvelle Mon In Trésor ustrie and
Page 53 and 54: Figure 1.3. Cane sampling by core s
Page 55 and 56: In Mauritius, most of the sugar fac
Page 57 and 58: are: cane tops, dry and green leave
Page 59 and 60: 1.4 TRENDS IN CANE QUALITY RECEIVED
Page 61 and 62: campaign was launched to encourage
Page 63 and 64: The level of extraneous matter in c
Page 65 and 66: In Australia (Cargill, 1976), cane
Page 67: The effect of soil on factory perfo
Page 71 and 72: • From 1976 to 1980, when the pro
Page 73 and 74: Clerget purity of molasses 40 Clerg
Page 75 and 76: CHAPTER 2. IMPACT OF EXTRANEOUS MAT
Page 77 and 78: Since the extrapolated purity of mo
Page 79 and 80: Figure 2.1. Jeffco cutter grinder.
Page 81 and 82: 2.1.4 Results The analytical result
Page 83 and 84: Table 2.3. Analytical results of re
Page 85 and 86: Table 2.5. Composition of dry trash
Page 87 and 88: Table 2.7. Predicted factory perfor
Page 89 and 90: Boiling house recovery 91.0 89.8 89
Page 91 and 92: 0 5 10 15 20 % EM in cane y = 0.572
Page 93 and 94: % EM in cane 0 5 10 15 20 0 -2 -4 -
Page 95 and 96: 1 y = 0.020 (% D) R 2 = 1.00 = 0.03
Page 97 and 98: % EM in cane 0 5 10 15 20 0 -2 y =
Page 99 and 100: esulting in 0.015 unit sucrose loss
Page 101 and 102: 2.2.1 Experimental procedure Cane m
Page 103 and 104: filter paper, rejecting the first f
Page 105 and 106: Table 2.9. Effect of increased addi
Page 107 and 108: Table 2.11. Effect of increased add
Page 109 and 110: Table 2.13. Effect of increased add
Page 111 and 112: various components such as stalk fi
Page 113 and 114: in the presence of dry leaves, if c
Page 115 and 116: Table 2.17. Moisture content in sug
Page 117 and 118: CHAPTER 3. SEPARATION OF THE SUGAR
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Table 3.1. It can be seen that the
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Table 3.2. Fibrous physical composi
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R 579 R 570 M 1557/70 M 1400/86 74
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loosen the fibre. The woody core is
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agitate the mixture in the pot, and
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Figure 3.7. Custom-built fibre-pith
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The extraction of fibres starting f
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pre-treatment in a Jeffco cutter-gr
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Figure 3.19. Stalk cake washed free
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not have many dry leaves attached t
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Table 3.5. Masses of cane samples a
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Table 3.7. Masses of cane samples a
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Table 3.9. Masses of cane component
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3 57.6 126.3 23.7 97.2 31.1 53.8 11
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Table 3.12. Material loss (%) from
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3.5.3 Fibre/pith ratios in cane com
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Table 3.15. Effect of extraneous ma
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Snow (1974) investigated the season
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from Figure 2.9 that the change in
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Table 3.18. Fibre % cane results by
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110
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(a). Dry leaf (b). Green leaf (c).
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dry fibre, or a factor, is used in
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Steuerwald (1912) applied sucrose s
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solution/fibre ratio was lowered fr
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leave some residual moisture on the
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instead of 150 g of 10° Brix sucro
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Table 4.2. Determination of Brix-fr
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Table 4.3. Comparison of Brix-free
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Table 4.4. Results of the determina
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In order to test for homogeneity of
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Table 4.7. Results of the repeat de
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The experiment was repeated with th
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e any residual moisture in the samp
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By means of the same technique, Won
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was still hot. Since the filter was
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value determined could be corrected
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Qin and White’s finding was confi
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A sample size of 3.5 g with 75 g co
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Figure 4.4. Fibre samples drying in
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- One large fibre sample (rind) of
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Table 4.18. Brix-free water values/
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Table 4.20. Brix-free water values/
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4.7.3 Statistical analysis It is es
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Table 4.23. Analysis of variance (B
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pointing out that at 52 weeks old,
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The crop of R 570 sampled in 2001 w
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4.7.4. Estimated Brix-free water co
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The main difference in the two sets
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Table 4.27. Predicted Brix-free wat
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4.8 SUMMARY AND CONCLUSIONS An anal
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component parts, and verify the Bri
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3) Thermodynamic, water in equilibr
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Langmuir (1916, 1917, 1918) propose
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to determine the moisture sorption
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Table 5.1. Some commonly used isoth
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Lomauro et al. (1985) found that wi
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and on agricultural products such a
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Bruijn (1963) studied the mass incr
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After measuring the EMC of dry corn
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approached, that is, either by adso
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Table 5.4. Water activity (a w ) of
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5.6.3 Procedure to determine equili
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5.6.4 Results and discussion An exa
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Table 5.8. Equilibrium moisture con
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Table 5.10. Equilibrium moisture co
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Table 5.12. Equilibrium moisture co
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30 o C 45 o C 55 o C 60 o C Water w
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m/m of 96% activity, a w (g/100g dr
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vaporisation generally decreases fr
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30 o C isotherm 45 o C isotherm 55
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4 0 Stalk fibre 5 0 Stalk pith 5 0
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5.6.4.4 Fitting of sorption models
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Table 5.19. Parameters of the sorpt
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Modified GAB Kuhn Iglesias - Chirif
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Table 5.28. Classification of resid
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Stalk fibre Stalk pith Rind fibre 4
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5.6.4.5 Calculated EMC values of re
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Table 5.30. Calculated equilibrium
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m/m of 96% Table 5.32. Calculated e
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Table 5.33. Parameters of the Hailw
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CHAPTER 6. PROPERTIES OF THE SORBED
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where m is the equilibrium moisture
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6.2 THE NUMBER OF ADSORBED MONOLAYE
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6.3 TOTAL SOLID SURFACE AREA AVAILA
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Thus, for each cane component of ea
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abscissa. For each moisture level (
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A similar procedure was followed to
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10 0 Stalk fibre Stalk pith Rind fi
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Moreover, if T β > T hm the proces
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Table 6.5. Characteristic parameter
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Binding energy/kJ (kg mol) -1 2 0 0
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6.8 CALCULATION OF BOUND WATER AND
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The values of K 1 , K 2 and W were
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Table 6.7. Separation of the total
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Table 6.7. (Contd.) Sample 30 o C 4
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3 0 S talk fibre 4 0 Stalk pith 3 0
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3 0 Reconstituted cane at 30 o C 3
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when water is added to dry wood, wh
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It is evident that in some cases ma
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The number of adsorbed monolayers,
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Data in Tables 2.9 and 2.11 show th
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particular fibre is systematically
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Anon. (1985b). Laboratory manual fo
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Blanchi R.H. and A.G. Keller (1952)
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Day D.L. and G.L. Nelson (1965). De
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Heyrovsky J. (1970). Determination
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Kuhn I.J. (1964). A new theoretical
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Madamba P.S., R.H. Driscoll and K.A
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Prinsen Geerligs, H.C. (1897). Stud
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Sing K.S.W., D.H. Everett, R.A.W. H
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Van der Pol C., C.M. Young and K. D
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Lynne Wong's PhD thesis

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