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Measurement of Cane Preparation

Measurement of Cane Preparation. Milling Seminar 11 May 2005 Peter Rein Audubon Sugar Institute. Measurement of Cane Preparation. Cane Preparation has a very large effect on extraction and moisture content of bagasse It is important to measure preparation Methods of measurement include:

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Measurement of Cane Preparation

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  1. Measurement of Cane Preparation Milling Seminar 11 May 2005 Peter Rein Audubon Sugar Institute

  2. Measurement of Cane Preparation • Cane Preparation has a very large effect on extraction and moisture content of bagasse • It is important to measure preparation • Methods of measurement include: • Bulk density • Mean particle size • Extent of breakage of cells

  3. Sampling • The measurement is only as good as the sampling • It is difficult to get a representative sample, unless a full-width hatch sampler is used • Sampling from the top layer gives a biased sample (classification of fines) • Cane is non-homogenous and requires that a number of samples across the conveyor at different depths be taken • Mixing and sub-sampling is difficult • If the sample is not well-prepared, biased sampling sometimes omits large chunks

  4. Mean Particle Size • Particle size measurement by screening is possible • The sample needs to be dried first • The sieving efficiency is low, because of the large length/diameter ratio of the particles • The results are technique and equipment dependent • Reliable measurements can be obtained from a standardized procedure • May be expressed as a mean particle size or a “fineness figure”

  5. Bulk Density • Compressing a sample under standard conditions gives the bulk density, which depends on the cane preparation. • Fine preparation leads to a high bulk density • Crawford (Australia) compressed a 15 lb sample at 15 psi for 5 minutes • Pressure chosen so that no juice expression occurs

  6. Correlation between bulk density and fineness (Crawford 1970)

  7. Measurement of Cell Breakage • This is the best method, since it characterizes the preparation in terms of its extractability • Cane and water tumbled together for a standard length of time, and the sucrose content of the extract measures the extent of cell breakage and the availability of juice • If the ratio of water to sample is the same in the tumbler and in the cold digester, PI = 100.(tumbler conc.)/(digester extract conc.) • Cane sample is small (~ 500 g) and needs replicates

  8. Equipment Used

  9. Problems • Different test conditions lead to different results • Test conditions in Australia, Hawaii, South Africa and Louisiana are all different • PI is affected by excessive trash in cane • Pi is not reliable with coarse preparation; should not be used if PI < ~80

  10. Comparison of Test Conditions

  11. Conclusions • It is worthwhile to measure the degree of preparation routinely • PI is probably the best routine method • It is not a precise measure, but the average over time gives the best indication of preparation • In making comparisons, be aware which method is being used • PI (SA) is greater than POC (Austr.) by about 5 units • PI (La) is greater than PI (SA) by about 5 units

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