Crystallization

Preface


1. Crystallography of Sucrose


1. Introduction


2. Characterization of a Crystal


3 . History of and Introduction to Crystallography

a. The Morphology of Crystals

b. The Symmetry of Crystals

c. Indexing of Crystal Faces


4. Crystallography of Sucrose

a. Crystallographic Zones

b. The Stereographic Projection


5 . Forms of Sucrose Crystals


6. Physical Properties and Internal Structure of Sucrose Crystals


7. Distribution of Impurities in Sucrose Crystals


8. Crystallographic Comments Upon Cane Raw and Refined Sugars

a. RaW

b. Refined


9. Particle Sizes of Granulated and Raw Sugars


10. Determination of M.A. and C.V.

Bibliography


2. The Solubility of Sucrose in Impure Solutions


1. Introduction


2. Solubility Determination


3. Three Component Sucrose Solutions


4. Multi-Component Sucrose Solutions


5. Sucrose Double Compound Formation


6. The Phase Rule and Phase Equilibrium Diagrams


7. Ternary Systems with Two Liquid Phase Solutes

Bibliography


3. Nucleation in Supersaturated Sucrose Solutions


1. Introduction


2. General. Nucleation and Growth


3. Nucleation Theory as Applied to Sugar Solutions

a. Supersolubility

b. Modern Theory


4. Experimental Methods and Results

a. Nucleation Experiments

b. Impurities

c. Foreign Particles

d. False Grain

e. Graining Particles

Bibliography


4. Kinetics of Crystallization Growth of Crystals


1. Introduction


2. Methods

a. General

b. Rate of Growth by Measurement of the Crystal

c. Rate of Growth by Measurement of the Solution

d. Experimental Variables


3. Rate of Growth in Pure Solutions

a. Concentration

b. Temperatures

c. Stirring

d. Mechanism of growth


4. Impurities

a. General

b. Activity Theory

c. Factory Work


5. Dissolution

Bibliography


5. Chemistry of Crystallization


1. Introduction


2. Decomposition of Sucrose During the Crystallization Process


3. Decomposition of Reducing Sugars


4. Reactions of Organic Nonsugars


5. Phenomena Related with the Different Types of Inorganic Nonsugars

a. How is the Presence of Inorganic Suspended Solids Demonstrated in Commercial Sugars?

b. Different Methods of Determining the Amount of Insoluble Nonsugars in Molasses and C-Sugars


6. Nonsugars Affecting the Crystallization of Sugars


7. Phenomena Related with the Dissolution and Regrowth of Sucrose Crystals


8. Effect of Precipitated Nonsugars on the Purity of Centrifuged Sugar

Bibliography


6. Control Methods and Equipment in Sugar Crystallization


1. Introduction


2. Development of Control Methods


3. Importance of Control Equipment


4. Basic Data and Definitions

a. Solubility of Pure Sucrose

b. Solubility of Impure Sugar Solutions

c. Saturation Coefficient

d. Boiling Point Elevation - Pure Sucrose Solutions

e. Boiling Point Elevation - Impure Sugar Solutions

f. Supersaturation - Pure Sucrose Solutions

g. Supersaturation - Impure Sugar Solutions


5. Pan Control Equipment

a. Control of Absolute Pressure

b. Measurement of Boiling Point Elevation

c. Indication and Measurement of Supersaturation

d. Measurement of Fluidity

e. Measurement of Massecuite Level


6. Automatic Control Equipment


7. Summary

Bibliography


7. Application of the Conductivity Method to Control the Crystallization Process and Seeding Technique


1. Introduction


2. The Use of the Cuitometer as Operational Control Instrument

a. The Judgment of the Pan Boiler

b. Viscosity and Conductivity

c. Specific Conductance of Sugar Solutions

d. Mathematical Relation of Viscosity and Conductance

e. Supersaturation, Viscosity and Conductance

f. Conductance and Technical Sugar Crystallization

g. Electrode Cells in Technical Conductivity Control

h. Magnitude of Conductance in Technical Raw Sugar Crystallization

i. Commercial Conductivity Control Equipment

j. Application of Conductivity Control in Different Countries

k. Application of Conductivity Determinations on the Pan Floor

l. Recorded Conductivity Charts of Boilings in Cane Sugar Mills

m. Modification of the Conductivity Control Method


3. Graining of Low Grade Boilings in Raw Sugar Mills

a. Graining of Low Grade Boilings with Powdered Sugar

b. What Kind of Powdered Sugar Should be Used?

c. The Use of Fondant Sugar as Primary Seed for Low Grade Boilings

d. Standard Technique for Making a Slurry of Seed Grain in Organic Solvents by Milling

e. Systems of Grinding Sugar in Organic Fluids to be Used as Seed Grain

f. Different Techniques of Grinding

g. A New System of Special Seeding of the Footing to be Used for C-Strikes

h. When must the Seed Slurry be Introduced in the Pan?

Bibliography


8. Determination of Heat Transmission as an Indirect Method for the Determination of the Viscosity and Supersaturation of Technical Sugar Solutions.L. BOSWORTH, Sydney


1. Introduction


2. Relation Between Viscosity and Supersaturation


3. The Measurement of Heat Transmission


4. Theory of the Electrical Instrument


5. Heat Transmission Under Static Conditions


6. Heat Transmission Under Dynamic Conditions


7. Relation Between Viscosity and Velocity of Circulation


8. The Heat Transmission Recorder

Bibliography


9. Technology of Sugar Crystallization


1. Introduction


2. The Technology of Crystallization of Granulated Sugars


3. The Aims of Sugar Crystallization


4. Desugaration of Boilings and Nonsugar Circulation


5. Development of the Technology of Sugar Crystallization


6. The Crystallization Installation Consists of a Number of Interrelated Equipment Units


7. Fundamentals in the Practice of Sugar Boiling


8. The Significance of Circulation on Supersaturation


9. Feeding of Pans


10. Crystallization of Final Product Boilings


11. Application of Conductivity Control for the Crystallization Process


12. The Conductivity of Technical Sugar Solutions at Saturation Point


13. Supersaturation in Technical Sugar Crystallization


14. Technical Control Instrument for Conductivity Control


15. The Evaporating Surface in Vacuum Pans


16. Technological Investigations on the Crystallization Process

Bibliography


10. Evaporation and Circulation in the Crystallization Process


1. Introduction


2. Effective Driving Forces

a. Evaporation

b. Crystallization

c. Circulation


3. Effective Resistances

a. Evaporation

b. Crystallization

c. Circulation


4. The Effect of Temperature on Crystallization and Circulation


5. Measurements of Pan Circulation


6. Measurement of the Circulation Pattern


7. Circulation Patterns and their Interpretation

Bibliography


11. Natural and Mechanical Circulation in Vacuum Pans with Performance Data and Tests


1. Circulation in Vacuum Pans

a. Introduction

b. Downtakes and Tubes of Calandria Pans

c. Coil Pans

d. Ring Type Calandrias

e. The Shape of the Bottom

f. The Steam Side of the Heating Surface

g. Floating Calandrias

h. Supplemental Vents

i. How Fast is Natural Circulation?

j. Temperature Conditions in Vacuum Pans

k. Boiling Point Rise for 60 Purity

l. Hydrostatic Head Loss

m. Boiling Temperature Graph

n. Temperature-Pressure Graphs for Refinery Strikes

o. Significant Observed Fact on Pan Temperatures

p. Pan Temperature Investigations

q. The Real Mechanism of Natural Circulation

r. Conductivity of Massecuite


2. The Rehabilitation of Mechanical Circulation

a. Introduction

b. Old Circulators

c. Necessity of Mechanical Circulation

d. Basis of Design

e. Speed and Power Requirements

f. Benefits of Mechanical Circulation

g. Comparative Rating Curves

h. Quality of Crystals

i. Summary


3. Equipment and Operating Conditions for Satisfactory Vacuum Pan Performance

a. Introduction

b. Stable Conditions

c. Vacuum Control

d. Stable Steam Pressure

e. Instrumentation

f. Supersaturation Control

g. Steam Flow Meter

h. Crystallization

i. Significant Observations on Pan Operation

j. Vacuum Pan Tests


4. Application of Mechanical Circulators in the Sugar Industry Around the World

Bibliography


12. Crystallization of Massecuites by Cooling


1. Introduction


2. Solubility of Sucrose in Pure and Impure Solutions


3. The Rate of Crystallization of Sucrose


4. History of the Crystallizer Station


5. Types of Crystallizers and Cooling Systems


6. Construction Material and Shape of Cooling Elements


7. Heat Transfer Coefficients for Different Types of Massecuite


8. Speed of Rotation of Cooling Elements for Different Types of Massecuite


9. Crystallizer Drive and Power Consumption


10. Crystallizer Control and Control Instruments


11. Maintenance of Cooling Systems in Crystallizers


12. Time Needed for the Efficient Cooling of Different Types of Massecuite


13. Reduction in Total Massecuite Quantity by Rapid Cooling of First Boilings. Simplification of Boiling Scheme

a. Four-Boiling Scheme

b. Three-Boiling Scheme


14. Secondary Grain Formation in Crystallizers


15. Installation of Crystallizers. The Use of Massecuite Pumps

Bibliography


13. Conditioning of Massecuites in Crystallizers


1. Introduction


2. Supersaturation

a. Coefficient of Supersaturation

b. Saturation Temperature

c. Use of Saturoscope

d. Supersaturation in Crystallizer Practice


3. Viscosity

a. Rheology of Molasses and Massecuites

b. Effect of Nonsugar Constituents on Viscosity

c. Effect of Total Solids on Viscosity of Molasses

d. Effect of Temperature on Viscosity of Molasses

e. Relation of Purity of Molasses to Viscosity

f. Relation of Reducing Substances-Ash Ratio to Viscosity


4. Crystal Content and Size

a. Crystal Content

b. Crystal Size


5. Crystal Movement


6. Cooling


7. Reheating and Diluting


8. Conductivity Control


9. Molasses Exhaustibility


10. Summary and Conclusions

Bibliography


14. Maximum Recovery of Crystallized Sucrose from Low Grade Boilings


1. Introduction


2. Phase Rule Considerations

a. Eutectic Mixture Versus Saturated (Metastable) Solution of Sucrose

b. The Estimation of Fine Grain in Final Molasses According to Kalshoven


3. Hydrated Sugar-Salt Compounds


4. Solubility of Sucrose in Solutions Also Containing Nonsucrose Components


5. The Rate of Crystallization of Sucrose from Impure Solutions


6. Some Practical Considerations


7. Exhaustibility of Final Molasses

a. Statistical Target Purities

b. Methods of Judging Purities of Final Molasses Based on Exhaustibility Tests

c. Viscosity and Exhaustibility

d. Progress in Molasses Exhaustion

Bibliography

Author Index

Subject Index