Sugar Seed Slurry in pan boiling of Crystallization|Online Calculator
The sugar crystallization(pan boiling) is one of the important sections in the sugar industry. In crystallization process follows different techniques to form sugar crystal nuclei (grain techniques). Generally, true seeding method is one of the best methods of graining in a pan-boiling scheme. In this method, sugar seed slurry is used for crystal formation.
In a true seeding method, the liquor is concentrated up to it will reach the metastable zone. Then Crystallization is initiated by admitting some very fine sugar seed in the form of a slurry, which provides the nuclei to start the crystallization. The slurry has mixer of organic solvent and very finely ground sugar particles. ( 3 to 5 micron size sugar nuclei).
The basic requirements of organic solvents to be used for sugar seed slurry preparation are as follows.
- a) Boiling point of organic solvent be lower than water.So that after introduction of slurry in pans all organic solvent gets evaporated and crystal get spread well.
- b) Solubility of sucrose in such organic solvent should be minimum or negligible.
- c) Solubility should not give any odor to sugar.
Various methods are used in preparing the seed slurry. Usually, the seed slurry is prepared in precipitation method and ball milling of refined sugar in alcohol for a period of time.
The magma or seed is used as a footing into the batch pan or continuous pans. The size and quality of the magma have placed a significant role in the final crystal size and exhaustion of the massecuite. The uniform size of crystal with the correct estimated quantity of sugar seed slurry dosing is very essential to get good quality magma.
Calculation Process for Sugar Seed Slurry Requirement
Now the estimation of sugar seed slurry to the pan depended on the following parameters.
- a) Generally Grain is prepared in a batch pan and its magma is fed to a continuous pan.
- b) According to dropped magma in batch pan, estimate total production of massecuite from continuous pan.
- c) Requirement of crystal size in final dropping massecuite. ( Generally, For B massecuite the average crystal size is 250±20 microns and for C massecuite it is 180±10 microns.)
- d) Requirement crystal percent in final dropping massecuite. ( Generally For B massecuite the average crystal percent having 42±3% and for C massecuite having 32±3%)
- e) Sugar seed quantity in given slurry per liter. ( generally, it is having 250 to 400 grams per liter of seed slurry)
- f) Average size of sugar nuclei in sugar seed slurry. (generally, its having 3 to 5 microns)
- g) The crystal axes ratio is in the following proportion,
1.2595: 1: 0.8782
Though sugar crystal is not perfectly cubical nature, consider it as a cubical nature for simplification of calculation. So take volume of crystal = 1.2595 x 1 x 0.8782 = 1.106 (unit) 3 = 1.11 (unit) 3
Now take examples for calculation of the required quantity of seed slurry to be admitted to grain preparation in the batch pan (magma preparation)
Example 1: Grain prepared in batch pan and its material (magma) feed to continuous pan
Required Data For calculation
| S.No | Particulars | Values | UOM |
| 1 | Volume of crystal | 1.11 (unit) 3 | |
| 2 | Grain Batch pan capacity (Dropping magma) | 60 | MT |
| 3 | Continuous pan Capacity | 35 | MT/hr |
| 4 | Grain & Molasses ratio to continuous pan | 1 : 2 | |
| 5 | Grain feed Brix to Cont. pan | 88 | |
| 6 | Liquor feed brix to cont.pan | 75 | |
| 7 | Final Dropping massecuite Brix | 95 | |
| 8 | Sugar nuclei size in slurry | 5 | micron |
| 9 | Crystal size is final dropping massecuite | 220 | microns |
| 10 | Crystal percent in final dropping massecuite | 43 | % |
| 11 | Density of crystalline sucrose | 1.5879 | gm/cm3 |
| 12 | Sugar seed quantity in slurry | 380 | gm/liter |
Calculation Part:
| S.No | Particulars | Values | UOM | Remarks |
| 1 | Magma Quantity drooped in batch pan | 60 | MT | Grain pan capacity |
| 2 | Molasses required for dropped magma | 120 | MT | 60 x 3 |
| 3 | Total massecuite production | 150.3 | MT | [(60 x88) + (75 x 120)]/95 |
| 4 | Weight of the crystals in massecuite | 64.64 | MT | 150.3 x 43% |
| 5 | Volume of the single crystal in slurry | 138.75 x 10-9 | mm3 | 0.005 x 0.005 x 0.005 x 1.11 |
| 138.75 x 10-12 | cm3 | 138.75 x 10-9 / 1000 | ||
| 6 | Weight of the Single crystal in slurry | 220.32 x 10-12 | gm | 138.75 x 10-12 x 1.5879 |
| 7 | Volume of the single crystal in massecuite | 0.01181928 | mm3 | 0.220 x 0.220 x 0.220 x 1.11 |
| 1.18193 x 10-5 | cm3 | 0.01181928 / 1000 | ||
| 8 | Weight of the Single crystal in massecuite | 1.87678 x 10-5 | gm | 1.18193 x 10-5 x 1.5879 |
| 9 | Number of crystals in massecuite | 3.44397 x 1012 | 64.64 x 106/ 1.87678 x 10-5 | |
| 10 | Weight of the slurry crystals for that number of crystals in massecuite | 759 | Grams | 3.44397 x 1012 x 220.32 x 10-12 |
| 11 | Weight of the sugar in slurry per metric ton of massecuite | 5.05 | gm/ MT of massecuite | |
| 12 | Volume of the slurry required | 1.997 | Liters | 759 / 380 |
In the above calculation crystal size in seed slurry have influenced very high in slurry dosing. suppose if we take crystal size 4 microns instead of 5 microns in the above calculation, the final answer will be as follows as
| Weight of the slurry crystals for that number of crystals in massecuite | 388 | Grams | |
| Weight of the sugar in slurry per metric ton of massecuite | 2.58 | gm/ MT of massecuite | |
| Volume of the slurry required | 1.022 | Ltrs | |
So uniformity of sugar nuclei is very essential in sugar seed slurry.
Example 2 : Grain prepared in a batch pan and its material dropped as 3 pans in the same batch pan.
Required Data For calculation
| S.No | Particulars | Values | UOM |
| 1 | Grain Batch pan capacity (Dropping magma) | 60 | MT |
| 2 | Grain pan consider for massecuite dropping | 3 | pans |
| 3 | Sugar nuclei size in slurry | 5 | micron |
| 4 | Crystal percent in final dropping massecuite | 180 | microns |
| 5 | Crystal size is final dropping massecuite | 35 | % |
| 6 | Density of crystalline sucrose | 1.5879 | gm/cm3 |
Calculation Part:
| S.No | Particulars | Values | UOM | Remarks |
| 1 | Total massecuite production | 180.0 | MT | 60 x 3 |
| 2 | Weight of the crystals in massecuite | 63.00 | MT | 180 x 35% |
| 3 | Volume of the single crystal in slurry | 138.75 x 10-9 | mm3 | 0.005 x 0.005 x 0.005 x 1.11 |
| 4 | 138.75 x 10-12 | cm3 | 138.75 x 10-9 / 1000 | |
| 5 | Weight of the Single crystal in slurry | 220.32 x 10-12 | gm | 138.75 x 10-12 x 1.5879 |
| 6 | Volume of the single crystal in massecuite | 0.00647352 | mm3 | 0.180 x 0.180 x 0.180 x 1.11 |
| 7 | 6.47352x 10-6 | cm3 | 0.00647352 / 1000 | |
| 8 | Weight of the Single crystal in massecuite |
1.02793 x 10-5 | gm | 6.47352x 10-6 x x 1.5879 |
| 9 | Number of crystals in massecuite | 6.12882 x 1012 | 63 x 106/ 1.02793 x 10-5 | |
| 10 | Weight of the slurry crystals for that number of crystals in massecuite | 1350 | Grams | 220.32 x 10-12 x 6.12882 x 1012 |
| 11 | Weight of the sugar in slurry per metric ton of massecuite | 7.50 | gm/ MT of massecuite | |
| 3.553 | Ltrs | |||
Online Calculator for sugar seed slurry dosing to the pan
Note: Inputs are to be given in yellow color cells only
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