SUGAR SEED SLURRY REQUIREMENT CALCULATION

 

Sugar Seed Slurry Requirement Calculation for B and C massecuite

Sugar Seed Slurry in pan boiling of Crystallization

The sugar crystallization(pan boiling) is one of the important section in sugar industry.  In crystallization process follows different techniques to form sugar crystals nuclei (grain techniques). Generally true seeding method is one of the best method of graining in pan boiling scheme. In this method sugar seed slurry used for crystal formation.

In true seeding method, the liquor is concentrate upto it will reaches  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 having mixer of  organic solvent and very finely ground sugar particles.( 3 to 5micron size sugar nuclei).

The basic requirements of organic solvents to be used for sugar seed slurry preparation are as follow

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 using in preparing the seed slurry.  Usually the seed slurry prepared in precipitation method and ball milling of refined sugar in alcohol for a period of time.

The magma or seed used as a footing into the batch pan or continuous pans. The size and quality of the magma have placed a significant role on final crystal size and exhaustion of the massecuite. The uniform size of crystal with correct estimated quantity of  sugar seed slurry  dosing is very essential to get good quality of magma.

Now the estimation of sugar seed slurry to the pan depended upon following parameters.

a) Generally Grain prepared in batch pan and its magma feed to 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 having 250±20 microns and for C massecute having 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 massecute having 32±3%)

e) Sugar seed quantity in given slurry per liter. ( generally its 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 required quantity of seed slurry to admitted to grain preparation in 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 in 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 micron instead of 5 microns in the above calculation, the final answer will be come as follow 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 batch pan and its material dropped as 3 pans in 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 in 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