THE EFFECT OF SEEDING ON SUCROSE CRYSTAL SIZE DISTRIBUTION AND CRISTALLIZATION KINETICS
crystal size distribution, slurry, nonsucrose, sucrose crystal growth
ABSTRACT
Abstract
INTRODUCTION
Vsl – volume of slurry (dm3)
m k – mass of product crystallizate (kg)
d sl - size of slurry particles (μm)
d k – size of product crystallizate crystals (μm)
MATERIALS AND METHODS
LG = dRRSB / dτ (3)
RG – mass growth rate (mg/(m2 . min)
m – crystal mass (mg)
A – crystal surface area (m2)
τ – time (min)
LG – linear growth rate (μm /min)
dRRSB – characteristic size (μm)
Components |
Methods |
Instruments |
|
Type |
Producer |
||
Dry substance |
Refractometric |
Refractometer DUR-S |
Schmidt&Haensch |
Sucrose |
Polarimetric |
Saccharomat |
Schmidt&Haensch |
Sucrose crystals |
Particle size distribution |
Coulter Counter, model ZM |
Coulter Electronics GmbH |
Sucrose crystals |
Microscopic |
AO Spencer |
American Optical Company |
Experiments conditions |
Experiment |
|||
A |
B |
C |
D |
|
Slurry quantity (%) |
0,07 |
0,09 |
1,7 |
2,9 |
Seeding temperature (°C) |
68 |
68 |
66 |
60 |
Final temperature (°C) |
28 |
28 |
30 |
38 |
Cooling rate (°C/min) |
0,17 |
0,17 |
0,15 |
0,10 |
RESULTS
Size range |
Mean volume (10-9 . cm3) |
Particles number (104/cm3) |
Number fractions |
Mass fractions |
Cumulative mass fractions retained |
|
d1 (µm) |
d2 (µm) |
|||||
3,09 |
3,89 |
0,02 |
47,0 |
6,6 |
0,3 |
100,0 |
3,89 |
4,90 |
0,05 |
45,0 |
6,4 |
0,5 |
99,7 |
4,90 |
6,17 |
0,09 |
67,0 |
9,5 |
1,6 |
99,2 |
6,17 |
7,78 |
0,18 |
153,0 |
21,6 |
7,5 |
97,6 |
7,78 |
9,80 |
0,37 |
171,0 |
24,2 |
16,9 |
90,1 |
9,80 |
12,35 |
0,74 |
146,0 |
20,7 |
28,7 |
73,2 |
12,35 |
15,56 |
1,48 |
56,0 |
7,9 |
22,0 |
44,5 |
15,56 |
19,60 |
2,96 |
17,0 |
2,4 |
13,4 |
22,5 |
19,60 |
24,70 |
5,92 |
4,0 |
0,6 |
6,3 |
9,1 |
24,70 |
31,11 |
11,83 |
0,7 |
0,1 |
2,2 |
2,8 |
31,11 |
39,21 |
23,67 |
0,1 |
0 |
0,6 |
0,6 |
Characteristics of model solutions |
Experiment |
|||
A |
B |
C |
D |
|
Dry substance (°Bx) |
79,30 |
79,50 |
79,20 |
79,00 |
Purity (%) |
90,30 |
90,60 |
90,50 |
90,41 |
Concentration of nonsucrose compounds (g/g H2O) |
0,37 |
0,36 |
0,36 |
0,36 |
Saturation temperature (°C) |
75 |
76 |
75 |
74 |
Supersaturation at the point of seeding |
1,10 |
1,12 |
1,13 |
1,20 |
Size range |
Crystal number (104/g) |
Number fractions |
Crystal mass (mg/g) |
Mass fractions |
Cumulative mass fractions retained |
|
d1 (µm) |
d2 (µm) |
|||||
17,19 |
22,16 |
1,549 |
17,9 |
0,1 |
0,1 |
100,0 |
22,16 |
27,93 |
0,764 |
8,9 |
0,1 |
0,1 |
99,9 |
27,93 |
35,36 |
0,296 |
3,4 |
0,1 |
0,1 |
99,8 |
35,36 |
44,56 |
0,242 |
2,8 |
0,1 |
0,1 |
99,7 |
44,56 |
56,24 |
0,354 |
4,1 |
0,4 |
0,3 |
99,6 |
56,24 |
70,86 |
0,459 |
5,3 |
1,0 |
0,8 |
99,3 |
70,86 |
89,25 |
0,632 |
7,3 |
2,8 |
2,2 |
98,5 |
89,25 |
112,50 |
0,650 |
7,5 |
5,8 |
4,7 |
96,3 |
112,50 |
141,70 |
2,213 |
25,7 |
39,2 |
31,4 |
91,6 |
141,70 |
178,50 |
1,122 |
13,0 |
39,8 |
31,9 |
60,2 |
178,50 |
224,90 |
0,206 |
2,4 |
14,6 |
11,7 |
28,3 |
224,90 |
283,40 |
0,134 |
1,6 |
19,0 |
15,2 |
16,6 |
283,40 |
357,20 |
0,006 |
0,1 |
1,7 |
1,4 |
1,4 |
Size range |
Crystal number (104/g) |
Number fractions |
Crystal mass (mg/g) |
Mass fractions |
Cumulative mass fractions retained |
|
d1 (µm) |
d2 (µm) |
|||||
17,19 |
22,16 |
0,748 |
7,5 |
0,1 |
0,1 |
100,0 |
22,16 |
27,93 |
0,247 |
2,5 |
0 |
0 |
99,9 |
27,93 |
35,36 |
0,314 |
3,2 |
0,1 |
0,1 |
99,9 |
35,36 |
44,56 |
0,511 |
5,1 |
0,3 |
0,3 |
99,8 |
44,56 |
56,24 |
0,655 |
6,6 |
0,7 |
0,8 |
99,5 |
56,24 |
70,86 |
1,047 |
10,6 |
2,3 |
2,4 |
98,7 |
70,86 |
89,25 |
2,288 |
23,0 |
10,1 |
10,7 |
96,3 |
89,25 |
112,50 |
2,103 |
21,2 |
18,7 |
19,8 |
85,6 |
112,50 |
141,70 |
1,286 |
13,0 |
22,8 |
24,1 |
65,8 |
141,70 |
178,50 |
0,488 |
4,9 |
17,3 |
18,3 |
41,7 |
178,50 |
224,90 |
0,159 |
1,6 |
11,3 |
12,0 |
23,4 |
224,90 |
283,40 |
0,762 |
0,8 |
10,8 |
11,4 |
11,4 |
Size range |
Crystal number (104/g) |
Number fractions |
Crystal mass (mg/g) |
Mass fractions |
Cumulative mass fractions retained |
|
d1 (µm) |
d2 (µm) |
|||||
11,55 |
14,56 |
0,559 |
0,9 |
0 |
0 |
100,0 |
14,56 |
18,37 |
0,916 |
1,5 |
0 |
0 |
100,0 |
18,37 |
23,12 |
1,851 |
3,0 |
0,1 |
0,1 |
100,0 |
23,12 |
29,15 |
3,102 |
5,0 |
0,5 |
0,5 |
99,9 |
29,15 |
36,74 |
6,554 |
10,7 |
2,0 |
2,0 |
99,4 |
36,74 |
46,27 |
12,429 |
20,2 |
7,7 |
7,4 |
97,4 |
46,27 |
58,29 |
15,378 |
25,0 |
12,0 |
11,6 |
90,0 |
58,29 |
73,44 |
12,690 |
20,7 |
31,4 |
30,3 |
78,4 |
73,44 |
92,53 |
6,053 |
9,9 |
30,0 |
29,0 |
48,1 |
92,53 |
116,60 |
1,683 |
2,7 |
16,7 |
16,1 |
19,1 |
116,60 |
146,90 |
0,151 |
0,2 |
3,0 |
2,9 |
3,0 |
146,90 |
185,10 |
0,003 |
0 |
0,1 |
0,1 |
0,1 |
Size range |
Crystal number (104/g) |
Number fractions |
Crystal mass (mg/g) |
Mass fractions |
Cumulative mass fractions retained |
|
d1 (µm) |
d2 (µm) |
|||||
11,55 |
14,56 |
17,940 |
13,4 |
0,3 |
0,5 |
100,0 |
14,56 |
18,37 |
19,374 |
14,5 |
0,7 |
1,2 |
99,5 |
18,37 |
23,12 |
20,079 |
15,1 |
1,5 |
2,6 |
98,3 |
23,12 |
29,15 |
20,494 |
15,3 |
3,2 |
5,6 |
95,7 |
29,15 |
36,74 |
17,998 |
13,5 |
5,6 |
9,7 |
90,1 |
36,74 |
46,27 |
17,414 |
13,0 |
10,7 |
18,6 |
80,4 |
46,27 |
58,29 |
14,167 |
10,6 |
17,5 |
30,3 |
61,8 |
58,29 |
73,44 |
4,915 |
3,7 |
12,2 |
21,1 |
31,5 |
73,44 |
92,53 |
1,126 |
0,8 |
5,6 |
9,7 |
10,4 |
92,53 |
116,60 |
0,033 |
0 |
0,3 |
0,5 |
0,7 |
116,60 |
146,90 |
0,002 |
0 |
0,0 |
0 |
0,2 |
146,90 |
185,10 |
0,002 |
0 |
0,1 |
0,2 |
0,2 |
DISCUSSION
Experiment |
A |
B |
C |
D |
Mean crystal size (µm) |
190 |
165 |
90 |
64 |
Uniformity coefficient |
4,5 |
4,3 |
4,5 |
3,5 |
Size range (µm) |
17,19–357,20 |
17,19–283,40 |
11,55-185,1 |
11,55-233,20 |
Crystal number (1/g) |
86 261 |
99 229 |
613 717 |
1 335 455 |
Maximum mass distribution |
31,9 |
24.1 |
30,3 |
30,3 |
Table 10.
Characteristics of crystal number and mass distribution
Experiment |
A |
B |
C |
D |
Crystal size < 14 μm |
33,0 |
18,3 |
41,4 |
84,8 |
Crystal size 44 – 112 μm |
24,3 |
61,4 |
58,3 |
15,2 |
Crystal size > 112 μm |
42,7 |
20,3 |
0,3 |
0 |
Experiment |
A |
B |
C |
D |
Linear growth rate (µm/min) |
1,06 |
0,92 |
0,50 |
0,36 |
Mass growth rate (mg/m2min) |
907 |
758 |
278 |
275 |
CONCLUSION
- The most favorable characteristics of crystal mass were achieved in so-lutions that were seeded with 0,07% to 1,7% w/w of slurry.
- According d3 rule, the teoretical es-timated amount of slurry was 0,15% w/w. Slurry amount of 0,09% w/w is the most similar to the teoretical va-lue.
- The amount of slurry had strong influence on the crystal size distri-bution, mean size, uniformity coeffi-cient and secondary nucleation.
- The values of crystal mass and li-near growth rate depended on the applied amounts of slurry.
- The Coulter Counter method can be applied for the determination of the crystal size distribution, crystal mass and linear growth rate.