A master chemical engineer student has designed a pilot plant for the production
ID: 702981 • Letter: A
Question
A master chemical engineer student has designed a pilot plant for the production of sugar. It is a continuous crystallization vessel containing 130 liters of sucrose slurry fed with 65 liters/hr of supersaturated solution. The withdrawal rate of product slurry is also 65 liters/hr. A nucleation rate B of 9.72 x 107nuclei/liters hr, and growth rate G of 0.035 mm/hr are expected. Calculate the anticipated crystal size distribution of the slurry on different standard screens.
Mesh number
Screen size (mm)
20
0.85
25
0.71
35
0.5
50
0.3
100
0.15
120
0.125
Mesh number
Screen size (mm)
20
0.85
25
0.71
35
0.5
50
0.3
100
0.15
120
0.125
Explanation / Answer
The number of crystals N between I1 and I2 crystal size, Ni=BV/Q*(exp(-I1Q/(GV))-exp(-I2Q/(GV)))
Nuclear rate, B = 9.72*10^7 nucleir/l/hr
Vessel volume,V = 130 litre
Q, supersaturation solution flowrate = 65 l/hr
G, growth rate = .035 mm/year
mi, crystal fraction at ith mesh = Ni/?Nj
Mesh Number,i I1 I2 Ni mi 120 .125 .15 9769468 .3 100 .15 .3 20089743 .61 50 .3 .5 2516819 .07 35 .5 .71 145720 .004 25 .71 .85 6601 .0002 20 .85 Infinity 1033 3.1*10^-5 ?Nj 32529386Related Questions
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