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العنوان
Liquid Solid Mass Transfer In Agitated Vessels\
المؤلف
El-Naqeara, Hamdy Mohamed Mahmoud.
هيئة الاعداد
باحث / حمدى محمد محمود محمد النقيرة
hamdiy-elnageara@hotmail.com
مشرف / يحيي عبد القادر الطويل
مشرف / محمد حلمي عبد العزيز موسي
مناقش / احمد امين زعطوط
مناقش / الفت عبد الشافي فضلي
الموضوع
Chemical Engineering.
تاريخ النشر
2012.
عدد الصفحات
139 p. :
اللغة
الإنجليزية
الدرجة
ماجستير
التخصص
الهندسة الكيميائية
تاريخ الإجازة
1/12/2011
مكان الإجازة
جامعة الاسكندريه - كلية الهندسة - الهندسة الكيميائية
الفهرس
Only 14 pages are availabe for public view

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Abstract

The liquid-solid mass transfer behavior of a new stirred tank reactor consisting of vertical copper cylinders distributed at the wall of the reactor, this wall was a copper sheet whose back was isolated by epoxy resin. The diffusion controlled dissolution of copper in acidified dichromate technique was used, in the present study variables studied were:
l. lmpeller rotation speed. 2. lmpeller geometry:
J. Four blade flat turbine.
11. Four blade 45° pitched turbine
3. Cylinder diameter.(d)
4. Radial distance between the vertical cylinders.(S)
5. Physical properties of the solution (p, ~ and D).
6. Effect of drag reducing polymers (polyox WSR-301).
The study has revealed the following results:
I. The mass transfer coefficient increases with increasing impeJler rotation speed.
2. Cylinder diameter has a little effect on the mass transfer coefficient.
3. The mass transfer coefficient increases with increasing radial distance between the vertical cylinders.
4. Radial flow impeJler (four blade flat turbine) was found to produce higher rate of mass transfer than the axial flow impeJler (four blade 45° pitched turbine).
5. The data were correlated using the method of dimensional analysis. The following correlations were obtained:
(
5)0.27
I. Radial flow impeJler: Sh = 0.223 Reo.69 SC033 d
For the conditions: 1075 < Sc < 1506; 1838 < Re < 16672; 2.95 < ~ < 11.78.
(
5)0.25
H. Axial flow impeJler: Sh = 0.295 Reo 64 SCO.33 d
For the conditions: 1075 < Sc < 1506; 1838 < Re < 16672; 2.95 < ~ < 11.78.
6. The presence of vertical cylinder turbulence promoters increases the volumetric mass transfer coefficient by an amount ranging from 12.5% to 214.5% in case of radial flow impeJler and from 8.7% to 79.7% in case of axial flow impeller depending on the operating conditions compared to that at the wall without turbulence promoters.
7. The presence of Poly ox WSR-301 drag reducing polymer decreases the rate of mass transfer by an amount ranging from 3.5-32 % depending on polymer concentration and impeJler rotation speed.
ii
8. The present suggested reactor can fmed applications in processes such as:
J. Catalytic organic synthesis.
lI. Catalytic waste water treatment to remove organic pollutants by wet oxidation.
111. Catalyzed biochemical reactions using immobilized enzyme to produce pharmaceuticals, food stuff, and to remove organic pollutants from waste water.
iv. Photo catalytic reactions on a semiconducting catalyst such as Ti02, ZnS
and CdS. Photo catalytic reactions use DV light to conduct reactions such as oxidation, reduction, isomerization, polymerization, and waste water treatment
v. Diffusion controlled electrochemical reaction such as removal of heavy metals from waste solution by cathodic deposition or removal of refractory organic pollutants by anodic oxidation.
vi. Removal of heavy metals from waste water solutions by cementation on
less noble metal.
The reactor offers the advantages that the vertical tubes distributed around the vessel wall not only act as active turbulence promoters which enhance the rate of diffusion controlled reactions taking place at the tank wall but also they can act as a heat exchanger to control the solution temperature at the optimum value by passing either cold water or steam in case of exothermic reactions or endothermic reactions respectively. Besides, the vertical tubes lining the inner wall of the agitated vessel act as baffles which convert the ineffective swirl (tangential) flow to the more effective axial and radial flow which improve the mixing efficiency of the agitated vessel.