Hydrodynamics of two phase flow for coalescing and non coalescing systems

مقدم أطروحة جامعية

Abd Allah, Hibah Mahmud

الجامعة

الجامعة التكنولوجية

الكلية

-

القسم الأكاديمي

قسم الهندسة الكيمياوية

دولة الجامعة

العراق

الدرجة العلمية

ماجستير

تاريخ الدرجة العلمية

2008

الملخص الإنجليزي

Two-phase flow systems are widely used in various industrial processes.

Bubble columns are two-phase gas-liquid systems in which gas is dispersed through a distributor and bubbles rise through a liquid in vertical cylindrical columns.

Bubble columns arc widely used in chemical, petrochemical and biological industries.

Knowledge about hydrodynamics of bubble columns is necessary for design purposes, In this study, the hydrodynamics in a gas-liquid bubble column was experimentally investigated.

The effects of superficial gas velocity, liquid phase properties and gas distribution on gas holdup, bubble characteristics and drag coefficient were studied. The experimental work was carried out using QVP glass column of 0.1 m inside diameter and 2m height.

Two types of gas distributors were used.

The first type was porous ceramic distributor of 240 pm mean pore size, the second type was perforated plate made of Perspex of 4mm thickness and with 88 drilled holes of 0.5mm hole diameter. Various liquids covering a sufficiently bioad range of viscosity and surface tension values were employed which are : Distilled water, Glycerine having concentrations ; 10%, 30%, 50% and 70% were used to simulate the behavior of coalescing viscous liquids and Butanol having concentrations: 0.6% and 1,5% to simulate the behavior of non-coalescing organic liquids.

Air was used as the gas phase with superficial gas velocity range from 0.0063 to 0,0339 m/s spanning the homogeneous flow regime.

For all sets of experiments the height of liquid phase was maintained constant at 0.1 m from the gas distributor, The hydrodynamic parameters such as, gas holdup, bubble size, bubble size distribution and bubble rise velocity were studied with aid of: 1.

Computerized conductivity probe system (CCPS). 2.

High speed digital camera. The experimental data obtained showed that the gas holdup increases and the bubble size slightly increases with increasing superficial gas velocity.

The bubble rise velocity, however, was found to decrease with increasing superficial gas velocity.

It was observed that with an increase in liquid phase viscosity, a decrease in gas holdup and an increase in bubble size was obtained while it was observed that with an increase in weight percent of alcohol, an increase in gas holdup and a decrease in bubble size were obtained. A statistical analysis was performed to get a general correlation for the gas holdup (ƸG) as a function of the parameters studied. ƸG = 0.048703 Fr 0.530755 Ga 0.133047 Bo0.253508 (DO / DC)-0.070889 Where the correlation coefficient (R) was equal to (0.97471) and the average absolute relative error was (7.S %). The effect of gas holdup, liquid viscosity and weight percent of alcohol on drag coefficient was studied.

It was observed that the drag coefficient increases with increasing gas holdup, liquid viscosity and weight percent of alcohol. An empirical correlation is performed for the drag coefficient as a function of the parameters studied as follows: CD = 1.826129 ƸG 0.067566 RE-0.033534 FRB-0.864212 Where the correlation coefficient (R) was equal to (0.98734) and the average absolute relative error was (23 %).

التخصصات الرئيسية

الكيمياء

الموضوعات

• ديناميكا الموائع
• الديناميكا
• الفقاعات الهوائية

• APA
• MLA
• AMA

لغة النص

الإنجليزية

نوع البيانات

رسائل جامعية

رقم السجل

BIM-305592