Hydynamic characteristics of three-phase npn-newtonina

مقدم أطروحة جامعية

Jawad, Ali Husayn

مشرف أطروحة جامعية

Muhammad, Thamir J.
Sulayman, Abbas H.

الجامعة

الجامعة التكنولوجية

الكلية

-

القسم الأكاديمي

قسم الهندسة الكيمياوية

دولة الجامعة

العراق

الدرجة العلمية

دكتوراه

تاريخ الدرجة العلمية

2006

الملخص الإنجليزي

In recent years, bubble columns with highly viscous liquids are found in widespread applications in chemical and biotechnological processes especially in biochemical reactors and pollution treatment.

The aim of this work is to study the hydrodynamic characteristics in three-phase fluidized beds.

The following phenomena were studied e.g.

gas- holdup, bubble rise velocity, mean bubble diameter, bubble frequency, minimum fluidization velocity, superficial gas velocity and the physical and rheological properties of liquid phase.

The experimental work of gas-liquid-solid fluidized beds system was carried out using QVF glass column 0.106m internal diameter and 2 m height to study the motion of multi-bubble.

A perforated Teflon plate was used as gas distributor, with 53 holes, 7 Mir» in diameter and free surface area of 23.11 %.Four of Carboxyl Methyl Cellulose concentrations of 0.1 %, 0.5 %, 1 %, and 2 %, were used as non-Newtonian (pseudo plastic) liquids.

On the other hand Glycerin concentrations having 50 % and 75 Vo were used as Newtonian liquids.

Air, 02 and C02 were used as the gas phase with superficial velocity 0.03 -1.4 m / s.

Two different types and sizes of particles were used in the present work : The first was activated carbon with diameter 0.25mm -0.75mm and density 770 Kg / m3 and the second was Ni-Mo/Al203 with diameter 1.8 mm and density 2500 Kg / m3.

The above conditions of this work were studied the effect of it on the hydrodynamics parameters such as, total gas holdup, local gas holdup, bubble rise velocity, and bubble diameter were studied with the aid of : 1- Direct visual and optical observations : which were based on visualization.

2- Photographs and video films analysis, using two computerized digital cameras.

Computerized Conductivity Probe System (CCPS) : in which the probe detects the difference in conductivity of gas -liquid-solid of the three-phase system.

The graphical relations between the gas-holdup, bubble rise velocity and mean bubble diameter, superficial gas velocity were studied, and compared well with the theoretical models.

The minimum liquid fluidization velocity in three-phase fluidized beds with non-Newtonian fluids is 0.014 m / s for activated carbon and 0.017 m / s for Ni-Mo/Al203 at 0.1 % CMC.

Also it was found that the gas-holdup, bubble rise velocity and mean bubble diameter increase with increasing superficial gas velocity.

To study the effect of hydrodynamic interaction in three fluidized beds on the gas-holdup, bubble rise velocity, mean bubble diameter and superficial gas velocity, three-dimensional figures were presented.

Three-dimensional plots were given.

Ubr = fi (Sg, Usg) b = f (8g, Usg) Gas hold-up was correlated with the superficial gas velocity and liquid and solid properties.

The correlation obtained gave an average absolute error and correlation coefficient of 1.42 % and 0.0071, respectively.

The following mathematical model was derived to estimate the bubble rise velocity in three phase system using momentum equation for each phase (dp = 0.5-1.8 mm and Ws = 1.278-2.314 Kg).

The results of comparison between the mathematical model with present work and empirical correlations presented by other investigator show that the average absolute error is equal to 23 % and 27 %, respectively.

التخصصات الرئيسية

الكيمياء

الموضوعات

• ديناميكا الموائع

• APA
• MLA
• AMA

لغة النص

الإنجليزية

نوع البيانات

رسائل جامعية

رقم السجل

BIM-305644