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Article
Analysis of Galvanic Corrosion under Mass Transfer Controlled Conditions

Authors: Basim O. Hasan --- Qasim. J.M Slaiman
Journal: Journal of Engineering مجلة الهندسة ISSN: 17264073 25203339 Year: 2007 Volume: 13 Issue: 3 Pages: 1623-1636
Publisher: Baghdad University جامعة بغداد

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Abstract

Because of practical importance of protecting industrial equipments from galvanic corrosion, the need arises to analyze the effects of variables, such as temperature, velocity, and area fraction of metals on galvanic corrosion in systems under mass transfer control as in seawater (pH=7). For these reasons the galvanic corrosion of Fe-Zn is analyzed to study the influence of Reynolds number, temperature, and area fraction on the galvanic corrosion rates and galvanic corrosion potential under mass transfer control.It is found that galvanic corrosion rate of more active metal (Zn) is increased with Reynolds number while the corrosion rate of more noble metal (Fe) is slightly increased with Re depending on the galvanic potential that depends on the area fraction. Increasing Reynolds number shifts the galvanic potential to more positive values. Also increasing temperature leads to shift the corrosion potential to more negative values and to change the corrosion rate of more active metal (Zn) depending on two parameters oxygen solubility and oxygen diffusivity. As area fraction of more active metal (Zn) increased the galvanic potential is shifted to the negative anodic direction while the corrosion rate for more noble metal is decreased.

بسبب الاهمية التطبيقية لحماية المعدات الصناعية من التاكل الغلفاني ظهرت الحاجة لدراسة وتحليل تأثير بعض العوامل مثل درجة الحرارة وسرعة السائل ومساحة الكاثود والانود على التاكل الغلفاني في الانظمة التي تكون تحت سيطرة انتقال الكتلة(pH=7) كما في ماء البحر.تمت دراسة التاكل الغلفاني لمعدني الحديد والخارصين لمعرفة تاثير عدد رينولد (او السرعة) ودرجة الحرارة ونسبة المساحة في ظروف سيطرة انتقال الكتلة. أظهرت النتائج ان زيادة عدد رينولد يؤدي الى زيادة تأكل المعدن الفعال الانود (Zn ) بصورة رئيسية ويؤثر قليلا على المعدن الاقل فعالية (الكاثودFe) وحسب جهد التاكل الذي يعتمد على نسبة المساحة بين المعدنين. زيادة عدد رينولد يؤدي الى زيادة جهد التاكل الغلفاني بالاتجاه الموجب و زيادة درجة الحرارة تؤدي الى تقليل معدل التاكل الغلفاني وتقليل جهد التاكل الغلفاني(ازاحته بالاتجاه السالب) وازاحته بالاتجاه السالب اما زيادة مساحة المعدن الفعال (Zn) تؤدي الى تقليل الجهد الغلفاني وتقليل تاكل المعدن الاقل فعالية (Fe).


Article
Corrosion Inhibition of Carbon Steel under Two Phase Flow (Water-Petroleum) Simulated by Turbulently Agitated System

Authors: Hussein A. Mabmood --- Basim O. Hasan --- Qasim J. M. Slaiman
Journal: Iraqi Journal of Chemical and Petroleum Engineering المجلة العراقية للهندسة الكيمياوية وهندسة النفط ISSN: 19974884/E26180707 Year: 2007 Volume: 8 Issue: 2 Pages: 47-52
Publisher: Baghdad University جامعة بغداد

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Abstract

The corrosion of carbon steel in single phase (water with 0. IN NaCI) and two immiscible phases (kerosene-water) using turbulently agirated system is invest The experiments are carried out for Reynolds number (Re) range of 38000 to 95000 corresponding to rotational velocities from 600 to 1400 rpm using circular disk turbine agitator at 40 C. in two-phase system lest runs are carried out in aqueous phase (water) concentrations of) % vo 5 % vol., 8% vol. and 16% vol. mixed with kerosene at various Re. The effect of Reynolds number (Re), percent of dispersed phase, dispersed drops diameter, and number of drops per unit volume on the corrosion rate is investigated and discussed. Test runs are carried out using two types of inhibitors: sodium nitrite of concentrat ions 20, 40, and 60 ppm and sodium hexapolyphosphate of concentrations 485, 970, and 1940 ppm in a solution containing 8% vol. aqueous phase (water) mixed wi/h kerosene (continuous phase) at 40 °Cfor the whole range qf Re. It was found that increasing Re increases the corrosion rate and the presence of water enhances the corrosion rate by increasing the solution electrical conductivity. For two phase solution containing 8% vol. and /6% vol. of water the corrosion rate was higher than single phase (100 % vol. water). The main parameters that play the major role in determining the corrosion rate in two phase were concentration of oxygen, solution electrical conductivity, and the interfacial area between the two phases (dispersed ond continuous). Sodium nitrite and sodium hexopolyphosphate were found to be fflcient inhibitors in two phase solution for the investigated range of Re.

Keywords

corrosion --- two-phase --- kerosene --- water --- turbulent --- carbon steel.


Article
Estimation of The Optimum Bed Thickness of A Flow - Through Porous Electrode (FTPE) Working Under Mass Transfer Control

Authors: Aws Abdulmahdi Sadeq --- Sarmad Talib Najim --- Qasim J. M. Slaiman
Journal: Journal of Engineering مجلة الهندسة ISSN: 17264073 25203339 Year: 2012 Volume: 18 Issue: 4 Pages: 485-498
Publisher: Baghdad University جامعة بغداد

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Abstract

In this paper, a theoretical analysis of optimum bed thickness operates under mass transfer control for realizing a high efficiency and reaction conversion of an electrochemical reactor has been made based on flow-through porous electrode (FTPE) configuration. Many models have been used to represent the optimum bed thickness by taking a look into previous works concerned and collecting all related information, data, and models. The parameters that affect the optimum bed thickness have been visualized and reviewed, and almost all of them have been examined by experimental data from different sources and based on the various models. It has been found that the increase in electrolyte flow rate, concentration, limiting current density, and specific surface area reduce the optimum bed thickness, and the increase in electrolyte conductivity, void fraction, and overpotential range increases optimum bed thickness. The most important design parameter that has a great effect on optimum bed thickness is found to be the electrolyte flow rate for any certain operation. It has been concluded that the most appropriate two models to represent the optimum bed thickness of FTPE electrochemical reactor operating under mass transfer control based on the results are those predicted theoretically and stated by Kreysa in (1978) and Doherty et al. in (1996).

أجري في هذاالبحث تحليل نظري لاقصى سمك حشوة لمفاعل كهروكيمياوي يعمل تحت ظروف سيطرة انتقال الكتلة لتحقيق نسبة تفاعل و كفاءة عالية قد تمت على مفاعل كهروكيمياوي نوع (FTPE). نماذج عدة قد تم استخدامها لتمثيل سمك الحشوق القصوي من خلال البحث في دراسات سابقة ذات علاقة وجمع المعلومات، البيانات و النماذج. العوامل الموثرة على سمك الحشوة القصوي قد تم تجسيدها وعرضها و قد تم اختبار معظمها باستخدام بيانات عملية من مصادر عدة وتصب في نماذج مختلفة. لقد وجد ان الزيادة في جريان المحلول الالكتروليتي، تركيز المتفاعلات، limiting current density و specific surface area تقلل من سمك الحشوة القصوي، كما وان الزيادة في توصيلية المحلول، المساميه و فرق الجهد الكهربائي يزيد من سمك الحشوه الأفضل. لقد وجد ان المتغير الأكثر اهميه و ذا تأثير كبير على سمك الحشوه الأفضل هو معدل جريان المحلول لأي عمليه معينه. تأثير موقع مدخل المحلول (او موقع مكان القطب) على سمك الحشوه الأفضل تم عرضه و النتائج لم تسجل اي تاثير هام. لقد وجد ان افضل النماذج موائمة (Flow-through) تمثيل سمك الحشوه الأفضل لمفاعل كهروكيمياوي نوع يعمل تحت بتحكم انتقال الكتلة من خلال النتاتج كان نموذج Kreysa(1978) وDoherty et al. (1996).


Article
Performance of Corrosion Inhibitors Blend for Simulated Industrial Cooling Waters under Dynamic Conditions

Authors: Abeer A. Al-Khasab --- Qasim J.M.Slaiman
Journal: Iraqi Journal of Chemical and Petroleum Engineering المجلة العراقية للهندسة الكيمياوية وهندسة النفط ISSN: 19974884/E26180707 Year: 2015 Volume: 16 Issue: 1 Pages: 1-12
Publisher: Baghdad University جامعة بغداد

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Abstract

The inhibitive action of a blend of sodium nitrite/sodium hexametaphosphate (SN+SHMP) on corrosion of carbon steel in simulated cooling water systems (CWS) has been investigated by weight loss and electrochemical polarization technique. The effect of temperature, velocity, and salts concentrations on corrosion of carbon steel were studied in the absence and presence of mixed inhibiting blend. Also the effect of inhibitors blend concentrations (SN+SHMP), temperatures, and rotational velocity, i.e., Reynolds number (Re) on corrosion rate of carbon steel were investigated using Second-order Rotatable Design (Box-Wilson Design) in performing weight loss and corrosion potential approach. Electrochemical polarization measurements were used to study the behavior of carbon steel in different salts concentrations of (CWS) with pH = 7.5 in absence and presence of the inhibiting blend. The results show that the regression model (Box-Wilson Design) that has been developed using experimental data was used to verify that the interaction term of temperature with inhibitors blend and the square term of inhibitors blend are significant for corrosion rate in 0.05 N NaCl solution while the main variables are not pronounced. Also, it is found that the corrosion rate of carbon steel is increased with increasing temperature, rotational velocity, and NaCl salts concentration in uninhibited and inhibited solutions. Inhibition performance of NaNO2+ Na(PO3)6 was found to increase with its concentration up to 800 ppm inhibitors blend, and the corrosion potential is shifted to more positive direction with increasing rotational velocity, and inhibitor blend concentration.


Article
Electrochemical removal of copper from synthetic wastewater using rotating cylinder electrode

Authors: Suha A. Mohammed --- Cecilia K. Haweel --- Qasim J. M. Slaiman
Journal: Iraqi Journal of Chemical and Petroleum Engineering المجلة العراقية للهندسة الكيمياوية وهندسة النفط ISSN: 19974884/E26180707 Year: 2015 Volume: 16 Issue: 1 Pages: 13-20
Publisher: Baghdad University جامعة بغداد

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Abstract

The performance of a batch undivided electrochemical reactor with a rotating cylinder electrode of woven-wire (60 mesh size), stainless steel 316, is examined for the removal of copper from synthetic solution of o.5 M sodium chloride containing 125 ppm at pH ≈ 3.5. The effect of total applied current, rotation speed on the figures of merit of the reactor is analyzed. For an applied current of 300 mA at 100 rpm, the copper concentration decreased from 125 to <0.07 mg l-1 after 60 min of electrolysis with a specific energy consumption of 1.75 kWh kg-1 and a normalized space velocity of 1.62 h-1. The change in concentration was higher when the total applied currents were increased because of the turbulence-promoting action of the hydrogen evolution. The results suggest that the applied current must represent a compromise between the increase in space time yield or normalized space velocity and the increase in the specific energy consumption.


Article
REMOVAL of HEAVY METALS IONS from AQUEOUS SOLUTIONS USING BIOSORPTION onto BAMBOO

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Abstract

Feasibility of biosorbent of England bamboo plant origin was tested for removal of priority metal ions such as Cu and Zn from aqueous solutions in single metal state. Batch single metal state experiments were performed to determine the effect of dosage (0.5, 1 and 1.5 g), pH (3, 4, 4.5, 5 and 6), mixing speed (90, 111, 131, 156 and 170 rpm), temperature (20, 25, 30 and 35 °C) and metal ion concentration (10, 50, 70, 90 and 100 mg/L) on the ability of dried biomass to remove metal from solutions which were investigated. Dried powder of bamboo removed (for single metal state) about 74 % Cu and 69% Zn and maximum uptake of Cu and Zn was 7.39 mg/g and 6.96 mg/g respectively, from 100 mg/L of synthetic metal solution in 120 min. of contact time at pH 4.5 and 25°C with continuous stirring at 170 rpm. Experimental results have been analyzed using Langmuir and Freundlich isotherms. Both equilibrium sorption isotherms were found to represent well the measured sorption data, but Freundlich isotherm was better than Langmuir isotherm. The effect of time was studied and the rate of removal of Cu (II) and Zn (II) ions from aqueous solution by bamboo plant was found. The rates of sorption of copper and zinc were rapid initially within 5-15 minutes and reached a maximum in about 60 minutes.

Keywords


Article
Enhancement of Heat Transfer in The Tube-Sid of A Double Pipe Heat Exchanger by Wire Coils
تحسين انتقال الحرارة في أنابيب سيد من انبوب باستخدام محلزنات سلكية

Authors: Qasim J. M. Slaiman قاسم سليمان --- Abbas N. Znad عباس نوار زناد
Journal: AL-NAHRAIN JOURNAL FOR ENGINEERING SCIENCES مجلة النهرين للعلوم الهندسية ISSN: 25219154 / eISSN 25219162 Year: 2013 Volume: 16 Issue: 1 Pages: 51-57
Publisher: Al-Nahrain University جامعة النهرين

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Abstract

Heat transfer enhancement by wire coils is adopted in order to increase the thermal performance of a double pipe heat exchanger. The heat exchanger adopted is 1245 mm effective length, 28 mm outer diameter and changeable inner diameter (11 or 14 mm). Wire coils of e = 1 mm and p = 10, 20, 30 and 40 mm are used as turbulence promoters to augment heart transfer inside the inner tube at a Reynolds number range of 5000 to 40000. Water is used as the working fluid in the two sides. Variation in the experimental conditions is attained by changing the mass flowrates of unenhanced side and changing the inlet temperature of hot fluid. These conditions are followed in order to have as large amount of data points as possible in addition to observe the effect of changing these conditions. Heat transfer is increased inside the inner tube by 2.43 folds, as compared to empty tube at the same Reynolds number accompanied by friction factor increase of 4.75 folds. New correlations of Nusselt number and friction factor for the enhanced tubes are proposed as functions of Reynolds number, Prandtl number and the geometrical characteristics of inserts and tube sizes.

تم استخدام محلزنات سلكية بقطر 1 ملم وفواصل لف بمقدار 10، 20، 30 و40 ملم كمسببات شدة الاضطراب داخل الانبوب الداخلي لمبادل حراري من نوع الانابيب المتمركزة بطول 1245 ملم وبقطر خارجي 28 ملم وانبوب داخلي قابل للتغيير بقطرين 11 و 14 ملم وذلك من اجل زيادة كفائتة الحرارية في مدى رقم رينولدز بين 5000 و40000. أستخدام الماء في جانبي المبادل الحراري كما تم تنويع الظروف التجريبية وذلك بتغيير معدل الجريان الكتلي للجانب الغير المراد رفع كفائته وكذلك بتغيير درجة حرارة الدخول للمائع الساخن. الهدف من تغيير الظروف التجريبية هو الحصول على اكبر ما يمكن من النقاط التجريبية للحصول على معادلات تجريبية بأدق مايمكن بالاضافة الى معرفة مدى تأثير تغيير تلك الظروف. تم زيادة انتقال الحرارة في داخل الانبوب الداخلي بمقدار 2.43 ضعف ماهو عليه في حالة استخدام انبوب املس بنفس رقم رينولدز وكان ذلك مصحوبا بازدياد معامل الاحتكاك بمقدار 4.75 اضعاف. تم الحصول على معادلات تجريبية جديدة لرقم نسلت ومعامل الاحتكال للانبوب الداخلي للمبادل الحراري وذلك كدوال لرقمي رينولدز وبرانتل بالاضافة للابعاد الهندسية للمضافات والانابيب.

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