بررسی مؤلفه‌های عملیاتی مؤثر بر اختلاط واکنشی اسید- باز درون مخزن همزن‌دار به‌روش لیزری PIV/PLIF

نوع مقاله : مقاله پژوهشی

نویسندگان

دانشگاه صنعتی سهند

چکیده

در این تحقیق اختلاط واکنشی خنثی­سازی اسید- باز با واکنش اسیداستیک و آمونیوم هیدروکسید درون مخزن همزن­دار برای مطالعۀ رفتار متقابل اختلاط و واکنش شیمیایی با استفادۀ همزمان از روش‌های لیزری القای صفحه­ای نور شارندگی (PLIF)1 و سرعت‌سنجی تصویری ذرات(PIV)2بررسی شده‌است. همچنین مواردی همچون سرعت چرخش پره، فاصلۀ پره از کف مخزن، وجود بافل و خواص روانه‌شناختی سیال درون مخزن که با تغییر و بهینه­سازی آنها می­توان شرایط حاکم بر عملکرد مخازن اختلاط را بهبود بخشید زمینۀ این بررسی بوده‌است. نتایج به­دست آمده نشانداد که پیشرفت واکنش خنثی­سازی اسید- باز در شرایط بررسی شده، تحت کنترل
شرایط اختلاط واکنش­دهنده­ها بوده‌است. برای بررسی اثر فاصلۀ پره از کف مخزن، نسبت‌های 25/0
C/T= ، 5/0C/T= و 75/0C/T= انتخاب شدند که C فاصلۀ پره از کف مخزن و T قطر مخزن است. همچنین این آزمایش‌ها در سه‌سرعت پرهrpm 100،
150rpm
 و 200rpm تکرار شدند. نتایج نشانداد که با افزایش فاصلۀ پره از کف مخزن که معادل افزایش نسبت C/T است، زمان واکنش به‌طور چشمگیری کاهش می‌یابد. علاوه‌بر این، در نسبت‌های ثابت C/T، با افزایش سرعت چرخش پره، زمان واکنش به‌شدت کاهش می‌یابد. همچنین بهمنظور بررسی اثر تعداد بافل‌های درون مخزن، از یک‌مخزن بدون بافل، 2 بافل و 4 بافل درسرعت‌های 150rpm،100rpm و 200rpm استفاده شد. بر اساس نتایج مشخص شد که با افزایش تعداد بافل درون مخزن، زمان واکنش
کاهش می­یابد. یکی دیگر از مؤلفه‌های مورد بررسی در این تحقیق، گرانروی سیال بود که آزمایش‌ها در گرانروی‌های
 35 µ=35mPa.s ،  µ=55mPa.s  و µ=75mPa.s انجام شدند. نتایج حاصل از این آزمایش‌ها نشانداد که با افزایش گرانروی سیال از  µ=35mPa.s،
به  µ=55mPa.s
، زمان واکنش افزایش چشمگیری مییابد؛ اما افزایش گرانروی سیال به مقدار µ=75mPa.s تأثیر کمتری بر میزان افزایش زمان واکنش دارد.

کلیدواژه‌ها


عنوان مقاله [English]

Investigating the Operational Parameters Affecting the Acid-Base Reaction Inside the Stirred Tank by PIV/PLIF Technique

نویسندگان [English]

  • M. H. Ahmadi
  • J. S. Moghaddas
  • E. Ataee
Sahand University of Technology
چکیده [English]

In this study, the acid-base neutralization reaction of acetic acid and ammonium hydroxide reaction inside a mixing tank to study the mixing interaction and chemical reaction by using simultaneous planar laser-induced fluorescence (PLIF)[1] and particle image velocimetry (PIV)[2] methods has been examined. The blade rotation speed, the blade distance from the bottom of the tank, the presence of buffers and the rheological properties of the fluid inside the tank are all the parameters that can be changed and optimized to improve the conditions of performance of mixed tanks which they are investigated to test them effects. The results showed that the progress of the acid-base neutralization reaction in the studied conditions was under the control of the mixing conditions of the reactants. To investigate the effect of blade distance from the tank floor, the ratios
C/T = 0.25, C/T = 0.5 and C/T = 0.75 were selected which C is the distance of the blade from the tank floor and T is the diameter of the tank. Also the experiments were repeated at three speeds of 100 rpm, 150rpm and 200rpm. The results showed that by increasing the distance of the blade from the bottom of the tank, which is equivalent to increasing the
C/T ratio, the reaction time was significantly reduced. In addition, at constant C/T ratios, the reaction time decreases sharply by increasing blade rotation speed. Also, in order to investigate the effect of the number of buffles in the tank, a buffleless,
2 buffles and 4 buffles blades were used at speeds of 100 rpm, 150rpm and 200rpm. Based on the results, it was found that as the number of buffles in the tank increased, the reaction time decreased. Also, a comparison of experiments performed in each tanks with three different speeds showed that the time-reduction ratios in tanks with fixed number of buffles at different speeds have a similar downward trend. Another parameter studied in this study was fluid viscosity, which was tested in
µ= 35 mPa.s, µ=55 mPa.s, µ=75 mPa.s. The results of these experiments showed that with increasing fluid viscosity from µ=35 mPa.s to µ=55 mPa.s, the reaction time increased significantly, However, increasing the fluid viscosity by µ=75 mPa.s has less effect on the reaction time.



[1]. Planar Laser-Induced Fluorescence


[2]. Particle Image Velocimetry

کلیدواژه‌ها [English]

  • Stirred tank
  • Acid-Base Reaction
  • Planar Laser-Induced Fluorescence
  • Particle image velocimetry
  • Curved-Blade Turbine
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