شبیه‌سازی گام به گام هاضم بی‌هوازی لجن فاضلاب شهری با هم‌زنی نوماتیکی

نوع مقاله : مقاله پژوهشی

نویسندگان

1 دانشجوی دکتری مکانیزاسیون، گروه مهندسی بیوسیستم، دانشکده کشاورزی، دانشگاه تبریز، تبریز، آذربایجان شرقی، ایران.

2 عضو هیئت علمی گروه مهندسی بیوسیستم، دانشکده کشاورزی، دانشگاه تبریز، تبریز، آذربایجان شرقی، ایران.

3 عضو هیئت علمی گروه مهندسی مکانیک بیوسیستم، دانشکده مهندسی زراعی و عمران روستائی، دانشگاه علوم کشاورزی و منابع طبیعی خوزستان، ایران.

چکیده

هدف از این پژوهش ارائه‌ی یک استراتژی برای طراحی و شبیه‌سازی یک هاضم بی‌هوازی برای هضم لجن خام فاضلاب شهری بر اساس الگو‌های جریان درون هاضم و بررسی شرایط رسوب لجن در این هاضم بی‌هوازی بود. به این منظور، شبیه‌سازی‌ها بر اساس یک استراتژی گام به گام انجام شد. ابتدا سرعت گاز ورودی به هاضم بیوگاز تعیین شد و در مراحل بعد، به ترتیب لوله‌ی گاز بالابر و بافل آویزان مخروط ناقص شکل به طراحی هاضم اضافه شده و شبیه‌سازی‌ها انجام و مشخصات آنها تعیین شد. شبیه‌سازی برای یک هاضم استوانه‌ای در مقیاس پایلوت انجام شد. یک هاضم استوانه‌ای شفاف بر اساس نتایج بدست آمده از شبیه‌سازی‌های دینامیک سیالات محاسباتی (CFD) ساخته شد. آنالیز لجن و تعیین سرعت رسوب لجن با استفاده از فرآیند پردازش تصویر و تعیین اندازه ذارت لجن و درصد هر یک از آنها بر اساس جامدات کل (TS) لجن انجام شد. بر اساس نتایج بدست آمده تنها در ناحیه‌ی کوچکی از کف چسبیده به دیواره‌ی هاضم سرعت سیال کمتر از سرعت رسوب بزرگترین ذرات موجود در لجن ( 5- 10 ×71/4 متر بر ثانیه)  است و امکان رسوب بخش بسیار کمی از این دسته از ذرات در این ناحیه وجود داشته، که موفق بودن طراحی هاضم بر اساس شبیه‌سازی گام به گام و الگو‌های جریان برای هم‌زنی در هاضم‌های بی‌هوازی گاز بالابر را تائید کرده و نشان داد روند شبیه‌سازی گام به گام روشی مناسب بوده و می‌تواند برای شبیه‌سازی هاضم‌های بی‌هوازی بیوگاز با هم‌زنی نوماتیکی با موفقیت استفاده شود.

کلیدواژه‌ها

عنوان مقاله [English]

Step-by-step Simulation of Gas-lift Anaerobic Digester of Municipal Wastewater Sludge

نویسندگان [English]

  • davood baveli bahmaei 1
  • Yahya Ajabshirchi 2
  • Shamsollah Abdollahpour 2
  • Saman abdanan mehdizadeh 3
1 Ph.D Student of Mechanization, Department of Biosystems Engineering, Faculty of Agricultural Department, University of Tabriz, Tabriz, East Azarbaijan, Iran.
2 Faculty Member of Department of Biosystems Engineering, Faculty of Agricultural Department, University of Tabriz, Tabriz, East Azarbaijan, Iran.
3 Faculty Member of Department of Mechanics of Biosystems Engineering, Faculty of Agricultural Engineering and Rural Department, Agricultural Sciences and Natural Resources University of Khuzestan, Iran.
چکیده [English]

The purpose of this study was to present a strategy for designing and simulating an anaerobic digester for the digestion of raw municipal sewage sludge, based on the flow patterns within the digester, and to investigate the sediment deposition conditions in this anaerobic digester. For this purpose, the simulations were performed based on a step-by-step strategy. First, the inlet gas velocity to the digester was determined, then in the next steps, the draft tube and the conical hanging baffle were added to the digester design, respectively, and simulations were performed with them and determined their characteristics. Simulations were performed for a pilot-scale cylindrical digester. A transparent cylindrical digester was built based on the computational fluid dynamics (CFD) simulations results. Sludge analysis was performed, and determine the sludge sedimentation velocity using the image processing process, so the sludge particle size and each percentage of them based on the total solids (TS) of sludge was performed. According to the results, only in a small area of the floor attached to the digester wall, the velocity of the fluid is less than the sedimentation velocity of the largest particles in the sludge (4.71 × 10-5 m / s) so there was a sedimentation possibility of a small amount of these particles in this area, which confirmed the success of digester design based on step-by-step simulation and flow patterns for mixing in a gas-lift anaerobic digester and showed a step-by-step simulation strategy is suitable and can be used to simulate gas-lift anaerobic digesters successfully.

کلیدواژه‌ها [English]

  • Raw Sludge Analysis. Hanging Baffle. Image Processing
  • Computational Fluid Dynamics (CFD)
  • Draft Tube

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مهندسی بیوسیستم ایران
دوره 53، شماره 1
اردیبهشت 1401
صفحه 91-108

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سابقه مقاله

  • تاریخ دریافت: 20 مرداد 1400
  • تاریخ بازنگری: 28 آذر 1400
  • تاریخ پذیرش: 15 فروردین 1401

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