ارزیابی فنی و اقتصادی استفاده از پمپ‌های دور متغیر در شستشوی معکوس فیلترهای ماسه‌ای تند (مطالعه موردی)

نوع مقاله: مقاله پژوهشی

نویسندگان

1 دانشجوی کارشناسی ارشد مهندسی عمران-آب و فاضلاب، دانشکده آب و محیط زیست، پردیس فنی و مهندسی شهید عباسپور، دانشگاه شهید بهشتی، تهران

2 استادیار گروه مهندسی عمران- آب و فاضلاب، دانشکده آب و محیط زیست، پردیس فنی و مهندسی شهید عباسپور، دانشگاه شهید بهشتی، تهران

چکیده

به‌دلیل تغییرات فیزیکی فیلتر، همچون تغییر در اندازه دانه‌های بستر، شکسته شدن نازل‌ها و تغییرات دمای آب، میزان رژیم شستشو در طول سال تغییر می‌کند. با استفاده از پمپ‌های دور متغیر می‌توان این رژیم بهینه را ثابت نگه داشت. در این تحقیق آزمایش‌ها بر روی یک فیلتر ماسه‌ای تند تک لایه در ابعاد حقیقی انجام شد و انبساط بهینه بین 7 تا 8 درصد به‌دست آمد. تحقیقات متعدد قبلی نشان داده است که برای جلوگیری از جوشش بستر، جریان آب و هوا باید به آهستگی و به تدریج تا میزان طراحی افزایش یابد؛ در تصفیه‌خانه‌های متعارف با استفاده از شیر کروی این کنترل صورت می‌گیرد که موجب تلفات انرژی و بروز فشارهای متغیر بر روی پمپ‌ها و بلوئر می‌شود. در صورتی که با استفاده از پمپ‌های دور متغیر می‌توان با حفظ فشار نسبتا ثابت به رژیم شستشوی بهینه دست یافت.پمپ‌های دور متغیر به‌دلیل تأمین کردن رژیم‌های شستشوی مختلف، این امکان را در اختیار طراحان و بهره‌برداران قرار می‌دهد تا انبساط بهینه را در بستر فیلتر به‌دست آورند. در این تحقیق میزان انبساط نتایج مثبتی همچون کاهش دوران بلوغ فیلتر، کاهش کدورت خروجی به زیرNTU  3/0 و صرفه‌جویی در مصرف آب شستشو به‌میزان 15 تا 20 درصد و در مصرف برق پمپ‌های شستشوی معکوس، به میزان 30 تا 50 درصد را به همراه داشت.

کلیدواژه‌ها

موضوعات


عنوان مقاله [English]

Technical and Economic Evaluation of the Use of Variable Speed Pumps in the Backwashing of Rapid Sand Filters (A Case Study)

نویسندگان [English]

  • sina azodi 1
  • mojtaba fazeli 2
1 MSc Student of Civil and Water & Wastewater Eng., Faculty of Water & Environment, Abbaspour College of Technology, Shahid Beheshti University, Tehran
2 Assist. Prof. of Civil and Water & Wastewater Eng., Faculty of Water & Environment, Abbaspour College of Technology-Shahid Beheshti University, Tehran
چکیده [English]

It is observed that physical changes in the filter as bed media size variation, nozzle breakage, or water temperature variations lead to changes in the backwash regime throughout the year. The remedy proposed in this article is to use variable speed pumps in order to maintain a constant and steady optimum regime. In this study, experiments were performed using a full-scale single-layer rapid sand filter to find the optimum bed expansions of 7-8%. In addition, previous research has shown that air and backwash water flows need to be slowly and gradually increased to the optimum design values in order to avoid sand boil. In a typical treatment plant, this is normally controlled by globe valves, which results in the waste of energy and variation in pump and blower pressures. Application of variable speed pumps has the advantage that a constant pressure can be maintained throughout to yield an optimum backwash regime. Variable speed pumps provide various backwash regimes which enable design engineers and water plant operators to determine the optimum expansion in sand bed filters. This range of optimum bed expansion was found to lead to such improvements as shorter filter ripening, reduced effluent turbidity to levels below 0.3 NTU, conservation of backwash water by up to 15‒20%, and savings in backwash pump power consumption by up to 30-50%.

کلیدواژه‌ها [English]

  • Rapid Sand Filter
  • Backwash
  • ripening
  • Variable speed pump
  • Optimum Expansion
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