Investigation of continuous stirred tank reactors for improving the mixing in anaerobic digestion: A numerical study
In this paper, mechanical impeller mixing has been analyzed through CFD which has proven to be a useful method for simulating mixing before manufacturing the digester. In this work, simulations were done for five different digester designs for TS level of 12.1%. While the fifth digester was cylindri...
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| Format: | Article |
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Elsevier
2023-09-01
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| Series: | Results in Engineering |
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| Online Access: | http://www.sciencedirect.com/science/article/pii/S2590123023004449 |
| _version_ | 1797682460309323776 |
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| author | Hemant Thakur Narendra Kumar Verma Atul Dhar Satvasheel Powar |
| author_facet | Hemant Thakur Narendra Kumar Verma Atul Dhar Satvasheel Powar |
| author_sort | Hemant Thakur |
| collection | DOAJ |
| description | In this paper, mechanical impeller mixing has been analyzed through CFD which has proven to be a useful method for simulating mixing before manufacturing the digester. In this work, simulations were done for five different digester designs for TS level of 12.1%. While the fifth digester was cylindrical, the other four were cubical in design with varying impeller diameters and the number of impellers. The power law model was used to resemble the sewage sludge as a non-Newtonian fluid. The modified versions of dead volume and uniformity index were used along with velocity gradient and mixing energy level to quantify the quality of mixing. An analysis of the temperature distributions during mixing and heating was done using a thermal study. The operating speed of 250 rpm was finalized after testing at continuously increasing speeds from 50 to 600 rpm for a flat blade type impeller. As per the thermal model, a 250-W heater raised the temperature by around 15 °C in just 10 min. It was found that cylindrical vessels worked better than cubical digesters and larger impellers also helped in improving the mixing. The cylindrical digester which achieved about 67% homogeneity at a mixing energy level of around 0.95 W/m3, was the optimum design among the investigated digesters. |
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| format | Article |
| id | doaj.art-58f0cdee3751467a8cbfccac359b2d4d |
| institution | Directory Open Access Journal |
| issn | 2590-1230 |
| language | English |
| last_indexed | 2024-03-12T00:00:02Z |
| publishDate | 2023-09-01 |
| publisher | Elsevier |
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| series | Results in Engineering |
| spelling | doaj.art-58f0cdee3751467a8cbfccac359b2d4d2023-09-18T04:30:44ZengElsevierResults in Engineering2590-12302023-09-0119101317Investigation of continuous stirred tank reactors for improving the mixing in anaerobic digestion: A numerical studyHemant Thakur0Narendra Kumar Verma1Atul Dhar2Satvasheel Powar3School of Mechanical and Materials Engineering, Indian Institute of Technology Mandi, Himachal Pradesh , 175005, IndiaSchool of Mechanical and Materials Engineering, Indian Institute of Technology Mandi, Himachal Pradesh , 175005, IndiaSchool of Mechanical and Materials Engineering, Indian Institute of Technology Mandi, Himachal Pradesh , 175005, India; Corresponding author.School of Mechanical and Materials Engineering, Indian Institute of Technology Mandi, Himachal Pradesh , 175005, India; School of Technology and Business Studies, Energy Technology, Högskolan Dalarna, Falun, 79188, Sweden; Corresponding author.School of Mechanical and Materials Engineering, Indian Institute of Technology Mandi, Himachal Pradesh, 175005, India.In this paper, mechanical impeller mixing has been analyzed through CFD which has proven to be a useful method for simulating mixing before manufacturing the digester. In this work, simulations were done for five different digester designs for TS level of 12.1%. While the fifth digester was cylindrical, the other four were cubical in design with varying impeller diameters and the number of impellers. The power law model was used to resemble the sewage sludge as a non-Newtonian fluid. The modified versions of dead volume and uniformity index were used along with velocity gradient and mixing energy level to quantify the quality of mixing. An analysis of the temperature distributions during mixing and heating was done using a thermal study. The operating speed of 250 rpm was finalized after testing at continuously increasing speeds from 50 to 600 rpm for a flat blade type impeller. As per the thermal model, a 250-W heater raised the temperature by around 15 °C in just 10 min. It was found that cylindrical vessels worked better than cubical digesters and larger impellers also helped in improving the mixing. The cylindrical digester which achieved about 67% homogeneity at a mixing energy level of around 0.95 W/m3, was the optimum design among the investigated digesters.http://www.sciencedirect.com/science/article/pii/S2590123023004449Sewage sludgeComputational fluid dynamicsAnaerobic digesterMechanical mixingStirred reactor |
| spellingShingle | Hemant Thakur Narendra Kumar Verma Atul Dhar Satvasheel Powar Investigation of continuous stirred tank reactors for improving the mixing in anaerobic digestion: A numerical study Results in Engineering Sewage sludge Computational fluid dynamics Anaerobic digester Mechanical mixing Stirred reactor |
| title | Investigation of continuous stirred tank reactors for improving the mixing in anaerobic digestion: A numerical study |
| title_full | Investigation of continuous stirred tank reactors for improving the mixing in anaerobic digestion: A numerical study |
| title_fullStr | Investigation of continuous stirred tank reactors for improving the mixing in anaerobic digestion: A numerical study |
| title_full_unstemmed | Investigation of continuous stirred tank reactors for improving the mixing in anaerobic digestion: A numerical study |
| title_short | Investigation of continuous stirred tank reactors for improving the mixing in anaerobic digestion: A numerical study |
| title_sort | investigation of continuous stirred tank reactors for improving the mixing in anaerobic digestion a numerical study |
| topic | Sewage sludge Computational fluid dynamics Anaerobic digester Mechanical mixing Stirred reactor |
| url | http://www.sciencedirect.com/science/article/pii/S2590123023004449 |
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