• Title/Summary/Keyword: pump diffusion mixer

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Evaluation of Coagulants Dispersion in Pump Diffusion Mixer for Water Treatment (CFD모사 기법을 이용한 Pump Diffusion Mixer내의 응집체 확산분포에 대한 평가)

  • Park, Young-Oh;Park, No-Suk;Kim, Seong-Su;Kim, Ki-Don;Lim, Kyung-Ho
    • Journal of Korean Society of Water and Wastewater
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    • v.22 no.1
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    • pp.49-63
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    • 2008
  • The objectives of this research were to evaluate the pressurized/the main inlet water flowrate ratio which have been used as the most important parameter for operating the pump diffusion mixer until now, to suggest the alternative operating parameter and the relating criteria if the flowrate ratio was not inadequate. For the objectives of this research, computational fluid dynamics (CFD) simulation was conducted for 21 cases of flowrate ratio in full-scaled pump diffusion mixer. From the results of CFD simulation, the local velocity gradient values were calculated in each case in order to analyze the simulation results in more detail. For verifying CFD simulation, wet test was conducted. The wet test was to measure the factual coagulant dispersion distribution at a distance of 5.4m from deflector. From both results of CFD simulation and wet test, flowrate ratio was inadequate as operating parameter or criteria, on the other hand the pressurized/the main inlet velocity ratio(dimensionless) was useful in predicting the performance of pump diffusion mixer. Also, the injected coagulant could be dispersed evenly in overall cross section on the condition that pressurized/the main inlet velocity ratio(dimensionless) is over at least 20.

Evaluation of Flow Characteristics within In-Line Mixer for Water Treatment using CFD Technique (CFD모사 기법을 이용한 관내 혼화장치내 흐름 특성 평가)

  • Park, Dae-Jin;Park, Young-Oh;Park, No-Suk;Kim, Seong-Su;Wang, Chang-Kuen
    • Journal of Korean Society of Water and Wastewater
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    • v.22 no.3
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    • pp.351-358
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    • 2008
  • The modified in-line mixer which was suggested in this study for small water treatment facilities was evaluated on the performance of coagulation. For the objectives of this research, computational fluid dynamics(CFD) simulation was applied for analysis of flow characteristics within the modified in-line mixer. For verifying the results of CFD simulation, wet tests for the pilot plant were conducted. The wet test was to measure the actual coagulant dispersion distribution on the overall cross-section at a distance of 5.5D from the chemical injection point. From the results of CFD simulation and wet test, it was shown that the coagulant dispersion within the modified in-line mixer was occurred more uniformly than within the existing PDM(Pump diffusion Mixer). The results have confirmed the modified in-line mixer had several advantages compared with the existing PDM in terms of dispersion efficiency.

Characteristics of Coagulants Distribution by the Pumping Rate in Pump Diffusion Mixer (Pump Diffusion Mixer에서 압력수량에 따른 응집제 확산분포 특성)

  • Park, Youngoh;Kim, Ki-Don;Park, No-Suk;Lim, Jae-Lim;Lim, Kyung-Ho
    • Journal of Korean Society of Water and Wastewater
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    • v.22 no.1
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    • pp.65-71
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    • 2008
  • This study collected the latest 30-year (1976~2005) continuous rainfall data hourly recorded at 61 meterological observatories in Korea, and the continuous rainfall data was divided into individual rainfall events. In addition, distribution charts of average rainfall event-depth were created to facilitate the application to the overflow risk-based design of detention storage basin. This study shows that 4 hour is appropriate for SST (storm separation time) to separate individual rainfall events from the continuous rainfall data, and the one-parameter exponential distribution is suitable for the frequency distribution of rainfall event depths for the domestic rainfall data. The analysis of the domestic rainfall data using SST of 4 hour showed that the individual rainfall event was 1380 to 2031 times, the average rainfall event-depth was 19.1 to 32.4mm, and ranged between 0.877 and 0.926. Distribution charts of average rainfall event-depth were created for 4hour and 6 hour of SST, respectively. The inland Gyeongsangbuk-do, Western coastal area and inland of Jeollabuk-do had relatively lower average rainfall event-depth, whereas Southern coastal area, such as Namhae, Yeosu, and Jeju-do had relatively higher average rainfall event-depth.

MIXING PROCESS FLOW ANALYSIS OF PDM AND HYDRAULIC MIXING BASIN SYSTEM USING CFD (CFD를 이용한 펌프확산 및 수리낙차 방식의 혼화공정 흐름 분석)

  • Lee, S.W.;Chang, S.M.;Cho, Y.
    • Journal of computational fluids engineering
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    • v.22 no.1
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    • pp.1-7
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    • 2017
  • The mixing of water and chemicals is an important process in the water purification plant. In this paper, we compare PDM(pump diffusion mixer) and hydraulic mixer at the basin in the mixing process. The proper flow rates are predicted and compared in both mixers using CFD technique. As a result, the flow rate of purifier chemical liquid should be 5% of that of water for the optimal performance of mixing process. The characteristics of the two mixing methods are compared with each other for strong and weak points on the operation of the purification system, discussed in the view point of CFD simulations.

Evaluation of Pressurized Water Mixing of Big Pipe with CFD at Water Treatment Process (CFD를 활용한 수처리공정 대형관에서 압력수 혼합공정 평가)

  • Cho, Young-Man;Yu, Hyun-chul;Jang, Gyeong-Hyuk;Jung, Yong-Jun
    • Journal of Korean Society on Water Environment
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    • v.37 no.3
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    • pp.168-174
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    • 2021
  • Mixing is a very important unit in water treatment process. A mechanical stirring method is generally used for mixing, but recently, the use of pressurized water mixing method (pump diffusion flash mixer) has gained interest because it is more advantageous in terms of mixing time, noise, energy consumption, and maintenance. The following conclusions were obtained from the study of pressurized water mixing method by Computational Fluid Dynamics. Firstly, the mixing degree in the pipe increased as the density of water increased. Secondly, even if the relative velocity between flow rate in the pipe and the pressurized water was constant, the mixing degree decreased as the flow velocity in the pipe increased. Thirdly, the stronger the injection energy the higher the mixing degree. It was also found that the mixing degree was greatly affected by the injection velocity as compared to the injection flow amount. Finally, the required energy to achieve 95% mixing degree at the distance of 10 times diameter in big pipes of 500 mm to 3000 mm was 0.3 to 4.5 kJ. The result of this study could be used in the process design of injection with water purification chemicals, such as, ozone, chlorine, and coagulant.