Alexandra Cheng's Individual Contribution Page
Stock Tank Mixing and Pipeline Cooling Team
Spring 2014 Contributions
Team Stock Tank Mixing goals this semester will focus focused on re-designing the stock tank pump mixing system to achieve optimal efficiency and energy input usage.
Two main designs were fabricated and tested on the small scale: a shallow bucket with small holes in the bottom and a plate (each attached to a handle) that were pumped up and down in the stock tank. The bucket design was meant to physically bring dense solution located at the bottom of the tank to the top of the tank while the plate design created turbulence and jets to encourage mixing. Both designs achieved full mixing with the same number of pump cycles, but the plate design requires less time because when the plate reaches the surface height, it is immediately plunged back down to the bottom of the tank. The bucket design, meanwhile, requires waiting for the fluid to drain out before being plunged back to the bottom. Full-scale designs will be based on the plate mixer.
goal density efficiently. A plate mixer and water injection system were developed and were found to be highly effective in properly making and mixing stock solutions.
Pipeline Cooling goals included analyzing the heat transferred to influent water via raw water pipelines and researching possible solutions. Cool roof coating solutions were found to be effective but all products researched were very expensive. Further research is required to understand the impact of water temperature changes on sedimentation tank performance before investing capital in cool roof coating solutions. It is possible that redesign of the plate settlers will be required to rectify the impact of warm influent water circulation in the sedimentation tankAnother design tested to decrease required input injected water into the bottom of the dense solution in the stock tank. Initial tests showed water injection was incredibly effective in mixing the majority of the stock solution, and any additional required mixing was achieved by the plate mixer.
Fall 2013 Contributions
Team goals this semester included purchasing non-lab environment appropriate (e.g. not easily breakable) hydrometers or other suitable measurement tools for PACl and chlorine stock solutions, testing and confirming the PACl concentration-density relationship, and designing and fabricating a centrifugal pump to be used in the stock tank to ensure complete mixing of stock solutions.
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