Experimental study of clogging in bottom racks. Case of circular bars with high void ratios

Resumen

Bottom intake systems have been used in mountain regions countries to produce renewable energy and reduce maintenance costs. Sediment laden flows may reduce the efficiency of bottom intake racks due to the obstruction of the spacing between the bars. This leads to serious operational problems and important increases in maintenance costs. Most of the recommendations are based on the experience obtained during the operation phase and sometimes after a stop in the production of energy. The Hidr@m Group of the Universidad Politécnica de Cartagena with financial support from the Seneca Foundation of the Region of Murcia has been working in the study of bottom intake systems and presented experimental results with gravel-sized sediments in bottom racks made with T-shaped flat bars. A main objective is to characterize the most efficient design parameters, such as: bar profile, spacing between bars, and longitudinal slope. The current work includes a campaign of racks with circular bars and void ratio of 0.60. Flow rates vary between 0.155 to 0.250 m 3 /s/m. 100 kg of gravels with d50 ≈ 58 mm are tested in each case. Longitudinal slopes are also variable in the range of 10 to 35% and tests are developed in an existing device. Main results include the analysis of derivation capacity of the bottom rack with circular bars and a high void ratio. Comparison with the previous works as well as the approach of new tests are presented.