Um reator anaeróbio tratando esgoto sintético de baixa concentração de matéria orgânica (500 mgDQO/L-1) e enriquecido com diferentes concentrações de sulfato (razões DQO/[SO4-2] de 1,34, 0,67 e 0,34) foi submetido à diferentes estratégias de alimentação (batelada e batelada alimentada de 3 h e de 6 h). O reator operou com capacidade de 4,0 L e tratou por ciclo de 8 h um volume de 2,0 L de esgoto sintético. Desta forma, executaram-se 9 condições diferentes que foram submetidas à análise com o objetivo de investigar a influência do tempo de alimentação e da razão DQO/[SO4-2] no desempenho do sistema. A temperatura do reator foi constante em 30 ± 1°C e a agitação mecânica foi fixada em 400 rpm. Como suporte para a imobilização da biomassa foram utilizados cubos de espuma de poliuretano. Os resultados obtidos demonstraram que a operação em batelada alimentada de 3 h com uma razão DQO/[SO4-2] de 0,34 apresentou as melhores condições para a remoção de matéria orgânica (89%). Quanto à remoção de sulfato observou-se uma estagnação neste mesmo modo de operação ao aumentar a concentração de sulfato no afluente, enquanto que na operação com alimentação em batelada alimentada de 6 h, a carga de sulfato removida (CSR) cresceu linearmente. Assim, a maior carga de sulfato removida foi registrada durante o ensaio em batelada alimentada de 6 h com uma razão DQO/[SO4-2] de 0,34, no qual foram removidos 0,55 g SO4-2(L.d). Com uma razão DQO/[SO4-2] de 1,34 e um tempo de enchimento de 6 h, o reator apresentou o melhor desempenho em termos de eficiência de remoção de sulfato (71%). Em todos os ensaios o reator apresentou estabilidade, com uma produção alta de alcalinidade a bicarbonato e a concentração de ácidos voláteis se manteve em níveis adequados. / An anaerobic sequencing batch reactor treating synthetic low strength wastewater (500 mgCOD/L-1) enriched with different sulfate concentrations (COD/[SO42] ratios of 1,34, 0,67 and 0,34) was operated at different fill times (batch mode and sequencing batch mode of 3 h and 6 h fill time). The reactor operated with a capacity of 4,0 L and treated per 8-h cycle 2,0 L of synthetic wastewater. Thus, 9 different configurations resulted from this configuration and were submitted under analyses with the objective to investigate the influence of each of those parameters on the performance of the system. The reactor was operated at a constant temperature of 30 ± 1°C and an mechanical agitation rate of 400 rpm. Cubic particles of polyurethane were used as support material for anaerobic biomass immobilization. The results showed that operating the reactor with a fill time of 3 h and a COD/[4-2] ratio of 0,34 was the most eficient strategy for COD removal (89%). During the same operation mode (3 h fill time) sulfate removal seemed to suffer stagnation due to the increasing sulfite concentation in the reactor, whereas with a fill time of 6 h the sulfate load removal increased linerally with increasing sulfate load. So the biggest removal, in terms of volumetric sulfate load, was obtained operating the reactor in sequencing batch mode with a fill time of 6 h and a COD/[4-2] ratio of 0,34. During this test the reactor removed 0,55 gSO4-2/(L.d) of 2,29 gSO4-2/(L.d) applied on the system. Operating at a COD/[SO4-2] ratio of 1,34 and a fill time of 6 h the reactor obtained the best results in terms of sulfate removal efficiency, with 71% of the sulfate removed from the system. In the entire period of analisis the reactor showed stability with a suficient production of alkalinity to maintain the concentration of volatil acids in adequate levels.

O presente projeto avaliou um reator anaeróbio operado em batelada e batelada alimentada seqüenciais (ASBR), em ciclos de 8 horas, utilizando biomassa granulada e agitação mecânica em um draft-tube, alimentado com água residuária sintética (500 mgDQO/L), contendo sulfato em diferentes relações DQO/[\'SO IND.4\' POT.2-\']. Em todos os ensaios o reator apresentou uma operação estável, produzindo alcalinidade e com concentração de ácidos voláteis totais em níveis adequados. Para os tempos de alimentação de 10 min, 3 h e 6 h, respectivamente, as eficiências de remoção de sulfato foram de 30, 72 e 72% nas operações nas quais o reator foi alimentado com uma relação DQO/[\'SO IND.4\'POT.2-\'] de 1,34. Nos ensaios nos quais o reator foi alimentado na relação DQO/[\'SO IND.4\'POT. 2-\'] de 0,67, as eficiências para a redução de sulfato foram de 25, 58 e 55%, respectivamente. Na operação com relação DQO/[\'SO IND.4\'POT.2-\'] de 0,34, as eficiências para redução de sulfato foram de 23, 37 e 27%, respectivamente. Desta maneira, pode-se concluir que as operações em batelada alimentada favoreceram a remoção de sulfato, enquanto foi observado que nas operações em batelada a remoção de matéria orgânica atingiu melhores eficiências. / This present work evaluate an anaerobic sequencing batch reactor (ASBR), fed in batch and fed-batch, and cycles of 8 hours, using granulated biomass and mechanical stirring in a draft-tube, fed with synthetic wastewater (500 mgCOD/L), enriched with sulfate in some COD/[\'SO IND.4\'POT.2-\'] relations. In all operations the reactor showed a stable operation, producing alkalinity and maintaining the volatile acids in adequate levels. Considering the fed periods of 10 min, 3 h and 6 h, respectively, the removal efficiencies of the sulfate was 30, 72 e 72%, in the operations when the reactor was fed with a COD/[\'SO IND.4\'POT.2-\'] relation of 1,34. In the essays when the reactor was fed in COD/[\'SO IND.4\'POT.2-\'] relation of 0,67, the efficiencies of the sulfate reduction was 25, 58 e 55%, respectively. When the reactor was operated with COD/[\'SO IND.4\'POT.2-\'] relation of 0,34, the efficiencies of sulfate reduction 23, 37 e 27%, respectively. Thus, is possible to conclude that the operations in fed-batch increased the efficiency of sulfate removal, at what time was observed that in batch operations the organic matter removal attained improved efficiencies.

Um reator anaeróbio tratando esgoto sintético de baixa concentração de matéria orgânica (500 mgDQO/L-1) e enriquecido com diferentes concentrações de sulfato (razões DQO/[SO4-2] de 1,34, 0,67 e 0,34) foi submetido à diferentes estratégias de alimentação (batelada e batelada alimentada de 3 h e de 6 h). O reator operou com capacidade de 4,0 L e tratou por ciclo de 8 h um volume de 2,0 L de esgoto sintético. Desta forma, executaram-se 9 condições diferentes que foram submetidas à análise com o objetivo de investigar a influência do tempo de alimentação e da razão DQO/[SO4-2] no desempenho do sistema. A temperatura do reator foi constante em 30 ± 1°C e a agitação mecânica foi fixada em 400 rpm. Como suporte para a imobilização da biomassa foram utilizados cubos de espuma de poliuretano. Os resultados obtidos demonstraram que a operação em batelada alimentada de 3 h com uma razão DQO/[SO4-2] de 0,34 apresentou as melhores condições para a remoção de matéria orgânica (89%). Quanto à remoção de sulfato observou-se uma estagnação neste mesmo modo de operação ao aumentar a concentração de sulfato no afluente, enquanto que na operação com alimentação em batelada alimentada de 6 h, a carga de sulfato removida (CSR) cresceu linearmente. Assim, a maior carga de sulfato removida foi registrada durante o ensaio em batelada alimentada de 6 h com uma razão DQO/[SO4-2] de 0,34, no qual foram removidos 0,55 g SO4-2(L.d). Com uma razão DQO/[SO4-2] de 1,34 e um tempo de enchimento de 6 h, o reator apresentou o melhor desempenho em termos de eficiência de remoção de sulfato (71%). Em todos os ensaios o reator apresentou estabilidade, com uma produção alta de alcalinidade a bicarbonato e a concentração de ácidos voláteis se manteve em níveis adequados. / An anaerobic sequencing batch reactor treating synthetic low strength wastewater (500 mgCOD/L-1) enriched with different sulfate concentrations (COD/[SO42] ratios of 1,34, 0,67 and 0,34) was operated at different fill times (batch mode and sequencing batch mode of 3 h and 6 h fill time). The reactor operated with a capacity of 4,0 L and treated per 8-h cycle 2,0 L of synthetic wastewater. Thus, 9 different configurations resulted from this configuration and were submitted under analyses with the objective to investigate the influence of each of those parameters on the performance of the system. The reactor was operated at a constant temperature of 30 ± 1°C and an mechanical agitation rate of 400 rpm. Cubic particles of polyurethane were used as support material for anaerobic biomass immobilization. The results showed that operating the reactor with a fill time of 3 h and a COD/[4-2] ratio of 0,34 was the most eficient strategy for COD removal (89%). During the same operation mode (3 h fill time) sulfate removal seemed to suffer stagnation due to the increasing sulfite concentation in the reactor, whereas with a fill time of 6 h the sulfate load removal increased linerally with increasing sulfate load. So the biggest removal, in terms of volumetric sulfate load, was obtained operating the reactor in sequencing batch mode with a fill time of 6 h and a COD/[4-2] ratio of 0,34. During this test the reactor removed 0,55 gSO4-2/(L.d) of 2,29 gSO4-2/(L.d) applied on the system. Operating at a COD/[SO4-2] ratio of 1,34 and a fill time of 6 h the reactor obtained the best results in terms of sulfate removal efficiency, with 71% of the sulfate removed from the system. In the entire period of analisis the reactor showed stability with a suficient production of alkalinity to maintain the concentration of volatil acids in adequate levels.

O presente projeto avaliou um reator anaeróbio operado em batelada e batelada alimentada seqüenciais (ASBR), em ciclos de 8 horas, utilizando biomassa granulada e agitação mecânica em um draft-tube, alimentado com água residuária sintética (500 mgDQO/L), contendo sulfato em diferentes relações DQO/[\'SO IND.4\' POT.2-\']. Em todos os ensaios o reator apresentou uma operação estável, produzindo alcalinidade e com concentração de ácidos voláteis totais em níveis adequados. Para os tempos de alimentação de 10 min, 3 h e 6 h, respectivamente, as eficiências de remoção de sulfato foram de 30, 72 e 72% nas operações nas quais o reator foi alimentado com uma relação DQO/[\'SO IND.4\'POT.2-\'] de 1,34. Nos ensaios nos quais o reator foi alimentado na relação DQO/[\'SO IND.4\'POT. 2-\'] de 0,67, as eficiências para a redução de sulfato foram de 25, 58 e 55%, respectivamente. Na operação com relação DQO/[\'SO IND.4\'POT.2-\'] de 0,34, as eficiências para redução de sulfato foram de 23, 37 e 27%, respectivamente. Desta maneira, pode-se concluir que as operações em batelada alimentada favoreceram a remoção de sulfato, enquanto foi observado que nas operações em batelada a remoção de matéria orgânica atingiu melhores eficiências. / This present work evaluate an anaerobic sequencing batch reactor (ASBR), fed in batch and fed-batch, and cycles of 8 hours, using granulated biomass and mechanical stirring in a draft-tube, fed with synthetic wastewater (500 mgCOD/L), enriched with sulfate in some COD/[\'SO IND.4\'POT.2-\'] relations. In all operations the reactor showed a stable operation, producing alkalinity and maintaining the volatile acids in adequate levels. Considering the fed periods of 10 min, 3 h and 6 h, respectively, the removal efficiencies of the sulfate was 30, 72 e 72%, in the operations when the reactor was fed with a COD/[\'SO IND.4\'POT.2-\'] relation of 1,34. In the essays when the reactor was fed in COD/[\'SO IND.4\'POT.2-\'] relation of 0,67, the efficiencies of the sulfate reduction was 25, 58 e 55%, respectively. When the reactor was operated with COD/[\'SO IND.4\'POT.2-\'] relation of 0,34, the efficiencies of sulfate reduction 23, 37 e 27%, respectively. Thus, is possible to conclude that the operations in fed-batch increased the efficiency of sulfate removal, at what time was observed that in batch operations the organic matter removal attained improved efficiencies.

The late University of Canterbury civil engineering lecturer Peter Giddens developed a range of simple microhydro turbines, with publications from as early as the 1980s. He considered that a range of simple but well-designed turbines which covered the gamut of possible small sites would be more useful than any single turbine. He started with radial inflow turbines, then set about extending their range of applicability by increasing specific speed. That extension was continued by the research in this thesis, which aimed to produce a design with a minimum efficiency of 70 % at a specific speed of at least 600 (rev/min, kW, m). Achieving those targets would differentiate it from existing microhydro designs. In order to reach those performance targets, the volute, runner, and draft tube were examined through experiment and computational fluid dynamics models to characterize past designs and test the validity of their embodied assumptions. A prototype with a design specific speed of 650 was built and fully characterized by dynamometer testing. Measurements of the outlet velocity distribution of two of Peter Giddens’s volutes confirmed that single tangential inlet volutes are not torque-free when certain geometric conditions are met; swirl increased through those volutes by 70 % or more depending on the design. A new overall turbine design was proposed, where axial flow enters the runner and swirling flows leaves it. This required the design of a novel volute. Through computational analysis, the effect of swirling flow entering the conical draft tube was shown to affect its pressure recovery: negatively for draft tubes with small angles, positively for larger angles. It was shown that the peak pressure recovery of an optimum draft tube was not likely to be improved upon by the use of swirl, and since there was uncertainty in the analysis, a conservative draft tube was specified for the prototype. A flat-bladed runner was designed for the prototype and computational modeling indicated its performance would be sensitive to small changes in flow angle. Despite that sensitivity — an intrinsic property of high specific speed runner velocity triangles — the computational model was shown to give good predictions of the runner flow characteristics, although not its effciency. Finally, a 1.2 kW prototype was built and achieved a peak net effciency of 64 % as defined by the American Society of Mechanical Engineers at a net head of 2.07 m, a flowrate of 94 L/s, and a runner shaft speed of 1670 rev/min, corresponding to a specific speed of 740. Maximum measured runner efficiency of 87 % also occurred at those conditions. Compared to existing designs, that performance extended the operational envelope of microhydro turbines considerably. A three-zone computational model of the entire prototype was assembled and trialled, but not validated. It is concluded that for efficient high specific speed turbines, volute swirl characteristics must be known with confidence, as the volute sets the conditions at the leading edge for peak runner efficiency. A simple but efficient runner may be made using flat blades, showing the potential for this geometry even when made by limited workshops. Adding a free-vortex tangential velocity distribution to the inlet flow of a stalled conical draft tube may increase its pressure recovery, although it is not likely to exceed the best performance obtainable with axial inlet flow. Therefore taking measures to reduce the peak fluid velocity entering the draft tube could be more beneficial to overall performance than seeking outright improvements in draft tube pressure recovery.

This report contains an investigation of fluid injection techniques used in the purpose of reducing deleterious flow effects occurring in the draft tube of Francis turbines when operating outside nominal load. There is a focus on implement ability at Jämtkrafts hydroelectric power plants and two power plants were investigated, located in series with each other named Lövhöjden and Ålviken. The only profitable scenario found with some degree of certainty was an increase in the operating range upwards to allow overload operation. Findings show that both air and water can be introduced in various locations to improve hydraulic efficiency around the turbine parts as well as reduce pressure pulsations in harmful operating regions. Investments in such systems have proven useful and profitable at several facilities with poorly adapted operating conditions. But due to losses in efficiency when operating injection systems, it turns out unprofitable in situations where it does not improve the operating range in a way that is resulting in increased annual or peak production.

Diploma thesis deals with design and exploration of installation in the draft tube of the swirl turbine. Use of the draft tube is defined in the first part, with illustration of energetical gain and efficiency of draft tube. Further the suitable shape of draft tube is studied by CFD computing. Design, research and evaluation of installation in the draft tube are solved in the main part.

The aim of this master’s thesis is the optimal design of swirl turbines for small water power plant. It is described a different possibilities of turbine‘s install for locality Vrchlabí. It presents a design of turbines and draft tubes. For the installation of turbines is computed theoretical production of annual electric energy. Furthermore it describes a design of supply channel and intake structure.

Hydraulic energy is one of the most important sources in the world for electricity production. Nowadays the trend is to limit the production of the electricity from fossil fuels and to protect the environment. The main idea is to use more renewable energy sources such as wind and solar energy. Unfortunately, these alternative sources are strongly dependent on current weather conditions, which causes the instability of the electrical grid. Luckily pumped storage and hydraulic power plants provide the solution. However, it requires an extension of the operating range of the hydraulic machines. For that reason, the water turbines now operate over and extended range of regimes, that can be quite far from the best efficiency point. Hence two types of unstable two-phase flows in the Francis turbine draft tube occur: part load overload. This diploma’s thesis is focused on the Francis turbine operating at the part load. During part load conditions the helical vortex rope is being developed in the draft tube, it causes pressure pulsation and it can lead to the hydro-acoustic resonance, which damages the elements of the power plant. The aim is to eliminate the pulsation by jet control of the swirling flow in the draft tube. In the diploma’s thesis, various approaches to jet control of the flow in conical diffuser are tested using the computational fluid dynamics.

This diploma thesis describes design of a new shape of the draft tube for small hydro Katovice with maintaining built dimension. First part of this thesis is devoted to the formulation of the problem, description of basic function of the draft tube, its efficiency and other formulas. In the second part of this thesis the analysis is made for original design supported by CFD calculation. Furthermore a new design of the draft tube is made with comparison of original draft tube.