| As an effective way for petrochemical enterprises to reduce energy consumption and reduce production costs,hydraulic turbine energy recovery technology has attracted more and more scholars' attention.The technology works on the hydraulic turbine impeller through the high-pressure liquid generated in the industrial process,and converts the pressure energy of the high-pressure liquid into the mechanical energy of the turbine shaft to drive other rotating machinery or generators to achieve the purpose of energy recovery.At present,the research on hydraulic turbine technology is mainly focused on the single-stage centrifugal pump reverse turbine,and there are few studies on multi-stage hydraulic turbines.The multi-stage centrifugal pump reverse structure has broad application prospects in hydraulic turbine technology.In order to further improve its energy recovery efficiency and reduce vibration,it is necessary to analyze its flow characteristics and optimize the flow components.This paper takes the multi-stage hydraulic turbine for energy recovery in the petroleum hydrocracking process as the research object.The main research contents include:(1)The standard k-?,RNG k-?,standard k-? and SST k-? are selected respectively four turbulence models are used to numerically simulate the performance of multi-stage hydraulic turbines.The numerical calculations are compared with the external characteristic test results to obtain a turbulence model with better prediction accuracy for turbine external characteristics,and different turbulence models and The flow characteristics of the hydraulic turbine are analyzed under different flow rates;(2)The hydraulic turbine models with 120°,130° and 140° wrap angles are designed and the calculation of the steady and unsteady values is carried out to analyze the wrap angle to the turbine performance.(3)Calculate the steady and unsteady values of the hydraulic turbine models of the annular inlet chamber,the symmetrical semi-spiral inlet chamber and the spiral inlet chamber,respectively,and optimize the turbine with better hydraulic performance model.The main results are as follows:(1)The external characteristic parameters obtained by numerical simulation using the standard k-? turbulence model are more consistent with the experimental results,and the performance prediction accuracy is better;the multi-stage hydraulic turbine model is second and third.The flow distribution in the impeller is more uniform than that of the first-stage impeller.Under the rated flow and partial flow conditions,the overall internal flow of the turbine is more stable and the hydraulic loss is smaller.(2)The hydraulic turbine model with a 130° wrap angle has the best hydraulic performance.Under the same head,the 130° wrap angle hydraulic turbine model has the highest efficiency,and the 120° wrap angle turbine has the highest shaft power;at the same flow rate,the 130° wrap angle hydraulic turbine model has the head,efficiency and The shaft power is the largest;at the rated flow rate,the pressure pulsation draw value of each monitoring point in the turbine inlet chamber of the 140° wrap angle is more concentrated,and the pressure pulsation amplitude is the smallest.(3)Under the same head,the turbine model of the spiral inlet structure is about 10% more efficient than the other two models,with the largest shaft power and the smallest inlet flow,and the best hydraulic performance;symmetrical semi-spiral The turbine model of the water chamber structure has a better flow distribution on the left and bottom of the inlet chamber than the annular inlet chamber,but the overall efficiency is reduced compared to the annular structure;the turbine of the symmetric semi-spiral inlet chamber structure The pressure pulsation amplitude inside the model is the smallest of the three. |
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