Study On Cavitation Suppression Characteristics Of Coal Liquefaction Regulating Valve Based On Bionics

Under the background of the major strategic needs of carbon neutrality and carbon peak,coal liquefaction,coal gasification and coal chemical industry are used as key engineering technologies for clean coal conversion to help achieve efficient utilization of coal energy.The coal liquefaction regulating valve is an indispensable key equipment in the coal liquefaction system.It is widely used in process pipelines such as gasification and slag water treatment.It runs in an environment with high pressure difference and high flow rate for a long time,causing damage to the valve core and valve seat structure.The service life of the regulating valve is greatly reduced,which seriously affects the reliability and economy of the coal chemical system.Therefore,it is of great significance to study the cavitation damage mechanism of coal liquefaction regulating valve,carry out bionic optimization design of regulating valve body structure,and improve the anti-cavitation performance of valve body to ensure the design and stable operation of key equipment in large coal chemical industry.Firstly,based on the fluid dynamics model and turbulence model,the numerical model of coal liquefaction regulating valve is established,and the visual experimental platform of the internal flow field of the regulating valve is built.The high-speed camera is used to collect the image of the cavitation area of the throttle orifice of the regulating valve,and the variation characteristics of the gas-liquid two-phase flow field in the regulating valve are explored.Secondly,based on the principle of Bio-TRIZ bionics,the bionic structure of cuttlefish nozzle is mapped to the valve seat,and a new type of regulating valve seat structure with bionic characteristics is designed.The similarity of the valve seat structure with bionic drainage hole is evaluated from three aspects: structure,function and boundary condition.Then,it is verified by numerical simulation that the bionic valve seat can reduce the intensity of cavitation.Finally,the pressure flow characteristics of the bionic valve seat structure are studied experimentally.It is pointed out that with the increase of the relative opening under the same pressure difference,the bionic drainage hole structure has little effect on the pressure flow characteristics of the coal liquefaction regulating valve.The flow field regulating characteristics of the regulating valve with bionic valve seat are studied.According to the variation characteristics of vortex dynamics and special vortex system,the cavitation suppression behavior of the bionic valve seat on the flow field is revealed.Firstly,the distribution of pressure field,velocity field and cavitation field in the regulating valve with bionic valve seat is explored,and the influence mechanism of bionic drainage hole structure on the distribution of threedimensional cavitation morphology is revealed.Secondly,the experimental study on the periodic variation of cavitation and cavitation collapse of the regulating valve with bionic valve seat is carried out,and the influence of bionic drainage hole structure on the collapse of cavitation group in the flow field is analyzed.Finally,based on the Ωidentification method,the cavitation suppression mechanism of the valve seat with bionic drainage hole is revealed,which provides a useful reference for improving the service life of the coal liquefaction regulating valve.The structural parameter optimization of the regulating valve of the bionic valve seat is studied.Firstly,the spatial angle and size of the bionic drainage hole structure are taken as the design variables,and the cavitation intensity of the valve core head is taken as the optimization target.The orthogonal test is designed to determine the influence weight of multiple design variables.Secondly,based on the NSGA-II genetic optimization algorithm in ISIGHT,the multi-parameter optimization of the regulating valve is carried out to determine the structural parameters with the best anti-cavitation performance.Finally,the cavitation suppression efficiency and other indicators are proposed to quantify the cavitation suppression efficiency of the regulating valve with bionic seat structure.It is pointed out that the inhibition efficiency of the bionic drainage hole is about 30% to 50%,which verifies the effectiveness of the bionic drainage valve seat structure on the cavitation inhibition of the flow field of the regulating valve.There are 59 figures,13 tables,and 91 references in this thesis.