Research On Real-time Measurement Method Of High Temperature Molten Salt Flow

With the gradual escalation of environmental issues such as air pollution,people are increasingly aware of the importance of protecting the natural environment,and the demand for clean energy continues to rise.Solar thermal power generation is an essential component of the renewable clean energy field.Solar energy has significant advantages such as abundant resources,safety,and renewability,making it an ideal renewable clean energy source.High-temperature molten salt is a low-cost,efficient,and thermally stable heat storage medium in solar thermal power plants.Compared to traditional heat storage media,high-temperature molten salt has numerous advantages,and it is widely used as a heat storage and transfer medium in many solar thermal power plants.However,the strong high-temperature corrosiveness,wide viscosity range with temperature variations,and high operating temperatures of molten salt pose significant challenges to the applicability of flow meters and other instruments in the molten salt system.The subject takes high-temperature molten salt flow detection as the application background and utilizes a binary nitrate mixture consisting of 60%sodium nitrate and 40%potassium nitrate as the fluid medium.It proposes an ultrasonic flow measurement method based on a precession vortex flowmeter.By connecting a probe to the high-temperature pipeline and the ultrasonic sensor,the ultrasonic sensor is able to operate within a suitable ambient temperature range.The structure of the precession vortex flowmeter induces periodic vortex precession of the fluid within the pipeline.The ultrasonic signal is modulated by the phenomenon of vortex precession.Using an ultrasonic transducer to detect the modulated acoustic signal,the frequency of the vortex precession can be obtained,thereby obtaining the fluid flow rate:(1)The important significance of molten salt flow measurement is analyzed,the characteristics and physical parameters of molten salt are introduced in detail,and the principle introduction and feasibility analysis of existing flow measurement methods at home and abroad are carried out.The principle of flow measurement method based on ultrasonic wave and waveguide technology is introduced.(2)An ultrasonic precession vortex flowmeter is proposed,and the steady-state thermal simulation of the waveguide is carried out.It is concluded that a probe with a size of 1x15x200mm can make the ultrasonic transducer work within the working temperature range.The coupling method of waveguide and pipe and ultrasonic transducer and the coupling fixtures are selected and designed.(3)Based on the DN150 precession vortex flowmeter,the ultrasonic precession vortex flowmeter is modeled and designed.The finite element simulation software was used to simulate and analyze the flow field of its fluid domain,and the vortex precession frequency was obtained by analyzing the signal curve received by the ultrasonic receiving transducer.(4)By comparing the vortex precession frequency detected by the piezoelectric measurement method and the ultrasonic measurement method under different inlet flow rates,the measurement error of the two measurement methods is obtained,which proves the effectiveness of the ultrasonic precession vortex flowmeter.