Research And Implementation Of Key Technologies For Low Temperature Fluidity Testing Of Oil Products

The low temperature fluidity of oil determines whether the oil can be used normally and transferred smoothly at low temperature.It is an important test index in oil pipeline transportation,fuel supply,oil refining and other fields.At present,the detection of low-temperature fluidity of oil products in China is mostly manual,with low detection accuracy and slow testing speed.Therefore,the research of automatic testing technology and related instruments for low temperature fluidity of oil products is particularly important.Firstly,the mechanism of low-temperature crystallization of oil products and various low-temperature fluidity testing methods were analyzed.A composite low-temperature fluidity testing method was proposed,and the overall scheme of the testing system was designed.The high-precision low-temperature field generation,sample photoelectric sensing identification and low-temperature environment anti-interference technology were studied in depth.In the low temperature field generation technology,the multi-stage semiconductor refrigeration technology based on Stirling refrigerator heat dissipation was used to achieve the limit control temperature as low as – 113?.In view of the non-linear characteristics of semiconductor refrigeration temperature control,the anti-saturation integral PID algorithm and the single neuron PID algorithm based on particle swarm optimization were used to control the constant temperature and speed respectively,and the accurate temperature control was realized.In the field of photoelectric sensor identification,a photoelectric sensor unit was designed with SSPA sensor as the core.Two-point correction method and median filter method were selected to reduce the photoelectric information noise,and adaptive exposure algorithm was used to ensure the multi-sample adaptability of photoelectric detection threshold.On this basis,the photoelectric information analysis method was studied.The crystalline state and solidification state of oil products were accurately distinguished by the difference of light intensity change and the cumulative value of light intensity relative change,respectively.In the low temperature anti-jamming technology,it was easy to dew in the ambient air of the test room at low temperature,which affects the low temperature fluidity test.An air circulation system based on molecular sieve gas adsorption method and piston pump was designed.Variable pressure gas pulse was generated by switching control of solenoid valve.Drying dew suppression and pulse gas purging were realized in the test room.Finally,the performance tests of low temperature temperature control,photoelectric sensor and gas generation are carried out through experiments,and multi-sample comparison tests are carried out with imported instruments.The experimental results show that the performance of the cryogenic fluidity testing system designed in this paper meets the design expectation and can effectively test the cryogenic fluidity of oil products.