Experimental Research On Droplet Deposition And Liquid Film Thickness In Supersonic Swirling Separator

Supersonic swirling separation technology has unique advantages in the field of natural gas dehydration,and has a huge industrial demand background,but there are few reports on the experimental research on liquid phase separation in this process.In order to reveal the law of liquid phase separation in supersonic swirling separator and enrich detection methods,the experimental research on droplet deposition and liquid film flow in supersonic swirling separator are carried out.The main research results are as follows:1.A method for predicting droplet deposition based on Support Vector Regression was proposed.Acoustic emission sensors were used to obtain the acoustic emission signals under different droplet deposition.It was found that the frequency changes caused by droplet deposition is mainly below 80 k Hz.Then,the normalized energy features were obtained by discrete wavelet decomposition(DWT)and empirical mode decomposition(EMD).The principal component analysis(PCA)was utilized to extract comprehensive features and achieve data dimensionality reduction,and finally set up machine learning training and testing data sets to cross-validate the model prediction performance.The results showed that the root mean square error(RMSE)of the prediction model is 0.88 L/h,and the mean absolute percentage error(MAPE)is10.99%,which can achieve a relatively accurate prediction of droplet deposition.2.A flexible liquid film measurement system based on FPGA was designed.Firstly,the electrode structure and excitation mode were optimized by finite element analysis software,and the FPC flexible liquid film sensor was fabricated.Then,according to the idea of plane liquid film equivalent calibration,a set of static plane liquid film calibration device was designed and the electrode excitation and signal acquisition system was developed with FPGA.Finally,a high-precision plane liquid film calibration experiment was carried out.The results showed that the liquid film measurement system has better sensitivity from 50 μm to 500 μm,and the fitting error of the sensor output characteristics is within ±5%,which as the experimental research basis for supersonic swirling separator liquid film measurement.3.Experiments on the liquid film thickness of the wet gas outlet of the separator under different inlet liquid contents and back pressure ratios were carried out.The changing laws of the liquid film were analyzed by statistical analysis methods,continuous wavelet transform(CWT)and wavelet packet decomposition(WDP).The results showed that with the increase of the inlet liquid content,the liquid film flow can be divided into three types: droplet random flow,filamentary spiral flow and annular mist flow.The thickness of the base layer liquid film on the wetted wall was about 70μm.The intermittent flow made the liquid film thickness distribution show bimodal characteristics.And the liquid film fluctuation frequency was mainly concentrated in20 Hz ～ 80 Hz.The proportion of energy in the low frequency domain,bounded by 24 Hz to 28 Hz,continued to decreased,while the high frequency domain increased.As the back pressure ratio increases,the liquid film thickness increasesed first and then decreased.Shock wave would seriously affect the formation of the liquid film.