Study On Kinetic Of Ethylene Hydrate Formation And Separation Of Methane-ethylene In Water/oil Emulsion

The way that separating low-carbon olefin from FCC dry gas by hydrate formation had advantages of low cost and mild operating condition comparing to the traditional cryogenic distillation.The experimental data and kinetic research on the hydrate formation in the water/oil emulsion was meaningful.In this paper,the kinetic data of ethylene hydrate in the water/oil emulsion on different conditions was determined,and the separation experiment between methane and ethylene was conducted.The main contents and results were shown as following:(1)The ethylene hydrate formation kinetics in water/oil emulsion was systematically measured in isochoric reactor.The effects of reaction temperature(271.15K-276.15K),initial pressure(2.50MPa-3.50MPa),water cut(10%-40%),stirring rate(400rpm-1000rpm),emulsion amount(90mL-120 m L)and Span 80 concentration(2%-8%)on formation kinetics were conducted.The result showed that hydrate formation rate increased with lower temperature,higher stirring rate,higher Span 80 concentration and larger emulsion amount.The suitable operation condition was with 273.35 K,3.0MPa,800 rpm,2% Span 80,30% water cut and 100 m L emulsion.(2)The Kolmogorov-Johnson-Mehl-Avrami(KJMA)kinetic equation based on crystallization theory was used to describe the ethylene hydration process in the w/o emulsion.There was some deviation between experimental and simulative result at the late stage of reaction,the model was modified by taking consideration of the decay of contact area of gas-liquid phase.The simulation result of KJMA modified model was in good accordance with experimental result,the kinetic parameter and Avrami were determined by regressing the experimental data.(3)The separation experiment between methane and ethylene was conducted by the hydration in the water/oil emulsion.The effects of reaction temperature,initial pressure,water cut,emulsion amount,stirring rate and Span 80 concentration on the separation result was studied in the experiment.The result showed that the ethylene concentration in the mixed gas decreased from 34% to 9.97%,and the recovery of ethylene achieved 90.36% with 273.35 K,5.0MPa,30% water cut,800 rpm,2% Span 80,which had a good separation result.The experimental result also showed that the water/oil emulsion was recyclable.