Study On Deacidification Technology Of High Acid Xinjiang Crude Oil

With the depletion of conventional crude oil resources,the crude oil supply appears heavy and poor trend in a world.From considering of the resource availability,economic efficiency of crude oil processing and device suitability,to develop new technology of high-acid crude oil processing is an important problem in China's oil refining enterprises.In this paper,the process of alkali extraction of acid in Xinjiang high acid mixed crude oil was researched.Based on the study of the reaction rate of NaOH and naphthenic acid,fatty acid,benzoic acid and other model compounds,phase transfer catalyst(PTC)was used to improve the reaction rate and reduced the intensity of mixing,which inhibited crude oil-(alkali)water emulsion.The results showed that the reaction rate of fatty acid and NaOH was the fastest,followed by naphthenic acid.Crude oil was similar to benzoic acid,but it was significantly lower than that of naphthenic acid.The reaction rate of phenol and NaOH was the slowest.Among PTCs,the four quaternary ammonium salts and three polyethylene glycol,dodecyl dimethyl benzyl ammonium chloride(DDBAC)can improve the reaction rate of petroleum acid-NaOH.And DDBAC can effectively inhibit the emulsification tendency of oil and water at the same time.The effects of NaOH and PTC on the stability of emulsions in the process of alkali extraction of acid in high acid mixed crude oil were investigated by using Zeta potential,oil-water interfacial tension,particle size distribution and analyser of concentrated liquid dispersions.The results show that the effect of NaOH on the stability of oil emulsion is mainly through the mechanism of double layer.DDBAC can reduce the Zeta potential of the oil-water interface and decrease the interfacial film strength,which is beneficial to the aggregation of the droplet particles,so as to inhibit the emulsification.The acid value of crude oil was reduced from 2.21 mgKOH/g to 0.41mgKOH/g,which was reached the standard of low acid crude oil,and the oil content in alkali was 3.66g/L by two stages of alkali washing and primary washing under the optimum conditions.The optimum conditions of multi stage alkali cleaning-electric deacidification process using packed column as crude oil deacidification reactor were as follows:reaction temperature 70?,NaOH concentration 3%,alkali solution/oil volume ratio 1:4.DDBAC concentration 400 mg/L.electric field strength 600V/cm.residence time 25 minute.The naphthenic acid in the alkali solution was recovered by CO2 acidification,and the acid value of the crude naphthenic acid was 142.76 mgKOH/g,however the content of fatty acid was higher.