Coalescing Removal Of Emulsified Water From Oil

Tiny amount of emulsified water contained in fuel oil and edible oil willsignificantly reduce their quality and shelf time. Coalescing removal of emulsifiedwater has the advantages of excellent performance, low energy consumption andsmall capital investment. Until to now, unsystematic study of factors affectingcoalescence performance leads to a lack of objective standards when choosingcoalescing equipments. And there are also no published literatures about applyingcoalescence in edible oil processing. Therefore, systematic experiments were carriedout in the removal of emulsified water droplets from diesel and sesame oil.Effects of porosity, wettability, length of coalescing elements and retention timeof the emulsified water droplets on separation performance of water-in-dieselemulsion were investigated. Porosity was adjusted by compression and differentretention time could be achieved by altering flow rate and element length. In addition,effects of homogenizing conditions and initial water content were investigated. Theresults show that hydrophilic coalescing elements with low porosity exhibits betterperformance and there exists a minimal value for element length, Lmin, than which thelength of the actual element must be larger in order to achieve the best performance.Elongating coalescing elements whose length has already been larger than that of theminimal element, however, will not further improve separation performance. Theperformance is insensible to the homogenizing conditions and initial water content.Effects of porosity and coalescing media on the removal performance of waterfrom sesame oil were investigated. The results show low porosity contributes to betterseparation performance. However, separation performance of water-in-sesame oil isfar poorer than that of water-in-diesel, which could be explained by the fact thatsesame oil is mainly composed of long-chain unsaturated fatty acids, and has highviscosity and dense interfacial film.