Study On Preparation And Properties Of Composite Filter Media For Fuel/water Separation

With the popularization of low sulfur diesel and high pressure common rail system,the particle size of the water droplets in diesel is reduced and the stability is increased due to the increase of surfactant content and pump pressure in diesel.As a result,the performance of the existing filter media for fuel/water separation is decreased rapidly.This paper is mainly aimed at solving the problem of the performance evaluation of fuel/water separation and fiber dispersion and effect of the structure of the composite filter media on fuel/water separation efficiency,which provides reference for the development of new oil separation materials,and has important practical application significance.In this thesis,the fuel/water separation test bench for the filter media is designed according to SAE J1488 and ISO16332.The test method of fuel/water separation performance of the filter media was developed.The problem of the general fuel/water separation test bench was solved because the flow was too high to be used for filter media testing.The test bench can not only test fuel/water separation efficiency and pressure drop but also observe the coalescence of water droplets on the upper and lower reaches of the filter media in real time.In the process of developing the filter media,in order to solve the problem of fiber dispersion observation and evaluation,a special fiber dispersion evaluation device is designed,which can be widely used in the evaluation of the dispersibility of all kinds of short fibers.That is of great significance for the application of new fibers and the development of special paper.In this paper,Singlelayer and Double-layer composite materials for fuel/water separation were developed,and their structure and properties were analyzed.Hydrophobic fiber can reduce the effect of surfactant on wettability of fiber surface and the hydrophilic fiber with small diameter can reduce the pore size of the filter and increase the coalescence efficiency of the filter material.Thus,the single and double layer composite filter media for fuel/water separation is prepared by the hydrophobic kapok fiber,double melting point PET fibers and the hydrophilic fine glass fibers.The effects of hydrophobic fiber content,double-layer structure,multistage filtration and fuel/water interfacial tension on the separation performance are studied in this paper.The results show that with the increase of the fiber content in the inflow layer,the fuel/water separation efficiency of single-layer filter media and double-layer filter media was increased firstly,then decreased and then increased.The fuel/water separation efficiency of double-layer filter miedia was higher than that of single-layer filter media in the same condition as the content of kapok fiber in the inflow layer.And the fuel/water separation efficiency of the double-layer composite filter media with 20% kapok fiber content was peak of 89.5%.The fuel/water separation efficiency increased to 92.9% after the separation layer filter material was added to the downstream of the former filter media.Under the same fuel/water interfacial Tension(17~21mn/m),the fuel/water separation efficiency of the double-layer composite filter media with 20% kapok fiber content increased by more than 17.8% compared to commercial filter media's.