Preliminary Studies of New Water Removal Element in Purification Applications of Diesel Fuels

To effectively and efficiently remove water contamination dispersed in petrodiesel fuels, a new water removal element with both coalescence and separation features is studied in this paper. The unique droplet coalescence and separation mechanism occurring in the new water removal element is proposed. The conceptual design of this filter element is presented and the basic features of FCP filtration systems are briefly introduced. A laboratory test stand and fuel analysis procedure are described. The results from preliminary water removal tests with number 2 petrodiesel fuel demonstrate the filtration performance of the new water removal element. For example, within one single fuel flow pass through FCP filtration system equipped with the new water removal element and running at 2？GPM flow rate, the water content in 80°F, number 2 petrodiesel fuel stream can be reduced from up to 40,000？ppm upstream to 64.8？ppm or less downstream. 1. Introduction Removal of water contamination is a particularly stringent requirement for petrodiesel fuels, since the presence of even a very small amount of water in fuels can cause numerous serious problems. Issues related to fuel thermal oxidation stability, fuel filterability, fuel lubricity, promotion of soluble and insoluble gum growth, development of particulate matter, fuel filter plugging, fuel injector clogging, and fuel combustion efficiency degradation all may be related to water contamination in fuels [1–3]. The maximum water contamination level in fuels is strictly limited in worldwide fuel quality standards. For example, fuel quality standard ASTM D975 recommends a maximum water contamination level in petrodiesel fuels to be less than 500？ppm per volume (ppm: parts per million). The European standard EN590 calls that for less than 200？ppm per mass. Gravity separation, centrifugal separation, absorbent polymer separation, coalescing-based filtration, and vacuum dehydration are well-known water decontamination techniques in the quality maintenance of petrodiesel fuels. Among them, coalescing-based filtration is the most cost-effective technique for removing free and emulsified water from petrodiesel fuels at constant flow rates. It is mainly achieved by a two-stage filtration system consisting of fuel-water coalescer (FWC) at the first stage and fuel-water separator (FWS) at the second stage. That is, contaminant water dispersion in petrodiesel fuel flow is coalesced into large droplets by fibrous coalescing media of FWC, and then those enlarged droplets are deflected from fuel flow by separation mesh screen of