Environmental Protection from Refinery Oily Waste Water Effluents by using Coalescers
Authors: Kenawy F.A. , Kandil M.E. , Fouad M.A. , Abo-arab T.W. 
Published: December 2007

To handle ever-increasing oil water volumes and to improve water quality discharge, separation equipment should he developed to meet industry demand and match regulation. One of the consequences of the activity related to pollution prevention has been an increasing interest in research and development of oil/water separation process and equipment. However, from the economics view point, it will be necessary to focus on modifying the operation of the traditional gravity-type oil/water separation equipment in order to maximize its effectiveness which will become increasingly important as regulations become more stringent in the future. Therefore, the authors of this paper present here some efforts which had been done on this regard to improve the effectiveness of the Cross Flow Pack (CEP) separator which is normally used in the removal of oil droplets from the oily water effluents discharged from oil production facilities. The paper will outline the data obtained from an experimental work which had been done to evaluate the effect of many parameters on the effectiveness of CEP separators. These parameters are (1) shaking the plate pack of the separator, new technique, (2) influent oil characteristics such as oil droplet size and droplet distribution and (3) plate pack design such as spacing between plates, incline angle of plates.

The obtained results demonstrated that the CFP separator have the potential to recover all oil droplets greater than 30 micron when the plates are subjected to a shaking motion, inclined at 60 degree to the horizontal axis and have 0.73" spacing. Therefore, future work should focus on flow regime, hydraulic characteristics and oscillation intensity in order to demonstrate the optimum operational parameters for the CFP separator.

Introduction

As previously mentioned, the mission of this research is the study of oil-water separation in the CFP (Cross Flow Pack) separator and to evaluate the worth/feasibility of the new technique (shaking the plate pack of the CFP separator). The new technique will provide additional energy into the system to enhance the coalescence process inside the CFP separator. Consequently, the oil-water separation process could be improved and the quality of water effluent will be better. To fulfill this target, a complete thorough study had been done to simulate the operation of the CFP separator under all possible operating conditions including the new technique.

The parameters which had been considered in the research were categorized such as (1) Parameters related to shaking the plate pack of the CFP separator, (2) Parameters related to waste water characteristics (i.e. water flow rate, residence time inside the separator, oil in water concentration, oil particle size distribution and the temperature of influent stream), and (3) Parameters related to plate pack configuration such as spacing between the plates, incline angle of plates and the type of plates.

In the following sections, the experimental work which had been done to evaluate the effectiveness of the CFP separator under the previously mentioned parameters will be presented. The experimental work comprised devising a test model, a mechanism to increase the added energy to the system by shaking the plates, constructing a test loop with a heating device, providing different oily waste water streams, taking samples and making the necessary analysis.

However, as an essential requirement, it will be necessary to start with explaining the theory of operation of plate coalescers.

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