EFFECT OF BAFFLES ON OIL WATER SEPARATOR

1 INT J curr SCI 2013 , 7: E 146-152 research article ISSN 2250-1770 EFFECT of BAFFLES on oil WATER SEPARATOR Agunwamba JC*, Ukomadu Kingsley and Oguguo Chinelo Department of Civil Engineering, University of Nigeria Nsukka, Nigeria *Corresponding author: Abstract The EFFECT of number of BAFFLES and their loaders on oil removal efficiency was investigated is laboratory gravity oil SEPARATOR . Performance tests were conducted to determine the oil removal efficiencies of the oil separators with varying baffle location and number under different discharges. The removal efficiency (E) of the SEPARATOR who found to be inversely proportional to internet flow rate, effluent concentration and directly proportional to the retention tune (t). Three different oils were used at different influent concentration, for engine oil, Coil = 15300 mg/L, for groundnut oil, Coil = 13000 mg/L, for hydraulics oil, coil = 35700 mg/L, The SEPARATOR with the highest no of baffle at a discharge of gave the highest removal efficiency, also the SEPARATOR with the baffle location at 2/3 from the inlet at discharge of produced the highest efficiency.

2 Keywords: BAFFLES , free oils, oil- WATER separation removal efficiencies Received: 09th June; Revised: 16thJune; Accepted: 26thJune; IJCS New Liberty Group 2013 Introduction In the refineries, chemical plants, electric power plants and many other industrial facilities the separation of various oil and WATER mixtures can cause problems. These problems are often the result of imperfect understanding of the nature of the mixtures and how to take advantage of their properties to accomplish the required separations (Mohr, 1995). Gravity separation is one of the widely used unit operations for removal of and G from wastewaters. The performance of a gravity oil- WATER SEPARATOR is dependent on the rising velocity of the individual oil droplets and system surface flow rate. This study is a view of oil WATER separation and EFFECT of BAFFLES on oil WATER SEPARATOR , thereby ascertaining its removal efficiencies in relation to the influent and effluent concentration, flow rates and retention time.

3 Material and Methods SEPARATOR development In this research 5 different channels separation technique with varied number of BAFFLES was proposed to enable wastewater landed with free oil to flow into the channel system and allow the horizontal velocity of flow (Vh) to decelerate with distance from the inlet. The reduction in horizontal velocity of flow Vh would enhance high efficiency of oil removal. This reduction in horizontal velocity of flow due to the presence of different BAFFLES promotes optimum oil-liquid separation. However, the fluid elements flows more easily in reduced number of BAFFLES and escapes quicker from the oil droplets and flow more easily. Furthermore, as the oil droplets suspension gets concentrated, it gets denser, and the oil removal efficiency Agunwamba et al.

4 , 2013 gets reduced. The tiny or small oil droplets coalesce and rises by the force of gravity and from bigger droplets, eventually the oil droplets floats to the surface thus, the separation of oil and Warf WATER could be achieved. The proposed separation technique is very much dependent on the arrangement and orientation of the varied no of BAFFLES and the BAFFLES spacing, other factors such as influent, concentration, flow rates, viscosity and specific gravity, using properties, volume of the system are undoubtedly playing important roles in removal or separation efficiency of the oil and Warf WATER . The features of the proposed SEPARATOR ; (a) Rectangular separation channels with varied no of BAFFLES concerning the horizontal velocity. (b) Equal interval of baffle spacing (c) Two outlet openings, one top and one below Applicability of varied no of BAFFLES 1) To promote laminar flow 2) To promote optimum oil WATER separation efficiency By using the principle of a maximum number of BAFFLES , a minimum distance for lighter oil droplets to rise and heat the baffle .

5 The baffle assists oil droplets to coagulate and float to the surface and be collected. The use of baffle facilities reduces the velocity of flow and the oil to be captured, reducing the concentration of effluent and enhancing oil removal efficiency. The design of the BAFFLES was such that it was m spacing intervals from each other, and the channel was m long, so the oil has to travel a distance of 15 cm in other to be collected. Droplets are released, when they become large enough that the buoyancy due to their size overcomes the attractive forces holding the droplets, the force trying to tear off the droplets is the frictional force is proportional to the flow velocity of the WATER . The proposed design of the BAFFLES is illustrated below; the slower the oil floated to the surface the better is its chances of being permanently separated from WATER .

6 The proposed SEPARATOR was to be designed as a rectangular channel with varied number of BAFFLES . The separation channel has the following assumptions. - Oil droplet rise as discrete, free sizing - Laminar Flow Reynolds Number < 1 - Separation is an ideal separation system with center-feed flow - Steady state with even distribution of flow entering and leaving the channel. Separation sizing and BAFFLES design The BAFFLES were designed as a square m x m and were welded at m from top to the depth of the channel and m from bottom to the top, and it was placed at m equal intervals, and the number of BAFFLES was varied for each of the channels. The intention of equal spacing is to provide flow passage for effluent to the outlet. The size of the channels is m x m x m and the capacity of the mixing tank is 200 li.

7 The pipe that connects the mixing tank to the channels is of diameter mm. The required Flow rate Q (m3/s) for each of the channels (Q) are , , , , Mixing tank set up and sample collection The primary function of the mixing tank in this experimental set up was to mix oil and WATER to form WATER and free oil solution with known concentration, the oil and WATER was mixed continuously with a mechanical stirrer to obtain a good mixture and it flowed from the pipe connected from the mixing tank to each of the varied baffled channels. An overhead tank was set up in order to Agunwamba et al., 2013 maintain a particular head in the mixing tank and the overhead tank was filled with a mixture of oil and WATER with the same concentration in the mixing tank. A volume of 200 li of oil WATER mixture, of oil was mixed with WATER , that is to say that li of oil was mixed with li of WATER to get a known concentration.

8 After stirring with mechanical stirrers for 5 mins, the sample was collected from the mixing tank, to test for the influent oil concentration. The valve was opened at 5 different flow rates for each of the 5 varied baffled channels; detention time was taken for each collection of samples, and the samples collected was tested for effluent oil concentration. However, 3 oils were used, 5 flow rates also used for each of the 5 channels that was varied with no of BAFFLES . Determination of oil concentration: When engine oil was used Folch method of extraction, reagents (chloroform, methanol) 50 ml of the sample was measured with a measuring cylinder and poured in a glass-stopped bottle. The sample macerated with 50 ml of chloroform and 25 ml of methanol and was homogenized; it was allowed to stand overnight.

9 25 ml of Nacl was added to the sample and thoroughly shaken and allowed to separate, two layers were formed (upper and lower layer), then the WATER forms an aqueous solution with Nacl at the upper layer. Two layers were separated using a separatory funnel, and the lower layer was evaporated using a rotary evaporator at 50 to 600C. The residue was weighed with the beaker and after which the residue was washed off, the beaker was oven dried and weighed. Then the mass of the residue was extrapolated when hydraulic oil was used. 3 mls of the sample was transferred into centrifuge tube containing ml of 20% of ammonium sulphate and shaken vigorously. 2 ml of of fluorescence in n-hexane was added and the mixture shaken vigorously for 5 mins, and then centrifuges at 3000 rpm for 10 mins, the absorbance of the lower layer was taken at 470 nm.

10 The concentration of the PAG (Poly-oxoakalyne Glycol) was extrapolated from a standard curve, determined with poly-oxoakalyne glycol as a standard, when groundnut oil was used. 1 ml of the sample was transferred into test tubes. 2 ml of conc. Sulphuric acid was added and boiled for 10 mins and allowed to cool. ml of the mixture was transferred into another tube. ml of phosphor vandlence reagent was added, mixed and allowed to stand in the dark for 45 mins. The absorbent was taken at 540 nm with spectrophotometer against plank. Determination of Oil Removal Efficiency Oil removal efficiency is mathematically calculated as Oil removal efficiency = Influent concentration - effluent concentration x 100 Influent concentration The results obtained in this research show the variation of oil removal efficiencies as a function five different flow rates and varied no BAFFLES in the channels.