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1 SPE Oil-Water Separation in Liquid-Liquid Hydroylones (LLHC) Experiment and Modeling Carlos Gomez, Juan Caldentey, Shoubo Wang, Luis Gomez, Ram Mohan and Ovadia Shoham, SPE, The University of Tulsa Copyright 1, Soiety of Petroleum Engineers In. This paper was prepared for presentation at the 1 SPE Annual Tehnial Conferene and Exhibition held in New Orleans, Louisiana, 3 September 3 Otober 1. This paper was seleted for presentation by an SPE Program Committee following review of information ontained in an abstrat submitted by the author(s). Contents of the paper, as presented, have not been reviewed by the Soiety of Petroleum Engineers and are subjet to orretion by the author(s). The material, as presented, does not neessarily reflet any position of the Soiety of Petroleum Engineers, its offiers, or members. Papers presented at SPE meetings are subjet to publiation review by Editorial Committees of the Soiety of Petroleum Engineers. Eletroni reprodution, distribution, or storage of any part of this paper for ommerial purposes without the written onsent of the Soiety of Petroleum Engineers is prohibited. Permission to reprodue in print is restrited to an abstrat of not more than 3 words; illustrations may not be opied. The abstrat must ontain onspiuous aknowledgment of where and by whom the paper was presented. Write Librarian, SPE, P.O. Box , Rihardson, TX , U.S.A., fax Abstrat The liquid-liquid Hydroylone (LLHC) has been widely used by the Petroleum Industry for the past several deades. A large quantity of information on the LLHC available in the literature inludes experimental data, omputational fluid dynami simulations and field appliations. The design of LLHCs has been based in the past mainly on empirial experiene. However, no simple and overall design mehanisti model has been developed to date for the LLHC. The objetive of this study is to develop a mehanisti model for the de-oiling LLHCs, and test it against available and new experimental data. This model will enable the predition of the hydrodynami flow behavior in the LLHC, providing a design tool for LLHC field appliations. A simple mehanisti model is developed for the LLHC. The required input for the model is: LLHC geometry, fluid properties, inlet droplet size distribution and operational onditions. The model is apable of prediting the LLHC hydrodynami flow field, namely, the axial, tangential and radial veloity distributions of the ontinuous-phase. The separation effiieny and migration probability are determined based on swirl intensity predition and droplet trajetory analysis. The flow apaity, namely, the inlet-to-underflow pressure drop is predited utilizing an energy balane analysis. An extensive experimental program has been onduted during this study, utilizing a MQ Hydroswirl hydroylone. The inlet flow onditions are: total flow rates between 7 to 18 gpm, oil-ut up to 1%, median droplet size distributions from 5 to 5 µm, and inlet pressures between 6 to 9 psia. The aquired data inlude the flow rate, oil-ut and droplet size distribution in the inlet and in the underflow, the rejet flow rate and oil onentration in the overflow and the separation effiieny. Additional data for veloity profiles were taken from the literature, espeially from the Colman and Thew (198) study. Exellent agreement is observed between the model predition and the experimental data with respet to both separation effiieny (average absolute relative error of 3%) and pressure drop (average absolute relative error of 1.6%). Introdution The petroleum industry has traditionally relied on onventional gravity based vessels, that are bulky, heavy and expensive, to separate multiphase flow. The growth of the offshore oil industry, where platform osts to aommodate these separation failities are ritial, has provided the inentive for the development of ompat separation tehnology. Hydroylones have emerged as an eonomial and effetive alternative for produed water deoiling and other appliations. The hydroylone is inexpensive, simple in design with no moving parts, easy to install and operate, and has low maintenane ost. Hydroylones have been used in the past to separate solid-liquid, gas-liquid and liquid -liquid mixtures. For the liquid -liquid ase, both dewatering and deoiling have been used in the oil industry. This study fouses only on the latter ase, namely, using the liquid-liquid hydroylones (LLHC) to remove dispersed oil from a water ontinuous stream. Oil is produed with signifiant amount of water and gas. Typially, a set of onventional gravity based vessels are used to separate most of the multiphase mixture. The small amount of oil remaining in the water stream, after the primary separation, has to be redued to a legally allowable minimum level for offshore disposal. LLHCs have been used suessfully to ahieve this environmental regulation. There is a large quantity of literature available on the LLHC, inluding experimental data sets and omputational fluid dynami simulations. However, there is still a need for more omprehensive data sets, inluding measurements of the underflow droplet size distribution. Additionally, there is a need for a simple and overall mehanisti model for the LLHC. The objetive of the present study is two fold: to develop a mehanisti model for the LLHC that an predit the flow behavior in the hydroylone and the oil/water separation effiieny; and to aquire new experimental data for the

2 C. Gomez, J. Caldentey, S. Wang, L. Gomez, R. Mohan, O. Shoham SPE71538 LLHC, inluding detailed measurements of the droplet size distributions in the inlet and underflow streams. The developed mehanisti model an be utilized for the design of LLHCs, providing the flexibility of designing alternative LLHC geometries for the same operating onditions for optimization purposes. It will also allow detailed analysis and performane predition for a given LLHC geometry and operating onditions, inluding separation effiieny and flow apaity (pressure drop flow rate relationship). LLHC Hydrodynami Flow Behavior. The LLHC, shown in Figure 1, utilizes the entrifugal fore to separate the dispersed phase from the ontinuous fluid. The swirling motion is produed by the tangential injetion of pressurized fluid into the hydroylone body. The flow pattern onsists of a spiral within another spiral moving in the same irular diretion (Seyda and Petty, 1991). There is a fored vortex in the region lose to the LLHC axis and a free-like vortex in the outer region. The outer vortex moves downward to the underflow outlet, while the inner vortex flows in a reverse diretion to the overflow outlet. Moreover, there are some re-irulation zones assoiated with the high swirl intensity at the inlet region. These zones, with a long residene time and very low axial veloity, have been found to be diminished as the flow enters the low angle taper setion (see Figure 1). An explanation of the harateristi reverse flow in the LLHC is presented by Hargreaves (199). With high swirl at the inlet region, the pressure is high near the wall region and very low toward the enterline, in the ore region. As a result of the pressure gradient profile aross the diameter, whih dereases with downstream position, the pressure at the downstream end of the ore is greater than at the upstream, ausing flow reversal. As the fluid moves to the underflow outlet, the narrowing ylone ross-setional area inreases the fluid angular veloity and the entrifugal fore. It is due to this fore and the differene in density between the oil and the water, that the oil moves to the enter, where it is aught by the reverse flow and separated, flowing into the overflow outlet. Instead, if the dis persed phase is the heavier, like solid partiles, it will migrate to the wall and exit through the underflow. The amount of fluid going through the different outlets differs with heavy and light dispersion. It means that for these two different separation ases, two different geometries are needed (Seyda and Petty, 1991). In the deoiling ase, usually between 1 to 1 perent of the feed flow rate goes to the overflow. Another phenomenon that may our in a hydroylone is the formation of a gas ore. As Thew (1986) explained, dissolved gas may ome out of solution beause of the pressure redution in the ore region, migrating fast to the LLHC axis, and eventually emerging through the overflow outlet. A signifiant amount of gas an be tolerated but exessive amounts will disturb the vortex. An experimental study on this topi is found in Smyth and Thew (1996). LLHC Geometry. The deoiling LLHC onsists of a set of ylindrial and onial setions. Colman and Thew s (1988) design has four setions, as shown in Figure. The inlet hamber and the reduing setion are designed to ahieve higher tangential aeleration of the fluid, reduing the pressure drop and the shear stress to an aeptable level. The latter has to be minimized to avoid droplet breakup leading to redution in separation effiieny. The tapered setion is where most of the separation is ahieved. The low angle of this segment keeps the swirl intensity with high residene time. An integrated part of the design is a long tail pipe ylindrial setion in whih the smallest droplets migrate to the reversed flow ore at the axis and are being separated flowing into the overflow exit. This onfiguration gives a very stable small diameter reversed flow ore, utilizing a very small overflow port. Young et al. (199) ahieved similar results to Colman- Thew s LLHC, in terms of separation effiieny, with a different hydroylone onfiguration. Three setions were used instead of four. The reduing setion was eliminated and the angle of the tapered setion was hanged from 1.5º to 6º. Later, Young et al. (1993) developed a new LLHC design, whih resulted in an improvement in the separation performane. The prinipal modifiation of the enhaned design was a small hange in the tail pipe setion. A minute angle onial setion was used rather than the ylindrial pipe. Another important parameter in the LLHC geometry is the inlet onfiguration, as shown in Figure 3. Retangular and irular, single and twin inlets have been most frequently used by different researhers. The main goal is to injet the fluid with higher tangential veloity, avoiding the rupture of the droplets. The twin inlets have been onsidered to maintain better symmetry and for this reason maintain a more stable reverse ore (Colman et al., 198; Thew et al., 1984). Good results have also been ahieved with the involute single inlet design. The last element of the LLHC is the overflow outlet. This is a very small diameter orifie that plays a major role in the split ratio, defined as the relationship between the overflow rate and the inlet flow rate. Most of the ommerial LLHCs permit hanging the diameter of this orifie, depending on the range of operating onditions. Literature Review There are hundreds of literature referenes on the LLHC, inluding experimental studies, CFD simulations and modeling. Detailed review of these previous studies an be found in Caldentey () and Gomez (1). In this setion only pertinent mehastudies are reviewed briefly Two textbooks that ondense pioneering works on hydroylones and fundamental theories, inluding experimental data, design, and performane aspets, are Bradley (1965) and Svarovsky (1984). Both refer in most of the hapters to solid-liquid hydroylones, with only a small setion available on liquid-liquid separation and other appliation areas.

3 SPE71538 OIL-WATER SEPARATION IN LIQUID-LIQUID HYDROCYCLONES (LLHC)-EXPERIMENT AND MODENLING 3 Experimental Studies. Only a representative sample of previous experimental studies is summarized here. The review is divided into laboratory studies and design and appliation studies, as follows. Laboratory Studies. Earlier studies were presented by Simkin and Olney (1956), Sheng (1974), Johnson et al. (1976), Smyth et al. (198), Colman et al. (198) and Colman and Thew (198). A general revision of the hydroylone developed at Southampton University was arried out by Thew (1986), who also disussed some issues presented previously by Moir (1985). Other studies were published by Gay (1987), Bednarski and Listewnik (1988), Woillez and Shummer (1989) and Beeby and Niol (1993). Young et al. (199) measured the flow behavior in a Colman and Thew (198) type hydroylone, and later proposed a new modified design. In 1991, Weispfennig and Petty explored the flow struture in a LLHC using a visualization tehnique (laser indued fluoresene). The performane of a mini hydroylones, of 1 mm-diameter, were studied by Ali et al. (1994) and Syed et al. (1994). Design and Appliations. A summary of the seletion, sizing, installation and operation of hydroylones was provided by Moir (1985). Meldrum (1988) desribed the basi design and priniple of operation of the de-oiling hydroylone. Choi (199) tested a system of six hydroylones (35 mm diameter) operating in parallel for produed water treatment (PWT). The performane of three ommerial liquid-liquid hydroylones (two stati and one dynami) in an oil field was evaluated by Jones (1993). CFD Simulations. Numerial simulations or CFD are used widely to investigate flow hydrodynamis. As expressed by Hubred et al. (), the solution of the Navier Stokes Equations for simple or omplex geometry for non-turbulent flow is feasible nowadays. But urrent omputational resoures are unable to attain the instantaneous veloity and pressure fields at large Reynolds numbers even for simple geometries. The reason is that traditional turbulene models, suh as k-?, are not suitable for this omplex flow behavior. On the other hand, more realisti and ompliated turbulene models inrease the omputational times to inonvenient limits. The flow in hydroylones has been numerially simulated by Rhodes et al. (1987), Hsieh and Rajamani (1991) (see also Rajamani and Hsieh, 1988; Rajamani and Devulapalli, 1994) and He et al. (1997). In most of these studies the models were evaluated through omparison with laser-doppler anemometry (LDA) data. Many researhers have used this tehnique to measure the veloity field and turbulene intensities (Dabir, 1983; Fanglu and Wenzhen, 1987; Jirun et al., 199; and Fraser and Abdullah, 1995). Modeling. Although widely used nowadays, the seletion and design of hydroylones are still empirial and experiene based. Even though quite a few hydroylone models are available, the validity of these models for pratial appliations has still not been established (Kraipeh et al., ). A thorough review of the different available models an be found in Chakraborti and Miller (199) and Kraipeh et al. (). The LLHC models an be divided into empirial and semi -empirial, analytial solutions and numerial simulations (Chakraborti and Miller, 199). The empirial approah is based on development of orrelations for the proess key parameters, onsidering the LLHC as a blak box. The semiempirial approah is foused on the predition of the veloity field, based on experimental data. The analytial and numerial solutions solve the non-linear Navier-Stokes Equation. The former one is a mathematial solution, whih is ahieved negleting some of the terms of the momentum balane equation. The numerial solution uses the power of omputational fluid dynamis to develop a numerial simulation of the flow. As Svarovsky (1996) omments, it seems that the analytial flow models have been abandoned in favor of numerial simulations due to the omplexity of the multiphase flow phenomena. From extensive experimental tests, Colman and Thew (1983) developed some orrelations to predit the migration probability urve, whih defines the separation effiieny for a partiular droplet size in a similar way that the grade effiieny does for solid partiles. Seyda and Petty (1991) evaluated the separation potential of the ylindrial tail pipe setion. A semi-empirial model to predit the veloity field in a ylindrial hamber was developed to alulate the partile trajetories, and hene, the grade effiieny. Wolbert et al. (1995) presented a omputational model to determine the separation effiieny based on the analysis of the trajetories of the oil droplets. An extension of Bloor and Ingham (1973) LLHC model was presented by Moraes et al. (1996). The modifiation takes into aount the differene in the split ratio for liquid-liquid and solid-liquid hydroylones. The literature review onfirms the need for aurate experimental data utilizing appropriate sampling proedure and inluding the measurements of the droplet size distributions at the inlet and underflow setions, and the need to develop a simple mehanisti model for the LLHC. These defiienies are addressed in the present study. Experimental Program This setion desribes the experimental faility, working fluids, definitions of pertinent separation parameters, and the experimental results of the LLHC. Experimental Faility. The experimental three-phase, oilwater-gas, flow loop is shown Figure 4. The oil-water-gas indoor flow faility is a fully instrumented state-of-the-art two-inh flow loop, enabling testing of single separation equipment or ombined separation systems. The test loop onsists of four main omponents: storage and metering setion, LLHC test setion, downstream oil-water separation faility, and data aquisition system. Following is a brief desription of these setions. Storage and Metering Setion. Oil and water are stored in two tanks of 4 gallons apaity eah. Eah tank is onneted to two pumps. The first one is a 3656 model pump, 1x-8 size,

4 4 C. Gomez, J. Caldentey, S. Wang, L. Gomez, R. Mohan, O. Shoham SPE71538 ast iron onstrution with bronze impeller, John Crane Type 1 mehanial seal, 1 HP motor and operates at 36 rpm. It delivers 5 18 psig. The seond one is a 3656 Model pump, 1.5x-1 size, ast iron onstrution with bronze impeller, John Crane Type 1 mehanial seal, 5 HP motor and operates at 36 rpm. It delivers psig. Both pumps are equipped with return lines. Eah fluid is pumped from the storage tank to the metering setion. The metering setion omprises of pressure gages, ontrol valves, variable speed ontrollers and state-of-the-art Miromotion net oil omputers (NOC), whih provide the total mass flow rate, water-ut, temperature, and mixture density. The signals from the flow meters and ontrol valves are fed to the data aquisition system, whih will be desribed later. Chek valves to prevent any bak-flow are installed downstream of the ontrol valves. The metered oil and water are then ombined in a mixing-tee to obtain oil-water dispersion. Additionally, a stati mixer is available in parallel to the mixing-tee for homogenization of the flow. Test Setion. Figure 5 shows a shemati of the LLHC test setion and Figure 6 presents a photograph of the LLHC prototype installed in the test setion. The LLHC is a -inhes NATCO MQ Hydro Swirl Hydroylone mounted vertially with a total height of 6 inhes. Water flows into the test setion through a pipe oming from the water tank. This pipe has a split setion where the water split stream mixes with oil in order to get thorough mixing with the desired oil onentration. The split setion is a ½ inh pipe omposed of a water wheel paddle meter, a mixing tee and a stati mixer. Oil for the mixture is pumped from a 55 gallons barrel with a gear pump, and metered by means of a gear flow meter. One the oil and water are mixed, they pass through a stati mixer in order to get a desired droplet size distribution. After this point the mixture is direted to the main stream pipe entering it by means of an inverse pitot tube. One the mixture enters the main stream line, it an either flow diretly to the test setion or be subjeted to an additional mixing loop where smaller droplet size distributions an be ahieved. The mixture an be sent to either the MQ steel hydroylone or the MQ aryli hydroylone. The latter LLHC, whih has the same harateristis as the steel one, is plaed for observation purposes. In order to measure the droplet size dis tribution, a speial isokineti sampler is designed and operated in order to get representative aurate measurements of the distributions, as shown in Figure 7. Samples from both the inlet and underflow streams an be obtained. One the sample is taken, it is plaed in the droplet size distribution analyzer. For this purpose, a Laser sattering devie, namely, the Horiba LA -3 analyzer is used to analyze the samples.. It may be noted that a surfatant-based additive is utilized, as shown in Figure 7, to avoid oalesene in the sample when transferred and run in the droplet size analyzer The flow in the LLHC is split into two streams: The overflow stream, with mainly oil, and the down-flow stream, with mainly water. The overflow is disharged into a 55 gallons barrel and the underflow is sent to the downstream three-phase separator. Pressure transduers are loated on the upper and the lower outlets of the LLHC. The underflow stream passes through a metering setion, loated upstream of the three-phase separator, where flow rate, density, temperature and water ut are measured using a liquid Miromotion oriolis mass flow meter. Due to the small oil onentration in some of the experiments, a speial oil ontent analyzer is utilized to measure the oil onentration of the underflow. This equipment is a Horiba OCMA model that uses infrared spetrosopy tehnique. Downstream Oil-Water Separation Setion. The 58 gallon three-phase flow separator loated downstream of the LLHC test setion operates at 1 psig. It onsists of three ompartments. In the first ompartment the oil-water mixture is stratified and the oil flows into the seond ompartment through flotation. In this ompartment, there is a level ontrol system that ativates a ontrol valve disharging the oil into the oil storage tank. The water flows from the first ompartment to the third ompartment through a hannel loated below the seond ompartment. In this ompartment, there is also a level ontrol system, allowing water to flow into the water storage tank. Data Aquisition System. IDM variable speed ontrollers installed on all the 4 pumps ontrol the oil and water flow rates into the test setion. The flow loop is also equipped with several temperature sensors and pressure transduers for measurement of the in-situ temperature and pressure onditions. All output signals from the sensors, transduers, and metering devies are olleted at a entral panel. A state-ofthe-art data aquisition system, built using LabView, is used to both ontrol the flow in the loop and also to aquire data from analog signals transmitted from the instrumentation. The program provides variable sampling rates. The sampling rate was set at Hz for a minutes sampling period. The final measured quantity results from an arithmeti averaging of 1 readings, after steady-state ondition is established. A regular alibration proedure, employing a highpreision pressure pump, is performed on eah pressure transduer at a regular shedule, to guarantee the preision of measurements. The temperature transduer onsists of a Resistane Temperature Detetor (RTD) sensor and an eletroni transmitter module. Working Fluids. Tap water and mineral oil were hosen and a dye (red) was added to the oil to improve flow visualization between the phases. The oil has low emulsifiation, fast separation, appropriate optial harateristis, non-degrading properties, and is non-hazardous. The properties of the oil are API=33.7 and µ O = 13.6 P at 1 F. During all the experimental runs the average temperature in the flow loop varied between 7 and 8 F. Definition of Separation Parameters. Following are the definitions of two important parameters used in this study to define the total separation effiieny:

5 SPE71538 OIL-WATER SEPARATION IN LIQUID-LIQUID HYDROCYCLONES (LLHC)-EXPERIMENT AND MODENLING 5 Split Ratio: The split ratio is the ratio of the overflow rate to the inlet flow rate, as given below: q overflow F = 1% (1) q inlet where F is the split ratio, q overflow is the total flow rate at the upper outlet of the LLHC, and q inlet is the total inlet flow rate. Oil Separation Effiieny: Pratial interpretation of separation data is onerned with the purity of individual disharge streams. Many referenes quantify the relative phase omposition of the separated streams in the form of a perentage by volume measurement. In this study a widely used definition is adapted for the oil separation effiieny, namely, q oil overflow ε ff = 1 % () q oil inlet where q oil-overflow is the flow rate of oil at the overflow, q oil-inlet is the flow rate of oil at the inlet. Utilizing ontinuity relationship, Equation () beomes q underflow oil underflow ε = ( 1 ) 1% (3) ff q inlet oil inlet Note that when oil-underflow tends to zero, the separation effiieny is maximum. Experimental Results. A total of 14 runs were onduted in this study. The data is analyzed and presented, so as to demonstrate the effet of the flow variables on the separation effiieny, as given in the following setions. Effet of Pressure Drop and Flow Rate. The separation of oil droplets in the swirl hamber of the hydroylone is a result of the fores imposed on the oil droplets in the spinning fluid and the residene time in the hamber. Lower flow rates mean longer residene times but lower aeleration fores. Conversely higher flow rates result in higher aeleration fores and smaller residene times. As shown in Figure 8, the MQ Hydroswirl performane is independent of flow rate in the range tested. For hydroylones of similar geometries, the literature reports similar results. Effet of Underflow Pressure. Bak pressure must be applied at the hydroylone underflow, in order to fore the ore stream ontaining the oil to the overflow; otherwise, all the flow will exit through the underflow and no separation would our. For a given underflow bakpressure, if the overflow pressure is slowly inreased, the ore diameter inreases, ultimately resulting in part of the oil ore disharging out through the underflow. The MQ Hydroswirl performane is independent of the underflow pressure, as shown in Figure 9, provided there is suffiient bakpressure to fore enough flow out of the overflow (Young et al. 199). It is ritial that onstant bak pressure be applied, sine swings in bakpressure result in the oil in the ore being rapidly disharged with the leaned water. Effet of Overflow Diameter. Separation effiieny of LLHCs is independent of overflow diameter (Young et al. 199). This is onfirmed by the results of this study, as shown in Figure 1. However, the minimum overflow rate to make an effetive separation inreases with inreasing overflow diameter. The minimum flow rate for eah orifie opening size is a result of a minimum veloity required for the oil to move to the overflow (Young et al. 199). This minimum veloity multiplied by the ross setional area of the overflow results in a minimum flow rate for effetive separation for eah overflow opening size. Inreasing overflow size results in an inreased amount of water, whih must be removed with the oil to obtain the same removal effiieny. This of ourse means that a greater flow rate of oily wastewater must be reproessed. The major advantage of larger overflow diameters is that it allows more oil to be removed without affeting the purity of the underflow water stream when large slugs of oil are enountered in field operations. Furthermore, larger outlets are not as suseptible to blokage as the smaller ones. Figure 1: Effet of overflow diameter on effi ieny Effet of Inlet Oil Conentration. Field reports indiate that with inreased oil onentrations, the performane of the MQ Hydroswirl hydroylone improves and an handle the additional oil. As an be observed in Figure 11, separation is independent of inlet oil onentration when there is adequate flow at the overflow to remove the required amount of oil. The improved separation of field installations with inreasing oil ontent is probably due to the presene of larger oil droplet sizes. Effet of Oil Droplet Size Distribution. The variable having the greatest impat on oil-water separation is the oil droplet size distribution. Figure 1 shows the separation performane of the MQ Hydroswirl hydroylone for several droplet size distributions, with the median droplet size shown. As an be seen, the oil separation effiieny inreases with inrease in the droplet size. This an be intuitively expeted as the larger oil droplets oalese faster than the smaller ones. Typial results for the droplet size distributions in the inlet and underflow streams are given in Figure 13. This figure demonstrates the removal of the large droplets from the feed stream. Also, the underflow stream ontains smaller droplets sizes, as ompared to the inlet stream, due to breakup of droplets in the LLHC. Mehanisti Modeling The following setions provide details of the mehanisti model developed for the LLHC in the present study. Swirl Intensity. The swirl intensity is defined as the ratio of the loal tangential momentum flux to the total momentum flux. The swirl intensity equation given below is a modifiation of the Mantilla (1998) orrelation, based on Erdal (1) CFD simulations, given by

6 6 C. Gomez, J. Caldentey, S. Wang, L. Gomez, R. Mohan, O. Shoham SPE M t.15 Ω =.49 Re I ( tan( β ) ) MT.1 ( 1+ tan( ) ) M t 4 1 z EXP I β M T Rez D where M t /M T is the ratio of the momentum flux at the inlet slot to the axial momentum flux at the harateristi diameter position, alulated as: M M t T mv & = mu & is av m & / ρ = m & / ρ A A is A = A The variables in the above equations are: O is the swirl intensity, Re is the Reynolds number, ß is the semi-angle of the onial setions, D is the harateristi diameter of the LLHC (measured where the angle hanges from the reduing setion to the tapered setion in the Colman and Thew s Design, and at the top diameter of the 3º tapered setion of the Young s Design), z is the axial position starting from D, V is is the veloity at the inlet, U av is the average axial veloity at D, m& is the mass flow rate, A is the ross setional area at D and A is is the inlet ross setional area. The Reynolds number is defined in the same way as for pipe flow with the aution that it refers to a given axial position, yielding: Re ρ U D is (4) avz z z = (6) µ where µ is the visosity of the ontinuous fluid. The inlet fator, I, as suggested by Erdal (1), is defined as: n I = 1 EXP (7) where n = 1.5 for twin inlets and n = 1 for involute single inlet. Veloity Field. The swirl intensity is related, by definition, to the loal axial and tangential veloities. Therefore, it is assumed that one the swirl intensity is predited for a speifi axial loation, it an be used to predit the veloity profiles. Both the tangential and axial veloities are alulated following a similar proedure as proposed by Mantilla (1998). The radial veloity, whih is the smallest in magnitude, is omputed onsidering the ontinuity equation and the wall effet. Tangential Veloity. It has been onfirmed experimentally that the tangential veloity is a ombination of a fored vortex near the hydroylone axis, and a free-like vortex in the outer wall region, negleting the effet of the wall boundary layer, (5) as shown in Figure 14. This type of behavior is known as a Rankine Vortex. Algifri et al. (1988) proposed the following equation for the tangential veloity profile: w T m r (8) = 1 EXP B U av r R R where w is the loal tangential veloity, whih is normalized with the average axial veloity, U av, at the harateristi diameter; R is the radius at the harateristi loation and r is the radial loation. The term T m represents the maximum momentum of the tangential veloity at the setion and B determines the radial loation at whih the maximum tangential veloity ours. The following expressions were obtained by urve-fitting several sets of the experimental data. T = Ω (9) m Involute Single Inlet: B Twin Inlets: B 1.7 = 55.7 Ω (1).35 = 45.8 Ω (11) It an be seen that the above equations are only funtions of the swirl intensity, O. Thus, for a given axial position, the tangential veloity is only funtion of the radial loation and the swirl intensity. Axial Veloity. In swirling flow the tangential motion gives rise to entrifugal fores whih in turn tend to move the fluid toward the outer region (Algifri 1988). Suh a radial shift of the fluid results in a redution of the axial veloity near the axis, and when the swirl intensity is suffiiently high, reverse flows an our near the axis. This phenomenon auses a harateristi reverse flow around the LLHC axis, whih allows the separation of the different density fluids. A typial LLHC axial veloity profile is illustrated in Figure 15. Here, the positive values represent downward flow near the wall, whih is the main flow diretion, and the negatives values represent upward reverse flow near the LLHC axis. The flow reversal radius, r rev, is the radial position where the axial veloity is equal to zero. To predit the axial veloity profile, a third-order polynomial equation is used with the proper boundary onditions. The general form is as follows: u ( r ) = a + (1) 3 1r + ar + a3r a4 where a 1, a, a 3 and a 4 are onstants. The boundary onditions onsidered are: du( r = Rz ) 1. = dr The veloity is maximum at the wall;

7 SPE71538 OIL-WATER SEPARATION IN LIQUID-LIQUID HYDROCYCLONES (LLHC)-EXPERIMENT AND MODENLING 7. u( r = rrev ) = Zero veloity at the loation of reverse flow, r rev ; du( r = ) 3. = dr 4. Rz u( r )rdr U avz The veloity is symmetri about the LLHC axis; and πρ = ρ πr Mass onservation. Substituting the boundary onditions in Equation (1) yields the axial veloity profile, whih is a funtion of the swirl intensity, O only: 3 u r 3 r.7 1 U = + + avz C Rz C Rz (13) C r r rev rev C = 3.7 R z R (14) z r Rz rev.3 =.1Ω (15) Several assumptions are impliit in these equations. First, axisymetri geometry is imposed. Then, the effets of the boundary layer are negleted, and finally the mass onservation balane does not onsider the split ratio. The last assumption an be onsidered a good approximation for small values of split ratios used in the LLHC, usually less than 1%. Radial Veloity. The radial veloity, v, of the ontinuous phase is very small, and has been negleted in many studies. In our ase, in order to trak the position of the droplets in ylindrial and onial setions, the ontinuity equation and wall onditions suggested by Kelsall (195) and Wolbert (1995) are used for the radial veloity profile, yielding: r v = utan( β ) (16) R z The radial veloity is a funtion of the axial veloity and geometrial parameters. In the partiular ase of ylindrial setions, where tan(ß) =, the radial veloity, v, is equal to. Droplet Trajetories. The droplet trajetory model is developed using a Lagrangian approah in whih single droplets are traed in a ontinuous liquid phase. The droplet trajetory model utilizes the flow field presented in the previous setion. Figure 16 presents the physial model. A droplet is shown at two different time instanes, t and t + dt. The droplet moves radially with a veloity V r and axially with V z. It is assumed that in the tangential diretion the droplet veloity is the same as the ontinuous fluid veloity, as no fore ats on the droplet in this diretion. Therefore, the trajetory of the droplet is presented only in two dimensions, namely r and z. z During a differential time dt, the droplet moves at veloity V r = dr/dt in the radial diretion and V z = dz/dt in the axial diretion. Combining these two equations and solving for the axial distane yields the governing equation for the droplet displaement: dz dr dz = dt Vz Vz = z = dr dr Vr Vr dt (17) Negleting the axial buoyany fore (no-slip ondition), the droplet axial veloity V z is equal to the axial veloity of the fluid, u. This simplifiation is reasonable when the aeleration due to the entrifugal fore in the radial diretion is thousand times larger than the aeleration of gravity. Due to this aspet, the LLHC is not sensitive to external movements and it an be installed either horizontally or vertially. The droplet veloity in the radial diretion is equal to the fluid radial veloity, v, plus the slip veloity, V sr. Rearranging Equation (17) yields the total trajetory of the droplet, namely: r r u r r r1 v V = = = (18) + sr z The only unknown parameter in Equation (18) is the slip veloity, whih an be solved from a fore balane on the droplet in the radial diretion, as shown Figure 16. Assuming a loal equilibrium momentum yields: 3 w πd 1 πd ( ρ ρd ) = CD ρvsr (19) r 6 4 where the left side of the equation is the entripetal fore, and the right side is the drag fore. Solving for the radial slip veloity, results in: V sr 4 ρ = 3 ρ ρ d w r d C D 1 () where d is the droplet diameter,? d is the density of the dispersed phase,? is the density of the ontinuous phase and C D is the drag oeffiient alulated using the following relationship (Morsi and Alexander, 197 and Hargreaves, 199): b b = (1) Re C D b1 + + Red 3 d where the oeffiients b are dependent on the Reynolds Number of the droplets, defined as: ρ d Re d µ V = sr ()

8 8 C. Gomez, J. Caldentey, S. Wang, L. Gomez, R. Mohan, O. Shoham SPE71538 The values for the b oeffiients, as funtions of the range of Re d, are shown in Table 1: Finally, a numerial integration of Equation (18) determines the axial loation of the droplet as a funtion of the radial position. The trajetory of a given size droplet is mainly a funtion of the LLHC veloity field and the physial properties of the dispersed and ontinuous phases. Separation Effiieny. The separation effiieny of the LLHC an be determined based on the droplet trajetory analysis presented above. Starting from the ross setional area orresponding to the LLHC harateristi diameter, it is possible to follow the trajetory of a speifi droplet, and determine if it is either able to reah the reverse flow region and be separated, or if it reahes the LLHC underflow outlet, dragged by the ontinuous fluid and arried under. As illustrated in Figure 17, the droplet that starts its trajetory from the wall (r = R) does not reah the flow reversal radius, and thus is not separated but rather arried under. However, if the starting loation is at r < R, the hane of this droplet to be separated inreases. When the starting point of the droplet trajetory is the ritial radius, r rit, the droplet reahes the reverse radius, r rev, and is arried up by the reverse flow and is separated. Therefore, assuming homogeneous distribution of the droplets, the effiieny for a droplet of a given diameter, e(d), an be expressed by the ratio of the area within whih the droplet is separated, defined by r rit, over the total area of flow. This assumption has also been applied by other researhers (Seyda and Petty, 1991; Wolbert et al., 1995 and Moraes et al., 1996). As proposed by Moraes et al. (1996), the effiieny is given by:, if rrit = rrev πrrit πrrev ε ( d ) =, if rrev < rrit < R (3) πr πrrev 1, if rrit = R Repeating this proedure for different droplet sizes, the migration probability urve is obtained as shown in Figure 18. This funtion has an S shape and represents the separation effiieny, e(d), vs. the droplet diameter, d. It an be seen that small droplets have an effiieny very lose to zero and as the droplet size is inreased, e(d) inreases sharply until it reahes d 1, whih is the smallest droplet size with a 1% probability to be separated. The migration probability urve is the harateristi urve of a partiular LLHC for a given flow rate and fluid properties. This urve is independent of the feed droplet size distribution and is used in many ases to evaluate the separation of a given LLHC onfiguration. Using the information derived from the migration probability urve and the feed droplet size distribution, the underflow purity, e u, an be determined as follows: ε( di )V i i ε u = (4) V i i where e u is expressed in %, and V i is the perentage volumetri fration of the oil droplets of diameter d i. The underflow purity is the parameter that quantifies the LLHC apaity to separate the dispersed phase from the ontinuous one. Pressure Drop. The pressure drop from the inlet to the underflow outlet is alulated using a modifiation of the Bernoulli s Equation: P is 1 + ρ V is = P u 1 + ρ U u + ρ (h f + h f ) + ρ gsinθ L (5) where? is the density of the ontinuous phase; P is and P u are the inlet and outlet pressures, respetively; V is is the average inlet veloity and U u is the underflow average axial veloity; L is the hydroylone length,? is the angle of the LLHC axis with the horizontal; h f orresponds to the entrifugal fore losses and h f is the fritional losses. The fritional losses are alulated similar to that of pipe flow: h f ( z z Vr ( z ) ) = f ( z ) (6) D( z ) where f is the frition fator and V r is the resultant veloity. In the ase of onial setions, all parameters in Equation (6) hange with the axial position, z. The onial setion is divided into m segments and assuming ylindrial geometry in eah segment, the fritional losses an be onsidered as the sum of the losses in all the m segments, as follows. h f (onial ) Z m?z Vr ( at ( n 1) ) = f ( z) (7) n= 1 Dn 1 + Dn The resultant veloity, V r, is alulated as the vetor sum of the average axial and tangential veloities, The annular downward flow region is only onsidered, as presented in the following set of equations: V ( z ) = U + W (8) R Z π R z Z = Wrdrdφ rrev W z π (9) Rz rdrd φ rrev For simplifiation purposes, the average axial veloity in Equation (8), Uz, is alulated assuming plug flow, namely, Uz is equal to the total flow rate over the annular area from the wall to the reverse radius, r rev. The Moody frition fator is alulated using Hall s Correlation (Hall, 1957).

9 SPE71538 OIL-WATER SEPARATION IN LIQUID-LIQUID HYDROCYCLONES (LLHC)-EXPERIMENT AND MODENLING 9 f ( z ) = x1 4 ε + D( z ) 1 6 Re( z ) 1 / 3 (3) where e is the pipe roughness and Re is the Reynolds Number, alulated based on the resultant veloity omputed in Equation (8). The entrifugal losses are the most important ones in Equation (5), and aount for most of the total pressure drop in the LLHC. They are alulated using the following expression: R ( nw = u u ) ( r ) h f dr (31) rrev r where W u is alulated from Equation (9) at the underflow outlet and the entrifugal fore orretion fator, n = for twin inlets, and n = 3. for involute single inlet. The entrifugal fore orretion fator ompensates for the use of Bernoulli s Equation under a high rotational flow ondition. Its meaning is similar to the kineti energy oeffiient used to ompensate for the non-uniformity of the veloity profile in pipe flow (Munson et al., 1994). Rigorously, the Bernoulli equation is valid for a streamline and the summation of the pressure, the hydrostati and the kineti terms an only be onsidered onstant in the entire flow field if the vortiity is equal to zero. Numerial Solution. The simulation ode based on the developed mehanisti model uses mainly two different numerial methods to obtain the results. The tangential veloity, given by Equation (9), is solved using the Trapezoidal Rule, and for the droplet trajetory, a fourth-order Runge-Kutta method is used to solve Equation (18). Also, a ommerial program (Mathematia 4.) was used to verify the resulting numerial values given by the omputer ode. Resusults and Disussion This setion presents omparison between the LLHC mehanisti model preditions and experimental data taken either at the present study or from the literature. Comparisons are made for the swirl intensity, veloity profiles, migration probability, pressure drop, droplet size distribution and global separation effiieny. Swirl Intensity. The swirl intensity, whih is the ratio of the loal tangential momentum flux to the total momentum flux, an be obtained from Equation (4). Figure 19 provides the omparison between the model preditions and the Colman and Thew (198), Case data. Note that only 1 data point is plotted, due to availability of axial and tangential veloity measurements at speifi axial loation. The results display the swirl intensity versus the dimensionless axial position, where z is the axial distane from the harateristi diameter, that is the loation where the tapered setion begins. Good agreement is observed between the data point and the model preditions. It has been experimentally proven by several researhers that the swirl intensity deays exponentially with axial position due to the wall fritional losses (Mantilla, 1998). The model preditions show the same trend Veloity Profile. The veloity field predited by the mehanisti model is ompared with the same experimental data set used for the swirl intensity omparison, namely, Case. Figure presents the omparison between the experimental data and model predition for the tangential veloity. The y-axis orresponds to the axis of the LLHC, and the x-axis represents the radial position. The units used originally were onserved, namely, millimeters per seond for the tangential veloity, and millimeters for the radial position. The model predits with aeptable auray the tangential veloity at the wall, the peak veloity and the radius where it ours. The experimental data and the model display a Rankine Vortex shape, namely, a ombination of fored vortex near the LLHC axis and a free like vortex at the outer region. The axial veloity profile predited by the model is next ompared with the experimental data in Figure 1. The positive values of axial veloities orrespond to downward flow, whih is the diretion of the main flow, while the negative values represent the reverse flow. The mehanisti model performane is exellent with respet to the axial veloity in the downward flow region, and not so good in the reverse flow region. Considering the alulations that the model follows to ompute the separation effiieny, the predition of the reverse flow veloity profile is not so important. What is really important is the predition of the radius of zero veloity (r rev ) sine beyond this point the droplet is assumed to be separated, moving upwards to the overflow exit. Migration Probability: A omparison between the model preditions of the migration probability urve as ompared with experimental data of Colman and Thew (198) is given in Figure. Fair agreement is observed with the data. Pressure Drop. A omparison between the predited pressure drop and experimental data from the present study is shown in Figure 3, while Figure 4 shows the model preditions of pressure drop vs. flow rate as ompared with the experimental data taken by Young et al. (199). Very good agreement is observed in both ases, with an average absolute relative error of 1.6%. Droplet Size Distribution. Figure 5 shows a omparison between the model preditions and experimental data of the droplet size distribution for runs 11. As shown in the figures, good agreement is observed with experimental results. The model predition urves for the underflow droplet size distribution are shifted to the right, whih means that the model predits effiieny smaller than the experimental one. Also there is a disontinuity in the model urve beause the model doesn t onsider either breakup or oalesene. This

10 1 C. Gomez, J. Caldentey, S. Wang, L. Gomez, R. Mohan, O. Shoham SPE71538 means that the smallest droplet that enters the LLHC is also the smallest one that is found in the underflow stream. On the other hand, the largest droplet in the underflow stream is the largest droplet with a alulated effiieny below 1%. Global Separation Effiieny. Both the underflow purity and the migration probability urve predited by the model are evaluated through omparisons with experimental data. Table presents a omparison with the experimental data taken at the present study for a representative sample of the 14 runs, and Table 3 shows a omparison with literature experimental data, where ases 9 to are part of the set of experiments published by Colman et al. (198). These experimental data sets are for the LLHC onfiguration given in Table 4. The harateristi diameter and operational onditions are reported in Table 3. As an be seen from both tables and 3, the model preditions are in exellent agreement with both data sets, with an average absolute relative error of 3%. The results are also plotted in Figures 6 and 7, respetively. Summary and Conlusions A new faility for testing LLHCs was designed, onstruted and installed in an existing three-phase flow loop. The test setion is fully instrumented to measure the important flow and separation variables, inluding flow rates (inlet, underflow and overflow) and the respetive oil onentrations; droplet size distributions (inlet and underflow streams); pressures (inlet and underflow) and temperature. A mixer bypass loop enables the generation of a wide range of droplet size distributions. A set of 14 experimental runs was onduted, with inlet total flow rates between 18 to 6 GPM, inlet oil uts between to 1%, inlet droplet size distributions with droplet medians between 3 to 16 mirons, inlet pressures from 6 to 9 psia, underflow pressures between 35 to 63 psia, temperature between 65ºF 8ºF, and overflow rejet diameter of 3mm and 4mm. The olleted data permitted the alulation of the LLHC separation effiieny for eah of the runs. The olleted data reveals that LLHCs an be used up to 1% inlet oil onentrations, maintaining high separation effiieny. However, the performane of the LLHC is best for very low oil onentrations at the inlet, below 1%. For low onentrations, no emulsifiation of the mixture ours in the LLHC. However, high inlet onentrations, up to 1%, promote emulsifiation posing a separation problem in the overflow stream. A simple mehanisti model is developed for the LLHC. The model is apable of prediting the LLHC hydrodynami flow field, namely, the axial, tangential and radia l veloity distributions of the ontinuous-phase. The separation effiieny and migration probability are determined based on swirl intensity predition and droplet trajetory analysis. The flow apaity, namely, the inlet-to-underflow pressure drop is predited utilizing an energy balane analysis. The predition of the LLHC model was ompared against the data from both the present study and published data for veloity profiles from the literature, espeially from the Colman and Thew (198). Good agreement is obtained between the model preditions and the experimental data with respet to both separation effiieny (average absolute relative error of 3%) and pressure drop (average absolute relative error of 1.6%). Nomenlature A = ross setional area B = peak tangential veloity radius fator (Eqs. 1 and 11) = Conentration C D = drag oeffiient d = droplet diameter D = diameter D = LLHC harateristi diameter f = frition fator F = Split ratio g = gravity aeleration h = losses I = inlet fator L = length m = Nº of segments m& = mass flow rate M t = momentum flux at the inlet slot M T = axial momentum flux at the harateristi diameter position n = entrifugal fore orretion fator, number of inlets P = pressure q = volumetri flow rate r = radial position R = LLHC radius Re = Reynolds Number t = time T m = maximum tangential veloity momentum (Eq. 9) u = ontinuous phase loal axial veloity U = bulk axial veloity v = ontinuous phase loal radial veloity V = volumetri fration / veloity V r = droplet radial veloity V sr = droplet slip veloity in the radial diretion V z = droplet axial veloity w = ontinuous phase loal tangential veloity W = mean tangential veloity z = Axial position Greek Letters O = swirl intensity ß = taper setion semi -angle e = pipe roughness e ff = effiieny / purity? = axis inlination angle to horizontal µ = visosity? = density φ = Horizontal plane angle Subsripts av = average

11 SPE71538 OIL-WATER SEPARATION IN LIQUID-LIQUID HYDROCYCLONES (LLHC)-EXPERIMENT AND MODENLING 11 = harateristi diameter loation / ontinuous phase f = entrifugal rit = ritial d = dispersed phase / droplet f = fritional i = inlet is = inlet setion o = overflow r = resultant rev = reverse flow sr = Slip radial veloity u = underflow z = axial position Aknowledgments The authors thank Mr. Grant Young from Vortex Fluid Systems In. and Dr. Charles Petty from Mihigan State University for their help and advise during this study. Referenes 1. Algifri, A., Bhardwaj, R. and Rao, Y., 1988, Turbulene Measurements in Deaying Swirl Flow in a Pipe. Applied Sientifi Researh, Vol. 45, pp Ali, S., Wesson, G., Petty, C. and Parks, M., 1994, The Use of Small Hydroylones for Produed Water Clarifiation. Hydroylone Development Consortium, Mihigan State University. 3. Bednarski, S., and Listewnik, J.: "Hydroylones for Simultaneous Removal of Oil and Solid Partile from Ships' Oily Waters", Filtration and Separation, Marh/April 1988, pp Beeby, J.P., and Niol, S.K.: "Conentration of Oil-in- Water Emulsion Using the Air-Sparged Hydroylone", Filtration and Separation, Marh/April 1993, pp Bloor, M. and Ingham, D., 1973, "Theoretial Investigation of the Flow in a Conial Hydroylone". Trans. Instn. Chem. Engrs., Vol. 51, pp Bradley, D., 1965, "The Hydroylone". Pergamon Press. 7. Caldentey, J.,, A Mehanisti Model for Liquid Hydroylones. M.S. Thesis. The University of Tulsa, U.S.A. 8. Chakraborti, N. and Miller, J., 199, "Fluid Flow in Hydroylones: A Critial Review". Mineral Proessing and Extrative Metallurgy Review, Vol. 11, pp Choi, M.S, 199, "Hydroylone Produed Water Treatment for Offshore Developments", SPE Colman, D. and Thew, M., 198, "Hydroylone to Give a Highly Conentrated Sample of a Lighter Dispersed Phase". In International Conferene on Hydroylones, BHRA, Cambridge, United Kingdom, paper 15, pp Colman, D. and Thew, M., 1983, "Correlation of Separation Results From Light Dispersion Hydroylones". Chem. Eng. Res. Des., Vol. 61, pp Colman, D. and Thew, M., 1988, "Cylone Separator". U.S. Patent Colman, D., Thew, M. and Corney, D., 198, "Hydroylones for Oil/Water Separation". In International Conferene on Hydroylones, BHRA, Cambridge, United Kingdom, paper 11, pp Dabir, B., 1983, "Mean Veloity Measurements in a 3''- Hydroylone Using Laser Doppler Anemometry". Ph.D. Thesis. Mihigan State University, Mihigan. 15. Erdal, F., 1, Loal Veloity Measurements and CFD Simulations in GLCC Separators. Ph.D. Dissertation. The University of Tulsa, U.S.A. 16. Fanglu, G. and Wenzhen, L., 1987, "Measurements and Study of Veloity Field in Various Cylones by Use of Laser Doppler Anemometry". In 3rd International Conferene on Hydroylones, Wood, P. (ed), Elsevier, Oxford, England, pp Fraser, S. and Abdullah, M., 1995, "LDA Measurement on a Modified Cylone". ASME Laser Anemometry, FED- Vol. 9, pp Gay, J.C., 1987, "Rotary Cylone Will Omprove Oily Water Treatment and Redue Spae Requirement/Weight on Offshore Platforms", SPE Gomez, C., 1, Oil-WaterSeparation in Liquid-Liquid Hydroylones (LLHC) Experiment and modeling. M.S. Thesis. The University of Tulsa, U.S.A.. Hall, N., 1957, Thermodynamis of Fluid Flow. Longmans, Green, New York. 1. Hargreaves, J., 199, Computing and Measuring the Flow field in a Deoiling Hydroylone. Ph.D. Thesis. University of Southampton, England.. He, P., Saludean, M., Branion, R. and Gartshore, I., 1997, "Mathematial Modeling of Hydroylones". In ASME Fluids Engineering Division Summer Meeting, FEDSM Hsieh, K. and Rajamani, R., 1991, "Mathematial Model of the Hydroylone Based on Physis of Fluid Flow". AIChE Journal, Vol. 37, No. 5, pp Hubred, G., Mason, A., Parks, S. and Petty, C.,, "Dispersed Phase Separations: Can CFD Help?". Proeeding of ETCE/OMAE Conferene, New Orleans, Louisiana. 5. Jirun, X., Qian, L. and Qui, J., 199, "Studying the Flow Field in a Hydroylone With no Fored Vortex I, II". Filtration and Separation, July/August, pp , September/Otober, pp Johnson, R., Gibson, W.E., and Libby, D.R, 1976, "Performane of Liquid-Liquid Cylones", Ind. Eng. Chem. Fundam, Vol. 15, No.. 7. Jones, P.S.: "A Field Comparison of Stati and Dynami Hydroylone", SPE Prodution and Failities, May 1993, pp Kelsall, D., 195, "A Study of the Motion of Solid Partiles in a Hydrauli Cylone". Trans. Instn. Chem. Engrs., Vol. 3, pp Kraipeh, W., Chen, W. and Parma, F.,, "Predition of Hydroylone Performanes - How Muh Can the Models Do?". Amerian Filtration & Separation Soiety Annual Conferene, Myrtle Beah, SC, Marh Mantilla, I., 1998, Bubble Trajetory Analysis in Gas- Liquid Cylindrial Cylone Separators. M.S. Thesis. The University of Tulsa. 31. Meldrum, N., 1988, "Hydroylones: A Solution to Produed-Water Tratment". SPE Prodution Engineering, November, pp Moir, D.N.: "Seletion and Use of Hydroylones", The Chemial Engineer, January 1985, pp Moraes, C., Hakenberg, C., Russo, C. and Medronho, R., 1996, "Theoretial Analysis of Oily Water Hydroylones".

12 1 C. Gomez, J. Caldentey, S. Wang, L. Gomez, R. Mohan, O. Shoham SPE71538 In Hydroylones 96, Claxton, D., Svarovsky, L. and Thew, M. (eds), M.E.P., London, England, pp Morsi, S. and Alexander, A., 1971, An Investigation of Partile Trajetories in Two-Phase Flow Systems. Journal of Fluid Mehanis, Vol. 55, part, pp Rajamani, K. and Devulapalli, B., 1994, "Hydrodynami Modeling of Swirling Flow and Partiles Classifiation in Large-Sale Hydroylones". KONA Powder and Partile, No. 1, pp Rajamani, K. and Hsieh, K., 1988, "Hydroylone Model: A Fluid Mehani Approah". In Soiety of Mineral Engineers Annual Meeting, Phoenix, Arizona, preprint # Rhodes, N., Perileous, K. and Drake, S., 1987, "The Predition of Hydroylone Performane with a Mathematial Model". In 3rd International Conferene on Hydroylones, Wood, P. (ed), Elsevier, Oxford, England, pp Seyda, B. and Petty, C., 1991, "Separation of a Light Dispersion in a Cylindrial Vortex Chamber". Tehnial Report No. HDC-R6. Hydroylone Development Consortium, Mihigan State University. 39. Sheng, H.P., "Liquid-Liquid Separation in a Conventional Hydroylone", The Canadian Journal of Chemial Engineering, Vol. 5, August Simkin, D.J., and Olney, R.B., 1956, "Phase Separation and Mass Tranfer in a Liquid-Liquid Cylone", AICHE Journal, Vol., No. 4, pp Smyth, I. and Thew, M., 1996, A Study of the Effet of Dissolved Gas on the Operation of Liquid-Liquid Hydroylones. In Hydroylones 96, Claxton, D., Svarovsky, L. and Thew, M. (eds), M.E.P., London, England, pp Smyth, I., Thew, M., Debenham, P. and Colman, D., 198, Small-Sale Experiments on Hydroylones for Dewatering Light Oils. In International Conferene on Hydroylone, Cambridge, England, paper 14, pp Svarovsky, L., 1984, "Hydroylones". Holt, Rinehart & Winston. 44. Svarovsky, L., 1996, "A Critial Review of Hydroylones Models". In Hydroylones 96, Claxton, D., Svarovsky, L. and Thew, M. (eds), M.E.P., London, England, pp Syed, K.A., 1994, "The Use of Small Hydroylones for Produed Water Clarifiation", Mihigan State University. 46. Thew, M., 1986, "Hydroylone Redesign for Liquid- Liquid Separation". The Chemial Engineer, July/August, pp Thew, M., Wright, C. and Colman, D., 1984, "R.T.D. Charateristis of Hydroylones for the Separation of Light Dispersions". In nd International Conferene on Hydroylones, BHRA, Bath, England, paper E1, pp Weispfennig, K. and Petty, C., 1991, "Flow Visualization in a Confined Vortex Flow". Tehnial Report No. HDC- R5. Hydroylone Development Consortium, Mihigan State University. 49. Woillez, J., Shummer, P., 1989, "A New High Effiieny Liquid/Liquid Separator", BHRA, Multi-Phase Flow Proeedings of the 4th International Conferene, pp Wolbert, D., Ma, B. and Aurelle, Y., 1995, "Effiieny Estimation of Liquid-Liquid Hydroylones Using Trajetories Analysis". AIChE Journal, Vol. 41, No. 6, pp Young, G., Taggart, D. and Hild, D., 1993, Improved Understanding of Deoiling Hydroylones Leads to Signifiant Performane Improvement. Produed in Amoo Prodution Company Researh Department Tulsa Prodution Researh Division. 5. Young, G., Walkley, W., Taggart, D., Andrews, S. and Worrel, J., 199, Oil-Water Separation Using Hydroylones: An Experimental Searh for Optimum Dimensions. Amerian Filtration Soiety, Advanes in Filtration and Separation Tehnology, Vol.3, Conferene held in Baton Rouge, Louisiana.

13 SPE71538 OIL-WATER SEPARATION IN LIQUID-LIQUID HYDROCYCLONES (LLHC)-EXPERIMENT AND MODENLING 13 Table 1: Drag Coeffiient Constants Range b 1 b b 3 Re d < < Re d < < Re d < < Re d < Table : Effiieny Comparison with Present Study Test Droplet Size Distribution Pinlet P Temp. Q inlet Oilinlet Split Ratio Rejet Dia. Experim. Model (#) dmin (µm) d5(µm) dmax(µm) (psia) (psi) (ºF) (GPM) (%) (%) (mm) Effiien. Effiien Case D (mm) Table 3: Effiieny Comparison with Literature Data Flowrate (lpm) Oil Density (g/) Mean Drop Size (m) Experimental Underflow Purity (%) Model Underflow Purity (%) Table 4: Geometrial Parameters for Literature Data (Runs 9 to ) Case Design D(mm) a 1 a D L Ds Ls Di 8 IV 1º.75º.5D 3D D D.35D

14 14 C. Gomez, J. Caldentey, S. Wang, L. Gomez, R. Mohan, O. Shoham SPE71538 STORAGE SECTION PG3 MV OIL METERING SECTION PG4 MIXING UNIT DV MM CV V5 V6 TT V7 AIR V13 3-PHASE PG7 GRAVITY SEPARATOR V15 V14 OIL SKIMMER OIL TANK V4 V5 WATER TANK V11 PUMP PG5 PG6 MM MV3 CV3 V8 V9 TT3 V1 WATER METERING SECTION PUMP DV3 BY PASS LINE V18 V6 V1 V16 V17 WATER LINE V TEST V3 OIL LINE V1 SECTION V19 Figure 1: LLHC Hydrodynami Flow Behavior Figure 4: Shemati of Experimental LLHC Flow Loop Pressure Transduer Overflow Stream Pressure Transduer Thermometer Overflow Disharge Underflow Stream Aryli Hydroylone Steel MQ Hydroylone Isokineti Sampler System Mixing Loop Oil Stream Stati mixer Water Stream Speed Controller Gear Flow Meter Gear Pump Oil Tank Oil Stream Figure 5: Shemati of LLHC Test Setion Figure : Colman and Thew s Hydroylone Geometry Figure 3: LLHC Inlet Design Figure 6: Photograph of LLHC Test Setion