Liquid-liquid Hydrocyclone Research Articles

Numerical Investigation on Oil/Water Separation by Compact Nozzle- Axial Hydrocyclone

The separation of fluid-fluid mixtures is a major issue in various sectors. The liquid-liquid hydro-cyclone has a wide range of applications in various sectors due to its great efficiency in separating fluid mixtures, ease of installation, and low cost. In crude oil production, high water is consumed following the degrading of production quality, high processing costs, costs, and environmental impacts. Axial hydro cyclone is a tool for Downhole Oil/Water Separation (DOWS) in the petroleum production industry, but it has limitations. The main purpose of this work is to simulate the effect of compacting the conventional inline hydro cyclone with a converging-diverging nozzle on the oil/water dynamic flow and the separation process to resolve the high water cut problem. This study presents a three-dimensional simulation to compute fluid dynamics using the mixture multiphase and SST k-omega turbulence models for Reynolds numbers less than 66000. The operational flow variables are a mixture: flow rate (14, 28, and 56 m3/h) and oil/water ratio (15/85, 25/75, 30/70, and 35/65). Results indicate an enhancement in the axial and tangential velocity components by 15% and 50%, respectively, for the proposed design compared with the conventional cyclone. The oil separation efficiency for the new design is 89%, while for the conventional cyclone is 60%.

Assessment of turbulence models for single phase CFD computations of a liquid-liquid hydrocyclone using OpenFOAM

ABSTRACT Hydrocyclones are widely used in industry and CFD has been used to compute them. Reynolds stress turbulence models (RSM), which are computationally costly and oftentimes hard to converge, are often recommended in these computations. The present work has selected a liquid-liquid separation hydrocyclone for which single-phase experimental tangential and axial velocity profiles are available. CFD has been employed to test simpler turbulence models than the RSM and results have been compared with experimental data. The turbulence models assessed in the present work were: standard k-ε, standard k-ε with a curvature correction term, RNG k-ε, realizable k-ε, k-ω, SST, a two-time-scale linear eddy viscosity model, nonlinear quadratic and cubic k-ε eddy viscosity models and the Gibson and Launder and LRR Reynolds stress models. Computations have been carried out with OpenFOAM 2.2.2. Results using the Gibson and Launder turbulence model have been compared to some obtained with Ansys Fluent and these were in agreement. Results have shown that all turbulence models, apart from the RSM, returned basically the same tangential velocity profiles as the standard model. All turbulence models have failed in predicting axial velocity. Assessment of the Reynolds stresses has indicated that the internal flow field in hydrocyclones might be shear dominant and that the Reynolds shear stress component is the most relevant to correctly predict tangential velocity. Geometric proportions of hydrocyclones may affect significantly the intensity of rotational and streamline curvature effects. Two-equation eddy-viscosity models are likely to be able to attend such condition, since appropriate levels of eddy viscosity are predicted at free and forced vortexes regions, however further investigation is still needed.

Performance of liquid–liquid hydrocyclone (LLHC) for treating produced water from surfactant flooding produced water

Purpose The purpose of this study is to investigate the performance of the fabricated liquid–liquid hydrocyclone (LLHC) with dimensions similar to those of one of the Malaysian oilfields with the presence of an anionic surfactant, S672. The effect of salinity and initial oil concentration were also investigated following the actual range concentration. Design/methodology/approach The current control system’s pressure drop ratio (PDR) does not necessarily lead to an efficient LLHC. Therefore, rather than using the PDR, the efficiency of the LLHC was analyzed by comparing the concentration of oil in the effluents with the concentration of oil at the feed of the LLHC. An LLHC test rig was developed at Centre of Enhanced Oil Recovery, Universiti Teknologi PETRONAS. Emulsions were prepared by mixing the brines, S672 and oil by using Ultra Turrax ultrasonic mixer. The emulsion was pumped into the LLHC at different feed flowrate and split ratio. The brines concentration, initial oil concentration and S672 concentration were also varied in this study. Samples were taken at the underflow of the LLHC and the oil in water concentration analysis was done for the samples using TD-500D equipment. Findings It was found that the efficiency of oil removal decreased with an increase in S672 concentration but increased with the increase in salinity and initial oil concentration. Originality/value The optimum feed flowrate for the LLHC of 45 mm diameter and length of 1,125 mm with the presence of S672 surfactant was found to be 40 L/min with a split ratio of 14%. This study can be used as a guidance for future optimization of the LLHC in the presence of the surfactant.

A NEW COMPUTATIONAL FLUID DYNAMICS STUDY OF A LIQUID-LIQUID HYDROCYCLONE IN THE TWO PHASE CASE FOR SEPARATION OF OIL DROPLETS AND WATER

Abstract A liquid-liquid hydrocyclone, so-called de-oiling equipment, was investigated for separation of oil droplets and wastewater in an Iranian petroleum unit. To generate the geometry and the mesh of the hydrocyclone Gambit software was used. Afterwards, by taking advantage of the Euler-Lagrangian principle, the governing equations covering the motion of fluid and that of particles in the hydrocyclone were solved. Initially, it was shown that the outcomes of CFD are in agreement with experimental data, and then 15 hydrocyclones with different overflow diameters, overflow lengths and input velocities were employed for more detailed analyses. The separation process through a hydrocyclone is counted as an economical process when ther is not only a low pressure drop inside the hydrocyclone, but also a high separation efficiency. As a result, regarding the mentioned criteria, the optimum hydrocyclone, whereby the highest performance of the hydrocyclone is exploited, was obtained by applying the 15 sets of CFD data to a Neural Network (NN) and then by optimizing the function generated by the NN by means of a Genetic Algorithm (GA). The innovation of this research work is the three-phase modeling.

Predicting the Efficiency of the Oil Removal From Surfactant and Polymer Produced Water by Using Liquid–Liquid Hydrocyclone: Comparison of Prediction Abilities Between Response Surface Methodology and Adaptive Neuro-Fuzzy Inference System

The present study developed, evaluated and compared the prediction and simulating efficiency of both, the response surface methodology (RSM) and adaptive neuro-fuzzy inference system (ANFIS) approaches for oil removal using a liquid-liquid hydrocyclone (LLHC) from surfactant and polymer (SP) produced water. Six parameters were involved in the process: the surfactant concentration, polymer concentration, salinity, initial oil concentration, feed flowrate and split ratio. For RSM, D-optimal design was used, while the ANFIS model was developed in term of this process with the Gaussian membership function. All models were compared statistically based on the training and testing data set by the coefficient of determination (R 2 ), root-mean-square error (RMSE), average absolute percentage error (AAPE), standard deviation (STD), minimum error, and maximum error. The R 2 for RSM and the ANFIS model for the testing set were of 0.972 and 0.999, respectively. Both models made good predictions. Trend analysis has been done to confirm the applicability of the models. From the results, it shows that the ANFIS model was more precise compared to the RSM model, which proves that the ANFIS is a powerful tool for modelling and optimizing the efficiency of the oil removal from the LLHC in the presence of SP.

Numerical studies on the separation performance of liquid- liquid Hydrocyclone for higher water-cut wells

Liquid-liquid hydrocyclones have nowadays become very useful in the oil industry because of their numerous applications. They can be installed downhole in the case of a well that produces higher water-oil ratios. The design of a liquid-liquid hydrocyclone for such a task is critical and every geometric part of the hydrocyclone has a part to play as far as separation is concerned. This work, through validated numerical technique, investigated the liquid-liquid hydrocyclone performance for the cases of single-inlet and dual-inlets, with different upper cylindrical lengths, specifically, 30mm and 60mm.It was observed that the hydrocyclones with the 30mm upper cylindrical section perform better than the ones with 60 mm upper cylindrical section. It was again noted that, even though higher number of tangential inlets increases the swirl intensity, they have the tendency to break up the oil droplets within the hydrocyclone because of increasing shear and jet flow interaction.

Experimental Study on Downhole Oil-water Separation Hydrocyclone

In the process of downhole oil-water separation, the traditional liquid-liquid separation hydrocyclone (LLSH) is used in conjunction with screw pumps, which makes the hydrocyclone rotating around its own axis. The rotation of wall of hydrocyclone affects its internal flow characteristics and separation properties directly. The orthogonal experiment of the downhole oil-water separation hydrocyclone (DOWSH) is designed to analyze the effect of flowrate, rotating speed and split ratio on separation efficiency and pressure drop, The primary and secondary factors of operation parameters have been studied, and the optimum condition and reasonable working range of DOWSH have been obtained. It provides reliable basis for process of practical application of DOWSH􀀁so as to guide the production.

The Viability of Composite Membrane in Treating Produced Water from Oil and Gas Field in Malaysia

As the oil and gas industry grows rapidly worldwide over the years, the production of produced water is also increasing. Million barrels of water are produced each day worldwide. This situation has become a major problem and a to the environment and ecosystem. Produced water contains many constituents such as dispersed oil, metals and chemicals that have a high toxicity and very harmful to the marine life. Therefore, it must be treated prior disposal to the environment or reinjection into the well and formation. There are many methods of treatments such as liquid-liquid hydrocyclone, floatation technology and membrane technology. Membrane technology is quite a new technology for the treatment of produced water in oil and gas industry. This paper is focused on the viability of using composite membranes which are Polysulfone (PSU), Polysulfone-bentonite (PSU-bentonite), PSU-PVP (Polysulfone-Poly vinyl pyrrolidone) and Polysulfone-Poly vinyl pyrrolidone-bentonite (PSU-PVP-bentonite) for the treatment of produced water. The objectives of this study are; 1) to characterize the produced water, 2) to prepare and cast the composite membrane and 3) to investigate the membrane performance in treating the produced water. The performance of the composite membrane were tested by using the produced water as wastewater feed and the best composite membrane is determined by the membrane performance. In the membrane preparation process, a method have been used namely phase inversion method. This research found that technically composite membrane have a good potential to be used in treating produced water from Malaysian oil and gas field. Thus, further technical and economic study on this treatment method is suggested for industrial scale application.

Theoretical background and the flow fields in downhole liquid-liquid hydrocyclone (LLHC)

Hydrocyclone system for downhole oil-water separation provides an effective technique of enhancing the economic viability of higher water-cut wells while at the same time reducing the risk of environmental pollution. This paper describes the hydrodynamics of the liquid-liquid hydrocyclones and the flow fields within it are paramount for achieving successful separation process. Some of the important hydrodynamic flow phenomenon within the liquid-liquid hydrocyclone and how they influence the separation efficiency of water/oil was analyzed through analytical solution. The properties of the liquids were based on Bayan offshore field measured properties. The results indicated that there are two swirling zones separated by stagnant flow field. The inner is the light liquid zone, while the outer is the heavy liquid zone.

Numerical Simulation of Oil-water Hydrocyclone Using Reynolds-Stress Model for Eulerian Multiphase Flows

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Integration Of The Canmet Hydrocyclone In A Conventional Heavy Oil Treatment Facility

Abstract The CANMET hydrocyclone is a high-performance separation unit developed to de-oil a variety of oily fluids, including high water-cut wellhead production. A large number of heavy oil wellhead production streams in western Canada and elsewhere contain in excess of 70% water by volume. Integration of the CANMET hydrocyclone offers a technically and economically advantageous alternative to conventional gravity-based separation units for the treatment of these production fluids. Hydrocyclones separate fluids of differing densities by means of strong centrifugal forces generated by a high-speed vortex flow within the unit. The CANMET hydrocyclone combines a number of unique design features that result in enhanced performance in a variety of applications compared to conventional designs. Field testing has shown that oil production rates can be increased by the integration of hydrocyclone technology in wellhead production treatment schemes. Hydrocyclones are compact, have very short retention times, and reduce the processing load on downstream gravity-based separators. Important energy consumption and environmental benefits are also gained through reduced heating requirements. Hydrocyclone Development In the 1990s, CANMET began development work on an advanced hydrocyclone design for treating difficult-to-separate oily fluids encountered by the heavy oil industry in western Canada. A new design, called the CANMET hydrocyclone, was developed with the collaboration of Professor M. Thew of the University of Bradford, U.K. (formerly of University of Southampton), the original inventor of modern liquid-liquid hydrocyclones. Successful field testing of the CANMET hydrocyclone led to commercial installations in western Canada, and hydrocyclones are now recognized as one of the most efficient technologies for oily water separation. The CANMET hydrocyclone was patented in 1999 and is being marketed under separate licenses by Universal Industries Corporation and Krebs International. Separation in a Hydrocyclone A liquid-liquid hydrocyclone, as illustrated schematically in Figure 1, consists of an involute, a tapered body, and outlets for overflow and underflow. The stream of feed fluid under pressure enters the hydrocyclone tangentially and forms a high-speed vortex capable of producing centrifugal accelerations greater than 1,000 times that due to gravity. The separation forces in a hydrocyclone are proportional to the densities of the different components of the feed fluid. Solids and water, having higher densities than the oil phase, are forced toward the outer wall of the unit, while the less dense oil component is displaced toward the centre axis. The tapered body of the hydrocyclone confines the vortex flow to a decreasing radius, thus maintaining or increasing the radial velocity and, in turn, the centrifugal forces generated. The diameter of the overflow orifice regulates the rate at which overflow escapes and the purity of the oil stream. The overflow and underflow outlets can also be governed by means of pressure transducers to control the flow rate of each component stream. Water and solids exit the hydrocyclone through the underflow outlet at the end of the unit. Factors Affecting Hydrocyclone Performance The effectiveness of hydrocyclones depends on several factors. First, the size of the suspended oil droplets can limit separation efficiency.

Numerical simulation of strongly swirling turbulent flows in a liquid-liquid hydrocyclone using the Reynolds stress transport equation model

The Reynolds stress transport equation model (DSM) is used to predict the strongly swirling turbulent flows in a liquid-liquid hydrocyclone, and the predictions are compared with LDV measurements. Predictions properly give the flow behavior observed in experiments, such as the Rankinevortex structure and double peaks near the inlet region in tangential velocity profile, the downward flow near the wall and upward flow near the core in axial velocity profiles. In the inlet or upstream region of the hydrocyclone, the reverse flow near the axis is well predicted, but in the region with smaller cone angle and cylindrical section, there are some discrepancies between the model predictions and the LDV measurements. Predictions show that the pressure is small in the near-axis region and increases to the maximum near the wall. Both predictions and measurements indicate that the turbulence in hydrocyclones is inhomogeneous and anisotropic.

An empirical model for a hydrocyclone: Reject rate versus orifice size and pressure ratio

The parameters that affect the reject ratio of a 35 mm liquid-liquid hydrocyclone in test runs that use water alone to obtain flow data-parameters such as inlet pressure, pressure differential ratio, inlet flow rate and reject orifice diameter are explored. Study of the observed relationships indicates that of the parameters listed, only reject orifice diameter and pressure differential ratio have a direct correlation to a liquid-liquid hydrocyclone's reject ratio performance. An equation is presented that uses these two parameters to model the reject ratio performance of several reject orifice sizes. The most accurate model presented uses pressure differential ratio as the parameter for a basic equation form, which has a different set of coefficients for each reject orifice size. The practical application of the resulting relationships is discussed and the analysis presented graphically.

BASS STRAIT WATER HANDLING DEVELOPMENTS

Esso Australia Ltd operates, on behalf of Esso/BHP, a crude oil and natural gas producing and processing facility in the Gippsland Basin, Victoria. Saline formation water produced with the oil is treated and discharged overboard from offshore platforms wherever possible to limit the volume of saline water in the pipeline system and avoid onshore disposal of saline water. Esso has developed oily water treatment and continuous oil-in- water monitoring beyond conventional technology and operates within stringent overboard water discharge regulations. Initial oily water treating installations were Cross Flow Interceptors, a corrugated plate gravity separator. Unsatisfactory performance prompted investigations leading to development of the Dissolved Gas Flotation unit using evolved gas to lift oil droplets to the surface. These units operate successfully offshore today. The most recent developments have been associated with a liquid-liquid hydrocyclone trade named 'Vortoil'. This has been tested offshore with an 'Purometer' continuous oil-in-water monitor. The Vortoil and Purometer have both performed favourably and proven a compact, low cost combination for future water treating installations.