Flow Loop System Research Articles

Experimental study of wax deposition in pipeline – effect of inhibitor and spiral flow

Wax deposition is one of the main flow assurance problems in the oil industry. It can result in the restriction of crude oil flow in the pipeline, creating pressure abnormalities and causing an artificial blockage leading to a reduction or interruption in the production. Wax can precipitate as a solid phase on the pipe wall when its temperature (inlet coolant temperature) drops below the Wax Appearance Temperature (WAT). An experimental flow loop system was built in the lab to study the variation of wax deposition thickness under the single phase transport. A series of experiments were carried out at different flow rates (2.7 and 4.8 L/min) to study wax deposition and measure the wax thickness using four different techniques including direct technique pigging, pressure drop, heat transfer and liquid displacement-level detection (LD-LD). The effect of factors on wax formation such as inlet coolant temperature, inhibitor and spiral flow has been examined. The results show the wax inhibition percentage (WI)% was 40% and 45% at flow rate 2.7 and 4.8 L/min respectively of the inhibitor W802 (polyacrylate polymer (C16-C22)) at inlet coolant temperature 14 oC. The wax reduction percentage (WR) % was 65% and 73% at flow rate 2.7 and 4.8 L/min respectively of the spiral flow at inlet coolant temperature 14 oC. This percentage of inhibition will increased rapidly by increasing the inlet coolant temperature.

Evaluation of Performance of an Amine Based and an Imidazoline Based Gas Condensate Inhibitor Tested with a High Velocity Laboratory Test Rig

An amine based CO2 corrosion inhibitor and an imidazoline based CO2 corrosion inhibitor have been tested in a two-phase laboratory flow loop system under conditions of a gas condensate well in Austria. After a detailed description of the experimental setups, degradation rates of material API L-80 (UNS G41300) as function of flow velocity and inhibitor dosage are presented. Further, the influence of chloride addition on inhibitor performance has been investigated. All results are discussed with respect to critical inhibitor concentration to reach nearly 100 % inhibitor efficiency. Inhibitor A exhibits alkylamine as an active ingredient dissolved in ethylene glycol and different alcohols, and the effect of inhibitor B is based on imidazoline dissolved in different alcohols. Results demonstrate that the test rig delivers reasonable results with respect to inhibitor protection rates. Independent of superficial flow velocities (tested between 3 and 35 m/s), both inhibitors exhibit a good performance as long as dosed above their critical concentration. The critical concentration is clearly below 100 ppm to the liquid phase. The addition of chlorides affects the performance of the alkylamine based inhibitor significantly more than in case of the imidazoline.

Experimental Study on Hydrate Induction Time of Gas-Saturated Water-in-Oil Emulsion using a High-Pressure Flow Loop

Hydrate is one of the critical precipitates which have to be controlled for subsea flow assurance. The induction time of hydrate is therefore a significant parameter. However, there have been few studies on the induction time of the natural gas hydrate formation in a flow loop system. Consequently, a series of experiments were firstly performed, including water, natural gas and Diesel oil, on the hydrate induction time under various conditions such as the supercooling and supersaturation degree, water cut, anti-agglomerant dosage, etc. The experiments were conducted in a high-pressure hydrate flow loop newly constructed in the China University of Petroleum (Beijing), and dedicated to flow assurance studies. Then, based on previous research, this study puts forward a method for induction time, which is characterized by clear definition, convenient measurement and good generality. Furthermore, we investigated the influences of the experimental parameters and analyzed the experimental phenomena for the hydrate induction time in a flowing system.

Development of a Multi-modality Compatible Flow Loop System for the Functional Assessment of Mitral Valve Prostheses

We sought to build a robust pulsatile flow model permitting comparison of 3D Color Doppler and phase contrast magnetic resonance (PCMR) flow and orifice area measurements of prosthetic valve function that would provide an in vitro gold standard for evaluation of the accuracy of new imaging techniques. A multi-modality compatible, pulsatile linear actuation system, control software, and mock circulation loop was designed and created using non-ferromagnetic components, NI Labview, and rapid prototyping. The developed system’s ability to create pulsatile, controlled flow was assessed by examining peak diastolic flow, diastolic period, and diastolic flow volume (DFV) of 12 consecutive cardiac cycles at 3 different DFVs. Reproducibility of flow was tested by examining the systems ability to generate the same target DFV after draining and re-configuring the flow loop components. Furthermore, the system was evaluated by CMR and echocardiography to examine image quality, DFV quantification, and an initial functional assessment of prosthetic mitral valve (MV) orifice area by four different imaging methods. The system was able to reproducibly create prescribed flow volumes across 31 mm bioprosthetic and mechanical MV’s under a range of flow conditions. In vitro image quality for the identification of MV sewing ring, struts and leaflets was similar to clinical imaging quality for both echocardiographic and MRI methods. For the quantification of DFV, the PCMR method demonstrated an error range of 1.4–9.2% and a mean difference of 4 ± 2 mL/beat compared to the flowmeter reference standard. Across the three flow conditions the bioprosthetic MV diastolic flow area was statistically similar by MRI planimetry, phase contrast MRI planimetry, and 3D color Doppler planimetry methods (mean area 3.2 ± 0.5 cm2, ANOVA, p = NS), but the effective orifice area by 2D spectral Doppler (continuity) method was smaller (mean area 2.0 ± 0.3 cm2, ANOVA, p < 0.001). We describe the development and initial functional testing of a novel MRI-compatible flow loop system for comparison of multimodality imaging techniques to assess prosthetic valve function.

The Effect of Two Amine-Based Corrosion Inhibitors in Improving the Corrosion Resistance of Carbon Steel in Sea Water

This study investigates the effect of two amine-based corrosion inhibitors in reducing the corrosion rate (CR) of 1018 carbon steel in formulated sea water. For discussion purposes, the two inhibitors are named Inhibitor A (belongs to the alkyl pyridine benzyl chloride quaternary family of inhibitors) and Inhibitor B (belongs to the alkyl amines family of inhibitors). The two inhibitors are routinely considered for applications by Saudi Aramco, the world’s largest oil producing and processing company, for reducing its corrosion problems in carbon steel pipelines carrying oil and gas. The experimental apparatus was a circulating flow loop system inside an autoclave. The experimental work was performed at pH 8.2, 55 °C, and 1000 rpm. The inhibitors were evaluated at three different concentrations of 5, 10, and 15 ppm. The CR was determined using the weight loss method and electrochemical methods such potentiodynamic sweep and linear polarization resistance. The experimental results indicate that Inhibitor B reduced the CR more than that of Inhibitor A.

Evaluation of Two Different Inhibitor Testing Methods for High Superficial Flow Conditions

In future the pipe flow velocities in European gas fields will increase, but production rates are often limited by critical flow velocities of corrosion inhibitors especially at wet gas wells. A gas-liquid-ratio (GLR) of about 10,000 to 20,000 is very common in Europe, but there is no standardized testing procedure for inhibitors at such conditions. Therefore two different test methods, first, a jet impingement flow loop combination and, second, a pure flow loop system, were compared to find the best way of inhibitor testing at GLR of approximately 20,000. After a detailed description of the experimental setups, degradation rates of material API L-80 as function of flow velocity and inhibitor dosing for both investigated test Stems are presented. The long term goal is to determine limiting flow velocities for different inhibitors and to predict the inhibitor performance in real wet gas wells.

Electrochemical corrosion behavior of X52 and X60 steels in carbon dioxide containing saltwater solution

X52 and X60 high strength low alloy (HSLA) steels are widely used in the construction of petroleum pipelines. This paper discusses the corrosion resistance of X52 and X60 steels in CO2 containing saltwater at pH 4.4 and 50 ºC. A circulating flow loop system inside an autoclave was used for conducting the experimental work. The rotating impeller speed was 2000 rpm. The corrosion rate was monitored using in situ electrochemical methods such as potentiodynamic sweep, linear polarization resistance, and electrochemical impedance spectroscopy (EIS) methods. Results indicated that the corrosion rate of X60 steel is relatively higher than that of X52 steel.

Analysis of Trajectories for Targeting of Magnetic Nanoparticles in Blood Vessels

The technique of magnetic drug targeting deals with binding drugs or genetic material to superparamagnetic nanoparticles and accumulating these complexes via an external magnetic field in a target region. For a successful approach, it is necessary to know the required magnetic setup as well as the physical properties of the complexes. With the help of computational methods, the complex accumulation and behavior can be predicted. We present a model for vascular targeting with a full three-dimensional analysis of the magnetic and fluidic forces and a subsequent evaluation of the resulting trajectories of the complexes. These trajectories were calculated with respect to the physiological boundary conditions, the magnetic properties of both the external field and the particles as well as the hydrodynamics of the fluid. We paid special regard to modeling input parameters like flow velocity as well as the distribution functions of the hydrodynamic size and magnetic moment of the nanoparticle complexes. We are able to estimate the amount of complexes, as well as the spatial distribution of those complexes. Additionally, we examine the development of the trapping rate for multiple passages of the complexes and compare the influence of several input parameters. Finally, we provide experimental data of an ex vivo flow-loop system which serves as a model for large vessel targeting. In this model, we achieve a deposition of lentivirus/magnetic nanoparticle complexes in a murine aorta and compare our simulation with the experimental results gained by a non-heme-iron assay.

Radially symmetric endothelial cell replacement and lentiviral targeting in vessels by the use of magnetic nanoparticles (MNPs)

Endothelial cell damage often occurs in vascular disease such as atherosclerosis resulting in loss of vasoregulation and/or thrombosis. To restore endothelial function we have established novel methods to either combine site-specific endothelial cell positioning with lentiviral transduction in arteries or directly transduce the vascular endothelium in situ. Therefore, we have designed a special magnetic device to obtain a radially symmetric endothelial cell or lentivirus deposition on the vascular wall. Lentivirus is coupled to magnetic nanoparticles (MNPs) enabling the efficient transduction of endothelial cells by application of magnetic force. As a proof of concept we show that bovine pulmonary arterial endothelial cells (bPAECs) and human umbilical vein endothelial cells (HUVECs) are efficiently transduced with complexes of MNPs and lentiviral vectors carrying a GFP expression cassette. These cells can be positioned in a radially symmetric manner in an ex vivo flow-loop system. Moreover, this technique also allows for the direct lentiviral transduction of the murine endothelium in situ, which is proven by GFP expression in the vessel after 4–6 days in culture. We plan to use this approach in combination with the application of therapeutic genes e.g. the endothelial nitric oxide synthase (eNOS) to restore vascular endothelial function ex vivo and in vivo.

Kinetics of the remediation of Arsenic-contaminated groundwater using nanoscale magnetite particles

AbstractArsenate species are toxic compounds widely found as contaminants in industrial and metallurgical environments. Environmental health problems related to industrial waste streams and related drinking water contaminations can commonly occur. Around the world, from Bangladeshi water wells to Oklahoman metal plating sites, toxic levels of arsenic (As) leach into potable water. This paper describes a flow loop system that relies on magnetic nanoscale particles, iron oxide (nanorust), for the removal of these toxic metals. The nanorust particles have an extremely high surface area which allows for the rapid removal of these metal oxides. Perhaps even more importantly, nanorust (iron oxide) also has the unique advantage that it can be easily removed and re-concentrated using inexpensive low field magnetic (125 T) separation techniques. In this study we will present results on treating low levels of As in water with nano particles of mesh size at 50 nm and 26 nm. Determination of As concentrations below 100 ppb level was attained using an Inductively Coupled Plasma Mass Spectroscopy (ICP-MS) system and a continuous flow loop system.

Fibre length effect on fibre suspension flocculation and sheet formation

Fibre suspension flocculation was studied in a flow loop system, simulating the flow conditions in a modern paper machine headbox. The fibre suspensions after the headbox were accelerated by a secondary contraction, mimicking flow accelerations that may take place during forming. Fibre suspensions were studied using an optical detection method. Images were taken by a high speed video camera with transmitted infrared laser light pulse illumination separately before and after the secondary contraction. The mean fibre floc size was evaluated by power spectrum analysis in MID and CID respectively. A series of twelve pulp samples, four different commercial bleached softwood kraft pulps refined to three different levels, were used in the experiments. The fibre physical properties and formation number for paper sheets produced on a pilot paper machine with these pulp samples were characterised. Refining shortened the fibre length, thus decreased the fibre floc size in flowing suspensions and improved the formation in paper sheets. A series of mixtures at different ratios of bleached softwood and hardwood kraft pulps were also used in the experiments. The fibre physical properties of the mixtures were also characterised. The fibre length increases when increasing the ratio of softwood pulp in the mixture, thus fibre floc size in the suspension increases.

Fibre floc behaviour of softwood kraft pulp in flowing suspensions

Deformation of floes in flowing suspensions was studied in a flow loop system. A fibre suspension jet from a model headbox was further accelerated by a secondary contraction with a width reduction of 50%. The fibre suspension flocculation was studied using an optical detection method. For the suspension of bleached softwood kraft Pulp at a fibre concentration of 5 g/l, fibre floes were followed manually along the secondary contraction. About 115 of the floes were stretched to breakage in the contraction. The floes were stretched in MD whereas they were even more compressed in CD, so that the total floe area in the MD-CD plane decreased, indicating an increase of fibre concentration in the individual floes. This was confirmed by an increase of gray value of the floes in the light transmission images. Fibre floe orientation in MD increased when passing along the contraction. The manual evaluation confirmed the validity of the power spectrum analysis results. Increasing fibre concentration gave larger fibre floes. The floe area reduction in MD-CD plane during contraction passage increased when increasing fibre concentration, which might be due to an increase of mechanical forces in CD generated by the contracting walls, since less free water existed between the fibre floes at a higher fibre concentration. Increased absolute flow velocity had an insignificant effect on the fibre floes within the investigated range.

Some ways to decrease fibre suspension flocculation and improve sheet formation

Fibre suspension flocculation was studied in a flow loop system, simulating the flow conditions in a modern paper machine headbox. Fibre suspensions were studied using an optical detection method. ...

傾斜坑井掘削時の掘屑運搬挙動に関する実験的研究

Cuttings transport behavior in drilling directional wells was experimentally investigated using a once-through type large-scale flow loop apparatus, the Cuttings Transport Flow Loop System (CTFLS) in the Japan Oil, Gas and Metals National Corporation Kashiwazaki Test Field. The annular test section of the CTFLS is 9-m long and consists of a 5" ID transparent casing pipe and a 2.063" OD drillpipe. The inclination of the test section can be set at an angle from 0 to 90° in 15° increments. Drillpipe can be mounted either in concentric or eccentric mode.Experiments using two types of drilling mud, water and 0.15% PHPA solution, were conducted to focus on the effects of parameters such as hole inclination angle, drillpipe eccentricity, mud flow rate, mud rheology and rate of penetration (ROP). In the test procedure, mud was circulated and cuttings were fed into the test section both at constant rates, supposing a condition of drilling with constant ROP. Then, for predetermined mud flow rates, quantitative data in steady-state condition such as volumetric concentration of cuttings in the annulus, cuttings bed height and frictional pressure loss were measured. Critical flow rate determination based on a cuttings concentration criteria defined in this study was also presented, and optimum mud flow rate in actual field operation was discussed from a more practical point of view.

A flow loop system for study of fibre suspension flocculation

A flow loop system for study of fibre flocculation in Suspensions has been developed. The system is designed to simulate the flow conditions in a paper machine headbox. It is equipped with a radial distributor feeding a step diffuser pipe package, after which the flow is contracted in a 2-D nozzle. The flow system is also equipped with a secondary flow contraction, which is aimed for studies of fibre floc rheology. The conditions of the secondary contraction can be changed in order to generate different acceleration rates. The flow system is also equipped for dosage of retention/formation aids to Study the chemical effects oil fibre flocculation. The maximum flow velocity in the system is 16 m/s. Fibre Suspension flows were Studied using a high speed video camera and transmitted infra-red laser light pulse illumination. Images were taken either separately before and after or along the secondary contraction. Images of-fibre flocculation were evaluated by using power spectrum and wavelet transform analysis. By comparing the fibre flocculation before and after the secondary contraction, or by following the fibre floes during the secondary contraction, rheology information oil the fibre flocs call be obtained. By comparing the fibre flocculation information with and Without chemical additions, the effects of chemicals on fibre flocculation can also be studied.

Corrosion inhibitor studies in large flow loop at high temperature and high pressure

The performance of an imidazoline based inhibitor for carbon steel in a large diameter flow loop system with saltwater–oil two-phase flow under 90°C and 300 psi was studied by electrochemical impedance spectrum technique. It is found that the corrosion resistance is increased when the inhibitor is added in the solution. Experimental results show that the Warburg impedance coefficient, σ, and the charge transfer resistance, R t, increase with increase in exposure time until 8 h and then become stable. It is suggested that, before 8 h, the inhibitor film becomes more compact at longer exposure time. After 8 h, a stable inhibitor film is reached. From this work, it is also found that the values of σ and R t measured in the solution containing 100 ppm inhibitor is not significantly different from those in the solution containing 50 ppm. This fact implies that increase in inhibitor concentration from 50 to 100 ppm does not give a good performance of inhibitor and a high corrosion resistance.

EIS studies of a corrosion inhibitor behavior under multiphase flow conditions

EIS studies of an imidazoline-based inhibitor under multiphase flow conditions were conducted in a large diameter flow loop system. The Warburg diffusion parameter, b f =σω −1/2 was used to qualitatively analyze inhibitor films formed on the metal surface. Experimental results show that the inhibitor films become less porous with increase in exposure time and inhibitor concentration. Inhibition performance of the corrosion inhibitor is reduced in slug flow at high rate of turbulence and bubble impact. This study demonstrates that EIS is an effective technique to investigate the inhibition performance of corrosion inhibitors in turbulent flow conditions.

The kinetics and mechanism of Corynebacterium glutamicum aggregate breakup in bioreactors

Cultivation of bacteria requires high levels of agitation and aeration to satisfy the mass transfer requirements of the cells. Associated with these conditions are turbulent forces which may act on the surfaces of cells and be detrimental to their growth, metabolism and morphology. The kinetics and mechanism of hydrodynamic trauma has been investigated for the breakup of aggregates of Corynebacterium glutamicum ( ATCC 13032) in a stirred-tank reactor and a capillary flow loop system. The effect of forces associated with turbulent eddies in the impeller discharge zone of the stirred tank reactor has been compared with that of collapsing air bubbles at the air medium interface. A model is presented to describe the initial rate of aggregate breakup caused by fluid–aggregate interactions. It assumes that aggregate disruption is caused by the interaction of aggregates with similarly sized turbulent eddies. The extent of aggregate breakup is a function of the magnitude of the turbulent force as well as the total duration of the force event. The applicability of the model to animal cell systems has been investigated. Results showed that both the interaction of microbial cells with turbulent eddies in the viscous dissipation subrange in the impeller discharge zone, as well as with collapsing air bubbles at the air medium interface contributed to the total force acting on the cells.

In vivo hemodynamic evaluation based on transverse Doppler measurements of blood velocities and vessel diameter

We have developed a method for simultaneously measuring the blood flow velocity distributions along a line perpendicular to the vessel wall and the instantaneous diameter of the common carotid artery. Thus, the wall shear rates and shear rate distribution across the arterial lumen could be computed accurately. In this method, transverse Doppler technique is combined with ultrasonic A echo-mode, using only one single crystal transducer. In order to satisfy the requirements of high spatial and velocity resolutions, especially extending to a very low velocity range in the case of low signal-to-noise ratio, a combination scheme of 10-MHz operating frequency, sample volume tracking, 12-bit A/D, 512-point fast Fourier transform with 5-kHz sample rate, spectrum average, variable threshold for bandwidth estimation, smoothing of velocity curves, and hardware was carefully designed. The velocity distribution measurements based on transverse Doppler spectrums were also validated under the steady flow conditions using a flow loop system. Results from this study show this ultrasonic system to be capable of measuring the shear rates at wall accurately and shear rate distributions across the common carotid arterial lumen.

In vitro evaluation of electrostatic endothelial cell transplantation onto 4 mm interior diameter expanded polytetrafluoroethylene grafts

Purpose: To perform an in vitro evaluation of electrostatic endothelial cell transplantation of human umbilical vein endothelial cells (HUVEC) onto segments of 4 mm internal diameter expanded polytetrafluoroethylene (ePTFE) vascular prostheses. Methods: This evaluation consisted of exposing vascular graft segments that had been subjected to either electrostatic or gravitation transplantation with HUVEC to a physiologic shear stress (15 dynes/cm 2) under steady flow conditions within a flow loop system. Biochemical assays were performed on freshly transplanted grafts by means of radioimmunoassay for prostacyclin and thromboxane A 2. Results: There was a 30% loss of HUVEC after 30 minutes of shear stress exposure from the grafts subjected to gravitational transplantation with no additional significant (α = 0.05) loss after 120 minutes. Grafts subjected to electrostatic transplantation had no significant (α = 0.05) loss of HUVEC during exposure to physiologic shear stress. Furthermore, after 120 minutes of shear-stress exposure, the grafts subjected to electrostatic transplantation (78,420 ± 6274 HUVEC/cm 2) retained 2.3 times more HUVEC than the counterparts subjected to gravitational transplantation (34,427 ± 4637 HUVEC/cm 2). The biochemical assay results indicated no significant (α = 0.05) production of prostacyclin or thromboxane A 2 regardless of the method of cell transplantation. Conclusions: (1) The electrostatic transplantation technique was superior to the gravitational transplantation technique in terms of cellular retention when the ePTFE grafts were exposed to physiologic shear stress. (2) Production of prostacyclin and thromboxane A 2 did not differ between transplanted HUVEC subjected to gravitational or electrostatic procedures. (J Vasc Surg 1998;27:504-11.)