In this paper we present a novel approach to designing sensors and instrumentation for monitoring and controlling multiphase processes. Our concept is based on using distributed sensor arrays, embedded within the vital plant components and thus forming smart structures . Distributed information obtained from such devices, coupled with appropriate data processing, could improve our understanding of the nature of multiphase processes and hence improve plant operation. We discuss the requirements for such sensors and, in the experimental part of this paper, present a short case study, conducted at UMIST Pilot Plant facility, to highlight the benefits of using smart sensing techniques in a process environment. We hope that this paper will open a general discussion on sensing multiphase flows.

Nahcolite is a naturally occurring sodium bicarbonate mineral found in subsurface formations. American Soda LLP conducted field tests to prove that nahcolite can be deep mined using low-cost conventional solution mining method. The process involved the injection of hot, high pressure water down wells into a nahcolite deposit about 2,600 feet below the surface where the mineral is dissolved and brought to the surface for recovery. The monitoring and optimization of recovery efficiency based on scores of upstream process parameters, such as water injection rate, required the monitoring of produced liquid density. This was done initially with a mass meter located immediately downstream of the well head. Co-production of small amounts of gas, mainly methane and carbon dioxide, entrained in the liquid phase prevented the accurate measurement of the solution density using a Coriolis meter technology. Premier Instruments provided a remedy with a gas liquid cylindrical cyclone (GLCC © 1 ) separator properly sized and engineered for the process requirements. A gas control valve with liquid level feedback was used to eliminate the entrained gas in the liquid phase. This strategy proved to be functional which allowed American Soda to proceed with the field development. Today, 26 production wells employ the GLCC separator at each production well.

INA-Naftaplin has been utilizing the LO-CAT ® process in Croatia for protection of ambient air against H 2 S pollution at its Gas Treatment Plant Molve III already for seven years. This separation unit, incorporated into the gas treatment plant has been erected exclusively for the protection of ambient air against harmful effect of H 2 S. The unit is treating H 2 S+CO 2 , which is being removed from natural gas by an upstream amine process, under conditions of low H 2 S content and low pressure of gas. Catalytic oxidation is being used to convert H 2 S to elementary sulfur, and the emission concentration was decreased from 580 ppm to less than 30 ppm. The practice revealed a series of delicate situations: plugging of internals, solution filtering and achievement of required 60 wt% sulfur concentration, disposal of produced sulfur sludge and others. The Institute for Medical Research Zagreb has performed the ambient air quality monitoring, within the scope of its contract for annual base monitoring. H 2 S imission values were under 5 μg/m3. The continuous control of working area is achieved by twenty-four H 2 S sensors, and results obtained to this date have always been below allowable limits. The practical experience has revealed that the LO-CAT ® desulfurization unit has fulfiled its purpose and existing environmental criteria till 1997, along with significant cost, primarily for power and chemicals. The actual Croatian Directive on TLV of pollutants in the waste gas requires H 2 S concentration of 3.5 ppmv max. and RSH concentration of 20 mg/m 3 max. Now the GTP Molve and Ethane Recovery Plant have emission of H 2 S and mercaptane above the permissible limit value, which have to be solved until the year 2004. To meet the strict legal requirements, certain upgrading is to be undertaken. This capital investment requires a large financial expenditure of up to 5 million USD, and up to 1 million USD/year for operating cost for both plants. For process improvement a continuous monitoring system has to be solved also. In that respect, measuring of H 2 S+RSH emission is in accordance to ASTM D-4084-82 and ASTM D-23 85-81 methods. Periodical control by gas tube detector system could contribute to the most reliable and efficient monitoring system of the two most important natural gas plants in Croatia.

Problems of indentation of orthotropic laminated beams due to flat punches arc solved. Exact solution methods for a subsidiary problem are developed first for both the simply-supported and clamped-ended cases. A numerical iteration algorithm is then employed to assess the possible separation and the real contact area and the contact stresses for a given punch width and a beam span. The contact stresses and separation results for the beams of a typical span reveal various contact conditions that depend only upon the punch width but not the magnitude of the applied load. For a symmetric lamination of the beam, a wide range of punch widths and beam spans are implemented to detect the critical punch widths rendering the onset of separation between the punch and the beam and to establish the threshold curve for the critical aspect ratio of the beam versus the relative punch width. The effects of both the end support condition and slacking sequence of the beam upon the contact and separation scenarios as well as the threshold behavior are thoroughly evaluated.

The use of Gas-Liquid Cylindrical Cyclone (GLCC © ) separators for gas-liquid separation is a new technology for oil and gas industry. Consequently, it is important to understand the flow behavior in the GLCC © and effect of different geometrical configurations to enhance separation. The main objective of this study is to address the effect of different inlet configurations on flow behavior in the GLCC © by measuring velocity components and turbulent kinetic energy inside the GLCC © using a Laser Doppler Velocimeter (LDV). Three different inlet configurations are constructed, namely: one inclined inlet, two inclined inlets and a gradually reduced inlet nozzle. Axial and tangential velocities and turbulent intensities across the GLCC © diameter were measured at 24 different axial locations (12.5” to 35.4” below the inlet) for each inlet configuration. Flow rates of 72 and 10 gpm are selected to investigate the effect of flowrate (Reynolds number) on the flow behavior. Measurements are used to create color contour plots of axial and tangential velocity and turbulent kinetic energy. Color contour maps revealed details of the flow behavior.

Accurate prediction of slug length distribution and the maximum slug length in a hilly terrain pipeline is crucial for designing downstream separation facilities. A hilly terrain pipeline consists of interconnected uphill and downhill pipe sections, where slugs can dissipate in the downhill sections and grow in the uphill sections. Furthermore, new slugs can be generated at the dips (bottom elbows) and dissipate at the top elbows. Although existing steady-state models are capable of predicting the average slug length for pressure drop calculations and pipeline design, they are incapable of predicting detailed flow characteristics such as the maximum slug length expected at the exit of a hilly terrain pipeline. A transient slug tracking model based on a quasi-equilibrium formulation was developed to track the front and back of each individual slug, from which individual slug lengths are calculated. The model was verified with large-scale two-phase flow hilly terrain experimental data acquired at the Tulsa University Fluid Flow Projects (TUFFP). The results show a fairly accurate match between the model predictions and experimental data.

The main goal of the present work is to establish the tools of the analysis and performance prediction of an axial pump stage under two-phase flow presence of liquid and gas. This knowledge is very important for different applications, for example in the oil industry. The transport of two-phase flow (oil and gas) that comes from the well implies the utilization of separation and treatment facilities before they are pumping. It means that a lot of economical resources are involved in this kind of industrial operation. Therefore, depending on the function optimization of this type of two-phase pumps, it would permit the substitution of the traditional expensive facilities in addition with energy cost savings. In order to predict the fluid dynamics characteristics of an axial pump stage under two-phase flow conditions and in view to improve its performance, the present research will describe a multi-fluid model in order to solve the momentum equations (Navier-Stokes) coupled with the continuity equation. Here, we will take into account the viscosity of the liquid phase and the compressibility of the gas phase, using the CFD simulator: CFX 4.0. Finally, an experimental facility was designed and built to test one axial pump of two stages. Therefore, experimental data is shown in order to validate the previous numerical results obtained.

The twin-screw multiphase pump has been studied as an alternative system to substitute the conventional one (fluid separation, liquid pumping and gas compression) in petroleum boosting. By “pumping” simultaneously gas and liquid, the multiphase pump could reduce production costs in deepwater activities. This paper presents a thermodynamic model of a twin-screw multiphase pump to determine performance parameters such as: absorbed power, discharge conditions and efficiency. To overcome problems with the complex flow field inside of this novel equipment, the multiphase flow was divided into a sequence of simpler processes. Such approach helps determine energy and mass balances and enables the use of a process simulator ( Hysys.Process v2.1 ) to construct the model. The model prediction when compared to the literature show that the assumption of a smooth turbulent flow, considering the pressure loss in the entrance and discharge of the gap, fits better the phenomena than the turbulent flow when calculating the flow through the gaps. In addition, the comparison for absorbed power indicates that the assumption of gaps filled only with liquid is not valid under all operation conditions.

First oil production from a deep-water oil field is to be achieved by the installation of an Initial Development System (IDS). Well testing is required for field development and reservoir management. The well testing system requires high accuracy oil and water rates to provide the data needed for decision analysis in ongoing drilling programs. The well testing system must also be integrated with other platform operations such as well clean up after drilling. The concept of a certain type of multiphase meter in a feedback control loop with conventional separation technology for process control is simulated to extend the capabilities of both technologies. The principle of GVF control as a supplementary to level control system has been developed for performance enhancement of oil field well testing. Concepts demonstrated here can also be easily applied as retro-fits to existing separation facilities which show accuracy or upset problems because of the simplicity and compact size of the additional multiphase meter component and non-disruptive supplementary integration with existing level control systems.

The feasibility of using Liquid-Liquid Cylindrical Cyclone (LLCC © ) as a free water knockout device for bulk separation of oil-water mixtures in the field strongly depends on the implementation of control systems due to its compactness, less residence time and possible inlet flow variations. In this investigation, the LLCC control dynamics have been studied extensively both theoretically and experimentally. A linear model has been developed for the first time for LLCC separators equipped with underflow watercut control, which enables simulation of the system dynamic behavior. A unique “direct” control strategy is developed and implemented, capable of obtaining clear water in the underflow line and maintaining maximum underflow rate. Dedicated control system simulations are conducted using Matlab/Simulink ® software to simulate the real system dynamic behavior. Detailed experimental investigations are conducted to evaluate the system sensitivity and dynamic behavior of the proposed control strategy. The results demonstrate that the proposed control system is capable of controlling the underflow watercut around its set point by obtaining maximum free-water knockout for a wide range of flow conditions. (inlet water concentration of 40% and an inlet mixture velocity of 1.5 m/s).