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Control valve stiction is prevalent in the process industry, leading to oscillations in process variables and degrading unit performance. Stiction is usually repaired during scheduled plant maintenance, but until then, compensation methods are required to reduce oscillations. This study presents a novel approach to address this problem by identifying control valve and process models and optimizing control parameters. The method combines a stiction model, a process model, and a controller to achieve optimal control with stiction. Additionally, the method incorporates a controller output filter and considers undershooting during the step response for control performance assessment. The proposed method is designed to handle different types of valve stiction models, providing a versatile solution. The results show that our method significantly improves the control loop performance of all valves tested.

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Patients with COVID-19 are not eligible for any therapy. Patients who have had respiratory failure and are unable to provide oxygen via noninvasive means obtain supportive care in ICUs. Since the onset of the outbreak, every sick COVID-19 patient has received oxygen via a mechanical ventilator. This study describes and simulates the transient stability of systems in an automated pressure regulator utilizing a single-acting cylinder in a clinical ventilator. These components include horizontal controllers, control devices, connecting tubes, and PID for electro-pneumatic control. Increased system stability and nonlinearity in electro-pneumatic actuator systems are accomplished by the implementation of PID. The redesigned PID control architecture was enhanced with alternative acceleration feedback through the close loop with an integral control method to get the system stable. This introduces the standard value N from the outside vicious circle and applies a form control law to integrate all reference control supply through into the gadget. Even as proportional gain (Kp) gets increased, the controller output would increase proportionately while maintaining the exact degree of accuracy. A derivative term boosts the ability of the Kd regulator to ''detect'' malfunctions. The integral term of the Ki controller minimizes its set point distortion. The system was updated to make it feasible for transferrable knowledge and competencies by incorporating real industrial components. The completed fluid control system was simulated through FluidSIM, which is frequently helpful for educational purposes.

Industrial Control Systems (ICS) and SCADA (Supervisory Control and Data Acquisition) systems play a critical role in the management and regulation of critical infrastructure. SCADA systems brings us closer to the real-time application world. All process and equipment control capability is typically provided by a Distributed Control System (DCS) in industries such as power stations, agricultural systems, chemical and water treatment plants. Instead of control through DCS, this paper proposes a SCADA and PLC (Programmable Logic Controller) system to control the ratio control division and the assembly line division inside the chemical plant. A specific design and implementation method for development of SCADA/PLC based real time ratio control and automated assembly line system in a chemical plant is introduced. The assembly line division is further divided into sorting stage, filling stage and the auxiliary stage, which includes the capping unit, labelling unit and then the storage. In the ratio control division, we have defined the levels inside the mixer and ratio of the raw materials through human machine interface (HMI) panel. The ratio of raw materials is kept constant on the basis of flow rates of wild stream and manipulated stream. There is a flexibility in defining new levels and the ratios of the raw materials inside the mixer. But here we taken the predefined levels (low, medium, high) and ratios (3:4, 2:1, 2:5). Control valves are used for regulating the flow of the compositions. In the assembly line division, the containers are sorted on the basis of size and type of material used i.e., big sized metallic containers and small sized non-metallic containers by inductive and capacitive proximity sensors. All the processes are facilitated with laser beam type or reflective type sensors on the conveyor system. Building a highly stable and dependable PLC/SCADA system instead of Distributed Control System is required to achieve automatic management and control of chemical industry processes to reduce waste manpower and physical resources, as well as to improve worker safety. [ABSTRACT FROM AUTHOR]

Reducing the occurrence of pipe bursts, reducing leakage, and reducing energy consumption are the three main goals in implementing pressure control programs in water distribution networks. Service pressure regulation strategy is an evolved approach that encompasses all goals of pressure management. This paper has investigated this approach in a rural network with hydraulic complexities as a case study so that some parts of the network have excess pressure and other low pressure. A computer code based on the method of characteristics (MOC) has been developed for network hydraulic analysis. The generated code analyzes unsteady flow, pressure-driven demand analysis, and dynamic adjustment of pressure control valves based on the target node. Also, the experimental results of a laboratory network have been applied to validate and calibrate the numerical simulation. In addition, by measuring the flow rate and pressure of the network and the results of the minimum night flow method, three consumption patterns were used to generate pulsed nodal demands. Studies show that creating pressure-management areas by hydraulic analysis by MOC will determine the best control strategies. The mean pressure decreased 54% by applying this strategy. Furthermore, the average fluctuations of pressure reduced from 9.7 meters to 3.5 meters. HIGHLIGHTS Hydraulic analysis was performed by the MOC based on pulse demand.; The leakage pattern, along with two other consumption patterns, was used to distribute the demand in the nodes.; A laboratory network was used for the calibration of real network parameters.; The service pressure regulation led to a 64% reduction in pressure fluctuations.; RTC-PRV, FO-PRV, and VSD-pump were proposed to control rural network pressure.;

This work proposes a model predictive control (MPC) strategy for pressure management and leakage reduction in a water distribution system (WDS). Unlike most of the reported models that mainly consider EPANET-based models, the proposed method considers its dynamic representation given by ordinary differential equations. The proposed MPC uses a pressure-reducing valve (PRV) as a control element to regulate the pressure in the WDS to track the demand. The control scheme proposes a strategy to manage the high nonlinearity of the PRV and takes into account the demand profile throughout the day as well as the leaks that occur in the pipeline. The estimates of magnitude and location of the leak are provided by an Extended Kalman Filter from previous work and with the aid of a rule-based set point manager reduces the fluid loss in the event of a leak. Different scenarios are studied to illustrate the effectiveness of the proposed control system, achieving an approximate reduction of up to 5% of water losses, demonstrating robustness in the case of uncertainty in the leak location estimate. [ABSTRACT FROM AUTHOR]

This paper presents the concept of reconstruction of the existing coal-fired combined heat and power plant to comply with new European environmental policies. The existing coal-fired boiler will be replaced by two new dual pressure heat recovery steam generators, which will utilize the exhaust gas heat from two new gas turbines. The steam from the heat recovery steam generators will be fed to the existing steam turbine. After the reconstruction, the nominal turbine inlet steam mass-flow of 40 kg/s will be reduced to 30 kg/s. During periods of low heat demand, only one gas turbine and one heat recovery steam generator will be in operation and the live steam mass-flow may drop even to 12 kg/s. Prior to the reconstruction, dedicated tests of the existing steam turbine were carried out using the steam from the existing coal-fired boiler. The goal of the test was to verify the viability of operation with such an extremely low mass-flow. The results of tests show that such operation is possible but inefficient from a power generation point of view. Besides this, the turbine control algorithm needs to be accommodated to this extreme operating regime and additional measures like displacement of the extraction points and steam cooling will be required to control the temperature of the steam extractions. The novelty of this paper is using real pre-reconstruction process data for the assessment of feasibility and efficiency of the post-reconstruction operation of a combined heat and power turbine. [ABSTRACT FROM AUTHOR]

Control valves are essential components of the energy, nuclear, process, and the oil and gas industries. They are needed for the accurate control of flow rate, pressure, and temperature crucial to the success of reactions in chemical processes and delivering the right amount of fluid to downstream facilities for storage, transport, or sale. As a result, the optimal design of control valves for being fit for purpose and for energy efficiency is of crucial industrial and commercial importance. To achieve optimal design, computational fluid dynamics is used as a powerful tool for the analysis and design of many process units including control valves. The full three-dimensional CFD simulations are useful but can be computationally expensive and time consuming if many designed needs testing. Furthermore, rapid solutions may be needed for testing many initial design configurations or for digital twin purposes where real time or near real time solutions are needed. One way of achieving quick solutions is the use of one-dimensional approximations of the high-fidelity simulations 3D flow within the valve. In this study, CFD simulations were carried out and used to establish a 1-D numerical model to predict the flow within a control valve having a trim with a complex geometry. Five valve opening positions (20, 40, 60, 80, and 100%) and two inlet flow velocities of 1 and 2 m/s were simulated. The valve flow coefficient Cv for each of the 10 cases was collected along the valve-pipe system on fifteen local planes and used to build the 1-D model in which the Cv is correlated with the VOP, Reynolds number, and length-diameter ratio. It was shown that this data driven model resulted in a coefficient of determination R2 value of 0.82 when compared with the underlying data and can be used with confidence for initial design and digital twin applications. [ABSTRACT FROM AUTHOR]

In this paper, a simplified methodology to increase the water distribution equity in existing intermittent water distribution systems (WDSs) is presented. The methodology assumes to install valves in the water distribution network with the objective to re-arrange the flow circulation, thus allowing an improved water distribution among the network users. Valve installation in the WDS is based on the use of algorithms of sequential addition (SA). Two optimization schemes based on SA were developed and tested. The first one allows identifying locations of gate valves in order to maximize the global distribution equity of the network, irrespectively of the local impact of the valves on the supply level of the single nodes. Conversely, the second scheme aims to maximize the global equity of the network by optimizing both location and setting (opening degree) of control valves, to include the impact of the new flow circulation on the supply level of each node. The two optimization schemes were applied to a case study network subject to water shortage conditions. The software EPA Storm Water Management Model (SWMM) was used for the simulations in the wake of previous successful applications for the analysis of intermittent water distribution systems. Results of the application of the SA algorithms were also compared with those from the literature and obtained by the use of the multi-objective Non-Dominated Sorted Genetic Algorithm II (NSGA II). The results show the high performance of SA algorithms in identifying optimal position and settings of the valves in the WDS. The comparison pointed out that SA algorithms are able to perform similarly to NSGA II and, at the same time, to reduce significantly the computational effort associated to the optimization process. [ABSTRACT FROM AUTHOR]

Featured Application: The proposed data quality metric and visualization is applicable to sets of independent, numeric variables, which are provided as input variables for regression models. The metric measures a task-dependent aspect of data quality requiring an assessment by experts of the data mining task. In this paper, condition monitoring of control valves is uses as running example. The so-called 'Industrie 4.0' provides high potential for data-driven methods in automated production systems. However, sensor and actuator data gathered during normal operation of the system is often limited to a narrow range of single, specific operating points. This limitation also restricts the significance of condition-based maintenance models, which are trained to the narrow data. In order to reveal the structure of such multi-dimensional data sets and detect deficiencies, this paper derives a data quality metric and visualization. The metric observes the feature space and evaluates the completeness of data. In the best case, the observations utilize the whole feature space, meaning all different combinations of the variables are present in the data. Low metric values indicate missing combinations, reducing the representativeness of the data. In this way, appropriate countermeasures can be taken if relevant data is missing. For evaluation, a data set of an industrial test bed for condition monitoring of control valves is used. It is shown that the state-of-the-art metrics and visualizations cannot detect deficiencies of completeness in multi-dimensional data sets. In contrast, the proposed heat map enables the expert to locate limitations in multi-dimensional data sets. [ABSTRACT FROM AUTHOR]

Patients with COVID-19 are not eligible for any therapy. Patients who have had respiratory failure and are unable to provide oxygen via noninvasive means obtain supportive care in ICUs. Since the onset of the outbreak, every sick COVID-19 patient has received oxygen via a mechanical ventilator. This study describes and simulates the transient stability of systems in an automated pressure regulator utilizing a single-acting cylinder in a clinical ventilator. These components include horizontal controllers, control devices, connecting tubes, and PID for electro-pneumatic control. Increased system stability and nonlinearity in electro-pneumatic actuator systems are accomplished by the implementation of PID. The redesigned PID control architecture was enhanced with alternative acceleration feedback through the close loop with an integral control method to get the system stable. This introduces the standard value N from the outside vicious circle and applies a form control law to integrate all reference control supply through into the gadget. Even as proportional gain (K p ) gets increased, the controller output would increase proportionately while maintaining the exact degree of accuracy. A derivative term boosts the ability of the K d regulator to "detect" malfunctions. The integral term of the K i controller minimizes its set point distortion. The system was updated to make it feasible for transferrable knowledge and competencies by incorporating real industrial components. The completed fluid control system was simulated through FluidSIM, which is frequently helpful for educational purposes., Competing Interests: The authors declare the following financial interests/personal relationships which may be considered as potential competing interestsI, Joseph F. Kayode, the corresponding author, and on behalf of the co-authors: Olufemi S. Amudipe, Bernard A. Adaramola, Osafehinti Olatunbosun declare that there is no conflict of interest. If there are other authors, they declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (© 2024 The Authors.)

Problems of ensuring the high efficiency of steam turbines during operation in partial modes are considered. It is noted that the decrease of steam throttling losses in the control valves has the greatest impact on the efficiency when operating in such modes. A brief overview of known techniques for increasing the efficiency of turbines by optimizing the operating modes of the control stage and the steam admission system, which consist in obtaining additional throttleless modes due to the combined operation of control stage nozzle boxes with different number of nozzles, is given. However, when implementing such techniques in dynamics, problems and limitations arise associated with the need for abrupt switching of control valves. A promising method (algorithm) for controlling the control valves of a steam turbine that ensures the optimization of the operating mode of the control stage and the minimum throttling losses in the control valves is proposed. The technology for implementation of the proposed control method, its advantages over the traditional one, and development prospects are stated. On the example of the T-295/335-23.5 turbine, the results of calculating the efficiency of the control stage with sequential and optimized steam admission, carried out by the proposed control method, are presented. The tests of optimized steam admission implemented by two methods, traditional and proposed one, are carried out on the mathematical model of T-295/335-23.5 turbine. The test results are presented in the form of graphs of transient processes. It is shown that, due to the optimization of steam admission by the proposed control algorithm for control valves, the disadvantages inherent in the implementation of the traditional method are eliminated, namely, the quality of transient processes is increased, there are no abrupt switching of control valves, the amplitude of steam temperature fluctuations in the nozzle boxes decreases, and it becomes possible to control the rate of their heating during optimization. [ABSTRACT FROM AUTHOR]

The experience of operating powerful energy steam turbines has clearly shown that a significant share of losses with reduced steam consumption is accounted for by the steam distribution system, which is characterized by intensive throttling of steam entering the turbine's flow section. Of the two main steam distribution systems—throttle and nozzle—nozzle steam distribution has an obvious advantage, where, unlike throttle, a reduction in steam flow through a turbine is achieved by throttling not only the entire steam stream but only part of it in a series of consecutively opening valves. To implement this method of steam distribution, it was necessary to introduce a special regulating stage into the turbine flow section, separated from the remaining stages by a regulating stage chamber (mixing chamber) designed to equalize uneven velocity fields at the entrance to the first unregulated stage, which are especially distinct with partial turbine loads. A detailed analysis of the advantages and disadvantages of the throttle and nozzle steam distribution is given and it is indicated that, taking into account all the additional consequences associated with the use of nozzle steam distribution, its advantage over the throttle becomes noticeable only when the turbine load is reduced by more than 25%. To eliminate the disadvantages inherent in the nozzle steam distribution, it is proposed to move the mixing chamber (chamber of the control stage) outside the turbine casing, thereby eliminating the control stage and greatly simplifying the supply of steam to the high-pressure cylinder of the steam turbine. In conclusion, a constructive solution for nozzle steam distribution with an external mixing chamber is proposed. [ABSTRACT FROM AUTHOR]

Friction is one of the most frequent causes of oscillations in process control loops. Normally, the first step in resolving this problem should be to stop the process and to perform valve maintenance. However, it is not always possible to do it, because it can lead to a loss of production and some processes are not simple to halt, e.g. a nuclear power plant or an oil refinery. Therefore, it is important to find other ways to solve this problem. Lately, many academic works have proposed the use of the integrative sliding mode controller to reduce the friction effect in control loops. This paper proposes to discretize this controller and to implement it in a microcontroller, acting as a control valve positioner. The experiments were conducted in a hardware-in-the-loop simulation environment running in real time. Tests are performed under various conditions, and the results are compared to a widely used friction compensation algorithm and a control disable technique. The results show that the implementation of the sliding mode controller in digital positioners is an interesting alternative for friction compensation in control valves in the industry. [ABSTRACT FROM AUTHOR]

• Nonlinear optimization method for stiction quantification and process identification. • Hammerstein framework and a smoothed stiction model are deployed. • The proposed approach is proved fast and efficient over a grid-search method. • MPC model is augmented with the identified valve stiction dynamics. • Stiction aware MPC regulators outperform the traditional formulation. A common source of poor control performance in industrial processes is represented by stiction in control valves, which often induces offset, oscillating behavior, and even loss of stability. Recent studies have investigated the effectiveness of embedding stiction models into model predictive controller (MPC) schemes, moving from stiction unaware to different stiction aware formulations, which help to remove fluctuations and may guarantee higher set-point tracking ability. To this aim, along with the process model the controller needs to use a dynamic model of sticky valves. This paper proposes an efficient, computational approach to obtain both valve and process dynamics, under the framework of Hammerstein system identification, which is based on nonlinear, gradient-based, numerical optimization. In order to improve the computational behavior and effectiveness of the methodology, a recently proposed smoothed model of stiction is deployed. The proposed methodology is validated in several (single-input single-output, and multivariable) examples, where the effectiveness of the obtained stiction aware MPC regulator is also evaluated against a stiction unaware counterpart. [ABSTRACT FROM AUTHOR]

Safety and instrument engineers regularly analyze the noise in different types of valves to reduce its effect in sectors of the oil and gas industry such as offshore, refineries, and petrochemical plants. This paper reviews the mitigation strategies used to reduce acoustic fatigue and the risk of hearing damage from pressure safety valves and control valves used in piping systems. These two types of valves can generate high-frequency acoustical energy downstream of the valves. Different strategies are used to mitigate noise levels, such as installation of low-noise valves, process optimization to reduce the flow or delta pressure across valves, changing the valve design, acoustic piping installation, and increasing piping thickness. This paper discusses a case study of a noise calculation for a 12″ × 10″ pressure safety valve (PSV) at 1 m and 30 meters from the PSV discharge. The calculated noise level based on API 521, the standard for PSVs, has been compared with the maximum allowable noise limit from PSVs. The maximum allowable noise limit is calculated based on the NORSOK L-002 standard developed by Standards Norway. If the calculated noise level based on API 521 exceeds the allowable or acceptable noise limit based on NORSOK standards, the piping wall thickness should be increased to mitigate the risk of acoustic fatigue. The 12″ 6MO piping wall thickness outlet line of PSV is calculated based on the ASME B31.3 process piping code. The outlet pipe from PSV is in 6MO UNS 31254 material, which is expensive. Fortunately, there is no need to increase the piping wall thickness if the calculated noise based on the API 521 standard is within the accepted noise limit in the NORSOK standard. [ABSTRACT FROM AUTHOR]

Control valves used in energy systems are often integrated with trims having well designed flow paths to regulate fluid flow. These trims, known as multi-stage continuous-resistance trims, comprise of staggered arrangement of circular cylinders enabling pressure drop reduction in controlled stages. The trim design process currently used doesn't ensure good local flow characteristics and relies almost entirely on the global performance indicators. The existing design largely ignores the effects of geometrical features of the trim, resulting in severe performance issues locally. In the present investigation, unique geometry-dependant local flow parameters have been analysed, using Computational Fluid Dynamics, and integrated with the global performance indicators to develop an improved trim design. Novel geometry and flow based parameters have been developed that uniquely relate the local flow behaviour within the trims to their corresponding geometrical parameters. It has been observed that the change in geometrical parameters of the trim significantly affects trim's performance, for example, reduction in the cylinders' dimensions, under same operating conditions, reduces the normalised pressure drop, flow velocity and energy by 28.4%, 26.8% and 37.9% respectively. The work highlights the need for modification in existing trim design methodology. • To critically analyse the local flow behaviour within a continuous-resistance trim. • Development of novel parameters to quantify local and global flow characteristics. • Effect of geometrical features of the trim on local and global performance indicators. • Development of a novel parameter representing the geometrical features of the trim. • Development of an improved trim design for enhanced energy performance. [ABSTRACT FROM AUTHOR]

Additive Manufacturing methods have been gaining popularity over the traditional manufacturing methods in the past three decades due to shorter product development cycles and reduced manufacturing costs. Selective Laser Melting is one of the most popular methods of Additive Manufacturing. In this paper, the effect of the manufacturing method on the performance characteristics of disc stack trims manufactured by Selective Laser Melting is investigated. Initially manufactured trim showed a reduction in the flow capacity as compared to the trim manufactured by Electron Discharge Machining. The reason for the reduction in flow capacity was found to be the increased surface roughness of the trim manufactured by Selective Laser Melting. Therefore, changes were made to the process parameters within the manufacturing method to improve the surface finish and its corresponding effect on the valve trim's performance was assessed. Furthermore, a new design of the disc stack trim to aid the manufacturing method was also tested. The results showed that the changes to process parameters produced a negligible effect on the trim's performance but changes to the design of the valve trim resulted in improvement of the performance. Results thus indicate that for critical applications it may be necessary to alter the design of the components to derive most benefits from additive manufacturing technology. [ABSTRACT FROM AUTHOR]

Highlights • Three different formulations of MPC to handle stiction in control valves. • An appropriate inverse model is implemented within the stiction inversion MPC. • A suitable compensation method is needed as a warm start in stiction embedded MPC. • Suitable choices of objective functions and constraints improve tracking ability. • Stiction embedding MPC can ensure tracking performance and stiction compensation. Abstract This paper presents different formulations of Model Predictive Control (MPC) to handle static friction in control valves for industrial processes. A fully unaware formulation, a stiction embedding structure, and a stiction inversion controller are considered. These controllers are applied to multivariable systems, with linear and nonlinear process dynamics. A semiphysical model is used for valve stiction dynamics and the corresponding inverse model is derived and used within the stiction inversion controller. The two-move stiction compensation method is revised and used as warm-start to build a feasible trajectory for the MPC optimal control problem. Some appropriate choices of objective functions and constraints are used with the aim of improving performance in set-points tracking. The different MPC formulations are reviewed, compared, and tested on several simulation examples. Stiction embedding MPC proves to guarantee good performance in set-points tracking and also stiction compensation, at the expense of a lower robustness with respect to other two formulations. [ABSTRACT FROM AUTHOR]

Control valves are very important actuators in the process industry. Due to friction in the stem, they present a nonlinear behavior, which can generate errors in the stem position and oscillations in control loops. This paper presents five control algorithms based on feedback linearization technique, to deal with pneumatic control valves affected by high friction in their stems. These control algorithms measure the valve position and manipulate the actuator pressure, acting as a valve positioner. The paper also shows practical results with a control valve operating in a real flow control loop. [ABSTRACT FROM AUTHOR]

This paper proposes a non-iterative method to perform the simulation of water distribution systems with pressure driven demands using EPANET2 without the need to use its programmer’s toolkit. The method works for single period simulation (snapshot) and for extended period simulation (EPS) as well. It is based on the addition of a flow control valve (FCV), a throttle control valve (TCV), a check valve (CV) and a reservoir to each demand node in the network, in addition to a list of simple controls to modify the setting of the FCV and TCV in each time step. The main advantages of this approach are: 1. the source code of EPANET2 is not modified, 2. the toolkit functions are not needed for the simulation and they remain available for further uses, 3. the extended period simulation (EPS) is performed by EPANET2 and it carries tank levels, demand variation and other time-changing variables internally. The performance of the method is tested in two benchmark networks and a real size network with pumps, tanks and a 24 h demand pattern. The results show that the method computed the pressures and outflows accurately and that the computational time required is not significantly higher than a demand driven execution in most cases. [ABSTRACT FROM AUTHOR]

A novel model free stiction compensation scheme is developed which eliminates the oscillations and also reduces valve movement, allowing good setpoint tracking and disturbance rejection. Pulses with varying amplitude are added to the controller output to overcome stiction and when the error becomes smaller than a specified limit, the compensation ceases and remains in a standby mode. The compensation re-starts as soon as the error exceeds the user specified threshold. The ability to cope with uncertainty in friction is a feature achieved by the use of pulses of varying amplitude. The algorithm has been evaluated via simulation and by application on an industrial DCS system interfaced to a pilot scale process with features identical to those found in industry including a valve positioner. [ABSTRACT FROM AUTHOR]

Multistage severe service control valves are extensively used in various energy systems, such as oil & gas, nuclear etc. The primary purpose of such valves is to control the amount of fluid flow passing through them under extreme pressure changes. As opposed to the conventional valves (butterfly, gate etc.), control valves are often installed in energy systems with geometrically complex trims, comprising of various geometrical features, formed by a complex arrangement of cylindrical arrays. The pressure within the trim varies in controlled steps and hence, cavitation resistance can be embedded in the trim through improved design process for the trim for severe service applications in energy systems. The flow characteristics within a control valve are quite complex, owing to complex geometrical features inherent in such designs, which makes it extremely difficult to isolate and quantify contribution of these features on the flow characteristics. One of the most important design parameters of such trims is the flow coefficient (also known as flow capacity) of the trim which depends on the geometrical features of the trim. The design of valves for particular performance envelop within the energy systems depends on effects of complex trim geometrical features on performance characteristics; hence, the focus of recent research is on quantifying the hydrodynamic behaviour of severe service control valves, including the trims. This includes the estimation of the local flow capacity contributions of the geometrical features of the trim through detailed numerical investigations. In this work, a tool has been developed that can be used to predict the local contribution of geometrical features on the flow coefficient of the trim. It is expected that this work will result in better performance of the energy systems where these valves are used. [ABSTRACT FROM AUTHOR]