CFD based investigations for the design of severe service control valves used in energy systems

Abstract

10 Multistage severe service control valves are extensively used in various energy systems, such 11 as oil & gas, nuclear etc. The primary purpose of such valves is to control the amount of fluid 12 flow passing through them under extreme pressure changes. As opposed to the conventional 13 valves (butterfly, gate etc.), control valves are often installed in energy systems with 14 geometrically complex trims, comprising of various geometrical features, formed by a 15 complex arrangement of cylindrical arrays. The pressure within the trim varies in controlled 16 steps and hence, cavitation resistance can be embedded in the trim through improved design 17 process for the trim for severe service applications in energy systems. The flow 18 characteristics within a control valve are quite complex, owing to complex geometrical 19 features inherent in such designs, which makes it extremely difficult to isolate and quantify 20 contribution of these features on the flow characteristics. One of the most important design 21 parameters of such trims is the flow coefficient (also known as flow capacity) of the trim 22 which depends on the geometrical features of the trim. The design of valves for particular 23 performance envelop within the energy systems depends on effects of complex trim 24 geometrical features on performance characteristics; hence, the focus of recent research is on 25 quantifying the hydrodynamic behaviour of severe service control valves, including the trims. 26 This includes the estimation of the local flow capacity contributions of the geometrical 27 features of the trim through detailed numerical investigations. In this work, a tool has been 28 developed that can be used to predict the local contribution of geometrical features on the 29 flow coefficient of the trim. It is expected that this work will result in better performance of 30 the energy systems where these valves are used. 31 32 Capacity, Energy Systems 34 35 1.0 Introduction 36 Valves are an integral part of any piping network and are used in a variety of industries for 37 various process control applications. The design of valves is a specialist area and the 38 performance of valves is integral to the performance of the energy systems. The severe 39 service control vales typically have very complex flow paths and it is necessary to have 40 understanding of flow characteristics through the complex pathways to eliminate undesirable 41 effects such as vibrations, noise and cavitation in energy systems. The designs of such valves 42 are carried out with the help of well-known standards but many times undesirable local flow 43 effects cannot be eliminated through such designs. The standards are continuously updated to 44 incorporate state of the art knowledge into the design process through extensive experimental 45 and numerical research work carried out all over the world. Newer designs are continuously 46 * Corresponding Author Tel.: +44 1484 472323 1 only partially applicable. In such cases a thorough fluid dynamic analysis is necessary to 2...

Integration of TRIZ and CFD to New Product Development Process

“…As illustrated in Figure 2, the valve flow characteristics are determined by the type of curve displayed when % lift (or valve opening position) is plotted against the % flow or valve flow coefficient (commonly referred to as Cv). The CV is defined as the number of gallons per minute (GPM) that can flow through a valve at 60°F with a pressure drop of 1 PSI (Asim, Charlton, and Mishra 2017). The following equation is used to calculate the Cv of a valve:…”

“…In the design stage, Computer Aided Design (CAD) technology has been applauded for its role in facilitating early design changes during the NPD process (Holmström, Liotta, and Chaudhuri 2017). In the flow handling equipment industry, Computational fluid dynamics (CFD) technology, is an analysis tool for monitoring and predicting flow behaviour functions by applying the equations of motion using discretised elements of a numerical model to analyse flow behaviour in a system (Asim, Charlton, and Mishra 2017) thereby saving costs by reducing over-reliance on experimental activities (Dhotre et al 2013;Goto 2016). CFD has been applied to various flow handling applications and is also useful in investigating flow path geometry changes for flow optimisation (Asim et al 2019).…”

Quantification of additive manufacturing induced variations in the global and local performance characteristics of a complex multi-stage control valve trim

“…Surface roughness was not modelled in their simulations as the trim disc used in this study was considered to be hydrodynamically smooth. Asim et al [15][16][17] and Oliveira [18] adopted the approach of 3-D simulations to conduct CFD simulations on the full three-dimensional body of the valve. These simulations showed very close agreement with the results from the experimental testing.…”

“…As the VOP increases, there is an increase in the flow capacity of the valve. Asim et al [15][16][17] conducted studies on the variation of pressure and velocity within the trim and highlighted the importance of local flow analysis within the trim which could be used for the development of better designs of the trim. They observed that cavitation may occur in the flow paths within the trim as the local static pressure at some locations around the cylinders may drop below the vapour pressure under extreme conditions of operation.…”

Numerical–experimental research on the influence of inclined angle on the flow characteristics of angle seat valve

“…By the combination of numerical simulation and experiments, the relationship between the flow coefficient, groove structure, flowing condition, fitting coefficient, and stable value was derived. By using the computational fluid dynamics (CFD), T. Asim et al [3] analysed the flow capacity of control valve at the high‐pressure differential condition. The flow coefficients with different valve components are determined, and the correlation between the valve inner structure and flow capacity is established.…”