Pressure Reducing Valves Research Articles

Optimal Localization of Pressure Reducing Valves in Water Distribution Systems by a Reformulation Approach

Leakage reduction represents one of the most challenging tasks in managing water distribution systems (WDSs). An effective way to leakage reduction is to carry out network operational pressure management through optimizing locations and regulations for pressure reducing valves (PRVs) and system pressures. This leads to a mixed-integer nonlinear program (MINLP) with a large number of binary variables which make it difficult to solve by an available software package. In this study, instead of directly solving the MINLP problem, we reformulate it to a mathematical program with complementarity constraints which can be efficiently solved by available NLP algorithms. The binary variables are replaced by continuous ones with complementarity constraints to be satisfied by a penalization scheme. To improve the quality of the solution and also to accelerate the convergence, in each relaxed NLP the results of the binary variables are rounded to binary values with which the NLP problem is solved again to achieve a MINLP solution. The final solution will be determined by the best one among the MINLP solutions. The results from two case studies reveal new and better combinations of PRVs as compared with those given in the literature.

Exergoeconomic optimization of coaxial tube evaporators for cooling of high pressure gaseous hydrogen during vehicle fuelling

Gaseous hydrogen as an automotive fuel is reaching the point of commercial introduction. Development of hydrogen fuelling stations considering an acceptable fuelling time by cooling the hydrogen to −40°C has started. This paper presents a design study of coaxial tube ammonia evaporators for three different concepts of hydrogen cooling, one one-stage and two two-stage processes. An exergoeconomic optimization is imposed to all three concepts to minimize the total cost. A numerical heat transfer model is developed in Engineer Equation Solver, using heat transfer and pressure drop correlations from the open literature. With this model the optimal choice of tube sizes and circuit numbers are found for all three concepts. The results show that cooling with a two-stage evaporator after the pressure reduction valve yields the lowest total cost, 45% lower than the highest, which is with a one-stage evaporator. The main contribution to the total cost was the cost associated with exergy destruction, the capital investment cost contributed with 5–14%. The main contribution to the exergy destruction was found to be thermally driven. The pressure driven exergy destruction accounted for 3–9%.

Theoretical and Experimental Research on a Pressure-Reducing Valve for a Water Hydraulic Vane Pump

In order to control the high PV value between the vanes and the cam ring in a water hydraulic vane pump, a pressure-reducing valve with a constant pressure ratio was developed in this study. The pressure and leakage characteristics of the valve were theoretically analyzed by simulation and the experiments were also conducted based on the valve prototype. The theoretical analysis agrees well with the experimental results. Further, these results reveal that the pressure ratio of the valve decreases to the design value with the increasing working pressure. Additionally, the leakage of the valve rises simultaneously with the increasing working pressure and can be reduced significantly by decreasing the clearance between the valve body and the spool. The presented research not only proves the successful development of the pressure-reducing valve but also lays a foundation for the investigation of a high-pressure water hydraulic vane pump.

Why PRVs Tends to Oscillate at Low Flows

Abstract A pressure reducing valve (PRV) consists of a main valve and a PRV controller which senses the output pressure and adjusts the opening of the main valve to maintain the outlet pressure at a given set-point [2] . Although it is well known that PRVs tend to oscillate at low flows the problem is not properly understood. This research was motivated by an industrial case-study to remediate instability in the large scale pressure control scheme. The precise cause for the instability has been identified and the measures to improve the robustness of the generic pressure control schemes are proposed.

Recovery of Wasted Mechanical Energy from the Reduction of Natural Gas Pressure

At the present time in Romania, the transition from the natural gas transportation system to the distribution system is done only thru the use of pressure reducing stations. Here the pressure drop is usually done by using throttle valves or pressure reducing valves, where the gas energy is spent without doing any work. In this article we propose the use of turbo-expanders in the pressure reducing stations, where the natural gas pressure from the transportation grid is high and needs to drop to lower levels to enter the distribution grids, in this way part of the energy consumed in the compression stations are recovered. The plans are made at this time for a pilot project at the pressure reducing station in the city of Onesti, Bacau County.

Battle of Background Leakage Assessment for Water Networks Using Successive Linear Programing

Abstract This research attempts to solve the BBLAWN challenge. The examined town consists of several pressure zones with significant elevation differences, causing accesses water pressure and pipe leakage. The challenge of optimally resizing the water system, to meet future water demands and minimize leakage, was solved using a successive linear programming, minimum cost, optimal operation model that includes head loss constraints, leakage control, pipe diameter selection and pressure reducing valves. A combination of an optimization model and practical engineering experience was used in the positioning of the pressure reducing valves and sizing of pump stations and water tanks.

Energy Recovery in Water Distribution Networks. Implementation of Pumps as Turbine in a Dynamic Numerical Model

In complex networks characterized by the presence of private tanks, water managers usually apply intermittent distribution, thus reducing the water volumes supplied to the users, or use Pressure Reduction Valves (PRV) for controlling pressure in the network. The application of Pump As Turbines (PATs) appears as an alternative and sustainable solution to either control network pressure as well as to produce energy. In the present paper, the hydrodynamic model, already presented by De Marchis et al. (2011) was further developed introducing the dynamic analysis of PATs. The model was applied to a district of Palermo network (Italy) characterized by intermittent distribution and by inequities among the user in term of water supply.

BBLAWN: A Combined Use of Best Management Practices and an Optimization Model Based on a Pseudo-Genetic Algorithm

Abstract The paper presents a solution to the problem of the Battle of Background Leakage Assessment for Water Networks (BBLAWN) using a methodology that combines the use of Best Management Practices (BMPs) and an optimization model based on a Pseudo-Genetic Algorithm (PGA) as described in [1] . In a first stage, an analysis of marginal costs of pipes whose replacement would be potentially recommended was performed. Next, a network topological analysis to study the pipes that could potentially be closed in order to facilitate pressure control was done. Furthermore, a methodology for studying branched areas was also developed, determining possible location for pressure reducing valves (PRV). A significant reduction in the number of decision variables was obtained and a specific optimization model was developed.

Optimization and Simulation on Pressure-Reducing Valve in Water Hydraulic Vane Pump

High contact stress between the vane tips and the cam ring is one of the main obstacles to improve the working pressure of a water hydraulic vane pump. A pressure-reducing valve for regulating the bottom pressure of the vanes at the pump suction zone is presented in this paper. Through optimization and simulation, it is found that the throttle structure has great influence on the dynamic performance of the pressure-reducing valve, and the triangular-rectangular groove is proved to be more suitable for the valve among all the investigated grooves. The theoretical analysis results show that the use of the pressure reducing valve can obviously reduce the contact forces between the cam ring and the vanes at the suction zone of the pump. The work in this research provides a feasible solution to improve the working pressure of a water hydraulic vane pump.

Implementation of pressure reduction valves in a dynamic water distribution numerical model to control the inequality in water supply

The analysis of water distribution networks has to take into account the variability of users' water demand and the variability of network boundary conditions. In complex systems, e.g. those characterized by the presence of local private tanks and intermittent distribution, this variability suggests the use of dynamic models that are able to evaluate the rapid variability of pressures and flows in the network. The dynamic behavior of the network also affects the performance of valves that are used for controlling the network. Pressure reduction valves (PRVs) are used for controlling pressure and reducing leakages. Highly variable demands can produce significant fluctuation of the PRV set point, causing related transient phenomena that propagate through the network and may result in water quality problems, unequal distribution of resources among users, and premature wear of the pipe infrastructure. A model was developed in previous studies and an additional module for pressure control was implemented able to analyze PRVs in a fully dynamic numerical framework. The model was demonstrated to be robust and reliable in the implementation of pressure management areas in the network. The model was applied to a district of the Palermo network (Italy). The district was monitored and pressure as well as flow data were available for model calibration.

A mathematical model to evaluate apparent losses due to meter under-registration in intermittent water distribution networks

Apparent losses consist of water volume drawn from the network, consumed by users but not paid for. Those due to water meter under-registration were evaluated by means of a mathematical model able to analyse the complexity of intermittent supply systems with private tanks. This supply scheme is very common in the Mediterranean area where unexpected water shortage often happens and intermittent water supply is a common practice. In order to analyse such complex systems, a demand model, reproducing the effect of private tanks, and an apparent losses module were developed and coupled with an hydraulic network model based on the Global Gradient Algorithm (GGA). In distribution networks pressure reduction valves (PRVs) are often used by water utilities to control the pressure and reduce background losses. These practices could influence the performance of water meters. For this reason, a PRV model was implemented and integrated with the demand and the hydraulic network models to better estimate the effect of pressure management on real and apparent losses. The comprehensive model was applied to a real case study. The proposed modelling approach was used to identify regions of the network with high apparent losses. Furthermore, the model may be used to predict the results of a water meter replacement plan and of the installation of devices that could affect apparent losses.

Acoustic-Induced-Vibration Case Study for WDDM Onshore Facilities

Summary In gas applications with high-pressure drops and/or high-velocity gas flow, acoustic-induced vibration (AIV) occurs when very high sound levels are propagated in piping. If the sound levels are high enough, they will excite the circumferential vibration modes of the pipe. This allows the pipe to vibrate in and out as the sound wave moves through the piping. Most often this occurs downstream of pressure-reducing valves or safety-relief valves, but AIV can occur at any location where the pressure drop or mass flow rate is sufficiently large. The level of pipe wall vibration is so high that it can induce fatigue cracking of the pipe and can potentially cause catastrophic pipe failure. The West Delta Deep Marine (WDDM) concession onshore of the slug catcher M9001 had a recent failure in the flare header as result of accumulating AIV effect. As a consequence of this failure Enppi/Burullus and Foster Wheeler have undertaken an engineering assessment study to investigate the risk of AIV for the plant and determine the corrective and engineering solutions to protect the plant from any failure that may occur as a result of AIV. This paper will present a case study as reference for gas-production facilities to consider the AIV application in regard to the design phase, and what might have prevented fatigue of pipes during the operation phase.

자동 균압 방지 감압밸브의 감압성능에 관한 연구

It is necessary to use pressure reducing valves to provide required water pressure in water-based fire suppression systems of the tall buildings. In many cases, however, pressure reducing valves lose their function due to the phenomenon of pressure equalization caused by valve leak. This study carried out performance evaluation of the recently developed pressure reducing valve to prevent pressure equalization and found it can maintain designed pressure reducing ratio within 11% variation and prevent pressure equalization by automatic self-lock function of the piston.

Numerical simulation and structure improvement of double throttling in a high parameter pressure reducing valve

In this paper, a new pressure reducing valve (PRV) with an orifice plate is proposed. The main objective is to explain the mechanisms of pressure reduction and energy conversion in the new PRV. A numerical simulation method was used to investigate the PRV internal flow field and to analyze the throttling effects of the orifice plate and the transform of thermal parameters as outlet pressure, outlet temperature, velocity, and superheat. A structure improvement method for the valve body and orifice plate is put forward to reduce energy loss. The governing equations for internal flow numerical simulation are composed of the continuity, momentum, energy and k-e transport equations, based on isotropic eddy viscosity theory. Different valve plug displacement models were built to describe the double throttling process. Our analysis shows that the steam pressure drops twice and the degree of superheat increases. There are also lots of eddies which clog the flow channel and disturb the steam flow in the valve cavity after the valve plug and the outlet cavity. After modifying the structure, the numerical results show a better performance of steam flow.

Identification of the optimal entry points at District Metered Areas and implementation of pressure management

Nowadays, the implementation of pressure management in District Metered Areas (DMAs) is considered one of the most effective tools for leakage control, particularly in large networks and in systems with deteriorated infrastructures and with high pressure. The goal of the methodology proposed in this paper is to identify the optimal entry points at DMAs, determine the network needs in terms of reinforcement/replacement, and fix both the location and settings of different types of Pressure Reduction Valves (PRVs) for leakage control. This methodology is based on an optimisation model, which is solved by a Simulated Annealing algorithm, and the solutions obtained always fulfil the minimum pressure requirements for the network. The objective function comprises the total cost of the DMAs implementation and the economic benefits that can be achieved by pressure management. Finally, the results for two case studies are presented and discussed.

Modeling and Control of a Novel High-Pressure Pneumatic Servo Valve Direct-Driven by Voice Coil Motor

High-pressure pneumatic control valves have been widely investigated during last decades. The published literature includes experimental and analytical studies on both constant value on–off valve and pressure reducing valve, but rarely on servo valve. In this paper, a novel voice coil motor (VCM) direct drive high-pressure pneumatic servo valve (HPPSV) is proposed. The mathematical model of the HPPSV including electromechanical and fluid subsystem is presented. Furthermore, the hybrid control scheme consisting of a proportional integral differential (PID) controller with velocity/acceleration feed-forward and a disturbance observer is proposed to improve the control performance of the HPPSV, taking into account the factors such as compressibility of high-pressure gas, high nonlinearity of gas flow force and friction force. The experimental results show that the spool position control system based on the proposed control scheme has strong robustness and disturbance rejection capability, and the control accuracy of the valve spool position can be enhanced greatly compared with the conventional PID controller. The study has general implications in the development of high-pressure pneumatic servo valves and high-pressure pneumatic precision control field.

Research of Experimental System for Pressure Reducing Valve Performance and Life Test

This paper addressed the completed researching and developing procedure for the whole system with below parts： The pipe part of the whole system which according to the principle of the pressure reducing valve and the related standard; The electrical control system, adjusting control system, data collection system; We simulated customer’s operating on the valve based on PLC controlling the action of the Solenoid Valve which achieved the goal for life test .Meanwhile the paper introduced PPI protocol with which PLC computer communication each other. The experimental data of current capacity test, pressure characteristic test, flow coefficient (Cv) test and life test show the performance of the whole system is good.

구조-유체 연성해석을 통한 수도용 감압밸브에서의 유체유발진동에 관한 연구

In this paper, the structure-fluid coupled analysis is carried out in order to examine the cause of the vibration induced by fluid in the pressure-reducing valves for water. It is confirmed that there is the noise at the area of low frequency of 250Hz by measuring noise at pressure reducing valve. The flow analysis is performed by the commercial software ANSYS/CFX. The flow velocity of about 40 m/s is formed by nozzle effect, and so negative pressure is happened in the pressure reducing valve. The structure analysis is carried out with the load condition of pressure distribution by flow formed in valve. The rubber material at disk is deformed to the extent of closing up flow passage. It is confirmed that the disc deformation which is occurred repeatedly is due to noise and vibration at the pressure reducing valve.

Implementation of Hydraulic Modelling for Water-Loss Reduction Through Pressure Management

This study was conducted in the Konyaalti Water Distribution Network in Antalya, Turkey. The study area was divided into 18 district metered areas (DMAs) for better management of water losses. Water levels in reservoirs, flow rates, and water pressures were monitored on-line by the SCADA data system. A hydraulic model was calibrated and verified for each DMA using data provided by SCADA. The model results revealed that a number of DMAs exhibited high pressures, greater than 3.5 bars, and high minimum night flow (MNF) throughout the year. Also, the Infrastructure Leakage Index (ILI) for the study area was greater than 20, indicating high water losses. As a result of these findings, a pressure reducing valve (PRV) was installed at DMA No. 2 as an example and set at 3.0 bars resulting in considerable reduction in water losses. The optimum pressure level for setting the PRV was chosen using the hydraulic model. The same model was used to predict water savings due to pressure reduction. The predicted water savings were verified using long periods of flow rates and water pressure profiles. The predicted and measured water savings showed good agreement. The study concluded that hydraulic modelling is essential for applying appropriate pressure management strategies.

Genetic Algorithms for the Optimal Operation of Sprinkle Irrigation Systems under Deterministic Loading Conditions

The paper presents a methodology developed for the optimal management and operation of sprinkle irrigation networks. Some typical problems are presented and solved through Genetic Algorithms (GAs), assuming that the loads (demands) at nodes are cyclic and deterministically established. In particular, an algorithm for model calibration is first introduced, aimed at the minimization of the maximum errors between measured and calculated values. Since the operation of such systems is highly water and energy demanding, two algorithms for controlling pressure and pumps are described: the first is aimed at finding the optimal location and control of a set of devices (pressure reducing valves and/or closed gate valves) in order to maintain a desired range of pressure throughout the network, while the second is focused at finding the optimal regulation of inverters for variable speed pumps in order to minimize energetic costs. An application to a real system is finally presented.