Pressure Reducing Valves Research Articles

A lab prototype of pressure control in water distribution networks

A common strategy for leakage reduction in Water Distribution Networks (WDNs) is the use of Pressure Reducing Valves (PRVs). As well known, a relationship between pressure and water losses can be established, according to which reducing pressure results in reduced losses. In many cases pressure is greater than the minimum required for adequate service level, because of the variability of flow and pressure within the WDN. To increase the effectiveness of PRVs, a Real Time Control (RTC) of the regulated pressure can be developed, as pointed out by many researchers. Consequently, in the paper the issues arising from pressure RTC in a WDN is discussed. Laboratory experiments were carried out to assess the capability of the controller to achieve the set point pressure, regardless of the inlet conditions. A numerical model was also developed, showing good agreement with experiments.

Flow rate analysis of compressible superheated steam through pressure reducing valves

Steam flow is the main form for energy transfer in power plants, process industries, etc. The flow rate of the steam relates to the energy transfer amount directly. Pressure reducing valves are used for flow rate control of the compressible superheated steam in these piping systems. In this paper, a pressure reducing valve with a novel valve core is proposed. In order to analyze the internal flow characteristics of the compressible superheated steam and the flow rate adjustment performance of the proposed pressure reducing valve, a numerical model of DN80 pressure reducing valve is established. Then, the flow characteristics inside are studied numerically. Meanwhile, the flow rate adjustment performance is also carried out experimentally. Compared with the numerical and experimental results, it shows an agreement and both of them are similar to linear flow rate. Furthermore, a fitting equation for the flow rate prediction is carried out for the engineering applications under different working conditions.

Development and application of the anarchic society algorithm (ASO) to the optimal operation of water distribution networks

Abstract Optimizing the design and operation of urban water distribution networks (WDNs) is a complex, nonlinear problem. The optimization of WDNs can be performed for the pumping schedule, the location and elevation of reservoirs, the physical characteristics of pipes, and the placement of pressure-reducing valves, among other objectives. This study applies the anarchic society optimization (ASO) algorithm to find the optimal location and elevation of auxiliary tanks in urban water networks. The ASO is validated with mathematical benchmark functions, and is implemented to determine the location and elevation of auxiliary tanks in two urban water networks. The fuzzy reliability index for urban water network ranges between 74 and 79%, which is close to the global optima. The ASO exhibited better performance optimizing the reliability of WDNs than the genetic algorithm.

Combining pressure management and energy recovery benefits in a water distribution system installing PATs

Gravity can play a beneficial role in certain water distribution networks (WDNs), although sometimes high nodal pressures occur. Excessive pressure may lead to several negative effects regarding the network9s operation and life. Thus water utilities are obliged to implement pressure management (PM) policies. Instead of just ‘destroying’ energy using conventional measures, there are other PM options, like installing pumps working as turbines (PATs) that can recover energy at the same time. Hydro-turbines are widely used in small water energy production plants that produce electricity utilizing the water9s kinetic energy. PATs are micro-turbines (compared to the usual ones) used in reverse mode to ordinary pumps. Installing a PAT aims to not only produce energy but also keep the pressure of the downstream pipe to a desired level. Pressure reducing valves (PRVs) are able to decrease pressure too, thus reduce also water losses. This study attempts to exploit every possibility of replacing a PRV with a PAT and check a PAT9s ability to reduce pressure to acceptable levels as well as produce a significant amount of energy. Kozani9s (Greece) WDN is used as the case study. Various scenarios were checked, utilizing the network9s calibrated hydraulic model with intriguing results.

Characteristic analysis of a water hydraulic pilot-operated pressure-reducing valve

Comprehensive characteristics of a seawater hydraulic pilot-operated pressure-reducing valve with constant pressure output were analyzed. A rated pressure of 15MPa and a rated flowrate of 40L/min were offered in the numerical work. Static and dynamic analyses show good behaviors: The settling time is less than 0.2s, the output pressure variation is about 0.3MPa at the maximum when input pressure or flowrate is flucturing, and the steady external leakage is below 0.025L/min. The pilot spring regulates the output pressure and the main spring has an ability to adjust the output pressure variation faintly. The narrow hole diameter of the adjustable damping plugs is negatively related to the respond time. And appropriately raising the spring chamber volume can evidently reduce outlet pressure impact of the valve when input mutations happen.

Full-Scale PAT Application for Energy Production and Pressure Reduction in a Water Distribution Network

AbstractPressure management is an effective method to reduce water loss. A common way to reduce pressure and water loss in water distribution networks (WDNs) is to use pressure-reducing valves (PRV...

A New Device for Pressure Control and Energy Recovery in Water Distribution Networks

The potential energy of the water in Water Distribution Networks (WDNs) usually exceeds the amount needed for delivery and consumption and, at the present time, it is mainly dissipated through Pressure Reducing Valves (PRVs) or Open Water Tanks. The present study suggests the use of a new energy-producing device, a Cross-flow turbine with positive outlet pressure named PRS (Power Recovery System), which can provide the same service as PRVs and water tanks, with additional significant hydropower production. After a short presentation of the PRS, the management rules of the proposed device are laid out, according to two possible modes. In the ‘passive’ mode, the piezometric level downstream of the turbine is fixed at the sought after value, in the ‘active’ mode, the discharge is regulated according to the required value. The design criterion is then presented, based on a simple relationship linking dimensionless numbers. A PRS is finally designed for a typical water distribution network, serving the city of Palermo (Italy). The resulting cost-benefit analysis is compared with a similar one carried out in previous work for a regulation system based on the use of a Pump As Turbine (PAT). The comparison shows the improvement obtained by the use of the PRS, consisting of higher energy production, as well as lower construction and installation costs.

Leakage Reduction in Water Distribution Systems with Efficient Placement and Control of Pressure Reducing Valves Using Soft Computing Techniques

Reduction of leakages in a water distribution system (WDS) is one of the major concerns of water industries. Leakages depend on pressure, hence installing pressure reducing valves (PRVs) in the water network is a successful techniques for reducing leakages. Determining the number of valves, their locations, and optimal control setting are the challenges faced. This paper presents a new algorithm-based rule for determining the location of valves in a WDS having a variable demand pattern, which results in more favorable optimization of PRV localization than that caused by previous techniques. A multiobjective genetic algorithm (NSGA-II) was used to determine the optimized control value of PRVs and to minimize the leakage rate in the WDS. Minimum required pressure was maintained at all nodes to avoid pressure deficiency at any node. Proposed methodology is applied in a benchmark WDS and after using PRVs, the average leakage rate was reduced by 6.05 l/s (20.64%), which is more favorable than the rate obtained with the existing techniques used for leakage control in the WDS. Compared with earlier studies, a lower number of PRVs was required for optimization, thus the proposed algorithm tends to provide a more cost-effective solution. In conclusion, the proposed algorithm leads to more favorable optimized localization and control of PRV with improved leakage reduction rate.

Adaptive robust tracking control of a proportional pressure-reducing valve with dead zone and hysteresis

Proportional pressure-reducing valves (PPRVs) are typical proportional valves widely used in the hydraulic industry because they are inexpensive, not prone to malfunction, easy to handle and service. However, they suffer from performance degradations due to the existence of dead zone and hysteresis. An effective control method should be developed to improve the performance of PPRVs, as their characteristics significantly affect the entire hydraulic system. This article focuses on high-performance pressure-tracking control of a PPRV with dead zone and hysteresis. A non-linear phenomenological model is put forward to describe the characteristics of dead zone and hysteresis, as well as dynamic behaviour of the PPRV. The proposed phenomenological model is described using an ideal third-order linear model preceded by a dead zone term and a hysteresis term. To handle parameter uncertainties and uncertain non-linearities in the phenomenological model, an adaptive robust controller is synthesized without constructing a dead zone inverse or hysteresis inverse. The developed controller guarantees bounded pressure-tracking error and precise steady-state tracking accuracy. Comparative simulations and experiments with different pressure trajectories are carried out to verify the effectiveness of the proposed method. Both simulation and experimental results show that with the proposed adaptive robust control (ARC) approach, the non-linear dead zone and hysteresis may be well compensated and improved pressure-tracking performance achieved.

Optimization techniques for leakage management in urban water distribution networks

Abstract Reduction of leakages in water distribution systems (WDSs) is one of the major concerns for water industries. This paper presents a leakage reduction technique using pressure management by optimizing the water level in storage tanks, along with optimized control and localization of pressure-reducing valves (PRVs) in WDSs. A new mathematical tank and pump simulation algorithm is presented for controlling pressure in WDSs, by optimizing the water storage level in the tank depending upon the demand variations. The tank is used as a decision variable for the leakage reduction model. A modified reference pressure algorithm is introduced for improving PRV localization. A multiobjective genetic algorithm (NSGA-II) is used to find the optimized operational control setting of the PRV for leakage minimization. The proposed algorithm leads to a leakage reduction of 26.51% in Anytown WDS and 20.81% in a modified benchmark WDS. This technique leads to an appreciable reduction in leakage rate, with fewer PRVs required, taking into account constraints such as maintaining a lower hydraulic failure index (<0.01), emergency storage, etc. It can be concluded that the proposed novel leakage reduction technique provides a more cost effective and efficient solution for leakage control.

Selection and location of Pumps as Turbines substituting pressure reducing valves

Pressure control is a fundamental component of safe operation of water supply systems, mainly to reduce leakage, risk of disruption, and maintenance costs. System topology and topography can define high-pressure zones, and the use of Pressure Reducing Valves (PRVs) to maintain standard pressures in these zones is common. However, all energy available in the fluid is dissipated trough headloss. A turbine could be used instead of PRVs to produce electrical energy and to control pressure. The use of Pumps as Turbines (PATs) is recommended to reduce investment cost. Due to dynamic operations throughout the day, PATs operate under varying conditions of flow and head. This variation affects efficiency and headloss, which makes difficult the selection of PATs to substitute PRVs through conventional methods; therefore, this paper proposes a method for such selection. The method is based on maximization of energy produced, restricted to the system pressure limits. To solve this selection problem, the optimization technique of Particle Swarm Optimization (PSO) is used, and complete pump curves are used to simulate the PATs. In addition, this method is capable of identifying the best location on the network to install the PATs.

Theoretical and Experimental Research on a Three-Way Water Hydraulic Pressure Reducing Valve

A three-way water hydraulic pressure reducing valve (PRV) was developed in this paper for a test equipment in laboratory for adapting complex conditions. The designed PRV has a damping chamber with an orifice located at the spring chamber. Two types of throttles and orifice diameter were investigated through dynamic simulation and optimization, and their dimensions were determined and applied to the manufactured valve prototype. The static and dynamic performances of the valve were tested by experiments. At the preset pressure of 5.0 MPa, the outlet pressure variations for the pressure-reducing port and the relief port, are 0.73 MPa and 1.44 MPa, respectively, while the flow variation is up to 18.0 l/min. The experimental rising times and settling times of the PRV under the inlet pressure step for preset pressures of 5.0 MPa are 33.7 ms and 120.2 ms, respectively, and the overshoot is 3.76%. The test results at each preset pressure agree well with the simulation which verifies that the simulation model can be used to predict the dynamic performance of the PRV. The experimental results for the valve under flow step input conclude that it can work stably at small flow state. The research indicates that making the spring chamber a damping chamber by using an orifice is a feasible way to increase the pressure stability and the dynamic performance of the PRV. However, the damping effect of this structure is insufficient at high working pressure.

Micro hydro power generation from water supply system in high rise buildings using pump as turbines

Water supply is of vital importance for urban development, so the overall pressure in urban fresh water pipeline is usually very high to ensure consistent water supply throughout the urban area. Currently, pressure reducing valves (PRVs) are widely used to reduce water pressure in the water supply system (WSS) of high rise buildings to avoid water leakage and other danger in Hong Kong. The application of pump as turbine (PAT) appears as an ideal way for water head reduction as well as hydropower generation in water pipelines. In the present paper, the feasibility and performance of PAT used in WSS for electricity generation was investigated. In the research process, a PAT was first selected by empirical equations based on the given working conditions in one typical high rise building. After selection, CFD simulation and laboratory tests were carried out to study the performance of the selected PAT. Both the simulated and measured results show that the selected PAT is feasible for power generation and water head reduction. The comparison between numerical and experimental results indicate that the simulation outcomes could be used for performance prediction of PAT although the deviation exists. A PAT installation and control strategy was designed and tested in the hydraulic test rig, and the results show that the proposed PAT installation and control strategy performed well for avoiding excessive water head reduction at higher flow rates.

Valve exploiting the principle of a side channel turbine

The presented article deals with a side channel turbine, which can be used as a suitable substitute for a pressure reducing valve. Pressure reducing valves are a source of high hydraulic losses. The aim is to replace them by a side channel turbine. With that in mind, hydraulic losses can be replaced by a production of electrical energy at comparable characteristics of the reducing valve and the side channel turbine. The basis for the design is the loss characteristics of the pressure reducing valve. Thereby create a new kind of turbine valve with speed-controlled flow in dependence of the runner revolution. It is technical innovation and new renewable source of energy, which can be in future used in rehabilitation or projecting of pumped-storage power plants. It also increases the power of the power plant.

Pressure Management Through Optimal Location and Setting of Valves in Water Distribution Networks Using a Music-Inspired Approach

Pressure management through Pressure Reducing Valves (PRVs) is probably the most used approach related to the leakage management in Water Distribution Networks (WDNs). Its effectiveness in reducing the amount of water losses in existing networks has been highlighted in many papers. In this study, the topic is addressed with particular reference to meta-heuristic optimization techniques, that have proved to be very effective in producing good results with reduced use of computational resources. In particular, the application of the Harmony-Search (HS) method to the location and setting of a pre-fixed number of PRVs is proposed and discussed. A single objective optimization problem is defined which aims at the leakage reduction through the minimization of the water pressures. A double harmonic component is adopted for taking into account both the location and the setting of each PRV. The hydraulic constraints handled by a simulation software are considered as well. The approach is applied to a couple of WDNs: one is the Jowitt and Xu well-known literature test case and the other is a real WDN in Naples, called Napoli Est. The methodology has showed very good results compared to those obtained by using classical Genetic Algorithm techniques both in terms of leakage reduction and computation time.

Location and Setting of Valves in Water Distribution Networks Using a Harmony Search Approach

AbstractIn this paper, pressure management through pressure-reducing valves (PRVs) is discussed with particular reference to metaheuristic optimization techniques, which have proven to be very effe...

Energy saving in high-pressure reciprocating air compressor

ABSTRACTAir compressors account for a significant amount of electricity usage in Indian industries. The production of compressed air is one of the expensive processes practised in manufacturing industries. Our major aim in this project is to apply an energy recovery technique and on load reduction technique in high-pressure reciprocating air compressor. We applied our custom-designed energy recovery techniques and also analysed the limitation and the risks involved in the proposed technique. In the conventional method, the hot pressurised air coming out of the blow-moulding process is emitted into atmosphere, whereas in the proposed model the compressed air is recycled to the compressor receiver; also further energy reduction takes place due to reducing the operating pressure by introducing a pressure-reducing valve (PRV). The implementation of PRV reduces the loading time by 96 min/day, and energy consumption is reduced by 365.25 units/day.

Hydraulic Modelling for Pressure Reducing Valve Controller Design Addressing Disturbance Rejection and Stability Properties

Pressure reducing valves (PRVs) are widely used in water distribution systems to reduce excess pressure caused by variations in terrain elevation or by excessive pumping. The fundamental role of a PRV is to maintain a desired outlet pressure irrespectively of hydraulic conditions in the water distribution network (WDN). Unfortunately, even a stable PRV can exhibit poor disturbance rejection resulting in variations of outlet pressure around the setpoint due to randomly varying demands. The aim of this paper is to better understand this phenomenon and to develop models which would facilitate designing effective controllers considering the stability and disturbance rejection issues.

Selection of Pumps as Turbines Substituting Pressure Reducing Valves

Technical standards define operational limits for hydraulic parameters such as velocity or pressure. On this way, pressure control is a fundamental component for safe operation at water supply systems, mainly to reduce leakage, risk of disruptions and maintenance costs. The system topology and topography can define some high pressure zones and in this case the use of Pressure Reducing Valves - PRV - to maintain standards pressures on the sector is common. However, all the energy available on the fluid is dissipated trough headloss. A turbine could be used instead of the PRV to produce electrical energy and to control pressure. In general, the power available in these sites is under 100kW, so the use of Pumps as Turbines - PAT - is recommended to reduce the investment. Due of the dynamic operation trough a day, the PAT will operate under different conditions of flow and head. This variation will affect its efficiency and head loss, which difficult the selection trough conventional methods. Therefore, this paper proposes a method for PAT selection to operate instead a PRV. The method is based in the maximization of the energy produced, constrained to the pressure limits on each node of the network. To solve this problem, the optimization technique PSO is used and the available curves in literature, on the Suter plane, are used to simulate the PAT. The method is applied on a network and the results are compared with the PRV operation.

Network Analysis, Control Valve Placement and Optimal Control of Flow Velocity for Self-Cleaning Water Distribution Systems

In this paper, we consider the proactive control of flow velocities to maximise the self-cleaning capacity of the drinking water distribution systems under normal operations both through a change of the network topology and through an optimal control of pressure reducing valve (PRV) settings. Inspired by line outage flow distribution in electrical networks, we show how a fast network graph analysis of link closures can be used to estimate the potential changes in flow velocities, which are then used to determine the most favourable pipes for closure. Where closing of pipes cannot be used because of other conflicting objectives, we consider the optimal control of PRVs to maximise self-cleaning at peak demand periods. We formulate a novel optimisation problem to maximise the network operations for increased self-cleaning capacity, while satisfying hydraulic and regulatory pressure constraints at demand nodes. A new smooth objective function approximation for cleaning capacity of the network is proposed along with a scalable sequential convex programming method to solve the resulting valve optimization problems. We use a published benchmark network as a case study to show the efficacy of these new approaches.