Pressure Reducing Valves Research Articles

Algorithm for Appropriate Design of Hydroelectric Turbines as Replacements for Pressure Reduction Valves in Water Distribution Systems

Gravity flow water distribution systems (WDSs) are used to permit water flow from an input point of highest elevation (source) to the terminal points of a system (consumers). In such WDSs, typically, there is no need for external power to maintain the flow due to the typical high gradients that exist. However, those gradients cause high water velocity and pressure to some network areas that could potentially lead to pipes bursting. Currently, the only means to regulate pressure within allowable range are Pressure Reduction Valves (PRVs). They are installed at various locations, but they cannot utilize the existing hydropower potential in terms of electrical energy production. This paper provides a methodology for hydro-turbines dimensioning, so that they mimic PRV operation in terms of pressure regulation while producing power efficiently. This includes an algorithmic process within which the proper turbine design and performance prediction are initially determined, and then, via an interconnection between EPANET and MATLAB, the hydraulic behavior of their operation within the water network is modeled and simulated. The methodology has been tested with simulations of a typical urban WDS. The results indicate that the produced turbine geometries mimic PRV action at the respective locations with more than 1% accuracy during 70% of the time (2% maximum error), while producing electric energy with hydraulic efficiency over 60%.

Improved Prediction Model and Utilization of Pump as Turbine for Excess Power Saving from Large Pumping System in Saudi Arabia

The throttling process is frequently encountered in many industrial practices utilizing Pressure Reducing Valves (PRVs). This process is typically used to control pressure and flow in pipeline networks. The practice of utilizing PRVs is considered simple and cheap in terms of installation cost and control. It dissipates the excess fluid energy that can be used for other purposes. This paper studies the feasibility of utilizing the Pump as Turbine (PAT) concept to partially recover the excess power dissipated from PRVs located at the discharge lines of refined product shipping pumps at one of the hydrocarbon distribution facilities in Saudi Arabia. Multiple PAT installation layouts have been studied to achieve this goal, selecting the optimum option to maximize the power recovery. The final selection of PAT was conducted to achieve a reasonable payback period. A new method for predicting the pump performance in reverse mode was developed depending on the manufacturer’s pump performance curves. The comparison of the proposed model with experimental data and previous models for three modes of operation reveals that the proposed model in this paper’s results either have the minimum deviation or the second minimum deviation out of all models. In the case of flow ratio prediction, the predicted deviation is merely 3.83%, −1.14%, and 1.35% in three modes of operation. For power prediction, the proposed model is the best and the only reliable model out of all with the least deviation of −7.48%, 0.07%, and −3.16% in three modes of operation. The economic analysis reveals the Capital Payback Time (CPP) for five optimum PATs is around 5 years. The new method was also validated against previous models showing more precise performance prediction of multistage centrifugal pumps running in turbine mode.

Complexities of the urban drinking water systems in Ethiopia and possible interventions for sustainability.

The online version contains supplementary material available at 10.1007/s10668-022-02901-7.

Pressure regulation and energy recovery in water distribution networks using pumps as turbines

Water distribution networks (WDNs) are considered a potential renewable energy source, as they have more than enough pressure energy to deliver water to users. To control excessive pressure, WDNs are commonly divided into district metered areas (DMAs) with pressure-reducing valves (PRVs). The energy wasted by PRVs can be recovered using pumps as turbines (PATs). However, selecting the appropriate pump remains a challenge, as it must account for daily pressure and flow variations from consumers (off-design conditions). In this article, a combination of models was validated and applied to select the suitable pump for operating in an actual WDN. The replacement of two PRVs with PATs in a real network, previously divided into two DMAs and operating at constant speed was investigated. Economic and environmental analyses were also conducted. PAT1 was technically superior to PAT2, as PAT2 exhibited negative outlet pressure, affecting the pressure in DMA2. Optimal efficiencies are achieved at flow rates corresponding to the pump’s best efficiency point or near it, mimicking pressure control as if they were the valves themselves. The most efficient pump recovered 4,331 kWh/year, equivalent to a reduction of 1,732,400 gCO2/year, serving two households categorized as low-income. PATs proved to be a viable alternative, with a payback period of 2.1 years, as it can recover renewable energy. However, for effective pressure control in WDNs, other operational strategies, such as variable speed operation, should be explored.

Bubble CPAP respiratory support devices for infants in low-resource settings.

Approximately 46% of the 5.2 million annual under-5 deaths derive from neonatal conditions commonly associated with hypoxemia or acute respiratory distress. It has been estimated that 98% of these deaths occur in low- and middle-income countries (LMICs).Effective implementation of noninvasive respiratory support at all levels of healthcare could significantly reduce neonatal mortality. Several factors limit the widespread and effective implementation of noninvasive respiratory support in LMICs, including inadequate infrastructure, lack of proper instrumentation, shortage of skilled staff, costly disposables, and difficulties in the supply of consumables and spare parts. The aim of this state-of-the-art paper is to provide a detailed evaluation of the commercially available devices providing noninvasive respiratory support in LMICs, focusing on bubblecontinuous positive airway pressure(bCPAP). bCPAP might be administrated using a variety of different commercial devices, including devices specifically designed for LMICs, as well as using self-made systems. We described all the equipment required for safe and effective implementation of bCPAP, including air and oxygen sourced, pressure-reducing valves and flowmeters, air-oxygen blending systems, humidifiers, respiratory support devices, patient circuits, and airway interfaces. Specifically, we critically evaluated the advantages and disadvantages of various existing solutions within the context of low-resource settings.

Bypass Control strategy of a Pump as Turbine in a Water Distribution Network for energy recovery

Water Distribution Networks (WDNs) are subject to leakages due to pipes aging, resulting in water and pressure losses. These issues are solved by installing Pressure Reduction Valves (PRVs) to decrease the pressure in WDNs. Depending on the application, PRVs can waste large amount of energy, hence the substitution of PRVs with Pumps used as Turbines (PaTs) can be a good compromise in terms of economic and technical aspects to reduce leakages and recover energy. Currently the share of PaT is not yet fully developed due to the certain technical challenges yet to be addressed, as providing an affordable control strategy closer to the real working conditions in a WDN. Hence, more experimental activities are required. For these reasons, in this work an experimental campaign was carried with the aim to investigate the behavior of a PaT according to a possible layout that could be embedded into a WDN. Firstly, the machine was characterized both in pump and turbine modes. Moreover, the machine working conditions limits have been analysed in terms of runaway and blocked-rotor curves. Then, turbine tests were carried out at constant speed with a typical hydraulic control scheme by means of a PRV installed in series to the PaT and a second one installed on a bypass. As a result, this analysis highlighted the feasibility to recover a consistent amount of hydraulic energy otherwise wasted under typical WDN daily pressure and flow rate patterns, with promising results in terms of the operating point control of the machine.

A Graph-Theory-Based PRV Placement Algorithm for Reducing Water Age in Water Distribution Systems

Water age is the time taken for water to travel through a distribution system and reach the consumer. Generally, there is a trade-off between water pressure and water age in a water distribution system—higher pressure results in higher flow velocity, which often means shorter traveling time for the water, while lower pressure leads to slower flow and thus higher water age. Low pressure is a desired objective in a distribution system, as it reduces the physical stress on its components and minimizes water losses in the event of a leak. Low water age is a desired objective as well, as increased age is regarded as having a low water quality. Therefore, the two objectives compete with one another. The problem of trying to minimize both water pressure and age is a common problem in water distribution systems’ design and management. This paper introduces an algorithm for pressure reducing valves’ (PRVs) placement for reducing water age in water distribution systems. The algorithm is based on graph-theory elements and uses EPANET 2.2 for simulation and analysis. The method is demonstrated on two small scale examples, and the results present relatively significant improvements in respect to water age.

Viability of Pressure-Reducing Valves for Leak Reduction in Water Distribution Systems

Viability of Pressure-Reducing Valves for Leak Reduction in Water Distribution Systems

Pressure management in water distribution systems through PRVs optimal placement and settings

Optimal pressure management is a standard strategy for water loss minimization in water distribution systems (WDS). A pragmatic solution to regulating water pressures and leakage is introducing pressure-reducing valves (PRVs). This paper presents a valve positioning algorithm for optimally deciding the positions and setpoints of PRVs in a WDS. The algorithm derives the hydraulic solution of a WDS as a directed graph, established on the flow directions, using EPANET 2.2 and develops the downstream network supplied by water flowing out of every pipe in the network by applying the depth-first search method. The algorithm later recognizes the pipes leading to the most extended downstream networks, with pressures above the minimum required service pressure, and prioritizes them as the ideal locations for PRV placement. In this way, the proposed algorithm overcomes the limitations of the state-of-the-art in realistically conceptualizing the leakage reduction for optimally positioning the PRVs in WDS. Four studies with varying complexities were selected to demonstrate the algorithm's applicability for deriving pressure management solutions. The solution time for PRV positioning was in seconds for the first three networks and several minutes for the extensive fourth case study. The results corroborate the algorithm's ability to pinpoint the critical nodes with the most increased potential for downstream pressure control and for maintaining the pressure at the least required service pressure level through optimally allocating the PRVs, with acceptable setpoint values, within the pipe network.

Upgrade of Biaxial Mechatronic Testing Machine for Cruciform Specimens and Verification by FEM Analysis

This article deals with the modernization of an existing loading system for the analysis of elastic–plastic properties of sheet metals in plane stress. The identification of the beginning of plastic deformation of sheet metal in plane strain is important in the cold pressing of sheet metal and in the assessment of the load capacity of thin-walled structures in the automotive and aerospace industry. The design of the control structure of the hydraulic part of the loading system for cross testing was carried out to automatize the whole process of experimental evaluation. For this purpose, proportional pressure-reducing valves together with control electronics were designed. Thus, the loading system is a control system for which a control algorithm has been designed and implemented on a PC. A computer simulation was performed to verify the functionality of the load system. An FEM simulation was performed to verify the correctness of the proposed numerical models and to confirm the experimental results. A numerical nonlinear model of the selected material was applied for the specification of plastic deformations. From the results, it is possible to state the appropriateness of the used models as well as the appropriateness of using modernized equipment for subsequent analysis of the plastic deformation of cruciform specimens.

Advanced Pressure Management for Sustainable Leakage Reduction and Service Optimization: A Case Study in Central Chile

The central part of Chile has been in severe unprecedented drought for more than ten years, becoming a water-stressed area. ESVAL, one of the main water utilities in the Chilean water sector, is responsible for delivering potable water to the population and securing long-term supply in the vast majority of this area. In order to achieve this goal, ESVAL is implementing different measures, with pressure management being one of them. This paper aims to describe the works executed in La Calera city to implement a new advanced pressure management scheme on an existing pressure-reducing valve with two main targets: reducing leakage and improving the level of service to the customers. The results show that advance pressure management generates a 10.12% reduction in the minimum night flow while, at the same time, helping to improve the level of service to the customers reducing the number of times pressure falls below the minimum target set by ESVAL by 52%. It is concluded that pressure management facilitates quick water savings by optimizing the performance of existing pressure-reducing valves.

Numerical and experimental investigation of the effect of the optimal usage of pump as turbine instead of pressure-reducing valves on leakage reduction by genetic algorithm

The leakage, caused by design problems, pipe breakage, and fittings' failure, is a critical challenge that the beneficiaries face in the water distribution networks (WDNs). Control and management of the network pressure have always been considered helpful solutions to reduce the leakage in these systems. In the present study, locating and setting of the five pressure reducer valves (PRVs) have been optimized using GA (genetic algorithm) to minimize the leakage and make uniform pressure. Results show that the network leakage has reduced 21% from 34.53 lit/s to 27.26 lit/s. In the next step, the PRVs are replaced by two pumps as turbines (PATs) at two desirable points for converting extra elevation head of the real gravity WDN to generate electricity. It is also found that the performance of PATs in reducing the amount of leakage is similar to PRV, and there are slight differences. Therefore, nearly 153 MW/year is generated using two PATs that resulted in 15,000 $/year in cost-saving. As estimated, the cost for installing and operating two PATs is $14,000, so the return on capital will be at least one year.

Study on the influence of structural parameters on the flow and cavitation characteristics of tandem multi-stage pressure-reducing valves

Tandem multi-stage pressure-reducing valves (TMSPRV) are widely used for piping systems in the process industry. The flow coefficient is a central factor in valve design. The cavitation was caused by the local pressure of the fluid passing through the pressure-reducing valve being lower than the saturated steam pressure. Would cause serious damage to the pipeline system. Therefore, it is important to investigate systematically the effect of throttling structure parameters on the flow and cavitation characteristics of valves. In this paper, a combination of experimental and numerical simulations was used to study the effect of different structural parameters of valves on the flow coefficient. The results showed that increasing the flow channel inclination is beneficial to enlarging the flow coefficient. Meanwhile, the effects of different structural parameters on pressure and velocity of pressure reducing valves are discussed, the results indicated that increasing the inclination of the flow channel would reduce the vortex volume at the outlet. With the increase of the chamfer, the low-pressure area caused by the vortex in the near-wall surface decreases. Numerical simulations are conducted to investigate the effect of different structural parameters on the cavitation characteristics of valves. The numerical results showed that the flow channel inclination angle is 60° and the flow channel chamfer is less than 6 mm as the optimal value. In summary, considering the influence of structural parameters on flow coefficient, flow characteristics, and cavitation characteristics. The runner inclination angle is 60°, and the runner chamfer is 4 mm as the best value. The research work in this paper could provide technical support to achieve a better fluid pressure reducing and flow state of the TMSPRV under severe working conditions.

Predictive Control in Water Distribution Systems for Leak Reduction and Pressure Management via a Pressure Reducing Valve

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.

Use of hydraulic model in real water loss reduction and water distribution network operational cost lowering

Most of the small water companies supplying a small number of consumers with water are struggling with the extremely tight budget, often making any large-scale modernisation impossible. In effect network managed by these companies is often very leaky and unreliable. One possible and cheap way of leakage reduction is the reduction of average pressure in the network. Thanks to new computing technologies, the device selection process for pressure reduction is accurate and easy to do. This study uses the hydraulic model to select required pressure-reducing valves and correct locations accurately and adequately approximate the resulting absolute water loss reduction thanks to this approach.

A Field Experiment Verification of Theoretical Exponent N1 for FAVAD Method in Defining the Relationship of Pressure and Water Losses

The current problem of managing water losses in water supply systems relies on engineering predictions of expected outcomes based on pressure manipulations using hydraulic models or other computational methods. The objective of this experiment was to conduct a field test to validate the theoretical N1 exponent of the fixed and variable area discharges (FAVAD) method. By knowing the pipe material and measuring the pressure and minimum night flow (MNF), the N1 exponent can be defined and compared to recommendations in the literature. Field measurements and experiments were performed in a small settlement in Croatia consisting of 278 house connections and 7.4 km of PVC material pipe network. Pressure manipulation was performed on a pressure-reducing valve (PRV). The resulting value of N1 = 1.76 from the experiment agrees with the literature graphs, which indicate a value of N1 between 1.5 and 2.0. Considering the difference between the studied values and the theoretically calculated MNF of 4%, it can be concluded that the implementation of the presented methodology to determine the N1 exponent can be used in practice. This type of field testing is important because such tests are difficult to perform due to the extensive pressure manipulations during the tests, which can affect the consumers and cause disturbances in the water distribution.

Effects of impeller geometry modification on performance of pump as turbine in the urban water distribution network

Nowadays, by increasing energy consumption, micro-scale energy production has received a lot of attention worldwide. Pressure control and electricity generation using existing hydraulic energy are possible by substituting the Soft Pressure Regulation System (SPRS) for a pressure reducing valves (PRV) in urban water distribution network (WDN) pipelines. The economical benefit and short start-up time are unique features of the SPRS that uses a pump as turbine (PAT). In this study, the numerical and experimental results of a single-stage centrifugal pump in direct and reverse working modes were compared and validated. The effect of passage width increasing, adding splitter blades and simultaneous modification of these parameters on improving the hydraulic performance of the PAT in the working range are investigated. Geometric modifications do not have the same effect on hydraulic parameters and efficiency in all operating ranges due to the significant range of flow rate variations in the WDN. Therefore, the statistical analysis was performed to identify the optimum modifications based on the PAT's working time in the specified flow rate ranges. The results show that simultaneous modification of parameters in the range of part-load condition (0.8QBEP) to over-load condition (1.2QBEP) reduces losses while increasing efficiency and power generation.

Pumps as turbines regulation study through a decision-support algorithm

The water distribution network (WDN) is subject to water leakages due to pipes breaking, which induces a wastage of water and overconsumption of power for pumps. Leakages are directly related to pressure in the pipes. To reduce leakages, pressure reducing valves (PRV) are installed in water distribution networks to reduce pressure in the pipes. However, pressure reduction induces a loss of energy which is wasted within the PRV. To recover a part of this energy, pressure reducing valves can be replaced by using pumps as turbines (PATs). Since head and flow rates are variable in the WDN, it is necessary to regulate the PAT, which does not function properly under variable upstream conditions. In this paper, the hydraulic regulation (HR) and hydraulic-electric regulation (HER) methods are studied in economic and energy production terms. A comparison between HR and HER is based on results from two real sites. The study is carried out using an innovative decision-support algorithm, which is described in detail. The results show that adding electrical regulation improves energy production, but the increase in installation costs makes the sites less economically viable.

Performances of Pressure Reducing Valves in Variable Demand Conditions: Experimental Analysis and New Performance Parameters

Pressure Reducing Valves (PRV) play a critical role in Water Distribution Networks (WDN): they regulate pressure ensuring an efficient service to users and preventing damage to pipelines. In recent years, the attention of water utilities towards pressure management and leakage control led to the necessity of more flexible and responsive technologies that can guarantee a higher level of pressure control accuracy. Because of this the common performance parameters based on steady state conditions are no longer satisfactory to evaluate the effective behaviour of the devices when used in situations where demand can change. In the present paper the pressure control effectiveness of different types of PRV (electric actuated, pilot operated and direct acting) in variable demand conditions is discussed. The data used are from experimental tests, literature and field application. To assess valves’ pressure control performance, the use of new parameters, which consider the peak of pressure reached during control operations and the accuracy of target pressure regulation, has been proposed. The use of these parameters allows the comparison between different type of valves giving to WDN managers a direct overview on the valves ability to regulate pressure under variable demand conditions.

Strategy to Enhance Emergency Interconnected Operation of Water Distribution System

This study identified the causes of insufficient emergency interconnected operation (EIO) performance, such as pressure-related problems and connection problems caused by elevation differences between blocks, the characteristics and locations of emergency interconnection pipes (EIPs), and pumps. Then, it tested four strategies to improve the EIO performance, including increasing the EIP diameter or installing additional EIPs, pressure reducing valves (PRVs), or pumps. The advanced pressure-driven analysis model was applied to quantify the EIO performance improvement achieved using these strategies. Further, these strategies were tested in a real water distribution system. To solve the low-pressure problem, the EIP diameter was increased and an additional pump was installed; the former did not significantly improve, whereas the latter improved supply by 20–30%. To solve the high-pressure problem, PRVs were installed to maintain the EIO performance effectively. To solve connection problems, new EIPs were installed. Although this improved the supply performance, the installation of pumps was recommended to overcome elevation differences. The proposed strategies should contribute to the allocation of facilities such as EIPs, pumps, and PRVs for realizing effective EIO.