Pressure Reducing Valves Research Articles

Pressure management in water distribution systems in order to reduce energy consumption and background leakage

Due to the seriousness of the water shortage crisis over the past decades, the need to manage water use has become more and more important. Pressure management in urban water distribution networks is one of the options that can significantly reduce water loss. The pressure reducing valve (PRV) and the variable speed pump (VSP) are two devices that are most used in WDS pressure management. In the present study, an optimization code was first proposed to estimate the instantaneous water demand based on the reported network pressures. According to the estimated instantaneous water demand, another optimization code is presented based on the DE algorithm to control the installed PRVs and VSPs. This results in the uniform distribution of the pressure and reducing the excessive pressure on the water network for all hours of the day, reducing the water leakage and energy consumption accordingly. The provided method has been applied to a real water distribution network in northern Iran. The results showed that by applying this method, the network background leakage and the energy consumption have been reduced by 41.72% and 28.4%, respectively, compared to a non-management mode.

Exergy Analysis of Steam Pressure Reduction Valve in Marine Propulsion Plant on Conventional LNG Carrier

Exergy Analysis of Steam Pressure Reduction Valve in Marine Propulsion Plant on Conventional LNG Carrier

Recapturing wasted energy in water pressure reducing valves via in-conduit hydropower generators

This paper models the water supply stations by establishing a laboratory scaled platform for investigating the in-conduit hydropower generators. An operation scheme is proposed to generate electricity from the wasted energy in the pressure reducing valves (PRVs). To maximize the generator efficiency, a control scheme is designed such that converting the wasted energy of pressure drop across the PRV to electricity does not affect the required water pressure and flow on the customer side. This scheme also preserves the generator from any damage by taking its operational range into consideration. The effectiveness of the proposed scheme is evaluated by testing the experimental setup in a laboratory scaled platform for different flow and pressure scenarios.

Leakage reduction in water distribution system using efficient pressure management techniques. Case study: Nagpur, India

Abstract Leakages in water distribution system (WDS) are directly proportional to its operating pressure. Pressure management is becoming an important technique for reducing leakages in the water networks. This paper presents a pressure management technique for leakage reduction in north central WDS of Nagpur City, India, using variable speed pump and pressure reducing valves (PRVs). Variable speed pump is utilized for eliminating pressure deficiency during high demand and for reducing excess pressure causing leakage reduction during lower demand, by controlling the pump speed. PRVs have been used for further leakage reduction. This paper proposes a modified reference pressure algorithm for determining the location of valves in WDS. A multiobjective genetic algorithm (NSGA-II) is used to determine the optimized control value of pressure reducing valve with respect to change in demand pattern and to minimize the leakage rate in the WDS. Proposed pressure management technique leads to leakage reduction of 16.57% to 26.30% with respect to changes in demand pattern, causing daily average saving of 5.066 Ml. Minimum required pressure is maintained on every demand nodes to avoid pressure deficiency in WDS.

Testing behavior and effects of PRVs and RTC valves during hydrant activation scenarios

This paper provides an insight into behavior and effects of pressure reducing valves (PRVs) and of valves controlled in real time (RTC) during hydrant activation scenarios, which determine high-flow conditions in water distribution networks (WDNs). The analysis is carried out through the pressure-driven unsteady flow modeling of an Italian WDN, in which a pressure control device is assumed to be installed in the pipe outgoing from the source. Scenarios are constructed considering alternatively a PRV or an RTC valve, as pressure control device, and two different sites for hydrant activation. The results highlight that, thanks to its capability of controlling the service pressure at the critical node, the RTC valve performs better than the PRV, which is regulated based on its outlet pressure. In fact, the adoption of the RTC valve attenuates pressure deficits in the network, above all when the control time step is suitably small to attenuate pressure head oscillations at the controlled node. An additional benefit of RTC lies in increased outflows from the hydrant. The benefits of the RTC valve are smaller when the hydrant is activated in more redundant parts of the network, where pipe water discharge variations put the system to a less severe test.

Water and energy saving potential by adopting pressure-reducing measures in high-rise building: A case analysis

Indoor domestic water demands are increasing rapidly in many cities of China, among the causes, water wastage due to overpressure outflow (OPO) at water distribution points in buildings, especially in high-rise buildings, is a factor that has not gained much attention. Field tests in 23 high-rise public buildings and laboratory tests were conducted to quantitatively evaluate the influence of water pressure on water consumption in buildings. The water-saving potential by adopting pressure reducing measures was theoretically analyzed and verified based on a case study. Results indicated that water consumption is closely related to water pressure and overpressure outflow is a very common culprit of water wastage in high-rise buildings. Pressure management measures, such as branch pipe pressure-reducing valves, can reduce water consumption in buildings and improve the comfortability of use as well. Based on the laboratory pressure–outflow characteristics study of different water appliances, water-saving potential of pressure reducing measures can be theoretically evaluated. Case study demonstrated a theoretical reduction of 19.4% in water consumption by adopting branch pipe pressure-reducing valves, an actual 14,773 m3 water (11.9% reduction) and 15,955 kWh embodied energy was saved in 2015 after the implementation of branch pipe pressure-reducing valves retrofitting measure. Therefore, despite the current measures of adopting high-efficiency water appliances and/or utilization of unconventional water resources in buildings, implementation of pressure management measures is highly recommended in designing water supply system for new high-rise buildings and reconstruction of water supply system in existing high-rise buildings, thereby, promoting water, energy saving, and development of green building. Practical application: Water and energy saving in building is gaining more and more attention, however, water wastage due to overpressure outflow in buildings has not gained much attention. Based on field and laboratory tests, the water and energy saving potential in building water supply system were evaluated theoretically and further verified by a case study. Results indicate that pressure management measures such as branch pipe pressure reducing valves (PRVs) can reduce water and energy consumption in buildings. We strongly suggest that pressure management measures should be implemented in buildings, thereby, promoting water, energy saving, and development of green building.

Exergy approach for advancing sustainability of a biomass boiler

An exergy analysis of the district energy plant at University of Idaho, Moscow, Idaho, USA is presented. Exergy flows through the components of the steam cycle through the biomass boiler are quantified to identify major sources of exergy destruction. A mathematical model is developed to determine sources of exergy destruction using measurements taken. The largest sources of exergy destruction are the boiler and furnace at 35% and 33% of the overall exergy losses, respectively, followed by the campus heating equipment at 5.7% and pressure reducing valve (PRV) at 3.5%. Parametric studies reveal that decreasing boiler steam pressure levels to reduce exergy destruction in the PRV results in increased exergy destruction rates in the boiler. Increasing boiler steam pressure levels instead reduces exergy destruction, but has negligible effects on the overall exergy efficiency of the complete cycle. This indicates that the PRV is limiting potential improvements in the boiler exergy efficiency.

Automation with renewable energy to optimize the exploitation of water supply networks in Ninh Thuan province

The research that was conducted on the water supply network of Phan Rang city, Ninh Thuan province, is aimed at using renewable energy to optimize the management and reduce the water loss. The research has conducted DMA (District Metering Area) setup, construction and installation of flow meter and pressure reducing valve chamber for flow and pressure control with active pressure regulation, and the use of hydraulic power generator to generate power at the site. Research results provide management agencies, in particular, water supply companies, with optimal solutions in network management and energy saving, reducing the amount of water loss effectively, thereby increasing revenue and saving clean water - precious resources are gradually depleted.

Self-excited Pressure Vibration in the Low-Pressure Pipeline Using an Automatic Pressure-reducing Valve (II)

Self-excited Pressure Vibration in the Low-Pressure Pipeline Using an Automatic Pressure-reducing Valve (II)

Relevance of hydraulic modelling in planning and operating real-time pressure control: case of Oppegård municipality

Abstract Technical best practices recommend pressure control as an effective countermeasure to reduce leakages in water distribution networks (WDNs). Information and communication technologies allow driving pressure reducing valves (PRVs) in real-time based on pressure observed at remote control nodes (remote real-time control – RRTC), going beyond the limitations of classic PRV control (i.e. with target pressure node just downstream of the device). Nowadays, advanced hydraulic models are able to simulate both RRTC-PRVs and classic PRVs accounting for unreported and background leakages as diffused pressure-dependent outflows along pipes. This paper studies how such models are relevant to support pressure control strategies at both planning and operation stages on the real WDN of Oppegård (Norway). The advanced hydraulic model permits demonstration that RRTC-PRVs in place of existing classic PRVs might reduce unreported and background leakages by up to 40%. The same analysis unveils that advanced models provide reliable evaluation of leakage reduction efforts, overcoming the inconsistencies of lumped indexes like the Infrastructure Leakage Index (ILI). Thereafter, the model allows comparison of three strategies for the real-time electric regulation of PRVs in some of the planned scenarios, thus supporting real-time operation of RRTC-PRVs.

Orthogonal optimization of a water hydraulic pilot-operated pressure-reducing valve

In order to optimize the comprehensive characteristics of a water hydraulic pilot-operated pressure-reducing valve, numerical orthogonal experimental design was adopted. Six parameters of the valve, containing diameters of damping plugs, volume of spring chamber, half cone angle of main spool, half cone angle of pilot spool, mass of main spool and diameter of main spool, were selected as the orthogonal factors, and each factor has five different levels. An index of flowrate stability, pressure stability and pressure overstrike stability (iFPOS) was used to judge the merit of each orthogonal attempt. Embedded orthogonal process turned up and a final optimal combination of these parameters was obtained after totally 50 numerical orthogonal experiments. iFPOS could be low to a fairly low value which meant that the valve could have much better stabilities. During the optimization, it was also found the diameters of damping plugs and main spool played important roles in stability characteristics of the valve.

Upgrading the Reliability of Water Distribution Networks through Optimal Use of Pressure-Reducing Valves

AbstractHigh pressure in water distribution networks may lead to more leakages, bursts, and excessive consumption. Therefore, an effective strategy to improve the reliability of the network is pres...

Hybrid Leakage Management for Water Network Using PSF Algorithm and Soft Computing Techniques

Reduction of leakages in water distribution system (WDS) is one of the major concerns for water industries. This paper presents a hybrid leakage reduction model using pressure management technique, performed by optimizing water storage level in the tank, along with optimized control and localization of pressure reducing valve (PRV) in water distribution system. Pattern Sequence-based Forecasting (PSF) algorithm is used for prediction of flow rate (demand) from the tank for next 48 h, to calibrate the future desire water storage level in the tank. A mathematical tank and pump simulation algorithm is proposed for optimization of water storage level in the tank. A modified reference pressure algorithm is proposed for efficient localization of pressure reducing valve. Multiobjective genetic algorithm (NSGA-II) is used for finding out the optimized operational control setting of the pressure reducing valve for leakage minimization. The proposed algorithm leads to better leakage reduction of 20.81% in modified benchmark WDS, with a reduced number of the pressure reducing valves. Constraints such as maintaining lower hydraulic failure index (<0.01), emergency water storage, etc. is also considered. It can be concluded that the proposed hybrid leakage reduction technique provides efficient as well as cost-effective solution for leakage control.

Leakage Control and Energy Recovery Using Variable Speed Pumps as Turbines

One of the primary concerns in water supply systems is pressure control. High pressure increases both leakage and the risk of pipes bursting, while low pressure can reduce the water supplied to consumers and allow the intrusion of pathogens. Therefore, the operation of the equipment must be optimized to avoid such problems. In high pressure zones, pressure reducing valves (PRVs) are commonly used for pressure control. However, the energy dissipated from head loss could be recovered to produce electrical energy. The use of pumps as turbines (PAT) in this case is an alternative to improve the system efficiency. However, owing to the dynamic operation, PAT performance drops significantly during some periods of the day. The use of variable speeds can solve this problem, but the PAT selection to optimize the operation remains an issue. Therefore, this paper presents a method to simultaneously select PATs and schedule their operation using variable speed to improve energy recovery and reduce leakage. Two networks are studied and the performance in leakage control is compared with the PRV operation.

Optimal design of water supply networks using an energy recovery approach

Abstract Water Distribution Networks (WDNs) represent a major investment for water supply systems development. The standard procedure for their design is to search for the minimum cost, which is produced by the smaller diameters capable of maintaining the minimum required pressure. However, some District Metered Areas (DMAs) have a significant topographic elevation difference, and even if the minimum diameters are reached, the pressure remains high, and a Pressure Reducing Valve (PRV) is necessary. However, if the pipe diameters of the network are increased, distributed headloss will be reduced, and this additional energy will be locally dissipated in PRVs to maintain the pressure in the DMA below the maximum allowed value. If a turbine is installed instead, the dissipated energy can be used, creating a benefit that can justify the additional investment due to the diameter increment. Therefore, this paper presents a method for the optimal design of a WDN considering energy recovery. The use of Pumps as Turbines (PATs) is considered for energy production. The optimal design is obtained using a two-level optimization procedure: the first is used to obtain pipe diameters, and the second is used for PAT selection. Particle Swarm Optimization is used, and two case studies are presented.

Electrical behaviour of the pump working as turbine in off grid operation

The use of pumps working as turbines (PATs) connected to the electric system, in the replacement of pressure reduction valves to reduce the excessive pressure in water distribution networks, have been studied for the last years. The introduction of PATs is very important in the water-energy nexus to promote the increase of the energy savings. As consequence, the majority of the water systems does not have access to the electrical grid and, therefore, the need to study the PATs operation off-grid is necessary. In this line, the novelty of this research is the application and optimization of a PAT in water systems when the recovery solution is off-grid type. To operate correctly, the induction machine requires an external source of reactive power, which is typically provided by the electrical grid. To supply the required reactive power, a bank of capacitors is installed at the machine terminals, so-called self-excited induction generator (SEIG). The analytical model, simulation and experimental works were performed, to analyse the SEIG behaviour. The results were applied in a SEIG-PAT system obtaining the global efficiency of the system for different speeds and loads. The global efficiency decreases 47% when off-grid operation, showing the need to optimize the electrical parameters of the generator to operate as off- grid with acceptable efficiency levels. In this framework, a tuning methodology for the SEIG capacitor bank values was developed to be automatically adjusted according to the operating point of the PAT to maximize its efficiency.

Hydraulic characterization and transient response of pressure reducing valves: laboratory experiments

Abstract A pressure reducing valve (PRV) regulates the outlet pressure regardless of the fluctuating flow and varying inlet pressure, thereby reducing leakage and mitigating the stress on the downstream water distribution network (WDN). Notwithstanding the crucial importance of PRVs, few experimental data are available in the literature. The aim of this paper is to overcome this gap by means of the results of a large number of tests carried out at the Water Engineering Laboratory of the University of Perugia, Italy. These tests have been executed on a standard type of PRV in steady-state conditions, to characterize it, and in unsteady-state conditions, to check its transient response. A broad range of laboratory conditions simulating possible events in WDNs has been examined and both short and long duration monitoring have been carried out. The analysis of the tests demonstrates the versatility of PRVs as a powerful tool for pressure management, and also when the flow condition changes according to the users' demand pattern. In fact, their transient response is appropriate with small pressure oscillations generated by the PRV self-adjustment. Moreover, proper PRV modelling has to include both its mechanical behaviour and the characteristics of the pressure pipe system in which it is installed.

Pressure management and energy recovery in water distribution networks: Development of design and selection methodologies using three pump-as-turbine case studies

Energy consumption in water distribution networks is a widely publicised problem. Similarly the control of leakage through pressure management in water networks has also received significant attention in the literature. This paper outlines progress on the development of micro-hydropower systems for energy recovery and pressure management in water distribution networks.Design and selection methodologies are outlined for pump-as-turbines (PAT) to recover energy and control pressure at 3 case study pressure reducing valves (PRV) in the water distribution network (WDN) of Dublin, Ireland. This investigation comprised the use of experimental characterisation of a laboratory scale prototype PAT, extrapolation of these results to larger scales using Suter and Affinity laws, and the assessment of their performance against real-world flow and pressure data. An assessment of existing PAT selection methodologies was also conducted and compared against the experimental data.The results of this investigation highlight that up to 40% of the gross power potential of an existing PRV could be converted to electrical energy using a PAT while also controlling pressure. Existing PAT selection methodologies did not concur well with the experimental results. The use of 2 PATs in parallel to increase the efficiency of the overall system achieved marginal improvements in performance.

Pressure control for minimizing leakage in water distribution systems

In the last decades water resources availability has been a major issue on the international agenda. In a situation of worsening scarcity of water resources and the rapidly increasing of water demands, the state of water losses management is part of man’s survival on earth. Leakage in water supply networks makes up a significant amount, sometimes more than 70% of the total water losses. The best practices suggest that pressure management is one of the most effective way to reduce the amount of leakage in a water distribution system. The approach presented in this study is aimed at modeling leakage as a function of pressure and pipe length, calibrating leakage coefficient, using fixed pressure reducing valves (PRVs) to develop pressure fluctuation and developing WaterCAD scenarios to minimize leakage through the most effective settings of PRVs. This approach was applied on a district metered area (DMA) in Alexandria, Egypt. The application of this approach produced some encouraging results, where the leakage through DMA was dropped by 37% for the best scenario. Thus, this approach is recommended as a decision support tool for determining a desirable solution for leakage reduction.

A Comparison of Prediction Methods for Design of Pump as Turbine for Small Hydro Plant: Implemented Plant

In developing countries, small and micro hydropower plants are very effective source for electricity generation with energy pay-back time (EPBT) less than other conventional electricity generation systems. Using pump as turbine (PAT) is an attractive, significant and cost-effective alternative. Pump manufacturers do not normally provide the characteristic curves of their pumps working as turbines. Therefore, choosing an appropriate Pump to work as a turbine is essential in implementing the small-hydro plants. In this paper, in order to find the best fitting method to choose a PAT, the results of a small-hydro plant implemented on the by-pass of a Pressure Reducing Valve (PRV) in Urmia city in Iran are presented. Some of the prediction methods of Best Efficiency Point of PATs are derived. Then, the results of implemented project have been compared to the prediction methods results and the deviation of from measured data were considered and discussed and the best method that predicts the specifications of PAT more accurately determined. Finally, the energy pay-back time for the plant is calculated.