Feed Water Flow Rate Research Articles

Measurement of Feedwater Flow Rate of Nuclear Power Plant Reactors

Procedural, technical and operational difficulties that arise with the use of flowmeters, both ultrasonic flowmeters and flowmeters constructed with the use of constriction devices (orifice-based flowmeters), for measuring feedwater flow rates at nuclear power plant reactors are considered. Results of measurements of these flowmeters are used to calculate the thermal power of the reactor plant and are important for controlling the nuclear reactor. It is shown that periodic inspection of welded-in orifice devices used at nuclear power plants of Russian design is not possible. Practical aspects of tests of ultrasonic flowmeters under normal conditions with assigned high precision for operation under the conditions of a power-generating unit are considered. New approaches to evaluation (inspection) of the state of constriction devices used in cooling agent flowmeters that are not accessible to examination throughout the entire operating period at nuclear power plants are proposed. It is shown that a method of direct comparison of the results of simultaneous measurements with a more precise mobile ultrasonic flowmeter may be used to estimate the error of flowmeters constructed with the use of constriction devices. A unified method is suggested for evaluating the state of constriction devices without dismantling the devices from the pipeline based on information on the total error of the flowmeters along with a complex of measures for the development of technical, procedural, and managerial means of controlling the reliability of flowmeter measurements with the use of constriction devices and ultrasonic and flowmeters.

Removal and recovery of phosphorus from low-strength wastewaters by flow-electrode capacitive deionization

Phosphorus (P) concentrations as low as 10 mg/L P can lead to eutrophication in natural waters. Meanwhile, phosphorus is an important and non-renewable resource for humans, animals and plants. This study investigated the removal and recovery of phosphorus from low-strength wastewaters by flow-electrode capacitive deionization (FCDI) to realize the sustainable utilization of phosphorus. Effects of different operating parameters on the performance of FCDI for phosphorus removal were systematically studied, including applied voltage, flow rate and flow direction of feed water, initial phosphorus concentration, carbon black content and initial pH value. Results showed that the applied voltage and initial pH value had great influence on the phosphorus removal efficiency. The removal efficiency of phosphorus reached about 97% when the operating parameters were optimized. The FCDI system possessed good removal performance of phosphorus after six consecutive cycling tests. In addition, the low concentration of feed phosphorus solution (100 mg/L P) could be effectively concentrated by 16 times after 11 h of operation through the enrichment experiment, leading to a final concentration of 16.8 mg/L P in feed solution and 1567 mg/L P in the aqueous phase of flow electrodes. To conclude, these results revealed that FCDI system is effective in phosphorus removal and recovery, and has great application prospects in treatment of phosphorous wastewaters.

Experımental investigation of heat pump driven humidification-dehumidification desalination system for water desalination and space conditioning

This work presents an experimental investigation of the performance of a HDH system operated by heat pump. The novel heat pump system provides the necessary heating for the humidifier and cooling for the dehumidifier of the HDH system. The proposed integrated unit is capable of producing freshwater as well as cooling effect for space conditioning through water heated or cooled heat exchange units. Influence of various operating parameters such as feed water flowrate, feed water temperature and chilled water flowrate on the general assessment metrics, including gain output ratio (GOR), recovery ratio (RR), coefficient of performance (COP), energy utilization factor (EUF), Specific electrical energy consumption (SEEC) and productivity are evaluated. The cost of freshwater production from the proposed desalination unit is estimated. Results showed that the integrated system is capable of attaining maximum GOR of 4.07, RR of 4.86%, COP of 4.85, EUF of 3.04, and productivity of 287.8 L/day. The minimum SEEC of the system was found to be 160.16 kWhr per cubic meter of freshwater. The system is also capable of providing cooling load of 3.07 kW while producing the needed desalinated water. The estimated price of freshwater production varied from 10.68 US$ to 20.39 US$ per cubic meter.

Investigation and Improvement of the Humidification–Dehumidification Solar Water Desalination System Implemented Wick as Packing Material

Abstract In this work, a humidification–dehumidification unit powered by solar energy was designed, constructed, and tested for brackish water desalination. In order to enhance the mass and heat transfer between feedwater and flowing air, 16 layers of wick were used as packing material. The results showed that the daily productivity increased by 28.28% when wick was used. The desalination unit with wick was tested at different temperatures and flowrates of feedwater. High significance positive relation between productivity and feedwater flowrate was found. The proposed system was also tested at a wide range of air flowrate. The results also showed that the peak value of productivity was achieved when the air flowrate was 0.0075 kg/s. It was also found that the daily productivity increased by 31.3% when the feedwater flowrate was increased from 0.114 to 0.171 kg/s when the air flowrate was 0.0075 kg/s.

Optimum arrangement of two-stage plug and concentrate recycling RO systems using thermodynamic and exergy analysis

Purpose This paper aims to determine the optimum arrangement of a reverse osmosis system in two methods of plug and concentrate recycling. Design/methodology/approach To compare the optimum conditions of these two methods, a seawater reverse osmosis system was considered to produce fresh water at a rate of 4,000 m3/d for Mahyarkala city, located in north of Iran, for a period of 20 years. Using genetic algorithms and two-objective optimization method, the reverse osmosis system was designed. Findings The results showed that exergy efficiency in optimum condition for concentrate recycling and plug methods was 82.6 and 92.4 per cent, respectively. The optimizations results showed that concentrate recycling method, despite a 36 per cent reduction in the initial cost and a 2 per cent increase in maintenance expenses, provides 6 per cent higher recovery and 19.7 per cent less permeate concentration than two-stage plug method. Originality/value Optimization parameters include feed water pressure, the rate of water return from the brine for concentrate recycling system, type of SW membrane, feedwater flow rate and numbers of elements in each pressure vessel (PV). These parameters were also compared to each other in terms of recovery (R) and freshwater unit production cost. In addition, the exergy of all elements was analyzed by selecting the optimal mode of each system.

Performance enhancement of a multi-effect desalination plant: A thermodynamic investigation

In current work the multi-effect desalination (MED) plant scheme and operation have been studied based on thermodynamic optimization using mathematical calculation and modeling for the main equations related to mass, energy and salinity balance taking in account the synchronized consequence of several constraints on the system execution. The effects of irreversibilities and energy losses are integrated in the study which in turn the results obtained are very close to the real results more than previous studies. The results obtained show that the system performance is meaningfully influenced by heat source flux, stage number, heat exchangers efficiency and feed water temperature and flow rate Then the effects of involved parameters are performed and discussed. Moreover, various 3D results have been displayed involving the effect of more than two parameters in system performance. Therefore, the outputs of this work assist manufacturer for the optimization and design of MED plant. The authenticity and perfection of the numerical solution technique are proved and verified within real results.

Two-Phase Flow Analysis and Design of Geothermal Energy Turbine

A two-phase geothermal turbine generates mechanical energy by means of a total flow system. Literature references are available for experimental investigation of such flow machines but there is no validated numerical model for prediction of flow field and flashing for optimal design of the turbine’s flow channels. This paper presents a test reaction-turbine design study with two-phase flow using CFD. An Eulerian-Eulerian multiphase model with the Thermal Phase-Change criteria for two-phase heat, mass and momentum transfer has been used. Phase change validation has been conducted on published experimental data on a converging-diverging nozzle flow at various operating conditions. The stationary nozzle model was then extended to curved nozzle turbine and the results of flow and power has been validated with the data available in literature. Liquid water and vapour distribution due to flash evaporation was predicted by the analysis. Two-phase turbine model so established has been used further to re-design and optimise turbine nozzle by evaluating its cross section, area ratio, throat design, specific torque variation and curvature. Two new channel geometries, square and blended, were compared with the base circular channel and it was found that a blended channel offers on an average 6% higher specific power at 4623rpm. For the same rotor diameters and feed water flow rate, the power output could thus be improved by 4.5%. Isentropic efficiency in the range of 10 to 19% was estimated. Final design will be prototyped and tested in the laboratory for validation of design and deployment in eastern Africa.

Practical dynamic matrix control of MHTGR-based nuclear steam supply systems

To balance the intermittent renewable energy and cope with the increasing nuclear power installed capacity in China, it is necessary for nuclear power plants (NPPs) to operate with load-following mode for enhancing economic competitiveness. The modular high temperature gas-cooled reactor (MHTGR) is an appropriate candidate for load-following operation due to the advanced features such as robust fuel elements, online fueling and full-power-range temperature negative feedback. The MHTGR-based nuclear steam supply systems (NSSS) which produces superheated steam flow for electricity, is the core for any NPPs. The proper control of NSSS is the prerequisite for the safe, stable and efficient load-following operation. However, in current engineering practice, the set-point trajectories of neutron flux, primary coolant temperature, primary and secondary flowrates are just the curves by linking the referenced steady values from the thermal hydraulic design, which are further determined by the thermal power requirement. Thus, it is meaningful to investigate an optimization-oriented control method to improve the operation efficiency. Motivated by this, two dynamic matrix control (DMC) with cascade structure are presented to improve both thermal power and steam temperature of the MHTGR-based NSSS. The thermal power is optimized by the first DMC through adjusting the set-point of nuclear flux. The second DMC is then designed based on the integration of the NSSS, the proportional-integral-derivative (PID) and the first DMC to improve the steam temperature response by adjusting the feed-water flowrate. The control performance during wide range operation is shown and discussed with the simulation results of a large-scale MHTGR plant model.

Development of thermal-hydraulic analysis code of a helically coiled once-through steam generator based on two-fluid model

A thermal-hydraulic analysis model, coupling the flow and heat transfer of the primary and secondary sides, is developed to describe the thermal hydraulic behavior of OTSG (helically coiled Once-Through Steam Generator). This numerical model is developed based on the two-fluid model with distributed parameters method to predict all flow variables at each position along the tube. Correlations, validated a lot, are adopted to consider the effect of helical structure on the flow and heat transfer of both the primary and secondary sides in OTSG. The computational code THOSG (Thermal-Hydraulic analysis code of Once-through Steam Generator) for OTSG is then developed based on the numerical model with the modified SIMPLE algorithm. To benchmark the developed physic model and computer code, steady-state simulation of OTSG of IRIS reactor is conducted. Results are compared with RELAP5 code with respect to the design parameters. Comparisons indicate that the THOSG code can predict the thermal-hydraulic characteristics of OTSG well. In order to investigate the effect of changes in the input conditions on the output of the OTSG, transient analysis has been performed. Simulations of change in feedwater flow rate and temperature are conducted to assess the performance of OTSG. Both steady-state and transient results indicate that the THOSG code can be utilized for the design and performance analysis of OTSG. However, further analysis, coupling with the thermal-hydraulic behavior of the reactor core, is required to comprehensively evaluate the safety and reliability of OTSG design in nuclear power plant.

Economic analysis for process optimization of Chabahar Maritime University reverse osmosis desalination plant: a case study

Seawater desalination is a way ahead to produce tap water in the Iranian coastline of the Oman sea with arid climate. The Chabahar Maritime University (CMU) desalination plant which its prototype was launched in 1994, currently using the reverse osmosis (RO) membranes is producing fresh water with a capacity of 336 m3/day and TDS of 400. Here, it is attempting to draw the plant overall scheme and to produce the technical documents of its constituent parts. An experimental study was conducted to estimate the current working conditions of this RO desalination site, and a simple formulation method using by Microsoft Excel 2010 is developed to model and optimize the cost and processing parameters such as active surface area of the membrane in the RO desalination plant. The mode of site’s economic estimation provides a way to find the optimal working conditions including feed flow rate, recovery ratio and so on. The results indicate that with some small adjustments in the process, the cost of water can be dramatically reduced. For example, with an increase in the flow rate of the intake feed water from 840 to 5784 m3/day, cost of product water reduces from 2.2 $/m3 to 1.4 $/m3.

Controller design using quantitative feedback theory for thermal power plant process

This paper proposes a controller design that is robust to parameter variations occurring in a Thermal Power Plant Process. Real time cold startup data is collected from NLC Tamilnadu Power Limited (NTPL), Tuticorin unit, of 500 MW capacity. This data is used for modelling the coal flow rate, air flow rate and feed water flow rate loops which will be controlled to ultimately control the generated electric power. Quantitative Feedback Theory is a technique used for controller design, obtaining the parameters of the PD controller that promotes robustness in the specified performance even with variations in the plant parameters. For a particular frequency, the magnitude and phase of the open loop gain and phase curve are acquired and solving the resultant equations confers us the tuning parameters of the controller. From the simulation results, it can be highlighted that the controller performs fairly well.

Investigation of Efficiency of Magnetic Separation Methods for Processing of Low-Grade Iron Pigments Ore (RED Ochre)

In this research, the efficiency of magnetic separation methods for processing of a low-grade iron pigments ore (red ochre) has been studied. Based on the mineralogical analyses (XRD), thin section and polish studies, the reserve is an iron sedimentary deposit with an average Fe grade of %31.3. The most valuable minerals are Hematite and Goethite and main gangue minerals are Calcite and Quartz. Wet and dry high-intensity magnetic separation methods were applied for processing. The full factorial design was implemented for all of the wet high-intensity magnetic separation (WHIMS) experiments. Factors of magnetic field intensity, rotor speed and feed water flowrate were considered for design. In optimal conditions in rougher stage, WHIMS produced a concentrate with grade %42.92 Fe and recovery %62.23 in magnetic field intensity 1.7 Tesla, feed water flowrate 5 liter per minute and speed of rotor 3 rounds per minute; also after two stage cleaning WHIMS produced a concentrate with Fe grade and Fe recovery of %56.12 and %38.56, respectively. The results of the dry high-intensity magnetic separation for the two coarser fractions showed that size fraction of coarser than 1000 micron produced a concentrate with Fe grade %40.32 and relative Fe recovery %95.11 and size fraction of -1000+150 micron with Fe grade %45. 04 and relative Fe recovery %75.14. The results of experiments show that there is a low capability for improving quality and grade of this ore. Achieved concentrate from experiments could be used as an initial feed of producing pigment.

An optimization of the components and operating conditions of a pre-cooling system for tubular ice making machines

The mathematical models were developed to optimize the components and the operating conditions of a pre-cooling system for the conventional tubular ice production. The system can be simultaneously used with up to three ice making machines. The water used to feed into the machines is pre-cooled by circulating through a heat exchanger to transfer its heat to the chilled water circulating from a water chiller. Four ice machine capacities, 40, 50, 60 and 90 ton/day, were investigated. It was found that NTU=3 was the optimum heat exchanger capacity, the feed water flow rate to chilled water flow rate ratio of 0.5 and the feed water flow rate of 0.12 m3/min are the optimum operating conditions. The ice productivity was increased by the system. It increased with the machine capacity and the number of machines operating with the system. The increases in the productivity were in the range of 7,398-18,851 kg/day.

Stability analysis on flow parameters in coolant temperature control system of lead-cooled fast reactor

Lead-cooled Fast Reactor (LFR), one of the promising nuclear energy technologies for future advanced system, is well foreseen in meeting the goals of Generation IV fission reactor. In LFR, Coolant Temperature Control System (CTCS) is one of the critical parts, and the influence of coolant flow parameters on the stability analysis is worth investigating and studying. In this paper, we use the CLEAR-S, an integrated multifunctional non-nuclear test facility, as reference and the stability analysis of CTCS, concerned to coolant flow rate has been completed based on simplified coolant thermal circulation model. Location of eigenvalues and calculation results of real stability radius, both qualitatively and quantitatively reflect the influence of coolant flow rate on stability respectively. The analysis results show that the feed-water flow rate in steady state is a critical parameter for CLEAR-S, because larger feed-water flow rate can improve stability apparently. However, LBE coolant flow rate has little impact on system stability. The results of this work will provide an effective reference for design and operation of LFR.

A master-slave control strategy of the multi-modular SMR

Small modular reactor (SMR) is a type of advanced reactor depending on its inherent safety, good economic performance, and multipurpose. SMR always adopts the multi-modular layout, which uses several nuclear steam supply systems (NSSSs) to supply steam to a common steam header. A pressurized water reactor (PWR) type multi-modular SMR (MSMR) system is studied in this paper. Due to the operation demands of continuity and flexibility during load following, a proper control strategy and operation scheme of the MSMR must be investigated.A master-slave control strategy is proposed for steam flow sharing control of the MSMR systems. Under the proposed control strategy, one of the NSSS modules is selected as the master control channel, and its feed water flow rate is regulated using the steam header pressure error. The remaining NSSS modules are treated as the slave channels. The feed water flow rate of the master channel is utilized to slave the other channels, which are flow-controlled.Three operation schemes are set according to different operation demands. (1) Equilibrium Scheme (EquS), in which every module undertakes the same load during the load following operation. (2) Non-equilibrium Scheme (NEquS), in which every module undertakes the different loads during the load following operation. This operation scheme manages more modules operate at full power to ensure its economy and operation simplicity. (3) Constant Output Scheme (ConS), which is mainly used during refueling or maintenance process. When one module is disturbed, other modules undertake its load to ensure the total power output constant. Based on these schemes, four typical operation cases are defined and simulated.Through the analysis of the simulation results, the suitable operation conditions for these operation schemes are suggested, and the relevant control strategy is verified.

Transient safety analysis of M2LFR-1000 reactor using ATHLET

Abstract M2LFR-1000 is a medium-power modular lead-cooled fast reactor, developed by University of Science and Technology of China (USTC), aiming at achieving a reactor design fulfilling the Gen IV nuclear system requirements and meanwhile emphasizing the optimum safety and economics. In order to evaluate the safety performance of M2LFR-1000 reactor core, three typical transients are selected from initiating events, which are unprotected transient overpower (UTOP), unprotected loss of offsite power (ULOHS+ULOF) and increase of feedwater flowrate with primary pumps trip (IFW+PLOF). These three transients presented and discussed in this paper are performed with the code Analysis of THermal-hydraulics of LEaks and Transients (ATHLET), which is developed by Gesellschaft fur Anlagen-und Reaktorsicherheit gGmbH (GRS). The results indicate that the M2LFR is safe enough under these three transients due to the good inherent safety features of the reactor, without human intervention, the reactor will reach a new steady state under UTOP condition.

The Challenging Thermophysical Issues of Fast Reactors

The article presents and analyzes the results from topical thermophysical investigations aimed at substantiating the characteristics and assessing the safety of liquid metal cooled fast reactors: an advanced largecapacity fast sodium-cooled reactor and a fast lead-cooled reactor. We also outline the results from experimental investigations into hydrodynamics and heat transfer for stratified flow of coolant, into thermal hydraulics of a large-modular “sodium–water” steam generator in different modes of reactor operation, and into the fuel assembly degradation process in the course of a severe accident involving loss of sodium flowrate in a fast reactor. The basic mechanisms governing degradation of dummy fuel rod claddings are identified; the distribution of marker materials over the fuel assembly height in its ultimate state is estimated, and the phenomena of blocking the fuel assembly flow pass section and the marker materials being thrown to beyond the assembly boundaries are studied. The article demonstrates the advisability of using a combined sodium purification system built into the reactor vessel that contains cold traps as a mandatory element along with hot traps, which serve to perform accelerated removal of oxygen during the NPP operation at its nominal parameters. The results from thermal–hydraulic tests of the lead-cooled reactor core carried out on the 6B experimental setup and of the steam generator carried out on the SPRUT experimental setup installed at the SSC RF–IPPE are presented.1 It has been found from the experiments on the thermal–hydraulic model of the lead-cooled reactor’s steam generator that the steam temperatures at the outlets from both headers are identical with each other and so are the lead temperatures at the downcomer section outlet and in the main lead path. The experiments did not show pulsations of feedwater flowrate or pressure in the loops, which points to the stable nature of operation at partial load. The state of the technology of heavy metal coolants and the prospects for its future development are considered. It is shown that there is a possibility in principle to realize the required parameters of a high-temperature sodium-cooled fast reactor for producing large quantities of hydrogen, e.g., based on one of the thermochemical cycles or high-temperature electrolysis with a high electricity thermal utilization factor. The problems that must be solved during the further thermophysical investigations are analyzed.

Control of electric power generation of thermal power plant in TamilNadu

A control configuration for controlling the generated power in NLC TamilNadu Power Limited (NTPL) thermal power station by manipulating the coal flow rate, air flow rate and feed water flow rate is proposed here. Real Time data from NTPL thermal power station unit-Tuticorin unit of 500 MW capacity is recorded over an interval of time. This real-time data is used to model the coal flow rate, air flow rate and feed water flow rate loops which will be controlled to eventually control the generated power. The controller for the three loops is tuned using evolution and optimization techniques like genetic algorithm (GA) and Particle Swarm Optimization (PSO). Results of the controller tuned using both the techniques are provided and they are compared with each other. From the simulation results, it can be emphasized that the controller performs fairly well in servo and regulatory configurations.

On the feasibility and possibility of heating water for district heating systems through the use of heat of the main condensate after cogeneration turbines

The possibilities of increasing the efficiency of cogeneration turbines of CHP plants through the use of low-potential heat carriers for water heating in district heat supply systems and increasing the generation of CHP electricity are considered. The existing technologies of heating the makeup water of the district heating system upstream water treatment apparatuses do not always provide the required heating temperature and do not have the sufficient energy efficiency. The technologies of using the main condensate of the exhaust steam in the turbine to heat the feed water in additional heaters included in the system of regeneration of cogeneration turbines are developed. The use of these technologies contributes to increasing the flow rate and reducing the enthalpy of the steam of regenerative outlets of the turbine used to heat this condensate, and, therefore, increases the combined heat and power generation. In order to determine the industrial applicability of the proposed solutions, experimental studies of the regeneration systems of turbo-units under the conditions of Ulyanovsk СHPPs-1 have been carried out. Multiparameter data arrays on operation of turbine condensate-feed path have been collected, and regression equations have been obtained to calculate the main condensate flow temperatures depending on various factors. On the basis of experimental data there have been calculated the minimum and maximum flow rates of feed water that can be heated to the desired temperature in the surface heaters included in the regeneration system of the turbines, the flow graphs of the heated feed water are constructed depending on the temperature of the main condensate after the turbines. The fields of application of the proposed technological solutions in operating heat supply systems are defined. The evaluation of energy efficiency is carried out using the method of specific generation of CHP electricity and conventional fuel economy at the implementation of the proposed solutions is calculated.

Dynamic simulation of a heat recovery steam generator dedicated to a brine concentration plant

Considering water level and pressure variation in drum of a natural circulation heat recovery steam generator (HRSG) is very crucial to design HRSGs; in other words, if a sudden change occurs in input heat rate, steam and feed water flow rate, drum water level would increase or decrease rapidly. Therefore, due to their important role, drum inlet parameters, such as steam quality and pressure should be accurately controlled. In this study, a dynamic simulation of HRSG was carried out to investigate dynamic behavior of important key parameters involved in the steam generating process. The rate of produced pure water by brine concentration plant under varying gas turbine load and consequently input heat rate to the HRSG’s risers was investigated as well. Results showed that a rapid increase in input heat rate to the tube bundle increases evaporation rate and intensely increases steam quality as a result; therefore, too much excess heat could increase the chance of tube failure. Moreover, drum pressure drop and reduction in system water volume were occurred due to the increase in steam demand. By increasing input heat rate about 20%, the risers’ outlet steam quality increased significantly almost 45% of initial steam quality. In addition, a 5% increase in input heat rate led to approximately 20% growth in generated steam pressure, causing a more motive steam of higher quality being injected into the brine concentrator and finally generating 2% more pure water flow rate as a result.