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Markov approach to evaluate the availability simulation model for power generation system in a thermal power plant ,
Ravinder Kumar,Avdhesh Kr. Sharma,P.C Tewari
International Journal of Industrial Engineering Computations , 2012,
Abstract: In recent years, the availability of power plants has become increasingly important issue in most developed and developing countries. This paper aims to propose a methodology based on Markov approach to evaluate the availability simulation model for power generation system (Turbine) in a thermal power plant under realistic working environment. The effects of occurrence of failure/course of actions and availability of repair facilities on system performance have been investigated. Higher availability of the components/equipments is inherently associated with their higher reliability and maintainability. The power generation system consists of five subsystems with four possible states: full working, reduced capacity, reduced efficiency and failed state. So, its availability should be carefully evaluated in order to foresee the performance of the power plant. The availability simulation model (Av.) has been developed with the help of mathematical formulation based on Markov Birth-Death process using probabilistic approach. For this purpose, first differential equations have been generated. These equations are then solved using normalizing condition so as to determine the steady state availability of power generation system. In fact, availability analysis is very much effective in finding critical subsystems and deciding their preventive maintenance program for improving availability of the power plant as well as the power supply. From the graphs illustrated, the optimum values of failure/repair rates for maximum availability, of each subsystem is analyzed and then maintenance priorities are decided for all subsystems.The present paper highlights that in this system, Turbine governing subsystem is most sensitive demands more improvement in maintainability as compared to the other subsystems. While Turbine lubrication subsystem is least sensitive.
Study of a Multivariable Coordinate Control for a Supercritical Power Plant Process
International Journal of Energy Engineering , 2012, DOI: 10.5923/j.ijee.20120205.04
Abstract: the paper presents our recent research work in study of a novel multivariable coordinate control for a 600MW supercritical (SC) power plant process. The nonlinear mathematical model of the plant is briefly described in the paper. Then, a control strategy is designed which is based on Generalized Model Predictive Control (MPC) theory and tested within small load changes. But the MPC alone performs well only within small load changes even with consideration of constant disturbance and measurement noises in prediction algorithm. We then propose a dynamic compensator in parallel with the MPC to track large load changes. Because the model has been identified with on-site closed loop data, the multivariable optimal control signals have been used as a correction to the reference of the plant local controls instead of direct control signal applications. The simulation results have shown good performance of the controller in response to some load changes. Furthermore, it has been proved that the plant dynamic response can be improved by increasing the coal grinding capability and pulverized coal discharging through the implemented coal mill controllers. The benefit from this study is to provide convinced methodology to improve the SC power plant dynamic response for fulfilment of National Grid Code (NGC) requirements.
International Journal of Electrical, Electronics and Data Communication , 2013,
Abstract: For the continuous evaluation of the performance of the power system, power flow solutions are essential for exhibiting suitable control actions in case of requirement. This case study presents analysis of the electrical power system of continuous process plant having its own captive generation along with the provision of the Grid connectivity. The different power system elements are modeled as per the manufacturer’s data sheet. To evaluate the steady state performance, power flow simulations and analysis of the complex power system for various invasive operating conditions are carried out.
Reduction In Parasitic Load In A Solar Thermal Power Plant To Improve Its Efficiency  [PDF]
Neha Jain
International Journal of Scientific Research and Reviews , 2013,
Abstract: Rapid development in technology and improvement in life style of present generation has caused anincreased dependence on electricity and hence on sources of energy which are unfortunately, nonrenewable.The present world is looking up at renewable sources of energy to combat looming energycrisis. This is necessitated not only due to depleting non renewable sources, but also due to increasedCO2 content and consequent global warming. So far solar energy has been looked upon as the mostideal alternative source of energy. The reason behind this is the abundance of solar energy coupledwith a large number of ways in which it can be harnessed for purposes such as heating, drying or forgenerating electricity. For large scale electricity generation with high degree of efficiency, solarthermal power is considered a better option over photo-voltaic. A few projects worldwide are operatingand many are in different stages of construction in different parts of the world. As a learningtechnology, a large magnitude of research work over improvement in this technology is also going on.One challenge faced by industry is to reduce the parasitic load involved in generation of electricity inthese plants. The parasitic load contributes in reducing the system efficiency and needs to be eliminatedor minimized. The present paper investigates the causes of parasitic load in a solar thermal plant andtries to find out ways of its reduction.
A cyclic time-dependent Markov process to model daily patterns in wind turbine power production  [PDF]
Teresa Scholz,Vitor V. Lopes,Ana Estanqueiro
Statistics , 2013,
Abstract: Wind energy is becoming a top contributor to the renewable energy mix, which raises potential reliability issues for the grid due to the fluctuating nature of its source. To achieve adequate reserve commitment and to promote market participation, it is necessary to provide models that can capture daily patterns in wind power production. This paper presents a cyclic inhomogeneous Markov process, which is based on a three-dimensional state-space (wind power, speed and direction). Each time-dependent transition probability is expressed as a Bernstein polynomial. The model parameters are estimated by solving a constrained optimization problem: The objective function combines two maximum likelihood estimators, one to ensure that the Markov process long-term behavior reproduces the data accurately and another to capture daily fluctuations. A convex formulation for the overall optimization problem is presented and its applicability demonstrated through the analysis of a case-study. The proposed model is capable of reproducing the diurnal patterns of a three-year dataset collected from a wind turbine located in a mountainous region in Portugal. In addition, it is shown how to compute persistence statistics directly from the Markov process transition matrices. Based on the case-study, the power production persistence through the daily cycle is analysed and discussed.
Comparison of Risk Assessment for a Nuclear Power Plant Construction Project Based on Analytic Hierarchy Process and Fuzzy Analytic Hierarchy Process  [PDF]
Dae-Woong Shin, Yoonseok Shin, Gwang-Hee Kim
Journal of Building Construction and Planning Research (JBCPR) , 2016, DOI: 10.4236/jbcpr.2016.43010
Abstract: Recently, plant construction throughout the world, including nuclear power plant construction, has grown significantly. The scale of Korea’s nuclear power plant construction in particular, has increased gradually since it won a contract for a nuclear power plant construction project in the United Arab Emirates in 2009. However, time and monetary resources have been lost in some nuclear power plant construction sites due to lack of risk management ability. The need to prevent losses at nuclear power plant construction sites has become more urgent because it demands professional skills and large-scale resources. Therefore, in this study, the Analytic Hierarchy Process (AHP) and Fuzzy Analytic Hierarchy Process (FAHP) were applied in order to make comparisons between decision-making methods, to assess the potential risks at nuclear power plant construction sites. To suggest the appropriate choice between two decision-making methods, a survey was carried out. From the results, the importance and the priority of 24 risk factors, classified by process, cost, safety, and quality, were analyzed. The FAHP was identified as a suitable method for risk assessment of nuclear power plant construction, compared with risk assessment using the AHP. These risk factors will be able to serve as baseline data for risk management in nuclear power plant construction projects.
Integrative Approach to the Plant Commissioning Process  [PDF]
Kris Lawry,Dirk John Pons
Journal of Industrial Engineering , 2013, DOI: 10.1155/2013/572072
Abstract: Commissioning is essential in plant-modification projects, yet tends to be ad hoc. The issue is not so much ignorance as lack of systematic approaches. This paper presents a structured model wherein commissioning is systematically integrated with risk management, project management, and production engineering. Three strategies for commissioning emerge, identified as direct, advanced, and parallel. Direct commissioning is the traditional approach of stopping the plant to insert the new unit. Advanced commissioning is the commissioning of the new unit prior to installation. Parallel commissioning is the commissioning of the new unit in its operating position, while the old unit is still operational. Results are reported for two plant case studies, showing that advanced and parallel commissioning can significantly reduce risk. The model presents a novel and more structured way of thinking about commissioning, allowing for a more critical examination of how to approach a particular project. 1. Introduction 1.1. Background Plant modifications are an ongoing process throughout the life of any process plant. Reasons for modification include efforts to improve reliability, production capacity, quality, or productivity. Seamless incorporation is the key concern associated with the installation of any new equipment in an operating plant due to the high cost of process downtime. Several steps can be taken to minimise the risk associated with the installation of new equipment such as hazard and operability studies, project management, development of redundancy plans, and commissioning of the new equipment. Of these, commissioning is an essential activity in many plant-modification projects and has significant implications for project success. Yet paradoxically it tends to be approached in an ad hoc manner. It is often included in project plans, so it is not that people are ignorant of commissioning. Rather, the problem is that there is a lack of systematic approaches to commissioning, so it is frequently left to tradespeople and plant operators to manage in whatever way they see fit. This is an undesirable situation since it results in unpredictable outcomes. In some cases it can even cause serious problems. An extreme example would be the catastrophic failure of the Chernobyl nuclear power plant (1986), which was caused by operators attempting an ad hoc test of the efficacy of a modified emergency cooling system. This paper presents a structured conceptual model for the commissioning process, and two cases studies showing application to operating plant. 2.
Process Simulation of a 620 Mw-Natural Gas Combined Cycle Power Plant with Optimum Flue Gas Recirculation  [PDF]
Ahmed Badr Al Hashmi, Abdel Aziz Abdulla Mohamed, Zin Eddine Dadach
Open Journal of Energy Efficiency (OJEE) , 2018, DOI: 10.4236/ojee.2018.72003
Abstract: The main objective of this investigation is to obtain an optimum value for the flue gas recirculation ratio in a 620 MW-Natural Gas Combined Cycle (NGCC) power plant with a 100% excess air in order to have a composition of the exhaust gas suitable for an effective absorption by amine solutions. To reach this goal, the recirculated flue gas is added to the secondary air (dilution air) used for cooling the turbine. The originality of this work is that the optimum value of a Flue Gas Recirculation (FGR) ratio of 0.42 is obtained from the change of the slope related to the effects of flue gas recirculation ratio on the molar percentage of oxygen in the exhaust gas. Compared to the NGCC power plant without flue gas recirculation, the molar percentage of carbon dioxide in the flue gas increases from 5% to 9.2% and the molar percentage of oxygen decreases from 10.9% to 3.5%. Since energy efficiency is the key parameter of energy conversion systems, the impact of the flue gas recirculation on the different energy inputs and outputs and the overall efficiency of the power plant are also investigated. It is found the positive effects of the flue gas recirculation on the electricity produced by the steam turbine generator (STG) are more important than its cooling effects on the power output of the combustion turbine generator (CTG). The flue gas recirculation has no effects on the water pump of the steam cycle and the increase of energy consumed by the compressor of flue gas is compensated by the decrease of energy consumed by the compressor of fresh air. Based on the Low heating value (LHV) of the natural gas, the flue gas recirculation increases the overall efficiency of the power plant by 1.1% from 57.5% from to 58.2%.
Determining the Efficiency of WWTP in Khoy Power Plant and Improving Phosphorus Removal by Anoxic-Oxic Process
M Aganeghad,A.R Mesdaginia,F Vaezi
Iranian Journal of Health and Environment , 2009,
Abstract: "n "nBackgrounds and Objectives: Now a days modified activated sludge ways are used for standard removing nutrient substances from waste water that is named Enhanced biological phosphorus removal One of the most suitable ways is Anoxic-Oxic(A/O) process. The goal of this research is investigation and solving existing problems of Khoy power plant(P.P) waste water treatment plant(WWTP)and optimizing of phosphorus removal in it."nMaterials and Methods: This research is done full scale in this treatment plant. The treatment plant was operating with extended aeration process, and some problems had, so in the first stage with in investigation of total efficiency, problems and their reasons determined. In the second stage after operational modifications existing problems was solved and real efficiency of treatment plant particularly for phosphorus(P) removal determined. In the third stage changes, system converted to A/O process and new system was tested with Changing parameters like food/microorganism(F/M), return sludge ratio(RAS)and sludge retention time(SRT)"nRisults: In the first stage the most important problems were over concentration of BOD,TSS, and P in effluent of treatment plant and overgrows of alga observed in parts of treatment plant and effluent receiving conduit. The main reason of high concentration of P was considered releasing of sludge. In the second stage operating condition modification efficiency of P removal increased from 50to 62 percent. In the end of third stage value of P removal reached to %82 and the most suitable of anoxic contact time was determined 3to4 hours, SRT terry day and F/M ratio o.12,that the most effective change has been the decrease of SRT to three days. "nConclusion: Adjusting of operating factors like SRT,RAS, sludge processing way in WWTP can increase P removal in them with in total efficiency remaining, such as in this case it was %12. In waste water treatment particularly for P removal the A/O process is suitable so in this project its effect on P removal efficiency has been %20.
The active commissioning process for a power reactor spent fuel reprocessing pilot plant in China
TianXiang Zhang,Jian Wang,Tao Wu,GuangJun Chen,YongQing Di Wu,FaQuan Ru
Chinese Science Bulletin , 2011, DOI: 10.1007/s11434-011-4600-2
Abstract: The process of a power reactor spent fuel reprocessing pilot plant (hereinafter referred to as the “pilot plant”) had been completed through active commissioning. Operational and technological parameters, such as shearing, dissolution, feed clarification, co-decontamination cycle, uranium and plutonium purification cycle, and the uranium and plutonium finishing facility, were identified. In addition, technical devices including extraction and mechanical equipment, electrical installation as well as instrumentation, and auxiliary systems for safety and adaptability were also verified. The commissioning results indicated that the recovery rate and decontamination coefficients of each system satisfied the designed index requirements and the qualified productions, i.e. uranium trioxide and plutonium dioxide, were produced. Monitored values at various monitoring points in the radiological protection system were within the control range and the discharge of waste water and waste gas complied with the relevant standards. This shows that independent and innovative technology for power reactor spent fuel reprocessing had been developed by our country.
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