A Nonlinear Dynamic Model of a Once-Through Subcritical Steam Generator

1976 ◽  
Vol 98 (3) ◽  
pp. 332-339 ◽  
Author(s):  
A. Ray ◽  
H. F. Bowman

A dynamic thermal-hydraulic model of a once-through subcritical steam generator is presented which allows the investigation of power plant system transients. The three-section (economizer, evaporator, and superheater) model with time-varying phase boundaries is described by a set of nonlinear differential and algebraic equations derived from the fundamental equations of conservation of mass, momentum, and energy. The transient response of 8 process variables, due to 5 percent independent step disturbances in 5 input variables at 100 percent load, is discussed.

2007 ◽  
Vol 13 (1) ◽  
pp. 27-32 ◽  
Author(s):  
Dragutin Debeljkovic ◽  
Mica Jovanovic ◽  
Nemanja Visnjic

A dynamic thermal-hydraulic mathematical model of the evaporator dynamics of a once - through sub critical steam generator was derived and presented. This model allows the investigation of evaporator dynamics including its transient responses. The evaporator was considered as part of a three-section (economizer, evaporator and super-heater) model with time varying phase boundaries and was described by a set of linearized discrete - difference equations which, with some other algebraic equations, constituted a closed system of equations possible for exact computer solution. This model was derived using the fundamental equations of mass, energy and momentum balance. For the first time, a discrete differential approach was applied in order to investigate such complex, two phase processes. Namely, this approach allows one to escape from the model of this process usually described by a set of partial differential equations and enables one, using this method, to simulate evaporator dynamics in an extraordinarily simple way. In the current literature this approach is sometimes called physical discretization.


Author(s):  
Ravin G. Naik ◽  
Chirayu M. Shah ◽  
Arvind S. Mohite

To produce the power with higher overall efficiency and reasonable cost is ultimate aim for the power industries in the power deficient scenario. Though combined cycle power plant is most efficient way to produce the power in today’s world, rapidly increasing fuel prices motivates to define a strategy for cost-effective optimization of this system. The heat recovery steam generator is one of the equipment which is custom made for combined cycle power plant. So, here the particular interest is to optimize the combined power cycle performance through optimum design of heat recovery steam generator. The case of combined cycle power plant re-powered from the existing Rankine cycle based power plant is considered to be simulated and optimized. Various possible configuration and arrangements for heat recovery steam generator has been examined to produce the steam for steam turbine. Arrangement of heat exchangers of heat recovery steam generator is optimized for bottoming cycle’s power through what-if analysis. Steady state model has been developed using heat and mass balance equations for various subsystems to simulate the performance of combined power cycles. To evaluate the performance of combined power cycles and its subsystems in the view of second law of thermodynamics, exergy analysis has been performed and exergetic efficiency has been determined. Exergy concepts provide the deep insight into the losses through subsystems and actual performance. If the sole objective of optimization of heat recovery steam generator is to increase the exergetic efficiency or minimizing the exergy losses then it leads to the very high cost of power which is not acceptable. The exergo-economic analysis has been carried to find the cost flow from each subsystem involved to the combined power cycles. Thus the second law of thermodynamics combined with economics represents a very powerful tool for the systematic study and optimization of combined power cycles. Optimization studies have been carried out to evaluate the values of decision parameters of heat recovery steam generator for optimum exergetic efficiency and product cost. Genetic algorithm has been utilized for multi-objective optimization of this complex and nonlinear system. Pareto fronts generated by this study represent the set of best solutions and thus providing a support to the decision-making.


2005 ◽  
Vol 235 (23) ◽  
pp. 2477-2484 ◽  
Author(s):  
Seong Sik Hwang ◽  
Hong Pyo Kim ◽  
Joung Soo Kim ◽  
Kenneth E. Kasza ◽  
Jangyul Park ◽  
...  

Author(s):  
Chen Chen ◽  
George M. Bollas

The increasing variability in power plant load, in response to a wildly uncertain electricity market and the need to to mitigate CO2 emissions, lead power plant operators to explore advanced options for efficiency optimization. Model-based, system-scale dynamic simulation and optimization are useful tools in this effort, and the subject of the work presented here. In prior work, a dynamic model validated against steady-state data from a 605 MW subcritical power plant was presented. This power plant model is used as a test-bed for dynamic simulations, in which the coal load is regulated to satisfy a varying power demand. Plant-level control regulates plant load to match an anticipated trajectory of the power demand. The efficiency of the power plant operating at varying load is optimized through a supervisory control architecture that performs set point optimization on the regulatory controllers. Dynamic optimization problems are formulated to search for optimal time-varying input trajectories that satisfy operability and safety constraints during the transition between plant states. An improvement in time-averaged efficiency of up to 1.8% points is shown feasible with corresponding savings in coal consumption of 184.8 tons/day and carbon footprint decrease of 0.035 kg/kWh.


2019 ◽  
pp. 119-126

Aplicación de la Teoría de Perturbación – Método Diferencial- al Análisis de Sensibilidad en Generadores de Vapor de Centrales Nucleares PWR-Caso Angra I Aplication of the Perturbation Theory- Differential Methodto Sensibility Análisis in PWR Nuclear Power Plant Steam Generator- Angra I Giol Sanders R, Andrade de Lima F, Marques A, Gallardo A, Bruna M, Zúñiga A Institución Peruano de Energía Nuclear Universidad Federal de Rio De Janeiro-Brasil DOI: https://doi.org/10.33017/RevECIPeru2011.0033/ RESUMEN En este trabajo basado en la tesis del Magíster Roberto Giol S. [1] presenta una aplicación del formalismo diferencial de la teoría de perturbación a un modelo termohidráulico homogéneo de simulación del comportamiento estacionario de uno de los generadores de vapor de la Central Nuclear tipo PWR Angra I del Brasil. Se desarrolla un programa de cálculo PERGEVAP tomando como base el código GEVAP de Souza[2]. El programa PERGEVAP permite realizar cálculos de sensibilidad de funcionales lineales (temperatura media del primario)y no lineales (flujo de calor medio a través de las paredes de los tubos del generador) con relación a las variaciones de ciertos parámetros termo-hidráulicos(flujo másico del primario, calor específico, etc), Los resultados obtenidos con este formalismo son luego comparados con los obtenidos del cálculo directo con el propio código GEVAP, pudiéndose verificar una excelente concordancia. Este método se muestra promisorio para efectuar cálculos repetitivos asociados al diseño y análisis de Seguridad de los componentes de las Centrales Nucleares. Descriptores: teoría de perturbación, método diferencial, sensibilidad, generador de vapor, central nuclear PWR. ABSTRACT This report presents an application of the differential approach of the perturbation theory to an homogeneous model of a PWR steam generator in the Angra 1 Nuclear Power Plan in Brazil under steady-state conditions. Program PERGEVAP was built fom the code GEVAP developed by Souza and allows sensitivity calculations of linear (average primary loop temperature) and non-linear (average heat flux) functionals due to variations in some thermo-hydraulics parameters (flow rate, specific heat, , etc). Results obtained with this approach are then compared with direct calculations performed using the GEVAP code, with excellent agreements. The method has good potential to treat repeated calculations needed in the design and safety analysis of the Nuclear Plant components. Keywords: perturbation theory, differential method, steam generator, PWR nuclear Power Plant.


Author(s):  
Paul S. Weitzel

Babcock & Wilcox Power Generation Group, Inc. (B&W) has received a competitively bid award from the United States (U.S.) Department of Energy to perform the preliminary front-end engineering design of an advanced ultra-supercritical (A-USC) steam superheater for a future A-USC component test program (ComTest) achieving 760C (1400F) steam temperature. The current award will provide the engineering data necessary for proceeding to detail engineering, manufacturing, construction and operation of a ComTest. The steam generator superheater would subsequently supply the steam to an A-USC intermediate pressure steam turbine. For this study the ComTest facility site is being considered at the Youngstown Thermal heating plant facility in Youngstown, Ohio. The ComTest program is important because it would place functioning A-USC components in operation and in coordinated boiler and turbine service. It is also important to introduce the power plant operation and maintenance personnel to the level of skills required and provide initial hands-on training experience. Preliminary fabrication, construction and commissioning plans are to be developed in the study. A follow-on project would eventually provide a means to exercise the complete supply chain events required to practice and refine the process for A-USC power plant design, supply, manufacture, construction, commissioning, operation and maintenance. Representative participants would then be able to transfer knowledge and recommendations to the industry. ComTest is conceived as firing natural gas in a separate standalone facility that will not jeopardize the host facility or suffer from conflicting requirements in the host plant’s mission that could sacrifice the nickel alloy components and not achieve the testing goals. ComTest will utilize smaller quantities of the expensive materials and reduce the risk in the first operational practice for A-USC technology in the U.S. Components at suitable scale in ComTest provide more assurance before applying them to a full size A-USC demonstration plant. The description of the pre-front-end engineering design study and current results will be presented.


Energy ◽  
2018 ◽  
Vol 155 ◽  
pp. 565-577 ◽  
Author(s):  
P.A. González-Gómez ◽  
J. Gómez-Hernández ◽  
J.V. Briongos ◽  
D. Santana

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