Evaluación de los sistemas de control de la Planta de Vapor del Laboratorio de Termofluidos.
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Date
2025
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Universidad de Concepción
Abstract
Se presenta el desarrollo de un modelo para predecir el comportamiento dinámico de la caldera de vapor del Laboratorio de Termofluidos de la Universidad de Concepción, con la finalidad de simular diferentes escenarios de control. El modelo de la caldera incluye: quemador de gas natural, cámara de combustión e intercambiador de calor de 3 pasos. Se desarrollan los balances de masa y energía en cada componente y se determinan los coeficientes globales de transferencia de calor para la cámara de combustión e intercambiador de calor a partir de datos experimentales. El modelo se implementa en el software EES y arroja como resultado la evolución temporal de las diferentes temperaturas en el circuito de humos y la temperatura del agua. La validación del modelo se realiza mediante comparación con datos de ensayos en laboratorio. Los resultados presentan un ajuste entre el modelo y la experimentación con error inferior a 5%. El modelo de control de combustión se obtiene linealizando la ecuación diferencial de temperatura de agua en el punto de operación, donde se consiguen las funciones de transferencia de la temperatura del agua en función de la temperatura de los gases y la demanda de vapor, luego las funciones de transferencia de la temperatura de los gases se obtienen por medio del modelo dinámico simulando escalones en el flujo de combustible y exceso de aire. El modelo de control de agua de alimentación se alcanza aplicando directamente transformada de Laplace en el balance de masa. Los sistemas de control modulante diseñados responden correctamente ante perturbaciones y logran mantener las variables controladas en el punto de operación. Finalmente se realiza una comparación entre el sistema de control diseñado y el actual, obteniéndose una mejora en la eficiencia de 4%.
The development of a model to predict the dynamic behavior of the steam boiler at the Thermofluids Laboratory of the University of Concepción is presented, with the aim of simulating different control scenarios. The boiler model includes a natural gas burner, combustion chamber, and a three-pass heat exchanger. Mass and energy balances are developed for each component, and the overall heat transfer coefficients for the combustion chamber and heat exchanger are determined from experimental data. The model is implemented in EES software and outputs the temporal evolution of the different temperatures in the flue gas circuit and the water temperature. The model is validated by comparing it with laboratory test data. The results show a fit between the model and the experiments with an error of less than 5%. The combustion control model is obtained by linearizing the differential equation for water temperature at the operating point, where the water temperature transfer functions are obtained as a function of gas temperature and steam demand. The gas temperature transfer functions are then obtained using the dynamic model, simulating steps in fuel flow and excess air. The feedwater control model is achieved by directly applying the Laplace transform to the mass balance. The designed modulating control systems respond adequately to disturbances and manage to maintain controlled variables at the operating point. Finally, a comparison is made between the designed control system and the current one, resulting in a 4% efficiency improvement.
The development of a model to predict the dynamic behavior of the steam boiler at the Thermofluids Laboratory of the University of Concepción is presented, with the aim of simulating different control scenarios. The boiler model includes a natural gas burner, combustion chamber, and a three-pass heat exchanger. Mass and energy balances are developed for each component, and the overall heat transfer coefficients for the combustion chamber and heat exchanger are determined from experimental data. The model is implemented in EES software and outputs the temporal evolution of the different temperatures in the flue gas circuit and the water temperature. The model is validated by comparing it with laboratory test data. The results show a fit between the model and the experiments with an error of less than 5%. The combustion control model is obtained by linearizing the differential equation for water temperature at the operating point, where the water temperature transfer functions are obtained as a function of gas temperature and steam demand. The gas temperature transfer functions are then obtained using the dynamic model, simulating steps in fuel flow and excess air. The feedwater control model is achieved by directly applying the Laplace transform to the mass balance. The designed modulating control systems respond adequately to disturbances and manage to maintain controlled variables at the operating point. Finally, a comparison is made between the designed control system and the current one, resulting in a 4% efficiency improvement.
Description
Tesis presentada para optar al título de Ingeniero/a Civil Mecánico/a.
Keywords
Sistemas de control, Combustión, Calderas de vapor