Optimizing the integrated design of boilers - simulation

Kim Sørensen, Claus M. S. Karstensen, Thomas Joseph Condra, Niels Houbak

Research output: Contribution to book/anthology/report/conference proceedingArticle in proceedingResearch

Abstract

Boilers can be considered as consisting of three main components: (i) the pressure part, (ii) the burner and (iii) the control system. To be able to develop the boilers of the future (i.e. the boilers with the lowest emissions, the highest efciency, the best dynamic performance etc.) it is important to see the 3 components as an integrated unit and optimize these as such. This means that the burner must be designed and optimized exactly to the pressure part where it is utilized, the control system must have a conguration optimal for the pressure part and burner where it is utilized etc. Traditionally boiler control systems have been designed in a rather simple manner consisting of a feed water controller and a pressure controller; two controllers which, in principle, operated without any interaction - for more details on boiler control see [4]. During the last year Aalborg Industries A/S has together with Aalborg University and The Technical University of Denmark carried out a project to develop the Model based Multivariable Control System . This is foreseen to be a control system utilizing the continuously increasing computational possibilities to take all the important operation parameters into account. The present study covers re-tube boilers. To be able to minimize the size (i.e. volume) of the boiler and, at the same time, obtain the best possible dynamic performance, it is important to minimize the water level uctuations in the boiler as much as possible. In the present study a detailed dynamic model of the boiler has been developed based on a number of sub models (Furnace, Convection Zone and Water and Steam), that are nally merged into the overall model. The models are developed as dynamic models consisting of both Ordinary Differential Equations and algebraic equations, together formulated as Differential-Algebraic-Equation (DAE) systems. For integration in SIMULINK the models have been index-reduced to Ordinary- Differential-Equation (ODE) systems. The simulations have been carried out by means of the MATLAB/SIMULINK integration routines. For verifying the models developed, detailed tests have been carried out on a full scale test plant. The tests on the plant have been carried out as step-inputs on, for example, steam ow and responses of furnace temperature, boiler outlet temperature and water level, have been measured. The part of the parameters in the dynamic model that are difcult to estimate/calculate have (on the basis of the tests) been determined by means of a least-square data tting, the minimums have been found by means of a Gauss-Newton algorithm and physically veried afterwards. The dynamic boiler model will be applied for developing controllers and adapting the parameters for the controller.
Original languageEnglish
Title of host publication17th International Conference on Efficiency, Costs, Optimization, Simulation and Environmental Impact of Energy Systems (ECOS 2004)
Volume3
Publisher<Forlag uden navn>
Publication date2004
Pages199-1411
ISBN (Print)9684890273
Publication statusPublished - 2004
Event17th International Conference on Efficiency, Costs, Optimization, Simulation and Environmental Impact of Energy Systems (ECOS 2004) - Guanajuato, Mexico
Duration: 7 Jul 20049 Jul 2004

Conference

Conference17th International Conference on Efficiency, Costs, Optimization, Simulation and Environmental Impact of Energy Systems (ECOS 2004)
Country/TerritoryMexico
CityGuanajuato
Period07/07/200409/07/2004

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