Abstract of Thesis presented at COPPE/UFRJ as a partial fulfillment of the requirements for the degree of Master of Science (M.Sc.)

Modeling and Control of Drum Level of a Steam Boiler of an Oil Refinery

Francisco de Assis Pinto Marques

April/2005

Advisors:

Liu Hsu Ramon Romankevicius Costa

Department:

Eletrical Engineering

      A nonlinear dynamic model for a drum-boiler with natural circulation is developed using real parameters of boilers that will be installed by Petrobras in the Isaac Sabbá Refinery (UN-REMAN), in Manaus-Am. The model construction follows a recently proposed method for obtaining dynamic models of low complexity appropriate for the control design of this kind of boilers. The resulting model was tested by simulation performed with the available plant data and appears to describe well the boiler dynamics, being able to reproduce the swell and shrink phenomenas, typical in this kind of boilers. The latter phenomena make the drum water level control more difficult. The developed model can be useful in the boiler control system design, as well as in its tuning. The tuning of several classical controllers was made through simulations using a PID control tuning Genetic Algorithm. The results have been compared with those obtained with classical tuning methods.