Pressure Dynamics of One Oil-Fired Drum Type Natural Circulation Steam Generating Unit

A mathematical model for a water level and pressure dynamics in the drum–riser–downcomer loop of natural circulation drum–type boiler is presented. The 11 [MW] oil-fired steam generation unit with natural circulation is considered. The model is based on the basis of fundamental conservation laws of mass, momentum and energy, together with very well known constitutive equations. The dynamic behaviour of each section is described in the mathematical terms and in the form of lumped parameter systems equations. The equations are linearized and manipulated into the state space form suitable for PC computer. Simulation results are shown compared with those in the literature in which an empirical model for two phase dynamics are employed. The presented model shows a reasonable prediction of water level and pressure dynamics for sudden changes in steam demand and other disturbances.