Boiler simplified model

The dynamic behavior of processes (pipe-vessel combinations, heat exchangers, transport pipelines, furnaces, boilers, pumps, compressors, turbines, and distillation columns) can be described using simplified models composed of process gains, dead times, and process dynamics. 

The three-step model, which is a new system theory, identifies the least common functions (unit operations) of a packed-bed combustion system. The three steps are referred to as the conversion system, the combustion system, and the boiler system. Previously, PBC has been modelled in two steps [3,15]. The novel approach with the three-step model is the splitting of the combustion chamber (furnace) into a combustion system and a conversion system. The simple three-step model is a steady-state approach together with some other simplifications applied to the general three-step model. The simple three-step model implies a simplified approach to the mathematical analysis of the extremely differentiated and complex PBC process. 

BESBETII - A computer code for the simulation of severe transients in LMFBR boilers, R.K. Thomasson. Numerical comparison between a reference and simplified two-phase flow models as applied to steam generator dynamics, J.-F. Dupont, G. Sarlos, D.M. Le Febve and... 

The steady state model is based on the mass and energy balances which were carried out over the furnace, heat exchanger area, economising section, dolezal, drum, generating section and superheaters. A set of nonlinear algebraic equations were used to accurately predict changes in the physical state of each system. Fig. 1 shows a simplified PFD for recovery boiler steam generation cycle. 

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