The key unit of kraft pulp production – the recovery boiler – ensures the regeneration of black liquor chemicals. The task of increasing the liquor reduction degree without changing the process technology or equipment design, i.e., through information and algorithmic means – automatic control is relevant. A higher guaranteed quality of recovery is provided by control algorithms synthesized on the basis of adequate mathematical models. The aim of this paper is a system analysis of the recovery boiler as a control plant and the development of an enhanced mathematical model suitable for synthesizing high-quality automatic stabilization systems. The methodology is based on the principle of sequential uncertainty removal for complex control system models (A.A. Vavilov). Unlike known approaches, the dynamics of the recovery boiler in the vicinity of a selected operating point are described as a multi-level LTI-class model. Combining analytical methods with experimental data processing for a specific operating mode made it possible to obtain mathematical models of an actual recovery boiler with parameters determined down to specific numerical values. The developed multilevel linear stationary model of the recovery boiler makes it possible to analyze the dynamics of subsystems and the unit as a whole, the stability of modes and the influence of disturbances, and justify the need to automatically maintain the required quality of technological processes in the vicinity of the selected mode. Symbolic models are applicable to most similar kraft process units. Parameters of fully defined models should be adjusted based on the results of processing data related to a specific unit and mode. The direction of further research is associated with the development of methods for analyzing the dynamics of complex control systems according to models of a hierarchical structure, as well as the synthesis of systems for stabilizing the regime and reducing the influence of perturbations.ls, as well as the synthesis of systems for regime stabilization and mitigation of the influence of disturbances
