Mathematical model of the steam-water cycle for CHP unit with bleed-condensing turbine

The diagnostics of operation for the energy conversion systems is realized as a result of collecting, processing, evaluating and analyzing the measurement signals. Thus, determination of the process state, understood as the evaluation of the hereof process deviations from the reference standard process is possible. Researches focused on the identification of the process operation states changes have been developed in the diagnostics of the energy processes. The existing thermal diagnosis systems, which goal was energy evaluation of the operation, are enriched with the modules, which enable to localize the causes of excessive energy consumption. It requires application of the simulation models of the thermal processes. Additionally, simple models with short calculation time are necessary for the thermal diagnostics systems needs. Such models can be obtained with the utilization of the empirical modelling methods. Good results brings construction of the analytical model with the auxiliary empirical functions built-in. The paper presents mathematical model of the steam-water cycle for cogeneration heat and power (CHP) unit with bleed-condensing turbine containing mass and energy balances and auxiliary empirical equations describing the steam expansion line and the heat transfer processes in the heat exchangers. Worked out simulation model contains partial models of the turbine, the heat exchangers and condenser. Exemplary calculation results are presented.