Mathematical Models of the Energy Characteristics of a Backpressure Steam Turbine Based on a Simulation Study

Technical University of Sofia, Department of Thermal Power Engineering and Nuclear Power Engineering, 1000, 8 Kl. Ohridski Blvd, Sofia, Bulgaria

^* corresponding author: kokhris@gmail.com

Abstract

The backpressure steam turbine installations for combined production generate thermal energy and electricity. The produced electricity depends on the heat load determined by consumers. Heat energy is released in the district heating system through water, which is heated with the exhausted steam in boiler-condenser (district heater). The operation regime of the installation is influenced by load of the released district heat and the temperature of the district heat water at the input and output of the boiler-condenser. The variables are heat load of the district heating system and temperature of district heat water at power plant output. The temperature of the district heat water at the boiler-condenser input is an uncontrollable variable, whose value depends on heat consumption. It influences the steam pressure in the boiler-condenser and the available enthalpy drop of the cogeneration installation. In this report, a verified simulation model is applied on a backpressure steam turbine installation, type SST-300 CE2L/V36S. A multivariate simulation is carried out, studying the performance of the installation in off-design regimes. The results obtained are used for the creation of regression models of the installation’s energy characteristics. They reveal the dependence between the energy characteristics of the cogeneration steam turbine by the released heat load in the district heating system and the temperature of incoming and outgoing district heat water. The accuracy of the developed models is evaluated through multiple correlation coefficients. The mathematical models could be successfully used to optimize the operating regime of the backpressure steam turbine installation.