Mathematical Model of a Steam Turbine Condenser

The main purpose of the condenser of a steam turbine unit is to condense the exhaust steam of the turbine and maintain the steam pressure behind the last stage under nominal conditions not higher than the calculated, which are determined on the basis of technical and economic indicators. Faults in the condensers lead to disruptions in the operation of the steam turbine, to its failures and breakdowns, loss of heat, water, and steam at the station, etc. In order to ensure the reliable operation of the condenser and improve the efficiency of its equipment, a mathematical model of the T-110/12.8 turbine condenser was developed, verified, and tested in relation to the conditions at the Almaty Power Plant (ALES) of CHPP-2. It is shown that the model can be used to build new standard characteristics of the condenser at steam flow rates in the condenser above the nominal values and supply of circulating water to the main bundles and raw water to the built-in bundles. The model takes into account the peculiarities of determining the steam pressure in various zones of the condenser when cooling water is supplied to the main and built-in bundles of tubes. With the help of the developed module of the monitoring system for the technical condition of the condensing unit of the T‑110/12.8 AlES CHPP-2 steam turbine, it was found that the deviation of the actual condenser performance (including steam pressure) from the standard (calculated) values occurs mainly due to contamination of the condenser tubes. The influence of air suction in most modes is insignificant. The mathematical model allows one to change the input parameters, build dependency graphs, conduct a computational experiment, and calculate performance indicators. A feature of the mathematical model of the condenser is that it is built according to a technique that takes into account the peculiarities of determining the steam pressure in various zones of the condenser when cooling water is supplied to the main and built-in bundles. Based on the results of an industrial experiment, a comparison was made of the values of standard, calculated, and actual condenser pressures for each mode.