Research On Static And Dynamic Heat Transfer Character Of Power Plant Condenser

Condenser is one of the important auxiliary facilities of condensing steam turbine. Its performance affects the reliability and economical efficiency of the whole power plant. It is of great meaningful to study static and dynamic character of condenser deeply and to establish static and dynamic heat-transfer models for fault diagnosis and improving operation skill.Based on the analysis of condenser heat-transfer character, condenser static mathematic model and calculation procedure are established according to principle of heat-transfer balance. Take the condenser of 300MW unit as an example, the relationship of influencing factors and performance parameters is analyzed qualitatively and quantitatively. The influencing factors include cooling water inlet temperature, cooling water flux, steam load of turbine, fouling factor of cooling pipe. The performance parameters are condenser pressure, coefficient of heat transmission, and terminal temperature difference. Static character curve of condenser and variation range of influencing factors are also obtained. The calculation indicates that if the cooling water inlet temperature rises to 26℃ or the cooling water flux drops to 49% or condenser load rises to 160% or the thickness of fouling increases to 0.7mm, condenser vacuum begins to deteriorate.The working process of condenser is expressed by differential equation according to conservation of energy principle and principle of mass conservation. Dynamic mathematic model of condenser is established. Two main aspects are taken into consideration: turbulence model of circulation water flux and turbulence model of steam load. The turbulence model of circulation water flux is made up of three segments: dynamic response model of cooling water temperature to circulation water flux, dynamic response model of pipe wall temperature to cooling water temperature and steam average temperature to pipe wall temperature. The steam turbulence model needs to take two aspects into account. One is response of steam load to condenser pressure. The other is response of steam load to cooling water outlet temperature. The response of steam load to condenser pressure is integrating element. The response of steam load to cooling water outlet temperature includes two segments: dynamic response of pipe wall temperature to steam average temperature and dynamic response of cooling water outlet temperature to pipe wall temperature.Take the condenser of 300MW unit as an example, calculation indicates: when the circulation water flux increases, the dynamic response of condenser pressure to circulation water flux is differential element. When the circulation water flux decreases, the dynamic response of condenser pressure to circulation water flux is inertial element. When steam load varies, the dynamic response of condenser pressure is integrating element. When condenser pressure rises, the dynamic response of cooling water outlet temperature to condenser pressure is inertial element. When condenser pressure falls off, the dynamic response of cooling water outlet temperature to condenser pressure is differential element.The method put forward in this thesis presents a new way of studying condenser mathematic model and provides theoretical reference for deep research on it. Furthermore, it provides favorable support for application of heat-transfer character in condenser.