| Deaerator plays a very important role in nuclear power system.In order to prevent noncondensable gases such as dissolved oxygen in water from corroding pipelines and related equipment,deaerator is set up in the secondary loop of nuclear power plant to remove dissolved oxygen in water.Therefore,it is necessary to pay attention to the change of thermal parameters of deaerator.The heat transfer process of steam and condensate water inside deaerator is different with different structures.The simple black box modeling method can’t reflect the difference of internal structure and heat transfer process of deaerator,and the accuracy of calculation results is low.This thesis carried out related research on the establishment of the simulation model of deaerator.The main work is as follows:(1)On the basis of studying the existing modeling methods of deaerator,the mathematical simulation models of rotary film deaerator,built-in deaerator and double-head deaerator which can reflect the internal structure and heat transfer process of deaerator are established.The model is divided into regions according to the different heat transfer modes in each deaerator.The heat transfer area is calculated according to the contact form between water and steam inside the deaerator.Through the empirical formula of heat transfer coefficient of direct contact between steam and liquid film or liquid drop and the modified formula of influence of noncondensable gas on heat transfer coefficient,the relevant heat transfer calculation is carried out.Based on the empirical formula for calculating dissolved oxygen in water and the oxygen mass balance relationship in deaerator,a model for calculating dissolved oxygen in feed water was established.(2)The deaerator simulation program is written according to the established deaerator simulation model,and the actual deaerator structure data and operation parameters are substituted into the written deaerator program,and the steady-state calculation results of the deaerator model under rated working conditions are obtained;The dynamic verification of deaerator program is carried out by means of reducing heating steam flow,water inflow flow and water outflow flow,and theoretical analysis is made on the results.In this thesis,the steady-state and dynamic simulation results of the relevant deaerator are obtained.By comparing the steady-state calculation results with the actual deaerator operation data,it can be concluded that the deaerator simulation program established in this thesis has a high accuracy.Through the analysis of the dynamic results,it is considered that the dynamic trend is consistent with the theoretical analysis,which can prove that the simulation model established in this thesis can reflect the actual heat transfer process of the deaerator well. |
