600 MW直接空冷凝汽器变工况模型建立及特性分析

Model establishment and characteristic analysis of 600 MW direct air-cooled condenser in variable conditions

为解决因直接空冷凝汽器变工况特性计算不准确,影响直接空冷机组冷端系统运行优化效果的问题,基于厂家原始数据资料,采用ε-NTU法,考虑凝汽器冷凝温度变化引起的实际凝结热的变化及变工况下排汽压损的变化,建立了某600 MW直接空冷机组凝汽器变工况特性计算模型。该模型计算结果与厂家提供的特性曲线对比,其最大误差为1.68%,满足工程精度要求,与传统模型相比,该模型计算精度更高。在所建立的空冷凝汽器变工况计算模型基础上,详细分析了环境温度、汽轮机排汽流量和迎面风速对凝汽器压力的影响。结果表明:凝汽器工作压力分别随环境温度、排汽流量的增大而增大,随迎面风速的增大而逐渐减小。环境温度越高,空冷凝汽器压力对环境温度、排汽流量及迎面风速的变化越敏感。

In order to solve the problem of inaccurate calculation of the variable conditions characteristics of the direct air-cooled condenser,which affects the optimization effect of the cold-end system of the direct air-cooled unit.Based on the manufacturer's original data,using theε-NTU method,considering the change in actual condensation heat caused by the change in condenser condensing temperature and the change in exhaust pressure loss under variable conditions,a calculation model for the off-design characteristics of a 600 MW direct air-cooled unit condenser was established.The calculation result of this model was compared with the characteristic curve provided by the manufacturer.The maximum error was 1.68%,which meet the engineering accuracy requirements.Compared with the traditional model,the calculation accuracy of this model was higher.On the basis of the established air-cooled condenser variable conditions calculation model,the influence of ambient temperature,steam turbine exhaust flow and face velocity of the air on condenser pressure was analyzed in detail.The results indicated that the working pressure of the condenser increased with the increasing of ambient temperature and exhaust steam flow,and gradually decreased with the increasing of the face velocity.The higher the ambient temperature,the more sensitive the air condenser pressure was to change in ambient temperature,exhaust steam flow,and face velocity of the air.