抽凝改背压机组汽水系统方案设计与对比分析

Comparison Analysis on Renovation Schemes of Steam-Water System in Transforming Extraction Condensing Unit into Back Pressure Unit

上海汽轮机厂60 MW等级单缸抽汽凝汽式机组需要改造为30 MW背压式发电机组。抽汽凝汽式机组的汽封系统为供汽和漏汽结合,而背压式机组只有漏汽汽封系统,二者完全不同。介绍了其中汽水系统的设计改造方案。在最大限度保留原有机组设备,包括其辅助系统的原则下,针对汽封和疏水系统进行了改造,尽可能使各接口的压力和管道走向等与原机组匹配。由于取消了机组抽汽,且后半缸在闷板之后光轴运行,因此疏水点和系统配置需要重新设计。提出了2个汽封系统的改造方案,即封堵部分漏汽腔室,保留外部2档漏汽接管的方案,以及利用原有漏汽管道对端部汽封接法进行合理优化,以匹配背压机组需求的方案,并进行了比较。以二者对机组的性能影响和配置便捷性为标准,确定后者为优选方案。研究成果可为类似的改造项目中汽水系统的设计提供参考。

The 60 MW extraction condensing unit with single cylinder made by Shanghai Turbine Plant needs to be transformed into 30 MW back pressure unit.The sealing systems of extraction condensing unit and back pressure unit are completely different.The former system consists of steam supply and leakage components,while the latter is only for steam leakage.The renovation schemes of steam-water system in this project were presented.Under the principle of retaining the original unit equipment to the maximum extent,with the auxiliary system included,the reform of the sealing and water drainage system was carried out,during which the pressure and pipeline direction of each joint were made to match the original unit as much as possible.Because the steam extraction was cancelled,and the rear half cylinder behind the blocker would operate with bare rotor,the water drainage point and system configuration should be redesigned.Two renovation schemes of sealing system were proposed,one was to plug part of the steam leakage chamber and retain the external two leakage pipelines,the other was to utilize the original steam leakage pipelines to optimize the seal leakage arrangement so as to meet the requirement of back pressure unit.Comparison was carried out between the two schemes with the standard of the impact on unit performance and the convenience of configuration,and it was determined that the latter was the optimal scheme.The research results can provide reference for the design of steam-water system in similar reform projects.