考虑高温水泄漏影响的凝水泵启动过程仿真分析

针对某船用给水机组凝水泵在备用状态和备用转换启动过程中,由于高温除氧水进入凝水泵及其吸入管路而在机组启动后发生汽蚀,导致凝水泵出口压力长时间达不到规定要求的问题,在基于差异演化算法辨识得到凝水泵各级叶轮扬程-流量-转速模型、构建凝水系统管路与阀门模型、利用SimuWorks仿真平台建立整个凝水系统仿真模型并进行模型验证的基础上,通过仿真得到了在不同高温除氧水漏泄量的条件下,凝水泵内部各主要节点的凝水焓值、压力、温度或含汽率等参数随机组转换过程的变化情况. 研究结果表明,当凝水泵因吸入闸阀存在漏泄而导致水泵内部在启动前充满热水、来自正在启动的机组和已丧失正向流量的停用机组的高温水泄漏量较大时,正在启动的凝水泵就会发生汽蚀而不能及时建立出口压力. 论文运用热力学揭示了船用凝水系统一种特有故障的机理,对于系统的设计改进和故障排查具有重要参考价值.

Simulation analysis on startup period of condensate pump considering impact of high temperature water leaking

For the defects that the outlet pressure of condensate pump fails to meet the prescribed requirement during startup period of a marine feed water unit due to the fact that high temperature deoxidizing water enters the condensate pump and its suction pipeline during the standby state and the standby switching start-up, which leads to the cavitation of condensate pump, and on the basis of the head-volume flow rate-rotation speed model of each impeller obtained by Differential Evolution algorithm, the model of condensate system pipeline and valve, and the whole condensate system simulation model were established with SimuWorks simulation platform, and the changes of parameters such as enthalpy, pressure, temperature and the rate of vapor content with the switching process of the unit were obtained by simulation under the condition of different high temperature deoxidizing water leakage. The results show that the startup condensate pump will cavitate and its outlet pressure cannot be established in time when the condensate pump is filled with hot water before startup due to the leakage of suction gate valve, as well as the leakage of high temperature water from the startup unit and the outage unit which has lost drainage ability is large. Thermodynamics is used to reveal a special fault mechanism of marine condensate system, which has important reference value for system design improvement and fault detection.