多参数扰动下机械蒸汽再压缩系统动态特性及运行参数耦合规律研究

Material concentration and waste water treatment in petrochemical, pharmaceutical and other industrial field usually consume lots of energy, and using mechanical vapor recompression system to replace the multiple-effect evaporation is a development trend.. It is also a focus point for the near-zero emission of salty waste water. Parameters fluctuations of feed solution and operating condition usually cause the deviation between actual operating conditions and design ones, instability, inefficient compressor and even impeller failure of compressor. Therefore, the stablity and reliablity of this system can be improved by matching components reasonably and optimizing operating conditions. This project focuses on the dynamic performance and couple principle of parameters influenced by multi-parameters. A mathematical model coupled compressor, evaporator-condenser, pump is built to analyze the dyanmic performance of this system influenced by the feed solution and operating condition, such as mass flow rate, temperature, boiling point elevation, evaporating pressure, steam temperature, liquid level and so on. The couple principle of device parameters is also researched, such as suction pressure of compressor, temperature difference of heat exchanger and mass flow rate of pump. The correlation for the internal parameters of this complex thermodynamic system is revealed, and the stable operating boundary conditions and efficient regulation method are also explored. An experiment system is built to test the actual performance in order to guide the design and regulation of this system. The results are helpful for the optimal design of this system.

石化、制药等行业中物料浓缩、废水处理等过程耗能巨大，采用机械蒸汽再压缩系统替代多效蒸发是发展趋势，也是含盐废水“近零排放”的技术热点。料液参数波动、运行参数扰动是系统偏离设计工况、失稳、压缩机长期低效运行、甚至零部件失效的重要原因，合理匹配设备参数、优化运行调控策略是系统稳定、可靠运行的关键。本项目着重研究多参数扰动下系统的动态特性及运行参数间的耦合规律，通过建立耦合压缩机、蒸发-冷凝器、循环泵等组件的系统数学模型，分析流量、温度、浓度等料液参数及蒸发压力、蒸汽温度、液位等运行参数变化对系统运行特性的影响，研究压缩机吸气压力、换热器温差、循环泵流量等设备运行参数间的耦合规律，揭示多参数扰动下复杂热力系统内部参数关联机理，探索系统稳定运行边界条件及高效调控方法。实验研究小型机械蒸汽再压缩系统变工况运行特性，探索系统多参数关联设计方法及高效调控技术，为系统优化设计奠定基础。

机械蒸汽再压缩系统在物料浓缩、废水处理等过程具有明显节能优势，是石化、制药等行业含盐废水“近零排放”的技术热点。料液参数波动、运行参数扰动常使系统偏离设计工况，造成系统低效运行，研究运行参数耦合规律是合理匹配设备参数、优化运行调控策略的基础。本项目以机械蒸汽再压缩系统为研究对象，建立了描述核心设备和系统运行特性的数学模型，分析了喷水量、转速、吸排气压力等对水蒸气压缩机性能的影响，原料液参数、冷凝侧蒸汽参数沿换热管长度方向的变化，及物料进口参数、浓缩要求、运行参数等对处理能力（流量）、运行工况、系统功耗等参数的影响，探索了系统主要运行参数间的耦合关系。建立了基于煤化工废水的小型机械蒸汽再压缩实验系统，研究了水蒸气压缩机压比与流量、轴功率与饱和温差间的关系，测量了连续运行条件下系统处理量，分析了系统功耗及压缩机、真空泵、水泵等设备功耗分配，检测了处理前后典型水质参数变化。结果表明系统冷凝水流量可在0.77 t/h-1.15 t/h范围变化，蒸发器内饱和温差升高1℃时压缩机轴功率增大3.1kW-4kW，压缩机功耗约占系统总功耗的75.9%，浓缩液最大TDS为78650 mg/L，而冷凝水最大TDS仅为118mg/L，表明该系统适用于煤化工废水的浓缩过程。本项目建立的数学模型，能够较准确的预测多参数扰动下的系统运行特性，理论与实验研究结果可为系统优化设计及运行调控提供支撑。项目成果共发表学术论文3篇，其中SCI收录2篇，EI收录1篇，申请发明专利1项。