MVR系统非稳态热力学模拟

Unsteady thermodynamic simulation of MVR system

关键词:  机械蒸汽再压缩  非稳态  热力学模型  页岩气压裂返排液  模拟 

Key words:  mechanical vapor recompression  unsteady state  thermodynamic model  shale gas fracturing flow-back fluid  simulation

摘要:

建立了机械蒸汽再压缩系统的热力学模型,并对换热器无相变瞬态传热分析的模型进行了简化。在此基础上,以加热后的料液显热作为启动热源,以稳态计算数据为基础,利用迭代法对系统非稳态运行过程进行了模拟。结果 表明:在闪蒸阶段,系统内蒸汽流量增长较快,当换热量达到蒸发器换热的最大值时,蒸汽流量出现明显拐点,并呈下降趋势直至稳态；系统约在2 500 s后达到稳态运行。压缩机最大功率及最大进气量均出现在非稳态运行过程中,与稳态值相比,分别高出41.89%和32.56%。 

Abstract:

In this study, a thermodynamic model of a mechanical vapor recompression system was established, and the no phase change transient heat transfer model of heat exchanger was simplified. Further unsteady running progress using sensible heat of heated feed liquid as starting heat source was simulated by using iterative method based on steady state calculation data. The results showed that the vapor flow rate would grow rapidly at the beginning, forming an apparent inflection point when the heat exchange reaches the maximum state. Thereafter the flow rate would gradually decrease to the steady state after slowly increasing to the maximum value. Eventually, this progress would last for about 2 500 seconds. Both the maximal compressor power and the maximal compressor intake flowrate would achieve during the unsteady running progress, which are 41.89% and 32.56% higher than the steady state value, respectively.