Abstract:

To explore the feasible method of using the air compression heat in the large-scale air separation unit, it was proposed to use the compression heat to drive the organic Rankine - vapor compression refrigeration coupling cycle. The cooling capacity was used to cool down compressors inlet air, to achieve the purpose of self-utilization of compression heat and self-enhancing of compression process. Taking the compression process in a 60000 m³/h scale air separation unit as an example, MATLAB was used to model the compression heat self-utilization system. Further, with the goal of maximizing the system economy, firefly algorithm was used for the optimization of heat exchange area of the main evaporators in typical humidity area. The result shows that when the relative humidity of the inlet air is 70% and 30%, the energy saving rate of the multi-stage air compression heat self-utilization system can reach 4.4% and 4.6%, respectively, and the payback time is 4.4 a and 5.5 a, respectively. The system shows better energy-saving effect and higher economic value.

Key words: air compressor, waste heat recovery, organic Rankine cycle, vapor compression refrigeration, economics, thermodynamics process, firefly algorithm

摘要：

为探究大规模空分系统中空压机余热利用的可行方法，提出利用压缩余热驱动有机朗肯-蒸汽压缩制冷耦合循环，所得制冷量用于空压机入口空气冷却，从而提高压缩系统效率，实现空压机余热自利用和压缩过程自增效的目的。以6万空分规模中空压系统的余热回收为例，利用MATLAB对该余热自利用系统进行了热力学建模；进一步，以系统经济性最大化为目标，针对典型湿度地区的运行工况采用萤火虫算法对主要蒸发器换热面积进行优化。结果表明，在入口空气相对湿度为70%和30%时，该多级空压余热自利用系统的节能率分别可达到4.6%和4.2%，回收周期分别为4.4年和5.5年，系统显示出较好的节能效果和较高的经济价值。

关键词: 空气压缩机, 余热回收, 有机朗肯循环, 蒸汽压缩制冷, 经济, 热力学过程, 萤火虫算法