To determine the optimal refrigerating method for low temperature recovery (LTR) unit in propane dehydrogenation to propylene process, the simulations of LTR unit were performed by PRO/ II 8.2. The influences of temperature and pressure on separation effection were analysed, and the optimal separation temperature and pressure ranges were acquired. On the premise of the same separation effection, the utility consumptions and features of propylene + ethylene cascade refrigeration, propylene pre-cooled + Mixed Refrigerant Cycle ( MRC) refrigeration and propylene pre-cooled + hydrogen-expansion refrigeration were compared. The result shows that the discharge pressure of Charge Gas Compressor ( CGC ) is not the important factor for the separation effection of LTR unit, but the temperature has the significant influence on the separation result, and the economic separation temperature is from - 90 to -100 X,. Compared with the other two refrigerating methods, propylene + ethylene cascade refrigeration has more advantages such as high reliability, low energy consumption and easy operating, etc. , so this method is more suitable for propane dehydrogenation to propylene process.%为确立丙烷脱氢制丙烯工艺中低温分离单元的最佳制冷流程,采用PRO/Ⅱ8.2化工流程模拟软件,对低温分离单元进行模拟计算,考察了温度和压力对低温分离效果的影响,分析并确立了最佳分离温度和压力范围；在分离效果相同的前提下,分别比较了丙烯+乙烯级联制冷、丙烯预冷+混合制冷和丙烯预冷+富氢气膨胀制冷3种制冷流程的公用工程消耗以及各自的优缺点.结果表明:产品压缩机出口压力对分离效果影响较小,在确保下游装置能够正常操作的情况下,分离压力应尽可能低；分离温度是影响分离效果的主要因素,较为经济的分离温度为-90— - 100℃；相对于其他2种流程,丙烯+乙烯级联制冷流程具有技术成熟、能耗低和操作简单等优点,更适合于丙烷脱氢制丙烯工艺.
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