基于流程模拟软件Aspen Polymer Plus建立了己内酰胺水解聚合生产尼龙6的两段式工艺过程模型，利用该模型对某厂2万吨/年两段式生产工艺进行模拟，各聚合阶段内己内酰胺、环状二聚体含量、聚合物分子量，以及各聚合阶段温度分布和两聚合塔塔顶出水量等结果均与工业值吻合良好，模型可靠。在此基础上，进一步模拟考察了聚合反应过程中进料水含量、分子量调节剂含量、各聚合阶段温度和各聚合塔压力等因素对己内酰胺转化率、环状二聚体生成以及聚合产品分子量的影响，并进行了参数灵敏性分析。结果表明：较低的进料水含量、降低反应温度和前聚塔压力及提高后聚塔的真空度均有利于降低聚合产品中环状二聚体的含量；两个聚合塔下半段的温度变化对环状二聚体产生有显著影响，提高后聚塔真空度可显著提高聚合物分子量。以尼龙6连续聚合过程的环状二聚体含量调控为目标，在优化的操作条件下，尼龙6聚合物中环状二聚体的含量可降低约16%。%Abstrct:A model of two-steps Nylon-6 polymerization process was set up by Aspen Polymer Plus. As the simulational results fit all of the industrial operational data of 20 kt/a manufacture process well, including the composition of caprolactam and cyclic dimer, polymer molecular weight, temperature distribution, and the water yield from the top of two VK tubes, which indicated that the model was reliable. A sensitivity was analyzed by the model to evaluate the adjust ability of operational parameters, including the water and acetic acid contents in feed, temperature distribution and pressure of each VK tube in polymerization process. The results showed that low water content in feed, low reaction temperature, low pressure of the first tube and high vacuum of the secend tube contributed to less cyclic dimer fraction in polymer product. The temperature of the low-half section of two tubes strongly affect the cyclic dimer fraction. And the vacuum of the secend tube had a significant impact on the polymer molecular weight. Aiming to control the cyclic dimer fraction in the polymerization process, optimized operational conditions were obtained by Aspen Plus and the cyclic dimer fraction could decrease by about 16% correspondingly.
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