变负荷条件下的大型合成氨装置特性研究

Characteristics of Large-Scale Synthesis Ammonia Plant under Varying Load Conditions

为了探讨变负荷条件对合成氨过程的影响,结合某大型合成氨装置的流程和运行参数,利用ASPEN PLUS模拟整个合成氨过程,分析了在常用的部分负荷下整个合成氨装置的运行性能,获得了在部分负荷下加热炉、一段炉、辅锅等关键设备的热效率、火用效率以及反应器的反应转化率,提出了可以通过减少加热炉和一段炉的引风量和增加一段炉对流段蒸汽过热盘管面积来有效利用能量.采用Newton插值多项式的拟合方法,拟合出产量为1000～1500t/d的大型合成氨装置在常见85%～100%负荷范围内的吨氨能耗与负荷间的三次拟合曲线和公式,得出该合成氨装置的吨氨能耗模拟值为36.707～40.797GJ/t,和实测值吻合较好,误差小于3%.研究结果为实际的合成氨装置在变负荷下的生产运行与操作优化提供了参考依据.

To investigate the effect of varying load on the synthesis ammonia, the process of a large-scale ammonia synthesis plant is simulated with the process and operational parameters of the petrochemical company by ASPEN PLUS, and the operational characteristics on varying load conditions from 85% to 100% are analyzed. Thermal efficiency and exergy efficiency of the key equipment, such as heating-furnace, primary reformer and auxiliary boiler are evaluated, and reaction conversion ratio of the reactors is obtained. It is suggested that reducing the amount of input air to the heating-furnace and primary reformer and enlarging the area of the steam overheating coil in the convection part of the primary reformer can utilize energy efficiently. The curve and expression between energy consumption of the ammonia synthesis with load of 85 % to 100% are fitted by Newton interpolation polynomial for synthesis ammonia output in the plant from 1 000 t/d to 1 500 t/d. Thus it is predicted that energy consumption of the synthesis ammonia approaches 36. 707 GJ/t to 40. 797 GJ/t, which agree well with the field data with a deviation less than 3 %.