Study On Optimization Design Of Synthetic Ammonia System

Under circumstance of increasingly serious energy shortage,the small-scale synthetic ammonia devices with very high energy consumption in production are facing such difficulties as cancellation of the national protection policies,the increasing costs of raw materials,and the large investments on environmental treatment.As a result,only the plants owning advanced technology have the survival chance.At the same time,the devices with underdeveloped technology are doomed to be eliminated.Aiming at the underdeveloped technology and high energy consumption problems existing in the two sets of 100 kt/a high pressure synthetic ammonia devices in Shandong Hualu-Hengsheng Chemical Co.Ltd.,the chemical process simulation software ASPEN was used to simulate the synthetic ammonia devices,and deep analysis was carried out on the existing 200kt/a ammonia synthesis devices according to the calculation results to find out the bottleneck of high energy consumption,and then one ammonia synthesis device with the same scale was designed to substitute the two devices with high energy consumption,so as to achieve the purpose of reducing the energy consumption of the units.The results show that comparing with the existing 200kt/a ammonia synthesis process,the system resistance is reduced by 0.05MPa and the consumption of fresh gas is reduced by 299Nm3/h through optimizing the process of fresh gas filling and the recovery process of purge gas.Through cancelling the steam superheater,increasing the area of waste heat boiler,and adding the flow of the deaerator heater,the recovered amount of 2.5MPa steam is 3.3t/h more than that in the old device.After optimizing the process of the cooler,the refrigerating capacity of a 12,500 kcal ammonia compressor is saved,and the power consumption is reduced.The liquid disturbance problem formed by the vortex plate structure is solved by adding such equipment as the oil-water and ammonia separator,so that the gas inclusion phenomenon in emitted ammonia in ammonia separator is solved.Meanwhile,the separation effect of the separator and the performance of the ammonia synthesis catalyst are improved,and the sTable ility of the device is improved.The energy saving effect of the whole set is remarkable.