Energy-saving And Comsuption-reducing Reconstruction Of Ammonia Synthesis System And Simulation Of Technology Process

Ammonia Synthesis is one of the chemical-based industries, which plays animportant role in national economy. Based on the reconstruction project ofSINOPEC Hubei Chemical Fertilizer Branch Co., the paper studies on thetechnology of energy saving. To save the energy, the inlet syngas flow incompressor circuit is reduced to decrease the amount of frozen of separationAmmonia. Additional molecular sieves are first studied then thereconstruction processes of Synthetic Ammonia are calculated by Aspen Plus.Aspen Plus can simulate the process of Synthetic Ammonia system. Byselecting the appropriate property methods, cell models, breaking streams andthe convergence approach, and then enter information of streams andoperating data of unit models; the software can run and simulate the processto gain the outcome. And compared with the data of plant, it is found thaterror is small, the software can be used for calculations of materials andenergy balance of ammonia systems. The results show that ammonia systemis modified and the production capacities are apparently increased, and alsoachieve the purpose of energy saving. Therefore, the reconstruction process isconducive to long-term development for enterprises.The paper mainly describes the reconstruction project of Hubei ChemicalFertilizer Branch Company that adopts the latest Shell Coal GasificationProcess. Based on Insitu S-200technology from Denmark TopsΦe company,equipments of ammonia plant are rebuilt for energy saving.The results of the research are as follows:（1） After installing the molecular sieve device, the total containing of oxidein synthesis gas is less than0.001%. After adsorbed by the molecular sieve,the containing of H-2O, CO₂and CO in the entering gas are decreasedsignificantly that improves the quality of the gas, thus increasing the activity of the catalyst and extending it’s life; With a molecular sieve the location of"cold" and "hot" in the loop is reasonable. It can save the amount of frozen ofpurge gas ammonia cooler125-C; When the new molecular sieve is operatednormally, the system pressure drop is smaller, thus minimizing the pressureloss between the high and low-pressure cylinder of gas compressor as a resultof adopting the molecular sieve synthesis to saving power consumption ofcompressors.（2） Because of the complexity of ammonia process, the software Aspenplus is used for simulating the technological process of Synthetic Ammonia.By selecting the property method of RK-SMHV2, R-plug module as thereactor, Wegsstein as the convergence method, the choice reflects the actualsituation of the ammonia production. First the outcomes are compared withdata of plant and it is found that error is small. Two kinds of results areconsistent comparatively. Then materials and energy balance of ammoniasystems are simulates and calculated.The results are as follows:①After reconstructed, the heat load of the heat transfer device is reducedon7.78%; the cooling capacity of refrigeration system is increased on26.52%.And the condensation of exports ammonia is also improved by0.8%.The ammonia production capacity rose with11%. So ammoniaproduction capacity is increased and energy consumption of equipment isreduced;②As the fresh air and circulation air are directly put into the reactor notinto the ammonia cooling, it reduces ammonia and water coolingconsumption.（3） After adopting the reconstruction project for Energy-saving of SyntheticAmmonia and molecular sieve, in June2006it runs successful. During thepast one year, the basic indicators meet the design requirements.