Study On The Simulation And Improvement Of Two-step Rectisol Process

Owing to the development of information technology, environment and life science technology and material science, a great progress has been obtained on the study of chemical engineering. It includes the micro-scale synthesis of atoms and molecules as well as the study on the global change. Although the chemical processes become more complex, the simulation systems are more convenient and effective, which is also low-cost than the experimentations. Therefore, it attracts world-wide attention and brings more applications with the advance of the simulation technology.The paper presents the applications of the rectisol process in gas purification of ammonia production using the coke oven gas. Also, an advance has been made on this chemical technology. The study is on the base of these problems from the actual condition of the rectisol process in gas purification of ammonia production with the coke oven. To understand the adaptability of the rectsiol pocess to actual condition of plants, a lot of simulation has been done with the available data.Then a new method or measure is set forth based on these simulation results. The equipment accounting is calculated by a simulation software with advanced and general function, which is called as Aspen Plus. The preliminary accounting can be gained by simulating the actual condition using Aspen Plus software. A new method is set forth according to analysis and optimization of the results.Carbon dioxide content is beyond the standard of the purified gas from absorption tower. To make the carbon dioxide content reach the standard, the actual production of the system is 70%, which is under the full capacity. The absorption system is accounted by the general simulation software Aspen Plus. An available optimization process is designed according to the simulation results. That is, a new circle on the bottom of the absorption tower can be added into Lurgi synthesis gas purification technology of rectisol process. This supplement can increase the saturation of carbon dioxide in the cycling methanol solvent, achieving a full production in the plant.The problem in pretreatment process, extraction process and azeotropic distillation system is that the benzene content in overhead production of pretreatment and the bottom production of azeotropic distillation fails to reach the standard, and the full capacity is not reached. Benzene is taken into the follow-up system by the connected stream. Benzene is cumulated in the system, which has important influence on the purity of the purified gas. A new method is brought forward according to the analysis of the simulation results. An ammonia cooler is added to the system. The temperature of the feedstock in the pretreatment process is decreased by this ammonia cooler. The purity of the purified gas meets the standard, and the amount of the methanol is lowered. Besides, the capacity of the disposal system is reduced.Thermodynamic model is adopted to simulate actual condition of the absorbing system consistent with the pretreatment process, extraction process and azeotropic distillation in the rectisol process. An improved system is set forth to make a full production of the plant. The process simulation can provide necessary information for the production technology which is useful to optimize the operation, thus achieving the goal of raising productivity, reducing energy consumption, stabilizing the production and finally gaining more economic benefit.