The Study On The Integration Process Of Rectisol Process And Withdrawal Of Methane Process By Deep Refrigeration

Using coal resource to substitute partial oil and gas resource is the only way for economic sustainable development of our country. The reserves of oil and natural gas is not abundant relatively, but the coal reserves is abundant, so it's important to develop the study of using coal to make oil, natural gas and chemical product. The consumption of methanol is inferior to the ethylene, the propylene and the benzene and ranks four. Methanol is not only important chemical raw material, but also it is pure fuel. To develop the study of using coal to make methanol is not only the need of our country's energy safety, but also it is the need of high speed of development of chemical industry. The crude gas of methane-synthesis is carbon monoxide and hydrogen, and they can be made by coal, natural gas, light hydrocarbon, pyrolysis gas and coke oven gas. Recently, with the lack of natural gas and petroleum resource day after day, taking use of coal to produce methanol is recognized in the place which has plenty of coal resource. During the technology process of producing methanol using the Lurgi furnace coal gas as raw material, the workshop section of coal gas purification is very important tache. The sulfide of coal gas can make a very bad effect during the process of methanol production, and it can make the catalyst poison, so it must be cleaned utterly.The methanol synthesis gas adopting the Lurgi furnace pressurized coal gasification technology contains certain amount of light hydrocarbon material, carbon dioxide, sulfur oxides, ammonia, benzene and other harmful impurities, and they must be cleared. The Rectisol process is a physical absorption method of using the excellent character of low temperature methanol to remove the light hydrocarbon, carbon dioxide, sulfureted hydrogen, carbon oxysulfide, cyanide and so on, and it can remove the sulfides from the synthesis gas by 0.1ppm. The characters of the Rectisol process are as follows: good absorbency, high gas purification degree, carbon dioxide can be removed from export gas by 10-20ppm, and the inorganic and carbon oxysulfide can be cleaned by less than 0.1 ppm; as a absorbent, the methanol can be acquired easily, and it is very cheap; its selectivity is good, and the solubility of carbon dioxide, sulfureted hydrogen and carbon oxysulfide is very big, but the solubility of hydrogen, carbon monoxide and methane is very small; the temperature of boiling point is low, and its hot regeneration temperature is low, and the enemy of consumption is also low. The purified methanol synthesis gas after Rectisol process also contains the inert gases, such as methane and so on, so it must be controlled below certain amount. The methane content of synthesis gas made by Lurgi furnace is very high, the inert gas methane can be withdrawn by deep refrigeration separation, and this process can save the equipments of methane translation and acquires a purified methane side product which can be used as the substitute or supply of LPG fuel and natural gas.Because the content of methane in the technology generation gas using the Lurgi fixed bed furnace is very high and current domestic natural gas's market foreground is very extensive, the process of adopting deep refrigeration to withdraw methane inlet gases from the raw material gas for methanol synthesis after the purification of Rectisol process has strongly actual meaning. Both the Rectisol process and deep refrigeration separation are operated at low temperature, so the effect of energy saving is pretty good when using them together. Adopting the process of the integration about Rectisol process and deep refrigeration separation, the sulfureted hydrogen and carbon dioxide gas was eliminated effectively and the inert gas methane of the phase of methanol-synthesis was withdrawn. This paper has designed a more economy process by the simulation and optimization analysis for the total flow using current simulation software.