Simulation and Dynamic Analysis of an Integrated Plant for the Production of Methanol from Natural Gas

Methanol is an essential chemical for obtaining more complex chemical structures, such as acetic acid, methyl tertiary butyl ether, dimethyl ether, and methylamine. It is used in the manufacture of a variety of industrial and consumer products. In this research, a novel integrated plant for the production of methanol from natural gas is simulated and analyzed. The methanol manufacturing process is divided into three parts: (1) pre-treatment of natural gas, (2) conversion of natural gas to syn gas and (3) conversion of syngas to methanol. The pre-treatment step consists of compression and hydrodesulfurization stages. This is followed by steam reforming and secondary reforming to produce syn gas. The reformed gas is cooled and the excess heat is used for generating steam. The cooled syn gas is sent to a methanol synthesis reactor. Finally, a distillation train is used to purify methanol. The overall plant is simulated in the ASPENPlus environment and the predictive capabilities of this steady-state model is tested by comparing with plant data from a methanol synthesis plant in Beaumont, Texas. Then, a variety of process conditions are tested at steady state to optimize the production of methanol. Heat-integration tools are utilized for energy-saving and capital cost reduction opportunities. A comparative economic assessment based on existing plant information indicates that the use of process integration techniques has the potential to reduce costs significantly. Then, a dynamic model is developed in ASPEN Dynamics for the integrated plant and the effect of disturbances to the plant are tested. The dynamic model is utilized to conduct a variety of “what-if” studies to determine conditions where the production of methanol is optimized. Furthermore, opportunities for utilizing process control strategies to improve plant operation are studied.