Modeling and Simulation of a Process Plant for the Production of Formaldehyde from Methanol

Formaldehyde is used in the production of value-added chemicals such as melamine, urea-formaldehyde and phenolic resins. An important ingredient in the chemicals used to produce resins, adhesives, plywood and particleboard, insulation, and lubricants, formaldehyde is produced commercially by the catalytic oxygenation of methanol. In this research, a novel integrated plant is developed for the production of formaldehyde from methanol. The process plant consists of three sections: (1) evaporator, (2) reactor, and (3) absorber. Fresh methanol is mixed with water and oxygen from the air and enters a heat exchanger where it is vaporized. The combined mixture goes directly to the reactor where partial oxidation and dehydrogenation of methanol occurs. The mixture of unreacted reactants and products enter the absorption column where the unreacted mixture is removed from the top as off gas and recycled back, and a 37% solution of formaldehyde and water is recovered from the bottom. The steady-state behavior of the overall plant is simulated in the ASPENPlus environment and the predictive capabilities of this model is tested by comparing the results from the literature. 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. Then, a dynamic model is developed in ASPEN Dynamics and the effect of disturbances on plant performance is studied. The dynamic model is utilized to conduct a variety of “what-if” studies to determine conditions where the production of formaldehyde is optimized. Furthermore, opportunities for utilizing process control strategies to improve plant operation are studied. A comparative economic assessment based on existing plant information indicates that the use of process integration techniques has the potential to reduce costs significantly.