How can this chemical plant be optimized?

A preliminary process flow diagram for a DME process is shown in Figure $3,$ in which $75,000$ metric tons per year of $99\mathrm{.}9$ mol$\%$ purity DME product is produced. Due to the simplicity of the process, an operating factor greater than $0\mathrm{.}98(8592$ h$/$y$)$ is used. Methanol, obtained from Unit $200,$ is combined with recycled reactant and vaporized prior to being sent to a fixed$-$bed reactor. The reactor is operated between $250\backslash$deg C and $400\backslash$deg C at a pressure of approximately $15$ bar. The single$-$pass conversion of methanol in the reactor is

expected to be between $40$ and $90\%.$ The reactor effluent is then cooled prior to being sent to the first of two distillation columns: T$-201$ and T$-202.$ DME product is take overhead from the first column. The second column separates the water from the unused methanol. The methanol is recycled back to the front end of the process, and the water is sent to wastewater treatment to remove trace amounts of organic compounds.