Simulation and investigation of thermodynamics and energy of methanol purification unit

Methanol is an important industrial chemical, and its synthesis and purification units are among the most widely used ones in the field of energy. The two-column separation unit of methanol has been evaluated from the thermodynamic and energy points of view in the present study. The simulation has been done by Aspen Hysys V11 and the SRK equation has been regarded as the most appropriate equation of state (EOS) for this simulation with the mean relative error (MRE) of 2 %. Then, the design of the heat exchanger network (HEN) has been developed using the Aspen Energy Analyzer V11. Both distillation towers have been evaluated using the pinch technology. As a result, the amounts of the used hot and cold utilities have been LP = 1.482 × 10^8, MP = 1.57 × 104, and Air = 1.423× 10^8. Besides, the total heating and cooling targets of the process have been 1.482 × 10^8 and 1.423 × 10^8 respectively. Then, the Δ𝑇𝑇𝑚𝑚𝑚𝑚𝑚𝑚 (minimum allowable temperature difference between hot and cold currents) and its effect on the annual cost have been investigated. The optimum value of Δ𝑇𝑇𝑚𝑚𝑚𝑚𝑚𝑚 is determined to have better-operating conditions and to meet the design of the HEN economically. Reducing Δ𝑇𝑇𝑚𝑚𝑖 𝑛 increases operating costs and reduces energy costs.