The Design and Optimization of Extractive Distillation for Separating the Acetone/n-Heptane Binary Azeotrope Mixture.

Acetone and n-heptane are common solvents in the pharmaceutical industry and they have been found in wastewater. Under atmospheric conditions, the mixture of these compounds creates a minimum-boiling azeotrope. The extractive distillation process with a high boiling solvent is commonly utilized to separate the azeotropes in the industry to minimize waste, reuse resources, achieve clean production, and preserve the environment. In this work, extractive distillation was applied to separate the binary azeotropic system of acetone and n-heptane in wastewater using butyl propionate as a solvent. The characteristics of the process are designed and simulated via Aspen Plus. The simulation results showed that to get a distillate containing at least 99.5 mass% acetone, a solvent-to-feed ratio of 1.4, a reflux ratio of 1.5, a number of stages of 30, a feed stage of 26, a solvent stage of 10, and a solvent temperature of 298.15 K were required. The optimum operating parameters of the process were also obtained using the NLP optimization method, with the minimum total annual cost as the objective function. While the process was operating in optimal mode, CO2 emissions were calculated to be 0.0780 kg CO2/kg feed.

Efficient Production of Light Olefin Based on Methanol Dehydration: Simulation and Design Improvement.

BACKGROUND: Ethylene, propylene, and butylene as light olefins are the most important intermediates in the petrochemical industry worldwide. Methanol to olefins (MTO) process is a new technology based on catalytic cracking to produce ethylene and propylene from methanol. AIMS AND OBJECTIVE: This study aims to simulate the process of producing ethylene from methanol by using Aspen HYSYS software from the initial design to the improved design. METHODS: Ethylene is produced in a two-step reaction. In an equilibrium reactor, the methanol is converted to dimethyl ether by an equilibrium reaction. The conversion of the produced dimethyl ether to ethylene is done in a conversion reactor. Changes have been made to improve the conditions and get closer to the actual process design carried out in the industry. The plug flow reactor has been replaced by the equilibrium reactor, and the distillation column was employed to separate the dimethyl ether produced from the reactor. RESULT: The effect of the various parameters on the ethylene production was investigated. Eventually, ethylene is produced with a purity of 95.5 % in the improved design, and thermal integration was performed to minimize energy consumption. CONCLUSION: It was finally found according to the exothermic reaction of the dimethyl ether production, thermal integration in the process reduces the energy consumption in the heater and cooler.