Separation Efficiency Optimisation of Toluene–Benzene Fraction using Binary Distillation Column

Abstract

This work has been carried out to simulate a binary distillation column to separate Benzene and Toluene from BT fraction using Aspen Plus software. Benzene–Toluene separator is a normal two-phase distillation for pure aromatics. In Steel Plant, crude benzol recovered from the coke gas is fed to the Benzol Plant where benzolised oil undergoes benzol distillation, hydro-refining and extractive distillation and aromatic stripping column to produce pure BT fraction which is further pumped to BT Separation column in order to produce pure Benzene as top product and pure toluene as bottom product. This benzene is used mainly as an intermediate to make other chemicals and used in manufacture of drugs, dye, rubber, detergents, plastic and polymers. Thus, an attempt has been made to increase the production of high-purity Benzene and Toluene at optimum condition using Aspen Plus. In this paper, the feed flow rate, reflux rate and column stages are optimized using Aspen Plus as well validated by using Mc-Thile and Ponchon Savarit Method, while keeping the feed temperature and pressure constant. The purity of Benzene and Toluene is achieved as 99.99% and 99.70%, respectively, at different conditions such as feed flow rate 3165 kg/h, reflux rate 1.2 kg/h, temperature 80 °C and pressure 0.7 kg/cm². This high purity of solvents is achieved at 60th stage, whereas current running plant achieved the same purity at 65th stage. As compared to current running condition of the plant, the production rate of benzene is achieved 43%more than the existing plant data. At these optimized condition high purity and high production are achieved at expense of less energy consumption. It is validated by running the process in the industry at same conditions using the distillation column. The data almost matched with the simulated data.