Techno-Economic eva‎luation of Dividing-Wall Column Implementation in the Gas-to-Liquids (GTL) Process

10/22/2025 12:00:00 AM

The separation section in gas-to-liquids processes represents one of the most critical stages influencing the overall energy efficiency of the system. The feed considered in this study consists of 25 hydrocarbon components originating from LTFT Fischer–Tropsch synthesis, which were grouped into four major cuts LPG, naphtha, kerosene, an‎d diesel for modeling purposes. This feed corresponds to an industrial GTL unit with an approximate capacity of 41,760 barrels per day. The objective of this research is to analyze an‎d eva‎luate various configurations of dividing-wall columns with the aim of reducing capital an‎d operating costs, improving thermal efficiency, an‎d enhancing separation quality. Accordingly, six DWC configurations, based on two separation sequences (direct an‎d indirect) an‎d three wall positions (top, middle, an‎d bottom), were designed an‎d simulated using Aspen Plus. Optimization of key design variables—including the number of stages, feed location, reflux ratio, an‎d side-stream rates—was performed using a genetic algorithm an‎d based on minimizing the total annual cost while improving product purity. The resulting configurations were assessed through economic an‎d thermodynamic analyses, including exergy destruction an‎d steam consumption. The findings indicate that the Direct–Middle Wall arrangement provides superior economic an‎d thermal performance. This configuration achieved a total annual cost of approximately 7.99 million USD an‎d thermal exergy destruction of 16.04 GJ/h, representing nearly a 25% reduction relative to the base-case configuration. These improvements arise from more balanced energy distribution across the wall, reduced vapor–liquid mixing, an‎d a more favorable trade-off between energy use an‎d product purity. From an industrial perspective, employing the middle-wall configuration significantly reduces steam usage an‎d heat-exchanger duties, leading to considerable savings in the operating costs of GTL separation units. Overall, mid-wall dividing-wall columns present an effective strategy for enhancing energy efficiency, reducing costs, an‎d improving operational sustainability in GTL distillation systems.

تشديد فرايند , جداسازي فرايند تبديل گاز به مايع , برج ديواره‌تقسيم , چيدمان برج‌ها , شبيه‌سازي و بهينه‌سازي

Process intensification , Gas-to-Liquid’s process separation , Dividing Wall Column , column sequencing , Simulation an‎d optimization

Naghme Azizi

Norolah Kasiri - Amirhossein Khalili Garakani