Process Systems Engineering of High-low Temperature Fischer-Tropsch Synthesis Integration in Olefin Production
Abstract A novel system combing high- and low-temperature Fischer-Tropsch synthesis (HTFT and LTFT) in olefin production is proposed. Utilizing syngas from coal gasification as the feed gas, the combined system integrates the advantages of HTFT and LTFT and results in an increased range of products, namely α-olefins (mainly C4, C6, and C8), synthetic lubricant, gasoline, diesel, naphtha, greatly enhancing the system’s market adaptability. The system avoids the risk of product market fluctuation, and especially realizes the objective of diversifying production and maximizing economic benefit. Ethylene oligomerization process is innovatively proposed to increase the α-olefins production. A techno-economic analysis was performed on the above system using Aspen Plus software. Results indicated that the income of α-olefins accounts for at least 20% of the total income of the system and this percentage increases with increasing contribution share of HTFT to the combined synthesis system. From the viewpoint of economic perspective, the optimal ratio of HTFT to LTFT for the HTFT - LTFT combined system with ethylene oligomerization scheme is 3:2. The project is expected to have a net present value of 11.45 billion USD, and internal rate of return of 28.31% under the current economic consumption, which shows excellent economic profits and demonstrates that the combined system presents the remarkable ability to resist market risks compared to traditional stand-alone HTFT or LTFT process under a low oil price scenario.