Avoiding runaway scenarios in Fischer-Tropsch synthesis during startup: temperature and pressure influence

The operation of Fischer-Tropsch synthesis (FTS) pilot plants is essential to advancing Power-to-X strategies. However, conducting experimental campaigns with multiple startups introduces significant challenges due to the system's pronounced sensitivity to thermal instability and remains an unaddressed challenge in the literature. This experimental study analyzes the thermal response of a pilot-scale FTS reactor under controlled heating and pressurization, aiming to identify safe operating limits to prevent thermal runaway. In this experimental work, runaway was observed when the heating rate response (HRR) exceeded 15 ºC/h, while stable operation was achieved by limiting oil heating to <1 ºC/h. Pressurization from 10 to 20 bar at 3 bar/h induced a significantly lower thermal rate of 0.48 ºC/bar, offering an alternative to thermal ramping below 210 ºC. These findings highlight the importance of combining temperature and pressure ramping strategies to maintain thermal control during startup and underscore the need to evaluate the heating rate response continuously and maintain it below the critical threshold to ensure safe and stable operation.