Dynamically Operated Fischer-Tropsch Synthesis in PtL-Part 1: System Response on Intermittent Feed

Abstract

Society is facing serious challenges to reduce CO2 emissions. Effective change requires the use of advanced chemical catalyst and reactor systems to utilize renewable feedstocks. One pathway to long-term energy storage is its transformation into high quality, low-emission and CO2-neutral fuels. Performance of technologies such as the Fischer-Tropsch reaction can be maximized using the inherent advantages of microstructured packed bed reactors. Advantages arise not only from high conversion and productivity, but from its capability to resolve the natural fluctuation of renewable sources. This work highlights and evaluates a system for dynamic feed gas and temperature changes in a pilot scale Fischer-Tropsch synthesis unit for up to 7 L of product per day. Dead times were determined for non-reactive and reactive mode at individual positions in the setup. Oscillating conditions were applied to investigate responses with regard to gaseous and liquid products. The system was stable at short cycle times of 8 min. Neither of the periodic changes showed negative effects on the process performance. Findings even suggest this technology’s capability for effective, small-to-medium-scale applications with periodically changing process parameters. The second part of this work focuses on the application of a real-time photovoltaics profile to the given system.

Dynamically Operated Fischer–Tropsch Synthesis in PtL—Part 2: Coping with Real PV Profiles

“…In microstructured fixed bed reactors, issues like hot-spot formation and associated deactivation do not apply ab initio, as shown in our previous work (Part 1) [38]. Hot spots are negligible and high per-pass conversion can be established without sintering effects.…”

“…The pilot scale setup for up to 7 L d −1 of liquid and solid product from previous publications was used for this work [18,38]. The microstructured fixed bed reactor using cobalt as active catalyst component was used as described elsewhere [16].…”

“…It is obvious that potential selectivity or conversion advantages from forced feed cycling or temperature swing or other types of unsteady-state operation must overcome additional cost and complexity brought into the system design [20,22,23]. In the context of PtL applications, the reduction of intermittent hydrogen storage is a clear reduction of capital costs enabled by dynamic operation [22][23][24]38]. Only a small number of publications investigated potential effects from dynamic operation on the FTS, mostly before the 1990s [20,37].…”

CO2‐neutrale Fischer‐Tropsch‐Kraftstoffe aus dezentralen modularen Anlagen: Status und Perspektiven

“…Änderungen in der Verweilzeit wurden von Änderungen im Synthesegasverhältnis begleitet. Über die Manipulation des Drucks im Kühlkreislauf des verdampfungsgekühlten Mikrofestbettreaktors lässt sich die Temperatur der Reaktion instantan steuern, sofern man sich im isothermen Nassdampfgebiet befindet . Hiermit lassen sich beispielsweise Umsatzeinbrüche durch den lastflexiblen Betrieb kompensieren, um die Produktionsmenge und ‐qualität steuern zu können.…”

Influence of Power‐to‐Fuel Plant Flexibility Towards Power and Plant Utilization and Intermediate Hydrogen Buffer Size

“…Thus, hydrogen and CO 2 need to be fed both dynamically. In Fischer-Tropsch synthesis, the catalyst deactivation is less important as can be found in some studies varying the H 2 /CO or H 2 /CO 2 feed ratio [13][14][15][16][17][18], but the reactor needs to be secured from complete hydrogen consumption, which on the other hand requires fast control over the reactor temperature [14,15]. However, all of these studies only considered the operation of the FT reactor or synthesis chain alone.…”