Evaluation of Process Structures and Reactor Technologies of an integrated Power-to-Liquid Plant at a Cement Factory

A novel carbon capture and utilization (CCU) process is described in which process-related carbon dioxide is captured from cement plant exhaust gas (10,000 tons/year) and converted with green hydrogen in a Fischer Tropsch synthesis to liquid, mainly paraffinic hydrocarbons (syncrude, approx. 3000 tons/year) which is finally processed to polyolefins. This CCU process chain is simulated with the software package ASPEN Plus V12.1®. In a first step, the influence of hydrogen production technology, such as PEM and SOEC, and reverse water-gas shift reactor (rWGS) technology (electrified and autothermal design) on plant specific efficiencies (Power-to-Liquid PtL, carbon conversion), product volumes, and investment, operating and net production costs (NPC) is investigated. Furthermore, process routes reducing the CO2 content in the Fischer Tropsch feed gas are elaborated, implementing a CO2 separation unit, or recycle streams back to the rWGS reactor. Unexpectedly, CO2 capture and recycle streams back to the rWGS show no significant impact on the performance of each process scenario, particularly in terms of the product quantity. However, lower PtL efficiencies and higher NPC are noticeable for these cases. The techno-economic assessment reveals that the use of a SOEC and an electrified rWGS reactor offers the technologically best and economically most optimized process chain with NPC of 8.40 EUR/kgsyncrude, a PtL efficiency of 54% and a carbon conversion of 85%.