INTEGRATION OF BIOMASS GASIFICATION-BASED OLEFINS PRODUCTION IN A STEAM CRACKER PLANT ― CONSEQUENCES FOR STEAM BALANCES

摘要

This study investigates integration opportunities for biomass-based olefin production at a fossil-basedrnsteam cracker plant at the core of a chemical cluster. The work was conducted in the form of a case study consideringrnthe possible future partial replacement of approx. 200 kt/y of cracker olefin production capacity (approx. 25 % ofrntotal capacity) with biomass-based olefins produced via gasification, methanol synthesis and the methanol-to-olefinsrn(MTO) process. The partial switch of feedstock impacts the cluster site material and energy balances which in turnrncould have a significant impact on the overall carbon footprint benefits of the switch. A detailed analysis of steamrnbalance changes is thus an important step in the sustainability analysis of feedstock switching. This paper discussesrnimplications for site steam balance characteristics for (i) Base case operation with fossil-only feedstock and (ii)rnpartial substitution of the cracker units with MTO units fed with methanol. The MTO section was assumed to bernlocated at the cracker site, making use of existing olefin separation equipment. The results indicate that the partialrnfeedstock switch increases the cracker plant’s demand for HP steam production in the steam boilers by approx. 70 %rncompared with the Base case. However, if methanol is produced on-site from gasified biomass, excess heat from thernmethanol production plant can potentially produce enough HP steam to completely off-load the steam boiler.