The high efficient synthesis of natural gas from a joint-feedstock of coke-oven gas and pulverized coke via a chemical looping combustion scheme

Natural gas is regarded as a high heating-value and low carbon-footprint fuel, but its supply is deficient and global imbalanced. A technical routine toward synthetic natural gas (SNG), sound in both energy efficiency and environmental impact, is therefore highly demanded. Both coke-oven gas (COG) and pulverized coke (PC) are two major by-products of metallurgical industries. There is the conventional SNG process fed by only COG (CGtSNG), which suffers from less hydrogen utilization and energy efficiency, as well as limited SNG capacity. The driving force on the environmentally-responsible and energy-efficient use of the PC calls for the involvement of state-of-the-art chemical looping combustion (CLC) technology. A new process co-fed by both PC and COG for SNG production via a CLC unit (PCCLC-CGtSNG) is therefore proposed in this study. The PCCLC-derived CO2 can be an effective carbon source to optimize the composition of syngas for high efficient SNG production. The involvement of the CLC in the conventional CGtSNG can achieve intensive material and energy couplings, improve energy and hydrogen utilization efficiencies, and increase SNG productivity. Process modelling results showed that the proposed process possessed about 20% improvement in the hydrogen utilization efficiency and SNG productivity, as well as 6.8% increase of the exergy efficiency, comparing to those of the conventional CGtSNG.