Techno-economic assessment of an integrated high pressure chemical-looping process with packed-bed reactors in large scale hydrogen and methanol production

摘要

A full-scale techno-economic analysis of a novel chemical looping based process using dynamically operated packed bed reactors has been carried out for the large-scale production of hydrogen (up to 30,000 Nm(3)/h) and methanol (up to 10,000 tons per day) with inherently integrated CO2 capture. The complete process is carried out in three main reactors, in which the reactions occurring are the dry and steam reforming of natural gas with H2O and CO2, the oxidation of the oxygen carrier (OC) with air and the reduction with a low-grade fuel such as plant off-gases. The thermal balance of the process is achieved by combining the endothermic reforming reaction with the exothermic chemical looping combustion. The chemical looping based process is fully integrated with the separation and synthesis units as well as the power and heat utilities of the two large scale production plants. The two plants are compared with state-of-the-art technologies, including the benchmarks for hydrogen and methanol production from natural gas through steam reforming and auto-thermal reforming. Compared to a conventional H-2 production plant (without CO2 capture), the reforming efficiency is 3% higher, while the required primary energy consumption to separate CO2 is 0.47 MJ(LHV)/kg(CO2) which is significantly lower than that of an amine-based plant (> 1.35 MJ(LHV)/kg(CO2)) and the cost of hydrogen production with the proposed process is 2.19 $/kg with a CO2 avoidance cost of 58.7 $/ton(CO2) (compared to > 70.6 $/ton(CO2) for solvent based plant). In case of methanol production, the carbon conversion is comparable with the best available processes even though CO2 purification and separation (98% capture with > 96% purity) units are included due to the improved energy recovery. By using chemical looping the cost of methanol production decreases overall by 17% compared to the benchmark plant due to the lower investment cost and higher electricity generation resulting overall in a negative CO2 avoidance cost (-303 $/ton(CO2)).