Technical and Economic Assessments of a novel biomass-to-synthetic natural gas (SNG) process integrating O2-enriched air gasification

To develop a solution for clean gas supply and biomass utilization and indirect renewable power storage, this work proposes a novel SNG process integrating O-2-enriched air gasification with O-2 purity range of 80-96%. Low-cost vacuum pressure swing adsorption (VPSA) is integrated to produce O-2 with purities of 80% and 90%; while cryogenic air separation (CAS) is applied for 96% O-2 purity. Besides SNG, the syngas of the methanation product without CO2 separation (SG) is considered as a new type of safe fuel for rural areas. The technical and economic assessments are successively performed based on simulation data. The effects of important operating variables on technical performances are investigated to determine the optimal values. The overall energy and exergy efficiencies of SG reach 68.37% and 62.59%, respectively, while those of SNG achieve 65.69% and 60.38%, respectively. The equivalent unit product costs of SG and SNG are 1.661 (sic)/Nm(3) and 2.031 (sic)/Nm(3) at base scenario, respectively, which are quite profitable. The sensitivity analysis of the cost indicates that the products has strong cost competitiveness within the actual fluctuations, and the constraints for SG is much looser than that for SNG to gain profit. The process integrating VPSA has obvious advantages in efficiencies and unit production cost, which come with the price of visible disadvantages in CH4 concentration and higher heating value (HHV). The work is a representative reference for the countries lacking natural gas and valuable to guide the development of O-2-enrich air gasifier, process optimization and indirect renewable power storage. (C) 2021 Institution of Chemical Engineers. Published by Elsevier B.V. All rights reserved.

Automated summary

The study proposed a novel SNG process integrating O-2-enriched air gasification with VPSA to develop a solution for clean gas supply and biomass utilization. The SG was considered as a new type of safe fuel with high overall energy and exergy efficiencies, offering good economic benefits.