Energy and exergy analysis of gas production from biomass intermittent gasification

Abstract

In this paper, thermochemical biomass intermittent gasification was performed in a fluidized-bed reactor with pure steam as gasification agent. A single fluidized bed two-stage gasification process, also known as intermittent gasification process, which involves the time segregated hybridization of coal-combustion and steam biomass-gasification stages in the same vessel, was employed. This research aims to explore the influences of gasification temperature (T) and steam-biomass ratio (S/B) on composition, energy and exergy distribution, as well as energy and exergy conversion efficiencies of the product gas (biomass-gas). Over the ranges of the test conditions used, the total concentration of H 2 and CO in the biomass-gas varies between 57.9% and 80.8%, and the exergy and energy efficiencies of the biomass-gas are in the ranges of 54.61%-35.52% and 82.91%-60.78%, respectively. The results show that the chemical exergy values of the biomass-gas are 13.50 to 17.71 times as the corresponding physical exergy values, whereas the chemical energy values are 6.91 to 9.45 times as the corresponding physical energy values. The total energy values of the biomass-gas are higher than the corresponding exergy values, this result in higher energy efficiencies of the biomass-gas. Higher temperature contributes to higher CO and H 2 content, physical and chemical energy values, physical and chemical exergy values, as well as energy and exergy efficiencies of the biomass-gas. The steam to biomass ratio is optimal in the intermediate levels for maximal energy and exergy efficiencies of the biomass-gas. V C 2013 AIP Publishing LLC. [http://dx.

Integrated energy-exergy-based evaluation and optimization of a bio-dimethyl ether production system via entrained flow gasification

“…The entire system was simulated and thermodynamically analyzed using ASPEN PLUS, given that most of the studies have remained at the laboratory stage and lack numerous detailed stream 053133- 6 Xiang et al J. Renewable Sustainable Energy 6, 053133 (2014) properties (T, P, enthalpy, entropy, etc.). Note that the related properties of nonconventional components, such as biomass or pyrolytic products, which are absent in the original database, must be manually defined.…”

“…3,4 Most of the studies to date have concentrated on the preparation of biomass-derived syngas and/or investigation of DME synthesis-like catalysts and reaction apparatuses. [5][6][7] Nevertheless, very little attention has been devoted to the systematic study of the comprehensive performance of an integrated bio-DME system, and operating commercial bio-DME plants are currently extremely scarce. To enhance the competition of bio-DME with fossil-based fuels, the integrated bio-DME system should be improved to be as efficient as possible prior to application.…”

Techno-Economic Analysis of Hydrogen and Electricity Production by Biomass Calcium Looping Gasification

“…Finally, Ex H 2 (MW), Ex GT (MW), Ex ST (MW), and Ex AUX (MW) represent the exergy of hydrogen, net power generation from the gas turbine, steam turbine, and power consumed by auxiliary equipment in the whole plant. The exergy of biomass is calculated by Szargut's correlation [38], exergy of hydrogen is determined by Rant's equation [39].…”