Effect of Heat Flux Distribution Profile on Hydrogen Concentration in an Allothermal Downdraft Biomass Gasification Process: Modeling Study

2018 ◽  
Vol 141 (3) ◽  
Author(s):  
Yuhan A. Lenis ◽  
Gilles Maag ◽  
Celso Eduardo Lins de Oliveira ◽  
Lesme Corredor ◽  
Marco Sanjuan
Keyword(s):  
Heat Flux ◽  
Hydrogen Production ◽  
Power Systems ◽  
Solar Power ◽  
Fixed Bed ◽  
Tubular Reactor ◽  
Total Power ◽  
Distribution Profile ◽  
Detailed Model ◽  
Gasification Process

Considering the potential of using concentrating solar power systems to supply the heat required for the allothermal gasification process, this study analyzes hydrogen production in such a system by assuming typical radiative heat flux profiles for a receiver of a central tower concentrated solar power (CSP) plant. A detailed model for allothermal gasification in a downdraft fixed bed tubular reactor is proposed. This considers solid and gas phases traveling in parallel flow along the reactor. Results for temperature and gas profile show a reasonable quantitative agreement with experimental works carried out under similar conditions. Aiming to maximize H2 yield, eight Gaussian flux distributions, similar to those typical of CSP systems, each with a total power of 8 kW (average heat flux 20 kW/m2), but with varying peak locations, were analyzed. The results show a maximum producer gas yield and a chemical efficiency of 134.1 kmol/h and 45.9% respectively, with a molar concentration of 47.2% CO, 46.9% H2, 3.3% CH4, and 2.6% CO2 for a distribution peak at z = 1.4 m, thus relatively close to the flue gas outlet. Hydrogen production and gas yield using this configuration were 4% and 2.9% higher than the achieved using the same power but homogeneously distributed. Solar to chemical efficiencies ranged from 38.9% to 45.9%, with a minimum when distribution peak was at the reactor center. These results are due to high temperatures during the latter stage of the process favoring char gasification reactions.

Advanced Hydrogen Generation With Concentrated Solar Power Systems

Solar Energy ◽  
2003 ◽  
Author(s):  
Rainer Tamme ◽  
Reiner Buck ◽  
Stephan Mo¨ller
Keyword(s):  
Hydrogen Production ◽  
Power Systems ◽  
Solar Power ◽  
Hydrogen Generation ◽  
Great Promise ◽  
Economic Approach ◽  
Concentrated Solar Power

Two renewable approaches to advanced solar supported hydrogen generation are presented. For the near and midterm, Hydrogen from solar reforming might be a viable, and economic approach. For the long-term, hydrogen generated by solar supported electrolysis of water will hold great promise for clean hydrogen production.

scholarly journals Experimental Study and Thermodynamic Analysis of Hydrogen Production through a Two-Step Chemical Regenerative Coal Gasification

2019 ◽  
Vol 9 (15) ◽  
pp. 3035 ◽  
Author(s):  
Li ◽  
He ◽  
Li
Keyword(s):  
Hydrogen Production ◽  
Production Process ◽  
Coal Gasification ◽  
Fixed Bed ◽  
H2 Production ◽  
Steam Gasification ◽  
Air Separation ◽  
The Novel ◽  
Separation Unit ◽  
Gasification Process

Hydrogen, as a strategy clean fuel, is receiving more and more attention recently in China, in addition to the policy emphasis on H2. In this work, we conceive of a hydrogen production process based on a chemical regenerative coal gasification. Instead of using a lumped coal gasification as is traditional in the H2 production process, herein we used a two-step gasification process that included coking and char-steam gasification. The sensible heat of syngas accounted for 15–20% of the total energy of coal and was recovered and converted into chemical energy of syngas through thermochemical reactions. Moreover, the air separation unit was eliminated due to the adoption of steam as oxidant. As a result, the efficiency of coal to H2 was enhanced from 58.9% in traditional plant to 71.6% in the novel process. Further, the energy consumption decreased from 183.8 MJ/kg in the traditional plant to 151.2 MJ/kg in the novel process. The components of syngas, H2, and efficiency of gasification are herein investigated through experiments in fixed bed reactors. Thermodynamic performance is presented for both traditional and novel coal to hydrogen plants.

Activities Results of Experiments for Space Solar Power Systems at USEF

2006 ◽  
Author(s):  
Shoichiro Mihara ◽  
Takashi Saito ◽  
Yutaro Kobayashi ◽  
Hiroshi Kanai
Keyword(s):  
Power Systems ◽  
Solar Power ◽  
Space Solar Power

Reliability Index of Wind-Solar Hybrid Power Plants using the Expected Energy Not Supplied Method

2019 ◽  
Vol 8 (4) ◽  
pp. 9449-9456
Keyword(s):  
Power Plant ◽  
Power Systems ◽  
Electricity Market ◽  
Reliability Index ◽  
Power Plants ◽  
Initial Conditions ◽  
Hybrid Plant ◽  
Total Power ◽  
Hybrid Power ◽  
Hybrid Power Plant

This paper proposes the reliability index of wind-solar hybrid power plants using the expected energy not supplied method. The location of this research is wind-solar hybrid power plants Pantai Baru, Bantul, Special Region of Yogyakarta, Indonesia. The method to determine the reliability of the power plant is the expected energy not supplied (EENS) method. This analysis used hybrid plant operational data in 2018. The results of the analysis have been done on the Pantai Baru hybrid power plant about reliability for electric power systems with EENS. The results of this study can be concluded that based on the load duration curve, loads have a load more than the operating kW of the system that is 99 kW. In contrast, the total power contained in the Pantai Baru hybrid power plant is 90 kW. This fact makes the system forced to release the load. The reliability index of the power system in the initial conditions, it produces an EENS value in 2018, resulting in a total value of 2,512% or 449 kW. The EENS value still does not meet the standards set by the National Electricity Market (NEM), which is <0.002% per year. Based on this data, it can be said that the reliability of the New Coast hybrid power generation system in 2018 is in the unreliable category.

scholarly journals Green energy technology from buriti (Mauritia flexuosa L. f.) for Brazilian agro-extractive communities

2021 ◽  
Vol 3 (3) ◽  
Author(s):  
Munique Gonçalves Guimarães ◽  
Rafael Benjamin Werneburg Evaristo ◽  
Augusto César de Mendonça Brasil ◽  
Grace Ferreira Ghesti
Keyword(s):  
Lignin Content ◽  
Fixed Bed ◽  
Thermal Conversion ◽  
Volatile Matter ◽  
Matter Content ◽  
Green Energy ◽  
Fixed Bed Reactor ◽  
Gasification Process ◽  
Mauritia Flexuosa ◽  
Immediate Analysis

AbstractThe present work analyzed the energy generation potential of Buriti (Mauritia flexuosa L. f.) by thermochemical reactions. The experimental part of the study performed immediate analyses, elemental analyses, lignocellulosic analysis, thermogravimetric analysis, calorific values, and syn gas concentrations measurements of the gasification of Buriti in a fixed-bed reactor. Additionally, numerical simulations estimated the syn gas concentrations of the gasification reactions of Buriti. The immediate analysis showed that Buriti has the highest ash content (4.66%) and highest volatile matter content (85%) compared to other Brazilian biomass analyzed, but the higher heating value was only 18.28 MJ.kg−1. The elemental analysis revealed that the oxygen to carbon ratio was 0.51 while hydrogen to carbon ratio was 1.74, indicating a good thermal conversion efficiency. The Lignocellulosic analysis of Buriti resulted in a high content of holocellulose (69.64%), a lignin content of 28.21% and extractives content of 7.52%. The thermogravimetry of the Buriti indicated that the highest mass loss (51.92%) occurred in a temperature range between 150 °C and 370 °C. Lastly, the experimental gasification study in a fixed-bed updraft gasifier resulted in syn gas concentrations of 14.4% of CO, 11.5% of CO2 and 17.5% of H2 while the numerical simulation results confirmed an optimal equivalence ratio of 1.7 to maximize CO and H2 concentrations. Therefore, based on the results presented by the present work, the gasification process is adequate to transform Buriti wastes into energy resources. Graphic abstract

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