scholarly journals Influence of Oxidant Agent on Syngas Composition: Gasification of Hazelnut Shells through an Updraft Reactor

Energies ◽  
2019 ◽  
Vol 13 (1) ◽  
pp. 102 ◽  
Author(s):  
Francesco Gallucci ◽  
Raffaele Liberatore ◽  
Luca Sapegno ◽  
Edoardo Volponi ◽  
Paolo Venturini ◽  
...  

This work aims to study the influence of an oxidant agent on syngas quality. A series of tests using air and steam as oxidant agents have been performed and the results compared with those of a pyrolysis test used as a reference. Tests were carried out at Sapienza University of Rome, using an updraft reactor. The reactor was fed with hazelnut shells, waste biomass commonly available in some parts of Italy. Temperature distribution, syngas composition and heating value, and producible energy were measured. Air and steam gasification tests produced about the same amount of syngas flow, but with a different quality. The energy flow in air gasification had the smallest measurement during the experiments. On the contrary, steam gasification produced a syngas flow with higher quality (13.1 MJ/Nm3), leading to the best values of energy flow (about 5.4 MJ/s vs. 3.3 MJ/s in the case of air gasification). From the cold gas efficiency point of view, steam gasification is still the best solution, even considering the effect of the enthalpy associated with the steam injected within the gasification reactor.

2012 ◽  
Vol 66 (7) ◽  
Author(s):  
Afsin Gungor ◽  
Murat Ozbayoglu ◽  
Cosku Kasnakoglu ◽  
Atilla Biyikoglu ◽  
Bekir Uysal

AbstractIn this parametric study, the effects of coal and oxidiser type, air-to-fuel ratio, steam-to-fuel ratio, reactor temperature, and pressure on H2 and CO amounts at the gasifier output, H2/CO, and higher heating value of the syngas produced have been calculated using a coal gasification model. Model simulations have been performed to identify the optimum values which are assumed to be 100 % for both cold gas efficiency and carbon conversion efficiency in the gasification process. From this study, it may be observed that the moisture content of the coal type is of crucial importance for the air gasification process; the O2 content of similar coals (taking into consideration the moisture and H2 content) is of significant importance for the air gasification process. When compared with air gasification, air-steam gasification becomes a more effective coal gasification method. The optimum working condition for air-steam gasification is to carry out the process at one atmosphere. High gasifier temperatures are not needed for the air-steam gasification of coal.


2012 ◽  
Vol 512-515 ◽  
pp. 575-578
Author(s):  
Hsien Chen ◽  
Chiou Liang Lin ◽  
Wun Yue Zeng ◽  
Zi Bin Xu

Catalysis was used to increase the H2 production, syngas heating value, enhanced carbon conversion efficiency and cold gas efficiency during gasification. Due to Cu and Zn were abundant in waste according to previous researches, this research discussed the effect of Cu and Zn on artificial waste gasification. The syngas composition and total lower heating value (LHV) were determined in this study. The results showed that the existence of Cu and Zn increased production of H2 and CO. However, the production of CH4 and CO2 decreased. At same time, total LHV was also increased. Additionally, the different Cu concentration affected gas composition and LHV, but the effect of Zn concentration was not significant.


Energies ◽  
2021 ◽  
Vol 14 (21) ◽  
pp. 7384
Author(s):  
M. Shahabuddin ◽  
Sankar Bhattacharya

This study assessed the entrained flow co-gasification characteristics of coal and biomass using thermodynamic equilibrium modelling. The model was validated against entrained flow gasifier data published in the literature. The gasification performance was evaluated under different operating conditions, such as equivalence ratio, temperature, pressure and coal to biomass ratio. It is observed that the lower heating value (LHV) and cold gas efficiency (CGE) increase with increasing temperature until the process reaches a steady state. The effect of pressure on syngas composition is dominant only at non-steady state conditions (<1100 °C). The variation in syngas composition is minor up to the blending of 50% biomass (PB50). However, the PB50 shows a higher LHV and CGE than pure coal by 12%and 18%, respectively. Overall, biomass blending of up to 50% favours gasification performance with an LHV of 12 MJ/kg and a CGE of 78%.


2020 ◽  
Vol 9 (1) ◽  
pp. 30-35
Author(s):  
Hendriyana Hendriyana

Rice husk is the waste from agriculture industries that has high potential to produce heat and electricity through the gasification process. Air suction mode is new development for updraft rice husk gasification, where blower are placed at output of gasifier. The objective of this research is to examine these new configuration at several equivalence ratio. The equivalence ratio was varied at 32% and 49% to study temperature profile on gasifier, producer gas volumetric flow rate, composition of producer gas, producer gas heating value, cold gas efficiency and carbon conversion. The time needed to consume rice husk and reach an oxidation temperature of more than 700oC for equivalence ratio of 49% is shorter than 32%. Producer gas rate production per unit weight of rice husk increase from  2.03 Nm3/kg and 2.36 Nm3/kg for equivalence ratio of 32% and 49%, respectively. Composition producer gas for equivalence ratio of 32% is 17.67% CO, 15.39% CO2, 2.87% CH4, 10.62% H2 and 53.45% N2 and 49% is 19.46% CO, 5.94% CO2, 0.90% CH4, 3.46% H2 and 70.24% N2. Producer gas heating value for equivalence ratio 32% and 49% is 4.73 MJ/Nm3 and 3.27 MJ/Nm3, respectively. Cold gas efficiency of the gasifier at equivalence ratio 32% is 69% and at 49% is 55%.


Energies ◽  
2020 ◽  
Vol 13 (8) ◽  
pp. 2081
Author(s):  
Md Tanvir Alam ◽  
Se-Won Park ◽  
Sang-Yeop Lee ◽  
Yean-Ouk Jeong ◽  
Anthony De Girolamo ◽  
...  

Solid recovered fuel (SRF) residue, which is leftovers from the SRF manufacturing process, usually is discarded in landfill because of its low heating value and high ash and moisture content. However, it could be used as a fuel after mechanical and biological treatment. Gasification experiments were conducted on treated SRF residue (TSRFR) to assess the viability of syngas production. Efforts were also made to improve the gasification performance by adding low-cost natural minerals such as dolomite and lime as bed material, and by blending with biomass waste. In the case of additive mineral tests, dolomite showed better performance compared to lime, and in the case of biomass blends, a 25 wt% pine sawdust blend with TSRFR showed the best performance. Finally, as an appropriate condition, a combined experiment was conducted at an equivalence ratio (ER) of 0.2 using a 25 wt% pine sawdust blend with TSRFR as a feedstock and dolomite as the bed material. The highest dry gas yield (1.81 Nm3/kg), with the highest amount of syngas (56.72 vol%) and highest lower heating value (9.55 MJ/Nm3) was obtained in this condition. Furthermore, the highest cold gas efficiency (48.64%) and carbon conversion rate (98.87%), and the lowest residue yield (11.56%), tar (0.95 g/Nm3), and gas pollutants content was observed.


Author(s):  
Mehdi Borji ◽  
Kazem Atashkari ◽  
Saba Ghorbani ◽  
Nader Nariman-Zadeh

Numerical analysis of combined heat and power plant consisting of a solid oxide fuel cell and autothermal gasification system has been made for several cases of different composition of fuel relevant to air and steam blown biomass gasification process. Wet wood is fed to the fixed-bed downdraft gasifier and gaseous fuel is produced then after gas cleaning and conditioning can be used in solid oxide fuel cells. The integrated plant is investigated by thermodynamic modeling combining a one-dimensional model of direct internal intermediate planar type solid oxide fuel cell which allows monitoring the temperature gradients along the cell length in different operating conditions and a zero-dimensional autothermal gasifier. The solid oxide fuel cell mathematical model is developed based on gas species mass balances, energy balance, and an electrochemical model beside the kinetics describing internal reforming and water-gas shift reactions. Such a model can be integrated with adiabatic gasification modeling which includes atom balance conservation for assumed gas species and a modified thermodynamic equilibrium analysis. Both gasifier and solid oxide fuel cell models are verified against experimental and previous numerical data available in the literature. Two main parameters, namely modified equivalence ratio and air-to-steam ratio are investigated and the most important cycle parameters such as power, electric and combined heat and power efficiencies, temperature gradients along the cell length, and mole fractions of gaseous species of the produced fuel are analyzed. It has been revealed that any increase in air-to-steam ratio at fixed modified equivalence ratio leads to penalty on cold gas efficiency of the gasifier and both solid oxide fuel cell and combined heat and power plant electric efficiencies. Increased air-to-steam ratio at constant modified equivalence ratio produces a mixture with lower low heating value, higher steam-to-carbon ratio, rich in CO and lower in CH4 content. Under this condition the operating temperature of the cycle and solid oxide fuel cell increases and consequently improves the operating voltage of the cell and combined heat and power efficiency of the plant. On the other hand, results show that gasification with increased modified equivalence ratio at constant air-to-steam ratio produces mixtures richer in CH4 and CO, poorer in H2 with higher low heating value and cold gas efficiency, and lower steam-to-carbon ratio. Such condition improves the electric efficiency of the solid oxide fuel cell and the integrated plant, but the combined heat and power efficiency of the cycle decreases due to decreased operating temperature of the solid oxide fuel cell and the cycle.


2016 ◽  
Vol 25 (41) ◽  
pp. 41
Author(s):  
Juan Fernando Pérez-Bayer ◽  
Rolando Barrera-Zapata ◽  
Carlos Alberto Salazar-Jiménez

<p>The effect of coal rank (from sub-bituminous to semi-anthracite) and type of fuel feeding technology (slurry and dry) on the production of substitute natural gas (SNG) in entrained flow gasifiers is studied. Ten coals from important Colombian mines were selected. The process is modeled under thermochemical equilibrium using Aspen Plus, and its performance is evaluated in function of output parameters that include SNG heating value, Wobbe index, coal conversion efficiency, cold gas efficiency, process efficiency, global efficiency, and SNG production rate, among others. In descending order, the coal-to-SNG process improves energetically with the use of coals with: higher volatile-matter to fixed-carbon ratio, lower ash content, higher C+H/O ratio, and higher coal heating value. The overall energy efficiency of the slurry-feed technology (S-FT) to produce SNG by gasification is 17% higher than the dry-feed technology (D-FT), possibly as a consequence of the higher CH4 concentration in the syngas (around 7 vol. %) when the coal is fed as aqueous slurry. As the simulated SNG meets the natural gas (NG) quality standards in Colombia, the substitute gaseous fuel could be directly transported through pipelines. Therefore, the coal-to-SNG process is a technically feasible and unconventional alternative for NG production.</p>


Energies ◽  
2020 ◽  
Vol 13 (14) ◽  
pp. 3706 ◽  
Author(s):  
Sylvie Valin ◽  
Serge Ravel ◽  
Philippe Pons de Vincent ◽  
Sébastien Thiery ◽  
Hélène Miller ◽  
...  

The aim of this work is to investigate the fluidised bed gasification of several pure and blended feedstock prepared in the form of pellets: oak bark, two bark/wheat straw blends (85/15 and 50/50 wt%) and lignin residue remaining from bioethanol production. Gasification conditions were defined to be representative of dual fluidised bed ones (steam gasification at 850 °C, followed by air combustion of the char). The cold gas efficiency (77–81%), gas composition and tar content (0.9–2.3 g/kgdaf) are close for the gasification of bark and the two bark/wheat straw blends. For lignin residue, the cold gas efficiency is lower (71%), and the tar content is 9.1 g/kgdaf. The agglomeration propensity is much higher for lignin residue than for the other feedstock. This was put into evidence with in-bed temperature measurements at different levels, and confirmed with post-test size screening of the bed material particles. The 50/50 wt% bark/wheat straw blend seems to undergo defluidisation in combustion, however followed by refluidisation of the bed. These findings were also well correlated with a predictive model for defluidisation.


2021 ◽  
Vol 8 (1) ◽  
Author(s):  
Ahmad F ◽  
◽  
Ahmad N ◽  
Asghar U ◽  
Ali A ◽  
...  

Converting rice husk into energy is a promising method of generating renewable energy and reducing greenhouse gas emissions. In this research rice hush is considered as biomass fuel. The characteristics of rice husk gasification were investigated at an Equivalence Ratio (ER) of 0.25–0.38 and a gasifier temperature of 750-870°C in 20 tons per day (TPD) using steam explosion process in fluidized bed gasifier system. Different operation conditions, temperatures and loads, are investigated for their effects on the compositions, calorific properties, gasification efficiencies of syngas. The effects of the critical parameters, namely, Steam-to-Biomass Ratio (S/B), Particle size variation and gasification temperature on the quality of the product gas as well as the gasifier cold gas efficiency were analyzed. This is the new finding in the research. The optimal conditions of the gasification operation were an ER of 0.20 and gasifier temperature of 800°C. The low heating value of the gas product and cold gas efficiency were 1390kcal/Nm³ and 75%, respectively. After passing the generated gas through the gas cleaning units, it was confirmed that the tar in the product gas was removed with an efficiency of 98%. The cleaned product gas was used for the operation of 420kW, gas engine. Pressure loss often occurred at the bottom of the gasifier during the gasification operation; we found that the agglomerates generated by the gasification process caused it. To prevent the pressure loss caused by the agglomerates, the stable control of temperature inside the gasifier is needed and an ash removal device remove agglomerates should be installed to maintain stable long-term operation. This paper leads towards the production of Syngas and further on the electricity from the rice husk, an eminent biomass, copiously available all around the world. Especially in Pakistan, the rice is used abundantly so the raw material is easily available. The gas is produced using the gasification process in dual fluidized gasifier. It is a wonderful alternative to the natural gas with high calorific value. The sulfur contents are quite less compared to natural gas. It also have a good correlation with environment as flue gases emission is negligible relative to other source like coal, wood, plastic, waste etc. Another benefit of this process is the waste management and pollution control. The results are developed by using the detailed analysis of the process values of plants which is generating electricity by rice husk gasification. We learned, all results revealed that the dual fluidized bed gasification is more economical and efficient method compared to all other methods for commercial scale production of syngas. Results are analyzed which imply that the biomass is more gigantic source which replace the fossil fuels and leads towards the green energy in a more economical way. This paper provides an overview of previous works on combustion and gasification of rice husk in atmospheric fluiuidized bed reactors and summarizes the state of the art knowledge. As the high ash content, low bulk density, p characteristics and low ash melting point makes the other types of reactors like grate furnaces and downdraft gasifers either inefficient or unsuitable for rice husk conversion to energy, the fluiuidized bed reactor seems to be the promising choice. The overview shows that the reported results are from only small bench or lab scale units. Although a combustion efficiency of about 80% can normally be attained; the reported values in the literature, which are more than 95%, seem to be in higher order. Combustion intensity of about 530kg/h/m² is reported. It is also technically feasible to gasify rice husk in a fluidized bed reactor to yield combustible producer gas, even with sufficient heating value for application in internal combustion engines.


Author(s):  
Ghulamullah Maitlo ◽  
Rasool Bux Mahar ◽  
Khan Mohammad Brohi

Gasification of coal and biomass using CO2 and air mixture as a carrier gas offers an encouraging way to eliminate the shortage of energy and reduce carbon dioxide emissions. In the present study, the EulerianLagrangian approach was applied to understand the thermochemical conversion behavior of feedstock in entrained flow gasifier. Commercial CFD (Computational Fluid Dynamics) code ANSYS FLUENT®14 was used for the simulation purpose. It was observed that with variation in the CO2 in the air and the CO2 to cotton stalk ratio had a meaningful effect on gasification performance. The different ratios of air and CO2 in varying percentages such as 20% CO2, 30% CO2, 40% CO2, 50% CO2, 60% CO2, 70% CO2 and remaining percentages of air were introduced in entrained flow gasifier. With the increase in CO2 to cotton stalk ratio, the concentration of H2 and CO2 decreased whereas as the concentration of CO improved. It is revealed that mole fraction of CO and CH4 attained maximum when CO2% in the air was 50% and H2 mole fraction was observed maximum at a CO2% in the air was 30%. At 50% CO2 mixture in air, the maximum lower heating value and cold gas efficiency were observed. Therefore, the optimum situation might be 50% percentage CO2 in the gasifying agent for this entrained flow gasifier. Hence an increase in CO and H2, the cold gas efficiency and lower heating value reached the maximum. However, this study provides an appropriate route for energy production using cotton stalks as raw material and will help in designing and operation of the entrained flow reactor. The simulations indicate the thermodynamic limits of gasification and allow for the formulation of the general principles ruling this process. Moreover, no literature is available for the parametric investigations of Pakistani biomass gasification using entrained-flow gasifier. So this is a novel work for Pakistan and will be treated as foundation work for biomass gasification in the country.


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