Effect of Steam on Syngas Production in New-Designed Dual-Bed Gasifier

2012 ◽  
Vol 622-623 ◽  
pp. 1125-1129
Author(s):  
Sukrit Pakavechkul ◽  
Prapan Kuchonthara ◽  
Suchada Butnark

In this research, the effect of steam on synthetic fuel production from sawdust in new-designed dual-bed gasification was studied. The dual-bed gasification reactor composed of bubbling/fast fluidized bed combustor and fixed bed gasifier (pyrolysis included) was designed to produce syngas (CO + H2 + CO2 and CH4). The results showed that syngas produced by the dual-bed gasifier with higher steam/carbon ratio also had higher H2 content. In theory, the various reactions expected to occur in the gasification process were boudouard, water-gas and water-gas shift, methanation and steam reforming. Since the operating temperature was only 500-600°C that the steam reformation of methane was desperately to occur due to its endothermic, then CH4 formation still were found. Producer gas from the new gasifier had relatively high quality in terms of heating value per a unit volume compared to other conventional gasifiers. This can be used directly as good gaseous fuel. However, the product gas was not likely served as precursor in chemical industries due to its still low H2/CO ratio and high CH4 concentration.

2015 ◽  
Author(s):  
Luz M. Ahumada ◽  
Arnaldo Verdeza ◽  
Antonio J. Bula

This paper studied, through an experiment design, the significance of particle size, air speed and reactor arrangement for palm shell micro-gasification process in order to optimize the heating value of the syngas obtained. The range of variables was 8 to 13 mm for particle size, 0.8–1.4m/s for air velocity, and updraft or downdraft for the reactor type. It was found that the particle size and air velocity factors were the most significant in the optimization of the output variable, syngas heating value. A heating value of 2.69MJ / Nm3 was obtained using a fixed bed downdraft reactor, with a particle size of 13 mm and 1.4 m/s for air speed; verification of the optimum point of operation under these conditions verified that these operating conditions favor the production of a gas with a high energy value.


2016 ◽  
Vol 1133 ◽  
pp. 654-658 ◽  
Author(s):  
Abrar Inayat ◽  
Murni Melati Ahmad ◽  
Mohamed Ibrahim Abdul Mutalib ◽  
Suzana Yusup ◽  
Zakir Khan

In Malaysia, due to abundance of oil palm waste, it is a good candidate to be used as a feedstock for syngas and hydrogen production. Biomass steam gasification is one of the promising methods for syngas production. This work focuses on the steam gasification with in-situ CO2 capture using CaO as absorbent materials for hydrogen production from palm oil empty fruit bunch (EFB). Three parameters (temperature, steam/biomass ratio and sorbent/biomass ratio) has been studied on the lower heating value (LHV) and higher heating value (HHV) of product gas. The results shows that the current study gives higher value of LHV at lower temperature of 823K. The higher value of LHV is obtained due to the lower concentration of CO2 caused by using CaO as sorbent material. Furthermore, CaO materials enhanced the concentration of concentration of the CO, H2 and CH4 in the product gas. The results are also compared against published data as well.


Author(s):  
Ghulamullah Maitlo ◽  
Rasool Bux Mahar ◽  
Zulfiqar Ali Bhatti ◽  
Imran Nazir

The interest in the thermochemical conversion of biomass for producer gas production since last decade has increased because of the growing attention to the application of sustainable energy resources. Application of biomass resources is a valid alternative to fossil fuels as it is a renewable energy source. The valuable gaseous product obtained through thermochemical conversion of organic material is syngas, whereas the solid product obtained is char. This review deals with the state of the art of biomass gasification technologies and the quality of syngas gathered through the application of different gasifiers along with the effect of different operating parameters on the quality of producer gas. Main steps in gasification process including drying, oxidation, pyrolysis and reduction effects on syngas production and quality are presented in this review. An overview of various types of gasifiers used in lignocellulosic biomass gasification processes, fixed bed and fluidized bed and entrained flow gasifiers are discussed. The effects of various process parameters such as particle size, steam and biomass ratio, equivalence ratio, effects of temperature, pressure and gasifying agents are discussed. Depending on the priorities of several researchers, the optimum value of different anticipated productivities in the gasification process comprising better quality syngas production improved lower heating value, higher syngas production, improved cold gas efficiency, carbon conversion efficiency, production of char and tar have been reviewed.


2012 ◽  
Vol 2012 ◽  
pp. 1-13 ◽  
Author(s):  
C. F. Mhilu

Biomass utilization is becoming a subject of increasing interest as an alternative to clean fuel. A novel gasification process using highly preheated air gasifier using agricultural residue such as sugar bagasse, rice husks, and palm stem widely available in Tanzania is presented. The study examines, irreversibilities making the gasifier the least efficient unit in the gasification process employing a thermodynamic equilibrium model allowing predicting the main product gas composition CO, CO2, H2, and CH4. The derived model equations are computed using the MAPLE process simulation code in MATLAB. The gasification regime is investigated at temperatures ranging from 800 K to 1400 K and at equivalence ratio (ER) values between 0.3 and 0.4. The results obtained conform to the second law efficiency based on chemical exergy yielding maximum values for the types of biomass materials used. These results indicate that the application of preheated air has an effect on the increase of the chemical exergy efficiency of the product gas, hence reducing the level of irreversibility. Similarly, these results show that the combined efficiency based on physical and chemical exergy is low, suggesting that higher irreversibilities are encountered, since the exergy present in the form of physical exergy is utilized to heat the reactants. Such exergy losses can be minimized by altering the ratio of physical and chemical exergy in the syngas production.


Author(s):  
Alice Fourcault ◽  
Fre´de´ric Marias ◽  
Ulysse Michon

Biomass is one of the most important sources of renewable energy. One aim of Biomass gasification is to convert a solid feedstock into a valuable syngas for electricity or liquid fuel production. Actual industrial auto-thermal gasification processes achieve a production of syngas mainly polluted by products such as dust, nitrogen oxides, sulfur dioxide and tars. Tars remain, one of the main drawbacks in using the gasification process since they are capable of condensing at low temperature. This could lead to fouling, corrosion, attrition and abrasion of downstream devices such as gas turbines or engines. Tars are often removed from the syngas, decreasing the internal energy of the syngas itself. These tars are heavy aromatic hydrocarbons whose treatment remains difficult by thermal, catalytic or even physical methods. They can condense or polymerize into more complex structures, and the mechanisms responsible for their degradation are not completely identified and understood. Turboplasma© is a thermal process, proposed by Europlasma. The main principle of operation relies on the use of thermal plasma for the cracking of tars inside a syngas produced in an auto-thermal gasification step. Basically, it consists of a degradation chamber where the syngas is heated by a plasma torch. The plasma plume provides a high temperature gas (around 5000K) to the system and enables heating of the incoming stream (above 1300K) and also generates high temperature zones (above 1600 K) inside the device. Due to both high temperature and long residence times of the syngas in the vessel, cracking of the tars occurs. Finally, the species released are mainly CO and H2, leading to an increase in the Lower Heating Value of the syngas. The work presented here describes the design of a high temperature gasification system assisted by thermal plasma. It was performed using a CFD computation implemented with a full chemical model for the thermal degradation of tars. The objectives were to understand the aerodynamic behavior of the vessel and to propose enhancement in its design. We present here some results of this study.


Author(s):  
Jens Wolf ◽  
Jinyue Yan

In this work, steam-based gasification is investigated as a technology for fuel gas production for topping combustion in a biomass air turbine (BAT) cycle. For different systems, based on flash or conventional pyrolysis, the characteristics of the product gas quality are studied. The gas composition and the heating value of the produced gas are simulated by changing the main system parameters such as the moisture content of the biomass, the operating temperature and the composition of the biomass. A model of the gasification process has been developed to evaluate each process. The model is based on mass conservation, the thermodynamic equilibrium of the water-gas-shift reaction and the methane yield during pyrolysis. A gasification system with flash pyrolysis is identified as a promising technology for fuel gas production for use in topping combustion. The major features of the system are: first, the system provides a gas with a heating value of near to 16 MJ/Nm3 and small amounts of nitrogen gas; second, the application of a water knock out unit eliminates the influence of the water content in the feedstock on the product gas quality; third, the gasification process can be conducted in a tubular reactor within the furnace of the BAT cycle. This reduces the number of reactors and keeps the costs low.


2012 ◽  
Vol 16 (suppl. 1) ◽  
pp. 115-130 ◽  
Author(s):  
Goran Jankes ◽  
Marta Trninic ◽  
Mirjana Stamenic ◽  
Tomislav Simonovic ◽  
Nikola Tanasic ◽  
...  

This paper is a review of the state of the art of biomass gasification and the future of using biomass in Serbia and it presents researches within the project ?The Development of a CHP Plant with Biomass Gasification?. The concept of downdraft demonstration unit coupled with gas engine is adopted. Downdraft fixed-bed gasification is generally favored for CHP, owing to the simple and reliable gasifiers and low content of tar and dust in produced gas. The composition and quantity of gas and the amount of air are defined by modeling biomass residues gasification process. The gas (290-400m3/h for 0.5- 0.7MW biomass input) obtained by gasification at 800oC with air at atmospheric pressure contains 14% H2, 27% CO, 9% CO2, 2% CH4, and 48% N2, and its net heating value is 4.8-6 MJ/Nm3. The expected gasifier efficiency is up to 80%. The review of the work on biomass gasification has shown that the development of technology has reached the mature stage. There are CHP plants with biomass gasification operating as demonstration plants and several gasification demonstration units are successfully oriented to biofuel production. No attempt has been made here to address the economic feasibility of the system. Economics will be the part of a later work as firmer data are acquired.


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.


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