Effect of the type of gasifying agent on gas composition in a bubbling fluidized bed reactor

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inst i tute

Effect of the type of gasifying agent on gas composition in a bubblingfluidized bed reactor

Emir Aydar*, Serhat Gul 1, Namık Unlu 1, Fehmi Akgun 2, Haydar Livatyali 3

TUBITAK Marmara Research Center Gebze Campus Energy Institute, 41470 Kocaeli, Turkey

a r t i c l e i n f o

Article history:Received 15 January 2013Accepted 29 April 2013

Keywords:Coal gasificationBubbling fluidized bedSynthesis raw gasSteamEquivalence ratio

* Corresponding author. Tel.: þ90 262 677 2820; faE-mail addresses: [email protected] (E. Ay

[email protected] (H. Livatyali).1 Tel.: þ90 262 677 2791; fax: þ90 262 641 2309.2 Tel.: þ90 262 677 2771; fax: þ90 262 641 2309.3 Tel.: þ90 262 677 2824; fax: þ90 262 641 2309.

http://dx.doi.org/10.1016/j.joei.2014.02.0041743-9671/� Energy Institute.

Please cite this article in press as: E. Aydar,Journal of the Energy Institute (2014), http:

a b s t r a c t

It is commonly accepted that gasification of coal has a high potential for a more sustainable and cleanway of coal utilization. In recent years, research and development in coal gasification areas are mainlyfocused on the synthetic raw gas production, raw gas cleaning and, utilization of synthesis gas fordifferent areas such as electricity, liquid fuels and chemicals productions within the concept of poly-generation applications. The most important parameter in the design phase of the gasification processis the quality of the synthetic raw gas that depends on various parameters such as gasifier reactor itself,type of gasification agent and operational conditions. In this work, coal gasification has been investigatedin a laboratory scale atmospheric pressure bubbling fluidized bed reactor, with a focus on the influence ofthe gasification agents on the gas composition in the synthesis raw gas. Several tests were performed atcontinuous coal feeding of several kg/h. Gas quality (contents in H2, CO, CO2, CH4, O2) was analyzed byusing online gas analyzer through experiments. Coal was crushed to a size below 1 mm. It was found thatthe gas produced through experiments had a maximum energy content of 5.28 MJ/Nm3 at a bed tem-perature of approximately 800 �C, with the equivalence ratio at 0.23 based on air as a gasification agentfor the coal feedstock. Furthermore, with the addition of steam, the yield of hydrogen increases in thesynthesis gas with respect to the water–gas shift reaction. It was also found that the gas producedthrough experiments had a maximum energy content of 9.21 MJ/Nm3 at a bed temperature range ofapproximately 800–950 �C, with the equivalence ratio at 0.21 based on steam and oxygen mixtures asgasification agents for the coal feedstock. The influence of gasification agents, operational conditions ofgasifier, etc. on the quality of synthetic raw gas, gas production efficiency of gasifier and coal conversionratio are discussed in details.

� Energy Institute.

1. Introduction

The oil crisis and global environmental problems have become critical challenge worldwide; therefore, more and more attention hasbeen paid to the clean coal technologies, among which the coal gasification is one of the critical ones for efficient utilization of coal.Compared to the coal combustion, there is a lower reaction rate in coal gasification process.

Coal gasification is becoming an attractive alternative for power generation since it offers higher efficiency and improved environmentalperformance than conventional pulverized fuel technology [1]. Various types of gasifiers such as moving bed, entrained flow, and fluidizedbeds have been employed by industry, but intensive research activities for technology development and improvement are still ongoing.Fluidized bed reactors are much more suitable for low rank coal having mostly high ash, high sulfur and high moisture. Therefore, fluidizedbed gasifiers have the potential advantage that low rank coals can be processedmore efficiently than in conventional pulverized coal boilers.The higher efficiency that coal gasification offers could be used as a strategy for carbon abatement in the future. A potential disadvantage of

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fluidized bed coal gasification is low carbon conversion in comparison to other types of gasifiers. This is due to its low operating temperature(900–1050 �C) and rapid loss of reactivity [1,2].

Gasification process has been used for different application areas such as power generation, gaseous and liquid fuel production orchemical production. But the production of gas having high calorific value, high H2 and CO content together with high fuel conversion ratioand gas efficiency are themain targets to be realized in the design and operation. In the recent years, several studies have been performed tovalidate the design and to optimize the operation conditions of coal and/or biomass gasification processes.

The fluidized bed gasifier is one of widely applied technologies, because a longer residence time, uniform temperature distribution, highmass and heat transfer rates could be achieved in such kind of reactor. So, different studies on coal and/or biomass gasification in fluidizedbeds have been realized. Tomeczek et al. [3] performed an experimental study on coal gasification under the gasification medium of airand steam–air mixtures at atmospheric pressure. They reported that the gas heating values varied between 2.9 and 3.5 MJ/m3 using air and4.1–4.5MJ/m3 using air–steammixtures.Watkinson et al. [4] realized some experiments with different coals in a fluidized bed gasifier underthe gasification medium of air and steam. They found that the heating values of gas varied between 1.6 and 4.2 MJ/m3. Ocampoa et al. [5]made an experimental study for the gasification of Titiribi coal in a pilot scale fluidized bed reactor at atmospheric pressure with air andsteammixtures and they obtained the heating value of gas as 3.3 MJ/m3. Karimipour et al. [6] performed a series of experiments to study theeffect of three operating factors, namely, coal feedrate, coal particle size, and steam/O2 ratio, and their interactions on the quality of syngasproduced from fluidized bed gasification of lignite coal. They found that the higher heating value of syngas was between 3.77 and 4.21 MJ/m3. Karatas et al. [7] carried out gasification tests by using a laboratory scale bubbling fluidized bed gasifier under air atmosphere. Theyinvestigated the effects of equivalence ratio, coal type and calcined dolomite on gas quality and properties. They found that the lowerheating value syngas for different coals under the test conditions were between 4.36 and 6.16 MJ/Nm3. Kim et al. [8] performed anexperimental study on the gasification of a sub-bituminous coal in a down-flow reactor. When the steam/coal ratio increased from 0.23 to0.86, they observed a decrease in the heating value of product gas from 9.0 to 6.4 MJ/m3 in the gasification region due to reduction ofcombustible gas. A similar trend was reported for bituminous and anthracite coals by Zhou [9] but the higher heating values of gas werebetween 2.2 and 3.4 MJ/Nm3.

In addition, different studies have also been performed in fluidized bed gasifier by using different coal, biomass and co-gasification ofdifferent feedstocks [10–18]. A comprehensive comparison data for some reported result was given by Taba et al. [19]. The experimentalstudies aremostly based on the gasificationmedium of air, or air/steam condition. However, few researchers reported the coal gasification ina fluidized bed under O2/steam atmosphere.

In this paper, the results of two different gasification agents obtained in a laboratory scale bubbling fluidized bed gasifier are presented.The activities have been performed within an ongoing project, supported by TUBITAK under the frame of 1007 Research Grant Program“Liquid Fuel Production from Biomass and Coal Blends”. In the project, it is aimed to develop the technologies on liquid fuel production fromcoal and biomass blends and demonstrate the results on a pilot scale integrated system. Within this frame, R&D activities on the relatedtechnologies such as gasification, gas cleaning, gas separation and conditioning and Fischer-Tropsch synthesis and conversion of syngas intoliquid fuels are ongoing within the projects.

The performance of gasifier depends on many design and operational parameters such as fuel type, reaction temperature, pressure,gasification agents etc. This paper presents the results obtained in the gasification of Turkish Soma lignite in a fluidized bed gasifier atatmospheric pressure with the presence of air or oxygen/steam mixture to explore the effects of operating parameters on gasificationperformance and to evaluate the efficiency of raw gas production for gasification process.

2. Methodology

2.1. Coal feedstock and its characterization

The coal used in the current study was lignite obtained from Soma, a county of the Manisa Province in the Aegean region of Turkey. Theraw feed containing high amount of moisture was air dried. The dried feed was then crashed. The ultimate and proximate analyses of coaltested are presented in Table 1.

2.2. Experimental facility

A schematic diagram of the lab-scale bubbling fluidized-bed gasifier used in the experiments appears in Fig.1. The reactor is split into twosections as shown in Fig. 2: a bed section and a freeboard section. The fluidized bed reactor is formed by two vertical stainless steel tubes

Table 1Proximate and ultimate analysis of coal (at original basis).

Proximate analysisMoisture wt.% 13.75Ash wt.% 24.61Volatile wt.% 34.52Fixed carbon wt.% 27.12Lower heating value kJ/kg 15,786.23Ultimate analysisCarbon wt.% 48.4Hydrogen wt.% 2.84Oxygen wt.% 11.5Nitrogen wt.% 0.94Sulfur wt.% 1.16

Please cite this article in press as: E. Aydar, et al., Effect of the type of gasifying agent on gas composition in a bubbling fluidized bed reactor,Journal of the Energy Institute (2014), http://dx.doi.org/10.1016/j.joei.2014.02.004

Fig. 1. Scheme of the gasification facility.

E. Aydar et al. / Journal of the Energy Institute xxx (2014) 1–8 3


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having different size and connected by means of a conical adapter. The lower tube has an internal diameter of 73.6 mm and a height of1010 mm whereas the upper tube is 97.18 mm internal diameter and 1800 mm high.

The bed is fluidized with air provided by a screw type air compressor. The air flow rate during gasification is 6 Nm3/h corresponding to asuperficial velocity of 1.1 m/s at a bed temperature of 800 �C. The primary fluidization gas enters the bottom of the reactor in the plenum andthen flows through a drilled-hole distributor plate. The gas distributor at the bottom of the fluidizing column has a circular shape. The gas

Fig. 2. Schematic representation of the lab-scale gasifier.




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passes through 1519 holes, 1.2 mm internal diameter that is arranged in 44 regular rows along the circular surface. The inert bed materialused is silica sand and has a mean particle size of 250–500 mmwith a density of 1520 kg/m3, which belongs to Geldart Group B particles. Thestatic bed height wasmaintained at 380mm. The coal is continuously fed into the reactor through a screw feeder conveyer equippedwith aninverter. Fuel feeding system is shown in Fig. 3.

The fuel is under-bed fed into the reactor by means of a screw conveyor, 130 mm above the circular distributor. The fuel flow rate isregulated by means of an additional screw feeder, rotating at changeable rate and directly connected to a sealed fuel hopper. After thereactor is heated to reaction temperatures, solid fuel can be processed. The particulate-laden exhaust stream exits the reactor through thefreeboard and passes through a series of cyclones. The product gases are sampled and analyzed with on-line gas analyzer for H2, O2, CO, C02,CH4, H2S. Gaseous samples are also taken in bags subjected to a gas chromatograph analysis for determination of major hydrocarbon speciessuch as H2S, NH3, COS. After sampling and flowmeasurement, the gases are flared and vented. A flare equipped with a LPG pilot flame burnsthe syngas coming from the gasifier upstream the chimney. To remove the ashes generated by the fuel introduced in the reactor, a screwconveyor shown in Fig. 4 is located under the reactor.

To compare with results of air gasification, both oxygen and steam were used as gasification agents. Oxygen is supplied by a bundle oftwelve cylinders. Desired air and oxygen flow rate is regulated with mass flow controller. Steam is supplied by a steam generator. Steam isregulated with orifice meter. The temperature of different operating zones of the gasifier was also monitored by several type Kthermocouples.

2.3. Test procedure

Gasification tests were carried out at atmospheric pressure. Initially the fluidized bed reactor above the gas distributor plate was loadedwith silica sand. Before coal is introduced into the reactor, the bed inside reactor is heated up to about 400 �C which is the ignition tem-perature of coal thanks to the electrical resistances which are located outside of the reactor and gasification agents supply line in presence ofan air stream of around 6 m3/h through the distributor plate and the bed. As the temperature of reactor reached to 400 �C, the coal feedingwas started. To avoid the pyrolysis of coal inside the screw feeder, an auxiliary nitrogen stream was used during the process. Enough air issent to the reactor in order to completely burn the available fuel. Bed temperature decreases immediately due to the drying and pyrolysisprocesses, and bed temperature increases significantly within 2 min. Therefore, combustion takes place inside reactor in order to reach thedesired temperature (800–900 �C) for gasification process. The dirty outlet gas containing ash, char, tar and dust particles entered the

Fig. 3. Fuel feeding system.


Fig. 4. Ash removal system.



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cyclone separator. The cyclone removed ash and chars from the hot gas and derived them into the bin connected to the cyclone. After the fineparticles were separated in the cyclone, the part of product gas flow was passed through a cooling water trap for drying and cleaning. Thenthe dry and clean gas was sent to on-line gas analyzer to detect H2, O2, CH4, CO and CO2 contents.

3. Results and discussions

Equivalence ratio (ER) is a crucial factor affecting gas quality. ER is defined as the actual oxygen to fuel ratio divided by the stoichiometricoxygen to fuel ratio needed for complete combustion. In case of air gasification, fixing the air flow rate at 6 Nm3/h and feeding rate is variedto explore the impact of ER on the composition of synthesis gas. Variation of two parameters of carbon conversion efficiency and cold gasefficiency could be used to investigate the effects of air/coal ratio on LHV of fuel gas. The definitions of carbon conversion efficiency and coldgasification efficiency are shown in equations (1) and (2), respectively.

Carbon conversion efficiency ¼ total reacted carbon in the system ðkgÞtotal carbon fed in the system ðkgÞ (1)

Cold gas efficiency ¼ LHV of fuel gas�kJ=Nm3�� fuel gas production

�Nm3=kg

�

low heating value of coal fed in the system ðkJ=kgÞ (2)

With a variation from 0.23 to 0.33, the effect of ER on experimental results is given in Table 2. Measurements were recorded during theexperiments. ER of 0.23 was repeated two times and ER of 0.33 was repeated four times. Main idea is to see the repeatability.

As explained earlier, relatively higher temperatures enhanced the evolution of combustible gases especially H2 and CO which in turnresulted in an increase in LHV of the synthesis gas. The H2 and CO yields increase with increasing ER from 0.23 to 0.33, whereas the yield ofCO2 decreases due to enhancement of carbon conversion as shown in Table 2.

As ERwas raised from 0.23 to 0.33, the CO level also increased from 8.8 to 15.2%. An increase in the CO content could possibly be due to anincrease in the Boudouard reaction rate, which would be responsible for the conversion rate of char into gaseous components.


Table 2Operating conditions, gas composition and yields during air gasification.

Sample 1 2 3 4 5 6

Gasification agent Air Air Air Air Air AirOperating conditionsAir velocity inside reactor (m/s) 1.1 1.1 1.1 1.1 1.1 1.1Air flow rate (Nm3/h) 6 6 6 6 6 6Fuel flow rate (kg/h) 5.51 5.51 3.92 3.92 3.92 3.92Bed temperature (�C) 800–814 800–812 800–810 794–800 787–800 792–800Equivalence ratio 0.23 0.23 0.33 0.33 0.33 0.33Gas compositionO2 (% by vol.) 0.5 0.5 0.5 0.4 0.3 0.3N2 (% by vol., dry basis) 59.1 54.3 59.9 59.6 58.8 56.3CO2 (% by vol.) 14.2 13.8 12.8 12.5 12.0 11.2CH4 (% by vol.) 8.4 6.9 3.5 2.7 2.7 2.0CO (% by vol.) 8.8 10.1 10.9 12.0 13.3 15.2H2 (% by vol.) 9.0 14.4 12.4 12.8 12.9 15.0H2O (% by vol.) 21.7 13.8 9.8 9.3 8.9 5.8H2S (ppm) 575 575 575 575 575 575YieldsLHV (MJ/Nm3) 5.08 5.28 3.96 3.85 4.03 4.24Cold gas efficiency 43.7 49.5 47.2 46.2 48.9 53.9Carbon conversion (%) 50.6 54.0 60.8 61.1 63.7 67.5Synthesis gas flow rate (Nm3/h, dry) 8.0 8.7 7.9 8.0 8.1 8.4



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Simultaneously, the CO2 content of the synthesis gas decreases from 14.2% to 11.2%, due to again the Boudouard reaction through which theyield of CO2 is converted to CO.

In addition, the CH4 content of the synthesis gas decreases from 8.4% to 2.0%. This reveals that conditions inside the reactor are closer topyrolysis rather than gasification. When ER is less than optimum value specified for gasification, pyrolysis reactions may become moredominant.

Table 2 indicates that hydrogen content increases from 9.0% to 15.0% by increasing ER from 0.23 to 0.33. Such increase in the H2 level ofthe synthesis gas was due to the improvement of water-gas shift reaction involved in the gasification process.

The lower heating value of the synthesis gas varied between 3.85 and 5.28 MJ/Nm3. This was probably caused by the higher methanecontent at lower ER values and gasification process approaches pyrolysis analysis. Following the increase in ER the methane contentdecreased. The results obtained from these tests are in the range of data reported by other researchers [4–8,19] for gasification of differentcoals.

Here, the carbon conversion efficiency is defined as the fraction of carbon element in feed fuel that could be converted into thecomposition of the synthesis gas. The total carbon conversion into gases lies between 50.6 and 67.5% with a variation of ER from 0.23 to 0.33.It can be seen that complete conversion of carbon in the fuel could only be achieved in combinationwith optimum ER.When the value of ERis too small, unburned carbon does not have enough O2 to react with and consequently a decrease in the carbon conversion efficiency takesplace.

As ER increased from 0.23 to 0.33, as expected, the cold gas efficiency increased. More air was put into the gasifier to satisfy the needs ofthe gasification process of the coal and its product. However, with air being further input, cold gasification efficiency decreases.

At the condition of oxygen/steam gasification, fixing the oxygen, steam and fuel flow rates at 3 m3/h, 1.6 m3/h and 14.42 kg/h,respectively, the composition of synthesis gas was investigated. Experimental results were given in Table 3.

At the condition of oxygen/steam gasification, ER value has been fixed as 0.21 due to temperature control difficulties during oxygen/steam gasification experiments. Therefore, variable parameters such as oxygen, steam and fuel flow rates were kept constant.

The average value of CO2 in the synthesis gas is 38.2%, and the average value of H2 inside the synthesis gas is 35.7%, whereas the averagevalue of CO in the synthesis gas is 15.6%. In comparison with air gasification, the amount of CO2 and H2 increased substantially but theamount of CO increased slightly. Therefore, increasing the steam rate increases the production of H2 and CO2 at the expense of CO via thewater gas shift reaction.

In case of air gasification, the variation of the low heating value of the synthesis gas with different equivalence ratio was also investigatedduring the experimental studies and it was plotted. The variation of LHV of fuel gas produced according to equivalence ratio is shown inFig. 5.

Figure shows that lower heating value of synthesis gas decreases by increasing ER. Such increase in the lower heating value of thesynthesis gas was due to the improvement of oxidization reactions involved in the combustion process.

At the condition of coal oxygen/steam gasification, the impact of oxygen/steam agents on hydrogen and carbon monoxide yields wasinvestigated by fixing the ER. Experimental results are given in Table 3. ER of 0.21 was repeated four times. Main idea is to see therepeatability.

It was seen that heating value of the gaseous product is nearly doubled by applying oxygen/steam gasification other than air gasifi-cation. H2 and CO are two most important gas species in the gaseous products, whose content and ratio are two indicators to determinegas quality. H2/CO ratio of the synthesis gas is about 2.3. This ratio is more than 2.1 which is optimum ratio needed for F-T synthesisreactor. Thus a gas conditioning process is not necessary under the oxygen/steam gasification to adjust the H2/CO ratio required for F-Tsynthesis reactor.

Agglomeration of the bed material was observed during oxygen/steam gasification, especially at high temperatures. Increase of the bedtemperature beyond to approximately 900 �C for silica sand, resulted in the growth of bed particle. Therefore, the flow rate of oxygen andsteam should be carefully controlled in order to maintain good fluidization state inside the reactor.


Table 3Operating conditions, gas composition and yields during oxygen and steam gasification.

Sample 1 2 3 4

Gasification agent Oxygen/steam Oxygen/steam Oxygen/steam Oxygen/steamOperating conditionsAir velocity inside reactor (m/s) 0.8 0.8 0.8 0.8Oxygen flow rate (m3/h) 3 3 3 3Steam flow rate (m3/h) 1.6 1.6 1.6 1.6Fuel flow rate (kg/h) 14.42 14.42 14.42 14.42Bed temperature (�C) 800–900 800–950 800–988 800–900Equivalence ratio 0.21 0.21 0.21 0.21Gas compositionO2 (% by vol.) 0.33 0.34 0.33 0.33N2 (% by vol., dry basis) 1.27 0.76 1.07 0.47CO2 (% by vol.) 41.6 39.5 39.5 40.1CH4 (% by vol.) 9.1 9.2 9.5 9.4CO (% by vol.) 16.1 17.3 16.7 16.3H2 (% by vol.) 34.4 36 35.8 36.4H2O (% by vol.) 18.80 16.28 16.40 15.80YieldsLHV (MJ/Nm3) 8.84 9.20 9.21 9.19Cold gas efficiency 59.0 62.5 62.7 62.5Carbon conversion (%) 80.0 80.0 80.0 80.0Synthesis gas flow rate (Nm3/h, dry) 16.3 16.6 16.6 16.6

Fig. 5. The variation of low heating value of fuel gas produced with the ER.



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4. Conclusions

Gasification of low-rank coal has been investigated in a laboratory scale atmospheric pressure bubbling fluidized bed gasifier. The effectof ER and different gasification agents on the quality of the synthesis gas was assessed. The lower heating value of syngas produced fromlignite was found to be 5.28 MJ/m3 when the value of ER was 0.23 during air gasification.

In the process of coal gasification in a bubbling fluidized bed gasifier, compared to air gasification, hydrogen yield by volume is improvedthrough application of oxygen/steam gasification. Further, gas heating value is nearly doubled. The maximum lower heating value of syngasreaches 9.21 MJ/Nm3 at an equivalence ratio of 0.21 during oxygen/steam gasification. However, the agglomeration evolved at high tem-peratures was the main concern during the oxygen/steam gasification. Thus, during the oxygen/steam gasification experiments should beperformed at temperatures below approximately 900 �C to ensure the avoidance of any agglomeration.

Acknowledgments

This study has been realized within the “Liquid Fuel Production from Biomass and Coal Blends” project. TUBITAK is greatly acknowledgedfor the support of this project under the “Support Programme for Research Projects of Public Institutions” (the contract number 108G043).

References

[1] M.P. Aznar, M.A. Caballero, J. Gil, J.A. Martin, J. Corella, Commercial steam reforming catalysts to improve biomass gasification with steam–oxygen mixtures. 2. catalytictar removal, Ind. Eng. Chem. Res. 37 (1998) 2668–2680.

[2] J. Corella, A. Orio, J.M. Toledo, Biomass gasification with air in a fluidized bed: exhaustive tar elimination with commercial steam reforming catalysts, Energy Fuels 13(1999) 702–709.

[3] J. Tomeczek, W. Kudzia, B. Gradon, L. Remarczyk, The influence of geometrical factors and feedstock on gasification in a high temperature fluidised bed, Can. J. Chem.Engng 65 (1987) 785.

[4] A.P. Watkinson, G. Cheng, C.B. Prakash, Comparison of coal gasification in fluidised and spouted beds, Can. J. Chem. Engng 61 (1983) 468.[5] A. Ocampoa, E. Arenasb, F. Chejnea, J. Espinela, C. Londonoa, J. Aguirrea, J.D. Pereza, An experimental study on gasification of Colombian coal in fluidised bed, Fuel 82

(2003) 161–164.[6] S. Karimipour, R. Gerspacher, R. Gupta, R.J. Spiteri, Study of factors affecting syngas quality and their interactions in fluidizedbed gasification of lignite coal, Fuel 103

(2013) 308–320.




1234567891011121314151617

[7] H. Karatas, H. Olgun, F. Akgun, Coal and coal and calcined dolomite gasification experiments in a bubbling fluidized bed gasifier under air atmosphere, Fuel Process.Technol. 106 (2013) 666–672.

[8] Y.J. Kim, S.H. Lee, S.D. Kim, Coal gasification characteristics in a downer reactor, Fuel 80 (2001) 1915–1922.[9] H. Zhou, Air and steam coal partial gasification in an atmospheric fluidized bed, Energy Fuels 19 (2005) 1619–1623.

[10] S. Rapagna, A. Latif, Steam gasification of almond shells in a fluidised bed reactor: the influence of temperature and particle size on product yield and distribution,Biomass Bioenergy 12 (1997) 281–288.

[11] A.A. Boateng, W.P. Walawender, L.T. Fan, C.S. Chee, Fluidized-bed steam gasification of rice hull, Bioresour. Technol. 40 (1992) 235–239.[12] I. Narváez, A. Orío, M.P. Aznar, J. Corella, Biomass gasification with air in an atmospheric bubbling fluidized bed. Effects of six operational variables on the quality of the

produced raw gas, Ind. Eng. Chem. Res. 35 (1996) 2110–2120.[13] S. Turn, C. Kinoshita, Z. Zhang, D. Ishimura, J. Zhou, An experimental investigation of hydrogen production from biomass gasification, Int. J. Hydrogen Energy 23 (1998)

641–648.[14] S. Rapagna, N. Jand, A. Kiennemann, P.U. Foscolo, Steam-gasification of biomass in a fluidised-bed of olivine particles, Biomass Bioenergy 19 (2000) 187–197.[15] K. Kumabe, T. Hanaoka, S. Fujimoto, T. Minowa, K. Sakanishi, Co-gasification of woody biomass and coal with air and steam, Fuel 86 (2007) 684–689.[16] J.F. Gonzalez, S. Roman, D. Bragado, M. Calderon, Investigation on the reactions influencing biomass air and air/steam gasification for hydrogen production, Fuel Process.

Technol. 89 (2008) 764–772.[17] C. Hanping, L. Bin, Y. Haiping, Y. Guolai, Z. Shihong, Experimental investigation of biomass gasification in a fluidized bed reactor, Energy Fuels 22 (2008) 3493–3498.[18] A. Al-Kassir, J. Ganan, A. Marcos, H. Olgun, Experimental study of gasification of biomass residues for electrical energy generation, Int. J. Energy Res. 36 (2) (2012)

241–248.[19] L.E. Taba, M.F. Irfan, W.A.M.W. Daud, M.H. Chakrabarti, The effect of temperature on various parameters in coal, biomass and CO-gasification: a review, Renew. Sustain.

Energy Rev. 16 (2012) 5584–5596.


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Effect of the type of gasifying agent on gas composition in a bubbling fluidized bed reactor