Pilot veri?cation of a low-tar two-stage coal gasi?cation process with a ?uidized bed pyrolyzer and ?xed bed
gasi?er
Xi Zeng a ,Fang Wang a ,b ,Hongling Li a ,Yin Wang a ,Li Dong a ,Jian Yu a ,?,Guangwen Xu a ,?
a State Key Laboratory of Multi-Phase Complex Systems,Institute of Process Engineering,Chinese Academy of Sciences,P.O.Box 353,Beijing 100190,China b
School of Chemical and Environmental Engineering,China University of Mining and Technology,Beijing 100083,China
h i g h l i g h t s
The two-stage gasi?cation process proposed consists of FB pyrolyzer and ?xed bed gasi?er. FB pyrolyzer operated at about 850°C and in O 2and steam-containing atmosphere. Char bed layer can remove the tar in fuel gas effectively.
The pilot test fully veri?ed the feasibility of two-stage gasi?cation process.
a r t i c l e i n f o Article history:
Received 24June 2013
Received in revised form 25September 2013Accepted 30October 2013
Available online 22November 2013Keywords:Coal Tar
Two-stage gasi?cation Fluidized bed
Downdraft ?xed bed
a b s t r a c t
A 50kg/h autothermal two-stage gasi?er,consisting of a ?uidized bed (FB)pyrolyzer and a downdraft ?xed-bed gasi?er,has been designed and built according to our previous laboratory researches.In the experiments,lignite gasi?cation was performed in this innovative two-stage gasi?er to demonstrate the process feasibility for clean fuel gas production.The results showed that when keeping the reaction temperatures of the F
B pyrolyzer and downdraft ?xed bed gasi?er respectively at about 860°
C and 1100°C,the tar content in the produced fuel gas from the two-stage gasi?er was effectively lowered to 84mg/Nm 3and the heating value of fuel gas was close to 4.186MJ/Nm https://www.doczj.com/doc/ff2778794.html,pared with the tar pro-duced in the FB pyrolyzer,the tar from the downdraft ?xed bed gasi?er had obviously higher content of light oil components and lower content of heavy components,showing essentially an effective catalytic reforming of tar components by the hot char bed of the downdraft ?xed bed gasi?er.
ó2013Published by Elsevier Ltd.
1.Introduction
As a core technology for clean and high-ef?ciency utilization of coal and other carbon-containing fuels,gasi?cation has been widely used to produce syngas and fuel gas [1,2].The existing gasi?cation technologies are usually categorized into ?xed bed/moving bed gas-i?cation,?uidized bed gasi?cation and entrained ?ow gasi?cation [3].The deep analysis and comparison of the advantages and disad-vantages for the three kinds of gasi?ers can be found in some litera-tures [4–9].Generally,the high-pressure (usually 3.0–4.0MPa)and high-temperature (up to 1700°C)entrained ?ow gasi?ers are suit-able for production of syngas for chemical synthesis with high capacity (e.g.,2000–3000t/d coal),which has also much higher cost.In the aspect of adaptive coal,the entrained ?ow gasi?ers work only with coal having low ash content (e.g.,<10wt.%)and low ash-melt-ing point (e.g.,>1250°C),while the ?xed/moving bed gasi?ers can accept merely large size particles,such as above 20mm for atmo-spheric gasifers and above about 10mm for pressurized Lurgi gasi?-ers.The ?uidized bed gasi?ers are operated usually at about 1000°C,and has the advantage of adapting to high-ash powder coal in sizes of,for example,below 10mm.For the production of industry-use fuel gas with coal,which popularly exists in China and expects low cost,it rarely adopts the high-cost entrained ?ow gasi?ers but mainly the atmospheric ?xed bed gasi?ers (mostly the updraft type)for lump coal or ?uidized gasi?ers for powder coal [10].
As we know,the atmospheric ?xed bed gasi?ers including updraft,downdraft and cross-?ow types,have usually limited capacity,treat only lump coal and suffer from problems related to coal tar that would lead to the problems for the downstream process,such as duct blockage and erosion,catalyst deactivation,environ-mental pollution and so on [11–15].On the other hand,the coal min-ing based on mechanical tools produces only about 30wt.%of lump coal in sizes above 20mm,and more than 60wt.%is powder coal in sizes below 10mm.This would cause serious shortage of the lump coal supply for ?xed bed gasi?ers [16].Bubbling-,circulating-and double ?uidized bed gasi?ers have some obvious advantages over the ?xed bed gasi?ers,such as,uniform and controllable temperature distribution,good fuel ?exibility and large fuel capacity in single unit and so on.However,the problems faced by
0306-2619/$-see front matter ó2013Published by Elsevier Ltd.https://www.doczj.com/doc/ff2778794.html,/10.1016/j.apenergy.2013.10.052
Corresponding authors.Tel./fax:+861082544886.
E-mail addresses:yujian@https://www.doczj.com/doc/ff2778794.html, (J.Yu),gwxu@https://www.doczj.com/doc/ff2778794.html, (G.Xu).
?uidized bed gasi?ers,including high tar and ?nes in producer gas,relatively high cost in investment (comparing to atmospheric ?xed bed gasi?ers),low thermal ef?ciency (due to low reaction tempera-tures at about 1000°C)and so on,seriously hinder their wide appli-cations in fuel gas production.Therefore,developing a novel gasi?cation process adapting to powder feedstock,allowing large treatment capacity,low tar generation and low capital investment is essential and necessary to the upgrading of the coal-base fuel gas production technology.
The so-called two-stage gasi?cation is characterized by physically separating and,in turn,reorganizing at least one of the involved reactions to facilitate the interactive effects between the separated reactions with the other reactions,such as between the fuel pyrolysis and char gasi?cation reactions [17,18].Because of its ef?cient in-bed tar elimination capability at moderate tempera-tures,such as around 900°C,the two-stage gasi?cation is consid-ered to be highly suitable for fuel gas production [19,4,20,21].Up to now,several two-stage gasi?cation processes have been studied.Kim et al.[20]tested a laboratory two-stage reactor consisting of a ?uidized bed gasi?cation zone and a ?xed bed tar cracking zone ?lled with commercial activated carbon.Utilizing this reactor to gasify wood waste,a tar removal ef?ciency about 80%was easily achieved.Dong et al.[21]proposed another biomass two-stage gas-i?cation concept based on integrating a biomass gasi?cation zone and a hot gas cleaning zone in a single reactor.Their primary exper-imental results in a lab-scale facility showed that the tar content in the product gas could be well reduced to below 100mg/Nm 3by using char-based catalysts.A representative two-stage gasi?cation technology has been successfully developed in Technical University of Denmark to gasify wood chips [22].Its process consisted of an externally heated screw pyrolyzer and a downdraft ?xed bed char gasi?er.The producer gas had tar contents below 50mg N à1m à3.Obviously,all of these literature studies fully demonstrated the high ef?ciency of the two-stage gasi?cation process for tar removal.By far,the two-stage gasi?cation technologies have been mainly applied to biomass,and there still exist some limitations including the dif?culty in scale-up,the lack of ?exibility in feedstock and so on [23].Considering all of these,a novel two-stage gasi?cation technology illustrated in Fig.1was proposed by Institute of Process Engineering (IPE),Chinese Academy of Sciences (CAS)[19].The gasi?cation process consists of a ?uidized bed (FB)pyrolyzer and a downdraft ?xed bed char gasi?er as well as tar remover by taking advantage of the hot coal char as catalyst.Coal is fed into and pyro-lyzed in the autothermal FB reactor.All the products of pyrolysis,including pyrolysis gas,char and tar,are forwarded to the down-draft ?xed bed reactor by an over?ow pipe.In the downdraft ?xed bed gasi?er,the char is gasi?ed and the pyrolysis gas and tar are further reformed or cracked by the catalysis of hot https://www.doczj.com/doc/ff2778794.html,pared
to the single-stage gasi?er,in this new two-stage gasi?cation process the drying and pyrolysis of the fed coal are separated from the char gasi?cation and tar elimination to take place in different reactors.Table 1summarizes the major chemical reactions occurring in the pyrolyzer and gasi?er [20,24,25].Because of the adoption of FB pyrolyzer,the new two-stage gasi?cation process is expected to be applicable for powder feedstock (powder coal in this study)and to allow rather large treatment capacity to facil-itate large-scale applications.As a matter of fact,several downdraft ?xed bed reactors can be integrated into a single FB pyrolyzer to realize its large treatment capacity,enabling thus clean and eco-nomic production of coal-base low-tar fuel gas [26].
In terms of enhancing gasi?cation reactions and eliminating tar generation,systematic studies have been performed by us to deter-mine the suitable operating conditions for the autothermal FB pyro-lyzer and downdraft ?xed bed char gasi?er of the preceding two-stage gasi?cation process [19,27].This study is on the basis of our previous fundamental studies and is devoted to verifying this tech-nology and to demonstrating its technical features through per-forming pilot-scale tests gasifying a kind of Chinese lignite.
2.Experimental Section 2.1.Pilot process design
Fundamental studies for the newly proposed two-stage process conceptualized in Fig.1were conducted in a laboratory two-stage gasi?cation apparatus,resulting in understanding the autothermal coal pyrolysis behavior [19]and the catalysis effect of char on tar removal and pyrolysis gas upgrading in the downdraft ?xed bed reactor [27].Table 2shows the results of the proximate,ultimate and ash analyses for the sub-bituminous coal used in our funda-mental study,which was from Xijiang Jimusaer (JMSE)of China.It is clari?ed that the viable operating conditions for the upstream autothermal FB pyrolyzer are at temperatures of about 850°C and having O 2and steam in the reaction (oxidative pyrolysis)atmo-sphere according to an excessive air ratio (ER)of about 0.15and a steam-to-coal mass ratio (S/C)of about 0.15.The viable operating conditions for maximizing the tar removal ef?ciency in the down-draft ?xed bed gasi?er were shown to be at temperatures above 1000°C,ERs of about 0.04and gas residence time in the hot char bed longer than 1.3s.These provide the basis for design and con-struction of the pilot gasi?cation plant.
This study designed and built an autothermal pilot system with a coal treatment capacity of 50kg/h and a total height of 6m according to the preceding conditional data from the laboratory studies.Fig.2(a)and (b)shows a process diagram and a picture of the plant,respectively.This autothermal testing apparatus mainly included a screw feeder,a FB pyrolyzer,a downdraft ?xed bed gasi?er,two air compressors and two gas supplying systems (for two reactors),a water seal,a fuel gas burner and two sampling ports for measuring the gas of pyrolysis and gasi?cation,respec-tively.An over?ow pipe was used to connect the FB and downdraft ?xed bed reactors.The main reaction zones of the FB pyrolyzer and downdraft ?xed bed gasi?er were cuboid structure,which have in-ner dimensions of 450mm long,250mm wide and 650mm high for the pyrolyzer and 600mm long,600mm wide and,650mm high for the gasi?er,respectively.Fig.3shows the detailed con?g-urations and dimensions of the FB pyrolyzer and downdraft ?xed bed gasi?er,indicating that the reactors were all with refractory for ensuring the plant for autothermal operation.During the experiment,the temperature and pressure inside the FB pyrolyzer and downdraft ?xed bed gasi?er were measured by K -type ther-mocouples and pressure transducers.The positions of the thermo-couples and pressure sensors are indicated in Fig.3(a)and (b).
Fuel
N 2, O 2, Steam
O 2, Steam
Gas
Gas
Ash
Pyrolyzer
Gasifier
conceptual diagram of the proposed new two-stage gasi?cation 10X.Zeng et al./Applied Energy 115(2014)9–16
2.2.Pilot process operation
For the pilot test,a kind of lignite from Inner Mongolia Xilinhaote (XLHT)of China was adopted.Before utilization,the coal sample was crushed,sieved to the sizes below 4.0mm.Tables 2and 3show the results of proximate and ultimate analyses and size distribution measurement for the XLHT coal,respectively.One can see that the JMSE and XLHT coals have similar compositions in the proximate and ultimate analyses,but the XLHT coal has higher ash and sulfur contents.The sizes in Table 3show that the pilot tests used ?ne coal with sizes smaller than 4mm,and the major part of the tested coal was in 1–4mm.
In operation of the pilot plant,the pyrolyzer and gasi?er were ?rst heated by burning wood charcoal to raise their tempera-tures to a desired value.Then the coal dried in open air was in turn fed into the pyrolyzer through the screw feeder at a gradually increased rate to maintain and also raise further their temperatures.In this process,the air ?ow into the pyrolyzer was regulated to ensure a good ?uidization for the coal particles.The produced char,pyrolysis gas and gaseous tar in the pyrolyzer were conveyed into the downstream gasi?er to form a char bed layer.When the char in the gasi?er reached the desired va-lue,air was supplied into this reactor.At last,the temperatures of the pyrolyzer and gasi?er were controlled at about 850°C and 950°C,respectively.
Fig.4shows a schematic diagram of the adopted tar collection and gas cleanup system.To prevent tar condensation,the temperature of the pipelines from the exit of the pyrolyzer and gasi?er to the sampling port was maintained to be above 330°C.After stable running of the two-stage gasi?er was reached,the sampling valves were opened to suck the gas products from the FB pyrolyzer or downdraft ?xed bed gasi?er by a sampling pump.The sucked gas passed through a pipe cooling system (à20°C)and several washing bottles in an ice-water bath to collect the tar and clean the gas.The non-condensable gas was metered and puri?ed further in a silica gel column to remove moisture and impurities before analyzed using a gas chromatograph (micro-GC,Agilent 3000).After the test,the tar-containing liquid collected from both condensation and washing the pipelines with acetone was treated in turn by dehydration in MgSO 4,?ltration to remove ash and ace-
Table 1
Major reactions occurring in pyrolyzer and gasi?er.Reactor Reaction Reaction equation
Reaction Heat a kJ/mol Number Pyrolyzer
Pyrolysis Coal ?Char +Tar +Pyrolysis gas (H 2,CO,CO 2,CH 4,C 2H 4...)1Oxidation C +O 2?CO 2à405.82Gasi?cation C +0.5O 2?CO
à110.73Tar cracking Tar ?CO 2+CO +H 2+CH 4+C 2H 4...4Gasi?er
Oxidation C +O 2?CO 2à405.82Gasi?cation C +0.5O 2?CO à110.73Boudouard C +CO 2?2CO +172.15Water–gas
C +H 2O ?CO +H 2+131.36Water–gas shift CO +H 2O ?CO 2+H 2
à41.2
7Tar cracking Tar ?CO 2+CO +H 2+CH 4+C 2H 4...4Reforming
Tar +O 2?CO 2+CO +H 2O
8Tar +H 2O ?CO +H 2+C 2H 4...
9
a
The signs ‘‘+’’and ‘‘à’’denotes the endothermic and exothermic reactions,respectively.
Table 2
Proximate and ultimate analyses for the JMSE coal and XLHT coal.Coal
Proximate analysis (wt.%)Ultimate analysis (wt.%)LHV (MJ/kg)
M ad
A ad V ad FC ad C daf H daf S daf O daf JMSE 14.57.629.248.776.9 4.20.317.626.33XLHT
12.5
14.6
31.7
41.2
75.1
4.3
1.1
19.5
20.42ad:Air-dried basis;daf:dry and ash-free basis.
(b)
T/P
T/P T/P
T/P T/P Coal
FB
T/P
Screw Feeder
Air compressor
DFB
Water Seal
Burner
Sampling Port
(a)
Fig.2.A process diagram (a)and a picture the adopted pilot test apparatus.
X.Zeng et al./Applied Energy 115(2014)9–16
11
tone evaporation at30°C at negative pressure to remove acetone measuring the mass of the generated tar[28].
2.3.Analysis and characterization
The yield of fuel gas was estimated on the basis of the composition analyzed in the micro GC by taking the rate of well-controlled nitrogen stream as the tracer gas.The distillation fraction characteristics of the tar sample was measured via simu-lated distillation in a high-temperature gas chromatograph(Agi-lent7890A)using N2as the carrier gas according to
distillation method ASTMD6352.Based on correlating the boiling points of reference samples temperatures or retention times,this analyzer hydrocarbon distribution in weight percent
boiling point ranges[29].By far,this
used in the petroleum industry.In this study,
tars with lower boiling temperatures(<350
using a GC-MS(HP6890),for which a high
1.0mL/min was adopted as the carrier gas
and discussion
Temperature and pressure drop in two reactors
the new two-stage gasi?cation pilot apparatus
using air as the gasi?cation reagent and
operation time was up to100h,and each test whole day.Fig.5shows the typical operating
FB pyrolyzer(upside plot)and downdraft
two typical operations,the cases1and operation,the temperatures of the main reaction
pyrolyzer and gasi?er were maintained at
(b) Downdraft fixed bed gasifier.
(a) Fluidized bed (FB) pyrolyzer
3.Con?guration and dimension of the(a)FB pyrolyzer and(b)downdraft?xed
gasi?er for the50kg/h pilot two-stage gasi?cation apparatus.
Table3
Particle size distribution of the tested XLHT coal.
Particle size(mm)0.5<0.5–11–22–33–4
Mass fraction(wt.%) 2.5 5.329.722.640.0
schematic diagram for the tar collection and gas cleanup
5.Time-series temperatures in pyrolyzer and gasi?er for two operation cases.
Fig.6(a)and(b)display the pressure drops across the pyrolyzer (a)and gasi?er(b)for the case1.After feeding coal into the prolyz-er for a while,the tar-containing pyrolysis gas and hot char gener-ated in the pyrolyzer began to be supplied into the gasi?er through the over?ow pipe.The pressure drop in the pyrolyzer?rst rapidly increased and then reached a steady value when the char started to over?ow from the?uidized bed.For the gasi?er,the pressure drop elevated sharply with the gradually more pyrolysis gas from the pyrolyzer into the gasi?er,and it then increased slightly because of the stable pyrolysis gas?ow and over?ow of char.Because the gasi?er did not have ash discharge in the experiment,the pressure gasi?cation and tar catalytic reforming as well as cracking.As shown in Fig.7,the variation of the temperature in pyrolyzer from 800°C(case2)to860°C(case1)decreased the fractions of H2and CO in the produced gas,whereas it increased the CH4and CO2frac-tions.The reactions of coal pyrolysis and secondary decomposition of tar must be intensi?ed at the higher temperatures,thus releasing more light gases,such as H2,CO,CH4,CO2,H2O and light hydrocarbons.However,the pyrolysis reactions are endothermic and their required thermal energy has to be supplied by combustion and or oxidation reaction of the produced char and combustible gases[30].This should lower the fractions of the effective gas components,especially H2and CO because of the higher oxidation kinetic rates.
Fig.8shows the time-series variations of composition and its corresponding lower heating value(LHV)for the fuel gas from the exit of the downstream gasi?er.The data further demonstrated a good stability of the pilot plant operation for both cases.Table5 lists further the average concentration values of each component and the LHVs for cases1and2.The volume fractions of H2,CH4 and CO2in case1were lower than that in case2,but the CO fraction was higher for case1,making the higher heating value of the fuel gas for case1.Since the main gasi?cation reactions such as reaction
Table4
Experimental conditions for case1and case2.
Condition parameters Case1Case2
Feeding rate(kg/h)5050
Air inlet temperature(°C)1010
Air?ow rate for pyrolyzer(m3/h)5046
Air?ow rate for gasi?er(m3/h)2325
Reaction temperature in pyrolyzer(°C)860800
Reaction temperature in Gasi?er(°C)11001000
Time-series of pressure drop across the pyrolyzer and gasi?er for the Fig.7.Pyrolysis gas composition from pyrolyzer in case1and case
X.Zeng et al./Applied Energy115(2014)9–1613
Comparing to the tar contents at the outlets of pyrolyzer and gasi?er for each of the two cases,one can see clearly that after passing through the gasi?er,most of the tar produced in the pyro-lyzer was reformed by the hot char bed.For the case1,the tar con-tent in the fuel gas decreased sharply from1257mg/Nm3to 84mg/Nm3,achieving a tar removal ef?ciency of up to93%. Fig.10shows the colors of the corresponding tar liquids obtained by washing(scrubbing)the gas from the pyrolysis and gasi?cation stages in the cases1and2.The difference in the color clearly shows that most of the tar species in the product gas of the pyro-lyzer was removed by letting the gas pass through the hot char
that the liquid remained basically in white after continuous running for a few hours((a)to(b)for case1and(c)to(d)for This was in good agreement with our previous fundamental at laboratory[19,27]and also with some other literature
[31,32].It veri?es further the effectiveness of tar removal by the tested two-stage gasi?cation technology.
3.4.Evolution of tar compositions
Fig.11shows the distillation fractions of tars obtained from the two stages of the pilot test in case1.In Fig.11(a)the tar from the pyrolyzer had four big fractions grouped according to the temperatures below170°C,in200–210°C,in280–360°C and above360°C.The tar from the second stage,which is the gasi?er loaded with char,had only two fractions at the boiling points be-low170°C and in280–360°C.Moreover,the fraction below
https://www.doczj.com/doc/ff2778794.html,position and LHV of the produced fuel gas in cases1and2.
Table5
Average gas composition and LHV of fuel gas for cases1and case2.
Cases H2(%)N2(%)CO(%)CO2(%)CH4(%)LHV(MJ/Nm
Case110.9058.9218.4310.65 1.10 3.898
Case211.8258.9813.3416.52 1.50 3.507
Fig.9.Tar content in the produced fuel gas for the?rst and second stages.
samples collected at the outlets of pyrolyzer and gasi?er for
from pyrolyzer for case1,(b)tar from gasi?er for case1, case2,and(d)tar from gasi?er for case2.
11.Distillation range of tar from the?rst and second stages for case
170°C accounts for about75wt.%,while that above360°C was very low.These clari?ed that the char bed in the second stage caused the tar to be obviously lighter with lower boiling points.
Fig.11(b)compared further the contents of every distillation fractions given by the simulative distillation for the tars from the two stages.Passing through the second stage,the contents of the light oil and anthracene oil obviously increased(especially the for-mer)but those of the carbolic oil,washing oil and pitch decreased by some extent.The decrease in the pitch content was extremely large,which might contribute to the increase in the anthracene oil content.All these results show that the tests for both case1 and case2did not thoroughly remove the generated tar from the produced gas,showing that further optimizing the two-stage gas-i?cation process is highly necessary in the view of producing fuel gas with rather deeper tar elimination.
The tar fraction with boiling points below300°C was further analyzed using GC-MS to clarify how the tar nature varied in pass-ing through the hot char bed,and Fig.12shows the result obtained for the case1.To see the change in tar composition more clearly, the spectrum for acetone solvent(numbered0)is not shown in the spectra of Fig.12.Fig.12(a)for the pyrolyzer shows that the tar components were mainly polycyclic aromatic hydrocarbons including anthracene,phenanthrene,?uoranthene and so on.After catalytic reforming over the char bed,there are more tar species by having more small-molecular substances,while the content of polycyclic aromatic hydrocarbons obviously decreased.When hot product gas containing tar past through the char bed,its heavy components is easier to be absorbed onto the surface or active sites of the porous char particles.This prolongs the residence time of tar matters inside the reactor to have more thorough catalytic elimi-nation of tar.The eliminated tar is converted usually into gas com-ponents,while a part becomes coke as carbon deposition. Regarding this mechanism of tar removal over char,we are per-forming more studies to understand the involved fundamental chemical steps and also the variation in char features.
4.Conclusions
A new two-stage gasi?cation process consisting of a?uidized-bed(FB)pyrolyzer and a downdraft?xed-bed gasi?er has been pro-posed to gasify low-rank crushed powder coal for production of fuel gas with low tar content.On the basis of a series of fundamental studies at laboratory,an autothermal pilot plant treating about 50kg/h coal was built and commissioned for steady operation to gasify a kind of lignite with air.The temperature of pyrolysis and gasi?cation(also tar elimination)were at800–900°C and 1000–1100°C,respectively.The obtained typical results from the continuous steady operations of the pilot plant fully demonstrated the technology feasibility of the devised new two-stage gasi?cation process.Although the tested small pilot plant had higher heat loss and the used gasi?cation agent(air)in the tests was not preheated, the tar presenting in the produced fuel gas was lowered to a level of 84mg/Nm3,and the lower heating value(LHV)of the product gas reached 4.186MJ/Nm3.Consequently,rather improved perfor-mance would be expected for the industrial two-stage gasi?cation process,which will have de?nitely the lower tar content in the fuel gas and the higher LHV.
Acknowledgements
The authors are grateful to the?nancial supports of National Basic Research Program of China(2011CB201304);Sate Instrumen-tation Grant(2011YQ120039),National Science Foundation of China(21306209)and CAS Strategic Coal Research Program (XDA07050400).
References
[1]Nakata T,Sato T,Wang H,Kusunoki T,Furubayashi T.Modeling technological
learning and its application for clean coal technologies in Japan.Appl Energy 2011;88:330–6.
[2]Xiao RR,Chen XL,Wang FC,Yu GS.Pyrolysis pretreatment of biomass for
entrained-?ow gasi?cation.Appl Energy2010;87:149–55.
[3]Collot AG.Matching gasi?cation technologies to coal properties.Int J Coal Geol
2006;65:191–212.
[4]Hamel S,Hasselbach H,Weil S,Krumm W.Autothermal two-stage gasi?cation
of low-density waste-derived fuels.Energy2007;32:95–107.
[5]Arena U.Process and technological aspects of municipal solid waste
gasi?cation:a review.Waste Manage2012;32:625–39.
[6]McKendry P.Energy production from biomass(part3):gasi?cation
technologies.Bioresour Technol2002;83:55–63.
[7]Balat M,Kirtay E,Balat H.Main routes for the thermo-conversion of biomass
into fuels and chemicals.Part2:Gasi?cation systems.Energy Convers Manage 2009;50:3158–68.
[8]Ruiz JA,Juárez MC,Morales MP,Mu?oz P,Mendívil MA.Biomass gasi?cation
for electricity generation:review of current technology barriers.Renew Sustain Energy Rev2013;18:174–83.
[9]Ahmedl TY,Ahmad MM,Yusup S,Inayat A,Khan Z.Mathematical and
computational approaches for design of biomass gasi?cation for hydrogen production:a review.Renew Sustain Energy Rev2012;16:2304–15.
[10]Stiegel GJ,Maxwell RC.Gasi?cation technologies:the path to clean,affordable
energy in the21st century.Fuel Process Technol2001;71:79–97.
[11]Hoeven TAV,Lange HCD,Steenhoven AAV.Analysis of hydrogen in?uence on
tar removal by partial oxidation.Fuel2006;85:1101–10.
[12]Munajat NF,Erlich C,Fakhrai R,Fransson TH.In?uence of water vapour and tar
compound on laminar?ame speed of gasi?ed biomass gas.Appl Energy 2012;98:114–21.
[13]Chen HF,Namioka T,Yoshikawa K.Characteristics of tar,NOx precursors and
their absorption performance with different scrubbing solvents during the pyrolysis of sewage sludge.Appl Energy2011;88:5032–41.
[14]Anis S,Zainal ZA.Tar reduction in biomass producer gas via mechanical,
catalytic and thermal methods:a review.Renew Sustain Energy Rev 2011;15:2355–77.
[15]Xu CB,Donald J,Byambajav E,Ohtsuka Y.Recent advances in catalysts for hot-
gas removal of tar and NH3from biomass.Fuel2010;89:1784–95.
[16]Wang B,Tian YP.The utility method and gasi?cation process of low quality
?ne coal.Guangzhou Chem Indust2009;37:197–9.
(a)
(b)
https://www.doczj.com/doc/ff2778794.html,position of GC-MS analysis for the tars from the(a)?rst and(b)second
X.Zeng et al./Applied Energy115(2014)9–1615
[17]Zhang JW,Wang Y,Dong L,Gao SQ,Xu GW.Decoupling gasi?cation:
approach principle and technology justi?cation.Energy Fules2010;24: 6223–32.
[18]Matsuoka K,Hosokai S,Kuramoto K,Suzuki Y.Enhancement of coal char
gasi?cation using a pyrolyzer-gasi?er isolated circulating?uidized bed gasi?cation system.Fuel Process Technol2013;109:43–8.
[19]Zeng X,Wang Y,Yu J,Wu SS,Zhong M,Xu SP,et al.Coal pyrolysis in a?uidized
bed for adapting to a two-stage gasi?cation process.Energy Fuels 2011;25:1092–8.
[20]Kim JW,Mun TY,Kim JO,Kim JO.Air gasi?cation of mixed plastic wastes using
a two-stage gasi?er for the production of producer gas with low tar and a high
caloric value.Fuel2011;90:2266–72.
[21]Dong L,Asadullah M,Zhang S,Wang XS,Wu HW,Li CZ.An advanced biomass
gasi?cation technology with integrated catalytic hot gas cleaning:Part I.
Technology and initial experimental results in a lab-scale facility.Fuel 2013;108:409–16.
[22]Henriksen U,Ahrenfeldt J,Jensen TK,G?bel B,Bentzen JD,Hindsgaul C,et al.
The design,construction and operation of a75kW two-stage gasi?er.Energy 2006;31:1542–53.
[23]Ahrenfeldt J,Thomsen TP,Henriksen U,Clausen LR.Biomass gasi?cation
cogeneration–a review of state of the art technology and near future perspectives.Appl Therm Eng2013;50:1407–17.
[24]Wang Y,Yoshikawa K,Namioka T,Hashimoto Y.Performance optimization of
two-staged gasi?cation system for woody biomass.Fuel Process Technol 2007;88:243–50.[25]Devi L,Ptasinski K,Janssen F.A review of the primary measures for tar
elimination in biomass gasi?cation processes.Biomass Bioenery 2003;24:125–40.
[26]Guang WX,Liu XH,Gao SQ.Method and device integrating lean oxygen
?uidized bed combustion and?xed bed gasi?cation for clean fuel gas, production[P].CN1916123;2005.
[27]Zeng X,Wang Y,Yu J,Wu SS,Han JZ,Xu SP,et al.Gas upgrading in a downdraft
?xed bed reactor downstream of a?uidized bed coal pyrolyzer.Energy Fuels 2011;25:5242–9.
[28]Li CS,Suzuki K.Tar property,analysis,reforming mechanism and model for
biomass gasi?cation–an overview.Renew Sustain Energy Rev 2009;13:594–604.
[29]Green LE,Schmauch LJ,Worman JC.Simulated distillation by gas
chromatography.Anal Chem1964;36(8):1512–6.
[30]Vélez JF,Chejne F,Valdés CF,Emery EJ,Londo?o CA.Co-gasi?cation of
Colombian coal and biomass in?uidized bed:an experimental study.Fuel 2009;88:424–30.
[31]Mun TY,Seon PG,Kim JS.Production of a producer gas from woody waste via
air gasi?cation using activated carbon and a two-stage gasi?er and characterization of tar.Fuel2010;89:3226–34.
[32]Zhang S,Asadullah M,Dong L,Tay HL,Li CZ.An advanced biomass gasi?cation
technology with integrated catalytic hot gas cleaning.Part II:Tar reforming using char as a catalyst or as a catalyst support.Fuel2013;112:646–53.
16X.Zeng et al./Applied Energy115(2014)9–16