Effect Analysis on Combustion and Emission Characteristics

Research ArticleEffect Analysis on Combustion and Emission Characteristics of aRotary Burner Fueled by Biomass Pellet Fuel

Guohai Jia 1 Lijun Li 1 and D M Zhang2

1College of Mechanical and Electrical Engineering Central South University of Forestry and Technology Changsha 410004 China2Department of Industrial Technology California State University Fresno CA 93740-8002 USA

Correspondence should be addressed to Lijun Li junlili1122163com

Received 11 October 2019 Revised 20 January 2020 Accepted 6 March 2020 Published 21 July 2020

Guest Editor Yaojie Tu

Copyright copy 2020 Guohai Jia et al +is is an open access article distributed under the Creative Commons Attribution Licensewhich permits unrestricted use distribution and reproduction in any medium provided the original work is properly cited

A biomass pellet rotary burner was chosen as the research object in order to study the influence of excess air coefficient on thecombustion phenomenon of biomass rotary burner the finite element simulation model of a biomass rotary burner wasestablished and simulation results of a biomass rotary burner were verified by the experiment +e computational fluid dynamicssoftware was applied to simulate the combustion characteristics of biomass rotary burner in a steady-state condition and the effectof excess air coefficient on temperature field and component concentration field in biomass rotary burner was analyzed +eresults show that the flue gas flow rate inside the burner gradually increases with the increase of air velocity the area with largetemperature is mainly concentrated in the middle region of the rotary burner and the maximum combustion temperature alsoappeared in the middle region of the combustion chamber and the formation area of CO decreases with the increase of excess aircoefficient CO2 is mainly concentrated in the middle region of the burner and the CO2 generating region decreases with theincrease of excess air coefficient +e experimental value of the combustion temperature of the biomass rotary burner is in goodagreement with the simulation results

1 Introduction

With the rapid development of modern economy andtechnology the energy crisis and air pollution from thecombustion of fossil fuels have become increasingly serious[1ndash3] In order to meet the requirements of resource andenvironment problems many researches had been done toimprove combustion technologies and look for alternativesto replace fossil fuels [4 5] Biomass pellet fuel is a typicalbiomass solid forming fuel with high efficiency clean easyto ignition CO2 near-zero emissions and so on [6ndash8] It canreplace coal and other fossil fuels used in cooking heatingand other civilian areas and boiler combustion powergeneration and other industrial areas [9 10]

In recent years biomass pellet fuel is being developedrapidly in the EU North America and China [11ndash13]Another advantage of biomass pellet fuel is that it can beused in small boilers hot blast furnaces and heating fur-naces +e automatic control system is used to achieve the

continuous combustion of biomass pellet fuel burner Afteryears of research biomass pellet burners are being developedrapidly+ese burners mainly use wood pellets as fuelWoodpellets have many advantages such as high calorific valuelow ash content high ash melting point and being not easyto slag after combustion [14 15]

Khodaei et al [16] addressed a comparative CFD-basedanalysis of different drying models Several submodels weresimulated to investigate the evaporation process of differentgeometries based on standard densified wood pelletsBuchmayr et al [17] presented an accurate time-efficientCFD approach for small-scale biomass combustion systemsequipped with enhanced air staging +e model can handlethe high amount of biomass tars in the primary combustionproduct at very low primary air ratios Gas phase com-bustion in the freeboard was performed by the SteadyFlamelet Model (SFM) together with a detailed heptanecombustion mechanism Farokhi et al [18] presented acomputational study to evaluate the influence of turbulence

HindawiJournal of ChemistryVolume 2020 Article ID 3618382 12 pageshttpsdoiorg10115520203618382

and combustion models as well as chemistry schemes on thecombustion of an 8ndash11 kW small lab-scale biomass furnaceFagerstrom et al [19] used a macro-TGA reactor to de-termine the release of ash forming elements during devo-latilization and char combustion of single pellets Soft woodand wheat straw were combusted at two temperatures(700degC and 1000degC) and the residual ashes were collectedand analyzed for morphology elemental and phase com-position Roy et al [20] presented combustion and emissionresults obtained using a prototype pellet furnace with7ndash32 kW capacity (designed for burning high ash contentpellet fuels) for four biomass pellets one grass pellet andthree wood pellets Fuel property gas emissions and furnaceefficiency are compared Vicente and Alves [21] presented anextensive tabulation of particulate matter emission factorsobtained worldwide and critically evaluated Hendersonet al [22] explained how local economies can benefit fromwood pellet manufacturing by expressing the economicmultiplier effect of wood pellet plant operations in terms ofemployment wages and salaries and value-added in each ofthe 13 states in the US South Nunes et al [23] studiedseveral studies on the torrefaction of biomass for heat andpower applications in the literature which need to bereviewed and analyzed for further actions in the field be-cause significant gaps remain in the understanding of thebiomass torrefaction process which necessitate furtherstudy mainly concerning the characterization of the tor-refaction chemical reactions investigation of equipmentperformance and design and elucidation of supply chainimpacts Mobini et al [24] used a dynamic simulationmodeling approach to assess the integration of torrefactioninto the wood pellet production and distribution supplychain +e developed a model that combined discrete eventand discrete rate simulation approaches and allowed con-sidering uncertainties interdependencies and resourceconstraints along the supply chain which were usuallysimplified or ignored in static and deterministic models

Proskurina et al [25] presented an overview of the currentstatus of the Finnish wood pellet business and discussed themain opportunities and challenges facing the future devel-opment of the industry Coelho et al [26] studied several basecase power plants and hybrid biomassCSP options woodgasification refuse-derived fuel pellets biogas from awastewater anaerobic digester and biogas from a landfill andnatural gas Roni et al [27] investigated the existing cofiringplants with technologies and the availability of biomass re-sources in different countries of the world Finally this papersummarized the major global biomass cofiring initiatives andthe prospects of biomass cofiring in securing renewable en-ergy targets Toklu [28] showed that there is an importantbiomass energy potential for climate change mitigation andenergy sustainability in Turkey Proskurina et al [29] eval-uated the potential of torrefied biomass in different industriesboth power and nonpower generation industries and con-sidered the impact of such use on the international biomassmarket Carvalho et al [30] compared different technologiessuch as CFB air and oxygen gasification dual fluidized bed(DFB) steam gasification and bio-synthetic natural gas (bio-SNG) production focusing on the use of the product gas in an

iron ore pelletizing process located in the Southeast of BrazilGarcıa et al [31] analyzed thirteen alternative raw biomasssamples and compared themwith briquette wood pellets andcharcoal and considered the data of their proximate ultimateand calorimetric analysis and physical properties Silva et al[32] evaluated the application potential of torrefaction in thesolid fuelrsquos production from lignocellulosic biomasses inBrazil Xu et al [33] evaluated the reductions in PM25organic carbon (OC) and elemental carbon (EC) emissions bycomparing emission factors (EFs) among 19 combinations ofbiofuelresidential stove types measured using a dilutionsampling system Ahn and Jang [34] manufactured and testeda prototype of a 230 kW class wood pellet boiler employing afour-step grate Ndibe et al [35] investigated cofiring char-acteristics of torrefied biomass fuels at 50 thermal shareswith coals and 100 combustion cases Kraszkiewicz et al[36] analyzed the results of the CO NO and SO2 emissionfrom burning pellets of oil cake rape straw and birch sawdustin the low-temperature water boiler of the top combustionChai and Saffron [37] optimized the biomass upgrading depotcapacity and biomass feedstock moisture to obtain theminimum production cost at the depot gate to producewoody biofuels

In this paper a biomass pellet rotary burner with the spiralcleaning and slagging device was chosen as the research objectin order to study the influence of excess air coefficient on thecombustion efficiency According to the combustion char-acteristics of the biomass (wood pellet) a high-efficiencydouble-layer combustion drum device has been designed toachieve a better flow distribution in this study +e flowvelocity distribution characteristics in the burner have animportant effect on the combustion efficiency of the biomass(wood pellet)+e flow field distribution and combustion fielddistribution of the new biomass rotary burner are studiedwhich can reduce the test workload and shorten the designcycle +e CFD software was applied to simulate the com-bustion characteristics of biomass rotary burner in steadycondition and the effects of the excess air ratio on thetemperature field and component concentration field in thebiomass rotary burner were analyzed

2 Numerical Model

21 Physical Model of Biomass Rotary Burner In order toimprove the thermal efficiency of the biomass rotary burner arotary combustion chamber has been used in the biomassrotary burner for reducing the pollutants A screw feed device isused to control the appropriate amount of biomass (woodpellet) +e schematic diagram of the biomass rotary burner isshown in Figure 1 which is mainly constituted by the spiralfeeding mechanism rotary combustion chamber small com-bustion chamber connecting flange and other components

When the burner is working the biomass pellets are fedfrom the feed spiral tube into the rotary combustionchamber +e air is blown into the rotary combustionchamber through the secondary air pores to make thebiomass particles burn completely +e combustion char-acteristics of the burner in the steady state are studied in thepaper

2 Journal of Chemistry

22 Mathematical Model In this work the combustioncharacteristics of the biomass rotary burner were studied byFluent software In the numerical calculation the turbulentflow adopts the k-ε equation model and the P-1 model wasused to simulate the radiative heat transfer +e discretephase particle trajectory was adopted A power-diffusionlimiting model was used in the stochastic tracking model forcombustion A two-step competitive reaction model wasadopted for calculating volatile pyrolysis and a mixturefractionprobability density function (PDF) was used forsimulating gas phase turbulent combustion

In the fluid simulation of biomass rotary burner it isregarded as steady-state turbulent motion+e flow and heattransfer conservation equations of mass momentum andenergy are as follows

+e mass conservation equation is

div(ρU) 0 (1)

where ρ is the fluid density and U is the fluid velocity vector+e momentum conservation equation is

div(ρuU) div(μgradu) minuszp

zx+ Su

div(ρvU) div(μgradv) minuszp

zy+ Sv

div(ρwU) div(μgradw) minuszp

zz+ Sw

⎧⎪⎪⎪⎪⎪⎪⎪⎪⎪⎪⎪⎪⎨

⎪⎪⎪⎪⎪⎪⎪⎪⎪⎪⎪⎪⎩

(2)

where p is the fluid pressure μ is the dynamic viscosity andSu Sv and Sw are the generalized source terms for themomentum conservation equation

+e energy conservation equation is

div(ρUT) divh

cp

gradT1113888 1113889 + ST (3)

where cp is the specific heat capacity of fluid T is the fluidtemperature h is the heat transfer coefficient of fluid and Stthe is viscous dissipation term

+e turbulence kinetic equation and the turbulencestress equation which reflect the influence of the turbulencepulsation on flow can be obtained by the k-ε equation in thefollowing form

z ρkui( 1113857

zxi

z

zxj

μ +μt

σk

1113888 1113889zk

zxj

1113890 1113891 + Gk minus ρε + Sk (4)

where k is the turbulent kinetic energy μt is the turbulentviscosity Gk is the generation term of the turbulent kinetic kcaused by mean velocity gradient Sk is the source term ofturbulent kinetic energy and σk is the Prandtl numbercorresponding to the turbulent kinetic k

z ρεui( 1113857

zxi

z

zxj

μ +μt

σε1113888 1113889

zεzxj

1113890 1113891 +εk

C1εGk minus ρεG2ε( 1113857 + Sε

(5)

where ε is the turbulent dissipation rate Sε is the turbulentdissipation source σε is the Prandtl number corresponding tothe turbulent kinetic energy dissipation ε andC1ε andC2ε are theempirical constants σk 10 σε 13 C1ε 144 and C2ε 192

In the mixed fraction model the instantaneous ther-mochemical parameters of the fluid are related to the mixingfraction +e mixing fraction can be calculated by equation(6) according to the atomic mass fraction of the fuel andoxidant including the inert component

f Zi minus Ziox

Zifuel minus Ziox (6)

where Zi is the elemental mass fraction of element i thesubscript ox is the value at the inlet of oxidant stream andfuel is the value at the inlet of the fuel stream +e mixingfraction is the local mass fraction of all components (CO2H2O O2 etc) including the combusted and unburned fuelstream elements (C H etc) +e average (time average)mixed fraction and its mean square equation are

z

zt(ρf) + nabla middot (ρVf) nabla middot

μt

σt

nablaf1113888 1113889 + Sm

z

ztρfprime21113874 1113875 + nabla middot ρVfprime21113874 1113875 nabla middot

μt

σt

nablafprime21113888 1113889 + Cgμt nabla2f1113872 1113873

minus Cdρεk

middot fprime2

(7)

whereV is the average velocity vector ms μt is the turbulentviscosity kg(mmiddots) σk is the turbulent Prandtl number Sm isthe source term caused by chemical reaction kg(m3middots) and

1 2 3 4

567

1-Rotary combustion chamber2-Stirring rib3-Secondary air pores4-Blower fan

5-Spiral feeding mechanism6-Small combustion chamber7-First air pores

Figure 1 Schematic of biomass pellet rotary burner

Journal of Chemistry 3

Cg and Cd are the model constants which are 286 and 200respectively

For radiant heat flow qr it can be expressed by

qr 1

3 a + σs( 1113857 minus Cσs

nablaG (8)

where a is the absorption coefficient σs is the scatteringcoefficient G is the incident radiation Wm2 and C is thelinear anisotropic phase function coefficient

Introducing the parameter Γ 1[3 (a+ σs)minusCσs]equation (8) can be turned into

qr minusΓnablaG (9)

+e transport equation for G is

nabla(ΓnablaG) minus aG + 4aσT4

SG (10)

where σ is the Stephen-Boltzmann constant 567times10minus8W(m2middotK4) and SG is the source term of user-defined radiationWm2

When using the P-1 model the local radiation intensityis used to solve this equation Equation (11) can be calculatedby combining equations (9) and (10)

minusnablaqr aG minus 4aσT4 (11)

where minusqr is an expression that can be directly substitutedinto the energy equation to obtain a heat source due toradiation

+e precipitation of biomass volatiles was simulatedusing a two-competing-rate model and the parameter wasdetermined based on the properties of biomass

mv(t)

1 minus fw01113872 1113873mp0 minus ma

1113946t

0α1R1 + α2R2( 1113857

middot exp minus 1113946t

0R1 + R2( 1113857dt1113888 1113889dt

(12)

where mv(t) is the mass of volatiles precipitated at time t kgfw0 is the initial volatile mass fraction of the particles mp 0is the initial particle mass of the jet source kg ma is the ashcontent of the particles kg α1 and α2 are production ratefactors and R1 and R2 are competitive precipitation rateconstants controlling the precipitation rate in differenttemperature ranges Ri Aiexp (minusEiRTp) kg(kgmiddots)

+rough the experimental study the components at-tached to the combustion are similar to coke which is veryclose to the chemical properties of coke It is assumed thatthe coke surface reaction rate in the dynamic diffusioncontrol combustion model is simultaneously controlled bythe diffusion process and chemical reaction kinetics +ecoke combustion rate is

dmp

dt minusπd

2ppox

aR

a + R (13)

where R is the chemical reaction rate constant RC2exp(minusERTp) kg(kgmiddots)Mp is the current pellet mass of coke kgdp is the current particle diameter of coke m and pox is the

partial pressure of oxidant in vapor phase around the cokeparticles

23 Computational Mesh and Boundary Before calculatingby numerical simulation method a 3D model of biomasspellet rotary burner was established For making the cal-culation of the simulation model faster the burner surfacechamfer and fine structure were properly simplified withoutaffecting the accuracy of the calculation +e fluid model inthe burner was established by Gambit +e tetrahedral meshwas used to divide the body mesh of the fluid model in theburner Figure 2 shows a three-dimensional volume modelof fluid in the burner with a number of nodes of 133078 anda number of grids of 600240 after grid independence

In this paper the boundary conditions are set includingthe inlet velocity boundary the pressure outlet boundaryand the wall boundary and the near-wall region simulationuses the wall function method +e k-ε model is used tosimulate turbulent gas phase flow the scalar conservedmixed fractional probability density function is used tosimulate volatile combustion and the P-1 radiation model isused for simulation research to calculate the radiation ex-change +e kineticdiffusion control reaction rate model isused to simulate the coke combustion +e distributioncharacteristic of the solid phase particle is set to uniform+e Lagrange discrete phase model is used to calculate theinteraction between the particle phase and the gas phase andthe random orbit model is used to track the particle motion+e WSGGM-domain-based model is used to calculate theabsorption coefficient +e inlet boundary is set to the ve-locity inlet and the temperature T is set to 300K +eturbulence intensity is determined by the method of tur-bulence intensity and hydraulic diameter +e outletboundary condition is set to the type of pressure outlet Inthe process of simulating the adiabatic combustion the wallis set to an adiabatic wall surface with no heat flux and massflux It is assumed that the velocity on the wall surface is zero+e proximate and ultimate analyses of the biomass pelletused in the simulation are listed in Table 1

+e productions of the volatile pyrolysis of the biomassfuel are CO H2 H2O and so forth +e pyrolysis equationsof the combustion process are as follows

2C(s) + O2(g) 2CO(g) + 246 446 kJkmol (14)

2CO(s) + O2(g) 2CO2(g) + 567 414 kJkmol (15)

C(s) + CO2(g) 2CO(g) minus 160 140 kJkmol (16)

C(s) + H2O(g) CO(g) + H2(g) minus 118 830 kJkmol (17)

C(s) + 2H2O(g) CO2(g) + 2H2(g) minus 75 114 kJkmol(18)

CO(s) + H2O(g) CO2(g) + H2(g) minus 43 587 kJkmol(19)


For simulating the combustion of the biomass pelletrotary burner it is necessary to determine the independencebetween the grid and the calculated results In the paper fourdifferent density grids of the burner are divided and theresults are shown in Table 2

It can be seen from the table that when the grid is in-creased to 845772 the maximum temperature of the outerburner remains substantially stable When the grid is toodense the simulation time and the computational cost willincrease therefore the second grid is adopted in the analysis

24ModelValidation In order to test the simulation modelthe team established a test bench for the biomass rotaryburner A schematic diagram of the test device for thebiomass rotary burner is shown in Figure 3 It can be seenthat the test instruments include thermocouples flue gasanalyzers fan flow meters and feed screw speed detectiondevices Because this research mainly discusses the com-bustion efficiency of the burner the temperature is the bestevaluation index +erefore temperature measurement isthe key condition of model validation +e measuring in-struments used in the test are specially customized

+e test steps of the main experiments are as follows

(1) At the test site all test devices required for the testplatform are installed

(2) Check that all test devices are complete and whetherthey are consistent with the predetermined size

(3) Check the air tightness of the whole device andcheck whether there is any loose connection

(4) Install various sensors and measuring devices(5) Power on the instrument and ensure that all pipe-

lines are connected(6) Carry out the experiment according to the experi-

ment manual

+e biomass pellet fuel used in the test was fir woodpellet fuel which was compressed into a cylindrical shape bya fuel molding machine with a diameter of 5mm +eprocesses are as follows

(1) Convey the wood pellet fuel by the screw conveyorthe conveying capacity of the conveyor was kept at12 kgh

(2) +e hot air gun was energized and the burner washeated by the hot air for about 10 minutes

(3) When the hot air gun was energized the fan startedto work and then the wind was blasted into thecombustion chamber

(4) When the flame was detected the hot air gun waspowered off and stops working After that the inletvalve was adjusted to change the intake air volume ofthe combustion chamber

Only the measured temperature is reliable due to theerror of measuring instruments caused by hightemperatures

It can be seen from Figures 4 and 5 that the experimentalvalues of the combustion temperature of the biomass rotaryburner are in good agreement with the simulation resultsand the maximum error is 119 because the model isappropriately simplified during the simulation

3 Results and Discussions

In order to make a better comparison with the test resultsthe fir particle fuel has been chosen as the simulated fuel Itsultimate and proximate analysis is shown in Table 1+e feedamount of biomass pellet fuel is set to 12 kgh and the

Table 1+e proximate and ultimate analyses of China fir (air dry)

Proximate analysisMass ratio () Lower heating

value (MJmiddotkgminus1)Moisture Ash Volatile Fixed carbon1192 177 64895 21415 1676

Table 2 Results of the highest temperature of the outlet dependenton different grid densities

Calculation method 1 2 3 4Grid number 19 5064 338 087 62 3300 84 5772Highest temperature (K) 1680 1700 1790 1760

1~5 Thermocouples6 Flue gas analyzer

7 Fan flow meter8 Feed spiral speed detection

1 2 3 4 5

678

Figure 3 Schematic diagram of the thermocouple position in theburner test device

Figure 2 +ree-dimensional mesh model of fluid in the burner


temperature field and CO CO2 and O2 concentrations ofthe biomass pellet burner are numerically simulated underfour conditions of excess air coefficient of 10 14 18 and22

31 Effect of Excess Air Coefficient on TemperatureDistribution Figure 6 shows the longitudinal distribution ofthe combustion temperature of the rotary burner underdifferent excess air coefficients It can be seen from Figure 6that the temperature changes greatly and is mainly con-centrated in the middle region of the rotary burner +ecombustion temperature reaches the maximum in themiddle region of the combustion chamberWith the increaseof excess air ratio the temperature is correspondingly re-duced When the excess air coefficient α is 10 14 18 and22 the maximum temperature of the rotary combustionchamber is 1700K 1600K 1700K and 1600K respectively

Figure 7 shows the temperature distribution along thelongitudinal centerline of the burner under different excessair coefficients It can be seen from Figure 7 that themaximum temperature decreases with the increase of excessair coefficient +is is because as the excess air coefficientstanding for the fuel is larger it will be blown to the tail of theburner before the combustion in the combustion chamber iscompleted +is will lead to an increase in the velocity of theburner outlet which is consistent with the simulationresults

32 Effect of Excess Air Coefficient on CO ConcentrationDistribution +e CO concentration distribution of theburner is shown in Figure 8

It can be seen that CO is mainly concentrated near thefuel inlet where the biomass fuel is richer than other areas sothe CO concentration is also richer and the CO generatingregion decreases when the excess air coefficient increasesWhen the excess air coefficient α is 10 CO is almost dis-tributed throughout the rotary combustion chamber indi-cating that the oxygen supply is insufficient in this areaWhen the excess air coefficient α is 14 the CO concen-tration range decreases with the increase of the oxygencontent and it is limited to the small combustion chamber ofbiomass rotary burner When the excess air coefficient α is22 the CO concentration range is further reduced and therange of the maximum CO concentration is greatly reduced

Figure 9 shows the distribution of the CO concentrationalong the axial centerline of the burner under four operatingconditions

It can be seen from the curve in Figure 9 that the COconcentration under the four working conditions shows anapproximate parabolic distribution It increases rapidly firstand then decreases slowly indicating that the biomass fuel isenough when it enters the combustion chamber and anincomplete combustion reaction occurs and then the COconcentration increases With the increase of O2 CO un-dergoes further oxidation reaction to form CO2 whichcauses the CO concentration to decrease while the CO2

T (K)

1900175516091464131811731027882736591445300

(a)

T (K)

1900175516091464131811731027882736591445300

(b)

Figure 4 Temperature distribution of the gas phase in the burner (a) Longitudinal distribution (α12) (b) Horizontal distribution(α12) (Y 0364m)

1 2 3 4 5700800900

100011001200130014001500160017001800

Com

busti

on te

mpe

ratu

re o

f bur

ner

Thermocouple position

Experimental valueSimulation value

Figure 5 Comparison of simulation and experimental values ofthe burnersrsquo combustion temperature


concentration is corresponding to increase It can be seenthat the CO concentration in the burner gradually decreaseswith the increase of the excess air coefficient

33 Effect of Excess Air Coefficient on CO2 ConcentrationDistribution +e CO2 concentration distribution of therotary burner is shown in Figure 10 +e CO2 concentrationis mainly concentrated in the middle region of the burner+e CO2 generating region decreases with the increase of theexcess air coefficient When the excess air coefficient α is 10CO2 is almost distributed throughout the rotary combustionchamber indicating that biomass fuel is almost combustedcompletely When the excess air coefficient α is 14 the areaof the CO2 concentration range decreases compared with theexcess air coefficient 10 When the excess air coefficient α is18 the CO2 concentration range decreases with the increaseof the oxygen content and it is limited to the longitudinalregion of the biomass rotary burner When the excess aircoefficient α is 24 the CO2 concentration range is further

T (K)

1700

1573

1445

1318

1191

1064

936

809

682

555

427

300

(a)

T (K)

1600150014001300120011001000900800700600500400300

(b)

T (K)1700

1573

1445

1318

1191

1064

936

809

682

555

427

300

(c)

T (K)1600

1482

1364

1245

1127

1009

891

773

655

536

418

300

(d)

Figure 6 Longitudinal distribution of the combustion temperature of the rotary burner under different excess air coefficients (a) α 10 (b)α 14 (c) α 18 (d) α 22

00 01 02 03 04 05

200

400

600

800

1000

1200

1400

1600

Tem

pera

ture

(K)

Axial position (m)

a = 10a = 14

a = 18a = 22

Figure 7 Temperature distribution along the longitudinal cen-terline of the burner under different excess air coefficients


reduced and the range of the maximum CO2 concentrationis also greatly reduced

Figure 11 shows the distribution of CO2 concentrationalong the longitudinal centerline of the burner under fouroperating conditions It can be seen from the curve inFigure 11 that the CO2 concentration under the four op-erating conditions gradually increases with the reaction ofcombustion and then it remains stable As excess air co-efficient increases the CO2 concentration in the burner isgradually reduced

34 Effect of Excess Air Coefficient on O2 ConcentrationDistribution +e O2 concentration distribution of theburner is shown in Figure 12 As shown in Figure 12 O2 ismainly concentrated near the airflow inlet at a lower excessair coefficient When the excess air coefficient increases thebiomass fuel will burn faster and the O2 region will increasewith the increase of excess air coefficient Figure 13 is adistribution curve of the O2 concentration along the

CO fraction

016

015

013

012

011

010

008

007

006

005

003

002

(a)

CO fraction

014013012010009008007006005004003002001

(b)

CO fraction

012013

011010009008007006005004003002001

(c)

CO fraction

010

011

009

008

007

006

005

004

003

002

001

(d)

Figure 8 Longitudinal distribution of the CO concentration of the rotary burner under different excess air coefficients (a) α 10 (b)α 14 (c) α 18 (d) α 22

00 01 02 03 04 05ndash001

000

001

002

003

004

005

006

007

008

CO m

ass f

ract

ion

()

Axial position (m)

a = 10a = 14

a = 18a = 22

Figure 9 CO concentration distribution along the longitudinalcenterline of the burner under different excess air coefficients


longitudinal centerline of the burner under four operatingconditions As shown in Figure 13 the distribution of O2concentration gradually increases with the increase of excessair coefficient under the four operating conditions At alower excess air coefficient oxygen is concentrated mainlynear the airflow inlet +e middle and lower regions of theburner form a relatively low oxygen atmosphere

35 Current and FutureDevelopments It is a very importantresearch topic to improve combustion efficiency [38ndash40] andreduce pollutant emissions [41ndash46] by changing the shapeand structure size of the burners As for the swirl burner thelatter research should be based on the existing model re-search and carry out relevant simulation and experimentalresearch Relevant model modification and parameter sen-sitivity should be explored +e internal distribution andmain distribution trend of the flow field are obtained +ecomputational fluid dynamics software can be applied to

CO2 fraction

022

024

020

018

016

014

012

010

008

006

004

002

(a)

CO2 fraction

022024026

020018016014012010008006004002

(b)

CO2 fraction

022

024

020

018

016

014

012

010

008

006

004

002

(c)

CO2 fraction

022

024

026

019

017

015

013

011

009

006

004

002

(d)

Figure 10 Longitudinal distribution of the CO2 concentration of the rotary burner under different excess air coefficients (a) α 10 (b)α 14 (c) α 18 (d) α 22

00 01 02 03 04 05

000

005

010

015

020

025

030

CO2 m

ass f

ract

ion

()

Axial position (m)

a = 10a = 14

a = 18a = 22

Figure 11 CO2 concentration distribution along the longitudinalcenterline of the burner under different excess air coefficients


simulate the combustion characteristics of the biomassrotary burner in steady condition +e structure of the swirlburner will be more reasonable and it can use fuel efficiently

4 Conclusions

+rough the simulation and experimental research on thecombustion characteristics of the biomass rotary burner theconclusions are obtained as follows

(1) +e area where the temperature changes greatly ismainly concentrated in the middle part of the rotarycombustor the combustion temperature reaches themaximum in this region and the temperature issmaller in other regions According to the simulationresults the temperature of the burner decreases withthe increase of the excess air coefficient

(2) CO is mainly concentrated near the fuel inlet be-cause the excess air coefficient is bigger than other

O2 fraction022

020

018

016

014

012

010

008

006

004

002

(a)

O2 fraction022

020

018

016

014

012

010

008

006

004

002

(b)

O2 fraction022

020

018

016

014

012

010

008

006

004

002

(c)

O2 fraction022

020

018

017

015

013

011

009

007

006

004

002

(d)

Figure 12 Longitudinal distribution of the O2 concentration of the rotary burner under different excess air coefficients (a) α 10 (b)α 14 (c) α 18 (d) α 22

00 01 02 03 04 05ndash002

000002004006008010012014016018020022024

O2 m

ass f

ract

ion

()

Axial position (m)

a = 10a = 14

a = 18a = 22

Figure 13 O2 concentration distribution along the longitudinalcenterline of the burner under different excess air coefficients


areas so CO is richer than other regions Accordingto the simulation results the region of CO decreaseswith the increase of the excess air coefficient CO2 ismainly concentrated in the middle region of theburner and the CO2 generating region decreases withthe increase of excess air coefficient O2 is mainlyconcentrated near the airflow inlet at lower excess aircoefficient and the biomass fuel burns faster and O2region also increases with the increase of excess aircoefficient

(3) +e experimental values of the combustion tem-perature of the biomass rotary burner are in goodagreement with the simulation results It is becausethe model is appropriately simplified in thesimulation

Nomenclature

ρ +e fluid density kgm3

cp +e specific heat of fluid J(kgmiddotK)U +e velocity field msT +e temperature Kh +e thermal conductivity W(mmiddotK)p +e fluid pressure Paμ +e dynamic viscosity PamiddotsSu SvSw

+e generalized source terms for the momentumconservation equation

l +e turbulent kinetic energy Jμt +e turbulent viscosity kg(mmiddots)Gk +e generation term of the turbulent kinetic JSk +e source term of turbulent kinetic energy Jσk +e Prandtl numberV +e average velocity vector msSm +e source term caused by chemical reaction kg

(m3middots)a +e absorption coefficientσs +e scattering coefficientG +e incident radiation Wm2

C +e linear anisotropic phase function coefficientSG +e source term of user-defined radiation Wm2

Data Availability

+e data in this paper are provided by the manufacturercompany which involves product matching and technicalparameters of the company

Conflicts of Interest

+e authors declare that they have no conflicts of interestregarding the publication of this paper

Acknowledgments

+is work was supported by the China Post-doctoral ScienceFoundation (2016M592455) Hunan Provincial EducationDepartmentrsquos Scientific Research Project (17B278) HunanProvincial Universityrsquos Science and Technology InnovationTeam Support Plan (2014207) and Central South University

of Forestry and Technologyrsquos School-level Youth ScienceFoundation Project (QJ2017006B)

References

[1] D Zhao and L Li ldquoEffect of choked outlet on transient energygrowth analysis of a thermoacoustic systemrdquo Applied Energyvol 160 pp 502ndash510 2015

[2] J Chen W Xu H Zuo et al ldquoSystem development andenvironmental performance analysis of a solar-driven su-percritical water gasification pilot plant for hydrogen pro-duction using life cycle assessment approachrdquo EnergyConversion and Management vol 184 pp 60ndash73 2019

[3] H Zuo G Liu E Jiaqiang et al ldquoCatastrophic analysis on thestability of a large dish solar thermal power generation systemwith wind-induced vibrationrdquo Solar Energy vol 183pp 40ndash49 2019

[4] X Zhao G Wu E Jiaqiang et al ldquoA review of studies usinggraphenes in energy conversion energy storage and heattransfer developmentrdquo Energy Conversion and Managementvol 184 pp 581ndash599 2019

[5] E Jiaqiang G Liu Z Zhang et al ldquoEffect analysis on coldstarting performance enhancement of a diesel engine fueledwith biodiesel fuel based on an improved thermodynamicmodelrdquo Applied Energy vol 243 pp 321ndash335 2019

[6] E Jiaqiang J Gao Q Peng Z Zhang and P M Hieu ldquoEffectanalysis on pressure drop of the continuous regeneration-diesel particulate filter based on NO2 assisted regenerationrdquoApplied gtermal Engineering vol 100 pp 356ndash366 2016

[7] E Jiaqiang Z Zhang J Chen et al ldquoPerformance andemission evaluation of a marine diesel engine fueled by waterbiodiesel-diesel emulsion blends with a fuel additive of acerium oxide nanoparticlerdquo Energy Conversion and Man-agement vol 169 pp 194ndash205 2018

[8] E Jiaqiang X Zhao L Xie et al ldquoPerformance enhancementof microwave assisted regeneration in a wall-flow dieselparticulate filter based on field synergy theoryrdquo Energyvol 169 pp 719ndash729 2019

[9] Z Zhang E Jiaqiang Y Deng et al ldquoEffects of fatty acidmethylesters proportion on combustion and emission characteristicsof a biodiesel fueled marine diesel enginerdquo Energy Conversionand Management vol 159 pp 244ndash253 2018

[10] Z Zhang E Jiaqiang J Chen et al ldquoEffects of low-level wateraddition on spray combustion and emission characteristics ofa medium speed diesel engine fueled with biodiesel fuelrdquo Fuelvol 239 pp 245ndash262 2019

[11] D Zhao E Gutmark and P de Goey ldquoA review of cavity-based trapped vortex ultra-compact high-g inter-turbinecombustorsrdquo Progress in Energy and Combustion Sciencevol 66 pp 42ndash82 2018

[12] D Zhao C Ji X Li and S Li ldquoMitigation of premixed flame-sustained thermoacoustic oscillations using an electricalheaterrdquo International Journal of Heat and Mass Transfervol 86 pp 309ndash318 2015

[13] J Chen Y Fan E Jiaqiang et al ldquoEffects analysis on thegasification kinetic characteristics of food waste in super-critical waterrdquo Fuel vol 241 pp 94ndash104 2019

[14] E Jiaqiang G Liu T Liu et al ldquoHarmonic response analysisof a large dish solar thermal power generation system withwind-induced vibrationrdquo Solar Energy vol 181 pp 116ndash1292019

[15] Y Li W Tang Y Chen J Liu and C-f F Lee ldquoPotential ofacetone-butanol-ethanol (ABE) as a biofuelrdquo Fuel vol 242pp 673ndash686 2019


[16] H Khodaei G H Yeoh F Guzzomi and J Porteiro ldquoA CFD-based comparative analysis of drying in various single bio-mass particlesrdquo Applied gtermal Engineering vol 128pp 1062ndash1073 2018

[17] M Buchmayr J Gruber M Hargassner and C HochenauerldquoA computationally inexpensive CFD approach for small-scale biomass burners equipped with enhanced air stagingrdquoEnergy Conversion and Management vol 115 pp 32ndash422016

[18] M Farokhi M Birouk and F Tabet ldquoA computational studyof a small-scale biomass burner the influence of chemistryturbulence and combustion sub-modelsrdquo Energy Conversionand Management vol 143 pp 203ndash217 2017

[19] J Fagerstrom E Steinvall D Bostrom and C Boman ldquoAlkalitransformation during single pellet combustion of soft woodand wheat strawrdquo Fuel Processing Technology vol 143pp 204ndash212 2016

[20] M M Roy A Dutta and K Corscadden ldquoAn experimentalstudy of combustion and emissions of biomass pellets in aprototype pellet furnacerdquo Applied Energy vol 108 pp 298ndash307 2013

[21] E D Vicente and C A Alves ldquoAn overview of particulateemissions from residential biomass combustionrdquo Atmo-spheric Research vol 199 pp 159ndash185 2018

[22] J E Henderson O Joshi R Parajuli and W G Hubbard ldquoAregional assessment of wood resource sustainability andpotential economic impact of the wood pellet market in theUS Southrdquo Biomass and Bioenergy vol 105 pp 421ndash4272017

[23] L J R Nunes J C O Matias and J P S Catalatildeo ldquoA reviewon torrefied biomass pellets as a sustainable alternative to coalin power generationrdquo Renewable and Sustainable EnergyReviews vol 40 pp 153ndash160 2014

[24] M Mobini J-C Meyer F Trippe T Sowlati M Frohlingand F Schultmann ldquoAssessing the integration of torrefactioninto wood pellet productionrdquo Journal of Cleaner Productionvol 78 pp 216ndash225 2014

[25] S Proskurina E Alakangas J Heinimo M Mikkila andE Vakkilainen ldquoA survey analysis of the wood pellet industryin Finland future perspectivesrdquo Energy vol 118 pp 692ndash7042017

[26] B Coelho A Oliveira P Schwarzbozl and A MendesldquoBiomass and central receiver system (CRS) hybridizationintegration of syngasbiogas on the atmospheric air volu-metric CRS heat recovery steam generator duct burnerrdquoRenewable Energy vol 75 pp 665ndash674 2015

[27] M S Roni S Chowdhury S Mamun M MarufuzzamanW Lein and S Johnson ldquoBiomass co-firing technology withpolicies challenges and opportunities a global reviewrdquo Re-newable and Sustainable Energy Reviews vol 78 pp 1089ndash1101 2017

[28] E Toklu ldquoBiomass energy potential and utilization in Tur-keyrdquo Renewable Energy vol 107 pp 235ndash244 2017

[29] S Proskurina J Heinimo F Schipfer and E VakkilainenldquoBiomass for industrial applications the role of torrefactionrdquoRenewable Energy vol 111 pp 265ndash274 2017

[30] M M O Carvalho M Cardoso and E K VakkilainenldquoBiomass gasification for natural gas substitution in iron orepelletizing plantsrdquo Renewable Energy vol 81 pp 566ndash5772015

[31] R Garcıa C Pizarro A G Lavın and J L Bueno ldquoBiomasssources for thermal conversion Techno-economical over-viewrdquo Fuel vol 195 pp 182ndash189 2017

[32] C M S D Silva A D C O Carneiro B R Vital et alldquoBiomass torrefaction for energy purposes-definitions and anoverview of challenges and opportunities in Brazilrdquo Renew-able and Sustainable Energy Reviews vol 82 pp 2426ndash24322018

[33] Y Xu Y Wang Y Chen et al ldquoCharacterization of fine andcarbonaceous particles emissions from pelletized biomass-coal blends combustion implications on residential cropresidue utilization in Chinardquo Atmospheric Environmentvol 141 pp 312ndash319 2016

[34] J Ahn and J H Jang ldquoCombustion characteristics of a 16 stepgrate-firing wood pellet boilerrdquo Renewable Energy vol 129pp 678ndash685 2018

[35] C Ndibe J Maier and G Scheffknecht ldquoCombustioncofiring and emissions characteristics of torrefied biomass in adrop tube reactorrdquo Biomass and Bioenergy vol 79 pp 105ndash115 2015

[36] A Kraszkiewicz A Przywara M Kachel-Jakubowska andE Lorencowicz ldquoCombustion of plant biomass pellets on thegrate of a low power boilerrdquo Agriculture and AgriculturalScience Procedia vol 7 pp 131ndash138 2015

[37] L Chai and C M Saffron ldquoComparing pelletization andtorrefaction depots optimization of depot capacity andbiomass moisture to determine the minimum productioncostrdquo Applied Energy vol 163 pp 387ndash395 2016

[38] H Chu L Xiang X Nie Y Ya M Gu and E JiaqiangldquoLaminar burning velocity and pollutant emissions of thegasoline components and its surrogate fuels a reviewrdquo Fuelvol 269 p 117451 2020

[39] G Wu D Wu Y Li and L Meng ldquoEffect of acetone-n-butanol-ethanol (ABE) as an oxygenate on combustionperformance and emission characteristics of a spark ignitionenginerdquo Journal of Chemistry vol 2020 Article ID 746865111 pages 2020

[40] Q Zuo Y Xie Q Guan et al ldquoPerformance enhancement of agasoline dual-carrier catalytic converter of the gasoline enginein the reaction equilibrium processrdquo Energy Conversion andManagement vol 204 Article ID 112325 2020

[41] Q Zuo Y Xie E Jiaqiang et al ldquoEffect of different exhaustparameters on NO conversion efficiency enhancement of adual-carrier catalytic converter in the gasoline enginerdquo En-ergy vol 191 Article ID 116521 2020

[42] Q Zuo Y TangW Chen J Zhang L Shi and Y Xie ldquoEffectsof exhaust parameters on gasoline soot regeneration per-formance of a catalytic gasoline particulate filter in equilib-rium staterdquo Fuel vol 265 Article ID 117001 2020

[43] E Jiaqiang M Zhao Q Zuo et al ldquoEffects analysis on dieselsoot continuous regeneration performance of a rotary mi-crowave-assisted regeneration diesel particulate filterrdquo Fuelvol 260 p 116353 2020

[44] K Wei Y Yang H Zuo and D Zhong ldquoA review on icedetection technology and ice elimination technology for windturbinerdquo Wind Energy vol 23 no 3 pp 433ndash457 2020

[45] B Zhang H Zuo Z Huang J Tan and Q Zuo ldquoEndpointforecast of different diesel-biodiesel soot filtration process indiesel particulate filters considering ash depositionrdquo Fuelvol 271 Article ID 117678 2020

[46] G Liao E Jiaqiang F Zhang J Chen and E Leng ldquoLengAdvanced exergy analysis for optimized ORC-based layout torecover waste heat of flue gas in coal-fired plantsrdquo AppliedEnergy vol 266 Article ID 114891 2020


and combustion models as well as chemistry schemes on thecombustion of an 8ndash11 kW small lab-scale biomass furnaceFagerstrom et al [19] used a macro-TGA reactor to de-termine the release of ash forming elements during devo-latilization and char combustion of single pellets Soft woodand wheat straw were combusted at two temperatures(700degC and 1000degC) and the residual ashes were collectedand analyzed for morphology elemental and phase com-position Roy et al [20] presented combustion and emissionresults obtained using a prototype pellet furnace with7ndash32 kW capacity (designed for burning high ash contentpellet fuels) for four biomass pellets one grass pellet andthree wood pellets Fuel property gas emissions and furnaceefficiency are compared Vicente and Alves [21] presented anextensive tabulation of particulate matter emission factorsobtained worldwide and critically evaluated Hendersonet al [22] explained how local economies can benefit fromwood pellet manufacturing by expressing the economicmultiplier effect of wood pellet plant operations in terms ofemployment wages and salaries and value-added in each ofthe 13 states in the US South Nunes et al [23] studiedseveral studies on the torrefaction of biomass for heat andpower applications in the literature which need to bereviewed and analyzed for further actions in the field be-cause significant gaps remain in the understanding of thebiomass torrefaction process which necessitate furtherstudy mainly concerning the characterization of the tor-refaction chemical reactions investigation of equipmentperformance and design and elucidation of supply chainimpacts Mobini et al [24] used a dynamic simulationmodeling approach to assess the integration of torrefactioninto the wood pellet production and distribution supplychain +e developed a model that combined discrete eventand discrete rate simulation approaches and allowed con-sidering uncertainties interdependencies and resourceconstraints along the supply chain which were usuallysimplified or ignored in static and deterministic models

Proskurina et al [25] presented an overview of the currentstatus of the Finnish wood pellet business and discussed themain opportunities and challenges facing the future devel-opment of the industry Coelho et al [26] studied several basecase power plants and hybrid biomassCSP options woodgasification refuse-derived fuel pellets biogas from awastewater anaerobic digester and biogas from a landfill andnatural gas Roni et al [27] investigated the existing cofiringplants with technologies and the availability of biomass re-sources in different countries of the world Finally this papersummarized the major global biomass cofiring initiatives andthe prospects of biomass cofiring in securing renewable en-ergy targets Toklu [28] showed that there is an importantbiomass energy potential for climate change mitigation andenergy sustainability in Turkey Proskurina et al [29] eval-uated the potential of torrefied biomass in different industriesboth power and nonpower generation industries and con-sidered the impact of such use on the international biomassmarket Carvalho et al [30] compared different technologiessuch as CFB air and oxygen gasification dual fluidized bed(DFB) steam gasification and bio-synthetic natural gas (bio-SNG) production focusing on the use of the product gas in an

iron ore pelletizing process located in the Southeast of BrazilGarcıa et al [31] analyzed thirteen alternative raw biomasssamples and compared themwith briquette wood pellets andcharcoal and considered the data of their proximate ultimateand calorimetric analysis and physical properties Silva et al[32] evaluated the application potential of torrefaction in thesolid fuelrsquos production from lignocellulosic biomasses inBrazil Xu et al [33] evaluated the reductions in PM25organic carbon (OC) and elemental carbon (EC) emissions bycomparing emission factors (EFs) among 19 combinations ofbiofuelresidential stove types measured using a dilutionsampling system Ahn and Jang [34] manufactured and testeda prototype of a 230 kW class wood pellet boiler employing afour-step grate Ndibe et al [35] investigated cofiring char-acteristics of torrefied biomass fuels at 50 thermal shareswith coals and 100 combustion cases Kraszkiewicz et al[36] analyzed the results of the CO NO and SO2 emissionfrom burning pellets of oil cake rape straw and birch sawdustin the low-temperature water boiler of the top combustionChai and Saffron [37] optimized the biomass upgrading depotcapacity and biomass feedstock moisture to obtain theminimum production cost at the depot gate to producewoody biofuels

In this paper a biomass pellet rotary burner with the spiralcleaning and slagging device was chosen as the research objectin order to study the influence of excess air coefficient on thecombustion efficiency According to the combustion char-acteristics of the biomass (wood pellet) a high-efficiencydouble-layer combustion drum device has been designed toachieve a better flow distribution in this study +e flowvelocity distribution characteristics in the burner have animportant effect on the combustion efficiency of the biomass(wood pellet)+e flow field distribution and combustion fielddistribution of the new biomass rotary burner are studiedwhich can reduce the test workload and shorten the designcycle +e CFD software was applied to simulate the com-bustion characteristics of biomass rotary burner in steadycondition and the effects of the excess air ratio on thetemperature field and component concentration field in thebiomass rotary burner were analyzed

2 Numerical Model

21 Physical Model of Biomass Rotary Burner In order toimprove the thermal efficiency of the biomass rotary burner arotary combustion chamber has been used in the biomassrotary burner for reducing the pollutants A screw feed device isused to control the appropriate amount of biomass (woodpellet) +e schematic diagram of the biomass rotary burner isshown in Figure 1 which is mainly constituted by the spiralfeeding mechanism rotary combustion chamber small com-bustion chamber connecting flange and other components

When the burner is working the biomass pellets are fedfrom the feed spiral tube into the rotary combustionchamber +e air is blown into the rotary combustionchamber through the secondary air pores to make thebiomass particles burn completely +e combustion char-acteristics of the burner in the steady state are studied in thepaper





div(ρU) 0 (1)



zx+ Su


zy+ Sv


zz+ Sw

⎧⎪⎪⎪⎪⎪⎪⎪⎪⎪⎪⎪⎪⎨

⎪⎪⎪⎪⎪⎪⎪⎪⎪⎪⎪⎪⎩

(2)



div(ρUT) divh

cp

gradT1113888 1113889 + ST (3)



z ρkui( 1113857

zxi

z

zxj

μ +μt

σk

1113888 1113889zk

zxj

1113890 1113891 + Gk minus ρε + Sk (4)


z ρεui( 1113857

zxi

z

zxj

μ +μt

σε1113888 1113889

zεzxj

1113890 1113891 +εk


(5)



f Zi minus Ziox



z


μt

σt

nablaf1113888 1113889 + Sm

z


μt

σt


minus Cdρεk

middot fprime2

(7)


1 2 3 4

567







qr 1


nablaG (8)






SG (10)






mv(t)


1113946t

0α1R1 + α2R2( 1113857


0R1 + R2( 1113857dt1113888 1113889dt

(12)



dmp

dt minusπd

2ppox

aR

a + R (13)






2C(s) + O2(g) 2CO(g) + 246 446 kJkmol (14)

2CO(s) + O2(g) 2CO2(g) + 567 414 kJkmol (15)















ment manual

















1 2 3 4 5

678











T (K)

1900175516091464131811731027882736591445300

(a)

T (K)

1900175516091464131811731027882736591445300

(b)


1 2 3 4 5700800900

100011001200130014001500160017001800

Com

busti

on te

mpe

ratu

re o

f bur

ner







T (K)

1700

1573

1445

1318

1191

1064

936

809

682

555

427

300

(a)

T (K)

1600150014001300120011001000900800700600500400300

(b)

T (K)1700

1573

1445

1318

1191

1064

936

809

682

555

427

300

(c)

T (K)1600

1482

1364

1245

1127

1009

891

773

655

536

418

300

(d)


00 01 02 03 04 05

200

400

600

800

1000

1200

1400

1600

Tem

pera

ture

(K)

Axial position (m)

a = 10a = 14

a = 18a = 22






CO fraction

016

015

013

012

011

010

008

007

006

005

003

002

(a)

CO fraction

014013012010009008007006005004003002001

(b)

CO fraction

012013

011010009008007006005004003002001

(c)

CO fraction

010

011

009

008

007

006

005

004

003

002

001

(d)


00 01 02 03 04 05ndash001

000

001

002

003

004

005

006

007

008

CO m

ass f

ract

ion

()

Axial position (m)

a = 10a = 14

a = 18a = 22





CO2 fraction

022

024

020

018

016

014

012

010

008

006

004

002

(a)

CO2 fraction

022024026

020018016014012010008006004002

(b)

CO2 fraction

022

024

020

018

016

014

012

010

008

006

004

002

(c)

CO2 fraction

022

024

026

019

017

015

013

011

009

006

004

002

(d)


00 01 02 03 04 05

000

005

010

015

020

025

030

CO2 m

ass f

ract

ion

()

Axial position (m)

a = 10a = 14

a = 18a = 22




4 Conclusions




O2 fraction022

020

018

016

014

012

010

008

006

004

002

(a)

O2 fraction022

020

018

016

014

012

010

008

006

004

002

(b)

O2 fraction022

020

018

016

014

012

010

008

006

004

002

(c)

O2 fraction022

020

018

017

015

013

011

009

007

006

004

002

(d)


00 01 02 03 04 05ndash002

000002004006008010012014016018020022024

O2 m

ass f

ract

ion

()

Axial position (m)

a = 10a = 14

a = 18a = 22





Nomenclature







Data Availability




Acknowledgments



References




















































div(ρU) 0 (1)



zx+ Su


zy+ Sv


zz+ Sw

⎧⎪⎪⎪⎪⎪⎪⎪⎪⎪⎪⎪⎪⎨

⎪⎪⎪⎪⎪⎪⎪⎪⎪⎪⎪⎪⎩

(2)



div(ρUT) divh

cp

gradT1113888 1113889 + ST (3)



z ρkui( 1113857

zxi

z

zxj

μ +μt

σk

1113888 1113889zk

zxj

1113890 1113891 + Gk minus ρε + Sk (4)


z ρεui( 1113857

zxi

z

zxj

μ +μt

σε1113888 1113889

zεzxj

1113890 1113891 +εk


(5)



f Zi minus Ziox



z


μt

σt

nablaf1113888 1113889 + Sm

z


μt

σt


minus Cdρεk

middot fprime2

(7)


1 2 3 4

567







qr 1


nablaG (8)






SG (10)






mv(t)


1113946t

0α1R1 + α2R2( 1113857


0R1 + R2( 1113857dt1113888 1113889dt

(12)



dmp

dt minusπd

2ppox

aR

a + R (13)






2C(s) + O2(g) 2CO(g) + 246 446 kJkmol (14)

2CO(s) + O2(g) 2CO2(g) + 567 414 kJkmol (15)















ment manual

















1 2 3 4 5

678











T (K)

1900175516091464131811731027882736591445300

(a)

T (K)

1900175516091464131811731027882736591445300

(b)


1 2 3 4 5700800900

100011001200130014001500160017001800

Com

busti

on te

mpe

ratu

re o

f bur

ner







T (K)

1700

1573

1445

1318

1191

1064

936

809

682

555

427

300

(a)

T (K)

1600150014001300120011001000900800700600500400300

(b)

T (K)1700

1573

1445

1318

1191

1064

936

809

682

555

427

300

(c)

T (K)1600

1482

1364

1245

1127

1009

891

773

655

536

418

300

(d)


00 01 02 03 04 05

200

400

600

800

1000

1200

1400

1600

Tem

pera

ture

(K)

Axial position (m)

a = 10a = 14

a = 18a = 22






CO fraction

016

015

013

012

011

010

008

007

006

005

003

002

(a)

CO fraction

014013012010009008007006005004003002001

(b)

CO fraction

012013

011010009008007006005004003002001

(c)

CO fraction

010

011

009

008

007

006

005

004

003

002

001

(d)


00 01 02 03 04 05ndash001

000

001

002

003

004

005

006

007

008

CO m

ass f

ract

ion

()

Axial position (m)

a = 10a = 14

a = 18a = 22





CO2 fraction

022

024

020

018

016

014

012

010

008

006

004

002

(a)

CO2 fraction

022024026

020018016014012010008006004002

(b)

CO2 fraction

022

024

020

018

016

014

012

010

008

006

004

002

(c)

CO2 fraction

022

024

026

019

017

015

013

011

009

006

004

002

(d)


00 01 02 03 04 05

000

005

010

015

020

025

030

CO2 m

ass f

ract

ion

()

Axial position (m)

a = 10a = 14

a = 18a = 22




4 Conclusions




O2 fraction022

020

018

016

014

012

010

008

006

004

002

(a)

O2 fraction022

020

018

016

014

012

010

008

006

004

002

(b)

O2 fraction022

020

018

016

014

012

010

008

006

004

002

(c)

O2 fraction022

020

018

017

015

013

011

009

007

006

004

002

(d)


00 01 02 03 04 05ndash002

000002004006008010012014016018020022024

O2 m

ass f

ract

ion

()

Axial position (m)

a = 10a = 14

a = 18a = 22





Nomenclature







Data Availability




Acknowledgments



References



















































qr 1


nablaG (8)






SG (10)






mv(t)


1113946t

0α1R1 + α2R2( 1113857


0R1 + R2( 1113857dt1113888 1113889dt

(12)



dmp

dt minusπd

2ppox

aR

a + R (13)






2C(s) + O2(g) 2CO(g) + 246 446 kJkmol (14)

2CO(s) + O2(g) 2CO2(g) + 567 414 kJkmol (15)















ment manual

















1 2 3 4 5

678











T (K)

1900175516091464131811731027882736591445300

(a)

T (K)

1900175516091464131811731027882736591445300

(b)


1 2 3 4 5700800900

100011001200130014001500160017001800

Com

busti

on te

mpe

ratu

re o

f bur

ner







T (K)

1700

1573

1445

1318

1191

1064

936

809

682

555

427

300

(a)

T (K)

1600150014001300120011001000900800700600500400300

(b)

T (K)1700

1573

1445

1318

1191

1064

936

809

682

555

427

300

(c)

T (K)1600

1482

1364

1245

1127

1009

891

773

655

536

418

300

(d)


00 01 02 03 04 05

200

400

600

800

1000

1200

1400

1600

Tem

pera

ture

(K)

Axial position (m)

a = 10a = 14

a = 18a = 22






CO fraction

016

015

013

012

011

010

008

007

006

005

003

002

(a)

CO fraction

014013012010009008007006005004003002001

(b)

CO fraction

012013

011010009008007006005004003002001

(c)

CO fraction

010

011

009

008

007

006

005

004

003

002

001

(d)


00 01 02 03 04 05ndash001

000

001

002

003

004

005

006

007

008

CO m

ass f

ract

ion

()

Axial position (m)

a = 10a = 14

a = 18a = 22





CO2 fraction

022

024

020

018

016

014

012

010

008

006

004

002

(a)

CO2 fraction

022024026

020018016014012010008006004002

(b)

CO2 fraction

022

024

020

018

016

014

012

010

008

006

004

002

(c)

CO2 fraction

022

024

026

019

017

015

013

011

009

006

004

002

(d)


00 01 02 03 04 05

000

005

010

015

020

025

030

CO2 m

ass f

ract

ion

()

Axial position (m)

a = 10a = 14

a = 18a = 22




4 Conclusions




O2 fraction022

020

018

016

014

012

010

008

006

004

002

(a)

O2 fraction022

020

018

016

014

012

010

008

006

004

002

(b)

O2 fraction022

020

018

016

014

012

010

008

006

004

002

(c)

O2 fraction022

020

018

017

015

013

011

009

007

006

004

002

(d)


00 01 02 03 04 05ndash002

000002004006008010012014016018020022024

O2 m

ass f

ract

ion

()

Axial position (m)

a = 10a = 14

a = 18a = 22





Nomenclature







Data Availability




Acknowledgments



References


























































ment manual

















1 2 3 4 5

678











T (K)

1900175516091464131811731027882736591445300

(a)

T (K)

1900175516091464131811731027882736591445300

(b)


1 2 3 4 5700800900

100011001200130014001500160017001800

Com

busti

on te

mpe

ratu

re o

f bur

ner







T (K)

1700

1573

1445

1318

1191

1064

936

809

682

555

427

300

(a)

T (K)

1600150014001300120011001000900800700600500400300

(b)

T (K)1700

1573

1445

1318

1191

1064

936

809

682

555

427

300

(c)

T (K)1600

1482

1364

1245

1127

1009

891

773

655

536

418

300

(d)


00 01 02 03 04 05

200

400

600

800

1000

1200

1400

1600

Tem

pera

ture

(K)

Axial position (m)

a = 10a = 14

a = 18a = 22






CO fraction

016

015

013

012

011

010

008

007

006

005

003

002

(a)

CO fraction

014013012010009008007006005004003002001

(b)

CO fraction

012013

011010009008007006005004003002001

(c)

CO fraction

010

011

009

008

007

006

005

004

003

002

001

(d)


00 01 02 03 04 05ndash001

000

001

002

003

004

005

006

007

008

CO m

ass f

ract

ion

()

Axial position (m)

a = 10a = 14

a = 18a = 22





CO2 fraction

022

024

020

018

016

014

012

010

008

006

004

002

(a)

CO2 fraction

022024026

020018016014012010008006004002

(b)

CO2 fraction

022

024

020

018

016

014

012

010

008

006

004

002

(c)

CO2 fraction

022

024

026

019

017

015

013

011

009

006

004

002

(d)


00 01 02 03 04 05

000

005

010

015

020

025

030

CO2 m

ass f

ract

ion

()

Axial position (m)

a = 10a = 14

a = 18a = 22




4 Conclusions




O2 fraction022

020

018

016

014

012

010

008

006

004

002

(a)

O2 fraction022

020

018

016

014

012

010

008

006

004

002

(b)

O2 fraction022

020

018

016

014

012

010

008

006

004

002

(c)

O2 fraction022

020

018

017

015

013

011

009

007

006

004

002

(d)


00 01 02 03 04 05ndash002

000002004006008010012014016018020022024

O2 m

ass f

ract

ion

()

Axial position (m)

a = 10a = 14

a = 18a = 22





Nomenclature







Data Availability




Acknowledgments



References
























































T (K)

1900175516091464131811731027882736591445300

(a)

T (K)

1900175516091464131811731027882736591445300

(b)


1 2 3 4 5700800900

100011001200130014001500160017001800

Com

busti

on te

mpe

ratu

re o

f bur

ner







T (K)

1700

1573

1445

1318

1191

1064

936

809

682

555

427

300

(a)

T (K)

1600150014001300120011001000900800700600500400300

(b)

T (K)1700

1573

1445

1318

1191

1064

936

809

682

555

427

300

(c)

T (K)1600

1482

1364

1245

1127

1009

891

773

655

536

418

300

(d)


00 01 02 03 04 05

200

400

600

800

1000

1200

1400

1600

Tem

pera

ture

(K)

Axial position (m)

a = 10a = 14

a = 18a = 22






CO fraction

016

015

013

012

011

010

008

007

006

005

003

002

(a)

CO fraction

014013012010009008007006005004003002001

(b)

CO fraction

012013

011010009008007006005004003002001

(c)

CO fraction

010

011

009

008

007

006

005

004

003

002

001

(d)


00 01 02 03 04 05ndash001

000

001

002

003

004

005

006

007

008

CO m

ass f

ract

ion

()

Axial position (m)

a = 10a = 14

a = 18a = 22





CO2 fraction

022

024

020

018

016

014

012

010

008

006

004

002

(a)

CO2 fraction

022024026

020018016014012010008006004002

(b)

CO2 fraction

022

024

020

018

016

014

012

010

008

006

004

002

(c)

CO2 fraction

022

024

026

019

017

015

013

011

009

006

004

002

(d)


00 01 02 03 04 05

000

005

010

015

020

025

030

CO2 m

ass f

ract

ion

()

Axial position (m)

a = 10a = 14

a = 18a = 22




4 Conclusions




O2 fraction022

020

018

016

014

012

010

008

006

004

002

(a)

O2 fraction022

020

018

016

014

012

010

008

006

004

002

(b)

O2 fraction022

020

018

016

014

012

010

008

006

004

002

(c)

O2 fraction022

020

018

017

015

013

011

009

007

006

004

002

(d)


00 01 02 03 04 05ndash002

000002004006008010012014016018020022024

O2 m

ass f

ract

ion

()

Axial position (m)

a = 10a = 14

a = 18a = 22





Nomenclature







Data Availability




Acknowledgments



References



















































T (K)

1700

1573

1445

1318

1191

1064

936

809

682

555

427

300

(a)

T (K)

1600150014001300120011001000900800700600500400300

(b)

T (K)1700

1573

1445

1318

1191

1064

936

809

682

555

427

300

(c)

T (K)1600

1482

1364

1245

1127

1009

891

773

655

536

418

300

(d)


00 01 02 03 04 05

200

400

600

800

1000

1200

1400

1600

Tem

pera

ture

(K)

Axial position (m)

a = 10a = 14

a = 18a = 22






CO fraction

016

015

013

012

011

010

008

007

006

005

003

002

(a)

CO fraction

014013012010009008007006005004003002001

(b)

CO fraction

012013

011010009008007006005004003002001

(c)

CO fraction

010

011

009

008

007

006

005

004

003

002

001

(d)


00 01 02 03 04 05ndash001

000

001

002

003

004

005

006

007

008

CO m

ass f

ract

ion

()

Axial position (m)

a = 10a = 14

a = 18a = 22





CO2 fraction

022

024

020

018

016

014

012

010

008

006

004

002

(a)

CO2 fraction

022024026

020018016014012010008006004002

(b)

CO2 fraction

022

024

020

018

016

014

012

010

008

006

004

002

(c)

CO2 fraction

022

024

026

019

017

015

013

011

009

006

004

002

(d)


00 01 02 03 04 05

000

005

010

015

020

025

030

CO2 m

ass f

ract

ion

()

Axial position (m)

a = 10a = 14

a = 18a = 22




4 Conclusions




O2 fraction022

020

018

016

014

012

010

008

006

004

002

(a)

O2 fraction022

020

018

016

014

012

010

008

006

004

002

(b)

O2 fraction022

020

018

016

014

012

010

008

006

004

002

(c)

O2 fraction022

020

018

017

015

013

011

009

007

006

004

002

(d)


00 01 02 03 04 05ndash002

000002004006008010012014016018020022024

O2 m

ass f

ract

ion

()

Axial position (m)

a = 10a = 14

a = 18a = 22





Nomenclature







Data Availability




Acknowledgments



References




















































CO fraction

016

015

013

012

011

010

008

007

006

005

003

002

(a)

CO fraction

014013012010009008007006005004003002001

(b)

CO fraction

012013

011010009008007006005004003002001

(c)

CO fraction

010

011

009

008

007

006

005

004

003

002

001

(d)


00 01 02 03 04 05ndash001

000

001

002

003

004

005

006

007

008

CO m

ass f

ract

ion

()

Axial position (m)

a = 10a = 14

a = 18a = 22





CO2 fraction

022

024

020

018

016

014

012

010

008

006

004

002

(a)

CO2 fraction

022024026

020018016014012010008006004002

(b)

CO2 fraction

022

024

020

018

016

014

012

010

008

006

004

002

(c)

CO2 fraction

022

024

026

019

017

015

013

011

009

006

004

002

(d)


00 01 02 03 04 05

000

005

010

015

020

025

030

CO2 m

ass f

ract

ion

()

Axial position (m)

a = 10a = 14

a = 18a = 22




4 Conclusions




O2 fraction022

020

018

016

014

012

010

008

006

004

002

(a)

O2 fraction022

020

018

016

014

012

010

008

006

004

002

(b)

O2 fraction022

020

018

016

014

012

010

008

006

004

002

(c)

O2 fraction022

020

018

017

015

013

011

009

007

006

004

002

(d)


00 01 02 03 04 05ndash002

000002004006008010012014016018020022024

O2 m

ass f

ract

ion

()

Axial position (m)

a = 10a = 14

a = 18a = 22





Nomenclature







Data Availability




Acknowledgments



References



















































CO2 fraction

022

024

020

018

016

014

012

010

008

006

004

002

(a)

CO2 fraction

022024026

020018016014012010008006004002

(b)

CO2 fraction

022

024

020

018

016

014

012

010

008

006

004

002

(c)

CO2 fraction

022

024

026

019

017

015

013

011

009

006

004

002

(d)


00 01 02 03 04 05

000

005

010

015

020

025

030

CO2 m

ass f

ract

ion

()

Axial position (m)

a = 10a = 14

a = 18a = 22




4 Conclusions




O2 fraction022

020

018

016

014

012

010

008

006

004

002

(a)

O2 fraction022

020

018

016

014

012

010

008

006

004

002

(b)

O2 fraction022

020

018

016

014

012

010

008

006

004

002

(c)

O2 fraction022

020

018

017

015

013

011

009

007

006

004

002

(d)


00 01 02 03 04 05ndash002

000002004006008010012014016018020022024

O2 m

ass f

ract

ion

()

Axial position (m)

a = 10a = 14

a = 18a = 22





Nomenclature







Data Availability




Acknowledgments



References


















































4 Conclusions




O2 fraction022

020

018

016

014

012

010

008

006

004

002

(a)

O2 fraction022

020

018

016

014

012

010

008

006

004

002

(b)

O2 fraction022

020

018

016

014

012

010

008

006

004

002

(c)

O2 fraction022

020

018

017

015

013

011

009

007

006

004

002

(d)


00 01 02 03 04 05ndash002

000002004006008010012014016018020022024

O2 m

ass f

ract

ion

()

Axial position (m)

a = 10a = 14

a = 18a = 22





Nomenclature







Data Availability




Acknowledgments



References



















































Nomenclature







Data Availability




Acknowledgments



References

















































































Documents

Effect Analysis on Combustion and Emission Characteristics