Axial transport and residence time of MSW in rotary kilns
Part I.Experimental
S.-Q.Li a,b,*,J.-H.Yan a ,R.-D.Li a ,Y .Chi a ,K.-F.Cen a
a Department of Energy Engineering,Zhejiang University,Hangzhou 310027,PR China b
Department of Thermal Engineering,Tshinghua University,Beijing,100084,PR China
Received 17October 2000;received in revised form 28December 2001;accepted 31December 2001
Abstract
Experiments on the influences of operational variables on the axial transport of both heterogeneous municipal solid waste (MSW)and homogenous sand are conducted in a continuous lab-scale rotary kiln cold https://www.doczj.com/doc/308288795.html,pared with sand,the residence time of MSW has a relatively large discrepancy with the ideal normal distribution due to the trajectory segregation of MSW components.The residence time at different axial zone is quite different due to the varied bed depth profile along the kiln length.MSW has a longer mean residence time (MRT)and a lower material volumetric flow (MVF)than sand because of the higher h d than sand.The increment of both rotating speed and kiln slope reduces MRT,and increases MVF.Exit dam has a significant impact on the MRT and the influence of internal structure group consisting of various axial ribs and circular ribs is mainly determined by the height of circular ribs.Inside wall roughness also has effect on MRT through changing the bed regimes.For a case with the certain inlet and exit bed depths,the product of MRT and MVF holds at a constant within the limits of experimental errors in spite of the changing experimental variables.D 2002Published by Elsevier Science B.V .
Keywords:Rotary kiln;MSW;Axial transport;Mean residence time;Material volumetric flow
1.Introduction
Rotary kilns have been widely employed in chemical and metallurgical industries as heterogeneous noncatalytic gas–solid reactors.The typical applications include drying or heating of wet solids,mixing or grinding of powders,calcining of limestone,clinkering of cementitious materials,reducing of iron ore or ilmenite,etc.[1–3].Rotary kilns continue to find new applications in such gas–solid reac-tions,despite challenges from newer and more specialized reactors such as fluidized bed and spouted bed.
In recent years,rotary kilns have played an important role in the thermochemical treatment of municipal solid wastes (MSW).Rotary kiln system is one of the most promising incineration processes since it can simultane-ously treat wastes as liquids or solids of various shapes and sizes and easily achieve the flexible adjustment by altering kiln inclination,rotational speed,etc.Rotary kiln as a primary gasification chamber,followed by a secon-dary combustion chamber,can fulfil the complete destruc-tion and detoxification of hazardous wastes,meanwhile minimize emissions of dioxins and heavy mental.All these unique features enable rotary kiln irreplaceable in MSW incineration.‘Siemens Schwelbrenn’,‘Noell Conversion’and ‘Westinghouse O’Connor’processes are updated rep-resentatives of rotary kiln incinerators [4,5].
Pyrolysis,on the other hand,is an attractive alternative to incineration as a waste treatment option with respect to minimum environmental emissions and maximum resource recovery [6,7].Rotary kiln pyrolyser also has many unique advantages over other types of reactors.For instance,slow rotation of inclined kiln enables the well mixing of wastes,thereby the more uniform pyrolytic products.Also,the flexible adjustment of residence time can make pyrolysis reaction perform at a perfectly optimum condition conven-iently.With a view to different resource recovery option,rotary kiln can be properly designed to yield mainly the synthesis gas,e.g.,‘Landgard’Process [8],or to make the high calorific tars as well as porous carbon black,e.g.,‘Kobe Steel’Process [9].
Mean residence time (MRT)of solids through rotary kiln is one of the most important parameters,which not only directly influences mass and heat transfer,but also deter-
0032-5910/02/$-see front matter D 2002Published by Elsevier Science B.V .PII:S 0032-5910(02)00014-1
*
Corresponding author.Tel.:+86-10-62782108.E-mail address:lishuiqing@https://www.doczj.com/doc/308288795.html, (S.-Q.Li).
https://www.doczj.com/doc/308288795.html,/locate/powtec
Powder Technology 126(2002)217–
227
mines chemical reaction degree of gas and solid phase.In order to optimize the design and operation of rotary kiln,it is necessary to develop the simplified empirical expressions to enable the proper predicting of the volumetric flow of material(MVF)as well as MRT.Sullivan et al.[10] originally conducted the experimental research on the sol-ids’MRT in rotary cylindrical kiln and derived the empirical equation of MRT correlating various operational variables, kiln geometry parameters and material properties.Subse-quently,Va`hl and Kingma[11]and Kramers and Kroock-ewit[12]made further experiments on the holdup as well as MRT in a horizontal or inclined cylinder,respectively.The effect of internal structures is one of remarkable research community.Chatterjee et al.[13]studied the effect of ring formation,Matchett and Sheikh[14]studied the effect of both number and angle of axial flight,and Rutgers[15] considered the influences of shapes of kiln entrance and exit end faces.Furthermore,the residence time distribution (RTD)in rotary drums were researched by Abouzeid and Fuerstenau[16]and Sai et al.[17]adopting tracer stimulus-response techniques,or by Wes et al.[18]using atomic absorption spectroscopy methods.In addition,as the prac-tical field-scale rotary kiln was concerned,Groen et al.[19] performed corresponding investigations in a high-temper-ature kiln,while Schofield and Glikin[20]studied them in an intensive gas-flow fleeting kiln.
More recently,Wightman and Muzzio[21]emphasized that a research community focusing on the segregation of multimixed particles in rotary cylinder.Donald and Rosse-man[22]firstly performed experimental studies in a hori-zontal system and identified three patterns of segregation: radial,axial and end longitudinal.Gupta et al.[23]described qualitative mechanisms of axial segregation,stating that a difference in the dynamic reposing angles of two pure components is a necessary(though not sufficient)condition of band formation.Nakagawa et al.[24]recently employed magnetic resonance imaging to study axial segregation. Boateng and Barr[25]and Bridgewater et al.[26]studied the mechanism of radial segregation,respectively.
However,previous researches on axial transport in rotary kilns are mostly concentrated on the studies of small cementitious and metallurgical particles,which are rela-tively homogeneous in nature.Although rotary kilns have been extensively used as reactors for MSW incineration or pyrolysis,so far,there have been few attempts on extrap-olating the experiences and correlation developed from homogeneous materials to heterogeneous MSW.In this part,comparative studies are conducted between homoge-neous sand and irregular MSW in a rotary kiln cold simulator(I.D.0.3?1.8m).Impacts of material character-istics(in terms of the dynamical angle of repose),kiln geometry characteristics(i.e.,roughness of kiln wall,exit-end dam and internal structures)and operational parame-ters(i.e.,kiln inclination and rotational speed)on both MRT and MVF are examined.Simplified formulas of MRT and MVF are proposed on the basis of the experiment results in Part II of this work.
2.Experimental
2.1.Setup
A cold simulator of rotary kiln,0.3mm in diameter and
1.8mm in length,shown schematically in Fig.1,was employed for the experiments.The cylinder was made of plexiglass so that the solid motion can be viewed.The rotational speed is variable within the range of0.5–10rpm (revolution per minute).The angle of kiln inclination can be easily adjusted between0j and5j by altering the height of the supporter at kiln inlet end.The feed rate of materials was adjusted to a certain amount that keeps the inlet depth of the solids on a desired value during each run.That is,the inlet depth of solid bed responds to the feed rate of materials, which is practically equal to the flow rate of materials under the steady state,one to one,under the same operational conditions.Therefore,the inlet bed depth instead of material feed rate were selected as one of the operating parameters, which was kept at70mm in all runs.
In order to study the impact of internal structures on solid material motion,axial ribs and circular ribs were specially designed,as shown in Fig.2.The grouped types
and Fig.1.Schematic of rotary kiln cold simulator((1)Funnel,(2)Belt conveyor,(3)Tracer addition point,(4)Feed chute,(5)Rotary cylinder,(6)Position plate,(7)Belt wheel,(8)Position wheel,(9)Jockey wheel,(10)Slope angle adjustor,(11)Supportor,(12)Varible motor,(13)Exit chute,(14)Sample collector).
S.-Q.Li et al./Powder Technology126(2002)217–227
218
geometric factors of the different kinds of axial ribs and circular ribs are listed in Table1.
2.2.Materials
Two categories of materials were employed for experi-ments.One was reconstituted MSW consisting of49.9wt.% wood chips,17.0wt.%paper plates and33.1wt.%waste tyres.The mixture has irregular shape,size and heteroge-neous property.Also,homogeneous sand was used as another category for a contrast,which has higher density, regular shape and similar size.The physical properties of both kinds of materials are given in Table2.
As was reported in earlier literatures[11–20],the bulk characteristics of solids in terms of the dynamic angle of repose,h d,exert significant influences on the transport and mixing of the solids in the kiln.Here h d is measured according to the Rotating Drum-Method(Henein et al.
[27]).This measurement is done under one of the most general bed rotation cases of the kiln,rolling regime,and it can reflect the real dynamical bulk characteristics of solids in kiln.For all h d measuring of various materials,the kiln rotates at4rpm and fill ratio of solids in the kiln is about 15%–20%.h d of sand is about29.7j while that of MSW mixture is48.5j.
In order to study the influence of wall roughness on MRT and MVF,the inside kiln wall are covered by the finer or coarser emery cloths.The wall friction factor of solids is defined as the tangent function of the wall friction angle.The latter is measured by a special shear-plate-analyzer with an easy adjusting shear angle.A plate,which has the same roughness with the tested wall,is fixed on the adjustable shear plate.A layer of tested solids is laid on the plate.Then,the plate is gradually tilted until the solids begin to fall along it.At that time,the slope of the plate with respect to the horizontal line is just the wall friction angle of solids.As shown in Table2,compared to the smooth inside wall,the friction coefficient,f,increased dramatically(69–243%)with finer emery cloth setting. However,f increased only about6–25%from the finer emery cloth to the coarser one.2.3.Experimental methods
To determine MRT and MVF,the system must be adjusted to achieve the steady state,which is reached when the output of materials is equal to the feed rate of materials. The steady-state flow rate of materials,volumetric or molar, was measured by collecting sample successively within a certain time and quantifying it.As is widely known,the residence time of solids through rotary kiln is not a constant, but a probability distribution.Hence,the mean and variance of residence time are experimentally obtained by the stim-ulus-response techniques of tracers.Generally,the method for RTD measurement of MSW is hardly available in current literatures,though that of homogeneous sand has been described in detail[16–18].In this work,experiments were taken by introducing the dyed tracers consisting of9wood chips,15paper plates and36waste tyres.The ratios of three kinds of tracers are47.9,16.9and35.2wt.%,which are quite similar to those of original mixed wastes(i.e.,49.9 wt.%wood chips,17.0wt.%papers and33.1wt.%tyres).In fact,it is difficult to feed all tracers to kiln inlet end at the same time.Also,it is infeasible to label every tracer and measure its time one by one in such a short time interval. Thus,all tracers are divided into three groups and dyed red, white and yellow(each of which consists of3wood chips,5 papers and12tyres).As the steady state is reached,three groups of tracers are successively fed to the kiln inlet and the corresponding inlet time for each group is recorded.At the kiln outlet,they were collected after a certain time interval,until all tracers finished their excursion through the kiln.Meanwhile,the residence time of tracers in each sample interval was recorded(here,the inlet-time differ-ences of three group were taken into account).The mean and variance of residence time of the tracers are expressed below:
MRT c
X I
i?1
t i EeD t iT;e1Tr2c
X I
i?1
et iàMRTT2EeD t iT;e2TTable1
The grouped types and geometric factors of internal structures
Group No.Axial ribs Circular ribs
Number Height
(mm)
Number Height
(mm) Exit dam1––130 Exit dam2––150
12b-4n1220430
12b-7n1220730
12n-4n1210430
12b-4b12204
50 Fig.2.Schematic of internal structures((1)Cylinder,(2)Circular ribs,(3)
Longitudinal ribs).
S.-Q.Li et al./Powder Technology126(2002)217–227219
where I is the sequence of sampling interval,D t i is the interval of the i st sampling interval,and t i is the retention time of tracers in the i st interval.E (D t i )can be expressed as the ratio of the number of tracers in i st sampling interval to that of the total tracers,i.e.:E eD t i T?N eD t i T=
X I i ?1
N eD t i T:e3T
Usually,the relative variance is used to express the
dispersing extent of RTDs,which satisfies the relation:r 2r ?r 2=MRT 2:
e4T
3.Results and discussions
Table 3summarizes the detailed experimental results for MRT (together with r and r r )and MVF of the MSW in rotary kiln simulator with various rotating speeds,kiln slopes,exit-end dams,internal structures and walls of different roughness.In the following sections,the effect of each variable both on MRT and MVF will be discussed accordingly.
3.1.Residence time distribution of MSW and sand The previous studies on residence time of solids in rotary kiln are scarcely concentrated on the heterogeneous MSW,but on the homogeneous particles instead.For instance,Abouzeid and Fuerstenau [16]concluded that residence time of dolomites in rotary kiln is approximately subjected to a normal distribution by employing the axial dispersion model.The comparison between experimental results and theoretical calculation for RTD of both sand and MSW are shown in Figs.3and 4,respectively.As for sand,the probability of tracers by experiment in each sample interval (D t i )fits well with the theoretical normal distribution function.However,it is noted that,for MSW,there exists a relatively large discrepancy between exper-imental value and theoretical curve,other than r r 2of MSW is much larger than that of sand under the same
condition.It can be explained that,as tracers consist of three components with various shapes,sizes and densities,the variance in residence time would arise from axial segregation instead of axial mixing (particle collision).In fact,the axial segregation causes the deviation of meas-ured RTD from the normal distribution (this view will be further verified in Part II of this work).In addition,the alternate band formation of the various components (i.e.,the visible axial segregation)that has been studied and emphasized in a batch kiln system by some investigators [21–24]does not occur in this experiment.According to Donald and Rosseman [22],the alternate band formation in batch system may not arise in continuous system where the length of system is not adequate for particles to demix.Gupta et al.[23]stated that a difference in h d of all pure components at a particular rotation speed is one of the necessary (though not sufficient)conditions of band formation.From Table 2,the h d difference among three components of MSW is not significant.The rotating speed is only an order of magnitude smaller than that in the study of Gupta et al.Thus,it is induced that the axial segregation of MSW in kiln won’t be violent enough to form alternate bands,especially for such a system with a limited ratio of length to diameter (L /D =6).
The detailed r and r r of RTD of MSW under various rotating speeds,kiln slopes,exit-end dams,internal struc-tures and wall roughness are given in Table 3.Much valuable information can be obtained as follows.(1)Increasing rotating speed or kiln slope leads to relatively slight increment of r ,while r r varies or keeps in a narrow range from 0.02to 0.05.(2)The usage of exit dam can also increases r or r r ;but the impact on variance is less appreciable than that on MRT.(3)Employment of internal structures promotes both r and r r remarkably by one order of magnitude (e.g.,r r from range [0.02,0.05]to range [0.2,0.4]).However,it must be stated that the measuring error of RTD’s r and r r is quite high due to the segregation of MSW properties.Meanwhile,the measuring precision of both MRT and MVF can doubtlessly reach an expected level because of their statistical averaged characteristics.Therefore,more attention is paid to discussions on MRT/MVF rather than r /r r in the following paper.
Table 2
Summary of properties,bulk characteristic and wall friction factors of materials Materials Shapes Bulk density (kg/m 3)True density (kg/m 3)Sizes (mm)h d (j )f 1f 2f 3**Wood chips Cylindrical 371.5646.0U 25?3047.30.5250.9020.941Paper plates Tabulate 104.5691.730?30?351.90.563 1.930 2.331Waste tyre Arcuate 278.71020.010?5?3052.90.4210.941 1.102Mixed MSW *–
225777.6–
48.50.480 1.003 1.251Sand
Nodular
1342
2660
1.0–
2.0
29.7
0.407
0.724
0.768
*Mixed MSW consist 49.9wt.%woods,17.0wt.%papers and 33.1wt.%tyres.
**f 1,f 2,f 3are wall friction factor of solids with none,finer and coarser emery cloth setting on inside wall.
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220
3.2.Axial velocity distribution along kiln length
For end-open system,as the bed depth and the fill ratio of solids in cross-section are different at the different axial position,the axial cascading velocity of solids is not constant along the kiln axis.That is,the residence time in different zone along kiln length is quite different.Figs. 5and6give the axial velocity of sand and MSW under different axial points,respectively.It can be seen that the axial velocity of particles increases along the axial direc-tion.It is due to the decrement of the bed depth or the fill ratio along the kiln axis.Thus,according to the mass conservation theory,d(q uA)/d x=0,the axial velocity along kiln length increases gradually.By the way,as for the practical rotary kiln reactor,it has various reaction zones along the axis and the solids have different properties in every zone.Thus,it is essential to know the detailed residence time of the solids in each zone.However,up to now,nearly all the experimental/theoretical works of solid transport are concentrated on the overall residence time through the kiln inlet to outlet.The residence time of solid passing a special reaction zone can be obtained by integration of the bed axial velocity along the age of this zone,t i?m z i z
ià1
d z=uezTwher
e z represents kiln axis and i
Table3
Overall experimental data for MRT and MVF of MSW with different variables
Run number Internal structure Rotated rate(rpm)Inclination(j)MRT(min)MVF(l/min)r r r
1Smooth wall2 2.4011.53 1.560.260.023 23 2.408.25 2.620.200.024 34 2.40 5.58 3.730.180.026 44 1.817.05 2.530.230.043 540.6211.28 2.180.540.049 66 2.40 4.07 4.240.160.042 78 2.40 3.27 5.500.120.037 8Finer emery cloth setting3 2.4010.98 2.04 2.650.24 94 2.408.87 3.09 2.020.23 104 1.818.78 2.09 1.750.20 1140.6216.80 1.16 3.840.24 126 2.40 6.20 4.58 1.190.19 138 2.40 4.20 4.620.850.20 14Coarser emery cloth setting3 2.4011.83 1.60 2.100.18 154 2.408.40 2.80 1.700.20 164 1.819.47 1.96 2.230.24 1740.6212.30 1.69 3.820.23 186 2.40 6.15 3.82 1.430.23 198 2.40 4.95 4.270.970.20 20Exit dam1(30mm)3 2.4013.15 1.640.430.033 214 2.409.93 2.440.370.037 224 1.8112.27 1.470.370.030 238 2.40 5.92 4.220.300.051 24Exit dam24 2.4014.80 1.560.670.045 2512b-4n2 2.4019.67 1.27 4.480.23 263 2.4013.90 1.71 3.290.24 274 2.409.75 2.16 2.260.23 284 1.8112.67 2.00 3.560.28 2940.6224.67 1.188.260.34 3012b-7n2 2.4016.95 1.02 4.360.26 313 2.4015.90 1.69 4.110.27 324 2.4011.62 2.33 2.450.21 334 1.8115.12 2.13 4.340.29 3440.6221.670.987.320.33 3512n-4n2 2.4019.67 1.33 5.570.28 363 2.4012.08 1.84 3.240.27 374 2.409.78 2.71 2.140.22 384 1.8115.20 1.91 4.670.31 3940.6222.37 1.20 6.890.33 4012b-4b2 2.4024.920.87 6.270.25 413 2.4015.85 1.47 2.940.19 424 2.4012.03 2.04 2.610.22 434 1.8115.95 1.38 3.920.25 4440.6226.750.847.650.27 *The inlet depth of solid bed in all runs is70mm(23%of inner diameter).
S.-Q.Li et al./Powder Technology126(2002)217–227221
the zone’s sequence.Axial velocity,u (x ),can be calculated through the empirical correlations (Lebas et al.[28],Perron and Bui [29]).
3.3.Influences of particle characteristics on MRT and MVF
The comparison of MRT and MVF between sand and MSW under the same conditions is shown in Figs.7and 8,respectively.The MRT of MSW is greater than that of sand for all runs.From the regress curve in Fig.7,it is obtained that the former is about 1.43times of the latter.Contrarily,MVF of MSW is less than that of sand with the multiple of 0.625(1/1.48).From Table 2,it can be seen that sin h d of MSW is 1.50times of that of sand.Thus,the conclusion is drawn:the material’s characteristics exerts its influences on the MRT and MVF mainly in terms of h d ;MRT increases approximately in linear fashion as sin h d of material increases,while MVF is subjected to the inverse proportional function of sin h d .These conclusions will be
verified subsequently by the theoretical analysis in Part II of this work.
3.4.Influences of rotating speed and kiln slope
The impact of rotating speed on the MRT and MVF of heterogeneous MSW is shown in Fig.9.As rotational speed increases from 2to 8rpm,MRT decreases nearly in inverse proportional fashion of rotating speed,while MVF increases gradually.These conclusions are consistent with those acquired from the homogenous small particles by others [11,30].It may be explained that the axial transport of solids mainly occurs in the active layer of bed surface,while solids in the stagnant region under bed surface only turn around the kiln axis without any axial displacement.As the rotational speed increases,the times of a particle entering the active layer per unit time increases,which further results in the increase of the particle’s axial displacement per unit time (namely,particle’s axial velocity)[18,31].Therefore,MRT decreases and MVF
increases.
Fig.3.Residence time distribution of
sand.
Fig.4.Residence time distribution of
MSW.Fig.5.Axial speed distribution of sand along kiln
axis.
Fig.6.Axial speed distribution of MSW along kiln axis.
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222
Fig.10indicates the effect of kiln slope on the transport behavior of MSW.When kiln slope angle increases from 0.62j to 2.40j ,the MRT decreases in an approximately linear fashion from 11.28to 5.58min,while MVF rises from 2.18to 3.73l/min.It is possible that the increasing kiln inclination causes the increment of the gravitational force component in the axial direction of individual particle during its cascading,i.e.,the increment of the solid axial velocity,which finally causes MRT to decrease and MVF to increase.3.5.Influences of exit-end dams
The exit-end dam exerts significant influences on the MRT and MVF of solids in a rotary kiln.As shown in Fig.11,MRT of MSW and sand with the 30-mm dam (about 10%of inner kiln diameter)are 78.0%and 71.4%longer than that with no end constriction,respectively.As for a higher 50-mm dam (about 16.7%of inner diameter),the
corresponding augment is 165%and 138%for MSW and sand,respectively.The higher height of dam has,the more remarkable effect it has on MRT.The affecting extent made by the 50-mm dam is almost twice of that made by the 30-mm dam.The reasons for above conclusions lie in two aspects.First,the usage of exit dam reduces the slope of the solid bed and then the axial cascading velocity of particles.On the other hand,it causes the increment of bed depth in kiln.This increment of flow area in cross-section will decrease axial cascading velocity,either.Finally,the combi-nation of two reasons above cause the remarkable increase of MRT.In addition,MVF decreases when employing exit-end dam.As for the 30-mm dam,the reduction of MVF of MSW and sand are 34.5%and 27.9%,respectively,and for the 50-mm dam,the corresponding reduction is 58.3%and 35.2%(shown in Fig.12).It is doubtless that the usage of exit dam is an effective method to control the MRT and MVF of solids.However,it is noted that exit dam has no such apparent impacts on relative variance r r as it has on MRT,as seen from Table 3
.
https://www.doczj.com/doc/308288795.html,parison of MRT between MSW and
sand.
https://www.doczj.com/doc/308288795.html,parison of MVF between MSW and
sand.Fig.9.Effect of rotational speed on MSW transport
behavior.
Fig.10.Effect of kiln slope angle on MSW transport behavior.
S.-Q.Li et al./Powder Technology 126(2002)217–227223
3.6.Influences of the internal structures
The internal structures inevitably affect the axial trans-port of solids [13,14].The impacts of internal structures on MRT are different with various groups consisting of a certain number of axial ribs or circular ribs.Figs.13and 14illustrate the influences of four groups of internal structures (listed in Table 2)on the MRT of MSW and sand,respectively.It is found that all these four kind of internal structures seriously increase MRT of solids.The detailed conclusions are drawn:as the number of circular ribs in an internal structure group increases (12b-4n !12b-7n),the MRT in 12b-7n case is slightly longer than that in 12b-4n case for both MSW and sand;as the height of circular ribs increases from 30to 50mm (12b-4n !12b-4b),the incre-ment of MRT from 12b-4n to 12b-4b case is more remark-able.However,with the increasing height of axial ribs from 10to 20mm (12n-4n !12b-4n),the MRT changing ten-dency of MSW and sand is inconsistent or inexplicit.According to above,it is concluded that influences of the internal structure group on MRT are dependent on the height of circular ribs,while the impacts of the height of axial ribs is inexplicit.The influence of circular ribs on MRT can be explained by their similarity to the exit dam whose influence has been already tested to be remarkable.The impact of axial ribs on MRT is quite complicated,which not only changes the solid’s dynamic angle of repose,but also kicks up some particles from the bed surface to the freeboard space.These conclusions can be verified by the experi-ments.For instance,the 30-mm exit dam promotes MRT with 78.0%;however,the internal structure groups labeled 12b-4n,12b-7n and 12n-4n,whose circular ribs is also 30-mm height,only promote the MRT in range of 75%to 108%with MSW under an condition of rotating speed at 4rpm and inclination at 2.40j (Fig.14).
Since the exit dam (regarded as one special circular rib)does not exert the same apparent effects on r r as it does on MRT,here,the great promotion by one-order of
magni-
Fig.11.Effect of exit end dam on
MRT.
Fig.12.Effect of exit end dam on
MVF.Fig.13.Effect of various internal structures on MRT of
MSW.
Fig.14.Effect of various internal structures on MRT of sand.
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224
tude of r r may be attributed to the presence of axial ribs (Table 3).
3.7.The influences of inside wall roughness
The inside wall’s roughness,designated by the wall friction factors of solids (f ),has significant effects on axial transport.Fig.15presents the variation of MRT with the various f .When the inside wall is smooth with f at 0.480,MRT is rather short.When f increases to 1.003(viz.the finer emery cloth is set on inside wall),MRT increases significantly.However,with further increase of f from 1.003to 1.251(the coarser emery cloth setting),the increment of MRT is not apparent.It can be explained that the variation of f greatly changes the bulk characteristics (in terms of variation of h d )and further changes the bed regimes of solids.As observed,the solid bed in a case of smooth wall may perform at a slumping regime,in which the solids cascade as periodic ‘avalanche’through the kiln and have a short MRT.When f increases to 1.003,h d increases from 48.5j to 58j and the rolling regime is well
formed.The variation of both h d and bed regimes greatly increases MRT.When f continues to increase to 1.251,h d slowly increases up to about 59.5j ,the rolling regime also dominates the bed behavior (that is,the advanced cataract-ing regime is not yet formed).Thus,the variation of MRT is small.In addition,the impact of f on MVF of MSW is shown in Fig.16.MVF decreases gradually with the increasing f ,and its changing tendency is contrary to that of MRT.
3.8.The relationship between MRT and MVF
As discussed above,when one of the variables,such as rotational speed,kiln slope,dynamic angle of repose and internal-structures,changes,the variation of MRT has the reverse tendency with that of MVF.It is apparent that the product of MRT and MVF is just the holdup of solids in kiln,which is expressed as Holdup =MRT ?MVF.Fig.17shows the product of MRT and MVF (i.e.holdup)under different run,in which the values of MRT and MVF are obtained from Table 3.In a case of smooth wall with open exit end,in spite of the changing of rotational speed or kiln slope,the product of MRT and MVF keeps around 19.7l,which implies that the overall fill ratio of solids to kiln vessel is a constant at 15%.As far as the internal-structures,such as 12b-4n,12b-7n and 12n-4n are considered,it holds around 25l (that’s,overall fill of solids reaches about 18f 19%).The employment of 12b-4n,12b-7n or 12n-4n not only similarly enlarges the exit-end bed depth from 0to 30mm (while the bed depth at kiln inlet holds 70mm),but also expands the bulk characteristics of solids along all kiln length.Thus,the holdup increases from 19.7to 25.3l.Finally it is drawn that the overall fill ration or holdup of solids within kiln is just relevant to the inlet bed depth,exit bed depth and usage of internal structures,but independent of some operational parameters such as rotational speed or kiln slope.This conclusion is much meaningful to the scale-up or design rotary kiln
reactor.
Fig.17.Relationship between MRT and
MVF.
Fig.15.Effect of inside wall roughness on MRT of
MSW.Fig.16.Effect of inside wall roughness on MVF of MSW.
S.-Q.Li et al./Powder Technology 126(2002)217–227225
4.Conclusion
(1)The reconstituted MSW consists of49.9wt.%wood chips,17.0wt.%paper plates and33.1wt.%waste tyres. The dynamic angle of repose(h d)reflects the bulk character-istics of solids in kiln.h d of MSW is48.5j and h d of the contrastive sand is about29.3j.The value of h d increases with the enhancement of wall roughness,but is independent of the drum rotation speed.
(2)The distribution of residence time of MSW arises from the axial segregation of different components,but not the axial collisions.It results in a relatively large discrep-ancy of experimental RTD with ideal normal distribution. The variance(r or r r)of MSW is greater than that of sand. It is noted that the known phenomenon of alternate band formation does not occur in such a continuous system.
(3)The axial cascading velocity of particles increases along the axial direction due to the decrement of the bed depth or the fill area along the kiln axis.Thus,it is essential to know the detailed residence time of the solids in each divided zone besides that of the whole kiln,which implies incoming research intensive.
(4)The difference of the MRT/MVF between the hetero-geneous MSW and regular sand is related to their dynamic angles of repose.MRT is approximately a proportion function of sin h d,while MVF is an inverse proportion function of sin h d.
(5)Increasing either rotating speed or kiln slope results in the decreasing MRT and increasing MVF.These variables are both considered as flexible parameters to adjust the kiln peformance in the practice.The r of RTD shows the same fashion as MRT with various rotating speed or kiln slope, while r r keeps in a narrow range from0.02to0.05.
(6)The exit dam has remarkable impact on MRT of solids; thus,it can also be used as an adjusting tool of the kiln.Impact of internal structures,which are composed of axial ribs and circular ribs,on MRT mainly depends on height of circular ribs.However,exit dam(or circular ribs)does not exert the same apparent impact on r r as it does on MRT.It is implied that the axial ribs will have great effect on r r.
(7)The effect of roughness of inside wall on MRT and MVF can be explained by that the variation of f between the wall and the solids directly changes the bulk characteristics of the solids in kiln and further changes the motion regime of the bed.
(8)For a case with given inlet and exit bed depths,the holdup in terms of the product of MRT and MVF holds at a constant within the limits of experimental errors.The presence of internal structures increases the holdup of solids.
Acknowledgements
This research was supported mainly by Nation Natural Science Funds of China(No.50076037)and partially by Zhejiang provincial National Science Funds of China(No. RC99041).We are grateful to Dr.A.-M.Li for helpful discussion about rotary kiln transport processes.The contribution of Dr.J.T.Huang and Z.X.Zhang to this work is gratefully acknowledged.
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CHAPTER ONE accidentally意外的，偶然的 act行动;扮演（角色）atmosphere大气层；气氛 author作者 billion（英德）万亿；（美法）十亿burn燃烧 CFC氟利昂 burn up烧得更旺，烧毁 carbon dioxide 二氧化碳 compare比较，比作 consumer消费者 green consumer环保消费者 cover涉及，包括 damage损害，损毁 destruction破坏，毁坏 dioxide二氧化物 do with处理 drown溺死 erosion侵蚀，腐蚀 flood淹没，洪水 flooding洪水泛滥 fuel燃料 greenhouse温室 layer层 Greenhouse Effect温室效应 keep in把....关在..里面 level 水平高度，级别 lifeless无生命的 malaria疟疾 massive巨大的，大量的 nitrogen氮 occur出现，存在，发生 ozone臭氧 petrol汽油 protective保护的 rain forest（热带）雨林 spray can喷雾罐 substance 物质 take in吸入，摄入 threat威胁 vital与生命有关的，极重要的warmth温暖 wrecked毁坏的 durian榴莲 leaded含铅的 motor机动的 solar-powered以太阳能为动力的unleaded不含铅的 canopy罩棚，覆盖物 ect. 等等 exhaust排出的废气 fume（难闻的）气 incinerator焚化炉 inform通知 inquire询问 classical古典的 comedy喜剧 preference偏爱 respond回答 club sandwich总会三明治CHAPTER TWO actually 实际上 aim目的 airline航空公司 Auckland奥克兰 Brazil巴西 change找头，零钱 check-out收银台 climate 气候 confident自信的 deeply深深地，极大地，强烈的dump（垃圾）堆 educational教育的 fence围栏，栅栏 flower-arranging插花 flyover立交桥 foreign外国的 friendship友谊 fund（为机构.项目等）拨款gap分离，差距 golf高尔夫球运动 hoot鸣响（喇叭，汽笛等）host（待客的）主人
六年级英语上册期末测试卷 时间：60分钟满分：100分+10分题号一二三四五六七八九十十一十二口语总分得分 听力部分(30分) 一、听录音，给下列图片排序。(5分) 二、听录音，选择正确的答句。(5分) ()1. A. The plants. B. The smoke. C. The fish. ()2. A. In the forest. B. In the zoo. C. In the sea. ()3. A. About ten minutes. B. About six hours. C. At ten o'clock. ()4. A. The Palace Museum and Big Ben. B. Big Ben and the British Museum. C. Big Ben and the Great Wall. ()5. A. They eat unhealthy food. B. They don't eat anything. C. They eat healthy food. 三、听录音，补全句子。每空一词。(10分) 1. Last summer, we ____________ to the ____________ Museum. 2. Don't eat ____________ much ____________！ 3. Beijing is ____________ the ____________ of China. 4. I'd like to ____________ about his ____________. 5. We recycle ____________ to help the ____________.
牛津小学英语六年级期末试卷 听力部分（30分） 一、听录音,选出你听到得内容.（听一遍）（10分） ( )1. A. earphone B. dairy C. handkerchief D. walkman ( )2. A.18th of October B. 6th of August C. 12th of July D. 8th of June ( )3. A. 33425 B. 33465 C. 32495 D. 33265 ( )4. A. all B. ago C. also D. as ( )5. A. rose B. race C. face D. science ( )6. A. talk about B. take a walk C. take on D. take photos ( )7. A. pick up B. get up C. stand up D. go up ( )8. A. three years ago B. thirteen years ago C. thirty years ago D. the third year ( )9. A. in your bedroom B. in the bathroom C. on your bed D. in the bag ( )10. A. a roll of film B. a pair of glasses C. a glass of milk D. a pair of trousers 二、根据所听句子,选择正确的答案.（听两遍）（10分） ( )1. A. It’s the 3rd of March. B. It’s Teachers’ Day. C. It’s Thursday ( )2. A. Thanks a lot B. How nice C. It was there a moment ago. ( )3. A. It was a pair of glasses. B. It’s a pair of glasses. C. They’re a pair of glasses. ( )4. A. It’s in the park. B. It means ‘No parking’ C. It was in the park. ( )5. A. Yes, it is. B. It’s not my handkerchief. C. It’s in my pocket. ( )6. A. It’s Sunday. B. It’s Sports Day. C. It’s the 8th of Oct. ( )7. A. in the classroom B. in the playground C. at home ( )8. A. Having a running race. B. Watching a running race C. Taking photos.
牛津上海版九年级英语下册Unit-
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九下Unit 6 单词短语归纳 １.实施，执行v 1. 承受压力 2．争吵n ２.集中于 ３.集中(注意力、精力等)于v 3.解决,处理 4.压力n 4.deaｌwｉth 5．是否5．担心 6.风险n6．防止，提防7．守卫,保卫 7.抵消,对消 8.取消，撤退，终止8. 忙于做某事 9.有希望的9.把....．抛在后面 10.强迫,迫使(某人做某事）1０.使．.．.．振奋起来 11.音乐会,演奏会１1.学着做,开始做 12．私人的１2.持乐观的态度13.不说话的，沉默的1３. 抵消,对消 1４.危害物，大敌１４．讲笑话 1５.鼓励,鼓舞15.去听音乐会 16.牙科医生 1７.沮丧的，消沉的，无精打采的aｄj 知识点 1.conduct v.实施；执行n_＿_＿___＿__指挥家 Ｃonducｔ a sｕrvey aｂｏｕt a ｈeaｌthy liｆｅstyｌe．____＿____＿___＿_＿_____＿＿___＿_____ cｏnduｃｔ此处用作及物动词,意为“实施，执行”。 我决定去执行一个任务__＿＿________＿______＿___________ 2.quaｒreｌn.争吵 ｈａｖe a ｑuａrrel ｗitｈsｂ．__＿_＿_＿__＿___＿__＿__ ｈavｅ a quaｒrｅl ａbｏｕt sth.______＿_______＿＿_＿__＿＿___＿ 1)他刚刚和他的最好的朋友吵架了______＿__＿____＿＿＿＿__＿__＿_＿______＿___ ２）他们为钱的事情吵架了___＿_＿_＿_____＿_______＿＿___________＿＿_＿ 3.pleasｕｒe 不可数名词，_＿_____＿____＿_＿_ aｄｊ___＿＿＿____ Dｏｉｎｇsｏmetｈiｎｇfor __＿_________＿___．
牛津英语小学六年级英语第一学期期末考试 一、把下列单词翻译成英语或者汉语（20分） 1、always__________________________ 2、member________________________ 3、yesterday________________________ 4、pavement______________________ 5、spend____________________________ 6、arrive________________________ 7、holiday__________________________8、special________________________ 9、collect__________________________10、fight__________________________ 11、开始__________________________12、剑____________________________ 13、电影院________________________14、成年人________________________ 15、大笑__________________________16、变化__________________________ 17、最喜爱的______________________18、足够的________________________ 19、健康的________________________20、宇宙飞船______________________ 二、把下列词组翻译成汉语或者英语。（20分） 1、几百年前________________________________ 2、去看电影___________________ _______________ 3、灭火_____________________________ 4、许多不同的工作____________________ ______________ 5、中秋节_______________________________ 6、足够的钱______________________ ______________ 7、一瓶水_______________________________8、成长，长大____________________ ______________ 9、去购物_______________________________10、在冰箱里_____________________ ______________
六年级英语试卷 听力部分（20%） 一、听录音，从A、B、C三个选项中选出你所听到的内容( 5% ) ( ) 1. A. pass B. past C. must ( ) 2. A. little B. letter C. litter ( ) 3. A. cook B. look C. book ( ) 4. A. taste B. last C. take ( ) 5. A. open B. over C. orange ( ) 6. A. coat B. come C. boat ( ) 7. A. water B. what C. watch ( ) 8. A. there B. where C. here ( ) 9. A. dance better B. sing better C. do better ( ) 10. A. shopping center B. middle school C. post office 二、听录音，给下列图片标上正确的序号（5% ） 三、听录音，从A、B、C三个选项中选择最佳答案（5% ） ( ) 1. A. It’s sunny. B. Fine, thank you. C. I like winter. ( ) 2. A. It’s windy. B. Winter. C. Yes, it is. ( ) 3. A. You’re welcome. B. Two stops. C. Take bus No. 5. ( ) 4. A. Thank you. B. On Zhongshan Road. C. Oh, I see. ( ) 5. A. Yes, it is. B. No, it isn’t. C. Yes, it does.
六年级英语(上)期末试卷 听力部分（30分） 一、听录音, 选出你所听到的单词或短语。（听两遍，共10题，每小题1分，计10分） （ ）1. A. litter （ ）2. A. smell （ ）3. A. sky （ ）4. A. sing （ ）5. A. ground （ ）6. A. project （ ）7. A. told （ ）8. A. too much （ ）9. A. threw （ ）10. A. cut down B. little B. still B. skin B. sign B. around B. protect B. hold B. so much B. throw B. put down C. letter C. spell C. slip C. song C. playground C. plastic C. cold C. too many C. through C. sit down 二、听录音， 给下列图片标上正确的序号。（听两遍，共5题，每小 题1分，计5分） （ ） （ ） （ ） （ ） （ ） 三、根据所听到的句子，选择合适的答句。（听三遍，共5题，每小题1分，计5分） ( ) 1. A. He read newspapers. B. She had a fashion show C. It was great fun. ( ) 2. A. Yes, I do. B. No, I didn’t. C. No, I can’t. ( ) 3. A. It’s Monday. B. It’s the second of February. C. It’s rainy.
9B牛津译林版Unit2知识点 1、In 1966, he went into space as command pilot of Gemini 8. He and David Scott managed to join two spacecraft together for the first time in space.(P22,lines9-12) 1966年，他作为“双子座8号”宇宙飞船的飞行指挥进入太空。他和戴维.斯科特成功地将两个航天器在太空首次交会对接 知识点：manage 的用法 1）完成(困难的事)；勉力完成 eg: In spite of his disappointment, he managed a weak smile. 尽管他很失望，他还是勉强露出一丝淡淡的微笑。 2） manage to do 成功做某事 eg: We managed to get to the airport in time. 我们设法及时赶到了机场。 3） manage with/without sb/sth 能解决(问题)；应付(困难局面等) eg: I don’t know how she manages on her own with four kids. 我真不知道她一个人是怎么养活她那四个孩子的。 2、However, on their way back to the Earth, the spacecraft began spinning out of control.(P22,lines12-13) 但是，在他们返回地球的途中，宇宙飞船开始旋转，失去控制。 知识点：control的用法 1）作动词，有“掌管，管理，控制”的意思。 eg：By the age of 21 he controlled the company. 他21岁就掌管了公司。 Parents should control what their kids watch on television. 父母应该限定孩子看什么样的电视节目。 2）作名词，有“权利，限制，管理”的意思。 eg: The party is expecting to gain control of the council in the next election. 该党期待着在下次选举中获得对地方议会的控制权。
六年级英语( 上) 期末试卷 听力部分（30 分） 一、听录音, 选出你所听到的单词或短语。（听两遍，共10 题，每小题1 分，计10 分） （）1. A. litter （）2. A. smell （）3. A. sky （）4. A. sing （）5. A. ground （）6. A. project （）7. A. told （）8. A. too much B. little B. still B. skin B. sign B. around B. protect B. hold B. so much C. letter C. spell C. slip C. song C. playground C. plastic C. cold C. too many （）9. A. threw （）10. A. cut down B. throw B. put down C. through C. sit down 二、听 录音， 给下 列图 片标 上正确的序号。（听两遍，共 5 题，每小题 1 分，计 5 分） （）（）（）（）（） 三、根据所听到的句子，选择合适的答句。（听三遍，共 5 题，每小题 1 分，计 5 分） ( ) 1. A. He read newspapers. B. She had a fashion show C. It was great fun. ( ) 2. A. Yes, I do. B. No, I didn ’t. C. No, I can ’t. ( ) 3. A. It ’s Monday. B. It ’s the second of February. C. It ’s rainy. ( ) 4. A. He could draw. B. He can draw. C. He likes drawing. ( ) 5. A. We can study hard. B. We can throw rubbish anywhere. C. We can ’t litter.
Unit 1 travel writer 游记作家 the American continents 美洲大陆 have an effect on… 对…造成影响 open up 开辟 go on a trip 去旅行 set up 建立；设立 trade routes （旧时的）商队路线，商船航线set sail 起航 the Ming Dynasty 明朝 be known as 被称为 as well as 也；还 a new age of ……的新时代 lead to 导致 an interview with sb. 对某人的采访compare…with… 把……与……对比 the Silk Road丝绸之路 Unit 2 summer camp 夏令营 thank-you email 感谢邮件 way of life 生活方式 international exchange 国际交流 be strange to sb. 对某人来说……不熟悉 in one’s spare time 在某人的空闲时间里 to a certain degree 在某种程度上 get used to 习惯于；适应 under the weather 略有不适；不得劲capital city 首都 national flag 国旗 full-time education 全日制教育 state school 公立学校 private school 私立学校 Unit 3 greenhouse effect 温室效应 harmful gas 有害气体 green consumer 绿色消费者 in danger 在危险中 let…in 允许……进入 as a result of 由于 result in 造成；导致 mountains of 许多；大量 take action 采取行动
学校 班级 姓名 考试号 . 密 封 线 内 请 不 要 答 题 小学英语毕业模拟卷 题号 听力部分 笔试部分 总分 一 二 三 四 一 二 三 四 五 六 得分 听力部分（共30分） 一、听录音，选择你所听到的内容（读两遍，10分） ( ) 1. A. king B. kilt C. quick ( ) 2. A. watch B. waste C. water ( ) 3. A. full B. thirsty C. hungry ( ) 4. A. doctor B. astronaut C. dentist ( ) 5. A. a nice place B. travel around C. a tidy and clean place ( ) 6. A. August 3rd B. October 3rd C. August 13th ( ) 7. A. plastic bags B. paper bags C. plastic bottles ( ) 8. A. Giraffe points at his neck B. Giraffe points at his long neck C. Giraffe points at his long nose. 二、听录音，根据所对话及问题，选择正确的图片。（读两遍，5分） ( ) 1. A. B. C. ( ) 2. A. B. C. ( ) 3. A. B. C. ( ) 4. A. B. C. ( ) 5. A. B. C. 三、听录音，按所听故事给下列图片标序号。（读两遍，8分） ( ) ( ) ( )
Unit l voyage n. 航行 repetition n. 重复 American adj. 美洲的 continent n. 大陆 *route n. 路线 discovery n. 发现 rise v．(rose，risen)变得更加成功（或重要、强大等）official n. 官员 develop v. 增强；加强 relation n. 关系；交往 trade n. 贸易 v. 以物易物；互相交换 foreign adj. 外国的 *fleet n. （统一调度的）船队；机群 Africa n. 非洲 Nowhere adv. 无处；哪里都不 silk n. 丝织物；丝绸 giraffe n. 长颈鹿 besides prep. 除……之外（还） development n. 发展；壮大 *region n. 地区 pioneer n. 先锋；先驱 people n. 民族；种族 wealth n. 财富 spread v. (spread,spread) 传播 open up 开辟 go on a trip 去旅行 set up 建立；设立 set sail 起航 (be) known as 被称为 as well as 也；还 lead to 导致 compare…with…把……与……对比 Unit 2 culture shock n. 文化冲击；文化休克 camp n. 度假营 *firework n. 烟火；烟花 *turkey n. 火鸡 international adj. 国际的 admit v. (常指勉强）承认 spare adj. 空闲的；空余的 degree n. 程度 fail v. 失败；未能（做到） manage v. 完成（困难的事）；勉力完成 idiom n. 习语；惯用语 everyday adj. 每天的；日常的 uniform n. 校服 whatever pron. 任何事物；一切事物 pink adj. 粉红色的
牛津小学英语毕业班水平模拟卷 （时间：90分钟满分：120分） 听力部分（30分） Ⅰ.听录音，选出你所听到的单词。（听一遍）（10分） ( )1. A. ball B. bike C. black ( )2. A. watch B. water C. world ( )3. A. boy B. job C. dog ( )4. A. class B. grass C. bus ( )5. A. warm B. cool C. hot ( )6. A. dress B. coat C. skirt ( )7. A. four B. seven C. eight ( )8. A. blue B. yellow C. red ( )9. A. mother B. sister C. brother ( )10. A. start B. far C. farmer Ⅱ.听录音，用数字给下列图片排序。（听两遍）（5分） Ⅲ听录音，选择正确的答案。（听两遍）（5分） ( ) 1.A. Goodbye. B. OK. C. Nice to meet you,too. ( )2.A. Yes,they do. B. Yes,I am. C. Yes,we are. ( ) 3.A. It's a book. B. It's mine. C. It's green. ( )4. A. All right. B. It's nine. C. You are welcome. ( )5. A.I like winter best. B. I like Art best.C. I like apple best. Ⅳ.听对话及问题，选择正确的答案。（听两遍）（5分） ( )1. A. Climbing. B. Dancing. C. Skating. ( )2. A. Yes,there is. B. No,there isn't. C. That's great. ( )3. A. There are two. B. There are three.C. There are four. ( )4. A. Go fishing. B. Play chess. C. Play basketball. ( )5. A. He is thirteen. B. He is fourteen. C. He is twelve. Ⅴ.听对话及问题，选择正确的答案。（听两遍）（5分） My name is Wang Bing. 1 am a boy. There are people in my family. They are my grandparents, my parents and me. My is a doctor. He likes growing flowers. My mother is a . She likes playing
牛津英语六B期末测试题（五） 一，选择题 1, What would you loke to have_______dinner ? A, at B, for C, with D, to 2, I don’t like meat_______fish . A, with B, into C, in D, to 3, Vegetables in the market are usually_______than those in the supermarket . A, much cheaper B, more cheap C, the more cheap D, cheapest 4, He made_______mistakes in his homework. A, a little B, few C, little D, much 5, There isn’t_______in the fridge.Let’s go to the supe rmarket and buy some. A, foods enough B,the food enough C,enough food D,the enough food 6, _______delicious the sandwich with ham and tomatoes are! A, What B, How C, What a D, How a 7,What does he need _______to help his mother with the housework ? A, do B, to do C, does D, doing 8, Kitty went to the _______food section to choose some yoghurt . A, freezen B, frozen C, freeze D,freezing 9, Have you_______a present for your grandma ? A, buy B, brought C, bought D, buying 10, A lot of people are buying T-shirts because they are_______sale . A, on B,in C, at D,of 11, _______do you like the soya milk ? Because it’s delicious . A,Why B,When C, What D, How 12, Shall we go to buy some fruit ? _______. A, Yes,we do B,That’s a good idea C,No,we can’t D, No,I don’t like 13, Steak usually tastes_______with black pepper sauce . A, well B, wonderfully C,nice D,sour 14, May I have_______coffee after dinner ? Sure , but only _______. A, some ,little B, any, little C,some,a little D, any , a little 15, Today is a good day _______our spring outing . A, to B, on C, at D, for 16, Let’s go swimming , _______? A, will you B, shall we C, do you D, do we 17, Why not _______up your hand when you want to ask question ? A, putting B, to put C, put D, puts 18, Have you got enough money _______this book ? A, buys B, buy C, buying D, to buy 19, I don’t like to have bread with jam for breakfast_______it’s too sweet . A, but B, and C, because D, so
牛津版小学六年级英语期末考试卷 本文从网络收集而来，上传到平台为了帮到更多的人，如果您需要使用本文档，请点击下载按钮下载本文档（有偿下载），另外祝您生活愉快，工作顺利，万事如意！ 这篇，是中国（）特地为大家整理的牛津版小学六年级英语期末考试卷，供广大师生学习参考! 一.下面每组单词中有一个是不同类的，请选出来，把序号填在题前括号内。 、busc、subwayD、plane 二.看图选句子。 ’s9:’stimeformathclass. ’sverykind. 三、单项选择。 ’m_____thanyou. ______youdolas tweekend? ___________? 5.______yourmotherlike? ’’’s ________forbreakfastthismorning? _______forus. _______greenapple. _______houseworkonSundays?
________uplatethismorning. _______somemeatonplate. ’ ，please? ;;;;at ;;;;have 四.情景交际。 1)你想约你的朋友周末去滑冰，你可以说： ’sgofishingthisweekend. ’sgohikingthisweekend. ’sgoice-skatingthisweekend. 2)当别人跟你说：mayIborrowyourdictionary?你回答说： ，’thinkso. 3)当你想了解某个物品的颜色时，你可以问： ’sthis??’syourname? 4)当你想问别人邮局在哪时，你应先说： ’ 5)当有人对你说Happybirthdaytoyou!时，你应说： 五.手拉手，找朋友从方框中找答语并把序号填在题前括号内。 六.根据对话内容，补充对话。把答案的编号写在
2019-2020九年级第二学期初三英语练习 一、单项选择 1. Dr. Zhong Nanshan, ________ 84-year-old man with gray hair, has been one of _______ greatest persons in my mind in the past three months. A. a; an B. a; the C. an; the D. the; a 2. My cousin Lisa is going to get married_______ John on New Year’s Day. They’re both______ their twenties. A. to; in B. with; in C. to; at D. with; at 3 ---Is David coming to your birthday party this evening? ---No, he _______ be at the party. He _______ to Shanghai on business. A.mustn’t; has gone B. mustn’t; has been C. can’t; has gone D. can’t; has been 4. ---Dad, _______ of the apples _______ gone bad. ---Well , we’d better eat up the rest as soon as possible. A. two-fifth; have B. two-fifths; have C. two-fifths, has D. two-fifth, has 5. _______ news! Our class will go to Beijing for a _______ trip this spring. A. What exciting; three-day B. What an excited; three days C. What an exciting; three-day D. What excited; three days’ 6. We found him __________ with. He’s quite an easy-going guy. A. easily to work B. easily working C. easy to work D. easy working 7. —Ted, how did you make Father’s Day special for your father? —Oh, we had _______and made a crown that I expressed my love for him. A. such interesting picnic B. so interesting a picnic C. so an interesting picnic D. such interesting a picnic 8. Nanjing isn’t so large_____ Shanghai, however, it’s the second ____city in East China. A. like; largest B. as ; largest C. like; large D. as; large 9. —How much difficulty did you have ______this problem? — ______. It’s quite easy. A. to solve; Nothing B. to solve; None C. solving; None D. solving; Nothing
九下Unit 6 单词短语归纳 1.实施，执行 v 1. 承受压力 2.争吵 n 2.集中于 3.集中（注意力、精力等）于v 3.解决，处理 4.压力 n with 5.是否 5.担心 6.风险 n 6. 防止，提防 7.守卫，保卫 7.抵消，对消 8.取消，撤退，终止 8. 忙于做某事 9.有希望的 9.把.....抛在后面 10.强迫，迫使（某人做某事） 10.使.....振奋起来 11.音乐会，演奏会 11.学着做，开始做 12.私人的 12.持乐观的态度 13.不说话的，沉默的 13. 抵消，对消 14.危害物，大敌 14.讲笑话 15.鼓励，鼓舞 15.去听音乐会 16.牙科医生 17.沮丧的，消沉的，无精打采的 adj 知识点 1.conduct v.实施；执行 n __________ 指挥家 Conduct a survey about a healthy conduct此处用作及物动词，意为“实施，执行”。 我决定去执行一个任务 _______________________________ n.争吵 have a quarrel with have a quarrel about 1)他刚刚和他的最好的朋友吵架了____________________________________ 2)他们为钱的事情吵架了 ______________________________________ 3.pleasure 不可数名词，________________ adj __________ Doing something for ________________. We are reading for _______________. 去滑冰是一件很令人愉快的事情 _____________________________________ my pleasure意为“不客气”，是对对方感谢的一种礼貌回答。
9B Unit 1 一掌握下面的短语和句型： (Comic strip and Welcome to the unit) 1.How do you like …? = What do you think of …? 你认为……怎么样？ 2.get to = reach = arrive in/ at 到达 3.think about 考虑 4.in the future 在将来 5.travel in space 太空旅行 6.try to do sth 尝试做某事，设法做某事，努 力做某事 7.dream about / of 梦见，梦到 https://www.doczj.com/doc/308288795.html,pare A to B = compare A with B 比较 A和B * compare A to B 把A比喻作B 9.care for 关心 * care for 照顾=take care of / look after 10.help sb with sth /help sb do sth 帮助某人做 某事 11.in the form of 以……的形状=in the shape of 12.make sb do sth 使某人做某事 (Reading) 1.find out 找到，找出 2.It is +形容词＋to do sth. 做某事是……。 3.more and more crowded 越来越拥挤 比较级＋and +比较级 “越来越……”4.spacecraft 宇宙飞船（单复数相同） ＝spaceship 5.first of all 首先 6.at present 目前 7.too … to … 太……而不能…… https://www.doczj.com/doc/308288795.html,rge numbers of 相当多…… a number of 很多……（谓语用复数） the number of ……的数量（谓语用单数）9.It takes sb some time to do sth. 花费某人多 少时间做某事。 =sb spend some time (in) doing sth. 10.at the speed of 以……的速度 He is traveling at the speed of 130 kilometers an hour. 11.three eighths 八分之三 分数：分子为基数词，分母为序数词，分 子多于1时，分母用复数。 one third 三分之一；two fifths 五分之二； a half 二分之一；a quarter 四分之一 12.prevent sb from doing sth 阻止某人做某事 ＝stop/keep sb from doing sth 13.in many ways 在很多方面 14.space 空间（不可数）＝room 15.take exams in online schools 在网上学校进 行考试 16.called = named 被叫作……的 =with the name of =that is called 17.as +原形＋as 和……一样…… 18.speed boots 加速靴子 19.make friends with 和……交朋友 20.many kinds of =many types of 很多种…… 21.under the control of 在……的控制下 22.tie sth to … 把某物拴在……上 We often tie our cows to the tree. 我们经常把牛拴在这棵树上。 (Vocabulary, Grammar) 1.take high-quality images 拍高质量的图象 take photos 拍照片 2.connect sth to … 把某物连接到……上 3.provide sth for sb. =provide sb with sth 给某 人提供某物 4.in that case 在那种情况下 5.take the place of 代替，取代 6.digital camera 数码相机 7.dried food 干粮，脱水食物 8.notebook computer 笔记本电脑 9.space sleeping bag 太空睡袋 10.the solar system 太阳系 11.be willing to do sth 愿意干某事 (Integrated skills and Study skills) 1.turn on 打开（电器、水龙头等） turn off 关闭（电器、水龙头等）