Study On Movement Of Msw In Rotary Kiln Cold Simulator

The generation of municipal solid waste(MSW)has increased gradually with the improvement of economic and living standards of people.It is projected that by 2020 200 million tons/year will be produced.The pyrolysis technology for MSW,compared with incineration,has a higher WTE(Waste to Energy)rate,lower second-step pollution and are suitable for small scale operation.It has been considered a more suitable MSW treatment technology in small towns.The rotary kiln is the most widely used MSW pyrolysis reactor,however the effect of rotary kiln rotational speed and slope on MSW mean residence time(MRT)and mixing rate is not yet clear.In this study a laboratory-scale rotary kiln cold simulator was developed.Self-made MSW,MSW pyrolysis bio-char and quartz sand were selected as the testing material in order to investigate the MRT,MVF(material volumetric flow)and mixing rate of solid materials.The MRT model of MSW and bio-char was developed using the single particle trajectory model and write a calculation sheet for equipment of 10 kg/h MSW rotary kiln pyrolysis and bio-char incineration.From the orthogonal experimental we concluded that rotational rate and kiln slope are the main influencing factors that affect pyrolysis of MSW and bio-char..Results showed that MRT is inversely proportional to rotating speed and kiln slope.The internal structures increase the mixing degree significantly and MRT as well.Increasing the rotational speed of rotary kiln and the laying of the internal structure improved the transverse mixing rate of tracer particles.The longtitudinal mixing rate of materials was also increased with the increase of rotational speed and kiln slope.For MSW,the effect of different internal structure on the longtitudinal mixing rate is not remarkable.For bio-char,under the same internal structure,the longtitudinal mixing rate of clockwise was bigger than that of counterclockwise.With the movement of material in rotary kiln,the longitudinal diffusion variance presents obvious rising trend,which indicates that the dispersion degree increases with the operation of the rotary kiln.Complete mixing timec decrease with the increase of rotational speed and increase with the increase of bed height.The complete mixing time changed slightly with the increase of inside wall roughness.The equipment which was built in this paper concludes the size mached rotary kiln and combustion chamber.The results of this study can provide guidance and improvement of MSW rotary kiln pyrolysis,specifically,laying the ground for the design for the industrial scale.