Study On Atomization And Dry Process Of The Sludge

With the acceleration of urbanization and sewage treatment rate, the large numberof sludge has become an important factor restricting urban development. Sludgetreatments have many ways in the current, but because it will bring serious secondarypollution, are not widely used. Cement kiln co-processing of sludge technologyprovides a new way of thinking for the disposal of sludge, with that other technologiesdo not have the advantage, is expected to solve the problem of secondary pollution,which is the key to achieve low-temperature drying wet sludge. The subject makesfull use of the cement kiln system equipment and conditions, to achievelow-temperature drying of sludge for cement kilns co-disposal of sludge technologydevelopment by atomization dry.In this paper, it studied the atomization of sludge by high-speed photographytechnique and the atomizing effect of different operating parameters, also studied thesludge drying process gas release conditions from the sludge composition and structure,carried out semi-industrial tests in the semi-industrial test systems. The study resultsshowed that:It recorded the sludge atomization process and revealing the essence ofatomization by using high-speed photography. Atomization process actually is theprocess that sludge floc constantly being torn smaller. In this process, the sludge is cutlayers; floc structure is destroyed, while the inorganic particles separated from thesludge.It analyses that operating parameters effect on sludge atomizing. As the atomizinggas flow rate increases, the spray angle increases and the atomization effect is good.The spray angle is no longer increases with the flow rate and the best dispersion ofsludge at177.4m/s and0.646MPa. The sludge drying results showed that: sludge free water accounted for77.5%,and16.7%capillary water. Drying process, with the evaporation of water, sludgevolume shrinking, the sludge was observed under an optical microscope crackingprocess, found that when the mud layer thickness is0.4mm, the sludge was crackingtype, mud layer thinning, cracking tend to be evenly split.Thermo gravimetric analysis showed that: dried sludge have the maximum rateof gas evolution at273.75℃³33.76℃the temperature range in the heating process;sludge gases released during the heating process are mainly CO₂, H₂O, NH₃, VFA andthe chain alkenes, which VFA at333.76℃previously released completely, chainalkanet emission maximum at333.76℃.Semi-industrial tests showed that: the atomized sludge drying instantaneouslycompleted at200℃temperature. Drying sludgeforms mainly is granular and flake,after drying sludge moisture content was38.7%. It can be achieved through a screwconveyor in after mixing with cement raw material. The flue gas of volume180000Nm³/h can dry252t/d sludge which moisture content was84.5through theheat balance calculation into the hot flue gas conditioning tower temperature of260℃.Results of this study for the cement kiln system provides the basis of data forindustrial application of sludge disposal technology...