Test Of Stirring Dryer For Sewage Sludge With Superheated Steam And Design Of Double Shaft Paddle Mixing Dryer

With the vigorous development of the national economics and the advancement of urbanization construction, huge amount of sewage sludge has been generated as the number of urban sewage emissions become more and more big year by year. Sludge as a derivative of the sewage treatment process,which is a kind of contain pathogens, heavy metals, organic matter, and hazardous waste a lot of water. If not properly handle the outlet problem for the sludge will cause serious damage to the ecological environment and human health. Reducing the moisture content of sludge is the premise of effectively disposal of sludge, and thermal drying is one of the effective ways to reduce the moisture content of sludge. Traditional sludge drying equipment has the disadvantages of high energy consumption, low thermal efficiency, high pollution and so on, and the paddle dryer is a kind of high efficiency and energy saving drying equipment, especially suitable for high humidity of viscous sludge drying.With superheated steam as the medium of the sludge paddle agitation drying, could further strengthen the sludge drying effect. To study the effect of dry sludge in paddle dryer in the sludge, superheated steam drying test was carried out on the existing single shaft paddle dryer. Influence of superheated steam temperature and spindle speed for sludge drying effect, the results showed that: when the rotating speed of 500 r/min, the moisture content of sludge with the rising of superheated steam temperature was reduced, and the granularity of the sludge were becoming ever more obvious; When the superheated steam temperature of 280 ℃, the lower the spindle speed, the lower the moisture content of the sludge, the smaller the sludge particles. It was also found that there were some defects such as large dead angle, unreasonable arrangement of blades, poor sealing performance and so on, and the corresponding improvement measures were put forward.I designed the biaxial blade dryer Base on the single axis stirring drying experiment and sludge drying characteristics of superheated steam superheated steam. Firstly, according to the basic parameters and design requirements of sludge drying, the overall structure of the double shaft blade dryer was designed. Secondly, on the basis of the overall structure design, the key components of the mixing shaft, the blade, the sealing device, the upper cover and the transmission device were designed. Finally, through the theoretical research and calculation, the structure and technical parameters of the blade dryer were optimized and analyzed, This mainly includes: The mixing shaft adopts the structure of "three parts welding", and the shaft is checked; The phase angle of 90 degree was selected as the single axis stirring arm, mixing arms with doublepositive-inerlaced disscussive arrangements were recommended; the blade adopts 15 degrees, 20 degrees and 45 degrees in combination.In order to improve the thermal efficiency of superheated steam drying, the low energy consumption and zero pollution of sludge drying process are realized, on the basis of the twin shaft paddle dryer, a complete set of sludge superheated steam paddle drying system was designed. The technological process of the drying system was described in detail, and the total heat and mass balance of the sludge drying process was also analysed. And the selection and design of the steam generator, the feeding device and the heating device of the drying system were carried out.