Municipal Sewage Sludge For Dry Processing And Mixed Burning With Coal Experimental Study

In many sludge disposals, incineration is widely recognized as the most thorough reduction, stabilization and safe disposal. Current sludge drying exist Problem of incineration high running costs and complex process. The incineration cost reduction, simplification of the process has become critical sludge drying incineration process widely used. Low calorific value of dry sludge, separate incineration effect of instability, need to consume a large amount of auxiliary energy. Sewage sludge and coal in thermal power plants co-firing process, not only solved the problem of disposal of sludge and sludge utilization. This paper examines is sludge pretreatment-solar drying-blended burning with coal, as sludge industrialization disposal pathway feasibility.By adding the reagent and using the ultrasonic pretreatment for sludge, studies the influence of pretreatment on water content of sludge and dewatering performance. Using self-made the solar device as pretreatment process subsequent drying means, for Lu’an north of the city sewage treatment plant sludge pretreatment process brief introduction and record the operation of technical parameters, for continuous monitoring basic properties and heavy metals of the process output sludge. Compare Lu’an sludge (60%) and Hefei sludge (80%) under condition of different thickness on drying, the change of water content and drying rate changes. Examine the influence of sludge particle size and the thickness on sludge drying effect. Using incinerator burning test under the condition of sludge different moisture content (30%,40%,50%) and with coal in different mixing ratio (1:3,1:4,1:5), record the change of temperature, and detection of seven heavy metals content in the ash after burning. the determination of sludge and coal blending ratio and blending of sludge the best water content. Conduct a large number of industrial Co-combustion experiments, comparison with separate incineration of coal, analysis the stability of the furnace temperature, the amount of steam production of the raw coal and a secondary monitoring of polluting emissions, and to verify the feasibility of Co-combustion of the sludge and coal.Results showed that:Sludge pretreatment experiment showed drying rate increase distinctly after pretreatment,40KHZ ultrasonic frequency and power is150W; ultrasonic time3min is the best time. When chemical conditioning, composite reagent to improve sludge drying effect is the best, and chemical conditioning than ultrasonic pretreatment for sludge dewatering performance improvement is more obvious. The monitoring of pretreatment process output sludge found that the sludge moisture content fell to60%from88%, calorific value is reduced, heavy metal content by a certain decline, ash content increased. when solar drying experiments considering energy consumption and drying time, the same water content sludge thickness1cm and particle size1cm drying with the shortest time, drying rate under optimal conditions was2.13g/cm2·h. The sludge mixed burning experiment, the best blending proportion of sludge and coal is1:4, the best mixing burning the sludge moisture content of40%. After industrial Co-combustion, the sludge emissions of SO2, NOx, NO, Hcl when comparison with separate incineration of coal didn’t change much and is not beyond the limited standards of the state, and description sludge and coal blending is feasible.