Drying Technology
Keywords: Wastewater treatment、Sludgedryer
With the rapid development of the city, the number of sewage treatment plants and sewage treatment capacity increase simultaneously, leading to a rapid increase in the amount of sludge. In the past, concentrated sludge was only treated to 80% water content by mechanical dehydration before relevant disposal.
Whether it can be used on a large scale depends largely on the characteristics of the sludge, such as its chemical composition, treatment and disposal, such as dehydration, digestion, drying and incineration. Sludge characteristics are also related to drainage system, living habits, natural climate and treatment process. In order to determine the appropriate sludge treatment process, it is necessary to understand the current sludge composition and predict the future sludge composition to achieve better treatment effect.
In sewage sludge incineration, the drier the sludge is, the less water it contains, and the more suitable for incineration. Due to the different water content of sludge, different incinerators should be used. For example, when treating completely dry powder sludge and granular sludge with a certain water content, different incinerators with different furnace convection parts and loading equipment should be used. Therefore, how to dry sludge and determine its water content to minimize energy consumption has become increasingly important. The analysis of different schemes shows that drying the sludge to a moisture content of less than 50% before incineration is more economical and safer with less energy consumption. The energy required to dry the sludge to 50% moisture is more than that required to dry the sludge
Drying to 10% moisture requires much less energy. Granular sludge will not be suspended in the air, which reduces the possibility of dust explosion and greatly increases the safety.
The remaining sludge is pumped from the treatment plant to the concentration treatment plant, where it is concentrated and treated with additives according to the water content, sludge characteristics and final disposal requirements. The thickened and cooled sludge is then pumped into the membrane plate and frame filter press by the sludge pump and pressed into a sludge cake with moderate hardness. Then filter the sludge cake to produce soft and hard sludge cake. The sludge cake is conveyed to the sludge dryer by the plate and frame filter press in a precisely specified quantity through the conveyor. Sludge dryer is the main drying point of sludge. The low temperature hot air from the heating system directly contacts with the internal sludge to remove the moisture in the sludge, thus drying the sludge.
