Drying Technology
Key words: waste heat, waste hot water,sludge drying
Whether it is industrial sludge or municipal sludge, a feasible purpose of its treatment is to be returned to the process as raw materials. At present, the state has issued a number of policies to encourage sludge reduction, stabilization, harmlessness, and resource utilization. Reducing the water content of sludge is a way to reduce it, and it is also a prerequisite for resource utilization of sludge, so sludge drying technology is vigorously promoted in China. 
Sludge drying technology is a process of net energy expenditure, and the proportion of energy consumption in the operating cost of the system is greater than 80%. Therefore, the development of energy-saving and low-carbon sludge drying technology has important practical significance. Solar energy, industrial waste heat, waste hot water, etc. as the heat medium for sludge drying will be the future technology development trend.
Low temperature drying: In the process of sludge drying, the volatile matter in the sludge will escape (VOC) when it exceeds 250°C, resulting in a decrease in calorific value. When it exceeds 60°C, ammonia will volatilize and cause damage to the sludge drying equipment. A certain degree of corrosion. Low-temperature drying only consumes electric energy and does not require other auxiliary energy sources, and the energy consumption is 1/3 of conventional drying equipment. The entire drying temperature is controlled within 60°C. No external heating equipment is required during the drying process. Low-temperature drying It can reduce energy consumption while effectively reducing malodorous gas emissions. Due to the low temperature, the volatilization loss of organic matter in the sludge is small, and the contribution of calorific value is high. In the future, low-temperature dryers will use waste hot water, low-pressure steam, solar energy, and flue gas as auxiliary energy sources, which will not only further save energy, but also conform to the national energy policy, which will be a technological development trend.
