A waste heat cascade utilization system and method for supercritical water oxidation sludge treatment

Abstract

The invention discloses a gradient utilization system and method for waste heat generated during treatment of supercritical water oxidation (SCWO) sludge, and belongs to the technical fields of chemical industry and environment protection. The method comprises the following steps: heating sludge for thermal hydrolysis through a thermal hydrolysis reactor; performing first-stage preheating on the sludge through a sludge preheating tank; making the sludge release heat in an SCWO reaction by taking an SCWO technology as a core to become high-temperature thermal fluid; performing high-temperaturesegment preheating on the material to a supercritical condition through a high-temperature preheater, a reboiler, the thermal hydrolysis reactor and the sludge preheating tank in sequence; re-boilingthe deaminized fluid through the reboiler to generate steam for subsequent ammonia stilling; recycling the waste heat of the high-pressure fluid with a waste heat refrigerating-heating unit; introducing the fluid into a deaminizing unit for further performing ammonia nitrogen treatment after the fluid flows through a depressurizing-separating unit; finally recycling the waste heat of the low-pressure fluid through a waste heat heating unit to realize harmless treatment of the sludge and efficient utilization of system energy. By adopting the gradient utilization system and method, the runningcost is lowered effectively, and the economic performance of the system is improved.

Description

technical field [0001] The invention belongs to the technical fields of chemical industry and environmental protection, and in particular relates to a waste heat cascade utilization system and method for supercritical water oxidation sludge treatment. Background technique [0002] With the rapid development of my country's urban population and urbanization process, the output of urban sewage is increasing, and the number, treatment capacity and sludge production of sewage treatment plants are also increasing. Every 10,000 tons of sewage is treated to produce an average of 2.6 tons of wet sludge with a moisture content of 80%. In 2016, the sludge production has exceeded 40 million tons. It can be seen that the output of municipal sludge has increased year by year, and the growth rate is obvious. However, the harmless rate of municipal sludge is still less than 25%, which has not reached the planned 80% rate of sludge treatment and disposal. Taking Beijing as an example, as ...

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Problems solved by technology

[0010] At present, there is no system and method for preheating cascade utilization specifically for supercritical water oxidation sludge treatment

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