Energy saving and carbon reduction production process of municipal sludge-based biochar: Optimization, simulation, and techno-economic analysis

The production process of municipal sludge-based biochar is a promising and efficient sludge treatment process. However, inefficient cleaner production and limited resource utilization always caused environmental and cost concerns. Based on the measured data of engineering field operation, the optimized production process of energy saving and carbon reduction is put forward by using the process simulation of Aspen Plus software and economic analysis approach, and the sludge treatment capacity is 300 t/d. The objective of the study is to comparatively evaluate the energy efficiency, carbon emission reduction efficiency, and techno-economic performance of the optimized process. The newly added SNCR and low-temperature SCR units are combined denitration and coupled with a waste heat recovery unit to reduce energy consumption. Meanwhile, reduce carbon emissions and NOx emissions in the whole process. The base case of the optimization process and resource utilization was found to be viable. Compared with the conventional process, the energy efficiency is increased by 8.52%, the total carbon emission is reduced by 27.41%, and the total emissions of NOx and SO2 emissions are reduced by 78.11%, thus reducing the environmental burden of greenhouse gas emissions. The total product cost is reduced by 26.76%, the annual investment rate of return is increased by 27.45%, the gross profit rate is increased by 23.78%, and the internal rate of return is increased by 45.19%, which has excellent profitability.