Energy efficiency analysis of integrated coupling between circulating fluidized bed boiler generator unit and garbage and sewage treatment

LI Jianfeng; ZHANG Shaojie; ZHOU Ziyuan; MA Qianqian

doi:10.13225/j.cnki.jccs.DC25.0027

Abstract：In order to reduce CO2 emissions and water consumption in coal-fired power generation,improve the effi-ciency of waste-to-energy incineration,and enhance the speed and efficiency of biological wastewater treatment,a coupled system integrating waste and sewage treatment with circulating fluidized bed power units is proposed.Specifically,anaer-obic fermentation,domestic and industrial wastewater treatment systems are constructed alongside the circulating fluid-ized bed boiler units.The anaerobic fermentation system is designed to handle waste from the food industry,agriculture,and livestock sectors,while the domestic and industrial wastewater treatment systems treat sewage and industrial wastewa-ter respectively.The heat required for fermentation and wastewater treatment is sourced from low-pressure steam extrac-tion or exhaust waste heat from turbines.The biogas produced from fermentation is coupled with coal-fired power genera-tion,while the sludge is used to produce organic fertilizers.Domestic sludge can be co-fired with coal in the fluidized bed boiler,and industrial sludge can be either co-fired or treated for harmlessness based on its composition.Combustible waste unsuitable for fermentation is preprocessed and directly fed into the fluidized bed boiler for co-firing with coal.A case study was conducted on a 2×350 MW supercritical circulating fluidized bed unit coupled with waste incineration and wastewater treatment systems.Energy efficiency calculations,application scenarios,and benefit analyses were performed.The results indicate that for a city with a population of 1 million,annual waste-to-energy incineration can reduce standard coal consumption by 115 900-193 200 t and CO2 emissions by 308 300-513 900 t.In terms of biogas utilization,it can be directly co-fired with coal in the furnace for power generation,or coupled with gas turbines and coal-fired units through flue gas or steam integration.As the gas turbine capacity increases,the power generation efficiency of the coupled system continues to improve.Under the same conditions,flue gas coupling yields higher efficiency than steam coupling.The coupled system also offers additional benefits such as water conservation,reduced construction costs for fermentation fa-cilities,land and total investment savings,and eligibility for financial subsidies.In summary,the integration of circulating fluidized bed units with waste incineration and wastewater treatment systems delivers significant environmental and social benefits.Although this approach may face practical challenges such as cross-industry and cross-departmental coordination,it remains worthy of further research,particularly in the planning and development of new urban areas,where it holds greater implementation potential.