Thermodynamic and environmental evaluation of biomass and coal co-fuelled gasification chemical looping combustion with CO2 capture for combined cooling, heating and power production
2017
Fan, Junming | Hong, Hui | Zhu, Lin | Jiang, Qiongqiong | Jin, Hongguang
This work presents a detailed investigation of biomass and coal co-fuelled gasification chemical looping combustion for combined cooling, heating and power (BCCLC-CCHP) generation system from both thermodynamic and environmental aspects. Addition of biomass (corn stover) as blending fuel not only provides possibility of utilizing renewable energy, but also greatly reduces greenhouse gas emissions. The application of chemical looping combustion for oxidation of syngas is aimed at inherent separation of CO2 without extra energy penalty. At based design conditions, the energy efficiency and exergy efficiency can reach 60.16% and 22.16% in summer, respectively. Three key parameters, namely oxygen to carbon ratio (O/C), operating temperature of air reactor in the chemical looping combustion and share of corn, are considered to analyze their influences on system performances. O/C ratio is not sensitive to energy output, however an optimum value of O/C=0.42 is found to obtain maximum system efficiency and primary energy saving ratio (PESR). Increasing AR operating temperature benefits power generation but lowers down cooling and heating production. Increasing corn mass share from absence to 50wt.% to replace part of coal results in energy efficiency losses by approximately 6 point percentages but the PESR is increased by up to 5 point percentages. Capture of photosynthetically-derived CO2 (from corn) by CLC offers negatively cradle-to-grave greenhouse gas emissions in the BCCLC-CCHP process when corn mass share is higher than 15%.
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