The Techno-economic And Emission Reduction Benefit Assessment Of Biomass Moving-bed Pyrolytic Polygeneration System Based On Aspen Plus

Biomass,as the unique renewable carbon resource,has gained more and more attention,which can be utilized to produce multiple fossil fuel alternatives.In the pyrolysis process,biomass can be thermally converted into bio-char,bio-oil and biogas,which contribute the greenhouse gas（GHG）emission reduction as the fuels substitution.Through investigating economic and environmental benefits of biomass thermochemical converting process,those development potential can be correctly recognized.Although there has been intensive studies on the one specific production chain,there is still lack of research on the assessment of product co-generation since it is under research stage.Thus,it is urgent to make the comprehensive analysis in terms of economic and environmental benefits.On the basis of biomass moving-bed pyrolytic polygeneration system with straw waste as raw material,this study analyzed the economic and GHG emission reduction benefits under different operating parameters,and investigated the environmental benefits deriving from the large-scale utilization of this system.Firstly,the comprehensive model is built that combines the raw material collection process,the Aspen Plus simulation,and the hybrid life cycle model in this research.Meanwhile,the life cycle boundaries is determined that include the crop production,collection transport,industrial production,and waste disposal processes.Based on the biomass pyrolysis mechanism and components pyrolysis property,the model of pyrolysis system was built on the Aspen Plus simulator,and the functional relationship between reaction temperature and industrial scale with economic and GHG emission reduction indicators were summarized.Then,on the basis of material and energy flow of simulation results of typical agricultural residue,the system economic benefits was assessed with net present value method and the process capital inventory.According to the pyrolysis products yield and property,the GHG emission reduction potential was investigated with national emission intensity data.Finally,combined the economic benefits with environmental benefits,their coupling relationship was studied,and the synergy effect of pollution emission reduction at large scale as well as GHG emission reduction benefit was discussed.Results indicate that the project can resist the economic risk when the specified capacity is over 5 ton per hour,and the system is the most economical when at 310°C and550°C.Meanwhile,the GHG emission intensity of this system is between 4.15⁶.12 g CO₂-eq/MJ,and it have the greatest benefit of reducing GHG emissions when at 250°C.Increasing the bio-char yield and the output of pyrolysis products are the keys to increasing the GHG emission reduction potential.Considering the economic and environmental benefits,the system optimum temperature is 310°C.The national scenario analysis based on product demand shows that the system can annually generate 8.08×10⁶ t CO₂-eq,2×10⁴t PM_2.5,and 1.28×10⁴ t NOx emissions reduction benefits,whose temperature is set at 410°C and there should be 214 pyrolytic plant to meet the products demand.Due to the limitations of pyrolysis products utilization,the consumption of biomass straw is 5.35 million tons per year for large-scale utilization of the system,which is much lower than the straw yield.Therefore,the system needs to focus on improving the quality of the liquid phase product and increasing the utilization approach,which can further improve the economic and environmental benefits of this system as well in turn.