Analysis And Optimization Of Environmental Impact Of Distributed Energy In Building Clusters Under The Background Of "Double Carbon"

Under the background of accelerating the transformation of global energy structure,the form of China’s energy system has accelerated the transformation,showing the characteristics of dispersion,flat and low-carbon.It is clear that the development goal of carbon peak and carbon neutralization is proposed to promote the electrification and low-carbon of building energy,actively develop distributed energy and build a clean,low-carbon,safe and efficient energy system.However,at present,the gas distributed energy system has some practical problems,such as poor matching between supply and demand,system energy efficiency lower than the design value,high emission and so on.The gas distributed energy CCHP system has failed to give full play to its advantages in cascade utilization,comprehensive efficiency,energy conservation and emission reduction.In this context,in order to analyze the matching between supply and demand of gas-fired distributed energy,this paper first puts forward different prediction methods in stages,such as Monte Carlo peak load analysis in the planning stage,uncertain quantitative long-term load analysis in the design stage,SVM and PSO-BP short-term load analysis in the operation stage,and establishes multi-stage load models and data based on the case objects of each typical office,commercial and hotel complex of more than 20000 square meters.The results show that the relative error of the maximum cooling load obtained by Monte Carlo simulation method is22.6%,which is lower than 67.9% in the feasibility study report.The long-term deviation rate of commercial load index calculation and uncertainty quantification,which are relatively sensitive to external conditions,is 61%.Using a single index method to calculate the load is easy to cause a large deviation from the actual load.The PSO-BP algorithm and GA-SVM algorithm in the operation stage are in good agreement with the actual load,and the maximum relative deviations are 12.8% and6.4% respectively.GA-SVM algorithm can obtain higher prediction accuracy.Thirdly,in order to analyze the low efficiency of gas distributed energy system,this paper establishes the distributed energy index and mathematical model of building group,and puts forward the fast non dominated sorting genetic algorithm NSGA-II with elite strategy.Taking the 4.4mw distributed energy of large building group and the distributed energy of 315 KW gas internal combustion engine as the modeling object,considering the power balance constraints of electricity,heat and cooling and the operation characteristic constraints of equipment,The best trade-off optimal solution is quickly selected through Pareto frontier.The results show that the multi-objective optimization operation of gas distributed energy combined with waste heat utilization and ice storage system has greatly improved the system operation utilization rate,supply and demand matching and economy.Under the condition of large and stable cooling load demand,the benefit of internal combustion engine + lithium bromide is 9.2% higher than that of internal combustion engine +lithium bromide + water cooler,but the cooling load of internal combustion engine and lithium bromide series air conditioner under 20000 low cooling load demand exceeds the actual value by about 65%.Finally,in view of the unsatisfactory effect of energy conservation and emission reduction of gas-fired distributed energy system,this paper analyzes the impact of gas-fired distributed energy on the regional environment,establishes the evaluation models of comprehensive energy utilization rate,CO2 emission reduction rate and annual energy-saving rate,takes the building group distributed energy supply system as the case study object,and puts forward the influence relationship between the efficiency and emission of gas-fired internal combustion engine,as well as the optimization method of urea SCR to reduce emissions.The results show that under the same load,the primary energy utilization rate of internal combustion engine +lithium bromide energy supply system is 84.13%,which is higher than that of micro combustion engine + lithium bromide energy supply system by 81.92%;For the same type of internal combustion engine,its efficiency and emission show a certain law.Under 100% load,the energy utilization efficiency of No.1 internal combustion engine is 88.36%,which is higher than 87.33% of No.3 internal combustion engine.However,the exhaust energy of No.3 internal combustion engine is 6367.59 kw,which is lower than 6605.16 kw of No.1 internal combustion engine.There is the most ideal operation state under specific environmental requirements.Through the simulation analysis of urea SCR emission from internal combustion engine,the inlet velocity uniformity of the first layer catalyst is improved after the porous plate is arranged.The relative deviation coefficient of 10.5% at the inlet velocity of 4.1m/s is lower than that of 23.1% at the inlet velocity of 5.66m/s,but under the same injection position,the reductant uniformity at the inlet velocity of 5.66m/s is better than that at the inlet velocity of 4.1m/s.