Study On Construction And Performance Of Cogeneration System Of Heat Power Biogas And Biogas Fertilizer For Rural Single Buildings In Clusters

With the proposal of the national goal of"carbon peaking and carbon neutralization",it is imperative to improve the proportion of renewable energy in the energy consumption structure.However,in China’s rural areas,due to the limitations of geographical location and scientific and technological level,renewable energy is used improperly and inefficiently,and fossil energy still plays a major role in the energy consumption structure,which has caused serious harm to environmental protection and human health.Therefore,this thesis takes the village composed of 100 typical single buildings in northwest new rural areas in Yuzhong County,Lanzhou City,Gansu Province as the object,a cogeneration system of heat,power,biogas and marsh fertilizer composed of single building photovoltaic photothermal integration device,dual-source heat pump and biogas cogeneration is constructed.Then,compared with the traditional rural energy consumption system composed of firewood cooking,coal-fired heating and traditional electricity,the mathematical model,evaluation index and an optimization model of the system are established.Finally,the multi-objective optimization analysis of the system performance is carried out based on Python3.8,in order to meet the energy needs of users,and realize the efficient recycling of renewable resources and the protection of ecological environment in rural areas.The main conclusions are as follows:（1）The hourly annual heating load,electricity load and domestic hot water load of users are simulated by DeST software.By calculation,the average heating load during heating period is 36.7W/m²,the annual household electricity load is 4.56kW·h/d,and the household hot water load is 6.07kW·h/d.In addition,the biogas potential of village biomass（crop straw,vegetable waste,organic waste and manure）was evaluated.After evaluation,biogas production of biomass resources in this village is 194.6m³/d,which meets the biogas load of users.The cogeneration of surplus biogas can also meet 41.49%of the electricity load of users.（2）Taking the optimal economy,energy saving,environmental protection and comprehensive evaluation index as the objective functions,the improved particle swarm optimization algorithm with adaptive inertia weight is used to optimize the system equipment capacity.The optimization results with the optimal comprehensive evaluation index as the objective function are 65kW biogas generator,19.56m² photovoltaic photothermal integration component per household,and the objective function value is 42.80%.In addition,by comparing and analyzing different optimization results,it is found that the change of biogas generator capacity has a more obvious impact on the economy and comprehensive evaluation indicators of the system than the change of photovoltaic-photothermal integration component area;both changes have a weak impact on the environment protection of the system and a greater impact on the economy;the reduction of biogas generator capacity and the increase of photovoltaic photothermal integration module area will reduce the comprehensive evaluation index of the system.（3）In order to better understand the annual operation performance of the system,taking the optimization result of the optimal comprehensive evaluation index as the objective function as an example:a)In the annual input energy of the system,solar energy,biomass energy and air energy account for 36.99%,56.91%and 6.09%respectively;in the annual output energy of the system,thermal energy,electric energy and biogas energy account for 15.32%,3.54%and9.92%of the total input energy of the system respectively,of which the on grid power accounts for 1.44%of the total input energy of the system and 15.30%of the total power generation of the system.b)Compared with the traditional rural energy consumption system,the annual cost saving rate of the system is 25.38%,the primary energy saving rate is 13.60%,the CO₂ emission reduction rate is 89.41%,and the annual CO₂ emission reduction is 6108.88t,the dynamic investment payback period is 6.07 years,and the net present value is 4,624,900 yuan within the equipment life cycle,indicating that the system is economically feasible.c)Among the technical and economic parameters that affect the performance of the system,the change of the biogas stove thermal efficiency,the price of photovoltaic photothermal integration component,the price of anaerobic fermentation system and the price of biogas slurry should be paid more attention to.We can optimize the structure of biogas stove,select the component type and fermentation device with high energy utilization efficiency and low investment,and promote the utilization of biogas slurry to farmers near the system,so as to improve the energy saving,environment protection and economy of the system.The research results are of great significance to improve the rural energy consumption structure,improve the living standards of rural residents and promote the coordinated and sustainable development of energy,resources and environment in rural areas.