The Research Of Performance On Biogas Cogeneration And Internal Combustion Engine Combined With ORC System

In order to realize the energy cascade utilization, further improve the thermal efficiency of biogas internal conbusion engine(ICE), a case of the biogas power generation plant at the Holstein cow breeding center of H ua Zhuang, Lan Zhou was studied which including the elaboration, key parameters calculation, performance study, and suggestions for the problems in system operation. For the sake of utilizing the exhaust heat of biogas engine, proposing a organic rankine cycle to recover exhaust waste heat for the cogeneration system. Established internal combustion engine model and organic rankine cycle model in different simulation environment, and analysis the performance of the combined system. The main results are as follows:(1)The paper introduced the current situation of the world’s energy, stressed out the advantages and existing problems of distributed energy supply system, pointed out the fact that there are large amount of renewable energy but the utilization efficiency is especially low, stated world resea rch status of distributed energy supply system with traditional energy and renewable energy respectively, elaborated and summarized waste heat recovery technology—ORC technology, and proposed renewable energy applications in distributed power supply system, and further pointed out how existing mature technology and urgent energy demand of users is linked.(2)Take the biogas power generation project at the Holstein cow breeding center of Hua Zhuang, Lan Zhou as study example, by monitoring recorded data, ana lysed and calculated the energy of the cogeneration system, it turned out that average daily biogas yield is 1200m3 in summer and 700m3 in winter respectively, and the design objective of the project in summer is achieved, average daily electric energy production is 1681 k W·h, generating efficiency is about 30%, waste heat recovery efficiency is 46%, so total energy utilization rate is as high as 76%. Than analyzed the operational benefits of biogas cogeneration system. In 2015: total biogas production is 210700m3,power generation is 316050 k W·h, standard coal saving is 126.4t, carbon dioxide reduction is 315 t, emissions of sulfur decreased at the same time, energy efficiency, economic and environmental benefit is significant. Study of the farm cogeneration system has very important significance for the construction in cold regions.(3)Simulation model of small power biogas engine was established with the software GT-power, the validity of the calculation model was verified by the experimental data through comparison, and on this basis, exhaust heat recovery system model was established with the software Aspen plus, calculated the combined small power biogas internal combustion engine and ORC system by simulation, sensitivity analysis was done of the key paramet ers of the combined system, and the conclusions are as follows: When operating conditions of the engine is at full load, the effective power, the thermal efficiency, exhaust temperature and flow rate of the engine all significantly increase with methane vo lume fraction of the biogas increases, therefore, purified or higher methane volume fraction of the biogas should be used as the fuel; When under conditions of different methane volume fraction of the biogas, net work of ORC increases with the organic work ing fluid flow rate increases, then decreases with the organic working fluid flow rate increases, so there is an optimum value, this provides an important reference for selecting mass flow rate of organic fluid under different conditions in the practical a pplication; With methane volume fraction increases, the ORC output power increases correspondingly, as high as 3.4k W, exhaust waste heat utilization factor is 64.8%, the efficiency of combined cycle power system increases by 7.6% than the conventional inte rnal combustion engine power system.The innovation point of this article :A combined small internal conbusion engine with biogas as fuel and organic rankine cycle is proposed, studying the performance of combined system by numerical simulation method.