沼气内燃机烟气余热ORC热电联产系统研究

Study on flue gas cogeneration system of biogas internal combustion engine based on ORC

以青岛市某污水处理厂为例分析了该厂现有沼气热电联产系统存在能源利用率及[火用]效率低的问题,并提出了内燃机烟气余热+ORC热电联产的余热利用方式。通过对改进后系统经济性、环保性及热工性进行计算分析,得到改进后的系统在满足污水厂中温厌氧发酵需热量的前提下全年发电量可增加60.2万kW·h,预计2.67年可收回初投资成本,相比较燃煤发电每年可节约200 t标煤,年CO_(2)、SO_(2)、NO_(2)以及烟气减排量分别为134 t、3.3 t、3.12 t、1.92 t,同时能源利用率及[火用]效率均有所提升。

Taking a sewage treatment plant in Qingdao as an example, low energy utilization and exergy efficiency problems existing in the biogas cogeneration system were analyzed, the waste heat utilization mode of internal combustion engine flue gas waste heat+Organic Rankine Cycle(ORC)cogeneration was put forward.Through the calculation and analysis of the economy, environmental protection and thermal performance of the improved system, it is obtained that the annual power generation of the improved system can be increased by 602 000 kW·h on the premise of meeting the heat demand of medium temperature anaerobic fermentation in the sewage plant, and the initial investment cost is expected to be recovered in 2.67 years.Compared with coalfired power generation, it can save 200 tons of standard coal.The annual CO_(2), SO_(2),NO_(2) and flue gas emission reductions are 134 t, 3.3 t, 3.12 t, 1.92 t respectively.At the same time, energy utilization and exergy efficiency have been improved.