基于化学回热的沼气冷热电联供系统

A Biogas CCHP System Based on Chemical Regeneration of Heat

为了实现沼气化学能和物理能综合梯级利用,提出一种基于化学回热的沼气冷热电联供系统。新系统引入重整器,利用透平高温排气驱动沼气重整,生成具有更高化学能的合成气,以提升沼气燃烧前热值。利用Aspen plus软件进行仿真模拟,模拟结果表明:通过沼气重整可使沼气转化为化学能更高的合成气,同时可回收大量低温潜热用于沼气池保温。在设计点工况下,新系统㶲效率较参比系统提升了21.88%~31.25%。通过参数分析可知,水蒸气与沼气摩尔比(水碳比)对系统性能影响较大,当水碳比从0.5提升到4.8时,甲烷转换率从0.12增大至0.48,提高了余热回收利用。燃气轮机输入热值的提高使得新系统发电量从13.37%提升到55.55%,最终使得系统的㶲效率从9.68%增大至41.94%。

In order to realize the comprehensive cascade utilization of chemical and physical energy of biogas,a kind of biogas cold-heat-electricity combined supply system based on chemical reheating is proposed in this paper.Reformer is introduced into the system to drive biogas reforming by using high-temperature exhaust of the turbine to generate syngas with higher chemical energy to obtain more elevated calorific value before biogas combustion.The simulation results show that biogas can be converted into syngas with higher chemical energies by biogas reforming,and a large amount of low temperature latent heat can be recovered for biogas digester insulation.At the design point,the exergy efficiency of the new system is 21.88%-31.25%higher than that of the reference system.Through the parameter analysis,it can be seen that the molar ratio of water vapor to methane(water-carbon ratio)has a great influence on the system performance.When the water carbon ratio is increased from 0.5 to 4.8,the methane conversion rate increased from 0.12 to 0.48,which improved the utilization rate of waste heat recovery,and increase in the calorific value of gas turbine input makes the power generation advantage of the new system is increased from 13.37%to 55.55%,and finally the system efficiency is increased from 9.68%to 41.94%.