497 / 2018-12-31 12:51:40

Concept study of a biomass-fired CHP system based on supercritical carbon dioxide cycle

biomass energy; combined heat and power generation; supercritical carbon dioxide cycle; efficiency

全体主题 > 节能、联产、热泵

Combined heat and power (CHP) generation is one of the main forms of large-scale utilization of biomass energy, which has high energy efficiency and good economic and social benefits. As a distributed energy source, the comprehensive performance of biomass CHP system is closely related to the energy conversion technology adopted. Combination of biomass direct combustion and power cycle is a widely used technology route at present. The biomass-fired power generation technology based on steam turbine unit is very mature and has good performance. In order to further optimize biomass-fired CHP technology, the concept of CHP system based on supercritical carbon dioxide cycle is proposed in this paper. The heat capacity and combustion temperature of biomass-fired boilers are very suitable for supercritical carbon dioxide cycle. The CHP system composed of the two are efficient, simple, and easy to operate and maintain. In view of the current situation in northern China, the heating period is 4 to 7 months. As a distributed energy source, the above CHP system can be equipped with a boiler of 3 to 10 MWth capacity, and it can be divided into two operation modes: CHP mode and pure power generation mode, which are used in heating season and non-heating season respectively. The CHP model adopts a simple Brayton cycle, and the heat released from the cold end is used for heating. The energy efficiency of the system can reach more than 85%. Pure power generation mode adopts splitting cycle mode, and the power generation efficiency of the system can reach more than 35%. From the point of view of the equipment composition of the system, as compared with the steam turbine unit, supercritical carbon dioxide cycle removes chemical water treatment equipments, reduces the volume of the turbine and has no pump, but adds the compressors, the number of heat exchangers is almost equal, and boiler and other equipments remain unchanged. Overall, the equipment investment and operation cost of CHP system based on supercritical carbon dioxide cycle will be reduced. The conceptual study shows that the CHP system based on supercritical carbon dioxide cycle has potential value for practical application.