基于过热蒸汽干燥开式制粉燃褐煤发电技术研究

An efficient lignite-fired power generation process based on a super-heated-steam-dried open pulverizing system

针对高水分褐煤燃烧发电中存在的热效率低和低负荷稳燃困难等问题,提出了基于过热蒸汽干燥开式制粉系统的新型高效燃褐煤发电技术,该技术采用基于汽轮机抽汽加热的过热蒸汽干燥开式制粉系统,保证了制粉系统的运行安全性,提高了燃烧系统的运行灵活性,实现了制粉系统与锅炉主机的运行解耦,并综合解决了褐煤锅炉炉温低、热效率低的等问题。以600 MW超临界燃褐煤机组为例,对采用该技术的热力系统进行了仿真,分析了其节能与环保效益。研究结果表明,该技术通过对锅炉与汽轮机整体热力系统的综合优化,将汽轮机回热系统扩大至高水分煤的干燥过程,同时梯级回收锅炉排烟废热和制粉乏汽废热至汽轮机回热系统,可获得较为显著的节煤效益。同时,该技术不仅可由节煤相应减少各类污染物及CO_(2)排放,还可回收大量水资源,有望实现零水耗电厂。

To solve the problems of low thermal efficiency and unstable low-load combustion of lignite-fired power units,a new efficient lignite-fired power generation technology is proposed in this paper based on using a superheated-steam-dried open pulverizing system.This technology adopts a superheated-steam-dried open pulverizing system in which the heat of steam extraction is used for drying raw coal,which ensures the operation safety of the pulverizing system,improves the operation flexibility of the combustion system,realizes the decoupling of the pulverizing system and the boiler,and comprehensively solves the deficiencies of the lignite-fired boiler in terms of low furnace temperature and low thermal efficiency.Taking a 600 MW supercritical lignite-fired power unit as the case,the thermal system using this technology was simulated and analyzed for its thermo-economic environmental benefits.The results show that the technology can obtain significant coal savings by comprehensively optimizing the thermal system of boiler and turbine,expanding the turbine regenerative system to the drying process of high-moisture coal,and at the same time recovering the waste heat of boiler flue gas and exhausted steam into the turbine regenerative system in a graded heat recovery manner.Moreover,this technology not only reduces all kinds of pollutants and CO_( 2) emissions accordingly from coal saving,but also recovers a large amount of water resources,which is expected to realize a zero-water-consumption power plant.