超超临界1000 MW机组EC-BEST技术经济性分析

Economy analysis for an ultra supercritical 1 000 MW unit with EC-BEST thermal dynamic system

EC-BEST技术是为下一代700℃等级高超超临界发电技术提出的,将其应用于目前的600℃等级超超临界1 000 MW机组时是否具有经济性收益在行业内一直存在争议。基于热力系统的分析计算方法和蒸汽动力循环的基本原理,对某高效超超临界1 000 MW机组采用EC-BEST方案后热力系统的结构变化、汽水分布参数变化以及热力循环各主要能量转化环节的效率变化情况进行了详细分析。结果表明:采用EC-BEST方案后,再热蒸汽份额显著下降,再热循环的经济性增益降低;汽轮机各缸效率和功率比例均有变化,综合效果使汽轮机内效率比常规方案有一定提升;EC-BEST汽轮机的内效率是影响该方案经济性的关键,当EC-BEST汽轮机的内效率比常规方案小汽轮机的内效率高5.5百分点以上时,EC-BEST方案的经济性才会优于常规方案,EC-BEST技术才有应用价值。

The EC-BEST technology is proposed for the next generation of 700 ℃ advanced ultra supercritical power generation technology. Whether it has economic benefits when applying the EC-BEST technology to the current 600 ℃ ultra supercritical 1 000 MW units has been controversial all the time. On the basis of the calculation method for thermal dynamic system and basic principle of steam dynamic cycle, the changes of structure, steam water distribution parameter and efficiency of major energy conversion process in the thermal dynamic cycle of the thermal dynamic system in an ultra supercritical 1 000 MW unit applying the BEST technology were studied in detail. The results show that, by applying the BEST technology, the fraction of the reheat steam reduces obviously, and the benefit of the reheat cycle decreases. The efficiency and output power of each cylinder all changes, and the overall efficiency of the turbine increases to a certain degree. The BEST steam turbine efficiency is the key factor influencing the system＇s economy. The economy of the BEST scheme will be superior to the conventional scheme only if the turbine efficiency of the thermal system applying the BEST was 5.5 percent higher than that of the conventional thermal system, at that time the EC-BEST technology has application value.