5 MW级超临界二氧化碳锅炉吹管方案比较分析

Comparison and analysis of steam blowing schemes for a 5 MW-level supercritical carbon dioxide boiler

为探索适用于超临界二氧化碳(S-CO_(2))锅炉的吹管工艺,以西安热工研究院有限公司5 MW级S-CO_(2)循环发电试验机组为研究对象,结合主辅机设备特性提出了开放式CO_(2)吹扫、封闭式CO_(2)吹扫以及用空气、水蒸气等介质进行替换的开放式吹扫共4个技术方案,从经济性、环保性、有效性、安全性等方面对上述方案进行了分析比较。结果表明:开放式CO_(2)吹扫方案成本高昂不环保,开放式空气吹扫方案气体动量远远达不到吹管质量要求,2个方案均不具有现实可行性;封闭式CO_(2)吹扫方案系统简单,操作便捷,但滤网需反复清理、更换费工费时,同时造成大量碳排放,若能搭配高效的化学清洗,则工期将大大缩短;开放式水蒸气吹扫工艺成熟,质量可靠,但变换水工质后加装临吹系统投资较大。考虑到未来S-CO_(2)锅炉有可能在设计阶段即考虑进水排水装置,将会使部分改造项变为标配项,则开放式水蒸气吹扫方案的成本有望显著降低。因此,综合来看,封闭式CO_(2)吹扫、开放式水蒸气吹扫方案具有较高的现实可行性,结合高效化学清洗的封闭式CO_(2)吹扫方案能减少滤网更换次数,具有更好的综合应用前景。

In order to explore the steam blowing process suitable for supercritical carbon dioxide(S-CO_(2)) boiler,four technical schemes such as open CO_(2) purging,closed CO_(2) purging,open air and open water steam purging are proposed based on the 5 MW S-CO_(2) cycle power generation test unit designed and built by Xi’an Thermal Power Research Institute Co.,Ltd.,combining with the characteristics of main and auxiliary equipment.Moreover,the above four schemes are compared from the aspects of economy,environmental protection,safety and efficiency.The results show that,the open CO_(2) purging scheme has high cost and is not environmental frendly,and the gas momentum of open air purging scheme is far from meeting the quality requirements of blowing pipe.Neither of the above two schemes is feasible.The closed CO_(2) purging scheme has simple system and convenient operation,but the filter screen needs to be cleaned and replaced repeatedly,which takes time and labor,and causes a lot of carbon emission.If it can be combined with efficient chemical cleaning,the purging time will be greatly shortened.The open steam purging process is mature and reliable in quality,but the investment of installing temporary purging system after using water as the fluid is large.Considering that some water inlet and drainage devices should be designed for S-CO_(2) boilers in the future,which makes some transformation items become standard items,the cost of the scheme is expected to be significantly reduced.Therefore,in a comprehensive way,both the closed S-CO_(2) purging and open steam purging schemes have higher practical feasibility.The closed S-CO_(2) purging scheme combining with high efficient chemical cleaning can reduce the replacement times of filter screen and has a better comprehensive application prospect.