新型661mm末级叶片直接空冷机组高背压供热技术  

High back pressure heating technology of 661mm last stage blades of direct air-cooling unit

作　　者：康朝斌 史鹏飞 张伟 王兴 刘卓荦 Kang Chaobin;Shi Pengfei;Zhang Wei;Wang Xing;Liu Zhuoluo(China Energy Science and Technology Research Institue Co.Ltd Taiyuan Branch.,Taiyuan 035503,China)

机构地区：[1]国家能源集团科学技术研究院有限公司太原分公司,山西太原035503

出　　处：《电力科技与环保》2022年第6期448-457,共10页Electric Power Technology and Environmental Protection

基　　金：国家重点研发计划(2020YFB0606302)。

摘　　要：直接空冷机组采用高背压供热方式可回收汽轮机乏汽,减少高品位蒸汽有用能损失,提高能源转换效率。受常规汽轮机末级叶片最小安全蒸汽量偏大、小容积流量全工况特性差等因素限制,直接空冷机组高背压供热时乏汽无法全部利用,造成大量高品质的乏汽有用能浪费,对机组经济性影响较大。采用EBSILON软件热力系统建模,对某330 MW直接空冷机组661 mm末级叶片高背压供热特性进行了研究,在热网循环水流量10000 t/h、温度在45℃~55℃范围内、机组负荷在200 MW~250 MW之间时,高背压凝汽器乏汽利用率范围为50%~90%,乏汽利用率偏低,机组冷源损失较大,供热期影响煤耗最高达到55 g/(kW·h),高背压供热经济性提升空间较大。针对高背压供热乏汽利用率低的问题,研发应用了小容积流量特性良好的新型661 mm末级叶片,新型661 mm末级叶片重新优化了气动特性和结构特性,具备相对容积流量最低25%工况安全运行的能力,在不影响纯凝工况经济性的同时,大幅提升了高背压供热技术的适应性。实现国内首次工程应用,高背压供热工况下,汽轮机可在超高排汽背压60 k Pa、超高排汽温度120℃长期稳定运行,机组负荷在150 MW~280 MW之间乏汽利用率达到100%,供热期消除了冷源损失,降低机组煤耗30 g/(kW·h),节能效果显著。Using high back pressure heating method in direct air-cooling unit can recover the exhausted steam of steam turbine.It reduces the loss of useful energy of high-grade steam and increases the energy efficiency.Limited by the large minimum safe steam capacity of the last stage blades of conventional steam turbines and the poor performance of low volume flow conditions,the exhausted steam can not be fully utilized in the high back pressure heating of direct air-cooled units.It results in a large amount of wasted useful energy with high pressure,which has a great impact on the unit economy.The heating characteristics of 661 mm last stage blades of a 330 MW direct air-cooling unit with high back pressure were studied by using EBSILON software.When the circulating water flow is 10000 t/h,the temperature is in the range of 45℃~55℃,and the unit load is in the range of 200 MW~250 MW,the exhausted steam utilization rate of high back pressure condenser is in the range of 50%~90%.The exhausted steam utilization rate is low,the unit cold source loss is larger,the coal consumption is about 55 g/(kW·h),the high back pressure heating economy is larger.In order to solve the problem of low utilization ratio of exhaust steam in high back pressure heating system,some measures are put forward.A new 661mm last stage blade and low pressure cylinder module with good performance of small volume flow is developed.New 661 mm end-stage blades have been re-optimized for aerodynamic and structural characteristics,and are capable of operating safely at a minimum of 25%relative volume flow without affecting the economy of pure condensation operation.It significantly improves the adaptability of high back pressure heating technology.Realizing the first engineering application in China,the steam turbine can run stably for a long time under the condition of high back pressure heating at60 kPa and 120℃of ultra-high exhaust steam back pressure.The utilization ratio of exhausted steam reaches 100%between 150 MW and 280 MW.The loss of cold sour

关 键 词：高背压供热 661 mm末级叶片 乏汽 小容积流量 

分 类 号：TM621[电气工程—电力系统及自动化] TK263.3[动力工程及工程热物理—动力机械及工程]