宋畅1, 吕俊复2, 杨海瑞2, 王树民1, 凌文1, 岳光溪2
1．神华集团,北京市 西城区 100031
2．清华大学,北京市 海淀区 100084
SONG Chang
1. Shenhua Group, Xicheng District, Beijing 100031, China;
2. Tsinghua University, Haidian District, Beijing 100084, China
宋畅(1965),男,教授级高级工程师、硕士,从事洁净煤发电技术研究和管理工作,17000159@shenhua.cc。
基金项目： 国家重点研发计划项目(2016YFB0600201); The National Key R&D Program of China(2016YFB0600201);
文章编号: 0258-8013(2018)02-0338-10 中图分类号: TK224
摘要
开发超临界循环流化床（CFB）锅炉是国际CFB界的目标,它兼备了清洁利用劣质燃料和高效发电两个优势,对于煤炭的清洁开发利用具有至关重要的地位。中国的科技人员在国家863计划和国家科技支撑计划的支持下,开展系统的研究开发,全面突破了300MW亚临界自然循环跨越到600MW超临界强制循环带来的巨大的理论和工程挑战,回答了工程上提出的科学和技术问题,在神华白马电厂成功建设了世界上第一台600MW超临界CFB锅炉及相应的辅助系统。进而将这些研究成果成功拓展用于350MW超临界CFB锅炉上,已经批量投产。这些研究积累为开发提供了基础。目前正在开展660MW超超临界CFB锅炉的技术关键如热偏差、超低排放、低能耗等研究,并已经取得了阶段性进展。
关键词 : 600MW; 超临界及超超临界; 循环流化床(CFB)锅炉; 热偏差; 低能耗; 超低排放;
0 引言
循环流化床(CFB)是劣质煤清洁煤燃烧最好技术之一[1],但在供电效率方面未见优势。提高蒸汽参数能够显著提升火电发电效率,因此发展超(超)CFB锅炉技术、通过提高蒸汽参数提高效率,是CFB锅炉的发展方向。这是国际CFB界的梦想。CFB炉膛温度和热流密度整体较低,热流密度在炉膛底部最大,沿高度逐渐减小,恰好与工质温度沿炉膛的变化趋势相反,这些特点有利于超临界下水冷壁安全性[2]。此外,由于快速流态化的基本特点,CFB炉内温度非常均匀[3],热负荷分布要比煤粉炉均匀很多。因此,CFB燃烧技术更适合与超临界甚至超超临界蒸汽循环相结合。
中国在20世纪末开始研究超临界CFB锅炉的技术可行性。2002年,在国家“863”计划的支持下,开展了超临界CFB锅炉技术可行性探索研究[4]。进而在国家科技支撑计划的支持下,开展600MW超临界CFB锅炉的工程示范并取得成功,进而将有关的技术拓展应用开发了350MW超临界CFB锅炉,也实现了产业化。在此基础上,为了进一步提高效率,现正在研制660MW超超临界CFB锅炉。结合发电煤耗和污染排放的要求,同时开展了流态优化和超低排放的研究。
1 循环流化床燃烧技术及流程优化
CFB燃烧的技术基础是流态化。传统CFB锅炉沿用了化工流化床反应器的设计理念[5],导致CFB锅炉机组厂用电率高[6]。大颗粒物料流化引发燃烧室受热面的磨损[7]。因此有必要对CFB锅炉的流态进行分析和优化[8]。另外,超临界CFB的炉膛尺寸超过了已有的实践范围,因此掌握超大炉膛的气固两相流动性质至关重要。
1.1 循环流化床燃烧的流态分析
CFB炉膛中,下部是粗颗粒形成的鼓泡床或湍动床,上部是细颗粒在自由空域形成的快速床[9]。炉膛中的颗粒可分成两类：能够参与循环并直接影响上部受热面换热的有效床料,以及始终停留在炉膛底部无法被夹带的无效床料[10]。无效物料对于保证粗颗粒着火和停留时间是必要的。而上部快速流态化中,颗粒浓度沿轴向的分布与表观气速、床料量、循环流率等有关[11-13]。研究发现,影响大颗粒的燃尽和着火的粗颗粒存量过多[11]。当快速流态化出现后,床存量增加仅仅改变过渡区的颗粒浓度,而稀相区和底部密相区的颗粒浓度保持不变[10]。影响到传热和燃烧的只是上部的快速床[14]。Liu et al.通过模型预测床压降对传热的影响,在相同粒径分布和负荷时,床压降减少1kPa,传热系数仅降低2%[15]。因此可以降低无效床料的存量、保持有效床料的存量实现减小风机功耗、缓解磨损[16],见图1。
图1 传统型和节能型CFB锅炉床存量对比
Fig. 1 Bed inventory in classical and novel CFB
床存量的增加,循环量提高,上部稀相区的颗粒聚团的概率增大。由于颗粒团的终端沉降速度要大于单一颗粒,因此在气流的作用下会产生强烈的周期性聚并和破裂[17]。这种返混现象会延长颗粒在炉膛的停留时间,提高可燃物的燃尽率[18]。另一方面,过渡区颗粒浓度增大会提高气固流场的动量和刚度,二次风背压增大、穿透深度减小[19]。进入核心区域的氧气减少,大量氧气停留在边壁区域,造成局部贫氧区[20-21],抑制煤颗粒的燃烧。由于两个方面的对于燃烧效率影响,理论上存在一个最佳床存量。
1.2 循环流化床燃烧的流态设计
CFB锅炉是“一进二出”的物料平衡体系[22],这里的“一进”指的是由给煤、石灰石和惰性床料形成的灰分;“二出”指的是炉膛底部的排渣和分离器出口的飞灰逃逸[9]。该系统的平衡是由各个粒径的颗粒均达到平衡的积分结果。宽筛分的灰颗粒进入CFB后,由于系统对不同粒度颗粒的保存能力不同,粗颗粒难以被扬析夹带容易被底部排渣排出系统,而过细颗粒难以被分离器分离会被烟气带离系统。达到平衡后,CFB内的物料粒度分布会在系统保存效率最高点附近形成峰值。研究表明,分离器效率和排渣效率的提高,会极大的提升有效物料在总存量中的比例[23],甚至回料阀的性能也会直接影响平衡结果[24]。
根据理论研究和实践经验,Yue et al.提出了CFB流态图谱,使用流化风速和循环流率两个物理量,来描述密相区以上的快速床状态[9]。根据该图,保证稀相区颗粒浓度不变,达到最优床压降,从而实现减小密相区床层厚度,减小风机功耗,降低CFB机组的厂用电率的目的。为了实现CFB锅炉在减小床存量的同时,稀相区的颗粒浓度保持不变,则必须改善床质量,提高有效物料在床存量中的比例。在实际设计中,通过流态图谱优化有效物料的存量和质量,实现流态重构。
基于流态重构理论,已经开发15~300MW的系列CFB锅炉[10],超过百台运行[16,25]。
1.3 超大炉膛内气固流动
超临界CFB锅炉因为水动力的要求,炉膛的高度达到50m以上,超过了已有的实践范围。由于CFB锅炉内的气固流动规律,直接决定了颗粒悬浮浓度,对于局部换热系数以及燃烧份额分布非常重要[26]。因此掌握超大炉膛内的气固流动规律,对于超临界甚至超超临界CFB锅炉的设计与运行有重要意义。为此搭建了高度为54m的实验系统,研究了超高炉膛中气固两相流动的基本性质[27],见图2,确认了超高炉膛的关键参数,回答了工程提出的问题。
600MW超临界CFB的床截面积超过了已有的所有实践。物料浓度分布也是必须掌握的问题,为此进行了系统的研究并进行了模型化,建立了超大床面水平分布计算模型。考虑高度方向的分布特点,建立了CFB锅炉近壁区物料浓度分布模型,见图3。
图2 轴向物料浓度分布随颗粒存量和提升管高度的变化关系
Fig. 2 Variations of axial voidage profile with solid inventory and riser height
图3 浓度分布模型计算误差
Fig. 3 Comparison of solid suspension density distribution between measurement and model prediction
为了强化气固混合改善燃烧效率,采用双布风板结构。这就产生了两侧炉膛的翻床问题[28]。单个布风板内还存在同床波动问题。这些现象在亚临界时一定条件下可以忍受,但是超临界下影响到水冷壁的安全性,必须严格避免。研究揭示了炉膛内物料流动不对称导致了上部的物料横向流动是发生翻床的根本原因[29-30];同床波动产生的风源激励机制[31],提出了相应的预防措施。
随着锅炉容量增加,必然采用多循环回路并联的布置,这带来多分离器并联回路之间气固流动的静态不均匀性问题[32-33]和动态不稳定问题。基于相似准则,研究发现了发生这些问题的几何条件和操作条件[34]。
对超大床面涉及到的返料[35-36]和给煤扩散[37-38]、二次风的穿透[39-40]、炉膛中气固流动结构[41-42]以及整体布置[43]对物料平衡、热平衡的影响[44-45]进行了系统的研究,获得了系列的原创新成果,为工程设计提供了依据。
2 超临界循环流化床锅炉的开发
超(超)临界循环流化床锅炉的技术核心是水冷壁的设计问题。这涉及到水冷壁的热负荷及其分布、管内超临界水的流动与传热。在亚临界条件下,自然循环的受热自适应能力使得设计中不用考虑热负荷问题,但是超临界下必须掌握热负荷的分布。
2.1 循环流化床燃烧室受热面的热流密度分布
CFB炉膛内受热面热流密度分布的本质是床向受热面的局部换热系数问题。针对气固两相流内受热面的换热特性进行了详细的研究[46],CFB炉膛中的换热机理可以简化为颗粒对流和空间辐射两项[47]。针对这两项机理,中国研究者开发了传热系数的测量手段,对不同容量的锅炉进行了详尽的工业测试,并提出CFB燃烧室床向受热面中的换热系数半经验关联式[14],考虑了床温、局部颗粒浓度、膜式壁几何尺寸以及管内工质温度的影响,能很好的符合工业测试以及国外学者报道的实验数据,见图4。
图4 换热系数与物料浓度和温度的关系
Fig. 4 Heat transfer coefficients vs suspension particle density and temperature
根据前述的物料浓度模型和床向受热面换热模型即可获得局部换热系数以及热流密度分布。为了检验其结果,在135MW和300MW CFB锅炉上利用有限元分析[48]进行热态现场测试[49-51],典型结果见图5。这一结果纠正了此前关于CFB水冷壁热流炉膛中间高、角部低的错误认识[52-53],为水冷壁的设计提供了坚实的基础。
135MW和300MW CFB锅炉上的现场测试结果与模型计算结果相比,见图6,该模型具有较好的准确性,与85%的数据误差都在10%以内。
图5 CFB锅炉沿水平方向热流密度分布
Fig. 5 Heat flux distribution along horizontal direction in a CFB furnace
图6 热流密度分布模型预测准确性
Fig. 6 Heat flux model accuracy (predicted vs. measured)
2.2 垂直管水冷壁管内超(超)临界水流动换热
超临界锅炉的关键是水冷壁。煤粉炉通过螺旋盘管实现高质量流速,但CFB中水冷壁考虑防磨必须用垂直管,工质流速远低于煤粉炉,超临界CFB无法借用煤粉炉的超临界知识和经验,低质量流速、低热流密度,此前没有该条件下的超临界水动力数据,因此开展了该条件下管内超临界水流动与换热的详细研究[54-55],填补了研究空白,见图7,并建立了换热和流动模型。发现了超临界CFB中管内工质质量流速的安全下限为36kg/(m2•s),远低于经典判据计算的200kg/(m2•s)[56]。进而开发了低质量流速一次上升垂直水冷壁、非连续双面受热水冷
图7 水动力学数据的研究
Fig. 7 Hydrodynimic investigation
壁等,用于炉膛设计。利用模型预测了水动力安全性[57-58],水冷壁出口汽温偏差模型预测小于20℃,该结果与锅炉实际运行数据非常吻合,见图8,汽温偏差实际运行不足17℃[59]。水动力学的工作涵盖了超临界CFB的参数范围,但是对于超超临界CFB锅炉,还要进行更宽范围的研究。超超临界CFB的技术核心是热偏差问题,但是热偏差的重点从水冷壁转移到末级过热器和末级再热器上。
图8 600MW CFB锅炉水冷壁出口蒸汽温度模型与实际运行数据对比
Fig. 8 Comparison of water wall outlet steam temperature between operation and prediction along horizontal direction in 600MW CFB boiler
2.3 超临界循环流化床锅炉工程实践
根据整体布置需要,发明了纵流式流化床换热器和相应的受热面固定结构,解决了埋管振动磨损的世界难题;开发了超临界CFB锅炉设计技术,首创了超临界CFB全逆流热力流程,解决了低温燃烧低负荷汽温偏低的问题;设计开发了600MW超临界CFB锅炉,结构上创造了诸多世界之最;开发了创新结构的制造工艺。
针对超临界CFB发电机组的控制问题,提出了即燃碳的概念和软测量方法,解决了CFB热惯性大的世界控制难题,负荷与AGC命令跟随性极好,给水流量、蒸汽温度的波动得到彻底改善,实现了汽温的精准控制和负荷自动调节[60-61]。
研制了基于机理模型的600MW超临界CFB发电机组仿真机,用于培训运行人员,并为控制逻辑检验和启动调试提供指导。
开发了系列辅机、系统集成技术,和安装、调试、启动技术,建设了世界上第一台600MW超临界CFB锅炉工程示范,于2013年通过测试运行。锅炉燃用灰分43.82%、硫分3.3%的劣质贫煤。4年多的运行实践表明,白马600MW超临界CFB锅炉性能全面达到预期。尽管煤质较差,但是相同SO2排放浓度下脱硫石灰石当量消耗仅为国外的80%,NOx原始排放更是低于国外的40%。锅炉受热面 设计计算精准,运行各处烟温、汽温与设计值完全一致。
采用600MW超临界CFB锅炉压法的技术,拓展研发了350MW超临界CFB锅炉,2015年9月,第一台350MW超临界CFB锅炉于山西国金通过测试,投入商业运行。350MW超临界CFB锅炉采用单炉膛,一次中间再热。炉膛内布置有屏式过热器和屏式再热器。炉后布置3个汽冷旋风分离器,无外置换热器。尾部双烟道结构,前烟道布置有低温再热器,后烟道布置有中温过热器和低温过热器,省煤器和空预器布置在前后烟道合并后的竖井区域。截止目前共有12台350MW超临界CFB锅炉投运,另有70余台在建。
白马600MW超临界CFB锅炉示范电站的顺利运行,为更高参数锅炉的开发积累了经验,开展了超超临界CFB锅炉的探索[62]。在国家十三五重点研发计划支持下,目前正在开展相关的研究工作,主要集中于超超临界、超低排放和超低能耗3个方面,预计工程示范将于2020年建成,满足最新煤耗要求和超低排放要求[63]。
3 超低排放循环流化床燃烧
超低排放是660MW超超临界CFB锅炉的重要内容。CFB采用低温燃烧,炉内存有大量还原性物料,NOx排放具有天然优势,通常原始排放可满足200mg/m3以下。添加石灰石炉内脱硫能实现90%以上的脱硫效率[64-65],可直接满足多数国家的排放要求。我国的标准更严,NOx和SO2均低于100mg/m3,传统CFB锅炉面临巨大的挑战[66]。清洁能源行动计划进一步要求超低排放：c(NOx)<50mg/m3、c(SO2)<35mg/m3,传统CFB无法满足。为此,许多CFB锅炉不得不安装烟气净化设备,CFB锅炉低成本污染脱除优势不再[67]。
中国研究者从流化床燃烧机理出发,提出了基于炉内脱硫和低氮燃烧的超低排放技术路线,从而减少炉外脱硫脱硝设备压力。对于部分燃用煤种,可以实现炉内NOx和SO2双重超低排放。
3.1 基于炉内高效脱硫的SO控制
CFB燃烧中,燃料的硫分转化为SO2;石灰石给入后发生煅烧反应生成多孔的CaO[65]。如图9所示,SO2扩散到CaO表面和内孔,在有氧气情况下,CaO和SO2反应生成CaSO4。由于CaSO4的摩尔体积远大于CaO,因此生成的CaSO4逐渐堵塞孔 隙[68]。当所有表面及孔隙被覆盖后反应停止。因此对于小颗粒而言,反应表面积更大、孔隙更接近于表面,反应导致孔隙堵塞的可能性低,脱硫转化率较高。大量的测试表明,CaSO4产物层厚度在数十微米量级[69]。也就是说,粒径大于200μm的石灰石必然有部分未反应。
图9 石灰石脱硫过程示意图
Fig. 9 Schematic diagram of absorption of sulfur dioxide by sorbents
必要的停留时间是实现高效脱硫的基本条件。石灰石的粒径范围应该与分离器的分离器效率相互匹配。若分离效率很高,脱硫石灰石粒度可以细一些。传统的CFB锅炉由于分离器效率不够高,不得不选择较粗的石灰石脱硫,石灰石通常为0~1000μm,中位径在300μm左右,甚至更粗,因此钙硫摩尔比较高。若能显著提高分离器效率,可以使用细粒径石灰石,例如粒度范围为0~200μm,中位径在20~50μm,见图10。较细颗粒粒径提高了石灰石利用率,实现高效炉内脱硫,也减小对于NOx的促进作用[70]。
图10 高效炉内脱硫的石灰石粒度推荐范围
Fig. 10 Recommended particle size distribution of limestone for higher efficiency SO2 capture
还有许多因素会影响石灰石脱硫效率,如床温、气氛等[71]。当低于800℃时,煅烧反应速率明显下降,限制了脱硫反应的速率;而当温度高于 850℃后,CaO孔隙烧结导致脱硫表面积减少,并且CaSO4分解速率显著加快。此外,由于脱硫反应需要在氧化性条件下进行,因此控制炉内气氛对于脱硫反应也有一定影响。
因此,基于炉内高效脱硫的SO2超低排放要求,反应温度控制在850°C附近,兼顾脱硫和燃烧效率;配风要高于脱硫需要的最低氧量,保证脱硫反应在氧化性气氛下进行;提高分离器效率,降低石灰石粒度,提高石灰石比表面积和停留时间,提高石灰石利用率。
3.2 基于低氮燃烧的NO控制
针对流化床燃烧条件下NOx排放,国内外学者进行了众多的研究[72-73]。CFB锅炉采用800~900℃低温燃烧方式,几乎没有热力型NOx生成,几乎全部都是燃料型NOx[74]。CFB锅炉下部密相区鼓泡床包含近似处于最小流化状态的乳化相和固含率极低的气泡相[75]。乳化相中气速接近于颗粒最小流化风速umf。随床料粒径减小,乳化相内部气速变小,燃料颗粒位于乳化相中,直接获得的O2将显著变少。颗粒变细后,O2从气泡相向乳化相传质阻力增大[76],这将导致颗粒处于严重缺氧的还原性气氛中[9],大大抑制了乳化相中燃料颗粒NOx的生成[77],见图11(a)。
图11 CFB锅炉内流态示意图
Fig. 11 Schematic diagram of the fluidization regime in CFB boilers
在CFB炉膛上部区域的快速床中,燃料颗粒大量存在于颗粒团中。颗粒团中的燃料热解条件与乳化相中类似,相比于底部鼓泡床发生了物相倒置,分离的气泡相变成连续相,而连续的乳化相则变成由颗粒团组成的分散相。其传质与传热规律仍可用鼓泡床进行比拟[78]。由于细颗粒的团聚倾向强于粗颗粒,因此床料变细后使得包裹于颗粒团内的燃料颗粒面临更大的传质阻力。对于处于稀相区颗粒团中的小颗粒燃料,也是处于贫氧的还原性气氛中,同样抑制了NOx的生成[79],见图11(b)。
如上所述,还原性气氛同时存在于底部密相区乳化相和顶部稀相区颗粒团中,会导致大量还原性的气体如CO的生成,这些还原性气体会进一步还原已生成的NOx[80]。
综上所述,基于低氮燃烧的NOx超低排放,要求温度控制在850℃附近,从而兼顾脱硫和燃烧效率,核心是提高系统对细物料的综合保存效率,减小床料粒径,改善床料质量;改变二次风高度,延迟二次风进入时间,扩大还原性气氛区域[81]。
这些分析已经得到实践验证[81],仅仅通过炉内石灰石和低氮燃烧,可以原始排放可以达到NOx和SO2双重超低[67]。这为660MW超超临界CFB的超低排放提供了技术支持。
4 结论
CFB锅炉燃烧技术在中国燃煤污染控制和劣质煤利用领域重要地位。在国家863计划和国家科技支撑计划的支持下,系统地研究了600MW超临界CFB锅炉涉及到的所有技术问题,全面突破了300MW亚临界自然循环跨越到600MW超临界强制循环带来的巨大的理论和工程挑战,在神华白马电厂成功建设了世界上第一台600MW超临界CFB锅炉及相应的辅助系统,实现了国际CFB界的梦想。将这些研究成果成功拓展用于350MW超临界CFB锅炉上,已经批量投产。这些研究积累为开发提供了基础。目前正在开展660MW超超临界CFB锅炉的技术关键如热偏差、超低排放、低能耗等研究,并已经取得了阶段性进展。
参考文献
[1]KoornneefJ,JungingerM,FaaijA.Development of fluidized bed combustion—an overview of trends,performance and cost[J].Progress in energy and combustion science,2007,33(1):19-55.
[2]吕俊复,于龙,岳光溪,等.循环流化床锅炉水冷壁的热流密度分布[J].动力工程,2007,27(3):336-340.LüJunfu,YuLong,YueGuangxi,et al.Heat flux distribution along water walls of circulating fluidized boilers[J].Journal of Power Engineering,2007,27(3):336-340(in Chinese).
[3]YerushalmiJ,Turner DH,Squires AM.The fast fluidized bed[J].Industrial & Engineering Chemistry Process Design and Development,1976,15(1):47-53.
[4]吴玉新,吕俊复,张建胜,等.800MWe超临界循环流化床锅炉概念设计[J].锅炉技术,2004,35(3):1-5,48.WuYuxin,LüJunfu,ZhangJiansheng,et al.Conceptual design of an 800MWe supercritical pressure circulating fluidized bed boiler[J].Boiler Technology,2004,35(3):1-5,48(in Chinese).
[5]LotharR,MartinH,Ludolf P.Methodofandapparatus for carrying out an exothermic process:U.S. Patent 4111158[P].1978-09-05.
[6]杨石,杨海瑞,吕俊复,等.新一代节能型循环流化床锅炉燃烧技术[J].动力工程,2009,29(8):728-732,788.YangShi,YangHairui,LüJunfu,et al.The new generation combustion technology for energy saving circulating fluidized bed boilers[J].Journal of Power Engineering,2009,29(8):728-732,788(in Chinese).
[7]Yang HR,ZhangH,Lu JF,et al.Novel CFB boiler technology with reconstruction of its fluidization state[C]//Proceedings of the 20th International Conference on Fluidized Bed Combustion.Berlin,Heidelberg:Springer,2009:195-199.
[8]岳光溪,吕俊复,徐鹏,等.循环流化床燃烧发展现状及前景分析[J].中国电力,2016,49(1):1-13.YueGuangxi,LüJunfu,XuPeng,et al.The up-to-date development and future of circulating fluidized bed combustion technology[J].Electric Power,2016,49(1):1-13(in Chinese).
[9]YueGuangxi,LuJunfu,ZhangHairui,et al.Design theory of circulating fluidized bed boilers[C]//Proceedings of the 18th International Conference on Fluidized Bed Combustion.Toronto,Ontario,Canada:ASME,2005:135-146.
[10]YangHairui,ZhangHai,YangShi,et al.Effect of bed pressure on performance of a CFB boiler[J].Energy & Fuels,2009,23(6):2886-2890.
[11]Bai DR,JinY,Yu ZQ,et al.The axial distribution of the cross-sectionally averaged voidage in fast fluidized beds[J].Powder Technology,1992,71(1):51-58.
[12]LiJinghai,TungY,KwaukM.Axial voidage profiles of fast fluidized beds in different operating regions[M]//Basu P,Large J F.Circulating Fluidized Bed Technology II.Amsterdam:Elsevier,1988:193-203.
[13]XuGuangwen,GaoShiqiu.Necessary parameters for specifying the hydrodynamics of circulating fluidized bed risers—a review and reiteration[J].Powder Technology,2003,137(1-2):63-76.
[14]Lu JF,Zhang JS,Yue GX,et al.Method of calculation of heat transfer coefficient of the heater in a circulating fluidized bed furnace[J].Heat Transfer-Asian Research,2002,31(7):540-550.
[15]LiuXuemin,ZhangMan,LuJunfu,et al.Effect of furnace pressure on heat transfer in a 135MW CFB boiler[J].Powder Technology,2015,284:19-24.
[16]YangHairui,YueGuangxi,ZhangHai,et al.Updated design and operation experience of CFB boilers with energy saving process in China[R].VGB PowerTech No.7.2011:49-53.
[17]BerrutiF,Pugsley TS,GodfroyL,et al.Hydrodynamics of circulating fluidized bed risers:a review[J].The Canadian Journal of Chemical Engineering,1995,73(5):579-602.
[18]MoXin,WangPeining,YangHairui,et al.A hydrodynamic model for circulating fluidized beds with low riser and tall riser[J].Powder Technology,2015,274:146-153.
[19]杨建华,杨海瑞,岳光溪.循环流化床二次风射流穿透规律的试验研究[J].动力工程,2008,28(4):509-513.YangJianhua,YangHairui,YueGuangxi.Experimental study on secondary air jet penetration in circulating fluidized bed[J].Journal of Power Engineering,2008,28(4):509-513(in Chinese).
[20]LüJunfu,WangQimin,LiYong,et al.Unburned carbon loss in fly ash of CFB boilers burning hard coal[J].Tsinghua Science and Technology,2003,8(6):687-691.
[21]XiaoXianbin,YangHairui,ZhangHai,et al.Research on carbon content in fly ash from circulating fluidized bed boilers[J].Energy & Fuels,2005,19(4):1520-1525.
[22]Yates JG.Fundamentals of fluidized-bed chemical processes[M].London:Butterworths,1983.
[23]Lu JF,Feng JK.On design of CFBC boilers[C]// Proceeding of the 5th International Symposium on Coal Combustion.Nanjing,China,2003:309-313.
[24]YangShi,YangHairui,ZhangHai,et al.Impact of operating conditions on the performance of the external loop in a CFB reactor[J].Chemical Engineering and Processing:Process Intensification,2009,48(4):921-926.
[25]SuJianmin,Hu Nan.Application of fluidization reconstruction energy-saving combustion technology on 300MW CFB boiler[J].Advanced Materials Research,2012,516-517:140-145.
[26]XuGuangwen,NomuraK,GaoShiqiu,et al.More fundamentals of dilute suspension collapse and choking for vertical conveying systems[J].AIChE Journal,2001,47(10):2177-2196.
[27]HuNan,ZhangHai,YangHairui,et al.Effects of riser height and total solids inventory on the gas-solids in an ultra-tall CFB riser[J].Powder Technology,2009,196(1):8-13.
[28]Le GuevelT,ThomasP.Fuel flexibility and petroleum coke combustion at Provence 250 MW CFB[C]// Proceedings of the 17th International Conference on Fluidized Bed Combustion.Jacksonville,Florida,USA:ASME,2003,643-649.
[29]LiJinjing,WangWei,YangHairui,et al.Bed inventory overturn in a circulating fluid bed riser with pant-leg structure[J].Energy & Fuels,2009,23(5):2565-2569.
[30]李金晶,胡南,姚宣,等.裤衩腿型循环流化床炉膛的翻床实验[J].中国矿业大学学报,2011,40(1):54-59.LiJinjing,HuNan,YaoXuan,et al.Experimental study of the bed Inventory overturn in pant-legs furnace of CFB boiler[J].Journal of China University of Mining & Technology,2011,40(1):54-59(in Chinese).
[31]姜华伟,吕俊复,胡南,等.静床高对大截面流化床锅炉床压横向波动影响的模型[J].煤炭学报,2016,41(10):2533-2540.JiangHuawei,LüJunfu,HuNan,et al.Modelling research on effects of static bed height on lateral bed pressure fluctuations in large cross-section circulating fluidized bed boilers[J].Journal of China Coal Society,2016,41(10):2533-2540(in Chinese).
[32]Yue GX,Yang HR,NieL,et al.Hydrodynamics of 300MWe and 600MWe CFB boilers with asymmetric cyclone layout[C]//Proceedings of the 9th International Conference on Circulating Fluidized Beds.Hamburg,2008:153-158.
[33]YangS,Yang HR,LiuQ,et al.Research on flow non-uniformity in main circulation loop of a CFB boiler with multiple cyclones[C]//Proceedings of the 20th International Conference on Fluidized Bed Combustio.Berlin,Heidelberg:Springer,2009:341-344.
[34]MoXin,CaiRunxia,HuangXiaodan,et al.The effects of wall friction and solid acceleration on the mal-distribution of gas-solid flow in double identical parallel cyclones[J].Powder Technology,2015,286:471-477.
[35]Chen XP,Liu DY,Chen ZD,et al.Experimental study on particle feeding and mixing in the bottom zone of a circulating fluidized bed[C]//Proceedings of the 20th International Conference on Fluidized Bed Combustion.Berlin,Heidelberg:Springer,2009:324-329.
[36]LiuDaoyin,ChenXiaoping.Experimental profiles of lateral mixing of feed particles in a three-dimensional fluidized bed[J].AIChE Journal,2011,57(6):1459-1469.
[37]Chen HP,Tian LN,DuQ,et al.Experimental study on coal feeding property of 600MW CFB boiler[C]// Proceedings of the 20th International Conference on Fluidized Bed Combustion.Berlin,Heidelberg:Springer,2009:453-458.
[38]Liu DY,Chen XP,LiangC,et al.Solids mixing in the bottom zone of fluidized beds[C]//Proceedings of the 20th International Conference on Fluidized Bed Combustion.Berlin,Heidelberg:Springer,2009:459-463
[39]Zhou XL,Cheng LM,Wang QH,et al.Study of air jet penetration in a fluidized bed[C]//Proceedings of the 20th International Conference on Fluidized Bed Combustion.Berlin,Heidelberg:Springer,2009:453-458.
[40]Zhou XL,Cheng LM,Wang QH,et al.Influence of secondary air ratio on gas-solid mixing and combustion in a 300MWe CFB boiler furnace[C]//Proceedings of the 2010 International Conference on E-Product E-Service and E-Entertainment.Henan,China:IEEE,2010:1-4.
[41]DongWeigang,WangWei,LiJinghai.A multiscale mass transfer model for gas-solid riser flows:part 1-sub-grid model and simple tests[J].Chemical Engineering Science,2008,63(10):2798-2810.
[42]DongWeigang,WangWei,LiJinghai.A multiscale mass transfer model for gas-solid riser flows:part II-sub-grid simulation of ozone decomposition[J].Chemical Engineering Science,2008,63(10):2811-2823.
[43]李战国,刘志成,贺军,等.旋风分离器的入口烟道布置对性能的影响[J].中国电机工程学报,2009,29(17):1-7.LiZhanguo,LiuZhicheng,HeJun,et al.Influence of inlet duct layouts on cyclone performance[J].Proceedings of the CSEE,2009,29(17):1-7(in Chinese).
[44]LuJiayi,LuXiaofeng,HeHonghao,et al.Combustion acteristics of the external circulation loop on Baima's 300 MWe circulating fluidized bed boiler[J].Energy & Fuels,2011,25(8):3456-3464.
[45]LuJiayi,LuXiaofeng,LiuHanzhou,et al.Calculation and analysis of dissipation heat loss in large-scale circulating fluidized bed boilers[J].Applied Thermal Engineering,2010,30(13):1839-1844.
[46]Grace JR.Heat transfer in circulating fluidized beds[M]// Basu P.Circulating Fluidized Bed Technology.Amsterdam:Elsevier,1986.
[47]ZhangRuiqing,YangHairui,LuJunfu,et al.Theoretical and experimental analysis of bed-to-wall heat transfer in heat recovery processing[J].Powder Technology,2013,249:186-195.
[48]Andersson BA,LecknerB.Experimental methods of estimating heat transfer in circulating fluidized bed boilers[J].International Journal of Heat and Mass Transfer,1992,35(12):3353-3362.
[49]WangYu,LuJunfu,YangHairui,et al.Measurement of heat transfer in a 465t/h circulating fluidized bed boiler[C]//Proceedings of the 18th International Conference on Fluidized Bed Combustion.Toronto,Ontario,Canada:ASME,2005:327-335.
[50]ZhangRuiqing,YangHairui,ZhangHai,et al.Research on heat transfer inside the furnace of large scale CFB boilers[C]//Proceedings of the 10th International Conference on Fluidized Beds and Fluidization Technology.Sun River,Oregon,USA:ECI,2011:66-74.
[51]WuYuxin,LuJunfu,ZhangJiansheng,et al.Heat Flux and Hydrodynamics of the membrane wall of supercritical pressure circulating fluidized bed boiler[C]//Proceedings of the 5th International Symposium on Multiphase Flow,Heat Mass Transfer and Energy Conversion.Xian,China,2005.
[52]ZhangRuiqing,YangHairui,HuNan,et al.Experimental investigation and model validation of the heat flux profile in a 300 MW CFB boiler[J].Powder Technology,2013,246:31-40.
[53]ZhangP,Lu JF,Yang HR,et al.Heat transfer coefficient distribution in the furnace of a 300MWe CFB boiler[C]// Proceedings of the 20th International Conference on Fluidized Bed Combustion.Berlin,Heidelberg:Springer,2009:167-171.
[54]潘杰,杨冬,朱探,等.超临界压力水在垂直上升内螺纹管中的传热特性[J].化工学报,2011,62(2):307-314.PanJie,YangDong,ZhuTan,et al.Heat transfer acteristics of supercritical pressure water in vertical upward rifled tube[J].CIESC Journal,2011,62(2):307-314(in Chinese).
[55]潘杰,杨冬,董自春,等.垂直上升光管内超临界水的传热特性试验研究[J].核动力工程,2011,32(1):75-80.PanJie,YangDong,DongZichun,et al.Experimental investigation on heat transfer acteristics of water in vertical upward tube under supercritical pressure[J].Nuclear Power Engineering,2011,32(1):75-80(in Chinese).
[56]李舟航,张大龙,吴玉新,等.垂直上升光管内超临界水的传热恶化分析和判据[J].中国电机工程学报,2014,34(35):6304-6310.LiZhouhang,ZhangDalong,WuYuxin,et al.A new criterion for predicting deterioration of heat transfer to supercritical water in smooth tubes[J].Proceedings of the CSEE,2014,34(35):6304-6310(in Chinese).
[57]LiY,NieL,Hu XK,et al.Structure and performance of a 600MWe supercritical CFB boiler with water cooled panels[C]//Proceedings of the 20th International Conference on Fluidized Bed Combustion.Berlin,Heidelberg:Springer,2009:132-136.
[58]李燕,李文凯,吴玉新,等.带隔墙的600MW超临界循环流化床锅炉水冷壁水动力特性[J].中国电机工程学报,2008,28(29):1-5.LiYian,LiWenkai,WuYuxin,et al.Hydrodynamics of the water wall in a 600 MW supercritical circulating fluidized bed boiler with water cooled panels within the furnace[J].Proceedings of the CSEE,2008,28(29):1-5(in Chinese).
[59]YueG,LingW,LuJ,et al.Development and demonstration of the 600 MW supercritical CFB boiler in Baima power plant[C]//Proceedings of the 22nd International Conference on Fluidized Bed Conversion.Turku,Finland,2015.
[60]GaoM,LiuJ,YueG.Investigation on load control of a 600MW supercritical circulating fluidized bed boiler [C]//Proceedings of the 11st International Conference onFBC.2014,1:711-719.
[61]GaoMingming,ChangTaihua,GaoXiangxiang.Research in data stream clustering based on Gaussian Mixture Model Genetic Algorithm[C]//Proceedings of the 2nd International Conference on Information Science and Engineering.Hangzhou,China,China:IEEE,2010:3904-3907.
[62]吕俊复,张缦,杨海瑞,等.简约型660MW超超临界循环流化床锅炉设计开发[J].中国电机工程学报,2014,34(5):741-747.LüJunfu,ZhangMan,YangHairui,et al.Conceptual design of a simplified 660MW ultra-supercritical circulating fluidized bed boiler[J].Proceedings of the CSEE,2014,34(5):741-747(in Chinese).
[63]蔡润夏,吕俊复,凌文,等.超(超)临界循环流化床锅炉技术的发展[J].中国电力,2016,49(12):1-7.CaiRunxia,LüJunfu,LingWen,et al.Progress of supercritical and ultra-supercritical circulating fluidized bed boiler technology[J].Electric Power,2016,49(12):1-7(in Chinese).
[64]Tullin CJ,GoelS,MoriharaA,et al.Nitrogen oxide(NO and N2O) formation for coal combustion in a fluidized bed:effect of carbon conversion and bed temperature[J].Energy & Fuels,1993,7(6):796-802.
[65]Anthony EJ,Granatstein DJ.Sulfation phenomena in fluidized bed combustion systems[J].Progress in Energy and Combustion Science,2001,27(2):215-236.
[66]LiJingji,YangHairui,WuYuxin,et al.Effects of the Updated National Emission regulation in China on circulating fluidized bed boilers and the solutions to meet them[J].Environmental Science & Technology,2013,47(12):6681-6687.
[67]YueGuangxi,CaiRunxia,LuJunfu,et al.From a CFB reactor to a CFB boiler-the review of R&D progress of CFB coal combustion technology in China[J].Powder Technology,2017,316:18-28.
[68]BasuP.Circulating fluidized bed boilers:design,operation and maintenance[M].Switzerland:Springer,2015.
[69]Fuertes AB,AlvarezD,RubieraF,et al.Surface area and pore size changes during sintering of calcium oxide particles[J].Chemical Engineering Communications,1991,109(1):73-88.
[70]LiuH,Gibbs BM.The influence of calcined limestone on NOx and N2O emissions from combustion in fluidized bed combustors[J].Fuel,2001,80(9):1211-1215.
[71]Haji-Sulaiman MZ,Scaroni AW.The calcination and sulphation behaviour of sorbents in fluidized bed combustion[J].Fuel,1991,70(2):169-176.
[72]WinterF,WarthaC,LöfflerG,et al.The NO and N2O formation mechanism during devolatilization and combustion under fluidized-bed conditions[J].Symposium(International) on Combustion,1996,26(2):3325-3334.
[73]Yue GX,Pereira FJ,Sarofim AF,et al.Char nitrogen conversion to NOx in a fluidized bed[J].Combustion Science and Technology,1992,83(4-6):245-256.
[74]HouXiangsong,ZhangHai,YangShi,et al.N2O decomposition over the circulating ashes from coal-fired CFB boilers[J].Chemical Engineering Journal,2008,140(1-3):43-51.
[75]KwaukM,LiJinghai.Fluidization regimes[J].Powder Technology,1996,87(3):193-202.
[76]JinXiaozhong,LuJunfu,YangHairui,et al.Comprehensive mathematical model for coal combustion in a circulating fluidized bed combustor[J].Tsinghua Science and Technology,2001,6(4):319-325.
[77]李竞岌,杨欣华,杨海瑞,等.鼓泡床焦炭型氮氧化物生成的试验与模型研究[J].煤炭学报,2016,41(6):1546-1553.LiJingji,YangXinhua,YangHairui,et al.Experimental study and modeling of NOx generation from nitrogen in the bubbling bed[J].Journal of China Coal Society,2016,41(6):1546-1553(in Chinese).
[78]张楚,林郁郁,章明川.快速床动力学统一模型Ⅱ:上部稀相与下部浓相固含率的预报[J].工程热物理学报,2012,33(4):694-698.ZhangChu,LinYuyu,ZhangMingchuan.A unified model for fast fluidization dynamics—part II:prediction of upside dilute phase holdup and lower dense phase holdup[J].Journal of Engineering Thermophysics,2012,33(4):694-698(in Chinese).
[79]刘向军,赵燕,徐旭常.循环流化床内煤粉颗粒团燃烧行为理论分析[J].中国电机工程学报,2006,26(1):30-34.LiuXiangjun,ZhaoYan,XuXuchang.Theoretically studies of the coal particle cluster combustion behavior in a circulating fluidized bed[J].Proceedings of the CSEE,2006,26(1):30-34(in Chinese).
[80]Aamand LE,LecknerB.Oxidation of volatile nitrogen compounds during combustion in circulating fluidized bed boilers[J].Energy & Fuels,1991,5(6):809-815.
[81]LiJingji,ZhangMan,YangHairui,et al.The theory and practice of NOx emission control for circulating fluidized bed boilers based on the re-specification of the fluidization state[J].Fuel Processing Technology,2016,150:88-93.
