循环流化床锅炉内的灰平衡模型研究

建立了煤灰为床料的 CFB锅炉内静态平衡计算模型 .模型着重研究了成灰特性、灰磨耗和退档 ,颗粒停留时间及颗粒分层等影响循环流化床灰平衡的重要因素 ,并提出了相应的计算模型 .应用模型模拟了黄姑电厂 75 t/h CFB锅炉的运行 ,研究了磨耗速率、灰成分等因素对煤燃烧后飞灰、排渣、床料的粒径分布的影响     

Experimental and model investigation on the mass balance of a dry circulating fluidized bed for flue gas desulfurization system

A moderate temperature dry circulating fluidized bed flue gas desulfurization (CFB-FGD) process was developed using rapidly hydrated sorbent. This technique has the advantages of low cost, no water consumption, and a valuable dry product CaSO₄. To keep the system operation stable, a mass balance model, based on cell model considering flow state, particle abrasion, particle residence time, particle segregation and desulfurization processes, was built to predict the system state and optimize the operating condition. Experimental studies were conducted on a pilot-scale CFB-FGD system with rapidly hydrated sorbent made from CFB circulating ash and lime (circulating ash sorbent) or coal fly ash and lime (coal fly ash sorbent). Calculated results were compared with experimental results and the relative error was less than 10%. The results indicated that feed sorbent mass, feed sorbent size, superficial gas velocity, particle abrasion coefficient and cyclone efficiency had significant influence on the mass balance of CFB system. The circulating ash sorbent was better than the coal fly ash sorbent, for providing higher desulfurization efficiency and being better for the CFB-FGD system to achieve mass balance.     

循环流化床锅炉浅床运行技术及大型化分析研究

对小容量循环流化床（CFB）锅炉浅床运行技术进行了分析总结,浅床运行方式适合于燃用褐煤及高挥发分烟煤的CFB锅炉,可降低一次风机压头和风机电耗。对于中等容量CFB锅炉,浅床运行可能会导致密相区结焦及燃烧效率降低等问题,为降低飞灰及底渣可燃物含量,需要维持足够的床层高度或风室压力。对浅床运行模式的大型化问题进行了技术分析。     

CFB锅炉内成灰特性的实验研究方法

The material balance in CFB furnace is important for the performance of the boiler.The bed inventory consists of coal ash and desulfurizing agent.In order to design properly the boiler and auxiliary,the engineers need to know the ash formation characteristics. Generally, the most reliable method to get ash formation data of a coal is to burn it in the real industrial CFB boiler. Due to the high cost and difficulties in sampling in such a test,people have to present other simple method on ash formation.The present investigation is proposing a simple laboratory test procedure to study ash formation by static combustion and sieving.Validation of the method is given.     

循环流化床锅炉飞灰含碳量的测定方法探讨

对循环流化床锅炉飞灰的烧失量和含碳量进行了对比 ,烧失量与含碳量差别很大。传统上用烧失量代替含碳量对循环流化床锅炉飞灰并不适用。本文提出用煤的工业分析方法测定循环流化床锅炉飞灰的含碳量 ,并测出循环流化床锅炉飞灰含碳量随粒径分布的变化关系。     

煤粉炉和循环流化床锅炉飞灰特性对其汞吸附能力的影响

通过分析两台容量相近的循环流化床锅炉和煤粉锅炉飞灰样品的粒径分布、表面结构特性、未燃尽碳含量、反应性和汞含量，探究两种类型锅炉飞灰特性差异及其与飞灰汞吸附能力的关系。结果表明：循环流化床和煤粉锅炉尾端除尘设备排灰口飞灰汞的含量分别为1584.0 ng/g和503.7 ng/g，其原因与飞灰粒径、未燃尽碳含量和表面特性相关。对于循环流化床锅炉，飞灰中汞含量随其粒径和反应性温度的减小而增加，随未燃尽碳含量增加而增加，且与比表面积和吸附量呈正相关关系。对于煤粉锅炉，粒径为75～53 μm的飞灰对汞吸附能力较强，未燃尽碳含量明显小于循环流化床所产生飞灰的含量，飞灰比表面积随粒径变化不大，由此导致煤粉锅炉除尘设备排灰口所取样品对汞的吸附能力远低于循环流化床锅炉相对应位置飞灰对汞的吸附能力。     

煤的成灰磨耗特性对循环流化床内物料平衡的影响

循环流化床燃烧条件下煤的成灰磨耗特性是影响床内的流化特性和锅炉整体性能的重要因素之一 .利用静态燃烧然后冷态流化实验方法 ,可以得到给煤的成灰及磨耗参数并提出煤种的本征成灰概念 .在此基础上建立稳态的 CFBC冷态灰平衡模型来研究流化床内物料的粒径分布规律 .分析了流化风速、分离器效率和煤灰的磨耗系数对飞灰、排渣和床料的粒径分布的影响 .     

Pilot Development of Polygeneration Process of Circulating Fluidized Bed Combustion combined with Coal Pyrolysis

A pilot polygeneration process of a 75 t h^–1 circulating fluidized bed (CFB) boiler combined with a moving bed coal pyrolyzer was developed based on laboratory‐scale experimental results. The process operation showed good consistency and integration between boiler and pyrolyzer. Some critical operating parameters such as hot ash split flow from the CFB boiler to the pyrolyzer, mixing of hot ash and coal particles, control of pyrolysis temperature and solid inventory in the pyrolyzer, and pyrolysis gas clean‐up were investigated. Yields of 6.0 wt‐% tar and 8.0 wt‐% gas with a heating value of about 26 MJ m^–3 at 600 °C were obtained. Particulate content in tar was restrained less than 4.0 wt‐% by using a granular filter of the moving bed. Operation results showed that this pilot polygeneration process was successfully scaled up.     

600MW超临界CFB锅炉耐火材料应用探索

根据四川白马电厂600 MW超临界循环流化床锅炉运行情况,结合循环流化床锅炉循环系统中炉膛、回料器、外置床、灰控阀等重要设备工况特点,分析了各部位耐火材料作用行为和特性要求。运行6年的实践证明:大型循环流化床CFB锅炉设备合理选择耐火材料,可有效解决金属受热面磨损造成爆管,克服金属材料高温变形、耐磨性能差、不耐高温等问题,保证了机组安全稳定运行。大型循环流化床CFB锅炉对耐火材料的性能提出了更高要求,有待进一步分析和研究耐火材料在超临界CFB锅炉中的应用,提高机组耐磨性能和运行稳定性。     

降低循环流化床锅炉飞灰含碳量的因素分析

循环流化床锅炉的飞灰含碳量是锅炉燃烧工况好坏的直接反映 ,其对锅炉的热效率的影响是很大的 ,它还直接影响着粉煤灰的综合开发和利用 .在对云天化循环流化床锅炉的生产实验研究中 ,分析了影响循环流化床锅炉飞灰含碳量的各种因素 (床温、煤质煤粒、一次风、二次风、床压和旋风分离器效率等 ) ,通过实验研究找到了降低循环流化床锅炉飞灰含碳量的具体而又行之有效的操作方法 ,以指导实际生产 .     

燃煤循环流化床锅炉燃烧控制及传热分析

讨论了循环流化床(CFB)锅炉的传热机理、燃烧控制以及实现灰、热平衡的方法。系统分析了灰、热平衡和燃烧控制对锅炉负荷及效率的影响。提出了CFB锅炉的优化操作、长周期经济运行应采取的措施和方法。在传热分析中,着重分析了传热机理,灰、热平衡及灰浓度对传热的影响。在燃烧控制中,介绍了床温、床压、风量及一二次风配比、返料温度、返料量、料层压差、炉堂压差的控制与调整。     

Characteristics of clinker formation in a circulating fluidized bed boiler firing Korean anthracite

To shed light on the causes of clinker formation during the initial operation period of the Tonghae circulating fluidized bed (CFB) boiler, which uses Korean anthracite as fuel, the properties of ash, sand and limestone particles and the mixtures of each gradient have been characterized. The clinkers formed in the loopseals and the fluidized bed ash cooler (FBAC) of the CFB boiler were also characterized by analyzing the composition, the surface phenomena and the crystal structure of the clinkers. As a result, the black clinker was found to come from the sand particles and the composition of the white clinker was found to be similar to that of ash particles. The cause of the clinker formation in the FBAC proved that ash was sticking to molten or sintered phases in the high temperature regions in the boiler. On the other hand, the composition of the ash changed with the particle size, showing an enrichment of Fe₂O₃ as the particle size decreased. Also, the ash particles between 75–100 μm contained more than 11% CaO which resulted in low initial deformation temperature of the particles. So it is possible to explain that the amount of Fe and Ca in the fine particles of the ash plays a crucial role in the formation of agglomerates in the CFB boiler.     

燃煤循环流化床锅炉N_2O排放影响因素分析

阐述了CFB锅炉燃烧过程中N_2O的产生、消解机理,分析了燃料特性、床温、过量空气系数和煤中的矿物质成分等诸多因素对CFB锅炉N_2O排放的影响。分析了生物质与煤混合燃烧,炉膛后再燃,在CFB锅炉中添加催化剂以及反向分级燃烧等新型低N_2O燃烧技术,为CFB锅炉低N_2O排放技术指明了研究方向。     

超低排放燃煤机组硒的迁移转化及飞灰对其富集特性

采用微波消解法和氢化物发生-原子荧光光谱法考察了9台超低排放在役机组硒迁移转化规律,探究了循环流化床（CFB）和煤粉炉（PC）机组飞灰特性差异对硒吸附能力的影响。燃烧后煤中硒几乎全部呈现挥发态,底渣中残留量极低。与浓度归一化和质量分布法相比较,相对富集系数法可以客观地评价燃煤副产物中硒的富集能力,两类机组中硒均主要富集于飞灰中。CFB较低炉膛温度和添加CaO可以降低入炉煤中硒释放比例并增强飞灰对硒的吸附能力,故其底渣和飞灰中硒的富集程度均高于PC,导致脱硫石膏中硒富集程度低于PC。飞灰对硒的吸附量随比表面积或孔容积增大而增大,但随粒径或孔径增大而减小。CFB飞灰中未燃尽碳含量高、形状不规则、表面粗糙且存在较多蜂窝状孔隙,导致其对硒的富集程度高于PC飞灰。     

煤中矿物组分在流化床燃烧过程中的转化

循环流化床锅炉炉内的燃烧及传热与炉内床料的状态密切相关,而炉内床料主要是由燃煤含有的矿物组分经过燃烧、爆裂和磨耗过程形成的．分析和总结了在循环流化床锅炉中温燃烧条件下,煤中矿物组分化学反应的一般情况,总结了循环流化床锅炉灰渣的化学组分与组分的存在形态有利于煤粉锅炉灰渣的特点．     

影响BT-75/4.4-M循环流化床锅炉床温因素分析

循环流化床锅炉的床温是循环流化床锅炉最重要的控制参数，它直接影响着整个锅炉的热效率和脱硫效率，从云天化股份有限责任公司的循环流化床锅炉的实际运行出发，分析了影响循环流化床锅炉床温的各种因素，其中主要因素有煤质、煤量、煤粒粒径、一次风、二次风、脱硫剂、循环灰量和床层高度等，据此选择出适合云天化循环流化床锅炉的床温，并利用返灰量来自动调节控制锅炉的床温。     

Study on design of Huadian oil shale-fired circulating fluidized bed boiler

On the basis of the physical and chemical performance of Huadian oil shale and the design experience of Huadian 65 t/h oil shale-fired circulating fluidized bed (CFB) boiler operation, this paper introduces several main characteristics of oil shale, such as platy structure, high volatile and Ca/S content, and low ignition temperature, which are relevant to the design of CFB boiler, and analyses key design technologies of large-scale oil shale-fired circulating fluidized bed boiler. The design principles of large-scale oil shale-fired CFB boiler are suggested: (1) to adopt a II-shape configuration natural circulation mode with medium-temperature cyclone with downward gas exhaust, reliable antiwear technology and self-desulfurization technology; (2) to determine a circulating ratio of 6, hot state superficial air velocity of 5–6 m/s, combustion portion of about 0.5–0.6 in dense phase zone, and air velocity at the nozzle hole of air cap of 50–60 m/s; (3) to adopt an igniting system with hot gas generator below distributor plate and oil guns as auxiliary ignition device above distributor plate, and fluidized bed ash cooler retrieving the heat taken by hot slag. Lastly, the design scheme of 420 t/h superhigh pressure oil shale-fired CFB boiler is put forward and the general configuration and technical data are given at the end of this paper.     

粒径对福建无烟煤在CFB锅炉中燃尽的影响

建立了福建无烟煤细颗粒燃烧模型,计算了其在容量35 t/h循环流化床锅炉炉膛内的燃尽时间和一次通过炉膛的停留时间,分析了不同粒径煤颗粒在不同燃烧温度和不同烟气流速时在CFB锅炉内的燃尽时间和停留时间的变化差异. 实验研究了福建无烟煤粒径对飞灰碳含量的影响及燃尽的影响. 结果表明,细煤颗粒的燃尽时间与停留时间均随粒径增大而增长,但燃尽时间增幅更明显,颗粒一次通过炉膛完全燃尽的临界粒径约为0.15 mm;粒径越大的颗粒其停留时间和燃尽时间对烟气流速和燃烧温度变化越敏感;无烟煤入炉粒径明显影响CFB锅炉飞灰含碳量,选用粒度为3~8 mm的偏粗颗粒为宜.     

循环流化床锅炉SO_2超低排放技术研究

针对循环流化床锅炉污染物生成量较低的特点,分析了锅炉SO_2生成量的影响因素,不同脱硫工艺的优缺点,结合试验研究结果和工程应用实例提出了循环流化床锅炉实现SO_2超低排放的技术。结果表明:循环流化床锅炉SO_2生成量取决于煤的硫分中可燃硫所占比例、煤灰中CaO等碱金属氧化物含量和锅炉运行参数,运行参数中床温影响最大;通过优化锅炉运行参数降低SO_2生成量,炉内干法高效脱硫和烟气脱硫相结合的深度脱硫技术可以实现SO_2超低排放的目标,并具有更高的调节灵活性和运行可靠性;烟气脱硫工艺的选取上,CFB-FGD半干法脱硫工艺相对于石灰石-石膏湿法脱硫工艺更具有经济优势。     

Fundamentals of coal topping gasification: Characterization of pyrolysis topping in a fluidized bed reactor

Coal topping gasification refers to a process that extracts the volatiles contained in coal into gas and tar rich in chemical structures in advance of gasification. The technology can be implemented in a reactor system coupling a fluidized bed pyrolyzer and a transport bed gasifier in which coal is first pyrolyzed in the fluidized bed before being forwarded into the transport bed for gasification. The present article is devoted to investigating the pyrolysis of lignite and bituminite in a fluidized bed reactor. The results showed that the highest tar yield appeared at 823 to 923 K for both coals. When coal ash from CFB boiler was used as the bed material, obvious decreases in the yields of tar and pyrolysis gas were observed. Pyrolysis in a reaction atmosphere simulating the pyrolysis gas composition of coal resulted in a higher production of tar. Under the conditions of using CFB boiler ash as the bed material and the simulated pyrolysis gas as the reaction atmosphere, the tar yields for pyrolytic topping in a fluidized bed reactor was about 11.4 wt.% for bituminite and 6.5 wt.% for lignite in dry ash-free coal base.