煤粉锅炉高温受热面的吹灰

在现代化的火电站中,锅炉机组的受热面广泛采用蒸汽吹灰。水冷壁、屏式过热器和对流受热面的吹灰都已建造了现代化结构的吹灰器,足以保证可靠和有效的除灰。在锅炉设计时,锅炉的宽度取决于现有吹灰器喷咀头伸出的最大长度。国外各专业化的公司正在研究和制造结构可靠的吹灰器,其喷     

旋笛式声波吹灰器清洁锅炉受热面技术应用

针对流化床锅炉尾部受热面积灰,进行了原因分析,对比选择了旋迪式声波吹灰器,阐述了应用技术方案,并对安装前、后的技术数据进行对比,说明锅炉受热面声波吹灰清洁技术应用成功,值得借鉴。     

国外锅炉声波吹灰新技术

吹灰器是锅炉等设备的重要附属装置,其性能的好坏将直接影响设备的经济和安全运行,传统的吹灰器主要有蒸汽吹灰器和水力吹灰器,这两种方法都必须向锅炉内引入无用的介质,且必须严格按照操作规程,否则将使锅炉受热面受到损害;同时传统吹灰器的机构及传动机构在使用时,都存在许多无法解决的问题,尤其是对大空间的设备。     

锅炉各受热面吹灰作用的对比研究

为优化运行性能，通过清洁因子变化对锅炉主要运行参数影响的性能计算，得到了锅炉不同部位受热面的吹灰作用种类和大小，可作为现场指导吹灰优化运行的依据。不同部位受热面的吹灰作用因受热面位置、受热面种类和大小的不同而异，其重要性也不同。位于烟气流程起始点和蒸汽流程终点的受热面是吹灰优化运行的重点。图13表3参3     

超超临界塔式炉半辐射区优化吹灰的研究

基于热平衡和传热原理建立超超临界塔式锅炉半辐射、半对流高温受热面的污染监测模型。依据电厂受热面进、出口烟温测点及机组运行实时数据,通过热力计算得出受热面灰污变化规律,并分析灰污系数的影响因素。经过在国内某1 000 MW超超临界塔式炉进行大量的吹灰前后对比试验,验证了灰污监测模型的正确性和适用性。结合吹灰经验,提出了合理的吹灰方案,对于锅炉吹灰系统的优化运行具有实际指导作用。     

基于灰污状态监测的600MW超临界锅炉吹灰试验研究

对燃煤电站锅炉的受热面进行按需吹灰成为当前吹灰工作的热点,介绍了在某600 MW超临界机组上开发的锅炉受热面灰污状况在线监测系统,列举了全程吹灰方式和优化吹灰方式的对比试验结果。利用监测系统实现选择性吹灰,可以在保证吹灰效果的前提下有效降低吹灰蒸汽损耗,提高锅炉运行经济性,防止吹灰不当造成的管壁过度磨损。     

华电贵港电厂超临界锅炉再热汽温长期偏低的分析与对策

对华电贵港电厂超临界锅炉运行中存在的再热汽温长期偏低问题进行了深入分析,得出其主要原因为燃用煤灰分含量高,加之锅炉尾部受热面吹灰器选型不合理,导致再热器受热面管壁积灰严重而使再热器内蒸汽温升不足.提出了将水平烟道及竖井烟道内再热器受热面使用的脉冲吹灰器更换为伸缩式蒸汽吹灰器,配合改进运行调整技术的解决对策.经对水平烟道吹灰器实施改造,以及改进运行调整技术后,切实将末级再热器内蒸汽温升提高到接近设计值.     

基于小波分析的电站锅炉受热面灰污增长预测模型的研究

受热面灰污增长预测模型是研究吹灰优化方案的前提,分析了受热面灰污增长简化理论模型的基础上,基于小波变换的特征提取方法和ARMA(p,q)时序模型分析,建立锅炉受热面灰污增长综合预测模型。该模型无需额外投资,通过对电厂已有的实时数据进行分析和特征提取,便能准确评价和预测受热面的灰污状态。经某电厂省煤器灰污增长预测实例表明,该模型预测结果与实际状况相符,从而能为吹灰优化提供指导。     

燃煤锅炉受热面灰污监测与吹灰优化

提出了一种锅炉受热面灰污监测与吹灰优化方法。该方法利用神经网络建立锅炉清洁受热面换热模型,在此基础上运用非线性动态规划技术进行受热面吹灰周期的优化。在扬子石化公司热电厂#8锅炉上进行了现场测试,结果表明所提出的方法是有效的。     

锅炉智能吹灰优化系统的优化实施

正电站锅炉受热面的积灰污染不仅使锅炉运行热效率降低,严重时将导致机组降负荷运行或停机。目前大容量电站锅炉各受热面均配有不同形式的吹灰器,但是吹灰模式不合理,不仅使吹灰的总体经济性低下,而且过于频繁的吹灰会对受热面造成损坏,缩短吹灰装置本身的使用寿     

插入式程控声波吹灰技术

研制了一种用于电厂燃煤锅炉清除灰尘的插入式程控声波吹灰器,从工业应用效果来看,该声波吹灰器除灰效果好,有效降低了锅炉的烟道阻力和排烟温度,显著提高了锅炉热效率;同时,由于声波吹灰器放置烟道内,工作时对外部工作环境几乎没有影响。     

燃煤锅炉吹灰过程的熵产分析

电站燃煤锅炉运行中对受热面进行吹灰,要经历一系列不可逆过程,出现各种熵产,从热力学第二定律出发,分析电站锅炉吹灰过程的熵产,建立了吹灰蒸汽减压熵产、吹灰蒸汽混合熵产、吹灰蒸汽传热熵产、吹灰蒸汽排烟熵产以及吹灰器电机熵产的计算模型.利用某台燃煤锅炉的现场数据进行了实例计算,结果表明:同一个受热面吹灰所产牛的各种熵产在数值...     

基于人工神经网络的电站锅炉积灰实时监测系统

针对燃煤电站锅炉对流受热面积灰,提出了一种基于人工神经网络的积灰实时监测方法:利用受热面清洁吸热量和实际吸热量定义灰污特征参数;通过电厂现有的DAS系统得到的温度、压力和流量等参数可获得大量样本点;建立神经网络模型并进行训练.在燃用神华煤的某300 MW锅炉上进行了试验.结果表明:实测吸热量与预测吸热量的最大误差不超过10%,平均误差为3%左右.该方法可准确预测锅炉对流受热面的积灰情况.     

声波吹灰器和蒸汽吹灰器的经济性比较

锅炉受热面积灰长期以来一直是困扰用户头疼的问题,采取不同的吹灰方式,整体效益就会有很大差别,本文主要阐述声波吹灰器和蒸汽吹灰器的经济性比较。     

浙江某制药厂有机热载体燃油锅炉积灰原因探讨

针对浙江某制药厂应用厂内生产维生素E时的副产品油于有机热载体燃油锅炉,但引起受热面严重积灰的情况,从副产品油的成分、性质进行了研究.采用X-荧光光谱仪和煤灰成分分析方法分析了积灰的灰渣成分,用电感耦合等离子体发射光谱(ICP-AES)法分析了燃油的微量元素含量,对锅炉受热面积灰的种种可能原因进行了探讨.结果表明,积灰的主要原因并非通常所认为的燃油中的V、Na、S含量高所引起,而可能是副产品油中含有较多的Al、Si或催化剂粉末和燃烧工况不好所致.该研究对合理使用该副产品油和解决应用于燃油锅炉受热面积灰严重的问题提供了指导和参考.     

Influence of phosphorus on ash fouling deposition of hydrothermal carbonization sewage sludge fuel via drop tube furnace combustion experiments

Phosphorus effect on ash fouling deposition produced during combustion process of sewage sludge solid fuel is a very important factor. Previous studies have only focused on decrease of the ash melting temperature and increase of slagging and sintering by phosphorus content. Therefore, research regarding combustion fouling formation and its effect on temperature reduction of deposit surface by phosphorus content is insufficient. Ash fouling is an important factor, because ash in the combustion boiler process deposits on the surface of heat exchanger and interferes with heat exchange efficiency. In particular, temperature reduction of heat exchanger surface via fouling should be considered together with fouling deposition, because this is related to the heat exchanger efficiency. Synthetic ash, phosphorus vaporization, and drop tube furnace experiments were performed to investigate effect of phosphorus on ash fouling formation and temperature reduction of deposit surface under combustion condition. Phosphorus was highly reactive and reacted with ash minerals to produce mineral phosphate, which promoted ash fouling deposition during the combustion experiments. In contrast, the occurrence of sintering on deposited fouling resulted in formation of a large hollow structure, which alleviated the temperature reduction on the deposit surface. Phosphorus content had a substantial correlation with fouling deposition behavior and influenced reduction in the surface temperature of the heat exchanger, because it led to generating low temperature mineral phases.     

一种新型可变导热管传热与控制温度机理分析与实验

首次提出了一种新型可变导热管换热装置，用于增压沸腾流化床发电系统中出灰管的冷却与温度控制。分析与实验表明：在出灰管内灰渣流动不稳定，即外界加热负荷或者冷却条件显著变化时，热管的工作温度几乎不变，能够控制在要求的范围内；热管工作温度随充气量增大而增高，但控制温度特性没有明显改变；与常规热管不同，可变导热管内蒸汽温度沿冷凝段轴向显著变化，蒸汽凝结受到了抑制，热管传热量有所减少。     

吹灰器在锅炉生产中的应用

为了达到锅炉长、安、稳、满、优运行的目的,吹灰器在锅炉上正得到普遍的应用,随着社会科技的进步,吹灰器的制造技术也在不断提高发展,近几年吹灰器的发展和各种吹灰器在我厂锅炉上的应用。     

Strength development at low temperatures in coal ash deposits

At temperatures below approximately 1900°F, ash particles formed in coal-fired energy systems are relatively hard and not prone to sticking to system surfaces. However, if the ash collects on a surface not exposed to a shearing gas flow such as the downstream side of a heat exchanger or the surface of a hot-gas filter, the deposit can develop enough strength over a period of minutes to days so that it becomes difficult to remove, in some cases growing to sizes that impede the flow of gas. This paper presents data from ongoing measurements of the significance of ash and gas composition, deposit temperature, and time on the rates of strength development in simulated low-temperature ash deposits. Preliminary results of surface composition and particle-size distribution analyses of the ash, including submicron material, are also presented to explain the possible mechanisms of strength development.     

Heat transfer in ash deposits: A modelling tool-box

The objective of this paper is to review the present state-of-the-art knowledge on heat transfer to the surface of and inside ash deposits formed in solid fuel-fired utility boilers, and-based on the review-to propose models for calculation of heat transfer, e.g. in deposition models. Heat transfer will control the surface temperature of the deposit, thereby influencing the physical conditions at the deposit surface, e.g. if the surface is molten. The deposit surface conditions will affect the deposit build-up rate as well as the removal/shedding of deposits: molten deposit may lead to a more efficient particle capturing, but may also flow down the heat transfer surfaces.

The heat transfer parameters of prime interest are the convective heat transfer coefficient h, the effective thermal conductivity of the deposit k_eff, and the surface emissivity ε of the deposit. The convective heat transfer coefficient is a function of flow characteristics, and can be calculated using different correlation equations, while the other two parameters depend on the deposit properties, and can be calculated using different structure-based models.

The thermal conductivity of porous ash deposits can be modelled using different models for packed beds. These models can be divided into two major groups, depending on the way they treat the radiation heat transfer, i.e. the unit cell models and the pseudo homogeneous models. Which model will be suitable for a particular application depends primarily on the deposit structure, i.e. whether deposit is particulate, partly sintered or completely fused.

Simple calculations of heat transfer resistances for deposits have been performed, showing that major resistances are in the heat transfer to the deposit (by convection), and the heat transfer through the deposit (by conduction). Very few experimental data on the thermal conductivity of ash deposits, especially at high temperatures where radiation is important, are found in the literature. Although the structure of the deposit is essential for its thermal conductivity, most of the measurements were done on crushed samples. The results obtained using different models were compared with the experimental data published in Rezaei et al. [Rezaei, Gupta, Bryant, Hart, Liu, Bailey, et al. Thermal conductivity of coal ash and slags and models used. Fuel 2000;79:1697–1710.], measured on crushed coal ash samples. Although errors of the predictions were very high in most cases, two models were proposed as suitable for heat conductivity calculations, i.e. the Yagi and Kunii model for particulate deposits, and the Hadley model for sintered and fused deposits.

This literature study showed the need for a wide range of experimental data, which would help in evaluating and improving the existing thermal conductivity models. Also, it is necessary to formulate a more accurate model for the thermal conductivity of solid mixtures, in which potentially important sources of errors can be identified.