Experimental investigation of NO_x emisssion in a coal-fired utility boiler

Based on the investigation of NOx formation mechanism, a coal-fired utility boiler whose capacity is 1 004 t/h was studied. Excessive air coefficient, inclination of burner and the way of coal supply were investigated through experimental method. Resuits indicated that under the condition of same boiler efficiency and burn-off rate, the operation conditions adopting the lower excessive air coefficient, upward burners＇ inclination and pyramid coal-supply could reduce NOx emission.

Analysis of Prese nt Operating Situati on of Large Size Coal-F ired Utility Boilers

Large size utility boilers develop rapidly in China, both their reliability and economics have reached better level. The operating situations of various existing boilers on the basis of different coals are analyzed, it is held that, the notable energy imbalance of furnace exit, ever existing in the tangential firing boilers has been solved, with comparatively lower NOX emission concentration of gained. The higher NOX emission concentration and furnace slagging etc. problems existing in wall firing boilers are notable. The comprehensive analysis shows that, it is appropriate to choose lower furnace volume heat release rate and higher flame height in the type selection design of boilers, and sufficient margin should be kept in the selection of coal pulverizing mills.

INTRODUCTION TO INCONEL ALLOY 740: AN ALLOY DESIGNED FOR SUPERHEATER TUBING IN COAL-FIRED ULTRA SUPERCRITICAL BOILERS

Chinese utilities as well as those worldwide are facing increased demand for additional electricity, reduced plant emissions and greater efficiency. To meet this challenge will require increasing boiler temperature, pressure and coal ash corrosion resistance of the materials of boiler construction of future coal-fired boilers. A new nickel-based tube alloy, INCONEL^R alloy 740, is described aiming at meeting this challenge. Emphasis will be on describing the alloy＇ s mechanical properties, coal-ash and steam corrosion resistance. Microstructural stability as a function of temperature and time is addressed as well as some of the early methodology em- ployed to arrive at the current chemical composition.

NO_x emission model for coal-fired boilers using partial least squares and extreme learning machine

To implement a real-time reduction in NOx,a rapid and accurate model is required.A PLS-ELM model based on the combination of partial least squares(PLS)and the extreme learning machine(ELM)for the establishment of the NOx emission model of utility boilers is proposed.First,the initial input variables of the NOx emission model are determined according to the mechanism analysis.Then,the initial input data is extracted by PLS.Finally,the extracted information is used as the input of the ELM model.A large amount of real data was obtained from the distributed control system(DCS)historical database of a 1 000 MW power plant boiler to train and validate the PLS-ELM model.The modeling performance of the PLS-ELM was compared with that of the back propagation(BP)neural network,support vector machine(SVM)and ELM models.The mean relative errors(MRE)of the PLS-ELM model were 1.58%for the training dataset and 1.69%for the testing dataset.The prediction precision of the PLS-ELM model is higher than those of the BP,SVM and ELM models.The consumption time of the PLS-ELM model is also shorter than that of the BP,SVM and ELM models.

Correlating furnace characteristics of utility boilers with coal characteristics

1.IntroductionCoal is listed in China’s energy policy as the predominant fuelto be used for thermal power generation.It includes nearly the wholespectrum of coals that China has,ranging from anthracite to browncoal.This poses a situation to China’s utility boiler manufacturers thattheir products have to cope with all kinds of coal available.China is now producing a full range of utility boilers with ca-pacities from 35 t/h through 2000 t/h.They have successfully burnedanthracities with volatile matter greater than 7% and low grade coalswith high moisture and high ash contents.They burn bituminouscoals and lignites with satisfactory efficacy.

Neural network approach to predicting mercury emission from utility boiler

The feasibility of using an ANN method to predict the mercury emission and speciation in the flue gas of a power station under un-tested combustion/operational conditions is evaluated. Based on existing field testing datasets for the emissions of three utility boilers, a 3-layer back-propagation network is applied to predict the mercury speciation at the stack. The whole prediction procedure includes： collection of data, structuring an artificial neural network （ANN） model, training process and error evaluation. A total of 59 parameters of coal and ash analyses and power plant operating conditions are treated as input variables, and the actual mercury emissions and their speciation data are used to supervise the training process and verify the performance of prediction modeling. The precision of model prediction （ root- mean-square error is 0. 8 μg/Nm3 for elemental mercury and 0. 9 μg/Nm3 for total mercury） is acceptable since the spikes of semi- mercury continuous emission monitor （SCEM） with wet conversion modules are taken into consideration.

Feasibility Analysis on the Integrated Application of Solar Energy, Biogas, Coal-fired Boiler and Radiant Floor Heating for Rural Residence

The feasibility of adopting a balanced energy mix mode (domestic solar energy, biogas, coal-fired boiler and radiant floor heating) was proposed. Taking a typical rural residence in Zhengzhou City for example, the study through theoretical analysis and calculation showed that such a balanced energy mix is an economic way and efficient in saving energy and reducing air pollution, and elaborated the theoretical feasibility of popularizing such a heat supply mode in rural areas.

System Performance and Pollution Emission of Biomass Gas Co-Firing in a Coal-Fired Boiler

To reduce greenhouse gases emission and increase the renewable energy utilization portion in the world, the biomass gasification coupled with a coal-fired boiler power generation system is studied. It is a challenge to achieve optimum performance for the coupled system. The models of biomass gasification coupled with co-firing of coal in a boiler have been established. A comparative study of three kinds of biomass (Food Rubbish, Straw and Wood Pellets) has been done. The syngas produced in a 10 t/h gasifier is fed to a 330 MWe coal-fired boiler for co-combustion, and the co-firing performances have been compared with pure coal combustion case under the conditions of constant boiler load. Results show that co-firing decreases the furnace combustion temperature and raises the flue gas temperature for Food Rubbish and Straw, while, flue gases temperature decrease in case of Wood Pellets. At the same time NOx and SOx emissions have reduced. The system efficiencies at constant load for Food Rubbish, Straw and Wood Pellets are 83.25%, 83.88% and 82.56% when the optimum conditions of gasification and co-firing process are guaranteed.

Comprehensive evaluation for efficient development of coal-fired Industry boiler clearing

The Paper has introduced development of domesticand foreign coal-fired industry boiler and has implementedcomprehensive comparison for several substitution technologies（coal powder boiler, coal water mixture boiler, coal-fired boiler,gas-fired boiler and biomass boiler, etc.） of backward coal-firedindustrial boiler in technology, economy and environment, etc.;has evaluated comprehensive effect and adaptiveconditions of coal-fired industry boiler technology and has put forward suggestion forefficient development of coal-fired industry boiler clearing.

Combustion and Self-Desulfurization Characterization of Blended Low-Rank Coals for Improved Resource Utilization in Fluidized Bed Boilers

The co-combustion of low-rank coals through fluidized bed boiler(CFB)is an effective approach to enhance the level of resource utilization.To date,there has been a lack of investigation concerning the co-combustion kinetics and self-desulfurization characteristics of coal slime,coal gangue,and raw coal.In this study,we adopted multiple model-free and model-fitting methods to comparatively analyze co-combustion kinetics of blended coals on the basis of thermogravimetric data.Then,the sulfur balance and self-desulfurization of blended coals in the co-combustion were intensively investigated using a tube furnace set-up.The results reveal that in the presence of coal gangue in blended coals,the average activation energy(E_(a))falls within the range of 65.7 kJ/mol to 100.4 kJ/mol,as determined by four model-free methods.Conversely,in the absence of coal gangue,only the Flynn-Wall-Ozawa(FWO)and Friedman(FM)methods are deemed appropriate for calculating the average E_(a),yielding a value of 77.3 kJ/mol.The first order reaction model is confirmed to be reliable for analyzing the co-combustion kinetics of low-rank blended coals.Irrespective of the specific composition of the blended coal,a significant linear correlation exists between the Ea and the natural logarithm of the pre-exponential factor(lnA)within an extensive range of parameters.Moreover,the addition of coal gangue to the blended coal substantially enhances the self-desulfurization level,resulting in an increase from 25.7%to60.7%at 1073 K.The self-desulfurization efficiency exhibits a good linear relationship with both the mass ratio of coal gangue to coal slime and the molar ratio of calcium to sulfur.In a practical implementation,the optimal addition ratio of coal gangue is a trade-off between the self-desulfurization efficiency and the ignition capacity.

Development of 600 MW Class Coal Fired Boilers in China

This article introduces the present status anddevelopment of 600 MW class boilers in China. The statisticaldata indicate that most 600 MW generating units experiencedrelatively length" growing up" period. In this period, unitscould not operate stably , their unplanned outage times weremany and durations long, and availabilities low. On the basis oftesting and research and the summing-up of practice, it wasindicated slagging in the furnace, deviation of tine gas energy atthe exit of furnace, and overheating bursting of superheater andreheater etc, endangering the safety and economics ofoperation,main problems could be completely alleviated oravoided through design and type selection of boiler furnace andburners, coal characteristics and coal handling management,and optimization management of operation conditions etc.

新型高效除尘大折流挡板余热锅炉在高尘泥烟气余热回收中的应用

在锅炉发展的过程中,如何降低高尘泥烟气的排烟温度,进行余热回收是一个难题。因为能源紧张,冶金、石油行业的烟气余热回收一直是中国节能减排的重中之重,烟气中细小的悬浮金属化合物不但对设备造成侵蚀从而降低工作效率,还对环境造成了污染。针对烟气微小颗粒的流动及锅炉效率低,采用分析的方法找到锅炉效率低的关键点,并采取措施。研究发现,烟气中的尘泥附着在管道影响传热效率是造成锅炉整体效率低的主要问题,为沉降尘泥在锅炉交错式安装折流挡板,其结合脉冲除尘装置产生较好的效果,烟气通过折流挡板的往复流动增强湍流作用,更加有效沉降尘泥,更有利于烟气余热回收。安装的折流挡板沉降了大量的尘泥,增强了传热,脉冲装置的配合使用更加有效地提高了锅炉热效率。

某电站锅炉水冷壁泄漏案例分析

通过某电厂水冷壁焊缝开裂泄漏案例介绍,分析其裂纹产生原因,并简单提出制造过程中预防的一些措施。

低负荷下燃气‒蒸汽联合循环机组与煤气发电机组经济效益分析

马钢北区拥有1台燃气‒蒸汽联合循环发电机组和1台全烧煤气锅炉发电机组,用于平衡马钢北区高、焦、转炉煤气。为提高煤气综合利用效率,采集2台机组不同负荷下煤气消耗数据并进行分析,根据分析结果对2台机组的煤气资源进行最优分配,优化生产运行组织方式,最大可能实现有限煤气资源多发电。

CFB锅炉掺烧气化细渣技术研究进展

煤气化渣产量大、存量多,常规的填埋和堆积处理不但占用大量土地资源,而且还存在严重的污染风险和安全隐患。本文介绍了气化细渣的组成、结构和燃烧特性,综述了残碳富集、脱水干化等气化细渣预处理方法的研究进展,从气化细渣的含水率、灰分、掺烧比例及污染物排放情况等方面分析了气化细渣掺烧对循环流化床(CFB)锅炉燃烧的影响,指出CFB锅炉掺烧气化细渣具备显著的环保和经济效益,是气化细渣实现减量化、无害化和资源化利用的主要途径之一。

耦合余热回收下电站锅炉尾部烟气热能高效梯级利用系统设计

针对电站锅炉尾部烟气热能利用效率较低,梯级利用数值模拟过程与全尺度数据分析过程偏差较大的问题,设计了一种耦合余热回收下的电站锅炉尾部烟气热能高效梯级利用系统。实验结果表明,系统的最佳烟气热能高效梯级节点利用情况和热能梯级置换情况整体都保持在60%以上,采用热能阶梯式温差电站后,系统整体效率提高了约22%,证明了所设计系统的使用优越性。

电站锅炉常用的金属材料金相检测研究

电站锅炉是发电厂中重要的设备,其工作环境复杂,对金属材料的性能要求较高。而金相检测是一种常用的金属材料性能评估方法,通过分析材料的显微组织,全面分析材料相组成、晶粒尺寸、硬度等信息。基于此,针对电站锅炉中常用的金属材料进行金相检测研究,收集电站锅炉中常见的金属材料样品,如碳钢、合金钢、不锈钢等,再采用金相显微镜观察这些样品。观察结果表明:不同金属材料的显微组织存在明显差异,碳钢主要由铁素体和珠光体组成,而合金钢中含有大量的马氏体相,不锈钢具有较为均匀的奥氏体相。此外,在金相检测过程中,对样品硬度进行测试,发现不同金属材料的硬度存在差异,与其显微组织特征相关,碳钢硬度较低,合金钢和不锈钢硬度较高。

高压蒸气换热器在聚酯装置中的应用

聚酯生产所需的热量传递是通过有机热载体强制循环来完成。目前主流的导热油加热系统是将导热油直接加热,通过高温油泵进行强制液相循环,将加热后的导热油送到用热设备,换热完成后再由用热设备循环至锅炉区再加热,形成一个完整循环的加热系统。普通的燃煤锅炉的能源利用效率仅有80%~85%,未被充分利用的热量往往造成了能源浪费。通过配置耐高压换热器,利用高压水蒸气对循环的有机热载体供热,将导热油顺利地加热到325~330℃,替代厂区内原有的锅炉加热有机热载体,此方式具有换热效率高、日常维护少及运行稳定等诸多优点,可为相关的研究提供一定的借鉴。

余热梯级利用在聚酯装置炉区的应用

燃煤炉区承担着聚酯工厂各系统的供热,对企业来说,降本增效是永恒的要求。公司作为耗能重点单位,利用现有技术,深挖系统潜能,降低生产成本成为现阶段的重中之重。本文介绍了某企业基于能源双控要求,通过锅炉余热梯级利用的改造案例,可年节约原煤5159t,年节省燃料支出600多万元,研究成果可为相关企业提供参考。

燃气-蒸汽联合循环机组性能状态评估及优化技术研究

该文主要探究燃气-蒸汽联合循环机组的性能状态评估方法和优化技术。以某燃气电厂机组作为研究对象,分别选取燃气透平内效率、蒸汽轮机内效率与循环热效率、余热锅炉余热利用率等指标,对燃气轮机、蒸汽轮机、余热锅炉的性能进行评估。结果表明,燃气轮机与蒸汽轮机性能稳定,余热锅炉性能下降明显。进一步分析余热锅炉的烟气数据和水汽数据,认为蒸发器性能下降是导致余热锅炉性能下降的主要原因,在此基础上提出加装烟气过滤装置、优化过渡烟道结构等优化策略,从而使该机组性能恢复良好。