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.

Computational Study on Furnace Process in a Multi-burner Boiler of Pulverized Coal Fired Tangentially at Four Corners

Aiming at the optimization of the operation condition, a general numerical method for calculating pulverized coal combustion in a full scale furnace fired tangentially at four corners is adopted. “ k ε ” turbulence model is used for the gas phases and a stochastic approach based on the Lagrangian technique is used for particle phases. Two competing reactions model for the coal devolatilization and PDF (the probability density function) method for the combustion of the gas phases are employed. In the numerical simulations, assuming the air distribution of second port level is of pagoda, waist drum and uniform type. The results show that pagoda type air distribution is advantageous to ignition and smooth combustion of pulverized coal, and suitable to inferior coal combustion in practice. In the present furnace, the igniting distance at 1st and 3rd corner is longer than that at 2nd and 4th corner. The results from numerical calculations are in good agreement with those of observed in practice.

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.

Two-stage numerical simulation for temperature profile in furnace of tangentially fired pulverized coal boiler

Considering the fact that the temperature distribution in furnace of a tangential fired pulverized coal boiler is difficult to be measured and monitored, two-stage numerical simulation method was put forward. First, multi-field coupling simulation in typical work conditions was carried out off-line with the software CFX-4.3, and then the expression of temperature profile varying with operating parameter was obtained. According to real-time operating parameters, the temperature at arbitrary point of the furnace can be calculated by using this expression. Thus the temperature profile can be shown on-line and monitoring for combustion state in the furnace is realized. The simul-(ation) model was checked by the parameters measured in an operating boiler, (DG130-9.8/540.) The maximum of relative error is less than 12% and the absolute error is less than 120℃, which shows that the proposed two-stage simulation method is reliable and able to satisfy the requirement of industrial application.

Equation of Radiation Heat Transfer in Multiple Combustion Boiler Furnace of Fluidized Bed and Pulverized Coal Firing

The equation for radiation heat transfer in a multiple combustion boiler furnace with nuidized bed and pulverized coal firing is derived from direct calculation of radiation heat transfer.

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.

Discussion on Selection of Pulverizer and Moisture of Pulverized Coal for Lignite Boilers

In China,the abrasion index and the free moisture are regarded as the criteria for determining whether the medium-speed pulverizer or the fan pulverizer could be selected.Based on comprehensive studies on foreign methods for choosing the pulverizing system for lignite boilers,it is suggested that the particle size of coal,the drying time,the drying temperature and the humidity should be taken into account when measuring the free moisture of lignite,and the total moisture could also be the principle for type selection of pulverizer for lignite boilers.Furthermore,the determination of pulverized-coal moisture has great influence on the running of pulverizing systems.The actual moisture of certain pulverized coals is compared with that calculated with different methods and a feasible method for determining the moisture of the pulverized coal is suggested.

Influence of Recirculated Flue Gas Distribution on Combustion and NOx Formation Characteristics in S-CO_(2) Coal-fired Boiler

Supercritical carbon dioxide(S-CO_(2))Brayton power cycle power generation technology,has attracted more and more scholars'attention in recent years because of its advantages of high efficiency and flexibility.Compared with conventional steam boilers,S-CO_(2) has different heat transfer characteristics,it is easy to cause the temperature of the cooling wall of the boiler to rise,which leads to higher combustion gas temperature in the furnace,higher NOX generation concentration.The adoption of flue gas recirculation has a significance impact on the combustion process of pulverized coal in the boiler,and it is the most effective ways to reduce the emission of NOX and the combustion temperature in the boiler.This paper takes 1000MW S-CO_(2) T-type coal-fired boiler as the research target to investigate the combustion and NOX generation characteristics of S-CO_(2) coal-fired boilers under flue gas recirculation condition,the influence of recirculated flue gas distribution along the furnace height on the characteristics of NOX formation and the combustion of pulverized coal.The results show that the recirculated flue gas distribution has the great impact on the concentration of NOX at the boiler outlet.When the bottom recirculation flue gas rate is gradually increased,the average temperature of the lower boiler decreases and the average temperature of the upper boiler increases slightly;The concentration of NOx at the furnace outlet increases.

大型燃煤锅炉中含Na/Cl/S组分的演变与受热面结渣倾向的数值模拟

提出了一种考虑煤中含Na/S/Cl组分多步释放、气相组分相互作用、气-固反应以及盐蒸气冷凝耦合灰颗粒黏附的结焦模型,以预测炉内受热面气态碱金属组分冷凝行为、受热面结焦风险以及炉膛出口Na/S/Cl组分分布特性。结果表明:炉膛出口气态含Na组分主要以NaO_(2)、NaCl、Na_(2)SO_(4)和NaOH形式存在;最上层燃烧器至分离燃尽风(SOFA)喷口区域、最下层燃烧器至冷灰斗转角区域的水冷壁结焦风险高;炉膛出口区域后屏过热器底部颗粒黏附位置相对集中,炉内辐射式过热器结焦速率远高于气态钠盐冷凝速率,对流受热面颗粒沉积速率约是钠盐蒸气冷凝速率的3~4倍。

60 t/h煤粉预热燃烧锅炉宽负荷运行特性研究

为满足国家“双碳”目标下煤炭清洁高效利用领域的迫切需求,在工业锅炉、电站锅炉等领域开发了煤粉预热燃烧技术。煤粉先进入流态化预热燃烧器中高温改性,再进入锅炉炉膛分级配风燃烧,从而实现了煤高效、低氮燃烧,并在1台60 t/h煤粉锅炉上进行了技术验证。锅炉侧墙对冲布置了2只预热燃烧器,单只预热燃烧器设计热功率为26 MW,以烟煤为原料,在10%~100%负荷范围开展了6个不同负荷的锅炉运行特性和NOx排放特性试验研究,结果表明:该锅炉在各负荷下运行状态稳定、良好,无助燃条件下实现了10%超低负荷稳定运行;预热燃烧器各参数合理、循环状态稳定,满足锅炉宽负荷的运行要求;负荷下锅炉燃烧效率均在97%以上,10%、20%负荷下锅炉热效率大于85%,30%及以上负荷锅炉热效率均在90%以上;通过调整配风,锅炉各负荷下NO_(x)原始排放均低于50mg/m^(3)(φ(O2)=9%)。60 t/h煤粉预热燃烧锅炉的成功示范,为煤粉高效清洁灵活燃烧技术的发展和应用提供了重要支撑。

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.

粉煤炉电厂烟气颗粒物中多环芳烃的赋存特征及源解析意义

针对安徽淮南3家粉煤炉燃煤机组排放的烟气,分析了可吸入颗粒物(PM_(2.5–10)、PM_(1–2.5)、PM_(1))中多环芳烃(PAHs)的浓度和组成及PAHs单体同位素的值.研究表明,烟气颗粒物中PAHs排放浓度主要受锅炉类型、燃烧参数和大气污染控制设施等因素的影响.细颗粒物易富集PAHs,且对高分子量PAHs的富集程度更高.不同粒度颗粒物中PAHs特征比值的变化幅度较小,但对不同燃煤源排放的PAHs仍有较大的不确定性.PAHs单体碳同位素值有效区别燃煤锅炉源、生物质燃烧和车辆尾气排放源,但对于粉煤炉的不同燃烧过程指示不明显.

煤粉锅炉协同处置油泥过程中NO_(x)和SO_(x)的排放特性研究

油泥中含有大量的S、N等污染物,采用煤粉锅炉协同处置油泥时,需要考虑协同处置对NO_(x)和SO_(x)生成的影响.首先对3种油泥样品进行固定床燃烧小试试验研究,得到了油泥的燃烧速率等基本燃烧特性和NO_(x)、SO_(x)等燃烧污染物排放特性,其次通过敏感性分析和生成速率分析,结合基于误差传播的直接关系图解法建立了简化的煤粉炉协同处置油泥的NO_(x)、SO_(x)反应机理模型,包括36种组分132个反应,并耦合300MW四角切圆煤粉锅炉协同处置含油污泥的燃烧过程的数值模拟,预测了油泥协同处置量对NO_(x)与SO_(x)生成的影响.研究发现:NO及SO_(2)主要来自燃料,同时受温度、O_(2)浓度和还原性基元的影响;协同处置油泥时NO生成量的变化主要受温度影响,协同处置量为3%时,炉膛出口处NO的平均浓度低于纯煤粉燃烧;炉膛出口处SO_(2)的平均浓度随着协同处置量的增加而增加.研究结果为预测煤粉炉协同处置油泥时污染物的生成奠定基础.

工业煤粉锅炉制粉系统优化的探索与实践

以陕西延长中煤榆林能源化工股份有限公司为例,针对锅炉制粉系统煤粉细度不达标、磨煤机出口一次风管风速偏差大、煤粉进入炉膛燃烧效果差问题,对制粉系统进行了磨煤机加载力特性、分离器挡板开度特性、磨煤机出力特性等调节试验,将磨煤机出口煤粉细度按照实际燃用煤质的特性调整到合理的水平,并提供了磨煤机优化运行推荐参数的合理范围。同时,针对锅炉制粉系统调整试验过程中发现的各种问题,提出了后续设备运行维护的基本措施和改造技术路线。该方法通过现场调整、试验,查找存在问题并逐一解决,对热动力车间整体设备状态的提升有着重要的意义。

燃烧器对冲布置电站锅炉侧墙水冷壁结焦及高温腐蚀问题解决研究

在自然资源短缺的情况下,煤价也呈现出一种逐渐上升的趋势,导致火力发电厂的运营成本持续增加。在此种情况下,大部分电厂通过采购劣质煤、掺烧煤泥的方式来降低运营成本,但是却出现了锅炉水冷壁结焦、高温腐蚀问题。基于此种情况,研究以某电厂燃烧器对冲布置电站锅炉为例,首先分析造成侧墙水冷壁结焦、高温腐蚀的原因,其次,借助X射线荧光光谱、X射线衍射分析锅炉结焦、高温腐蚀机理,最后,并提出相应的解决对策。通过分析设备改造后的应用效果发现,锅炉结焦、高温腐蚀的情况得到有效缓解,达到了预期效果,在一定程度上提升了企业的经济效益与社会效益。

热动力站320t/h煤粉锅炉结焦问题的治理经验总结

针对某公司公用工程中心热动力站一期320 t/h煤粉锅炉在运行过程中出现的炉膛水冷壁和燃烧器大面积结焦问题,通过了解掌握使用煤种的特点、特性,校核炉膛主要热力特性参数,分析原燃烧器在设计、运行中存在的问题后,针对性地提出了采用降低燃烧区壁面热负荷、更换防结焦型低氮燃烧器及强化吹灰运行管理等全面系统的改造思路和方案。改造方案在停炉期间实施后,经过冷态空气动力场试验、热态调试及各种典型工况下的运行试验表明:改造后燃烧器着火及时、燃烧稳定,蒸汽参数合格,锅炉长周期运行出力得到大幅提高,燃烧器及炉膛壁面结焦问题得到了根本治理,氮氧化物初始排放浓度等各项运行经济指标均达到设计要求,为解决燃用低灰熔点榆林烟煤煤粉锅炉普遍存在的问题提供了一个成功治理的实例。

煤粉锅炉变工况NO_(x)生成及排放特性研究

电站燃煤锅炉排放的NO_(x)对环境造成了较大的影响。论文主要研究了过量空气系数、负荷、燃尽风率及煤种对炉内燃烧及NO_(x)生成的影响,总结了锅炉变工况NO_(x)排放特性研究现状,通过物理模型和数学模型成网格无关性验证和模型验证,调整锅炉燃烧工况,使燃烧过程高效、节能。

干粉煤气化装置激冷水系统的优化

介绍了干粉煤气化装置及其激冷水系统的工艺流程。通过对激冷水系统各支路阻力降的计算分析,发现原激冷水系统工艺流程存在激冷水偏流的可能和风险。通过阻力降计算结果优化了激冷水系统的工艺流程配置,再合理设置调节阀、增设喷淋水管线和冲洗水管线,从根本上解决了激冷水偏流问题。