PDA research on a novel pulverized coal combustion technology for a large utility boiler

In this paper, a new technology for a tangential firing pulverized coal boiler, high efficiency and low NO_x combustion technology with multiple air-staged and a large-angle counter flow fuel-rich jet (ACCT for short) is proposed. To verify the characteristics of this technology, experiments of two combustion technologies, ACCT and CFS-1 (Concentric Firing System-1), are carried out under a cold model of a 1025 t/h tangential firing boiler with a PDA (particle dynamics anemometer). The distributions of velocity, particle concentration, particle diameters and the particle volume flux of primary air and secondary air are obtained. The results show that the fuel-rich primary air of ACCT can go deeper into the furnace and mix with the main flow better, which means that the counter flow of fuel-rich jets in ACCT can realize stable combustion, low NO_x emission and slagging prevention.     

电站锅炉热管空气预热器优化设计数学模型

提出了电站锅炉热管空气预热器优化设计的数学模型 ;将预热器最低管子壁温的控制条件引入函数矢量 ;对最优化技术在热管空气预热器设计中的应用方法和特点作了说明     

A new framework for modeling coal devolatilization and combustion in boiler furnaces

This paper presents a new framework for the modeling of coal‐fired boiler furnaces. The input required for the model is the ultimate analysis of a coal sample. The model accounts for devolatilization followed by gas‐phase combustion. The devolatilization model used in this work is taken from published literature with slight modifications to match the numerical predictions with experimental measurements. This work also develops a reactor network model for simulating the performance of boiler furnaces. For the seamless integration of kinetic models of coal devolatilization and combustion with furnace numerical model, the thermochemistry data of several hypothetical and intermediate species involved in devolatilization chemistry are evaluated in the form of 14 coefficient National Aeronautics and Space Administration polynomials. The capability of the model for predicting the furnace temperature and product composition is demonstrated by simulating a single‐zone model. Copyright © 2017 John Wiley & Sons, Ltd.     

Modelling of combustion performances and emission characteristics of coal gases in a model gas turbine combustor

In recent years, gas mixtures are being used as alternative fuels in combustors. These gas mixtures are obtained by different methods. For instance, coal gasification and carbonization as coal have the largest reserves among fossil fuels. Gas mixtures obtained via coal gasification and carbonization are called water gas, generator gas, town gas and coke oven gas. These fuels contain various gases. As a result of this, heating values of fuels are also different. Therefore, combustion performances and emission characteristics of these fuels need to be investigated. In this study, combustion performances and emissions including CO, CO₂ and NO_X of water gas, generator gas, town gases, coke oven gas and methane were numerically investigated in a model gas turbine combustor. The numerical modelling of turbulent nonpremixed diffusion flames has been performed in this combustor. Mathematical models used in this study involved the k–ε model of turbulent flow, the PDF/mixture fraction model of nonpremixed combustion and P‐1 radiation model. A CFD code ANSYS Fluent was used for all numerical investigations. Temperature distributions of axial and radial directions were determined. A NO_X post‐processor was used for the prediction of NO_X emissions from the gas turbine combustor. Modelling was performed for 60 kW thermal power and different equivalance ratios (i.e. Ф = 0.91, Ф = 0.77 and Ф = 0.67). The studied type 1 model gas turbine combustor was modelled for Ф = 0.91 equivalance ratio. Then, Other equivalance ratios were analysed for type 2 model gas turbine combustor. The effect of dilution air on combustion performances and emission characteristics was also investigated. It is concluded that the coke oven gas, the town gas I, town gas II and the water gas are appropriate for usage as alternative fuel, whereas the generator gas is not suitable for gas turbine combustors. Copyright © 2013 John Wiley & Sons, Ltd.     

Simulation of the combustion process for a CI hydrogen engine in an argon-oxygen atmosphere

Hydrogen combustion in a noble gas atmosphere increases the combustion chamber temperature, and the high specific heat ratio of the gas increases the thermal efficiency. In this study, nitrogen was replaced by argon as the intake air along with pure oxygen to supply the engine. The objectives of this study are to determine the effects of different engine parameters on combustion and to analyse the emissions from hydrogen combustion in an argon-oxygen atmosphere. This research was conducted through simulations using CONVERGE 2.2.0 software, and the YANMAR engine NF19SK model was used to determine the basic parameters. Changing the injector location affects the pressure and temperature in the combustion chamber. With increasing compression ratio, the pressure increases more rapidly than the temperature. However, combustion at high compression ratios decreases the maximum heat release rate and increases the combustion duration. Hydrogen combustion at ambient temperatures below 1200 K follows the Arrhenius equation.     

切圆锅炉煤粉燃烧过程的数值研究与工业测试

为了了解额定蒸发量为130t/h的煤粉锅炉热效率偏低,水冷壁常发生结焦现象的原因,对锅炉进行了冷态空气动力场以及热工综合测试,并应用κ－ε－g气相湍流燃烧模型与煤的双辉反应热解模型对炉流动,燃烧以及传热过程进行了数值计算。冷态与热态的数值计算结果与测试结果相吻合。其结果表明：炉膛内空气过纱数偏小导致锅炉热效率偏低;同一标高的4个燃烧器喷出的气流速度相差较大,使气流在人形成的实际切圆偏离炉膛中央,导致火焰刷壁,水冷壁结焦。     

Three dimensional modeling of pulverized coal combustion in a 600 MW corner fired boiler

IntroductionThe developments relative to coal combustion havebeen performed into a general purpose 3D code namedESTET under quality assurance, and used to modelcomplex turbulent reactive flows. In the case ofindustrial boilers we can assume a no-slip conditionbetween gas and particles which is the case for the mostpart of the furnace, except possibly in the near field ofthe burners. With such an assumption, the equations for apafticle-gas fixture with a mean density can be written.The combu…     

Numerical simulation of the combustion processes in a W‐shaped boiler furnace under different operating conditions

Numerical simulations of gas–solid flows, heat transfer and gas–particle turbulent combustion have been conducted for a three‐dimensional, W‐shaped boiler furnace. The gas–particle flow, distributions of temperature and concentrations of gaseous constituents, distributions of the rates of heat release, burnout rates of coal particles, and formations of volatiles have been predicted. The results indicate that a steady high‐temperature zone is formed under the arch of the W‐shaped flame boiler, this zone would be of benefit to the ignition and carbon burn‐out and suggest that the W‐shaped flame boiler is suitable for burning low‐quality coals and can operate well under different operating conditions for full and partial loads. Copyright © 1999 John Wiley & Sons, Ltd.     

Numerical analysis on combustion process and sodium transformation behavior in a 660 MW supercritical face-fired boiler purely burning high sodium content Zhundong coal

CHEMKIN software was used to optimize the reaction mechanism of sodium in flue gas to study the influence of targeted design for purely burning Zhundong (ZD) coal on boiler characteristics. Then, the optimized 32-step elemental reaction was combined with CFD software. An eddy-dissipation concept model considering detailed chemical reactions was used to simulate the transformation behavior of sodium-containing substances. The combustion characteristics of the 660 MW face-fired boiler under various loads were also simulated. The field distribution in the furnace and the migration path of sodium along the track of pulverized coal particles were obtained. The results show that the interference between each burner in the furnace is small at the BMCR load, and the phenomenon of “wind wrapping fire” is distinctly clear. The temperature at furnace outlet is approximately 970.98 °C. At a low load, the combustion in the furnace is stable, and the temperature at the furnace outlet reaches the design value. The sodium present in ZD coal is involved in the reaction after it is released in the form of Na and NaCl. Sodium is present in different forms in the main burner zone, mainly NaCl (67%), NaOH (12%), Na (9%), and Na₂SO₄ (7%). The forms of sodium at the furnace outlet are NaCl (50%), Na₂SO₄ (37%), Na₂Cl₂ (9%) and NaHSO₄ (4%). A small amount of Na₂SO₄ is formed by NaHSO₄ reaction in the main burner zone. It then reacts to form NaSO₄, wherein NaHSO₄ is formed by path 2. Na₂SO₄ is mainly generated in the burnout zone through path 1, and paths 2, 3, and 4 are hardly observed. The findings of this research can provide reference for the design of a purely fired ZD coal boiler and further studies on slagging observed on the heating surface.     

电站锅炉燃烧优化技术的发展与应用

系统地分析了电站锅炉燃烧优化技术的现状，针对锅炉燃烧优化存在的问题，提出了电厂实施闭环控制的可行性和必要性，并对燃烧优化闭环控制系统的功能和实施关键点进行了介绍。该技术在电厂的应用具有推广价值。     

煤粉炉的燃烧分析与燃烧器改造

通过对煤粉锅炉的燃烧分析，从运行角度提出了降低锅炉飞灰可燃物的途径及改进措施，供相关运行人员参考。     

燃煤电站锅炉NOx排放的控制措施

基于我国燃煤电站锅炉NOx排放的实际情况,在对影响其NOx排放各因素进行分析的基础上,细化了低氧燃烧、空气分级燃烧、低NOx燃烧器和燃料分级燃烧技术在我国电站锅炉的应用,指出锅炉设计中应尽可能选用切向燃烧方式,将再燃技术应用于降低燃用低挥发分煤的固态排渣电站锅炉设计和改造中以进一步降低NOx排放并满足国家标准的要求,锅炉运行中尽量减小各喷口风粉量的偏差,合理组织沿炉膛水平方向和高度方向(倒梯形、缩腰形等)的分级燃烧实现降低NOx排放的最佳效果.     

链条炉中劣质煤燃烧的分析

本文根据链条炉的燃烧特性，对燃煤的适应性要求，分析讨论了劣质煤在链条炉中的燃烧技术，并就末煤型无烟煤的燃烧提出改进措施。     

超临界W火焰锅炉燃用劣质燃料燃烧优化研究

针对W火焰锅炉运行中热效率偏低问题,对燃用的烟煤、石油焦、越南无烟煤等主要煤种开展配煤掺烧,以降低燃料成本、提高锅炉效率。从燃用煤质适应性分析、W火焰锅炉燃烧过程数值模拟和混煤掺烧优化试验3方面,研究了石油焦和越南无烟煤不同掺混比例下热解和燃烧过程特性,制定了掺烧策略并通过燃烧过程模拟研究和掺烧优化试验找到了合适的配煤掺烧方法,解决了锅炉效率低、飞灰含碳量较高、锅炉排烟温度高等问题,实现了节能降耗、提高经济效益的目的。     

Numerical investigation of influence of homogeneous/heterogeneous ignition/combustion mechanisms on ignition point position during pulverized coal combustion in oxygen enriched and recycled flue gases atmosphere

It is expected that pulverized coal combustion will continue to play a major role in electricity generation for the foreseeable future. Oxy-fuel coal combustion is actively being investigated, as alternative to conventional pulverized-coal combustion, due to its potential to easier carbon dioxide sequestration. This paper presents experimental and numerical analysis of ignition phenomena in oxy-fuel conditions. A modification of standard sequential coal combustion model is proposed. The new model is developed following the criteria for the particle ignition mechanism as the function of surrounding conditions. The implemented model was validated based on ignition point position obtained from the drop tube facility experiments in various O₂-N₂ and O₂-CO₂ conditions. The obtained numerical results showed a much better agreement with the experimental results when compared with the simulations performed with the default FLUENT sub-models for coal particle ignition/combustion, thus enabling a quantitative determination of pulverized coal flame ignition point position using numerical analysis.     

Experimental and numerical analysis of oxy‐fuel combustion in a porous plate reactor

The present work focuses on studying experimentally and numerically the oxy‐fuel combustion characteristics inside a porous plate reactor towards the application of oxy‐combustion carbon capture technology. Initially, non‐reactive flow experiments are performed to analyze the permeation rate of oxygen in order to obtain the desired stoichiometric ratios. A numerical model is developed for non‐reactive and reactive flow cases. The model is validated against the presently recorded experimental data for the non‐reacting flow cases, and it is validated against the available literature data for oxy‐fuel combustion for the reacting flow cases. A modified two‐step oxy‐combustion reaction kinetics model for methane is implemented in the present model. Simulations are performed over wide range of operating oxidizer ratios (O₂/CO₂ ratio), from OR = 0.2 to OR = 0.4, and over wide range of equivalence ratios, from φ = 0.7 to φ = 1.0. The flame length was decreased as a result of the increase of the oxidizer ratio. Effects of CO₂ recirculation amount on the oxy‐combustion flame stability are examined. A reduction in combustion temperature and increase in flame fluctuations are encountered while increasing CO₂ concentration inside the reactor. At high equivalence ratio, the combustion temperature and flame stability are improved. At low equivalence ratio, the flame length is increased, and the flame was moved towards the reactor center line. Copyright © 2015 John Wiley & Sons, Ltd.     

Modelling of the process of coal dust combustion in a cyclone furnace

This study presents the concept of a cyclone furnace for coal dust oxy-fuel combustion and gasification.The results of numerical calculations for the combustion and gasification processes were also presented.     

先控技术在电站锅炉燃烧优化中的应用

分析了电站锅炉燃烧优化应用的数个典型案例,介绍了电站锅炉燃烧优化的应用环境、优化内容与相应优化技术的特点,针对应用效果,总结了经验教训,可为燃烧优化技术的应用提供参考.     

关于影响煤燃烧固硫反应的主要因素及其机理的研究进展

燃烧过程中的脱硫是锅炉脱硫工艺的重要组成部分之一 ,已被广泛应用于各种流化床锅炉和煤粉炉中。为开发低成本、高效率的燃煤固硫技术 ,世界各国学者进行了大量的实验和机理性的研究。本文对这方面的研究进展做了总体回顾 ,并在前人研究的基础上提出了关于燃烧过程中固硫化学反应机理研究的发展趋势。     

440t/h循环流化床锅炉燃烧数值模拟研究

数值模拟是研究工程气固多相流中辅助试验方法的一种强有力的工具,本文采用数值模拟方法,对东锅DG440/13.7 -Ⅱ2型循环流化床锅炉的燃烧进行了研究,计算分析了炉内的流动、温度分布情况,对锅炉的优化设计和运行提供有益的指导.