T型煤粉锅炉富氧燃烧的数值模拟

为研究采用富氧燃烧方式煤粉锅炉的燃烧特性,利用Fluent软件对一台T型煤粉锅炉的富氧燃烧过程进行了数值模拟,得到了一次风含氧体积分数变化时炉膛内温度场、速度场和烟气各组分物质的量浓度的分布.结果表明:富氧条件下整个炉膛温度水平高于空气助燃条件下;当含氧体积分数由21%增大至33%时,炉膛平均温度由1 413.2K升高为1 447.1K;当含氧体积分数增大至27%时,炉膛平均温度变化较明显,达到1 435.6K;当含氧体积分数大于29%时,炉膛平均温度变化不明显;变一次风风量富氧燃烧方式的含氧体积分数最佳范围为27%～29%.     

富氧条件下汽油机燃烧过程数值模拟与试验研究

本文采用数值模拟和试验的方法研究进气中O<,2>体积分数对汽油机燃烧特性的影响.根据湍流的分形特征,应用分形理论计算了湍流燃烧速度和质量燃烧率等.试验对一台单缸汽油机分别提供O<,2>(氧气)体积分数为21%、23%、25%、27%和29%的富氧空气,分析缸内压力及放热率.借助VB语言编制计算程序,进行了计算与试验对比分析.     

膜法富氧试验及富氧燃烧

介绍膜法富氧的原理和作者进行的富氧试验,阐明富氧燃烧的意义及工程应用的特点。     

燃高炉煤气富氧燃烧器的数值模拟

基于燃烧理论,以高炉煤气为燃料,通过燃烧计算,选定蜗壳式旋流配风器,设计一种适合高炉煤气等低热值煤气的燃烧器。用FLUENT软件进行燃烧过程的数值模拟计算。模拟结果表明,使用30%左右的富氧空气和煤气预热300℃时,燃烧温度提高,火焰中高温区面积增大,燃烧效果及经济效益最佳。     

富氧燃烧锅炉初探

介绍了不同目的的锅炉富氧燃烧技术,重点分析了膜法富氧对于锅炉性能所带来的影响,对于进一步发展膜法富氧锅炉技术和扩大应用提出了建议.     

不同富氧条件下高炉煤气和焦炉煤气燃烧数值模拟

为研究高炉煤气和焦炉煤气在不同富氧条件下的燃烧特性,以某钢厂75 t/h燃气锅炉为对象,利用数值模拟软件Fluent,选用带旋流修正的Realizablek-ε湍流模型和有限速率/涡耗的散燃烧模型,采用速度入口、压力出口、标准壁面方程、无滑移、无湍流运动边界条件,对炉内着火距离、温度和热流密度分布进行了模拟.结果 表明...     

高炉氧煤燃烧器中煤粉燃烧过程的数值模拟

本文采用颗粒相连续介质－轨道模型对同轴射流渐扩式高炉氧煤燃烧器内煤粉燃烧过程进行了数值模拟。数值模拟结果表明，同轴射流渐扩式氧煤燃烧器在适当的射流速度比条件下，可在氧煤枪出口后方诱导出回流区及低速区，有利于延长煤粉在直吹管内的停留时间，改善煤粉在热风管中加热、挥发和挥发份的着火条件，改善氧气和煤粉的混合，提高煤粉燃烧区的氧气浓度。     

强弱射流型MILD富氧燃烧器燃烧特性的数值分析

采用计算流体力学(CFD)数值模拟方法对一种强弱射流型MILD富氧燃烧器的流动和燃烧特性进行了分析.采用有限速率/涡耗散(FR/EDM)模型预测了丙烷MILD富氧燃烧过程中烟气速度场、温度场、组分体积分数分布和烟气内循环流量比等宏观特征,并与已有实验数据进行比较,验证了模型的准确性.在此基础上深入分析了MILD富氧燃烧的化学反应区结构、湍流和化学反应时间尺度等微观特征.结果表明:强烈的烟气内循环充分地稀释并预热主反应区内的反应物,减缓了化学反应速率,从而降低了火焰峰值温度,揭示了强弱射流型MILD富氧燃烧的低氧温和燃烧特征.     

Numerical simulation of pulverized coal MILD-oxy combustion under different oxygen concentrations

As an emerging clean coal combustion technology, Moderate or Intense Low-Oxygen Dilution (MILD) combustion or oxy-fuel combustion, compared with traditional coal combustion, has many advantages. However, compared with MILD combustion and oxy-fuel combustion, MILD-oxy combustion is believed more attractive. In this work, MILD-oxy combustion characteristics with oxygen concentrations from 10% to 50% are studied numerically. The results show that within a certain range, increasing the oxygen concentration is in favor of MILD-oxy combustion performance close to that of MILD-air combustion. When the oxygen concentration is higher enough, the momentum reduced by the increase of oxygen concentration has a great influence on the furnace temperature. With the increase of oxygen concentration, the radiation heat transfer is enhanced and the convective heat transfer is weakened. The increase of oxygen concentration can promote the occurrence of char gasification reaction with CO₂. In addition, MILD-oxy combustion has a large impact on CO emission.     

氢氧加湿燃烧的数值模拟

介绍了利用CHEMKIN 4.1软件中封闭的全混同性反应器模型模拟加湿情况下氢氧燃烧的方法,同时基于详细的氢氧燃烧化学反应动力学机理分析了初始反应温度、反应压力及水蒸气添加量等对氢氧燃烧的影响。模拟结果表明,初始反应温度、反应压力及水蒸气添加量等因素均会对氢氧燃烧的点火延迟时间和燃烧最高温度产生一定程度的影响,其中水蒸气添加量的变化对氢氧燃烧的最高温度及火焰传播速度的影响较为显著。这对后续在实验室中进行氢氧加湿燃烧研究可提供有益的指导。     

Numerical simulation of hydrogen combustion process in rotary engine with laser ignition system

In this paper the combustion and ignition process in the hydrogen-fueled peripheral-ported rotary engine with single and dual laser ignition systems was studied numerically. The computational method was established for the process simulation including interaction between turbulence and chemical reactions. The detailed chemical kinetic model of hydrogen combustion was used. It was shown that the ignition and combustion process in the H₂-fueled rotary engine is highly transient with specific distortion and stretching of the combustion front in the combustion chamber due to complex motion of the rotor relative to the engine housing. The single and dual laser ignition systems were simulated to compare the ignition efficiency and the rate of hydrogen burning out. The evaluation of pressure in the combustion chamber was performed and compared with the experimental data obtained for the rotary engine fueled by natural gas. It was shown that the H₂-fueled rotary engine with the dual laser ignition system has potential application in alternative automotive industry due to high efficiency and near-zero carbon-based emission.     

富氧燃烧烟气加压脱硝的实验与模拟研究

为了解决富氧燃烧烟气中NOx对CO2资源化利用的影响问题,实验研究了加压条件下鼓泡与液膜反应器中液体对NOx的吸收作用。建立了高压下NOx吸收的传质及动力学耦合模型,利用该模型对鼓泡吸收和液膜吸收进行了模拟,获得了不同压力下气液相产物的浓度,并与实验结果进行了对比。结果表明:气液相产物的实验结果与模拟结果吻合,且模型的氮元素守恒率高于90%;最佳吸收压力为1.5 MPa;吸附在反应器壁面的液膜对于NOx有较强的吸收作用,液膜的成分主要是HNO3。     

一种高强度富氧天然气燃烧器火焰特性的数值模拟

根据天然气冲天炉结构特点设计了一种富氧高燃烧强度的燃烧器并建立燃烧器燃烧的物理模型和数学模型,利用CFD软件Fluent模拟研究了不同预热温度以及不同空气预混比例对燃烧温度、火焰长度变化等的影响规律,为以后该类型燃烧器的设计提供了理论依据。     

Numerical simulation of turbulent combustion in porous materials

This paper presents one-dimensional simulations of combustion of an air/methane mixture in porous materials using a model that explicitly considers the intra-pore levels of turbulent kinetic energy. Transport equations are written in their time-and-volume-averaged form and a volume-based statistical turbulence model is applied to simulate turbulence generation due to the porous matrix. Four different thermo-mechanical models are compared, namely Laminar, Laminar with Radiation Transport, Turbulent, Turbulent with Radiation Transport. Combustion is modeled via a unique simple closure. Preliminary testing results indicate that a substantially different temperature distribution is obtained depending on the model used. In addition, for high excess air peak gas temperature is reduced and the flame front moves towards the exit of the burner. Also, increasing the inlet flow rate for stoichiometric mixture pushes the flame out of the porous material.     

同轴度对引射器性能影响的数值分析

船用燃气轮机需要安装引射器来降低红外特征,受限于机舱尺寸,引射器的主喷管和混合管往往不能同轴线布置。为了研究主喷管和混合管在非同轴线布置下对引射器的影响,本文以某燃气轮机上带有冷却孔的引射器为研究对象,采用数值模拟的方法研究了主喷管相对混合管轴线偏离±30%,±50%,±70%时引射器的性能,并且对比了冷却孔在开闭状态下的性能。结果表明：当冷却孔关闭时,主喷管向负方向偏移时压力损失系数最大提高4.3%,向正方向偏移时压力损失系数最大提高2.5%;当冷却孔开启时,偏移方向对压力损失系数没有明显影响,且引射器内部的燃气总温降低100~150 K。     

钝体燃烧的数值模拟

钝体燃烧模拟考虑湍流和燃烧相互耦合。在标准κ-ε两方程模型下分别采用非预混燃烧模型中化学平衡、稳态小火焰和瞬态小火焰模型,研究不同燃烧模型对组分、温度场以及流场分布的影响。数值模拟结果表明,上述燃烧模型模拟的结果与前人研究成果存在不同程度的差异,稳态小火焰模型优于其它模型,但模拟该燃烧器的燃烧模型尚需进一步完善。     

富氧燃烧的节能特性及其对环境的影响

本文从富氧燃烧的节能特性及其对环境的影响两方面来探讨富氧燃烧。随着氧气制备技术的低成本化,采用富氧燃烧对于当前来讲可以很好地提高燃烧效率从而达到节能的效果,同时也要注意其对环境的影响。