Numerical Simulation of High Temperature Air Combustion Flames Properties

High temperature air combustion (HTAC) is an attractive technology of saving energy and controlling environment. The mathematical models of turbulent jet flame under the highly preheated air combustion condition are conducted in the paper. The mixture fraction/probability density function model is employed. The results show that the maximum flame temperature is decreased, the temperature in the HTAC furnace is more uniform than that in the conventional furnace, and the NO x emission is low. The numerical results are partially validated by some experimental measurements.

Numerical simulation of high temperature air combustion in aluminum hydroxide gas suspension calcinations

The high temperature air combustion(HiTAC) process in gas suspension calcinations(GSC) was studied by using a CFD software FLUENT that can simulate the three-dimensional physical model of GSC with the k-epsilon turbulent viscous model, PDF non-premixed combustion species model, P1 radiation model, thermal and prompt NO pollution model. The simulation vividly describes the distributions of the temperature, velocity and consistency fields. Finally, the optimal operation conditions and igniter configuration of particular fuel combustion are obtained by analyzing and comparing the simulation results. And the emission quantity of NOx, CO and CO2 deduced from computation can play a role as reference. These optimal and estimated values are beneficial to practical operation.

The Experimental Study on Regenerative Heat Transfer in High Temperature Air Combustion

For the purpose of decomposing the processing gases CF4 from semiconductor manufacturers, ceramic honeycomb regenerative burner system is suggested by using the principle of HTAC. A simulated high temperature air combustion furnace has been used to determine the features of HTAC flames and the results of the decomposition of CF4. The preheat air temperature of it is above 900℃. The exhaust gas released into the atmosphere is lower than 150℃. Moreover, the efficiency of recovery of waste heat is higher than 80%, the NOx level in exhaust gas is less than 198 mg/m3 and the distribution of temperature in the furnace is nearly uniform. The factors influencing on heat transfer, temperature profile in chamber and NOX emission were discussed. Also some CF4 can be decomposed in this system.

Numerical Simulation of Combustion Characteristics in High Temperature Air Combustion Furnace

The influences of air preheating temperature, oxygen concentration, and fuel inlet temperature on flame properties, and NOx formation and emission in the furnace were studied with numerical simulation. The turbulence behavior was modeled using the standard k-ε model with wall function, and radiation was handled using discrete ordinate radiation model. The PDF （probability density function） /mixture fraction combustion model was used to simulate the propane combustion. Additionally, computations of NOx formation rates and NOx concentration were carried out using a post-processor on the basis of previously calculated velocities, turbulence, temperature, and chemical composition fields. The results showed that high temperature air combustion （HiTAC） is spread over a much larger volume than traditional combustion, flame volume increases with a reduction of oxygen concentration, and this trend is clearer if oxygen concentration in the preheated air is below 10%. The temperature profile becomes more uniform when oxygen concentration in preheated air decreases, especially at low oxygen levels. Increase in fuel inlet tempera- ture lessens the mixing of the fuel and air in primary combustion zone, creates more uniform distribution of reactants inside the flame, decreases the maximum temperature in furnace, and reduces NOx emission greatly.

Numerical Simulation on Pulverized Coal Combustion and NO_x Emissions in High Temperature Air from Circulating Fluidized Bed

High temperature air combustion is a prospecting technology in energy saving and pollutants reduction. Numerical simulation on pulverized coal combustion and NOx emissions in high temperature air from circulating fluidized bed was presented. The down-fired combustor, taken as the calculation domain, has the diameter of 220 mm and the height of 3000 mm. 2 cases with air staging combustion are simulated. Compared the simulation results with experimental data, there is a good agreement. It is found that the combustion model and NOx formation model are applicable to simulate the pulverized coal combustion and NOx emissions in high temperature air from circulating fluidized bed. The results show that there is a uniform temperature profile along the axis of the down-fired combustor. The NOx emissions are lower than those of ordinary pulverized coal combustion, and the NOx emissions are 390 mg/m3 and 352 mg/m3 in Case 1 and Case 2, respectively. At the range of 300-600 mm below the nozzle, the NO concentration decreases, mainly resulting from some homogeneous reactions and heterogeneous reaction. NO concentration has a little increase at the position of 800 mm below the nozzle as the tertiary air supplied to the combustor at the position of 600 mm below the nozzle.

Investigation on Combustion Characteristics and NO Formation of Methane with Swirling and Non-Swirling High Temperature Air

Combustion characteristics of methane jet flames in an industrial burner working in high temperature combustion regime were investigated experimentally and numerically to clarify the effects of swirling high temperature air on combustion.Speziale-Sarkar-Gatski(SSG) Reynolds stress model,Eddy-Dissipation Model(EDM),Discrete Ordinates Method(DTM) combined with Weighted-Sum-of-Grey Gases Model(WSGG) were employed for the numerical simulation.Both Thermal-NO and Prompt-NO mechanism were considered to evaluate the NO formation.Temperature distribution,NO emissions by experiment and computation in swirling and non-swirling patterns show combustion characteristics of methane jet flames are totally different.Non-swirling high temperature air made high NO formation while significant NO prohibition were achieved by swirling high temperature air.Furthermore,velocity fields,dimensionless major species mole fraction distributions and Thermal-NO molar reaction rate profiles by computation interpret an inner exhaust gas recirculation formed in the combustion zone in swirling case.

An Experimental Study on High Temperature and Low Oxygen Air Combustion

High temperature preheated and diluted air combustion has been confirmed as the technology, mainly applied to industrial furnaces and kilns, to realize higher thermal efficiency and lower emissions. The purpose of this study was to investigate fundamental aspects of the above-mentioned combustion experimentally and to compare with those in ordinary hydrocarbon combustion with room temperature air. The test items were exhaust gas components of CO, NOx, flame shape and radical components of CH, OH and C2,which were measured with gas analyser, camera and ICCD(Intensified Charged - Coupled Device) camera. Many Phenomena as results appeared in combustion with the oxidizer, low oxygen concentration and extremely high temperature air, such as expansion of the flammable limits, increased flame propagation speed, it looked so strange as compared with those in existing combustion technology. We confirmed that such extraordinary phenomena were believable through the hot-test experiment.

蓄热炉HTAC技术应用与节能减排效果的分析研究

以目前国内高效节能的蓄热式加热炉为研究对象,开展了HTAC高温低氧燃烧技术在蓄热式加热炉上应用与效果分析。HTAC技术与空气高温预热的有效统一应用,可有效降低蓄热式加热炉烟气中NOx的排放浓度,同时缩短了烟气-燃烧过程中的换向时间,具有明显的燃料节能效果。HTAC技术的研究与应用,为蓄热式加热炉今后的节能减排发展提供了探索思路和有关途径。

HTAC的关键技术及其高效低污染特性分析

热循环再生燃烧系统是高温空气燃烧技术的核心，主要由热交换器、燃烧器、快速切换阀组成。计算了空气、烟气在陶瓷换热器小孔中的换热系数、阻力及换热器的总传热系数；介绍了可实现燃料分级的燃烧器的结构，并分析了其空气动力特性和火焰特性；讨论了高温低氧燃烧的稳定性问题，预热空气的节能效果，及低ＮＯｘ 生成特性。

高温低氧空气燃烧(HTAC)技术在我国冶金炉窑中的应用

简述了我国冶金工业开发应用高温低氧燃烧(HTAC)技术的基本情况,分析了该技术在冶金工业中的应用特点,阐明了该技术在冶金工业应用中进一步完善与提高的主要内容,对冶金工业炉窑实现高效、洁净燃烧具有一定的现实意义。

蜂窝体蓄热式HTAC技术在加热炉上的应用

介绍了蜂窝体蓄热式高温空气燃烧 (HTAC)技术在邯钢中板厂 2号加热炉上的应用和效果。燃料消耗降低 2 0 %以上 ,从而减少废气排放量 。

HTAC辐射管在燃气真空热处理炉中的应用

概要介绍了HTAC辐射管技术 ,并阐述了其结构和特点 ,以及蓄热式辐射管燃气真空炉结构和特性。

蓄热式(HTAC)燃气辐射管燃烧器研制开发

本文论述了将高温空气燃烧技术应用于燃气辐射管燃烧器加热装置 ,已研制出W型和U型蓄热式(HTAC)燃气辐射管燃烧器并经不断实验改进推出了定型产品 ,分析和介绍了新型 (HTAC)燃气辐射管燃烧器的工作原理和设计结构与技术性能。蓄热式燃气辐射管燃烧器具有热效率高、节能、表面温度分布均匀、使用寿命长 ,CO2 和NOx排放量低和工作运行柔性好等优点。

蓄热式(HTAC)燃气辐射管燃烧器在连续退火炉上的应用

论述了蓄热式(HTAC)燃气辐射管燃烧器在广东佛山南方广恒钢铁公司镀锌板生产线连续退火炉上的应用情况。生产线生产应用表明,退火炉燃烧系统采用蓄热式燃气辐射管燃烧器比使用常规辐射管燃烧器不仅在节能、环保方面具有优势,而且在炉温均匀性和炉温的可调节性能方面有很大优越性。

高温低氧燃烧(HTAC)中的反应工程问题

从冶金反应工程学角度 ,论述了高温低氧燃烧技术的应用原理及基础理论 ,重点讨论了烟气余热回收和低NOx

基于响应面法的U型辐射管HTAC燃烧优化研究

蓄热式高温空气燃烧技术(HTAC)是20世纪80年代兴起的一种新型燃烧技术,具有能量利用效率高,污染物排放低的特点。文章以油田广泛使用的水套加热炉U型辐射管为研究对象,开展基于响应面数学分析法的U型辐射管蓄热式燃烧优化及工程应用研究。分析了辐射管内污染物排放浓度、温度场随助燃空气预热温度、过剩空气系数、一二次风分级比的变化规律,优化得到了最优的操作参数。通过优化分析后可得:相比传统条件,优化操作参数下的炉子热效率提高了9.35%,一氧化氮的排放浓度降低了32.3%,具有重要的节能减排意义。

HTAC辐射管在燃气真空热处理炉中的应用

概要介绍了HTAC辐射管技术 ,并阐述了其结构和特点 ,以及蓄热式辐射管燃气真空炉结构和特性。

深井酸性浸水煤层风干氧化自然发火特性分析

为探究深井酸性浸水煤层风干氧化自然发火的特性,选取陕西省某矿煤样,利用氧化模拟试验系统,对预氧化及浸水风干煤样和原煤样进行程序升温试验,对比分析了两者的耗氧量以及CO、CO 2、CH 4的产生量,进而分析这几种不同情况下煤样的氧化自燃特性。结果表明,酸性条件下浸水风干的煤样耗氧量最小,说明该煤样在氧浓度低时容易发生氧化自燃;酸性条件下浸水风干的煤样CO、CO 2、CH 4的产生量最大,说明该煤样发生氧化自燃的危险性越大。总之,当煤体处于高地温、弱酸性浸水风干条件下发生煤体氧化自燃的危险性最大,研究结论可为矿井高产高效和安全生产提供一定的指导。

HTAC模块化立式镁还原系统的研发

近年来我国炼镁行业得到迅速发展,各种新工艺和新技术层出不穷。HTAC模块化立式镁还原系统是集优质、高产、低耗和低碳于一身的高新节能减排技术装备,与传统还原方式相比较,该系统具有降低燃料消耗、强化还原效率、改善作业环境和提高产品质量等特点。

水冷壁贴壁气氛测试与防止高温腐蚀对策研究

针对燃用高硫煤的机组低氮燃烧方式下锅炉水冷壁高温腐蚀问题,调研了采用旋流燃烧器的锅炉水冷壁发生高温腐蚀的区域,选取W火焰燃烧、对冲燃烧锅炉进行水冷壁贴壁气氛测试,分析了运行氧量、燃烧器配风方式等对水冷壁贴壁气氛及高温腐蚀的影响。结果表明:燃用高硫煤的锅炉水冷壁贴壁处CO体积分数大多高于10000μL/L,O_(2)含量均小于1%,水冷壁贴壁处为较强的还原性气氛,水冷壁面临高温腐蚀风险。将燃烧优化调整和贴壁风改造相结合,可降低水冷壁贴壁处CO的浓度,抑制高温腐蚀。