Thermal and emission characteristics in a tangentially fired boiler model furnace

Tangentially fired furnaces are vortex‐combustion units and are intended for use as low NO formation furnaces. NO characteristics inside these furnaces depend on many parameters. The present study investigates numerically the problem of pollution in a real furnace of a 1699 MW tangentially fired boiler having 32 burners. NO formation contour maps in a tangentially fired furnace are presented. The study covered different combustion air temperature values, different fuel–air ratios and different cases of tripped burners. Available experimental measurements were used for validating the calculation procedure. The details of the temperature and NO fields were obtained from the solution of the conservation equations of mass, momentum and energy and transport equations for scalar variables in addition to the equations of the turbulence model. The equations governing the NO formation were solved to calculate the NO distribution. The simulation provided more insight on the correlation between the total NO concentration and the maximum furnace temperature and furnace average temperature. The results have shown that the furnace average temperature and NO concentration decrease as the excess air factor increases for a given air mass flow rate. As the combustion air temperature increases, furnace temperature increases and the thermal NO concentration increases sharply. The results show that the temperature distributions are significantly distorted by tripping any of the burners. The results show that tripping one or two burners either adjacent or opposite or tripping four results in regions of high temperature gases close to the walls. Heat absorptions in super‐heater and economizer are greatly influenced by combustion air temperature and excess air factor and are slightly influenced by burner tripping. Copyright © 2009 John Wiley & Sons, Ltd.     

膜法富氧局部助燃技术在煤粉锅炉上的应用

利用膜法富氧技术,在150 t/h煤粉锅炉上进行了局部增氧助燃技术的工业试验.实验表明:膜法富氧局部增氧助燃技术的应用,有效地解决了炉膛结焦和高温腐蚀问题;大渣及飞灰可燃物含量降低,提高了低负荷不投油稳燃能力;提高了锅炉热效率;降低了NOx排放量.     

工业炉燃烧方式的优化

综合分析了工业炉燃料能源化学能转换、能量传递及烟气排放过程。提出了新的燃烧方式，研究了其对燃烧温度的影响。结果发现：新的燃烧方式能使燃料能源在工业炉上得以清洁及有效利用。图10表1参7     

高效红外电阻炉的发展和特佳应用（1）

论述了高效红外电阻炉的效益、结构、改进及最佳应用。此炉比常规炉升温时节能５０％－６０％，保温时节能３０％－４０％。温度均匀度提高，有利于保证产品质量。报道了在搪瓷烧成炉、精铸烤型炉、高精铝合金淬火炉等炉型上的应用、新型设计及功效。     

Experimental investigation on the feasibility of a movable heat-insulation device

Currently, many boilers in China can not burn low rank coals and low-calorific-value gases (blast-furnace gas, converter gas, etc.) stably and/or efficiently and have a poor adaptability to frequent variation of load and fuel rank. Moreover, the temperature and pressure of the generated steam deviate a lot from the nominal value and can not meet the users’ demand. In order to resolve these problems, a microporous ceramic-board-based movable heat-insulation device is devised. The board is installed on a furnace waterwall tube and can be moved up or down during operation so as to maintain a properly high and quasi-constant temperature in the near burner zone in the case of low load or low rank fuel. The structure, working principle and feasibility of the device are introduced and analyzed. Finally, encouraging calculation and experiment results are demonstrated. The results show that the device can work safely and reliably in low-calorific-value gas fired furnaces and all kinds of stoker-based furnaces and has very good potential for improving the overall performance of a boiler in terms of the combustion stability and efficiency, the adaptability to load and fuel.     

全氢罩式退火炉内罩温度数值分析

利用CFD软件对全氢罩式炉退火热过程进行了模拟计算,得到了不同工况下罩式炉内罩的表面温度分布,根据得到的模拟结果研究了罩式炉内罩温度和热流密度的变化情况,并对退火生产中钢卷表面碳黑缺陷的产生原因进行了分析。     

Heat flux estimation in an infrared experimental furnace using an inverse method

Infrared emitters are widely used in industrial furnaces for thermal treatment. In these processes, the knowledge of the incident heat flux on the surface of the product is a primary step to optimise the command emitters and for maintenance shift. For these reasons, it is necessary to develop autonomous flux meters that could provide an answer to these requirements. These sensors must give an in-line distribution of infrared irradiation in the tunnel furnace and must be able to measure high heat flux in severe thermal environments. In this paper we present a method for in-line assessments solving an inverse heat conduction problem. A metallic mass is instrumented by thermocouples and an inverse method allows the incident heat flux to be estimated. In the first part, attention is focused on a new design tool, which is a numerical code, for the evaluation of potential options during captor conception. In the second part we present the realization and the test of this “indirect” flux meter and its associated inverse problem. “Direct” detectors based on thermoelectric devices are compared with this new flux meter in the same conditions in the same furnace. Results prove that this technique is a reliable method, appropriate for high temperature ambiances. This technique can be applied to furnaces where the heat flux is inaccessible to “direct” measurements.     

燃煤气的闭式STIG循环中气化系统能量转化效率的研究

针对燃煤气的闭式ＳＴＩＧ循环,给出气化系统能量转化效率的计算式,计算三种典型气化炉分别采用高温干法和常温湿法净化系统的能量转化效率,同时分析能量转化效率对整个循环系统效率的影响。     

Prediction of protective banks in high temperature smelting furnaces by inverse heat transfer

An inverse phase change heat transfer method has been developed for predicting the time evolution of banks covering the surface of refractory brick walls inside high temperature smelting furnaces. The presence of these banks is indispensable as they serve as a protective barrier against the highly corrosive slag, thereby maintaining the structural integrity of the furnace and prolonging its active life. The numerical model rests on the conjugate gradient solution method with the adjoint equation. It predicts banks thickness and motion relying on the thermal conditions prevailing outside the furnace and temperature measurements taken at one location inside the brick wall. Simulations are carried out to examine the effect of different parameters on the predictive capabilities of the method. Results reveal that the method remains accurate in spite of the fact that the temperature measurements inside the wall are noisy and are taken at depth of few centimetres only. An example showing how the present inverse method can be used to warn on the imminent loss of the protective bank during the operation of a smelting furnace is then provided.     

2~#PX装置加热炉炉群热效率下降原因分析及对策

分析某石化公司2#PX装置加热炉系统热效率下降的原因,介绍提高热效率的具体措施,通过更换余热系统失效热管,并建议增加加热炉对流室换热面积及改造空气预热器的方法,提高系统整体热效率,保证装置高负荷长周期经济运行。     

炼油厂加热炉综合改造及效果分析

中国石油玉门油田分公司玉门炼油化工总厂随着“短流程燃料型”加工方案的调整,加热炉运行台数由20台减少为14台,用能水平明显提高,综合能耗显著下降,但主要装置(常减压、重整、焦化装置)加热炉都是上世纪90年代设计、制造的,运行时存在排烟温度高、氧含量高、入炉空气温度低、炉内壁保温破损、炉体漏风、炉体外壁温度高、燃料消耗大、热效率低等问题.针对上述问题,利用2010年7月份检修机会,对常减压、重整和焦化装置加热炉进行了综合改造.在采取系列综合改造措施后,3套主要生产装置的加热炉平均热效率由86.92％上升到了93.76％,平均过剩空气系数由1.36降低到0.86,平均排烟温度由224.25℃降低到了124.7℃,平均炉体表面温度由77.75℃降低到了37.7℃,加热炉运行状况得以大幅改善.随着加热炉运行状况的改善,瓦斯消耗量降低、装置处理量提高,极大地改善了装置各项经济指标.     

工业催化剂及其载体焙烧设备进展

焙烧几乎是所有固体催化剂及其载体制备的最后环节。焙烧温度对催化剂的结构性质、物相、晶粒大小、表面酸性以及强度、比表面、孔分布等性质具有重要影响,并最终影响催化剂的综合性能。从实验室少量焙烧到大批量的工业生产,即从小容积、温度场均匀、浓度场均匀和间歇操作的实验室焙烧装置放大到温度场和浓度场尚不十分清晰的工业焙烧设备,有必要研究设备变化的工业放大效应。在催化剂工业生产中,有微波焙烧炉、厢式焙烧炉、回转式焙烧炉、网带式焙烧炉、流态化焙烧炉、立式焙烧炉、隧道窑、梭式窑、辊道窑等多种焙烧窑炉可供选择。厢式炉不适于连续生产,网带式炉不适于高温焙烧,对于大批量催化剂的高温焙烧往往采用隧道窑和连续式回转炉。通过炉体自身的旋转,回转炉能促使物料颗粒之间的相互混合,而隧道窑则不能;回转炉炉体不漏风,物料床层截面主体温度均匀,而隧道窑中易出现窑车下部漏风、窑车自身蓄热等问题,从而引起预热段断面的上下温差;此外,隧道窑温度分布不均匀。微波炉具有加热速度快等优点,是近年来发展较快的焙烧方式。     

3．0Mt／a重催装置余热锅炉现状及节能技术改造

兰州石化公司炼油厂3．0Mt／a重油催化裂化装置的两台余热锅炉在运行中存在烟气侧运行阻力大、排烟温度高、省煤器给水入口温度低、存在尾燃等问题。采用翅片管结构省煤器、提高助燃空气温度、改造燃烧器、布置正压防爆固定旋转式蒸汽吹灰器对余热锅炉进行节能技术改造。改造后,两台锅炉炉膛压力分别由改造前的2.8kPa和2.7kPa降到1.9kPa和1.8kPa,余热锅炉烟气侧阻力降低;锅炉排烟温度由300℃降到205℃,烟气热量利用率和锅炉热效率得到提高;增设给水预热器后,省煤器给水温度及出水温度分别提高到150℃和240℃,外取热器及油浆蒸汽发生器多产蒸汽10t/h,两台锅炉总产汽量增加了60t/h,产生效益1908.42万元。     

3D thermomechanical behaviour of solid oxide fuel cells operating in different environments

Hermetic sealing and long-term structural reliability of fuel cell stacks depend strongly on the thermomechanically induced stress–strain behaviour. These are especially affected by the environment; the fuel cell is operating in. Most of the research and development studies, as well as laboratory studies are conducted within electrically heated furnaces rather than operating in an insulated system environment. The thermomechanical comparison of them is not fully understood, yet. The present study utilises a previously developed full scale three dimensional planar type 6-cell SOFC short stack model to shed light on the thermomechanical response of high temperature fuel cells operating in system and furnace environments. The physically resolved coupled computational fluid dynamics and computational structural mechanics model has been improved, accounting for the rate dependent creep strain, as well as including the furnace domain and thermal radiation to fully describe the thermal and deformation behaviour of the stack. The non-linear elastoplastic behaviour of the metal components as a function of temperature is considered. The results are validated using creep strain data from the literature and in-house post-mortem images. The study gives an insight about the critical regions prone to failure due to creep strain operating in different environments and the long-term fuel cell behaviour. Moreover, the critical locations appear to be prone to high creep strain after 1000 h operation time.     

我国锻造工业炉的现状及发展趋势

阐述了铸造工业炉燃料构成，炉型结构，燃烧装置，余热利用，耐火材料及热工控制等方面的技术现状，以及煤炉改造及高性能锻造工业炉的发展趋势。     

高周波活塞热冲击计算与分析

本文用6150柴油机燃气温度拟合成三角形热冲击模式，作为活塞顶面的热激励源，建立了高周波三角形热冲击及集总参数导热模型，计算该活塞顶面温度响应曲线及其变化规律，以作为活塞顶面热疲劳分析和研究的基础。     

Enhancement of thermal efficiency and cost effectiveness by development of melting furnace by revamping and troubleshooting fuel‐fired furnace

Technological development of furnaces over conventional melting methods of diesel or gas‐fired furnaces is necessary. These furnaces have large amount of heat losses and hence their thermal efficiency is very low. Moreover, these furnaces do not produce good quality melt because of the chances of embedment of impurities from after‐combustion gases and agitation. The time required for melting in such furnaces is more. Also, insulation is not provided and there are heat losses which increase the time of melting. An electric resistance heating furnace is developed which overcomes all the problems associated with the fuel‐fired conventional furnace. The thermal efficiency of this developed furnace is found to increase quite drastically up to 85%, which is by about 33% more than conventional furnace; while reducing the operating cost of furnace. This benefits industry overall by profit of 70% and certainly can replace the existing conventional fuel‐fired furnaces.     

A Monte Carlo model for predicting the effective emissivity of the silicon wafer in rapid thermal processing furnaces

Advances in microelectronics led to the development of rapid thermal processing (RTP). Accurate in situ temperature measurement and control are crucial for RTP furnaces to be largely accepted in the fabrication of semiconductor chips. This paper describes an effective emissivity model based on the Monte Carlo method to facilitate radiometric temperature measurements. The results showed that for non-diffuse wafers the “true” effective emissivity (defined in this paper) should be used, instead of the hemispherical effective emissivity, to correct thermometer readings. The geometric parameters and surface radiative properties can significantly influence the effective emissivity. The numerical aperture of the lightpipe radiation thermometer and the wafer-to-shield distance may be optimized to improve the measurement accuracy.     

Thermal characteristics of an underground cold-water reservoir: Analytical and experimental studies

The thermal characteristics of an underground cold-water reservoir are investigated analytically and experimentally. An analytical solution is developed for the temperature distribution in the reservoir by assuming a linearized boundary condition at the water surface. The results are compared with the experimental measurements which have been conducted in a cistern located in the city of Yazd. Very good agreements between the analytical and the experimental results at various times during the withdrawal cycle are observed, ensuring the accuracy of the analytical solution obtained for the linearized boundary condition. The results show that a stable thermal stratification is preserved in the reservoir throughout the entire course of the withdrawal cycle. During this period, the outside temperature reaches as high as 42 °C, while cool water with the temperature varying from 12 to 13 °C is easily available from the underground water reservoir under investigation.     

电弧炉电气特性在线监测系统的研制与应用

开发了集短路试验、运行电气特性测试以及功能强大的各种电工仪表于一身的实时、高速、高精度的电弧炉电气特性在线监测系统并给出了应用实例。应用该系统可方便地进行短路试验、运行电抗测量、常用电工参数的测量与记录、多路波形显示、钢水温度测量等,可作为电弧炉专用配套系统应用于电弧炉的系统调试与运行诊断上。