耐热铸钢在循环流化床锅炉中的应用

循环流化床燃烧技术是国内外公认的一种洁净煤燃烧技术。循环流化床锅炉具有燃料适应性广、可燃烧矸石和煤泥等劣质燃料、脱硫成本低、污染物排放少等独特优势,是国家政策鼓励发展的项目。自20世纪80年代中期以来,我国循环流化床燃烧技术发展迅速,已成为世界上循环流化床锅炉数量最多、应用最广泛的国家。     

循环流化床锅炉布风板的焊接

0　前　　言循环流化床锅炉具有对燃料适应性好 ,有害气体排放量低 ,燃烧效率高 ,负荷变化范围大 ,调节特性好等优点 ,自它问世以来在世界各主要工业化国家得到了迅速的发展。流化床锅炉的运行特点决定了流化床锅炉设计结构和制造的特殊性。炉膛底部的布风装置是流化床燃烧系统的主要部件之一 ,是流化床锅炉的心脏。布风装置结构和尺寸是否合理直接决定了流化床内物料的流化质量 ,从而影响锅炉的点火、运行、燃烧、负荷特性以及锅炉的安全性和经济性。 5 0ＭＷ及以下当量等级的循环流化床锅炉的布风板 ,在结构上大多设计为钢性结构。在制造…     

循环流化床锅炉风帽材料的选用

自20世纪80年代以来,新型节能环保锅炉--循环流化床锅炉发展迅速,这种锅炉具有可燃劣质煤、易于脱硫和燃烧后产生的灰渣有很好的综合利用价值等独特优势.目前,我国已运行35 t/h～1 025 t/h不同容量等级的循环流化床锅炉2 000多台,约占电力行业锅炉总台数的1/3.     

自动焊技术在循环流化床锅炉制造中的应用

循环流化床燃烧技术是最近二十多年来发展起来的清洁煤燃烧技术，也是目前商业化程度最好的清洁煤燃烧技术。特别是燃用高灰份低挥发或高硫份等其他燃烧设备难以适应的劣质燃料方面以及低负荷要求较高的调峰电厂和负荷波动较大的自备电站中，循环流化床锅炉是最佳选择，是当前公认的燃煤技术的重大创新，受到世界各国普遍重视。中国是国际上少数几个以煤为主要能源的国家之一，发展高效、清洁的循环流化床锅炉，具有长远的战略意义。     

循环流化床部分技术在链条炉排上的应用

主要介绍应用循环流化床技术中的循环部分,回收链条炉排下落下的细小燃料及小颗粒未完全燃烧的灰渣和除尘器下落的飞灰进行二次燃烧。以减少机械未完全燃烧损失,增加锅炉热效率。     

浅谈小型自备热电项目中循环流化床锅炉的控制系统

通过介绍循环流化床锅炉的基本结构和运行特征,分析了循环流化床锅炉的控制特点,并结合工程实际提出了循环流化床锅炉的控制任务及实现方法.     

短周期螺柱焊工艺研究

循环流化床锅炉（CFB）是上世纪80年代发展起来的高效率、低污染和综合利用良好的燃煤技术。我公司与ALSTOM公司合作,引进其关键技术,开发了国内首台13．5万、15万及30万kW等大型循环流化床锅炉。与常规锅炉相比,循环流化床锅炉增加了高温物料循环回路部分,还增加了底渣冷却装置。     

循环流化床锅炉膜式水冷壁管屏防磨喷焊工艺

循环流化床锅炉管屏局部磨损问题日益突出,严重影响了锅炉的运行和使用寿命,如何提高管屏的耐磨性已成为循环流化床锅炉制造的新课题。具体介绍了氧乙炔火焰粉末合金喷焊膜式水冷壁管屏防磨工艺,该工艺有效地解决了循环流化床锅炉管屏局部磨损问题。     

循环流化床锅炉设计中的磨损问题

循环流化床锅炉的磨损问题一直是锅炉设计中应考虑研究、解决的重要问题;这个问题处理的好坏,直接影响到锅炉的安全稳定运行.     

440t/h循环流化床锅炉钢结构防腐蚀措施

从设计和施工方面论述了某台440t/h循环流化床锅炉钢结构的防腐蚀措施,对电站锅炉产品具有一定的参考及应用价值.     

CO2气体保护焊短路过渡过程的闭环实时控制

为了减少CO2气体保护短路过渡焊的飞溅,本文提出了短路过渡过程的闭环实时控制思想并进行了试验研究。在熔滴与熔池发生短路及液体小桥爆断这两个最容产生飞溅的时刻,利用大功率电子关元件切换焊接回路外串电阻的方法及时降低焊接回路中的电流。在前一时刻维持较低电流至溶滴与熔池充分接触,在后一时刻维持较低电流至熔滴过渡完毕,该方法能有效地抑制由瞬时短路造成的大颗粒飞溅和由电爆炸产生的细颗粒飞溅,实现了CO2气体保护焊短路过渡过程的闭环实时控制。     

Synthetically quantitative evaluation function of characteristic parameters on CO_2 arc welding process

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阳极焙烧炉结构仿真与优化

采用计算流体力学、计算传热学和计算燃烧学的原理和模型。在ＡＬＰＨＡ２５０工作站上编程计算,得到了阳极焙烧炉燃烧室内的流场、温度场和浓度场,并通过多次数学模拟提出了结构优化的方案,使流场和温度场有了明显的改善,并将焙烧温度提高了１３Ｋ,这将奶利提高阳极质量的提高产率。     

Which are the right test conditions for the simulation of high temperature alkali corrosion in biomass combustion?

The use of renewable energy sources for the generation of electricity has gained much interest in recent years. Biomass has the potential of being a CO₂ neutral energy source that could provide a significant proportion of the ever‐increasing energy demand. The easiest and most straightforward utilization of the energy content of biomass is direct combustion. The thermal energy of the biomass released in the combustion process is utilized by heating water or steam to produce electricity or heat or both (CHP). Whereas the heat production requires only modest temperatures in the water or steam circuit, producing electricity with high efficiency is not possible without high steam parameters (temperature and pressure). The heat market being quite saturated, the economic potential is in the electricity market. High heat transfer surface temperatures coupled with biomass fired steam generators have resulted, however, in serious corrosion of the heat transfer surfaces, especially in the hottest section of the convection superheaters. The type of corrosion found in biomass boilers is not encountered in fossil fuel fired boilers and the mechanism causing it is not fully understood. The development of new alloys that could withstand these harsh environments would benefit tremendously if the test conditions in the laboratory tests could be chosen so that they adequately resemble the corrosion environment in real boilers. Currently the high corrosion rate is believed to be caused by gaseous KCl that condense on the heat transfer surfaces. While KCl is certainly found in the corroded superheater tubes and probably has an important role in the corrosion reactions with the alloy, the formation of KCl on the cooled surface can also be heterogeneous. In this paper a discussion on the effect of alkali hydroxides, especially KOH, is presented. Biomass fuels have normally a high content of alkali metals and a low content of sulfur and chloride. The excess alkali will produce alkali hydroxides in the combustion environment. Alkali hydroxides then react with CO₂ in the flue gases to form carbonates as the flue gases are cooled. The reaction with CO₂, is however, very temperature dependent. The equilibrium being completely on the K₂CO₃ side with a gas temperature below 700 °C and completely on KOH side with a gas temperature above 900 °C. The hottest superheaters are normally located in the area where the flue gas temperature is 850°C–1000 °C. This makes KOH condensation on the tubes possible and subsequent heterogeneous reactions with HCl, SO₂ and CO₂ in molten phase forming KCl, K₂SO₂ or K₂CO₃. Although KOH is not thermodynamically stable at typical tube surface temperatures, a continuous flux condensing from the flue gases results in a corrosion environment on the tube where its activity has to be taken into account. Therefore it is suggested that KOH, either in gaseous or molten phase should be included in the laboratory test environments used for the testing of alloys for biomass combustion applications.     

铝合金脉冲MIG焊接熔滴过渡行为的声发射信号时频域表征

通过在线检测铝合金脉冲MIG焊接过程的结构负载声发射信号,研究熔滴过渡模式和行为的时频域表征.结果表明,熔滴过渡声发射信号波形以及熔滴过渡声发射事件的有序性和周期性可以反映脉冲MIG焊接过程熔滴过渡的稳定性和周期性.随着脉冲频率和焊接热输入的增大,熔滴过渡模式由短路过渡转变为射滴过渡,过渡熔滴体积得到逐步细化,表现出递减的声发射能量释放特征.当熔滴过渡为短路过渡模式时,熔滴过渡声发射信号的频域范围较宽,且较为集中在高频部分;当熔滴过渡为射滴过渡模式时,熔滴过渡声发射信号的频率分布范围更窄,且集中在低频部分.随着熔滴过渡模式由短路过渡模式逐渐转变为射滴过渡模式,由熔滴过渡引入的能量变化呈现出先减小再增大的趋势.     

自身预热式燃气辐射管的数值研究

采用 FLUENT商用软件对自身预热式辐射管内的流动、传热和燃烧过程进行了二维数值模拟.研究了内套管与燃烧室出口的相对位置以及助燃空气的一次风与二次风的比例对火焰长度、辐射管温度的影响.结果表明,当增加套管和燃烧室出口的距离时,火焰长度有所增加,辐射管外壁温度、套管平均温度和烟气平均温度有所增加.当增大二次风比例时,火焰长度增加,辐射管外壁温度却减小.计算结果为自身预热式辐射管的开发与优化提供了参考数据.     

Application of fluidization technology in productions of cemented carbides

The fluidization technique has advantages in rapid and high-efficiency heat transfer. Application of fluidization technology can significantly improve the productivity and product performance in the cemented carbide industries. This technique has become an attractive research topic within the issue of green and low-carbon technologies. Aiming at better understanding the principles of fluidization, in the present paper we demonstrate three typical cases of liquid–solid fluidized crystallization, bubbling bed combustion synthesis and reduction carbonization production. From these samples, we study the factors which play an important role in the fluid dynamics, fluidized state of materials and reaction thermodynamics during the process of cemented carbide production. The solutions and mechanisms of the practical problems such as the fluidized state of ultrafine particles, critical opening percentage of the distribution plate and adherent effect in multilayer bubbling bed are proposed. Moreover, the potential applications and prospects of the fluidization technology in the field of cemented carbides are presented.     

从不同的控制方式中探索短路过渡CO2焊接的飞溅问题

本文的目的是寻找减少CO_2 短路过渡焊飞溅的途径。本文研究了三种控制方法,即电流波形控制法、脉动送丝法和联合控制法。通过试验发现CO_2焊时短路过渡有两种类型:正常短路与瞬时越路。在正常短路与瞬时短路两种过程中均能产生飞溅。上述这三种控制方法中,前两种短路过程都能在一定程度上减小飞溅,而联合控制法几乎不产生瞬时短路,则使得飞溅最低。     

CO2半短路过渡焊电弧电压自寻优智能控制

针对细丝短路过渡焊,采用以实现最高短路过渡频率为目标的自寻优模糊控制,可以使电弧电压与唯一设定值焊接电流形成优化匹配获得最高短路过渡频率,达到稳定熔滴过渡、减少飞溅和改善成形的目的.但试验发现这一控制策略用于半短路过渡焊,则无论电流选多大,电弧电压常维持在20V左右,所焊焊缝熔宽窄,余高大,熔深浅.显然,对于半短路过渡焊的电弧电压仍采用以实现最高短路过渡频率为寻优目标的控制策略是不够全面的.针对这一情况,研制了一种以可编程控制器(PLC)为核心器件,通过自主开发软件自动实现对半短路过渡焊电弧电压寻优的智能控制.系统以实现较高短路频率和较长燃弧占空比为复合寻优目标,对电弧电压进行优选法和变步长法分段自寻优,寻优后的电弧电压与设定的焊接电流形成优化匹配,获得稳定的半短路过渡过程.     

短路过渡CO2焊电信号的小波滤波

利用傅里叶级数变换对CO2焊短路过渡过程的电信号特点进行了分析,指出短路过渡过程的电信号的频率分量包含了多种频率的谐波信号,既有短路过渡本身固有的低次谐波,还有短路过渡本身固有的高次谐波和高频干扰信号.应用软阈值小波滤波的方法对CO2焊普通短路过渡和波形控制短路过渡的电信号进行了处理和研究.结果表明,选择适当的波形数据处理方法对CO2焊短路过渡过程的研究具有重要意义.