不同煤种下循环流化床灰渣特性的试验研究

在一台 0 .5MW的循环流化床燃烧炉上对 4种不同煤种分别进行燃烧试验 ,对燃烧产生的灰渣的分析结果表明了煤种特性如挥发分、灰分和含碳量等对循环流化床燃烧过程的灰渣形成及其排放特性有很大影响 ,并获得了煤中挥发分、灰分及含碳量对底渣粒径及其含碳量、飞灰粒径及其含碳量、飞灰份额及燃烧效率等影响特性 ,对循环流化床锅炉的设计和运行有一定的指导意义。     

链条炉排锅炉分层燃烧技术应用

宝石机械公司5台SHL20—1．27／300链条炉排锅炉，原来使用煤闸板式给煤燃烧装置，它是由煤斗、煤闸板、弧形挡板组成。煤从锅炉煤斗依靠煤碳的重量溜入．经过煤闸板挤压后。煤层结实密集的堆积在链条炉排上面，大小煤块在煤层中无序分布，密实的煤层阻碍着空气与煤碳的充分接触，造成部分煤碳缺氧燃烧，燃烧不尽，而部分煤层出现风口、火垅。不均匀燃烧现场非常普遍，降低了煤碳的燃烧效率，致使煤碳炉渣的含碳量偏高，飞灰黑度和排烟黑度居高不下，锅炉出力不足，煤种适应性差，炉排漏煤量大．锅炉效率低下。     

分层燃烧与非倍变级调速的配套使用

一、链条锅炉存在的问题１．煤层通风阻力大,布风不均匀,风量过大２．灰渣含碳量高,漏煤损失大３．锅炉出力达不到设计要求４．工人劳动强度大,工作环境差二、分层燃烧与非倍变级调速电机配套使用简介针对链条锅炉运行中存在的问题,桑尼克绿洲公司在链条锅炉安装分层...     

分层燃烧装置技术在链条炉排上的应用

将分层燃烧装置技术应用在链条锅炉上,解决了进入链条炉排上横断面的煤颗粒不均匀的问题,降低锅炉灰渣含碳量,提高锅炉热效率。     

基于数值模拟的链条锅炉煤层燃烧分区特性分析

链条锅炉大颗粒煤的层燃过程与煤粉燃烧差异很大,为了对燃煤链条锅炉煤层燃烧特性和机理进行深入分析,本文应用二维稳态层燃模型对链条锅炉燃烧过程进行了模拟计算,并与实验结果进行了比较。对比发现模拟计算值与实验值符合较好,说明模型能准确反映床层的燃烧特性。同时对不同煤种的水分析出线、挥发分析出线、焦炭氧化区、焦炭气化区和灰渣区进行分析对比,发现不同煤种燃烧分区的差异性与煤质特性及燃烧工况等因素有关系。     

FLUENT中煤粉燃烧飞灰含碳量数值模型的改进

为了提高FLUENT软件对电站煤粉锅炉飞灰含碳量的预测精度,推导了考虑灰层扩散阻力的焦炭缩核燃烧模型,基于FLUENT软件提供的"多表面反应模型"框架,结合用户自定义函数技术对其自带的焦炭燃烧模型进行了改进。然后对某1 025 t/h电站锅炉分别采用自带和改进的焦炭燃烧模型进行模拟,并和测试结果进行了对比。结果表明:自带模型由于忽略了灰层对燃烧气体的扩散阻力,求得的飞灰含碳量仅为0.1%,改进模型求得的飞灰含碳量为3.1%,与测试结果 2.2%更为接近;自带模型和改进模型求得的炉膛出口O2体积百分比分别为3.0%和3.3%,误差在±10%范围内。     

分层燃烧装置常见故障解析

分层燃烧技术的开发，对正转链条锅炉燃烧状况的改善，对提高锅炉出力和热效率，降低炉渣含碳量节约能源，对减少排放控制环境污染，无疑都起到了积极的作用，可分展给煤装置在运行中暴露出来的问题及一些常见的故障，也让许多用户感到无奈和烦恼，本文将常见的一些故障及解决方法做一介绍。１由湿煤和冻煤引起的断煤故障 众所周知，原形式的锅炉煤斗仅是一个承接和传输燃煤的载体，燃煤从上部下煤管输往炉排，基本上呈直线状，沿程传输阻力较小，即便如此，在煤斗前箱体的内侧，还经常发生粘积煤现象，时间久了造成棚煤。而分层燃烧的煤斗…     

煤层自动翻松装置

1 问题的提出　　传统的履带式链条锅炉,通常是通过链条(炉排)的连续转动,不断将煤斗中的燃煤经煤闸门徐徐拖出,带入炉膛。一定厚度的煤层经加热干燥、干馏析出挥发物,形成焦炭燃烧。在燃烬形成灰渣后,翻入渣坑。由于燃煤从煤斗落下,压得实、易板结,进入炉膛后,即使司炉工勤拨火,煤层依旧难烧透,造成煤耗高,同时传统的操作方式存在三个不足:　　a.不安全,火苗和煤粒在拨火时会窜起,烫伤司炉工;　　b.只能间断或短时间内达到升温效果,使锅炉供汽压力不稳定;　　c.劳动强度大,操作环境恶劣,污染严重。　　鉴于这种现状,有必要寻求一种方法改善…     

分层给煤装置的常见故障及解决方法

分层燃烧技术的应用 ,对改善正转链条锅炉的燃烧状况 ,提高锅炉出力和热效率 ,降低炉渣含碳量节约能源 ,减少排放控制环境污染 ,无疑都起到了积极的作用 ,但分层给煤装置在运行中暴露出来的问题及一些常见的故障 ,也让许多用户感到无奈和烦恼 ,这里将常见的一些故障及解决方法做一介绍。1由湿煤和冻煤引起的断煤故障众所周知 ,原形式的锅炉煤斗 ,仅是一个承接和传输燃煤的装置 ,燃煤从上部下煤筒传输到炉排 ,基本上呈直线形 ,沿程阻力较小 ,即便如此 ,在煤斗前部倾斜箱体的内侧 ,还经常发生粘积煤的现象 ,时间久了造成棚煤。而分层给煤装置…     

燃煤链条炉排锅炉三维数值建模及燃烧过程分析

燃煤链条炉排锅炉燃烧过程十分复杂,为了对燃煤链条炉排锅炉煤层燃烧特性和机理进行深入分析,应用三维层燃模型对链条炉排锅炉燃烧过程进行了模拟计算,并与实验结果进行比较。对比发现模拟计算值与实验符合较好,说明模型能准确反映床层的燃烧特性。同时对不同配风方式下链条炉排锅炉燃烧过程进行了分析对比,发现炉拱结合推迟配风对原煤引燃有促进作用。     

Ash-forming elements in four Scandinavian wood species. Part 1: Summer harvest

Woody biomass in Finland and Sweden comprises mainly four wood species: spruce, pine, birch and aspen. To study the ash, which may cause problems for the combustion device, one tree of each species were cut down and prepared for comparisons with fuel samples. Well-defined samples of wood, bark and foliage were analyzed on 11 ash-forming elements: Si, Al, Fe, Ca, Mg, Mn, Na, K, P, S and Cl. The ash content in the wood tissues (0.2–0.7%) was low compared to the ash content in the bark tissues (1.9–6.4%) and the foliage (2.4–7.7%). The woods’ content of ash-forming elements was consequently low; the highest contents were of Ca (410–1340 ppm) and K (200–1310), followed by Mg (70–290), Mn (15–240) and P (0–350). Present in the wood was also Si (50–190), S (50–200) and Cl (30–110). The bark tissues showed much higher element contents; Ca (4800–19,100 ppm) and K (1600–6400) were the dominating elements, followed by Mg (210–2400), P (210–1200), Mn (110–1100) and S (310–750), but the Cl contents (40–330) were only moderately higher in the bark than in the wood. The young foliage (shoots and deciduous leaves) had the highest K (7100–25,000 ppm), P (1600–5300) and S (1100–2600) contents of all tissues, while the shoots of spruce had the highest Cl contents (820–1360) and its needles the highest Si content (5000–11,300). This paper presented a new approach in fuel characterization: the method excludes the presence of impurities, and focus on different categories of plant tissues. This made it possible to discuss the contents of ash element in a wide spectrum of fuel-types, which are of large importance for the energy production in Finland and Sweden.     

NEXT GENERATION ENGINEERED MATERIALS FOR ULTRA SUPERCRITICAL STEAM TURBINES

正1 ABSTRACT To reduce the effect of global warming on our climate,the levels of CO2emissions should be reduced.One way to do this is to increase the efficiency of electricity production from fossil fuels.This will in turn reduce the amount of CO2emissions for a given power output.Using US practice for efficiency calculations,then a move from a typical US plant running at 37%efficiency to a 760℃/38.5 MPa(1 400/5 580 psi)plant running at 48%efficiency would reduce CO2emissions by 170kg/MW.hr or 25%.     

Contents in Volume 23,2014

<正>~~     

Aerodynamic performance effects of leading-edge geometry in gas-turbine blades

The purpose of this paper is to illustrate the advantages of the direct surface-curvature distribution blade-design method, originally proposed by Korakianitis, for the leading-edge design of turbine blades, and by extension for other types of airfoil shapes. The leading edge shape is critical in the blade design process, and it is quite difficult to completely control with inverse, semi-inverse or other direct-design methods. The blade-design method is briefly reviewed, and then the effort is concentrated on smoothly blending the leading edge shape (circle or ellipse, etc.) with the main part of the blade surface, in a manner that avoids leading-edge flow-disturbance and flow-separation regions. Specifically in the leading edge region we return to the second-order (parabolic) construction line coupled with a revised smoothing equation between the leading-edge shape and the main part of the blade. The Hodson–Dominy blade has been used as an example to show the ability of this blade-design method to remove leading-edge separation bubbles in gas turbine blades and other airfoil shapes that have very sharp changes in curvature near the leading edge. An additional gas turbine blade example has been used to illustrate the ability of this method to design leading edge shapes that avoid leading-edge separation bubbles at off-design conditions. This gas turbine blade example has inlet flow angle 0°, outlet flow angle −64.3°, and tangential lift coefficient 1.045, in a region of parameters where the leading edge shape is critical for the overall blade performance. Computed results at incidences of −10°,   −5°,   +5°,   +10° are used to illustrate the complete removal of leading edge flow-disturbance regions, thus minimizing the possibility of leading-edge separation bubbles, while concurrently minimizing the stagnation pressure drop from inlet to outlet. These results using two difficult example cases of leading edge geometries illustrate the superiority and utility of this blade-design method when compared with other direct or inverse blade-design methods.     

Hydrogen production by steam-gasification of carbonaceous materials using concentrated solar energy – V. Reactor modeling,optimization, and scale-up

A chemical reactor for the steam-gasification of carbonaceous particles (e.g. coal, coke) is considered for using concentrated solar radiation as the energy source of high-temperature process heat. A two-phase reactor model that couples radiative, convective, and conductive heat transfer to the chemical kinetics is applied to optimize the reactor geometrical configuration and operational parameters (feedstock's initial particle size, feeding rates, and solar power input) for maximum reaction extent and solar-to-chemical energy conversion efficiency of a 5 kW prototype reactor and its scale-up to 300 kW. For the 300 kW reactor, complete reaction extent is predicted for an initial feedstock particle size up to 35 μm at residence times of less than 10 s and peak temperatures of 1818 K, yielding high-quality syngas with a calorific content that has been solar-upgraded by 19% over that of the petcoke gasified.     

Assessment methods of material ageing using Sdobyrev''s creep rupture model

The physical aspects of the activation energy, in higher and high temperatures, of the metal creep process were examined. The research results of creep-rupture in a uniaxial stress state and the criterion of creep-rupture in biaxial stress states, at two temperatures, are then presented. For these studies creep-rupture, taking case iron as an example the energy and pseudoenergy activation was determined. For complex stress states the criterion of creep-rupture was taken to be Sdobyrev's, i.e. σ_red = σ₁ β + (1 − β)σ_i, where: σ₁-maximal principal stress, σ_i-stress intensity, β-material constant (at variable temperature β = β(T)). The methods of assessment of the material ageing grade are given in percentages of ageing of new material in the following mechanical properties: 1) creep strength in uniaxial stress state, 2) activation energy in uniaxial stress state, 3) criterion creep strength in complex stress states, 4) activation pseudoenergy in complex stress states. The methods 1) and 3) are the relatively simplest because they result from experimental investigations only at nominal temperature of the structure work, however, for methods 2) and 4) it is necessary to perform the experimental investigations at least at two temperatures.     

Production of hydrogen from sewage biosolids in a continuously fed bioreactor: Effect of hydraulic retention time and sparging

Hydrogen was produced from primary sewage biosolids via mesophilic anaerobic fermentation in a continuously fed bioreactor. Prior to fermentation the sewage biosolids were heated to 70 °C for 1 h to inactivate methanogens and during fermentation a cellulose degrading enzyme was added to improve substrate availability. Hydraulic retention times (HRT) of 18, 24, 36 and 48 h were evaluated for the duration of hydrogen production. Without sparging a hydraulic retention time of 24 h resulted in the longest period of hydrogen production (3 days), during which a hydrogen yield of 21.9 L H₂ kg⁻¹ VS added to the bioreactor was achieved. Methods of preventing the decline of hydrogen production during continuous fermentation were evaluated. Of the techniques evaluated using nitrogen gas to sparge the bioreactor contents proved to be more effective than flushing just the headspace of the bioreactor. Sparging at 0.06 L L min⁻¹ successfully prevented a decline in hydrogen production and resulted in a yield of 27.0  L H₂ kg⁻¹ VS added, over a period of greater than 12 days or 12 HRT. The use of sparging also delayed the build up of acetic acid in the bioreactor, suggesting that it serves to inhibit homoacetogenesis and thus maintain hydrogen production.     

汽轮机数字电液调节系统挂闸异常的技术完善

分析了200MW汽轮机数字电液调节系统在运行中存在的挂闸异常问题,采取了相应的技术处理措施,且运行实践效果良好。     

新型高压共轨ECU升压模块的数字化开发与优化

为了提高喷油器电磁阀的响应速率,提出了一种基于CPLD(复杂可编程逻辑器件)应用于高压共轨ECU的数字升压模块。鉴于该升压电路结构参数多,其升压电压的恢复响应要求高等特征,基于Pspice建立了升压电路的仿真模型,研究了不同电路参数下升压模块的输出特性,全面优化了该升压模块的性能。结果显示,该升压模块的最大转换效率可以达90%以上。在柴油发动机上对ECU的试验表明,升压电压最大波动不超过10%,其恢复时间仅为1.3ms,功率管最大温升仅为41℃,满足整机运行范围内ECU的需求。     

Trace metal chemistry and silicification of microorganisms in geothermal sinter, Taupo Volcanic Zone, New Zealand

As part of a pilot study investigating the role of microorganisms in the immobilisation of As, Sb, B, Tl and Hg, the inorganic geochemistry of seven different active sinter deposits and their contact fluids were characterised. A comprehensive series of sequential extractions for a suite of trace elements was carried out on siliceous sinter and a mixed silica-carbonate sinter. The extractions showed whether metals were loosely exchangeable or bound to carbonate, oxide, organic or crystalline fractions. Hyperthermophilic microbial communities associated with sinters deposited from high temperature (92–94°C) fluids at a variety of geothermal sources were investigated using SEM. The rapidity and style of silicification of the hyperthermophiles can be correlated with the dissolved silica content of the fluid. Although high concentrations of Hg and Tl were found associated with the organic fraction of the sinters, there was no evidence to suggest that any of the heavy metals were associated preferentially with the hyperthermophiles at the high temperature (92–94°C) ends of the terrestrial thermal spring ecosystems studied.