耐火纤维喷涂工艺在加热炉保温施工中的应用

加热炉的炉墙保温效果如何,直接影响加热炉的散热损失大小.通过两种保温工艺的比较,阐述选择优良的保温材料、先进的施工工艺是提高加热炉炉效和降低炉墙表面温度的一个重要手段.     

新型耐火纤维模块锚固结构在台车式加热炉的应用

耐火纤维模块质轻、隔热保温且蓄热损失小被广泛应用于新建或改造升级的高温锻造加热炉中,纤维模块锚固结构稳定性对加热炉使用寿命和运行效果有重要影响。针对高温加热炉炉顶耐火纤维模块易松动和脱落问题,从耐火纤维模块锚固结构、炉内温度和炉内气氛三个方面分析了造成炉顶耐火纤维模块松动和脱落的原因。通过高温模拟实验,得出高温下具有氧化性的炉内气体从耐火纤维模块收缩缝中窜入导致金属锚固件或锚固结构焊接端头被氧化烧损是炉顶耐火纤维模块松动脱落的主要原因。结合现场实际提出了一种新型耐火纤维模块锚固结构,并将其应用于某厂高温台车式加热炉的修理和改造项目,在降低耐火纤维模块安装施工难度、延长耐火纤维炉衬使用寿命、保证加热炉稳定可靠运行、降低生产成本等方面效果明显,取得了显著的经济和社会效益。     

多晶莫来石纤维贴面块在轧钢加热炉的应用

采用多晶莫来石纤维贴面块对加热炉炉内壁保温,减少了炉体的散热损失,降低了炉子燃耗,取得了较好的效果。     

轧钢加热炉节能讲座(五)

<正> 3.3 减少炉膛内的热损失从轧钢加热炉炉膛热平衡可知,炉膛的热损失主要有:炉底水冷管热损失、炉体散热和蓄热损失、炉门及孔隙的辐射和溢气热损失,以及运料机械和工具等的热损失。其中最大热损失是水冷管热损失。▽3.3.1 减少炉底水冷管热损失炉底水冷管是轧钢加热炉的重要构件之一,它承担着炉内料坯的全部重量。这些水冷管不仅带走大量的热量,而且对料坯的受热条件(如对下炉膛的燃烧、传热和水管黑印等)也有     

连续推钢式轧钢加热炉的数值模拟

运用流体动力学计算软件（CFD）FLUENT,对湘潭钢铁公司第二高速线材厂轧钢加热炉的三维流场进行了数值模拟,获得该轧钢加热炉内的气体流动、流速和压力的分布规律.通过与加热炉内的结构特点和实际操作状况对照分析,表明该加热炉的局部结构与操作不相适应,尤其是压力分布不适应加热炉的操作要求,造成炉内供热调节的灵活性降低,从而影响到加热质量.分析结果与加热炉的实际运行状况相符,为加热炉的进一步结构改造提供依据.     

加热炉漏火原因分析与改造

某厂加热炉在改造前存在炉门、炉尾、蓄热箱周围、炉顶两侧、炉底等多处漏火现象,对加热炉的安全运行、产品质量等造成严重影响.分析了该加热炉产生漏火的原因,制定了相应的改造措施.该加热炉改造后,取得了良好效果.     

提高延迟焦化装置加热炉热效率的技改措施

洛阳石化1400kt/a延迟焦化装置加热炉采用一炉两塔流程,于2008年6月投产,计算热负荷为45.41MW,加热炉为两室四管程双面辐射箱式结构,加热介质为减压渣油。为降低装置能耗,于2011年9月对加热炉进行改造。改造内容包括更换燃烧器、改造空气预热器、采用先进控制、改造炉墙和增加仪表监测。改造后,利用FLUENT软件,对燃烧室中燃料气的燃烧特性和新型燃烧器某截面的温度场进行数值模拟,分析得出,新型燃烧器大幅降低了燃烧过程中氮氧化物的生成,保证了燃料气在低过剩空气系数下的充分燃烧;计算表明,空气预热器的改造提高加热炉热效率0.92%。先进控制技术的应用,减轻了劳动强度,提高了调节精度和加热炉运行的平稳率,达到了提高加热炉热效率的目的。综合改造后,加热炉热效率高达93.45%,与改造前相比,热效率提高1.81%。     

节能型的轧钢加热炉

上海第三钢铁厂型钢分厂4＃加热炉自1981年开工至今已有十年，由于年久失修，受热面积小的预热器已损坏，排烟形式为侧下排烟，烟道积水严重，热风温度低，炉墙炉顶散热损失严重，故近几年来能耗一直较高。为此，我们对4＃加热炉进行节能技术改造，将下排烟道改侧上排烟，增加高效管状预热器的换热面积配以高风温，全热风低压JBS烧咀，对炉体进行绝热保温，经过半年多生产实践证明，节能效果明显，吨钢节油10.38公斤／吨，使炉子可比单耗达到冶金部颁布一等奖水平，获得了上海市92年节能技术优秀项目一等奖。一、概况．C钢三厂型钢分厂三…     

钢管再加热炉炉内温度场和流场分布数值模拟

以某公司钢管再加热炉为研究对象,运用Fluent数值仿真软件对钢管再加热炉内温度场和流场进行了数值模拟,获得该加热炉的温度场和流场的分布图。计算结果为优化炉型结构提供了参考依据。     

WZ003040火焰炉顶部供热的热交换计算——《метапдургнческая и горнорудная Промьшпенносгъ》

对采用炉顶烧嘴供热的火焰炉热工进行了数值计算分析。数学模型的假定条件为：忽略火焰的辐射；炉底上放的金属为平板；忽略燃烧产物对金属的传热；炉子砌体为绝热；燃烧产物的比热容与温度无关。该模型与灰体辐射模型相类似。对计算结果进行了分析。指出，炉顶供热可使对金属的给热热流增加8％～13％；绝热炉顶的黑度对金属表面的热流计算结果影响不大，因而计算中可取近似值；气体黑度对炉顶供热的相对作用影响显著；炉顶供热时，炉气温度与炉壁内表面温度相近。     

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

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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.     

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.     

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.