层燃炉中的推迟配风法及空气二次利用原理

推迟配风法是作者提出的一种新型的层燃炉配风法，它能达到最大限度的空气二次利用，从而降低锅炉的过量空气系数。其燃烧学“烧中间、促两头”的特点，能有效地降低炉渣含碳量，另外，它还能相当大量地减小飞灰的带出量。     

新技术新产品推广

新技术新产品推广蒸汽喷射锅炉消烟助燃器蒸汽喷射锅炉消烟助燃器（简称助燃器）是在蒸汽二次风的基础上发展起来的新型节能技术产品，其作用远远超过蒸汽二次风，是节煤、节汽、助燃，提高锅炉热效率，消烟除尘的有效途径。经北京某厂在一台“ＳＨＬ—１０—１３”型（８...     

层燃炉中煤的燃烧预热区和燃烬区调风装置的设计

本文分析了层燃炉中普遍使用的风道调风挡板在煤的燃烧预热和燃烬两区中调风和密封性能不良的情况,提出了一种新型的风室内纵向二次调风装置。此装置能使煤的预热和燃烬两区的配风优化,达到节能,提高燃烧效率之目的。     

用活动遮热板装置改善层燃炉的煤种负荷适应性

分析了国内现有燃煤层燃炉燃烧过程中存在的主要问题，在此基础上，提出了用活动遮热板装置来改善层燃炉的煤种，负荷适应性的思想；简单介绍了活动遮热板的物理模型。工作原理及其主要结构组成；用试验与传热计算的方法论证了活动遮热板用于层燃炉中的可行性及其对层燃炉内温度场，燃烧效率的影响，试验与传热计算表明。活动遮热板应用于层燃炉是完全可行的，并且可大大改善其煤种和负荷的适应性。     

层燃炉低NOX再燃烧技术的实验研究

在分析煤燃烧过程中NOx生成及破坏机理的基础上，提出采用再燃烧技术降低层燃炉NOx排放的方法，并通过热态单元体模拟炉，在不同高度上布置再燃燃料喷嘴和燃尽风喷嘴，实验研究了再燃燃料量、再燃区停留时间和主燃区空气过剩系数等因素对层燃炉NOx排放的影响。结果表明：采用再燃烧技术能有效降低NOx的排放，在实验条件下，降低NOx排放的最大值约为60％。图3表1参3     

空气二次风和蒸汽二次风消烟除尘效果的比较

一、概述热电厂一般地处供热中心,环境保护要求高,烟气排放有严格规定,故各单位对消烟尘都很重视。目前小型热电厂除选用效率较高除尘器外,最广泛的是采用二次风强化燃烧来达到消烟除尘目的。利用空气二次风和蒸汽二次风同样可以达到较满意消烟除尘的效果。但有些厂因喷嘴角度安装位置不正确,风速风量不够而引起空气二次风除尘效果不佳。从理论上讲无论是采用空气二次风还是蒸汽二次风其效果好坏,主要看二次风与炉排     

不同配风方式下层燃炉煤层NO_x析出特性研究

层燃炉中大颗粒煤燃烧特性与煤粉燃烧特性差别很大,为了准确掌握层燃炉煤中氮元素的析出规律,在层燃单元体炉上进行了不同配风方式下煤层表面NOx析出特性的对比实验。实验中测试了不同煤种煤层表面NOx浓度和O2、CO2、CO、H2浓度,并将不同配风方式下数据进行了对比分析,得到了层燃炉煤层表面NOx浓度沿炉排呈现双峰分布的特点,在煤层引燃5 min左右NOx形成第一个峰值,内蒙煤最大峰值为769 mg/m3,淮南煤最大峰值为695 mg/m3;同时得到了不同配风方式下煤层表面NOx析出双峰的变化规律,为实际工业锅炉低NOx燃烧运行提供理论依据。     

层燃炉风室单侧均匀进风的流体动力模型

一、前言 层燃炉风室配风均匀性的重要性已为人们所认识。近几年来,很多研究者,锅锅厂家对横向配风均匀性问题做了不少的理论和实验研究工作。然而,对风室内的流体动力过程和配风特性的认识主要是经验性的,能较好地解释实验现象,为大家所接受的理论模式还比较缺乏。本文应用流体力学的基本原理,建立了层燃炉中最基本的配风情况——单侧均匀进风问题的流体动力模型,并根据这一模型,分析了几何结构、阻力特性对风室配风均匀性的影响。     

单侧进风层燃炉的横向均匀配风的试验研究

改善单侧进风层燃炉的横向配风均匀性可以提高锅炉运行效率。利用测压探针和示踪粒子,实测了空风室、流线型隔板、上直隔板、下直隔板等四种风室模型结构多个工况下的配风均匀性。对风室进口处隔板的具体结构进行了分析讨论和多次试验改进,提出了一种可以兼顾气流平衡和均流的结构。通过对比发现,下直隔板风室是一种比较理想的风室结构,给出了结构尺寸的建议,可用于层燃炉风室的设计和节能改造。     

通过不同配风方式研究层燃炉非阻力型正压的机理

为揭示层燃炉非阻力型正压的机理,建立了实验台,利用天然气模拟层燃炉内挥发分的燃烧.采用动态压力传感器测量了炉内的压力波动.研究了2种不同配风方式在不同流量下的压力波动幅值,结合数值模拟对这2种配风方式下炉内气相燃烧特征进行了比较分析.结果表明:配风对非阻力型正压有显著影响,这种现象可用"涡脱落诱导微爆燃"的非阻力型正压解释.     

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.