循环流化床锅炉燃烧片状无烟煤的飞灰含碳量研究

研究了片状无烟煤的颗粒特性,观察和实测了燃烧该无烟煤的循环流化床锅炉的运行表现,即由于颗粒的片状形貌导致的运行压力和风速的周期性变化以及由此造成的飞灰含碳量的周期性变化。针对片状颗粒特点,利用煤粉锅炉的卫燃带技术调整锅炉热力责任,建立了飞灰含碳量与炉膛出口之间的关系,有效地降低了片状颗粒的飞灰含碳量。     

65t／h抛煤链条炉飞灰回燃装置的研究与实践

本文针对目前６５ｔ／ｈ抛煤链条锅炉飞灰量大，飞灰含碳量高的普遍情况，用气力输送的原理，将从锅炉省煤器下飞灰分离器收集的飞灰以气－固两相流的方式喷入炉膛火焰中心燃烧并形成飞灰循环，达到减少飞灰量及飞灰含碳量的目的，经初步测定，可提高锅炉热效率５％。     

配双进双出磨煤机的W火焰锅炉的燃烧调整试验研究

针对锅炉实际运行中出现的炉膛负压波动大、前墙上部水冷壁超温、飞灰及大渣含碳量高的问题,进行了原因分析,并结合BBD4062双进双出磨煤机的制粉特性,进行了燃烧调整。调整后,锅炉的炉膛负压波动更小,前墙上部水冷壁超温得到缓解,飞灰及大渣含碳量下降。     

600MW燃煤锅炉降低飞灰含碳量的燃烧调整试验研究

针对天津大唐国际盘山发电有限责任公司3号锅炉近期飞灰含碳量偏高的现象,对其进行了燃烧调整试验,主要研究了磨煤机运行方式、燃烧器配风方式、炉膛氧量及煤粉细度的变化对飞灰含碳量的影响,并根据试验结果采取了相应的优化调整措施,使得3号锅炉飞灰含碳量降低到2%以下,取得了良好的效果,提高了机组运行经济性。     

前后墙对冲燃烧锅炉降低飞灰含碳量的燃烧调整试验

分析了浙江浙能长兴发电有限公司3号锅炉飞灰含碳量升高的原因,指出磨煤机研磨能力下降、煤粉过粗、煤粉浓度分配不均匀以及局部缺氧燃烧等是主要原因;介绍了针对巴威DRB-XCL旋流燃烧器的特点,通过采取调整燃烧器调风盘、内、外二次风叶片角度以及提高炉膛氧量等措施,从而降低锅炉飞灰含碳量2%~3%,解决了3号炉飞灰含碳量高的问题,提高了机组运行的经济性。     

简析锅炉飞灰影响因素及控制措施

火力发电厂燃煤锅炉燃烧的调整和优化直接影响到电厂的经济运行,飞灰含碳量是锅炉效率一个重要的调整和控制指标。通过分析燃煤的各种成分,结合机组运行中负荷的变化规律,采取合理的配风方式,对炉膛的燃烧及时进行调整,采取相应的控制方法,达到降低飞灰含碳量的目的,以提高锅炉的效率。     

BP神经网络与改进热力计算结合确定锅炉参数基准值

提出了采用BP神经网络模型与改进热力计算相结合的方法确定锅炉运行参数基准值。计算中采用BP神经网络模型预测飞灰含碳量的基准值,并根据锅炉运行负荷选取炉膛出口烟气温度计算公式,采用登山原理确定过量空气系数的方法确定关键运行参数基准值。最后,以一台HG1025/18.2-M锅炉为例,计算70%、50%负荷下该锅炉运行参数的基准值,得到随着锅炉负荷的降低炉膛出口过量空气系数明显增加,飞灰含碳量和机械未完全燃烧热损失显著降低。证明该方法能够很好地反映锅炉负荷、煤质特性参数改变对运行参数基准值的影响。     

通过冷态模型试验指导改造抛煤机锅炉

通过冷态模型试验指导改造抛煤机锅炉哈尔滨制药厂邓钢，郑懋臣，李强，杨代风抛煤机倒转炉排锅炉，具有上汽快、煤种适应性强等特点。但由于挥发物在炉膛中局部大量析出裂解形成碳黑，以及相当大一部分细煤粒在炉膛内停留时间不够，致使飞灰量及飞灰含碳量大大增加，严重...     

采用统计方法分析燃煤锅炉q_4、炉渣和飞灰含碳量与各运行参数之间的关系

炉渣和飞灰含碳量是构成燃煤工业锅炉主要热损失q_4的主要部分。燃料特性、燃烧方式、锅炉负荷、炉膛温度等参数与q_4、炉渣和飞灰含碳量具有密切的关系。本文采用数理统计的方法对q_4、炉渣含碳量和飞灰含碳量与各运行参数进行了相关性分析,并以相关性变量为基础,采用多元拟合的方法得到了无燃料特性参数条件下的三个拟合公式,且判定了公式在工程上的有效性。     

过量空气系数对W型火焰锅炉燃烧影响的数值模拟研究

过量空气系数是影响W型火焰锅炉燃烧的重要因素.利用数值模拟技术对某电厂300MW"W"型火焰锅炉炉内燃烧进行了4个工况的计算.通过分析各个工况下炉内流场、温度场、NO排放量以及炉膛出口处飞灰含碳量,得出过量空气系数增大时,炉内流场变化不大,炉内温度水平降低,火焰中心上移,NO排放量增大,飞灰含碳量减少.     

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%.     

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.     

Contents in Volume 23,2014

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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。     

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.     

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.