转炉石灰石双渣低成本工艺研究与实践

通过对转炉炼钢前期脱磷和石灰石造渣的理论分析,开发了一种降低成本的转炉炼钢工艺。在脱磷期用石灰石代替石灰作为造渣剂,脱磷结束后,倒除部分富磷渣,然后进行小渣量脱碳,吹炼终点保留脱碳渣用于下一炉脱磷。研究结果表明：与常规冶炼工艺相比,采用石灰石双渣工艺,转炉的石灰石消耗45 kg/t,轻烧白云石消耗20 kg/t,渣料成本10.5元/t,同比石灰双渣法吨钢成本降低9.6元。吹炼终点钢水w（P）控制在0.008%～0.018%,平均为0.011%,满足冶炼工艺的要求。     

60t Consteel电弧炉不供电炼钢工艺技术开发

开发了60 t Consteel电弧炉适合于兑铁水不供电炼钢工艺的炉壁集束氧枪等工装设备技术,同时开展60 t Consteel电弧炉兑铁水不供电炼钢工艺的试验研究工作。研究了电弧炉在兑铁水状态下的冶炼工艺,包括冶炼过程装料制度、冶炼过程供氧、造渣制度等,从而开发成功60 t Consteel电弧炉不供电炼钢工艺,取得良好的经济效益的同时,提高了产品质量。     

电弧炉石灰石造渣快速冶炼碳素结构钢工艺

介绍某厂在不吹氧的条件下，电弧炉用石灰石造渣和包内合金化沉淀脱氧的快速冶炼碳素结构钢的新工艺。该工艺冶炼的钢的力学性能和冷弯试验全部符合ＧＢ７００－８８《碳素结构钢》的标准。该工艺的平均每炉冶炼时间比原工艺缩短２６ｍｉｎ；电耗比原工艺降低９８ｋＷ·ｈ／ｔ。     

LF炉热态渣回收再利用的实践

介绍了某钢厂在进行热态LF炉渣回收再利用的实践及经验.通过理论计算结合现场试验结果研究了LF炉热态渣回收再利用对冶炼的影响.研究表明,LF炉热态渣在LF炉造渣时循环使用,可快速形成低熔点渣系,改善渣的流动性.在满足造渣和脱硫效果基础上,LF炉热态渣回收再利用工艺,每炉减少石灰消耗500 kg,减少铝球24 kg,平均炉...     

石灰石抑制石油焦和煤混烧过程NO排放机理的研究

循环流化床(CFB)锅炉进行石油焦和煤混烧,是高效、清洁利用高硫石油焦的有效途径。混烧过程中,为满足SO₂排放要求,通常采用炉内添加石灰石的脱硫工艺,而该工艺会引起炉内氮氧化物浓度的变化。基于工业CFB锅炉投停石灰石NO_x“突降缓升”的实验现象,在实验室规模的20 kW CFB锅炉和立式管式炉中,结合机理实验、物相分析和Factsage计算的方法,明确了石灰石抑制NO排放的机理。结果表明：CFB内强烈的氧化还原交变气氛下,固硫中间产物CaS是抑制NO排放的关键物质;CaS不仅能够促进CO还原NO,而且自身参与了分解NO的化学反应而被消耗,且反应在低温下更容易进行。研究结论可为深挖CFB低氮燃烧潜力,实现炉内NO和SO₂的一体化脱除提供有价值的指导方案。     

直流磁镜式钢包精炼炉的设想

直流磁镜式炼钢电弧炉在我厂投产已五年了,此五年炼钢的实践证明,直流磁镜式炼钢电弧炉在还原期和出钢升温期较交流炼钢电弧炉要好的多,从总的工艺过程讲,直流磁镜式炼钢电弧炉较交流炼钢电弧炉要好,平均吨钢水电耗下降百度左右。目前,我国使用的钢包精炼炉都是交流钢包炉,而钢包精炼炉的工艺主要是还原期和出钢升     

平面四杆机构在电弧炉炉盖旋转机构中的应用

将平面四杆机构引入到炼钢电弧炉炉盖旋转机构的设计当中,四杆机构不仅能够满足电弧炉的工作要求,而且有效缩短了电弧炉的短网长度,从而降低短网上无功功率的损耗,提高电弧炉的工作效率,降低吨钢电耗。     

碳化硅材料用于炼钢

我厂最近在3t电弧炉上,冶炼ZG25铸钢件过程中,应用SiC材料代替传统的C、Si粉还原,进行了13炉次的试验,取得了较好的效果。感到在一般碳素钢的冶炼中,用SiC材料代替传统的C、Si粉进行炼钢还原,不但能缩短还原时间,降低冶炼成本,节电,铸件质量完全能达到标准要求,且具有操作简单,一般工人都能较快熟练掌握工艺要点等优点。     

炼钢电弧炉管式水冷系统的设计与应用

对炼钢电弧炉炉壁，炉盖所采用的结构形式进行了归纳分类。对管式水冷系统的优点，设计要点作了详细的叙述，并简单介绍了新型喷淋式水冷炉盖。     

电弧炉取消还原期冶炼碳素钢工艺探讨

本文介绍了电弧炉炼钢中取消还原期冶炼碳素钢工艺的试验结果及其与传统工艺各项参数的比较。试验证明,用该工艺冶炼碳素钢,每炉冶炼时间缩短32分钟,每吨钢液降低电耗40千瓦·时,且操作可行,质量可靠。是提高经济效益的一项行之有效的炼钢工艺。     

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.     

Contents in Volume 23,2014

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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.