介绍国外电站锅炉未燃碳的几种测定法

测定燃煤锅炉的未燃碳含量是降低煤耗的重要措施。本文介绍几种国外在运行中测定未燃碳的方法,并重点介绍火焰图象处理技术法。后者在日本仙台发电厂进行了成功试验。     

飞灰未燃尽碳对吸附烟气汞影响的试验研究

采用HYDRA AA全自动测汞仪对3个燃煤电厂的飞灰未燃尽碳进行测试,并利用垂直炉试验系统对电厂飞灰吸附烟气汞进行了试验研究.结果表明：不同燃煤电厂飞灰中的未燃尽碳含量不同是由于各电厂不同煤种、不同燃烧工况以及机组的不同参数造成的;同一电厂的飞灰在灼烧后与原灰相比,对烟气汞的吸附效率相差不大;除了飞灰中的未燃尽碳对汞有吸附外,尾矿对汞也有一定的吸附作用;未燃尽碳含量高的飞灰对汞的吸附效率也较高.     

影响循环流化床锅炉飞灰中碳未燃尽损失因素的探讨

对循环流化床锅炉中煤的燃烧过程简要地进行了分析,对导致飞灰含碳量偏高的因素进行了总结,并,从设计、运行方面对降低飞灰含碳量给出了建议。     

燃煤电厂飞灰碳含量与PAHs有机污染物吸附量之间相关性研究

以五家燃煤电厂为例,实验分析了飞灰总碳、元素碳、有机碳含量,并与飞灰中多环烃类（PAHs）有机污染物吸附量作了相关分析;此外研究了燃煤排放PAHs与炉前煤中PAHs的关联性,从煤化学、煤燃烧学角度探讨了PAHs的吸附反应机制,提出煤粉燃烧过程中PAHs的一种重要形成机制-未燃碳颗粒及吸附反应机制,指出飞灰中的碳位不仅是PAHs的重要吸附位,同时也是PAHs的重要反应位。     

转炉烟气未燃排出的自动化

<正> 转炉烟气的未燃排出是一种排出转炉烟气的现代方法,这种方法可以保证节省能源和保护环境,而且可以回收转炉炉气供随后使用。在卡拉干达冶金联合企业掌握了转炉烟气未燃排出的方法以后,所有新投产的大转炉都在水套处配备了烟气未燃排出设备。就目前来讲,解决与烟气排出的各项操作以及炉气回收的自动化有关的问题,具有重要的意义。     

65t/h抛煤机锅炉飞灰回燃装置改造的实践

针对抛煤机链条炉飞灰可燃物含量的问题，将平板式分离器改为槽形分离器，同时在炉膛敷设回燃带，提高燃烧温度。运行结果表明：锅炉平均出力提高5～10t/h，产汽标煤耗下降8％。     

循环流化床锅炉中飞灰颗粒孔隙结构的实验研究

实验研究借助氮吸附仪和扫描电子显微镜全面分析了循环流化床锅炉中飞灰颗粒的孔隙结构、吸附/脱附等温线、迟滞回线和孔分布等方面的特点和特性。飞灰的筛分实验和含碳量测定中,得到了循环流化床锅炉飞灰的含碳量在粒径45～25μm之间出现峰值。氮吸附实验结果表明,不同粒径段飞灰的吸附等温线近似为第Ⅱ类;飞灰的孔分布很宽,最可几孔径在4 nm左右,其中中孔所占比例最大,基本均达到60%以上,但未发现微孔的存在;中孔和大孔孔型主要为锥形孔、平行板狭缝孔和墨水瓶状孔。     

循环流化床锅炉飞灰中碳的形成机理

通过对循环流化床(CFB)锅炉飞灰含碳量分布及飞灰残碳形态的测量、CFB燃烧温度下焦炭失活过程的试验研究以及流化床条件下煤颗粒燃烧过程的分析.探讨了循环流化床锅炉飞灰中碳的形成机理.结果表明:实际运行的CFB锅炉飞灰中含碳量具有明显的不均匀性,残碳集中于25～50 μm的飞灰颗粒内;真实密度和XRD测量均表明,焦炭失活的2个条件是温度和时间,温度高于800℃,焦炭失活开始发生,并且随着时间的增加,失活程度提高;焦炭颗粒长时间停留在主循环回路中,反应活性下降,由于颗粒的碎裂和磨耗,形成了飞灰中粒径较小的残碳;煤中的细小煤粒首次通过炉膛时未燃尽且未被分离器收集,形成了飞友中较大颗粒的残碳.     

高效陶瓷多管除尘器附飞灰回燃

在水膜除尘器前加装陶瓷多管除尘器,形成两级除尘,除下的灰由二次风引射进入炉膛后部循环燃烧,不但降低了排烟浓度,还可提高锅炉7％的热效率。     

发动机燃烧室狭缝间隙处未燃碳氢生成的研究

在利用激光干涉法测量定容燃烧弹燃烧室狭缝间隙内未燃混合气热力状态参数的基础上，分析了不同狭缝间隙宽度下狭缝内未燃混合气双壁激冷厚度的变化规律，定量地计算了狭缝容积内未燃碳氢的生成量，这表明，狭缝间隙处未燃混合气的双壁激冷厚度不仅与狭缝宽度有关，也与未燃混合气在狭缝内所处未燃混合气的双壁激冷厚度不仅与狭缝宽度有关，也与未燃混合气在狭缝内所处的位置有关。     

生物质及其半焦混燃特性热重实验研究

采用热重分析方法研究了木质含量分别为0,20%,50%,80%和100%的生物质及其半焦的掺混物在空气气氛下的燃烧特性,并对失重数据进行了动力学分析。结果表明:随着木质含量的增大,DTG曲线向低温区移动,燃料的起始反应温度、剧烈反应温度、终止反应温度降低,最大失重速率、平均反应性增大;掺混物在相同反应时间内的实际转化率大于计算转化率,表明混合物组分间存在相互促进的协同作用,并且掺混物中木质含量越高,促进作用越明显;木质含量为0和20%的掺混物失重过程可由一个动力学方程进行合理的拟合,其余3个掺混物则需分段拟合。     

浅析内燃机车振动

针对资阳内燃机车厂机车振动情况,分析各种振动原因,找出不同的解决办法.通过改进设计、改进工艺、加强质量控制和管理,基本上解决了机车振动问题.     

A preliminary solar-hydrogen system for Jordan: Impacts assessment and scenarios analysis

Energy sector in Jordan faces serious challenges today. Jordan as a non-oil country depends by 96% on imported fuel to cover its demands. The present work seeks to improve an alternative fuel that can support the goals of National Energy Strategy in Jordan. Therefore; a mathematical model was developed to investigate the possibility of producing solar-hydrogen fuel in Jordan. Ma'an city was chosen to be the location of solar-hydrogen plant. The high solar insulation and the availability to supply the plant with water from Aqaba Gulf directly and/or from Red-Sea Dead-Sea Cannel make Ma'an the suitable location for the plant. A system with photovoltaic (PV) cell array and proton electron membrane (PEM) electrolyzer was suggested to be the connection system for the plant. Accordingly, two different scenarios were proposed for hydrogen production with different hydrogen production doubling time, the first scenario is ${\mathit{\theta }}_{\mathit{h}1}=2+0.15\left(\mathit{n}?1\right)$ year, while the second scenario is ${\mathit{\theta }}_{\mathit{h}2}=4+0.15(\mathit{n}?1)$ year. Eight different economic, social, and environmental parameters, which directly affect solar-hydrogen production, were evaluated and investigated for Jordan up to year 2060. Accordingly, the research study concluded that solar-hydrogen fuel can potentially offer a good option as an alternative fuel for Jordan. Starting the production at year of 2020 can provide a good sharing in energy demand sector by the end of the year 2060.     

Effects of physical properties on one-dimensional downward smoldering of char: Numerical analysis

Smoldering combustion in a packed bed of carbonaceous material is a very complex process, where numerous physical and chemical parameters are involved. This study was conducted to examine the impact of several physical parameters on the behavior of natural downward smoldering. For that purpose, a one-dimensional homogeneous model has been developed. Due to the fact that drying, pyrolysis or oxidative degradation occurs significantly faster than carbon oxidation, only the latter phenomenon was taken into account. The model was evaluated by comparison of numerical simulation results with experimental observations. Sensitivity analysis calculations of different physical properties of the bed material with respect to smoldering time, smoldering front velocity and front temperature suggest that in future experiments special attention should be devoted to accurate determination of bed shrinkage, bulk carbon density, mean void size, oxygen diffusivity in fuel bed.     

大颗粒碳／炭着火规律的研究

本文研究了大颗粒碳／炭的着火过程，通过实验和数值模拟发现，大颗粒碳／炭的着火与小颗粒的不同，它的温升历程不存在突跃现象，因此也就不存在ｄ＾２Ｔ／ｄｔ＾２＝０的着火特征点。为此，本文针对大颗粒碳／炭着火过程的特点，提出了一个新的着火判据，据此建立了大颗粒碳／炭着火模型，导出了与小颗粒碳／炭相同形式的着火表达式。实验验证了在小颗粒模型下推导出的着火温度与煤质之间的通用关系仍适用于大颗粒碳／炭的着火。     

Waste pyrolysis and generation of storable char

Sustainable cities require the generation of energy from waste that cannot be economically reused or recycled. This study focuses on slow pyrolysis that can generate a high yield of char along with liquid and gas products from waste. Char is high in energy content, storable and transportable with low cost so that it can be used as an intermediate medium for high efficiency energy conversion. Pre‐processed municipal waste pellets, wood and grass were pyrolysed in a batch type reactor for a final temperature ranging from 350 to 700°C, and the char products were characterized. The mass yields of char ranged from 55 to 20% for the tested temperature range, recovering 70–30% of energy and 62–30% of carbon in the raw material. The gross calorific value of char was 30–35 MJ kg^?1 on a dry ash free basis. The ash content of raw materials was a key parameter for the quality of char, since its proportion increased by 2–4 times in char depending on the mass yield. A significant amount of volatile metals such as Hg, As and Pb in the waste sample was evaporated at 500°C. Therefore, evaporation of volatile metals was another important parameter in determining the pyrolysis temperature and fuel residence time. The char did not show significant morphological change in the tested range of temperatures. It was concluded that slow pyrolysis of waste for char production should be performed below 500°C in order to increase the energy yield and also to reduce the evaporation of heavy metals. Copyright © 2006 John Wiley & Sons, Ltd.     

灰煤混合燃料的燃烧动力学特性研究

利用TGA/SDTA851e型热重分析仪,对煤及不同灰煤比的混合燃料进行了热失重实验,获得了其热失重特性曲线。采用单个扫描速率的Coats-Redfern法、多重扫描速率的FWO（Flynn-Wall-Ozawa）法和Starink法三种典型的热分析方法求取了各样品的动力学参数。结果表明：随着灰煤比的升高,样品燃烧反应平均过程的活化能增高;灰煤比由0升高到0.15时,样品的活化能、着火温度和燃烬温度变化较大;灰煤比从0.15升高到0.45时,活化能、着火温度和燃烬温度变化较小。同时,通过对比几种分析方法的计算结果,认为采用多重升温速率法求取活化能时要谨慎,建议采用单重升温速率法和多重升温速率法相结合来分析燃料的热解及燃烧机理。     

A downdraft high temperature steam-only solar gasifier of biomass char: A modelling study

A numerical model of a solar downdraft gasifier of biomass char (biochar) with steam based on the systems kinetics is developed. The model calculates the dynamic and steady state profiles, predicting the temperature and concentration profiles of gas and solid phases, based on the mass and heat balances. The Rosseland equation is used to calculate the radiative transfer within the bed. The char reactivity factor (CFR) is taken into account with an exponential variation. The bed heating dynamics as well as the steam velocity effects are tested. The model results are compared with different experimental results from a solar packed bed gasifier, and the temperature profile is compared to an experimental downdraft gasifier. Hydrogen is the principal product followed by carbon monoxide, the carbon dioxide production is small and the methane production is negligible, indicating a high quality syngas production. By applying the temperature gradient theory in the steam-only gasification process for a solar gasifier design, a solar downdraft gasifier improves the energy conversion efficiency by over 20% when compared to a solar packed bed gasifier. The model predictions are in good agreement with the experimental results found in the literature.