入炉煤水分检测技术与处理模型的研究

介绍了焦炉入炉煤水分检测方案及其工作原理,并给出实际入炉煤水分计算模型。实际应用表明,经该模型处理所得的入炉煤水分结果准确,能够满足工艺要求。煤水分处理模块为焦炉加热优化控制系统提供了可靠数据。     

Aspects of moisture kinetics of coal bottom ash in concrete

The moisture kinetics aspects of composite granular material samples composed of natural sand and bottom ash (BA) from thermoelectric power stations and the use of this material in the production of durable concretes, in relation to water transport, are here discussed. The evaluations of the phenomenon of water absorption by capillarity and the loss of water through air drying until hygroscopic equilibrium, were carried out in accordance with classic procedures found in the literature and also newly developed procedures. The results showed that due to the high porosity of BA, the water absorption by capillarity along with the absorption velocity were higher in the compositions with greater BA content. The values for moisture equilibrium from air drying, absorption from capillarity and sorptivity obtained in the hygroscopic equilibrium tests, carried out on the same samples after absorption, were also higher in the samples with BA. These samples also requited a longer drying time.     

多管回转式煤调湿工艺速度场模拟与试验研究

利用Fluent软件对多管回转式煤调湿工艺进行了速度场模拟,研究了烟气在干燥器内的速度分布,得到了煤调湿过程中烟气的运行规律。在1t/h多管回转式煤调湿装置中进行了半工业化试验,试验结果表明：在吨煤粉烟气耗量2000m3,烟气入口温度245℃,煤粉湿度12%的条件下,煤粉湿度降低到6.7%,达到了炼焦煤调湿效果。     

煤调湿与成型煤工艺运行成本分析

选定STD+I煤调湿工艺与住友成型煤工艺,通过项目投资、工程占地、运行成本、节能效果、增产效益等多方面比较,表明煤调湿工艺更节能,生产运行成本更低。     

气化对煤质的要求

介绍了气流床气化对煤质的要求,论述了煤的水分、反应活性、粒度和灰分对气化的影响。研究表明,煤的内水含量是决定煤浆性能的主要因素,灰渣的黏温曲线比灰熔点对气化炉的操作更具指导意义,选择在操作温度区间灰渣黏度变化平缓的煤种有利于气化炉的安全、平稳运行。     

煤调湿应用于煤处理工艺的探讨

介绍了煤调湿技术的发展过程,对比三代煤调湿技术的差异,讨论了增设煤调湿装置对煤处理工艺流程带来的变化,为设计选用提供了参考。对导热油煤调湿、蒸汽煤调湿和气力分级煤调湿的4种实施方案进行了分析比较,提出了工程应用中需注意的问题。     

煤调湿工艺数学模型与计算

以煤调湿反应器为控制体,建立了水分物料平衡和控制体热量平衡数学模型.在理论分析的基础上,计算得到烟道废气量、入口废气温度、出口废气温度、入口煤粉湿度对调湿后煤粉湿度和废气湿含量的影响,计算结果可以作为煤调湿工艺设计和优化的理论依据与参考.     

宝钢煤调湿技术的改进

对煤调湿技术在宝钢的完善从工艺和设备方面进行了介绍,对改进后的煤调湿投运后出现的新问题及对策进行了论述,采取对策后,煤调湿的运转率提高,干燥机非正常停机次数减少,实现了蒸汽凝液的全量回收,杜绝了布袋结露积灰现象。     

Influence of dextrin content and sintering temperature on the properties of coal fly ash-based tubular ceramic membrane for flue gas moisture recovery

In this paper, in order to reduce the preparation cost of high-performance ceramic membrane, coal fly ash-based tubular ceramic membrane for flue gas moisture recovery was prepared, and its properties were optimized from two aspects: pore-forming agent (dextrin) content and sintering temperature. The results show that the ceramic membrane with dextrin content of 3 wt.% and sintering temperature of 1150 ℃ has the best performance. Through characterization, the ceramic membrane exhibits an open porosity of 42.0 %, mechanical strength of 26.6 MPa, average pore size of 0.49 μm, pure water flux of 5616 L/(m² barh). And, it has excellent corrosion resistance in acid and alkali. In addition, the flue gas moisture recovery performance of coal fly ash-based tubular ceramic membrane was studied experimentally. The highest water recovery ratio and the highest recovered water flux is 87.7 % and 6.01 kg/(m² h, respectively.     

入炉煤水分对炼焦过程及焦炭质量的影响

通过测定入炉煤水分分别为1%、6%和12%时煤料堆密度、升温速度及坩埚焦性质,得出入炉煤水分对其性质的影响。降低入炉煤水分虽然对煤料本身性质影响不大,但是其在炭化室内结焦过程的动态发生了显著变化,可显著提高焦炉生产能力及改善焦炭质量。入炉煤水分为1%时,煤料堆密度、升温速度及坩埚焦的性质都大大好于入炉煤水分为6%和12%这两种情况。     

CFD modeling of MPS coal mill with moisture evaporation

Coal pulverizers play an important role in the functioning and performance of a PC-fired boiler. The main functions of a pulverizer are crushing, drying and separating the fine coal particles toward combustion in the furnace. It is a common experience that mill outlet pipes have unequal coal flow in each pipe and contain some coarse particles. Unequal coal flow translates into unequal air-to-fuel ratio in the burner, deviating from the design value and thus increasing unburned carbon in fly ash, NO_x and CO. Coarser particles at the mill outlet originate from poor separation and decrease the unit efficiency. In addition, coarser particles reduce burner stability at low load. Air flow distribution at the mill throat, as well as inside the mill, significantly influences the mill performance in terms of separation, drying, coal/air flow uniformity at the mill outlet, wear patterns and mill safety. In the present work, a three-dimensional computational fluid dynamics (CFD) model of the MPS Roll Wheel pulverizer at Alliant Energy's Edgewater Unit 5 has been developed. The Eulerian-Lagrangian simulation approach in conjunction with the coal drying model in Fluent, a commercial CFD software package, has been used to conduct the simulation. Coal drying not only changes the primary air temperature but it also increases the primary air flow rate due to mass transfer from coal. Results of the simulation showed that a non-uniform airflow distribution near the throat contributes significantly to non-uniform air-coal flow at the outlet. It was shown that uniform velocity at the throat improves the air and coal flow distribution at the outlet pipes. A newly developed coal mill model provides a valuable tool that can be used to improve the pulverizer design and optimize unit operation. For example, reject coal rate, which is controlled by the air flow near the mill throat, can be reduced. The model can also be used to further aid in identifying and reducing high temperature or coal-rich areas where mill fires are most likely to start.     

The effect of moisture content and air-drying on spontaneous combustion characteristics of two Turkish lignites

The results of an experimental study aimed at evaluating the spontaneous combustion characteristics of two Turkish lignites moistured and air-dried at varying times are discussed. The spontaneous combustion characteristics of the coals were determined using Crossing Point Methods adapted to our laboratories conditions. The content of three predominant oxygen functional groups (carboxyl, hydroxyl, and carbonyl) of untreated, moisten and air-dried coal samples were also determined with wet chemical methods. The content of oxygen functional groups in moisten coal samples do not differ significantly that of untreated coal samples, for realized in vacuum desicator to moistured of coal samples. The liability of spontaneous combustion of the two coals was reduced when moisture content increased with increase in contacted time to water vapour. The moisten coal samples was dried in laboratory during 24 and 48 h time period. The concentration of oxygen contain functional groups of drying coal samples increased with increase of contact time with air and decrease of particle size. The liability of spontaneous combustion of the air-dried coal samples increased with increase of contacted time with air and with decrease of moisture content.     

煤调湿能效分析

根据实际运行数据,通过计算对以烟道气为热源的流化床煤调湿和以蒸汽为热源的回转窑煤调湿进行能效分析,指出不同热源煤调湿的节能特征和运行经济点,定量地分析煤调湿的节能减排效果,以指导煤调湿系统的优化运行。     

Chemical composition of glass and crystalline phases in coarse coal gasification ash

A procedure has been developed for determining the chemical composition and relative abundance of the amorphous or glassy material, as well as crystalline phases, present in coarse coal gasification ash, in order to assist in predicting the behaviour of the material in cement/brick/concrete applications. The procedure is based on a combination of quantitative X-ray diffraction (XRD), chemical analysis and electron microprobe studies.XRD analysis indicates that the clinker samples contain a number of crystalline high temperature phases, including anorthite, mullite, cristobalite, quartz and diopside. Quantitative evaluation using Rietveld-based techniques has been used to determine the percentages of both the individual crystalline phases and the glass component. These data were then combined with the chemistry of the crystalline phases and the overall chemical composition of the ash to estimate the chemical composition of the glass phase, which is typically the most abundant component present in the different materials.Although there is some degree of scatter, comparison between the inferred glass composition from XRD and bulk chemistry and actual data on the glass composition using electron microprobe techniques suggest that the two approaches are broadly consistent. The microprobe further indicates that a range of compositions are present in the glassy and crystalline components of the ashes, including Si-Al-rich glass, metakaolin and Fe-Ca-Mg-Ti phases, as well as quartz, anorthite and an aluminophosphate material. Electron microprobe and XRD studies also show that pyrrhotite (FeS), representing a high temperature transformation product of pyrite, is present in some clinker and partially burnt carbonaceous shale samples.     

一种新型煤炭风力分离及调湿技术

回顾了煤的风力分离和调湿技术的发展历史及现状,分析了该技术多年来没有得到广泛推广的原因。介绍了一种工艺设备简单、采用振动流化床、利用烟道气为换热介质的风力分离和调湿合一的煤的预处理工艺技术,文中详尽论证了该技术相对于已有相关技术所具有的突出特点。     

单种煤可捣固性能的研究

通过对6种不同煤化度煤的可捣固性能的研究发现,不同煤化度煤种的可捣固性能差别很大,中等煤化度的烟煤可捣固性能较好.同时以气煤和肥煤为研究对象,考察成型压强、水分含量及粒度组成对煤饼性能的影响后发现,最适宜成型压强在30MPa左右,各煤种都存在属于自己的最佳水分区间,粒度组成对煤饼性能的影响也十分显著.     

Significance of surface moisture removal on triboelectrostatic beneficiation of fly ash

The gas transport, triboelectrostatic beneficiation of coal combustion fly ash into carbon-rich and ash-rich products was studied relative to the effect of ash surface moisture. Increasing the humidity to which the ashes from American and Italian coal-fired utilities were exposed under process and ambient conditions affected carbon and ash separability. The effect of humidity and particle surface moisture became more important as particle size decreased: particles greater than 75 μm in diameter were nearly unaffected whereas particles smaller than 45 μm experienced up to a four-fold change in their separability upon changing their surface moisture contents. Although particle size influences the moisture adsorption, which in turn affects tribocharging, the decrease in adhesive forces between carbon and ash from otherwise intractable clusters during drying also may be a factor influencing triboelectrostatic beneficiation performance.     

Thermal properties, specific interactions, and surface energies of PMMA terpolymers having high glass transition temperatures and low moisture absorptions

We have prepared a series of poly(methyl methacrylate) (PMMA)-based terpolymers that have high glass transition temperatures and low moisture absorptions by the free radical copolymerization of methyl methacrylate, methacrylamide, and styrene in dioxane. We have investigated the effects of the styrene content on the glass transition temperatures, hydrogen bonding interactions, surface energies, moisture absorption, and molecular weights of these poly(methyl methacrylate-co-methacrylamide-co-styrene) (Poly(MMA-co-MAAM-co-S)) terpolymers by differential scanning calorimetry, Fourier transform infrared and X-ray photoelectron spectroscopies, contact angle measurements, and gel permeation chromatography. The results indicate that the glass transition temperatures, hydrogen bonding strengths, surface energies, molecular weights, and the moisture absorption decreased upon increasing the PS content in most of the terpolymer systems. In addition, the moisture absorptions of some selected terpolymers decreased even through they possess higher values of T_g than pure PMMA. These selected terpolymers have the potential to replace pure PMMA in optical device applications.     

入炉煤水分调节对焦炭指标及升温的影响

研究了入炉煤水分对焦炭冷热强度、粒度等的影响。比较了同高度装煤及同干煤量不同高度装煤条件下焦饼中心温度的差异。试验结果表明,当入炉煤水分减少时,干基成焦率提高,但焦饼收缩率降低,焦炭冷热强度改善,尤其是焦炭反应后强度提升明显,焦炭粒度呈减小趋势,焦炭均匀性改善;在保持相同干煤量的情况下,水分越少,升温速度越快。     

第三代煤调湿技术在生产实践中的应用

介绍了第三代煤调湿技术在生产实际应用中对炼焦和煤气净化系统生产带来的不利影响以及在节能方面的效果,同时进行原因分析并提出建议。