共查询到20条相似文献,搜索用时 0 毫秒
1.
2.
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. 相似文献
3.
4.
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。 相似文献
5.
6.
7.
8.
9.
Dehua Liang Jiguang Huang Yuntao Zhang Zheng Zhang Haiping Chen Heng Zhang 《Journal of the European Ceramic Society》2021,41(11):5696-5710
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. 相似文献
10.
11.
Kamalesh S. Bhambare 《Fuel Processing Technology》2010,91(5):566-571
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, NOx 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. 相似文献
12.
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. 相似文献
13.
14.
Chemical composition of glass and crystalline phases in coarse coal gasification ash 总被引:1,自引:0,他引:1
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. 相似文献
15.
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。 相似文献
16.
17.
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. 相似文献
18.
Jem-Kun Chen 《Polymer》2005,46(7):2354-2364
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 Tg than pure PMMA. These selected terpolymers have the potential to replace pure PMMA in optical device applications. 相似文献
19.