褐煤热水干燥改质后的性能研究

褐煤在我国煤炭能源中占有很大比重,因其含水量高、灰分大、容易风化、发热量低的缺点使褐煤的利用率较低。为了提高褐煤的利用率,采用高压釜热水干燥工艺对褐煤进行改质,并将改质的褐煤成型,研究其改质成型后的特性。实验结果表明：经热水干燥后褐煤中的水分、灰分、挥发分的含量有所降低,但固定碳和发热量有所提高;煤样粒度、干燥温度、成型压力对褐煤抗压强度的影响较为显著;热水干燥后褐煤的成型性明显增强,使煤球的抗压强度接近褐煤有粘结剂冷压成型煤球的强度,并且成本低于有粘结剂成型煤球的强度。     

基于SPSS分析褐煤热水干燥实验研究

为了发展褐煤综合利用技术和优化利用方法,应用正交筛选实验设计与均匀实验设计方法对霍林河褐煤进行了热水干燥的实验研究,并对正交筛选实验设计与均匀实验设计的结果应用SPSS11.5软件进行分析.确定了影响霍林河褐煤热水干燥的主要影响因素,大大减少了对高度不显著因素的实验研究,减少了实验次数,节约了实验成本和实验时间,并且确定了热水干燥主要影响因素与次要影响因素的最优实验水平.     

热水干燥技术处理舒兰褐煤的研究

介绍了热水干燥褐煤的方法及机理,在高压釜内加热干燥褐煤,可永久改变低阶煤的物理和化学性质,褐煤的最高内在水分显著下降,发热量提高,表面疏水性增强;利用干燥后的褐煤制备水煤浆,具有良好的成浆特性、流变特性及稳定性。     

印尼高水分褐煤干燥特性研究

以印尼高水分褐煤为试验对象,采用蒸汽管回转干燥技术对其进行静态、动态干燥试验研究。褐煤干燥速率特性试验表明,褐煤粒径和质量基本相同时,干燥蒸汽温度越高,水分蒸发速率越快,褐煤干燥速率越大;褐煤质量相同时,褐煤粒径越小,干燥时间越短,干燥速率越大;褐煤粒径相同时,褐煤质量越小,干燥时间越短,干燥速率越大;褐煤干燥速率曲线常在煤中水分低于空干基水分前出现拐点,即进入干燥降速阶段。通过对褐煤干燥前后的粒径分布、热稳定性分析可知,褐煤干燥过程伴随着细颗粒煤粉的产生,褐煤干燥后细颗粒煤粉增加了14.87%;褐煤干燥前后TS6分别为10.3%和19.2%,均属于低热稳定性煤,且干燥后褐煤的热稳定性好于干燥前;干燥后褐煤的反应开始温度RI和燃尽指数Cb分别降低了7℃和0.1112,相差较小,均极易着火和燃尽。     

褐煤高温烟气干燥过程中挥发分析出实验研究

对伊敏褐煤和大唐五间房褐煤在高温烟气环境下的干燥过程进行了实验研究.实验中对大粒径煤颗粒采用固定床干燥法,对小粒径煤粉则采用下降管顺流干燥法.根据实验获得的煤颗粒和干燥介质温度曲线研究了初始烟气温度、粒径和初始含水率对褐煤中水分和挥发分析出的影响,结果表明,褐煤高温烟气干燥过程主要分为预热阶段和降速干燥阶段,褐煤在下降管中的干燥过程主要处于预热干燥阶段;在800℃的烟气初温下,增大粒径,提高初始含水率,可以避免挥发分析出;两煤种在下降管干燥过程中均比较稳定,且伊敏褐煤相比五间房褐煤吸收和脱除水分更为容易,但也更易受热分解.研究表明,下降管高温烟气干燥技术适用于伊敏和大唐五间房褐煤这两种煤种的干燥过程.     

低煤阶煤的干燥进展

论述了目前各国所研究开发的几种低煤阶煤的干燥工艺；经比较认为热水干燥新工艺是一种较好的工艺，它能更好地提高低煤阶煤的利用前景。     

褐煤干燥技术综述

利用褐煤资源是我国能源发展的一项重要战略,大力研发与推广褐煤干燥提质技术,对提高褐煤使用效率,发展低碳经济有着非常重要的意义。介绍了煤干燥技术的分类,并对几种典型的褐煤干燥技术,如管式干燥、蒸汽管回转干燥、蒸汽流化床干燥、床混式干燥、热机械脱水等进行了比较。     

K-燃料~技术及其在燃煤发电中的应用

介绍了非蒸发式K-燃料褐煤干燥技术的工作原理;实验分析了提质后产品煤的水分及产品煤放置不同时间的回吸水量;在美国有关电厂燃烧发电的实践表明,燃烧干燥后的褐煤与优质煤效果相同,并且污染物排放量降低,可提高电厂整体经济性。     

褐煤综合利用中原料煤干燥特性研究

研究了褐煤资源高效综合利用中干燥时间、干燥温度、干燥方式等因素对原料煤性质,特别是粗褐煤蜡和腐植酸产率的影响。结果表明:原料煤的干燥需要在适宜的温度下和时间内进行,水分不是越低越好,否则不仅浪费能源和时间,还会影响主要产品的产率及品质。褐煤蜡产率与含水量之间存在重要的内在联系,即不同干燥条件下,水质量分数在10%—20%之间时,褐煤蜡产率均较高。同时,原煤在开采后允许进行一定时间的放置,除水质量分数降低外不会对原煤产生其他影响。建议在褐煤综合利用中,原料煤的干燥最好在100—150℃之间进行,调节干燥时间(需30—60 min),使水质量分数控制在10%—20%之间。     

褐煤干燥水分回收利用及其研究进展

褐煤干燥提质过程中的水资源化回收利用工艺技术可以提高煤阶并回收宝贵的水资源,降低干燥提质单元能耗。本文从介绍褐煤中水的存在形态出发,围绕烟气直接干燥、蒸汽流化床干燥、微波干燥、机械热压脱水干燥等工艺综述了近年来干燥水回收利用的研究现状和最新进展,讨论分析了褐煤干燥与水回收利用工艺的选择原则。在回收褐煤中丰富的水资源时,除了单纯考虑回收褐煤中的水资源,还应权衡褐煤干燥工艺、干燥温度和干燥介质、干燥水蒸气的余热利用方式以及干燥工艺上下游间的衔接等因素。基于目前褐煤资源的主要用途,将干燥尾气采用换热技术回收低温余热和干燥冷凝水直接净化处理后的二次回用技术将是以后的重要研究和应用方向。     

富氧条件下煤粉气流的着火性能变化

利用一维火焰炉对不同富氧条件下的煤粉气流着火燃烧特性进行了研究,得到了富氧条件下煤粉气流的着火性能变化规律。研究结果表明:随着助燃气体氧浓度的提高,各煤样的着火温度均大幅下降,其中低挥发分煤种在着火方面对富氧条件的改善更为敏感,即富氧条件的改善可减弱煤种间着火性能方面的差异性;随着氧浓度的提高,煤粉气流的着火方式明显从均相着火向非均相着火转变,其中燃用褐煤时发生着火方式转变所对应的氧浓度为50%~60%,燃用烟煤时约为40%,燃用贫煤和无烟煤时都约为30%;对于烟煤和褐煤,随着氧浓度的提高,对应的最佳煤粉浓度值先增大后减小,而对于贫煤和无烟煤,由于其在整个实验氧浓度范围内基本上都以"非均相着火"为主,因此随着氧浓度的提高,对应的最佳煤粉浓度的值基本上呈缓慢下降的趋势。     

Steric requirements for coal swelling by amine bases

A set of six coals ranging in rank from lignite to hvA bituminous was swollen with a series of alkyl-substituted pyridines and a smaller set of 4-alkylanilines. The size and branching of the alkyl groups was varied and the effect of this variation on the dissolution of the amines in the coal and the resulting coal swelling was measured volumetrically. In a few cases, substituents which hindered the amine nitrogen were studied. The lignite and subbituminous coal have a much higher tolerance to branched, bulky groups than do the bituminous coals. The presence of tertiary groups in a solute strongly inhibits their dissolution in bituminous coals. Bituminous coals behave as if extensive parallel packing of structures occurs. Often, they can accept very large planar groups but have a low capacity for branched groups.     

Floatability and desulfurization of a low-rank (Turkish) coal by low-temperature heat treatment

It is well known that higher rank coals are inherently hydrophobic whereas lower rank coals are more hydrophilic. Because of the hydrophilic character of low-rank coals, they are difficult to float even at high dosages of oily collectors. In the present study, the floatability behavior of a hydrophilic lignitic coal was investigated with and without low-temperature heat treatment using a column flotation and a Denver flotation cell. The floatability and hydrophobicity of the coal were investigated upon heating the coal at 105 °C. After heating it was found that the floatability, hydrophobicity, and separation efficiency of lignite increased dramatically. A change in the hydrophobicity of lignite before and after the low-temperature heating was determined by FTIR spectroscopy. On the other hand, reverse flotation experiments applied in natural, alkaline, and acidic conditions yielded rather good results. A concentrate assaying 1.52% total sulfur was obtained at natural pH from a feed of 2.50% sulfur.     

高砷褐煤与低砷烟煤混燃砷的挥发特性及模型

选取典型的高砷褐煤和低砷烟煤,在一维等温燃烧实验台上进行混燃实验,研究温度（600～1100℃）和掺混比（3:1、1:1、1:3）对高砷褐煤混燃砷挥发的影响。实验结果表明：随着温度的升高,单煤及混煤燃烧砷的挥发比例逐渐增大,不同温度下混煤燃烧砷的挥发比例介于两个单煤之间,但砷的挥发比例并不是简单的加权平均,不同温度和掺混比下混煤砷的挥发比例均高于加权值,高砷褐煤中较高的挥发分含量在影响混煤焦炭燃烧的同时也促进了混煤中砷的挥发。因此,提出了综合考虑温度、掺混比和高砷褐煤影响的混煤砷挥发模型,不同温度和掺混比下的模型计算结果与实验值吻合度较好。     

Catalysis of carbon-steam gasification by ash components from two lignites

Ash transfer from a reactive to a less reactive coal is an interesting possibility for improving and equalizing gasification characteristics of coals. To assess the catalytic action of coal impurities in the steam gasification of carbon, three approaches were used. In the first series, the effects of different coal ashes on the gasification kinetics of graphite were compared. A parallel study was made by adding lignite ash to a coal of low reactivity. Finally, gasification rates of chars prepared from demineralized coals were measured. While it was found that ash from reactive coals can significantly enhance the gasification rates of chars derived from coals of lesser reactivity, it was not possible to distinguish clearly between a catalytic lowering of the activation energy and an increase in the number of gasification sites. The gasification enhancement by lignite ash may open practical possibilities for blending coals of different reactivity, and warrants further study to identify the constituents associated with this effect.     

Liquefaction and/or solubilization of Spanish coals by newly isolated microorganisms

A screening procedure has been set up for isolating microorganisms capable of liquefying coal. Spanish coals were used in the tests, namely a brown lignite from Galicia, sub-bituminous coal from Teruel and hard coal from Minas Figaredo S.A. (Asturias). Among the isolated strains several microorganisms proved capable of liquefying untreated lignite. When lignites were pretreated a more intense and rapid liquefaction was achieved, chelating agents being among the best pretreatments. None of the isolated microorganisms could satisfactorily liquefy sub-bituminous and hard coals in solid media. On the other hand, some fungi grew specifically on the untreated coals, engulfing them and in many cases a soft slurry was obtained. Several of the isolated microorganisms were able to solubilize all three untreated Spanish coals in liquid media. Coal solubilization was measured spectrophotometrically at 300, 400 and 450 nm.     

Temperature dependence of crosslinking processes in pyrolysing coals

Changes in the macromolecular structure of a lignite and a bituminous coal during rapid pyrolysis in the temperature range 300–1200 K are described. Solvent swelling techniques have clearly demonstrated that crosslinking occurs in lignites at somewhat lower pyrolysis temperatures than it does in bituminous coals. The onset of the crosslinking processes in bituminous coals coincides with the end of the tar formation period. In lignites, crosslinking occurs very early in the pyrolysis process, coinciding with low temperature release of CO₂. The presence of natural moisture in the lignite appears to have a significant effect on pyrolysis chemistry, increasing the amount of crosslinking observed at any temperature.     

Principal component analysis of upgraded Western Canadian coals

Three Western Canadian coals with different ranks have been upgraded by evaporative drying in several atmospheres at temperatures up to 500°C. Data from proximate and ultimate analyses, along with equilibrium moistures and heating values, have been evaluated by principal component analysis. The results indicate that significant changes in the products occur above 400°C for lignite and above 300°C for subbituminous B and high-volatile C bituminous coals. No significant differences are observed when the data for the upgraded coals are compared with published data for naturally occurring Western Canadian and US coals of the same rank.     

Chemical reduction of sulphur dioxide to free sulphur with lignite and coal. 2. Kinetics and proposed mechanism

The reactivity of lignite and different ranks of coal with sulphur dioxide has been investigated in a corrosive-gas, thermogravimetric reactor system. With all coals, the reaction occurred in two distinct stages. A rapid initial stage was controlled primarily by the devolatilization rate of the coal. The second stage limited the overall rate and was controlled by surface properties of the coal char. The portion of lignite associated with the second stage of reaction exhibited a much higher rate of SO₂ reduction than the corresponding material from all other coals. Correlation of the data showed an inverse relation between the reactivity of coal chars and the relative rank of the parent coal. Activation energies associated with the reduction of SO₂ by the coal chars increased slightly from 134 kJ mol^?1 for lignite char to 150 kJ mol^?1 for HVB bituminous coal char. The higher reactivity of lignite or lower-rank coals was due in part to entropy factors or available catalytic sites on the surface of coal. Formation of a thermally stable CS complex on the surface of coal appeared to poison the surface and thus limit further reaction. Alkali and alkaline earth metals in lignite served as active sites for catalysing the reaction of SO₂ with the CS complex and thus enhanced the rate of SO₂ reduction with lignite.     

Mineral matter and elemental concentrations in selected western canadian coals

Major and trace element analyses were performed on coals from various locations in western Canada, and on low-temperature (150 °C) and high-temperature (1000 °C) coal ash produced from these coals. Elemental analyses were carried out by X-ray fluorescence spectroscopy and intense neutron activation analyses. Based on their trace elements, the coals in this study fall into two groups: 1. low-rank coals (lignite-subbituminous) of late Cretaceous and Tertiary age; and 2. high-rank coal (bituminous-semianthracite) of Jurassic-Cretaceous age. The elemental analyses of the coals and coal ash indicate that the local conditions had considerable influence on the concentrations of certain trace elements.Antimony and selenium in coals are the only elements which are enriched relative to concentrations in the earth's crust; arsenic is concentrated in lignite to subbituminous coal, but is depleted in bituminous-anthracite coals; as expected the ash of these coals showed many more instances of enrichment.