高硫石油焦配煤可磨性规律及粒度分布研究

选取HGI相差较大的两种高硫石油焦B、C和一种淮北煤A按不同比例进行配煤,测定煤样、高硫石油焦样和配煤样品的HGI,采用行星式球磨机将样品（0.63 ～ 1.25 mm）磨制5min,并分析粒度分布.结果表明,在难磨的石油焦中配人一定比例的易磨煤可以提高配煤的HGI;难磨石油焦B与A煤混配后的HGI与配煤比例能够很好地遵循线性可加原则,易磨石油焦C与A煤混配后的HGI与配煤比例线性关系很差;随着配煤中石油焦的比例增加,大颗粒所占的比例增多.     

混煤可磨性指数(HGI)可加性研究

对比了单煤及两两混煤可磨性指数(HGI)的实测值与计算值,说明同一配比、不同混煤的实测值与计算值不完全相等,存在一定误差。分析了存在偏差的主要原因为:实验本身的系统误差和单煤之间可磨性指数(HGI)不具有线性可加性。最后通过t检验验证可磨性指数(HGI)实测值与计算值之间的差异是否显著。结果表明:同一配比、不同混煤时,大量难磨煤与少量易磨煤组成的混煤可磨性指数(HGI)实测值与计算值具有显著性差异;其它配比条件下,不同混煤实测值与计算值之间差异性不明显。同一混煤、不同配比时,混煤可磨性指数(HGI)实测值与计算值之间误差不全在正常范围内,混煤可磨性指数(HGI)与配比不全具有线性相关性。单煤可磨性指数(HGI)不具有线性可加性。     

不同区域气煤对焦炭质量的影响研究

针对气煤配用量对焦炭质量的影响，通过来自不同产地4种气煤的各项指标进行分析检测并将气煤按一定比例进行配煤炼焦实验，考察了其变质程度、基式流动度及碱度催化指数对焦炭热态的影响。试验结果表明：气煤的变质程度及基式流动度特征指标对焦炭热态性能影响较大，碱度催化指数影响次之。为炼焦配煤选择气煤品种和制定配煤比例提供了技术依据，对实际生产应用具有一定的指导意义。     

煤磨碎性能与煤质特性的相关性研究

采用多元统计方法对煤质特性与可磨性HGI的相关性进行了研究.结果表明,水分和挥发分越高,HGI越低;灰分和固定碳含量越高,HGI越高.但HGI与煤质特性存在明显的非线性.国外文献提供的非线性预测方程不适合我国煤种.仅从煤的工业分析等化学组分出发,将其看作一种均匀的物质,不能科学地反映煤的可磨性.煤的显微组分、矿物质类型、颗粒大小和分布以及煤种的显微构造等物理参数是决定煤可磨性能的重要因素.     

不同变质程度炼焦煤最佳活惰比研究

为定量描述不同变质程度炼焦煤最佳活惰比的差异,以10种单煤添加不同比例的惰性物炼制焦炭,考察焦炭显微强度(MSI)随活、惰组分比例的变化规律。研究表明,10种单煤炼制的焦炭显微强度(MSI)随活惰比变化呈现3种变化规律。采用两种数学模型,对单煤的最佳活、惰组分比例与变质程度变化规律进行拟合,论证了高斯曲线模型为描述不同变质程度煤最佳活惰比变化规律的最优数学模型,据此可得出不同变质程度煤最佳活惰比。     

干煤粉气化炉原料煤掺配高硫石油焦气化适应性研究

针对目前高硫石油焦利用率低的问题,选取两种典型高硫石油焦（JL、US）分别与AQ006煤掺配,考查了掺配两种焦的可磨性、灰熔融特性、黏温特性、CO2反应性,并进行了气化模拟计算。结果表明：两种石油焦具有低灰、低挥发分、高硫、高发热量等特点,且两种焦在不同掺配比例下,配煤的可磨性指数均高于80,是优质的粉煤气化配煤原料。AQ006煤分别掺配两种焦的灰熔融温度均高于1500℃,添加石灰石可有效降低掺配质量分数25%JL焦和US焦（焦∶煤=1∶3）的配煤灰熔融温度至1 400℃以下,且在石灰石质量添加量为6%时,两种掺配焦的高温灰渣黏度在2～25Pa.s的温度区间都高于200℃,满足Shell气化炉操作要求。与单独JL焦、US焦相比,配煤的CO2反应性显著提高。模拟计算结果表明掺配石油焦加助熔剂方案与中国石化安庆分公司Shell气化炉现用配煤方案相比,有效气产量增大,比氧耗和比煤耗有所下降。     

煤的水分与煤可磨性的关系分析

选取3种不同变质程度的煤作为研究对象,测定不同水分条件下煤的可磨性指数,结果表明煤的可磨性指数主要与煤的变质程度有关,不同变质程度煤的可磨性指数与水分存在一定的线性关系,但其变化规律并不是很显著。     

高温气化过程中降低煤灰熔点的实验研究

高灰熔融性好的寨崖底矿煤分别与低灰熔融性的露天煤、府谷煤按不同配比混合,制成2种配煤灰样,用HR-4灰熔点测定仪分别测定其在氧化性气氛和弱还原性气氛下的熔融特征温度。结果表明,配煤能有效改善煤灰熔融特性,但配煤灰熔融性变化与配比之间是非线性关系,弱还原性气氛下配煤改善效果显著。以硼砂作为助熔剂,按不同比例添加到高灰熔点煤潞安矿中,在弱还原性气氛下测定混煤灰熔融温度,结果表明添加少量比例的硼砂可以显著降低煤灰熔融性温度。对混煤灰进行的X-射线衍射实验表明,煤灰中矿物质形态的变化是混煤灰熔点降低的直接原因。     

不黏煤的煤质分析与配煤实验

对陕西的一种不黏煤进行了分析,开展了捣固配煤实验。结果显示,该煤低灰、低硫、变质程度低、无黏结性,直接替代原来的弱黏煤会降低焦炭强度。通过调整配煤结构,增加配合煤胶质体数量,在捣固炼焦中配用比例达到8%,可以保证焦炭质量稳定,不仅降低了成本,还拓展了煤源。     

焦炭质量的影响因素分析

从影响焦炭质量的配合煤性质和工艺条件两个方面,分析了煤种的灰分和硫分对焦炭化学性质的影响,以及煤种的挥发分、粘结性和生产工艺对焦炭强度性能的影响。配入榆林低变质煤可以有效降低焦炭的灰分和硫含量,但其几乎没有粘结性,因此,配煤时要分析各煤种的粘结性和结焦性指标,以确定低变质煤的配入量并不影响焦炭的强度要求。     

配合煤配比对焦炭综合热性质的影响

以企业生产实践为背景,研究在配合煤中增配肥煤和1/3焦煤对焦炭综合热性质的影响。对不同配比配合煤的性质指标进行检测,采用40 kg焦炉实施炼焦试验,并对炼制焦炭的传统国家标准热性质指标和利用自主研制装置测得的综合热性质指标进行测定。结果表明:增配肥煤和1/3焦煤,均会使配合煤的变质程度降低,挥发分含量升高,胶质体的黏结能力下降,但胶质体的量保持不变。配比变化引起的配合煤性质指标的变化没有显现在焦炭的传统国家标准热性质指标反应性CRI和反应后强度CSR上。以往的研究都是以CRI和CSR指标为目标量判断配合煤的配比是否合适,本研究除此之外还采用了自主提出的焦炭综合热性质指标。配合煤配比变化引起的焦炭的综合热性质指标变化比国家标准热性质CRI和CSR指标变化敏感,这可能与其反映了焦炭某些新的特征有关。基于焦炭综合热性质指标的变化规律,考虑到1/3焦煤具有经济性,生产上增配某些特定的1/3焦煤,可以同时达到提高焦炭质量和降低配煤成本的目的。     

混煤燃烧过程中的交互作用:过量空气系数对混煤燃尽特性的影响

在沉降炉上对无烟煤、贫煤、烟煤、褐煤以及不同配比(25%、50%、75%)混煤开展了过量空气系数对混煤燃尽特性影响的实验研究。结果表明,混煤燃烧中挥发分高的煤对挥发分低的煤存在促进和抑制2种交互作用。"炉外"掺烧方式下,低挥发分煤与高挥发分煤掺混时,抢风抑制作用表现明显;尤其是掺烧75%高挥发分煤时,抢风抑制作用最为显著;提高过量空气系数可以改善贫氧气氛,减弱混煤燃烧中的抢风抑制作用,提高混煤燃尽率。"炉内"掺烧方式下,过量空气系数的增加,交互作用减弱,各单煤的燃烧独立性增强,混煤燃尽率逐渐接近计算线性燃尽率。     

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。     

An investigation of the grindability of two torrefied energy crops

The process of torrefaction alters the physical properties of biomass, reducing its fibrous tenacious nature. This could allow increased rates of co-milling and therefore co-firing in coal fired power stations, which in turn would enable a reduction in the amount of coal used and an increase in the use of sustainable fuels, without the need for additional plant. This paper presents an experimental investigation of the pulverisation behaviour of two torrefied energy crops, namely: willow and Miscanthus. A multifactorial method approach was adopted to investigate the three process parameters of temperature, residence time and particle size, producing fuels treated using four different torrefaction conditions. The untreated and torrefied fuels were subjected to standard fuel analysis techniques including ultimate analysis, proximate analysis and calorific value determination. The grindability of these fuels was then determined using a laboratory ball mill and by adapting the Hardgrove Grindability Index (HGI) test for hard coals. After grinding, two sets of results were obtained. Firstly a determination similar to the HGI test was made, measuring the proportion of sample passing through a 75 μm sieve and plotting this on a calibrated HGI chart determined using four standard reference coals of known HGI values. Secondly the particle size distributions of the entire ground sample were measured and compared with the four standard reference coals. The standard fuel tests revealed that temperature was the most significant parameter in terms of mass loss, changes in elemental composition and energy content increase. The first grindability test results found that the untreated fuels and fuels treated at low temperatures showed very poor grindability behaviour. However, more severe torrefaction conditions caused the fuels to exhibit similar pulverisation properties as coals with low HGI values. Miscanthus was found to have a higher HGI value than willow. On examining the particle size distributions it was found that the particle size distributions of torrefied Miscanthus differed significantly from the untreated biomass and had comparable profiles to those of the standard reference coals with which they had similar HGI values. However, only the torrefied willow produced at the most severe conditions investigated exhibited this behaviour, and the HGI of torrefied willow was not generally a reliable indicator of grindability performance for this energy crop. Overall it was concluded that torrefied biomass can be successfully pulverised and that torrefied Miscanthus was easier to grind than torrefied willow.     

用于混煤燃烧控制砷排放模型研究

混煤掺烧是控制燃煤砷排放的有效方式,但由于缺乏相关的配煤模型,限制了该技术的应用。根据燃煤过程中砷的挥发释放机制,提出一种采用砷的释放指数P表征煤燃烧过程砷的释放特性的配煤模型。该模型综合考虑煤的灰分、灰中主要矿物元素含量、各矿物元素对砷的固定系数以及煤中砷含量等因素。研究结果表明,随着煤灰固定系数由23.12增至50.90,煤灰的气相砷吸附量由3.39 mg/g增至6.14 mg/g;随着释放指数P增大,砷的固定率减小,且随着温度升高,两者相关性由900℃的0.67增至1 300℃的0.86。根据P值筛选煤种进行掺烧,当掺混煤种P值差异较大时,掺烧低P值煤种不仅可降低混煤中的砷含量,还能促进高P值煤的砷在灰中富集,促进率达77.14%;掺混煤种P值差异较小时,掺烧低P值煤种会促进砷的释放。本模型可较好地筛选煤种,为混煤掺烧控制砷等痕量元素的排放提供了新的思路。     

一种确定配煤最佳比例的简易方法探索

采用奥亚膨胀仪测定2种不同配比煤的b值,利用数学方法推算出最佳配比,并对最佳配比进行实验室炼焦验证。结果表明,利用奥亚膨胀仪结合数学方法推算出的2种煤最佳配合比例基本正确,但对某些惰性物较少且挥发分较高的中低变质煤种配合时存在反常现象。此方法也可适用于3种以上煤推算最佳配合比例,但误差可能会增大。     

Experimental study on interaction and excess heat release under oxy-fuel combustion of blended coals

The combustion behavior and excess heat release during the oxy-fuel combustion of blended coals were investigated experimentally using a non-isothermal thermogravimetric analyzer. The atmospheres were set to 10%O₂/90%CO₂, 21%O₂/79%N₂, 30%O₂/70%CO₂, and 50%O₂/50%CO₂, and Arthur coal (bituminous coal, BA) and KPU (sub-bituminous coal, SK) were selected as fuel with blending ratios of BA25%/SK75%, BA50%/SK50%, and BA75%/SK25%. The purpose of this study is to investigate the interaction between the blended coals and the effects of blending ratio and oxygen concentration on the excess heat release under oxy-fuel combustion. The results showed that as the oxygen concentration and proportion of sub-bituminous coal increased, the peak value in the differential thermal analysis curve increased by the enhanced reaction rate. A higher oxygen concentration led to excess heat release. The ignition temperatures depended on the volatile matter content of the sub-bituminous coal, whereas the burnout temperature was largely affected by the fixed carbon content of the bituminous coal. For interaction behaviors on characteristic temperatures, the volatile release temperature shows an additive behavior; however, ignition and burnout temperatures show non-additive behaviors for blended coals.     

Prediction of grindability with multivariable regression and neural network in Chinese coal

Grindability index of coal is usually determined by Hardgrove Grindability Index (HGI). The correlation between the proximate analysis of Chinese coal and HGI was studied. It was found from statistical analysis that, the higher the moisture and the volatile matter content in coal, the less the HGI will be. On the contrary, the higher the ash and the fixed carbon content in coal, the higher the HGI will be. But the correlation between proximate analysis and HGI in coals is nonlinear. The prediction equation of HGI reported in literature, which is based on proximate analysis of coal and linear regression method, is not correct for coals in China. In this paper, the generalized regression neural network (GRNN) method was used to predict the HGI. A higher precision in the prediction result was obtained through such new method. By this method, the HGI can be estimated indirectly from the proximate analysis of coal when the HGI measurement equipment is not available.