Study on Direct Reduction Characteristics of Iron Ore Coal Mixed Pellets

In order to get DRI iron ore coal mixed pellets are reduced isothermally. The mechanisms of reduction desulphurization, iron oxide reduction and the structure regenesis of the coal mixed pellets during reduction have been studied. The effect of various processing factors on the quality of DRI and economy technological indices including compression strength, desulphurization rate, recovery rate, reaction fraction, carbon content and metallization are also researched.

Study on the Evaporation Kinetics of Zinc and Lead in Zn-Pb-Bearing Dust Pellets Mixed with Coal Powder

The study on the evaporation kinetics of zinc and lead in the pellets made of ZnPbbearing dust mixed with carbon ,in nitrogen atmosphere at the temperature range between 1 100 and 1 300 , shows that the reduction temperature has a significant effect on the evaporation rates of zinc and lead and that both the particle size of coal powder and the extra carbon content have no effect on the evaporation rates . The obtained activation energies for the evaporation of zinc and lead are 7942 kJ/mol and 8874kJ/mol respectively. The evaporation rate of zinc is controlled by the reaction between zinc oxide and CO while that of lead is controlled by lead volatilization and the diffusion of gaseous lead through gas boundary layer covering the surface of liquid lead.

Guidance method to use mixed coal in blending for coking

Based on the principle that the adaptation can be reflected by the overlap of reflectance distribution peaks,the effect of various types mixed coal for coking is analyzed.Based on the action of the vitrinite of different reflectance range and the adaptation,a new method for guidance blending coal is established.Through simulation,blending coal using the software of HD automatic microscope photometer,makes the synthetic blending coal reflectance distribution map to nothing notch wide single peak flat-shaped symmetrical distribution,blending coal random reflectance meets 1.1 - 1.2,the standard deviation meets 0.35 - 0.4.It is based on the conditions that active component in the blending is excessive.Using this method,the mixed coal can be used as much as possible and play a positive role.The problem about implementation process is discussed.

A study on mixed coal simulation soft layer of gas adsorption

Based on the single coal adsorption gas, hard coal and soft coal of intake airway in Shanxi Heshun Tianchi Coal Mine were chosen to simulate the soft coal seams in coalbed as those in different qualities are mixed with delamination. Experiments on characteristics of adsorption gas of hard coal and soft coal in different quality ratios were done according to the Langmuir single molecule layer absorption theory. Gas constant mensuration instrument WY-98B was used during the experiments. Isothermal adsorption curves, adsorption constants a and b of the mixed coal samples in different quality ratios were established for qualitative and quantitative analysis. The relationship curves of adsorption quantity with changing pressure and variation equation of adsorption constants a, b with changing thickness ratio shows that the thickness of soft layer and hard coal approximately equal, thus resulting in outburst at greatest risk, then a theoretical base for the mechanism of coal and gas outburst has been put forward and a technical support scheme for engineering control of gas outburst is laid out.

Quantitative identification of coal-type gas and oil-type gas in source-mixed gas at the northern margin of Qaidam Basin

The current study tested the gas component and carbon isotopic composition of gas samples from 6 oilgas fields at the northern margin of Qaidam Basin, and established a chart to quantitatively identify the mixing ratio of source-mixed gas. Besides, this research quantitatively investigated the natural gas generated by different types of organic matter. The results show that different ratios of source-mixed gas exist in the 6 oil-gas fields at the northern margin of Qaidam Basin. Among them, Mabei has the highest mixing ratio of coal-type gas, followed by Nanbaxian, Mahai, Lenghu-4, Lenghu-3 and Lenghu-5, with the ratios of coal-type gas 91%, 87%, 83%, 66%, 55% and 36%, respectively. Lenghu-3 and Lenghu-4 oil-gas fields were mainly filled by coal-type gas earlier. For Lenghu-3, the gas was mainly generated from low matured source rocks in lower Jurassic Series of Lengxi sub-sag. For Lenghu-4, the gas was mainly generated from humus-mature source rocks in lower Jurassic Series of the northern slope of Kunteyi sub-sag. Gas in Lenghu-5 was mainly later filled oil-type gas, which was generated from high matured sapropelics in lower Jurassic Series of Kunteyi sub-sag. Earlier filled coal-type gas was the main part of Mahai, Nanbaxian and Mabei oil-gas fields. Gas source of Mahai was mainly generated from high mature humics in lower Jurassic Series of Yibei sub-sag; for Nanbaxian, the gas was mainly generated from high matured humics in middle-lower Jurassic Series of Saishiteng sub-sag; for Mabei, the gas was mainly generated from humus-mature source rocks in middle Jurassic Series of Yuqia sub-sag.

Experimental Study on Ammonia Co-Firing with Coal for Carbon Reduction in the Boiler of a 300-MW Coal-Fired Power Station

To reduce CO_(2) emissions from coal-fired power plants,the development of low-carbon or carbon-free fuel combustion technologies has become urgent.As a new zero-carbon fuel,ammonia(NH_(3))can be used to address the storage and transportation issues of hydrogen energy.Since it is not feasible to completely replace coal with ammonia in the short term,the development of ammonia-coal co-combustion technology at the current stage is a fast and feasible approach to reduce CO_(2) emissions from coal-fired power plants.This study focuses on modifying the boiler and installing two layers of eight pure-ammonia burners in a 300-MW coal-fired power plant to achieve ammonia-coal co-combustion at proportions ranging from 20%to 10%(by heat ratio)at loads of 180-to 300-MW,respectively.The results show that,during ammonia-coal co-combustion in a 300-MW coal-fired power plant,there was a more significant change in NO_(x) emissions at the furnace outlet compared with that under pure-coal combustion as the boiler oxygen levels varied.Moreover,ammonia burners located in the middle part of the main combustion zone exhibited a better high-temperature reduction performance than those located in the upper part of the main combustion zone.Under all ammonia co-combustion conditions,the NH_(3) concentration at the furnace outlet remained below 1 parts per million(ppm).Compared with that under pure-coal conditions,the thermal efficiency of the boiler slightly decreased(by 0.12%-0.38%)under different loads when ammonia co-combustion reached 15 t·h^(-1).Ammonia co-combustion in coal-fired power plants is a potentially feasible technology route for carbon reduction.

某1000MW燃煤锅炉掺烧污泥安全经济分析

某1000MW燃煤锅炉长期掺烧污泥和褐煤,锅炉效率有所降低,停炉检修时发现燃烧器附近的水冷壁和一级过热器管屏存在结渣情况.为了提高锅炉效率和解决结渣问题,开展了常用煤种与常用污泥的燃烧特性试验,并且结合制粉系统和燃烧调整试验,优化炉内燃烧工况.结果表明:优化后的燃烧工况能有效实现炉膛燃烧“风包粉”,成功消除了水冷壁区域和一级过热器管屏的结渣问题.此外,针对锅炉不同负荷工况,提出了基于二次风配比和过量空气系数控制的污泥掺烧策略,以进一步提高锅炉效率.

燃烧氢氨能源的清洁环保供热及减少碳排放量

介绍了零碳排放燃料氢能源与氨能源的优点,分析比较氢能与氨能的运输、储存、安全性、经济性、相互转化、相互融合、混合燃烧等特性。研究了燃烧氢气导热油炉的结构型式,互相比较各种常见能源的碳排放量,讨论了发电厂燃煤锅炉混合燃烧氨气的减少碳排放技术。展望氢能源与氨能源中应用成长较快的行业领域发展前景。

Pyrite Formation in Organic-rich Clay, Calcitic and Coal-Forming Environments

The early diagenetic characteristics of pyrite formation processes in a Miocene freshwater sequence of mixed sediments （coal fragments in clays, sandstones or shales） alternating with continuous brown coal layers was investigated. Based on abundant minerals, the following main sedimentary environments were distinguished： the illite-montmorillonitic （I-M）, calcitic （Ct） and coal-forming environment （CL）. For these hydrogeochemically differing environments the effects of limiting factors on the pyrite formation process （availability of sulphate and Fe, amount of organic matter and participation of organic sulphur） were assessed by correlation analysis. Significant differences in the effects of these limiting factors in the particular environments were observed. These differences were explained taking in account the different oxidative activity, Fe-complex and surface complex forming properties of humic substances in dependence of pH of environment and the abundance of sorptionally active clay minerals. In environments having a relatively low pH and containing clay minerals （I-M- and CL-environments） the oxidative activity of humic substances （Hs） on pyrite precursors was greatly prevented however pyrite formation depended on reactive Fe availability as the consequence of complex formation. On the contrary, in environments with a relatively high pH, as it was the calcitic, the oxidative activity of Hs was greatly enhanced, thus oxidizing the sulfur precursors of pyrite. The oxidation degree of organic matter was probably also a consequence of the differing activity of the humic electron-acceptors.

模拟暗湿工况下煤矸混合体态势热敏图像精准辨识实验

煤矸井下智能分选作为智慧矿山建设的重要组成,可有效提升矿井资源绿色利用。现阶段可见光图像识别技术针对井下昏暗潮湿环境中煤矸混合体的辨识还有待完善。基于热红外成像技术和改进YOLOv5算法模型,提出了一种暗湿工况下煤矸混合态势热敏图像辨识方法。将YOLOv5模型的Neck部分改用加权双向特征金字塔(BiFPN)结构,通过多层次特征融合提高煤矸的辨识效率,采用CIOU函数作为损失函数,提升煤矸检测精准率;构建了煤矸混合体热敏采集实验平台,模拟了井下密闭空间低照度、高湿度、高风速环境,通过CLAHE与LAPLACE算子对红外摄像机所采集的热敏图像进行对比度增强和边缘强化预处理,以不同数据集、不同改进模块、不同算法模型等多个角度系统分析了煤矸混合体态势热敏图像辨识结果,探究了湿度变化对暗湿工况下煤矸识别准确率的影响规律。研究结果表明:预处理后的图像平均精准率较原始图像提升了1.7%,F-Measure提升了6.9%;改进后的YOLOv5模型平均精度均值和F-Measure达到了80.2%与84.6%,高于经典模型的74.6%与79.7%,可有效提升煤矸热敏图像检测精度;环境相对湿度与识别准确率呈现先正相关待湿度达到一定阈值后负相关的变化规律。提出了热敏图像可准确识别昏暗潮湿密闭环境中的煤矸混合体,为实现井下暗湿工况煤矸混合态势精准辨识提供了科学依据。

瓦斯煤尘及其混合物着火爆炸特性研究进展

煤尘、瓦斯及其混合物广泛存在于煤矿、冶金等粉尘涉爆行业场所中,其着火爆炸特性各异。基于广泛的文献调研,系统研究了煤尘、瓦斯及其混合物等3种不同可燃物着火爆炸特性的测试方法、实验结果及影响因素;分析了研究爆炸特性对于预防和减轻工业环境中瓦斯和煤尘爆炸相关灾害的重要性。分析结果表明:即使瓦斯和煤尘浓度低于其爆炸下限值,混合爆炸仍可能发生,混合物通常具有更高的爆炸严重性和爆炸敏感性;瓦斯、煤尘及其混合物的爆炸特性受瓦斯煤尘浓度、实验环境条件及煤粉的物理化学性质等多种因素的影响。未来,瓦斯煤尘及其混合物着火爆炸探索的重点包括化学动力学、爆炸抑制和缓解措施,以及特殊条件下的着火爆炸特性等。

智能放煤理论与技术研究进展

综放开采技术是厚及特厚煤层开采的有效方法,已成为我国在世界煤炭开采行业的标志性技术。综述了“四要素”放煤理论、顶煤采出率与含矸率关系、基于块度分布的采出率预测模型、煤流瞬时含矸率-累计含矸率关系等智能放煤理论研究进展。分析了智能放煤技术难点,指出含矸率是影响顶煤采出率和煤质的关键因素,放煤过程中含矸率的快速、准确计算是智能放煤技术突破的重点和关键。将智能放煤技术分为非图像识别智能放煤技术和图像识别智能放煤技术2类,对不同技术的研究进展、优缺点及使用条件进行了详细分析。非图像识别智能放煤技术包括记忆放煤技术、声音振动信号识别技术、γ射线探测技术、探地雷达技术、微波照射+红外探测技术、激光扫描放煤量监测技术等,图像识别智能放煤技术包括井下照度环境精准控制、放煤图像去尘算法、含矸率计算精度保障策略、煤岩红外图像识别等。

某350 MW机组对冲锅炉燃用高碱煤炉膛腐蚀防治研究

为降低燃料采购成本,保证燃料供应,甘肃某电厂大比例掺烧了部分新疆高碱的广汇煤和新疆能源煤。高碱煤掺烧后,锅炉出现较严重的受热面高温腐蚀和结焦现象,负荷最高只能带到85%ECR。为减轻高温腐蚀,对锅炉开展了煤质特性、燃烧优化调整和设备改进技术研究。结果表明:锅炉燃用较低硫份煤的情况下仍然发生较严重的高温腐蚀,主要与新疆煤中的钠、钙等碱金属及氯质量分数较高有关,通过提高氧量、降低一次风量、减弱燃烧器外二次风旋流强度和开大贴壁风等运行调整手段,可以一定程度上改善水冷壁高温腐蚀特性;彻底解决该问题,还需使用添加剂、进行防高温腐蚀喷涂、增加吹灰器、改进贴壁风和燃烧器设计等技术途径。该研究成果可为解决高碱煤掺烧过程中出现类似问题的电厂提供借鉴和参考。

基于收敛性提升的粒子群算法及其在火电厂配煤优化研究

针对大型火电机组的燃煤煤种复杂、混煤掺烧决策困难的现状,以及配煤优化过程存在多种设计约束和物理约束而导致传统优化算法的寻优过程难以收敛的问题,提出了一种改进粒子群优化算法。该算法将自适应约束处理机制引入传统粒子群优化算法中,基于距离测度和自适应惩罚项对违反约束的粒子进行自适应处理,引导寻优过程实现收敛;同时,采用平滑非线性权重递减策略代替传统粒子群优化算法的定值惯性权重设置方法,防止算法的寻优过程陷入局部最优。基于现场数据的仿真结果表明,所提算法在存在多约束条件的非线性函数寻优过程中具有明显优势,能够实现不同评价指标的均衡优化。

低能耗CO_(2)混合胺吸收剂复配筛选与工业验证

在如今温室效应日益严重背景下,化学吸收法作为当前最具应用前景的燃煤烟气脱碳技术,受国内外广泛关注,开发低再生能耗、高稳定、易工程化应用的吸收剂是目前研究热点。提出了以高容量、低能耗三级胺为吸收剂主剂,高动力学一级胺和高稳定环状胺为辅剂吸收剂方案;并形成了从实验室配方遴选、百标方时中试工艺匹配到每年万吨级规模工业装置运行优化的工程化开发体系。通过鼓泡吸收试验与吸收-再生循环试验对吸收剂进行快速筛选,初筛获得一种性能好的吸收剂配方,通过200 m^(3)/h中试与万吨级工业装置测试优化运行参数并完成工业验证。测试结果表明,开发的CEU型吸收剂CO_(2)脱除率达90%,最优再生热耗达2.42 GJ/t CO_(2),在工业装置上完成了>700 h稳定运行。

旋转爆轰发动机内煤粉-氢气两相爆轰流场数值研究

旋转爆轰发动机因其较高的热循环效率在航空航天领域备受关注。为了研究气固混合燃料在空气氛围中的旋转爆轰特性,在圆柱坐标系中建立了气固混合相燃料爆轰理论模型,并基于三维守恒元与求解元方法,对圆盘形燃烧室内的爆轰过程进行三维数值模拟。计算获得了气固混合相旋转爆轰波稳定传播时的流场结构,分析了爆轰流场的热力学参数分布特征、化学反应区分布以及旋转爆轰波后的波系分布特点。研究结果表明,微米级煤粉在氢气辅助作用下可快速反应并支持旋转爆轰波的稳定传播,但因盘形燃烧室的扁平结构特征和非预混喷注方式,导致爆轰波波阵面呈现为不规则的曲面。煤粉和氢气射流穿透空气层的能力差异导致气固混合燃料的化学反应区发生分离,最终以双反应区的爆轰组织形式支持旋转爆轰波稳定传播。旋转爆轰波不规则的曲面结构使其在扁平的燃烧室中发生多次反射,进而在爆轰波后有规律地出现多道反射激波。

容弹内片状无烟煤粉喷射掺混特性实验研究

粉末在容弹以及发动机燃烧室内的掺混状态对粉末爆轰特性有较大的影响,因此亟须对粉末在有限空间内的喷射掺混特性展开研究。搭建了一套透明的容弹系统,通过高速摄影监测系统,对片状煤粉在容弹内的喷射掺混过程进行观测,并对高速摄影拍摄图片进行后处理,分析煤粉在容弹内的喷射掺混变化规律。针对煤粉喷射掺混图像建立了一种灰度值标准差曲率分析方法,研究发现标准差曲率趋于0的初始时刻为煤粉掺混均匀最佳时刻,可以选取为最佳点火时间点,且该方法所选取的时刻与逐帧分析高速摄影图像所选取的时刻吻合。在煤粉浓度为120 g/m^(3),210 g/m^(3),300 g/m^(3)下,依次展开煤粉喷射掺混实验,并应用此灰度图像标准差曲率分析方法进行分析。实验结果表明:保持煤粉浓度一致时,掺混均匀性最佳时间随喷粉时长的增长而逐渐缩短,点火时刻提前;保持喷粉时长一致时,掺混均匀性最佳时间随供粉浓度的增长而延长,点火时刻延后。

淖毛湖煤和棉秆共热解协同效应分析

煤和生物质共热解过程中,填料方式会显著影响挥发分之间相互作用及产物分布。分析分隔放置(Case 1)、机械混合(Case 2)、煤在棉秆上层(Case 3)和煤在棉秆下层(Case 4)4种填料方式下淖毛湖煤(NMH)和棉秆(CS)共热解产物的分布、组成及性质,并结合分形理论研究共热解半焦的孔隙特征,探究共热解协同效应。结果表明,NMH和CS协同作用因填料方式不同而变化,填料方式对共热解产物分布及性质影响大。用Case 4方式时,共热解焦油产率最高,为15.94%,较理论计算值增加3.89%,正协同效应最显著。此时,CS热解产生的富氢组分及时与NMH热解挥发物发生交互作用,导致H_(2)、CH_(4)和C_(2)~C_(4)产量较理论值降低,共热解焦油产率增加。不同填料方式对共热解焦油中轻油馏分均产生负协同作用。含氧化合物相对含量减少可能是因为共热解过程促进脱氧反应(如脱羧和脱羰基化等),进一步生成脂肪烃,减少含氧官能团发生交联反应;在共热解中,·H自由基与活性含氧基团产生正协同作用,促使焦油中O、N、S原子向固体或气体产物转移。由半焦分形结果可知半焦分形维数D_(1)和D_(2)均在2~3间,说明半焦粗糙度和孔结构均满足分形结构基本特征。对于Case 3和Case 4方式,位于下层样品半焦的表面更粗糙。用Case 3方式所得CS-C孔隙更小;而Case 4方式所得NMH-C孔隙更不均匀,孔结构更复杂。

十二醇对黑龙关难浮煤泥浮选的强化作用研究

为提高难浮煤泥的精煤回收率,以黑龙关煤泥为研究对象,选用正癸醇、十二醇、十四醇三种长链脂肪醇,采用直接添加和与煤油复配的方式,进行了浮选试验。借助接触角、XPS、润湿热,分析了长链脂肪醇的作用机理。结果表明,无论是单独添加还是配制成复合捕收剂,十二醇的浮选效果最好,复配可以节省药剂用量。在捕收剂用量2 kg/t时,与煤油相比,15%比例复配药剂可将精煤产率提高23.89%,尾煤灰分提高9.53%,可燃体回收率提高28.23%。此外,十二醇处理过的煤泥接触角增加12.44°,润湿热降低5.37 J/g,亲水基团O—C=O含量降低3.25%。十二醇通过降低煤粒亲水性官能团含量,提高煤粒表面疏水性,十二醇复配药剂通过十二醇极性成分和煤油非极性成分的协同作用增大煤表面疏水面积提高浮选效果。

混煤镜质体反射率测定的影响因素及类型判别探讨

商品煤混煤是炼焦配煤过程中不同煤阶煤种混合而成的煤炭产品,其镜质体反射率的准确测定对混煤原始煤种的鉴别、焦炭质量预测及优化配煤技术均至关重要。结合我国现行煤岩检测标准中镜质体反射率测定概况,探讨煤岩样品制备、测定点数等因素对混煤镜质体反射率测定的影响。基于目前混煤反射率测定和类型判定过程中出现的现象,提出粉煤光片磨抛质量对组分鉴别和测定结果影响较大,测定点数对反射率分布统计直方图和混煤类型判定起决定作用。反射率测值标准差是判断混煤的关键指标,混煤类型判定主要依据测值标准差和凹口数,测值平均值对工业应用不具实际意义,反射率分布图的优势体现在可以直观地反映混煤的原始煤种及其混合程度。混煤镜质体反射率测定结果的准确性评价可通过反射率分布图进行定性判定,准确测定混煤镜质体反射率需要煤质检测人员具有足够的煤岩学相关知识,建议将煤岩学基础理论纳入煤检人员的技能培训体系,从而提升混煤镜质体反射率的测试准确度及降低混煤类型的判别误差。