THE STUDY OF THE BASIC THEORY AND THE APPLICATION OF REMOVAL PYRITE AND ASH FROM FINE COAL WITH ELECTROSTATIC SEPARATOR

The effect of removing pyrite and ash ffom fine coal with electrostatic separator is determined by the electric property of coal, the distribution of corona ion and etectrostatic field, and the disperse and even feed. The dielectric constant of coal and mineral matter is studied in this paper and the amendment has been made to survey theory. The oscillogram is adopted to study the distribution of corona ion and electrostatic field.The paper details the study of remoing pyrite and ash from fine coal, and the test results demonstrate the high efficiency of removing pyrite and ash with electrostatic separator.

Flotation performance analysis on coal washery rejects

The coal washery rejects cause major environmental problems in various parts of the globe.Nearly 1 Mt of coal rejects discarded as waste,is accumulated per annum in India,during washing or cleaning of raw coal.Cleaning coal,especially washery rejects,has posed a major challenge to the recovery of fine coal.Froth flotation is a better choice for processing coal washery rejects.In this study,flotation studies are attempted on the coal slurry received from Sudamdih coal washery,Jharkhand,India.A statistical design package(Minitab V17)was used to study the effect of process variables like collector and frother dosages on the responses.Regression equations for froth height,froth density,recovery and ash content of clean coal were developed.The coefficient of correlation(R2)values between the experimental and the predicted values of the flotation responses was found to be greater than 0.98 for all the models.Clean coal product was analyzed for recovery,froth height,and ash content by varying pulp densities.Results show that the coal slurry sample could be evaluated with acceptable recovery via flotation.Clean coal with an ash content of 17.2%is obtained with a 70%recovery from 35.5%ash.The cleaned coal can be used in powder coal-consuming industries.

Experimental Research on Enhanced Cyclone Separation of Acoustic Agglomerated Particles

To test the particles solidity and to verify the separating efficiency at normal atmospheric temperature, the experimental research was made on the enhanced cyclone separation of acoustic agglomerated fly ash particles. The separating efficiency has increased by 3%-4% in a sound field with 150 dB pressure level compared with that obtained without acoustic wave processing. The enhanced cyclone separation test study for acoustic agglomerated particles has provided a technical basis for pressurized fluid bed combustion(PFBC) application.

Pre-combustion mercury removal with co-production of hydrogen via coal electrolysis

Pre-combustion mercury removal via coal electrolysis was performed and investigated on a bench-scale coal electrolytic cell(CEC)systemically,and factorial design was used to determine the effect of different operating conditions(coal particle size,operating temperature,operating cell voltage,and flow rate of slurry)on the percentage of mercury removal,percentage of ash removal,and dry heating value change.The results showed that the operating cell voltage,as well as the interaction between operating cell voltage and coal particle size,are significant factors in the percentage of mercury removal.There is no significant factor in the percentage of ash removal and the dry heating value change,but the coal could be purified while keeping the dry heating value almost constant after electrolysis.A co-product of hydrogen could be produced during coal electrolysis with 50%lower energy consumption compared with water electrolysis.Meanwhile,a mechanism for mercury removal in coal was proposed.The facts indicate that coal electrolysis is a promising method for precombustion mercury removal.

Frequency comparative study of coal-fired fly ash acoustic agglomeration

Particulate pollution is main kind of atmospheric pollution.The fine particles are seriously harmful to human health and environment.Acoustic agglomeration is considered as a promising pretreatment technology for fine particle agglomeration.The mechanisms of acoustic agglomeration are very complex and the agglomeration efficiency is affected by many factors.The most important and controversial factor is frequency.Comparative studies between high-frequency and low-frequency sound source to agglomerate coal- fired fly ash were carried out to investigate the influence of frequency on agglomeration efficiency.Acoustic agglomeration theoretical analysis,experimental particle size distributions （PSDs） and orthogonal design were examined.The results showed that the 20 kHz high-frequency sound source was not suitable to agglomerate coal-fired fly ash.Only within the size ranging from 0.2 to 0.25 μm the particles agglomerated to adhere together,and the agglomerated particles were smaller than 2.5 μm.The application of low-frequency （1000–1800 Hz） sound source was proved as an advisable pretreatment with the highest agglomeration efficiency of 75.3%,and all the number concentrations within the measuring range decreased.Orthogonal design L16 （4） 3 was introduced to determine the optimum frequency and optimize acoustic agglomeration condition.According to the results of orthogonal analysis,frequency was the dominant factor of coal-fired fly ash acoustic agglomeration and the optimum frequency was 1400 Hz.

超声空化-流体剪切协同强化油团聚分选煤气化细渣

煤气化细渣(CGFS)具有较高的利用价值,但残炭回收率低极大地制约了其资源化利用。油团聚分选法在CGFS分选过程中具有明显优势,但炭灰共生结构严重限制了油团聚分选效率。为突破油团聚法分离富集残炭技术的瓶颈问题,考察了超声时间、超声功率、流体剪切时间及其交互作用对油团聚分选效果的影响,并结合BET、粒度分布、FT-IR、XPS以及SEM-EDS等分析手段,揭示了超声空化-流体剪切(UC-FS)协同预处理对油团聚分选效果的强化机理。结果表明:当超声功率为270 W、超声处理时间29 min、流体剪切时间23 min时,能分选得到灰分为9.55%的精矿、灰分为91.51%的尾矿,可燃体回收率可提高至90.54%。超声空化作用使原本致密的炭灰结构逐渐松散,与流体剪切的冲刷作用协同促进CGFS的孔隙结构的发展,使炭灰颗粒解离度增加,从而降低了精矿灰分。UC-FS协同预处理能够有效增加残炭表面C—C、C=C以及C—H等疏水基团的比例,使其接触角由110.34°增加到121.16°,扩大了炭和灰颗粒表面疏水性差异,提高了油团聚分选的效果。UC-FS协同预处理使炭灰颗粒高效分离的强化作用主要归因于超声空化气泡与细粒微球耦合产生的微磨料效应。可为实现CGFS分质资源化利用提供理论基础和技术指导。

化学团聚耦合低温省煤器强化除尘协同脱硫废水零排放试验研究

煤燃烧产生的细颗粒物和烟气脱硫产生的脱硫废水是燃煤电厂污染治理的难点。该文提出一种化学团聚耦合低温省煤器强化除尘协同脱硫废水零排放的处理工艺。将加入团聚剂的工艺水或脱硫废水通过双流体雾化喷入低温省煤器前烟道,细颗粒物在化学团聚剂液桥力的作用下发生团聚长大,沿程水分蒸发后,液桥力转化为固桥力形成大的团聚体,耦合低温省煤器促进静电除尘器对细颗粒物的脱除效率。示范试验结果表明,运行化学团聚可使粉尘排放浓度降低63.1%,168 h内平均粉尘排放浓度为2.66 mg/m^(3);基于运行数据优化了团聚剂喷量与低温省煤器循环水量;连续运行脱硫废水对强化除尘效果没有明显影响,实现了超低排放以及脱硫废水零排放。

新型除磷填料的制备及再生能力试验

以沸石、粉煤灰和煤气化渣为原材料,制备一种低成本、高效的新型除磷填料,对其吸附性能以及再生能力进行探究,并对填料吸附磷前后的微观形貌、元素组成以及晶体结构等变化进行分析。研究结果表明,填料主要组成为O、Si、Ca、Al、Fe、Mg,其中Ca元素质量分数最高;吸附后填料表面变得光滑平整,EDS和XRD分析表明Ca元素在吸附过程中发挥重要作用;在磷质量浓度为50 mg/L、吸附剂投加量为14 g/L的条件下,新型除磷填料对磷的去除率达到了80%,吸附性能相较于原材料明显提高;在pH=1和pH=13的条件下,填料对磷的释放率分别为142.39%和83.26%,酸性条件的解吸效果明显优于碱性条件,表明强酸/强碱有利于磷从填料中释放出来;再生能力实验研究显示,经过4次再生后,酸性再生后的填料对磷的去除率明显低于碱性再生;在实际应用中碱性再生1~2次时,填料对磷的去除率在60%以上,具有较高的再生回用可能性。

添加石灰石对准东煤CFB燃烧过程床料团聚和受热面积灰的影响

高钠准东煤在循环流化床(circulating fluidized bed,CFB)燃烧过程产生严重的床料团聚和受热面积灰现象。为探究高钙添加剂对积灰和团聚的影响,以石灰石为添加剂、以石英砂为床料,在小型CFB系统上进行准东煤的燃烧实验,并使用环境扫描电镜、X射线衍射仪和电感耦合等离子发射光谱仪分析床料和沉积灰的微观形貌、晶相矿物组分和Na/Ca含量,结合热力学计算软件FactSage 8.2,计算平衡态时产物的化学组成。结果表明:添加石灰石有利于床料表面形成富含Ca的高熔点包覆层,从而有效抑制低熔点Na/Ca硅酸盐的形成,减缓了床料团聚。与此同时,受热面外层积灰富含CaSO_(4)、CaO和Ca的硅酸盐等高熔点矿物,无明显烧结和熔融倾向。热力学计算表明,添加石灰石促进了高熔点Ca基矿物的形成,抑制了Na基矿物和液态熔渣的形成,是缓解准东煤CFB燃烧过程受热面积灰和床料团聚的主要原因。研究结果初步证实添加石灰石能够缓解CFB燃用准东煤过程的床料团聚和积灰问题,可为CFB大规模、高比例燃用高碱金属燃料提供一定理论指导。

基于化学团聚技术强化脱除细颗粒物的试验研究

燃煤机组经过超低排放改造后,除尘器对粉尘的脱除效率大大提升。然而,除尘器对PM_(2.5)等细颗粒的捕获能力有限,导致许多细颗粒通过烟囱排入大气,降低了周边空气质量。基于化学团聚技术,在国内某600 MW燃煤电站开展细颗粒物排放控制示范试验研究,旨在通过系统的采样测试探究化学团聚技术对PM_(2.5)排放的控制效果。基于固定污染源采样标准(ISO 23210-2009)开展现场采样测试。对化学团聚技术投运前后细颗粒物排放质量浓度进行检测,依托样品表征方法对颗粒样品进行测试分析,综合评价化学团聚技术对燃煤细颗粒排放的控制作用。结果表明:团聚吸附剂喷射后,静电除尘器(electrostatic precipitator,ESP)入口粉尘的平均粒径由57.3μm增大至69.6μm,平均粒径增大21.5%;团聚后,ESP入口PM_(1),PM_(2.5),PM_(10)质量浓度分别由124.2 mg/m^(3),359.5 mg/m^(3),947.7 mg/m^(3)减小至85.6 mg/m^(3),240.6 mg/m^(3),492.0 mg/m^(3),团聚效率分别为31.1%,33.1%,48.1%。飞灰粒径筛分结果表明:团聚后,粒径在38μm以下的飞灰质量分数由32.7%减小至9.2%,而粒径在38μm~75μm范围内的飞灰质量分数由29.7%增大至62.8%;最终,在团聚吸附剂作用下,湿法烟气脱硫(wet flue gas desul furization,WFGD)出口总粉尘质量浓度由1.32 mg/m^(3)降低至1.09 mg/m^(3)。综上,化学团聚技术对燃煤电站细颗粒物团聚效果显著,PM_(2.5)脱除效率显著提升。

巴基斯坦某燃煤电站工程除灰渣系统设计

该文介绍巴基斯坦某燃煤电站的工程条件,除灰渣系统的设计原则,详述除渣系统、除灰系统、灰库系统、气化风系统、压缩空气系统和石子煤系统的设计,给出各系统主要设备的参数和数量、除渣系统和除灰系统的工艺流程图,从设计标准、当地温度和湿度、灰渣综合利用、盐雾腐蚀、细渣处理和各单位配合的几个方面,总结本工程的设计经验。解决现场反馈的干灰散装机的适用性、干燥器前进口阀门的类型和空压机房排污水管道设计等问题,高质量地完成除灰渣系统的设计任务。

绿水洞煤矿选煤厂粗煤泥系统改造实践

绿水洞煤矿选煤厂由于缺少粗煤泥回收环节,导致1~0.25 mm部分粗煤泥直接回收作为中煤,造成粗精煤泥产品的损失,影响了选煤厂综合经济效益。结合现场实际及工艺分析,制定并实施了分级旋流器+FBS流化床分选机+叠层高频细筛+煤泥离心机的粗煤泥回收系统优化改造方案。改造实践表明,系统稳定运行,粗精煤泥灰分稳定控制在10%~10.5%范围内,粗精煤泥产量5.88万t/a,有效减少了精煤损失,为选煤厂提质增效发挥了积极作用。

水溶液隔膜电解除铁

在用高铝粉煤灰盐酸法制备氧化铝的过程中,粉煤灰中的铁会随酸性浸出液进入氯化铝溶液.为了低成本降低氯化铝溶液中铁杂质的质量分数,提出了在水溶液中电解除铁的方法.除铁实验中使用双室隔膜电解槽,对初始条件为pH值2.0,Fe^(2+)质量分数0.25%的FeCl_(2)溶液进行循环电解,研究了几种常见金属阴极板上单质铁的析出效果.结果表明:使用钛、铁、锡、铜、铅5种金属电极均可在5 h电解后达到90%的除铁率,溶液中亚铁离子的质量分数降低至小于0.03%.

化学团聚强化除尘系统协同脱硫废水零排放改造分析

针对燃煤电厂的340 MW燃煤机组的化学团聚强化除尘系统的运行进行了分析,提出化学团聚强化除尘系统协同脱硫废液零排放的改造方案,以提升强化细飞灰颗粒脱除效率和脱硫废液零排放的需求,在燃煤机组的节能减排方面具有重大应用价值。

高炉喷吹焦炭除尘灰的研究与实践

为解决焦炭除尘灰带来的环境污染和难以高效低碳处理问题,结合其理化特性,设计了高炉喷煤配加不同比例焦炭除尘灰的性能对比实验,稳定烟煤比例45%,用焦炭除尘灰替换不同比例无烟煤的方式,研究了焦炭除尘灰对混合煤粉性能的影响。结果表明,焦炭除尘灰配加比例3%时,混合煤粉燃烧性能指数相对最佳;配加比例5%时,混合煤粉燃烧速率相对最佳;配加比例8%时,混合煤粉可磨性指数和灰熔点相对最佳。通过进一步开展工业试验,研究高炉喷煤配加不同比例焦炭除尘灰的冶炼参数与成本变化,明确高炉喷煤中配加焦炭除尘灰的效益最优配加比例为5%。通过高炉喷吹焦炭除尘灰的方式,不仅可以充分发挥焦炭除尘灰的价格优势,降低高炉燃料成本7.80元/t,而且可以有效解决焦炭除尘灰在储存、运输过程中衍生出的一系列环保问题,实现了焦化环节固废零排放,铁前工序单位产能,降低二氧化碳排放40.82 kg/年,取得了焦炭除尘灰高效低碳处理的效果。

化学团聚促进燃煤细颗粒物脱除的试验研究

采用燃煤热态试验系统,进行了分别在电除尘器和脱硫塔入口烟气、脱硫液中添加化学团聚剂促进电除尘、湿法烟气脱硫系统脱除细颗粒物的试验研究;试验考察了团聚剂添加前后细颗粒物浓度及其粒度分布的变化,以及团聚剂类型、浓度、添加点烟温等对细颗粒物脱除效果的影响。结果表明:化学团聚技术可使细颗粒物平均粒径增大约4倍,数浓度降低40%以上;在电除尘器和脱硫塔入口烟气、脱硫液中添加化学团聚剂均可有效提高细颗粒物的脱除效果,其中在烟气中添加团聚剂的作用效果与添加点处烟温存在密切关系,高温烟气(250℃)中试验采用的有机团聚剂容易失效,而无机团聚剂仍能维持相同效果。

燃煤飞灰低频下声波团聚的实验研究

通过实验研究了低频下燃煤飞灰的声波团聚。燃煤飞灰气溶胶在声波作用下粒径分布发生明显变化,大量细颗粒团聚产生粗颗粒,气溶胶浓度降低。在147dB、1400Hz时,气溶胶总浓度和PM2.5浓度分别减少了68.4%和75.6%,达到很好的团聚效果。从扫描电镜照片中可以观察到声波团聚过程中产生了粒径大于10μm的链状团聚体。在声波作用下,气溶胶总浓度随团聚时间呈指数衰减规律降低。实验证明了声波团聚中存在最佳频率,在此频率下团聚效果最好,偏离该值团聚效果急剧降低。另外,实验发现最佳频率随声压级的增大而轻微降低。同时,研究了声压级、停留时间和气溶胶初始浓度等参数对声波团聚的影响。

加压灰熔聚流化床粉煤气化技术的研究与开发

建立了一套直径０．２ ｍ ，压力１．５ ＭＰａ， 日处理量３ ｔ～４ ｔ煤的加压灰熔聚流化床粉煤气化试验装置， 在该装置上进行了府谷煤的气化试验． 考察了压力、温度对煤处理量、碳转化率、排灰碳含量、煤气组成等工艺指标的影响， 确定了加压下开工、运行、停车程序． 试验运行验证了工艺的可行性、安全可靠性和设备设计的合理性．

火力发电厂燃煤飞灰润湿性能

Chemical agglomeration is one of the most effective methods to remove fine particles from coal fired power plants.The wetting of particles by agglomeration agent droplets plays an important role in the chemical agglomeration processes.The effect of wetter concentration and temperature on the wettability of the fly ash from Xiaolongtan power plant in three different wetting agents [sodium dodecyl sulfate(SDS),sodium dodecyl benzene sulfonate(SDBS) and Triton X 100(TX100)] was investigated.Laser particle size analyzer was used to determine the wettability of the fly ash.The results showed that only PM+10 was completely wetted by water,but PM+2.5 was wetted completely by 0.25% SDS solution,and PM+1 was wetted completely by both 1% SDS and 0.4%SDBS solutions under the experimental conditions.It was effective to wet the fly ash particles by dilute TX100 solution.With increasing temperature of wetter from 20℃ to 60℃,solution surface tension decreased and better wettability of the fly ash exhibited.Owing to the good performance of wetting agents investigated,this study identified some potential components for the synthesis of chemical agglomeration agents.

不同化学预处理对神府煤粉孔隙结构特征的影响

为给制备煤基纳米复合材料提供参考,对利用酸脱灰、碱脱腐植酸、空气氧化3种化学预处理方法制备的神府脱灰煤样、脱灰脱腐植酸煤样和脱灰氧化煤样,采用低温液氮吸附试验对各煤样的孔隙结构特征进行了研究。结果表明:酸脱灰、碱脱腐植酸、空气氧化处理对煤粉的孔径分布有明显影响,化学预处理后煤粉的总孔容和比表面积均减小,平均孔径增大,各孔径段孔隙数量减少,其中微孔数量减少最为明显。化学预处理过程对煤样的孔隙类型影响较小,原煤样和预处理煤样均以一端封闭的不透气性孔为主。神府煤粉经过以上3种化学方法处理后,其比表面积和孔体积分形维数均减小,孔隙结构特征得以改善,煤粉孔隙系统复杂程度降低,更适合作为制备煤基功能复合材料的基体。