热重法研究K2CO3与Fe2O3对煤粉燃烧反应性的影响

利用综合热重分析仪分别研究了K₂CO₃、Fe₂O₃对褐煤、烟煤、无烟煤、石墨等不同燃料的催化燃烧反应性的影响。结果表明,催化剂种类、添加量、粒径和燃料的变质程度对催化燃烧具有一定的影响;向无烟煤中加入K₂CO₃、Fe₂O₃两种催化剂,无烟煤的燃点由458℃分别降为319℃、405℃,燃烧速率由11.94%/min分别提高到26.40%/min、17.66%/min。K₂CO₃、Fe₂O₃对褐煤和烟煤的燃点没有明显的降低作用,但是对无烟煤和石墨燃点有明显的降低作用,且随着煤变质程度的增加,燃点降低幅度增大。由于引起燃点和燃速变化的原因不同,所以加入催化剂后造成燃点和燃速的变化也不同。     

煤的组成结构

煤是古代植物埋藏在地下,经历了复杂的生物化学和物理化学变化而形成的固体燃料。按不同的煤化阶段分为泥炭、褐煤、次烟煤、烟煤和无烟煤等。     

煤质特性对CeO_2催化煤粉燃烧的影响

利用酸洗法和燃烧法分别得到煤中的有机物(脱灰煤粉)和煤灰,研究了煤变质程度、显微组分、煤灰含量等煤质特性对CeO2催化煤粉燃烧的影响。研究发现,变质程度对CeO2催化煤粉燃烧具有明显的影响,变质程度越高的脱灰煤粉燃点降低越多,燃速提高越快。其催化燃烧顺序为褐煤烟煤无烟煤。同时研究发现,CeO2对神华烟煤两种主要显微组分的燃烧没有明显的催化作用。煤灰对脱灰煤粉燃烧也有催化作用,对人工煤而言,当煤灰含量低于18%时,煤灰与CeO2具有协同作用。煤灰的质量分数为6%时,煤灰与CeO2的协同作用最强,之后随着煤灰增加协同作用逐渐变弱;当煤灰的质量分数超过18%时,协同作用消失,CeO2的催化作用消失。说明煤灰含量超过18%时,CeO2的催化作用被抑制。     

工业、生活污泥与煤混合燃烧的灰熔特性研究

针对煤粉锅炉掺烧污泥后污泥对混合燃料灰熔特性的影响行为,利用矿物三元相图、XRD等分析手段,研究了不同特性污泥(生活污泥、工业污泥)与煤掺混燃烧过程中不同矿物组分的相互作用机制及灰渣的灰熔融特性变化特征。结果表明,三元相图能够有效预测煤和污泥掺混后灰熔融温度的变化趋势;低含量的氧化铁形成低温共熔体以及透辉石、钙长石会降低煤和污泥混合后的灰熔融温度;而钙镁橄榄石、莫来石和单体形式存在的氧化铁能提高煤和污泥混合后的灰熔融温度。工业污泥中的高硫组分在混烧过程中易形成硫酸盐的低温共融体。生活污泥中磷对灰熔点的影响与氧化铝及碱金属的比例有关,当氧化铝的含量占主要成分时,磷的存在趋向于降低灰熔点,而当碱金属占主要成分时,磷的存在趋向于提高灰熔点。     

重油残渣与不同煤阶煤共热解/气化实验研究

采用快速热解固定床在恒温热解条件下研究了不同混合比例不同煤阶煤与重油残渣共热解焦的形貌和焦产率的规律,进而在热重分析仪上采用非等温气化方法研究了煤焦、重油残渣焦及混合焦的气化反应性。结果表明,煤与重油残渣共热解焦有明显的结块现象,但焦产率与理论值一致,表明共热解过程中两者没有相互作用。重油残渣焦的气化反应性较褐煤和烟煤的低,比无烟煤活性略高,重油残渣与褐煤和烟煤混合焦气化反应速率比计算值高,表明气化过程有促进作用存在,进一步分析表明,煤中的矿物质如Ca、Fe,对重油残渣气化有一定的催化作用。     

煤质特性对CeO2催化煤粉燃烧的影响

利用酸洗法和燃烧法分别得到煤中的有机物（脱灰煤粉）和煤灰,研究了煤变质程度、显微组分、煤灰含量等煤质特性对CeO₂催化煤粉燃烧的影响。研究发现,变质程度对CeO₂催化煤粉燃烧具有明显的影响,变质程度越高的脱灰煤粉燃点降低越多,燃速提高越快。其催化燃烧顺序为褐煤<烟煤<无烟煤。同时研究发现,CeO₂对神华烟煤两种主要显微组分的燃烧没有明显的催化作用。煤灰对脱灰煤粉燃烧也有催化作用,对人工煤而言,当煤灰含量低于18%时,煤灰与CeO₂具有协同作用。煤灰的质量分数为6%时,煤灰与CeO₂的协同作用最强,之后随着煤灰增加协同作用逐渐变弱;当煤灰的质量分数超过18%时,协同作用消失,CeO₂的催化作用消失。说明煤灰含量超过18%时,CeO₂的催化作用被抑制。     

污泥水煤浆燃烧和污染排放特性研究

在3.2 MW 卧式炉中对污泥水煤浆和大同烟煤水煤浆进行了对比燃烧实验,分别研究了煤浆的着火、燃烧、结渣及污染物排放特性。结果表明,掺混 10%污泥的水煤浆着火容易,燃烧稳定,炉膛火焰分布均匀,燃烧和结渣特性均优于大同烟煤水煤浆。污泥的添加使水煤浆燃烧烟气中SO₂和NO_x的浓度偏高,实际应用中可通过加入固硫剂等方式缓解。污泥水煤浆在卧式炉中的燃烧状况较理想,为城市污泥资源化利用提供了一条可行的新途径。     

Combustion of sludge coal water slurry and emission property of contaminants

在3.2MW卧式炉中对污泥水煤浆和大同烟煤水煤浆进行了对比燃烧实验,分别研究了煤浆的着火、燃烧、结渣及污染物排放特性.结果表明,掺混10％污泥的水煤浆着火容易,燃烧稳定,炉膛火焰分布均匀,燃烧和结渣特性均优于大同烟煤水煤浆.污泥的添加使水煤浆燃烧烟气中SO2和NOx的浓度偏高,实际应用中可通过加入固硫剂等方式缓解.污泥水煤浆在卧式炉中的燃烧状况较理想,为城市污泥资源化利用提供了一条可行的新途径.     

用EDTA容量法间接测定煤中的硫铁矿硫

用硝酸氧化烟煤或无烟煤中的硫铁矿时,除了能把硫氧化成硫酸根离子外,还有部分硫以元素状态析出。例如用硫酸钡直接重量法测定烟煤或无烟煤中的硫铁矿硫时,其测值容易偏低。用硝酸氧化褐煤中的硫铁矿时,褐煤侧链中的部分有机硫也被氧化成硫酸盐。若用硫酸钡直接重量法测定褐煤中的硫铁矿硫,其测值容易偏高。用间接容量法测定虽可避免上述缺点,但目前无论是用重铬酸钾法、硝酸亚汞法或碘量法,都需在硝酸浸取液中加入氢氧化铵将铁沉淀,经过滤、洗涤、然后加酸使氢氧化铁溶解,再用标准溶液进行滴定,换算为煤中硫铁矿硫的含量,操作费时。本文直接在硝酸浸取液中,以磺基水杨酸为指示剂,用EDTA标准溶液滴定铁,此法对煤中硫铁矿硫的测定结果有     

褐煤水热提质改善水煤浆的成浆性、流变性和稳定性的实验研究

采用水热法对小龙潭褐煤进行提质处理,从煤质特性、含氧基团、表面亲水性和粒度分布等因素,探究了水热提质对褐煤水煤浆成浆浓度、流变特性以及稳定性的影响。结果表明,水热提质脱除了褐煤中的水分,氧含量降低,煤阶升高。水热提质脱除了褐煤中含氧基团,煤水表面接触角增大,褐煤表面亲水性得到改善。小龙潭褐煤颗粒粒度呈现双峰分布,水热提质后褐煤颗粒粒径减小且趋于规则。水热提质改善了水煤浆的成浆性能,成浆浓度由提质前的44.09%,最高可提升到61.94%。在相近的表观黏度下,水热提质后水煤浆的稠度系数K减小,流变指数n增大,水热提质在降低浆体黏度的同时,仍保持假塑性流体特征。水热提质降低水煤浆的析水率,延缓了浆体出现硬沉淀的时间,改善浆体的稳定性。水热提质从理化特性对褐煤进行深度改性,从而获得高浓度,假塑性以及稳定性良好的符合工业应用的水煤浆。     

Devolatilisation characteristics of coal and biomass blends

The characterisation of the initial devolatilisation products could provide important information for understanding synergistic effects and subsequently the formation routes leading to toxic organic compounds and soot during co-combustion. Initial devolatilisation characteristics of the fuels have been characterised following co-pyrolysis experiments. This paper investigates the devolatilisation behaviour during co-pyrolysis of pinewood together with one of three coals of different rank, lignite or high-volatile bituminous of different origin. A range of pyrolysis experiments has been performed over a temperature range from 400 to 900 °C using pyrolysis–GC–MS (py–GC–MS) and thermogravimetric analysis (TGA). Larger scale batch pyrolysis experiments of the hv bituminous coal–pine mixture have been performed enabling collection of the evolved tars. These tars have then been characterised by GC–MS and size exclusion chromatography (SEC). For these batch pyrolysis tests, synergy (non-additive behaviour) was observed and the blend pyrolysis oil contained a decrease in aromatics and an increase in phenols than would be expected for additive behaviour. The molecular weight distributions of the evolved tars also show non-additive behaviour. For the TGA experiments, additive behaviour was seen for all the coal–pine blends studied. Similarly, no obvious synergy was observed by py–GC–MS for the bituminous coal–pine blends, or for model compound–coal and coal–biomass component blends. Non-additive combustion behaviour is not easily explained by studying devolatilisation because of the difficulty in replicating the conditions of temperature profile and residence time experienced by the volatiles. Thus, conflicting behaviour is exhibited depending upon pyrolysis technique.     

煤液化残渣与褐煤混煤燃烧特性的实验研究

煤液化是提高煤炭资源利用率、减轻燃煤污染的有效途径[1].在煤液化工艺过程中,煤液化残渣的主体是由液化原料煤中未转化的煤有机体、无机矿物质以及外加的液化催化剂组成,是一种高炭、高灰和高硫的物质,在某些工艺中会占到液化原煤总量的30%左右,如此多的残渣量对液化过程的热效率和经济性所产生的影响是不可低估的[2].     

Thermochemical and Toxic Element Behavior during Co-Combustion of Coal and Municipal Sludge

The thermochemical and kinetic behavior of co-combustion of coal, municipal sludge (MS) and their blends at different ratios were investigated by thermogravimetric analysis. Simulation experiments were performed in a vacuum tube furnace to determine the conversion behavior of toxic elements. The results show that the combustion processes of the blends of coal and municipal sludge are divided into three stages and the combustion curves of the blends are located between those of individual coal and municipal sludge samples. The DTG_max of the sample with 10% sludge addition reaches a maximum at the heating rate of 20 °C/min, indicating that the combustion characteristics of coal can be improved during co-combustion. Strong interactions were observed between coal and municipal sludge during the co-combustion. The volatilization rates of toxic elements decrease with an increasing proportion of sludge in the blends during co-combustion, which indicates that the co-combustion of coal and sludge can effectively reduce the volatilization rate of toxic elements. The study reflects the potential of municipal sludge as a blended fuel and the environmental effects of co-combustion of coal and municipal sludge.     

Experimental study on interaction and kinetic characteristics during combustion of blended coals

The combustion behaviors and kinetic parameters of three parent coals (A1, A2, and A3) and their blends (A1/A2 and A2/A3) have been evaluated under oxidizing atmosphere (O₂ and N₂ mixtures), using a non-isothermal thermo-gravimetric analyzer. The aim of this study is to investigate the interaction between the blended components during the process of co-combustion, and the effects of blending ratio and oxygen concentration (10, 15, and 21%) on combustion performance of blended coals. When high reactivity and low reactivity coals are co-combusted, double peaks are observed in the DTG curves, and significant interaction occurs in the temperature range between the two peaks (T _p1 and T _p2). The activation energies obtained by Coats–Redfern method indicate that the activation energies of blended coals are lower than that of parent coals. The combustibility index S is used to evaluate the combustion performance of blended coals, and the results show the non-additive effects of the combustion characteristics of blended coals. The increased oxygen concentration results in a significant improvement of combustion performance of blended coals. In addition, as the blending ratio of high reactivity coal is increased, the oxygen can greatly enhance the combustion stability of blended coals.     

A TG/DTA study on the effect of coal blending on ignition behaviour

Understanding the ignition behaviour of coal is of utmost importance for the design of boilers and control of the combustion process. In recent years there has been an increasing utilisation of coal blends for combustion, but information on the possible interactive effects during ignition of the individual components is scarce. In this work the ignition behaviour of a series of coal blends, made up from three coals of different rank, sub-bituminous, high volatile and low volatile bituminous, was studied. To this end a thermogravimetric analyser linked to a mass spectrometer for evolved gas analysis was used. Different ignition behaviour was observed for the coals studied; the sub-bituminous and low volatile bituminous coals ignited heterogeneously, while homogeneous ignition occurred for the high volatile bituminous coal. In the case of blends of the low and high volatile bituminous coals, different mechanisms of ignition were observed depending on the blends composition. This revised version was published online in July 2006 with corrections to the Cover Date.     

Thermal characteristics of the combustion process of biomass and sewage sludge

The combustion of two kinds of biomass and sewage sludge was studied. The biomass fuels were wood biomass (pellets) and agriculture biomass (oat). The sewage sludge came from waste water treatment plant. The biomass and sludge percentage in blends with coal were 10 %. The studied materials were characterised in terms of their proximate and ultimate analysis and calorific value. The composition of the ash of the studied fuels was also carried out. The behaviour of studied fuels was investigated by thermogravimetric analysis (TG, DTG and DTA). The samples were heated from an ambient temperature up to 1,000 °C at a constant three rates: 10, 40 and 100 °C min^?1 in 40 mL min^?1 air flow. TG, DTG and DTA analysis showed differences between coal, biomass fuels and sewage sludge. 10 % addition of studied fuels to the mixture with coal changed its combustion profile in the case of sewage sludge addition. The combustion characteristics of fuel mixtures showed, respectively, qualitative summarise behaviour based on single fuels. Evolved gaseous products from the decomposition of studied samples were identified. This study showed that thermogravimetric analysis connected with mass spectrometry is useful techniques to investigate the combustion and co-combustion of biomass fuels, and sewage sludge, together with coal. Non-isothermal kinetic analysis was used to evaluate the Arrhenius activation energy and the pre-exponential factor. The kinetic parameters were calculated using Kissinger–Akahira–Sunose model.     

钾对秸秆混煤燃烧特性影响的研究

选用经酸洗法脱灰的煤和秸秆制得实验样品。采用TG/DTG/DTA技术研究了不同秸秆含量下碱金属钾对秸秆与煤混合燃烧特性的影响。研究结果表明,KOH促进脱灰煤和脱灰混合样品的着火燃烧,使其最大燃烧速率温度及燃尽温度降低,但提高了脱灰秸秆的着火温度。秸秆混煤燃烧反应符合一级反应模型,KOH的添加对混煤燃烧具有催化作用,使混合燃烧反应活化能降低10kJ/mol。     

稻草与煤固定床共热解特性的研究

选取稻草为生物质原料,将其与两种不同煤阶的煤(内蒙褐煤和神府烟煤)分别以0∶100、20∶80、40∶60、60∶40、80∶20、100∶0的干基质量比均匀混合.借助固定床反应器,研究了稻草与两种煤的共热解特性,探讨了共热解过程中可能存在的协同作用.结果表明,稻草添加有利于共热解气体产物的生成,且对神府煤作用更明显;稻草含量越高,热解气体产量的实验值与加权平均计算值的偏差也越大,说明稻草与煤共热解过程发生了协同作用.而共热解所得焦产量的实验值与加权平均计算值基本一致.热解焦傅里叶红外光谱分析结果表明,稻草添加对热解焦的官能团未造成显著影响.     

Thermogravimetric analysis of the co-combustion of the blends with high ash coal and waste tyres

Incineration methods are becoming increasingly important from the view point of the need to minimize the environmental impact of waste tyre disposal. Combustion of waste tyre, one high ash coal and tyre-coal blends with 10, 30 and 50% waste tyre were investigated by means of thermogravimetric analysis (TGA) carried out at 20 K min⁻¹ in the temperature range from ambient temperature to 1273 K. And effects of the mixed proportion between coal and waste tyre on the combustion process, ignition and burnout characteristics were also studied. The results indicate that the combustion of waste tyre is controlled by the emission of volatile matter, the regions are more complex for waste tyre (three or more peaks) than for coal (one peak). Also as compared with the case of burning only high ash coal, the incorporation of waste tyre can improve the combustion characteristics of high ash coal, especially the ignition performance and the peak weight loss compared with the separate burning of waste tyre and coal. Moreover, comparisons of the TG-DTG profiles between experimental and calculational results, it is indicate that there is a comparatively important difference, the co-combustion characteristics is the coupling effect between waste tyre and coal. The data resulting also showed that the co-combustion of waste tyre and low quanlitied coal as fuel is feasible.     

煤中有机硫形态结构和热解过程硫变迁特性的研究

利用热解 质谱并结合固定床热解反应装置，对煤中有机硫的形态主其对加氢热解过程 变迁特性的影响，进行了较系统的研究。结果表明，煤中有机硫的形态结构在褐煤中主要以脂肪族、芳香族硫化物为主，而在 煤中则主要以各种不同芳构化程度的噻吩结构为主，初步表明煤中有机硫形态结构随煤变质程度的变迁呈较强的连续递变性。煤热解过程中硫在呼产物中的变迁和分布与煤中有机硫的形态结构特点密切相关。较高芳构化噻吩结构不完全的氧