成灰温度对污泥灰矿物质演变及热力学特性的影响研究

采用STA、SEM、XRD等谱学表征技术对不同成灰温度下的污泥灰样进行理化特性分析。研究表明,低温灰样仍含有呈黑棕色的残余未燃尽物,矿物质成分以方解石、石英以及焦磷酸盐为主,随着成灰温度升高,灰样中的未燃尽物燃烧分解而逐渐变为铁红色,并形成较多晶枝结构,直至熔融,同时矿物质成分变化显著,主要以中长石类、硬石膏、赤铁矿以及磷酸正盐为主。同步热分析实验表明,随着受热温度升高,不同成灰温度下的灰样均出现了吸附水、结晶水析出,污泥灰残余有机物燃烧分解,白云石、方解石和白云母分解,以及随后的硬石膏分解等失重阶段,而且成灰温度越低,终止失重质量越大。由于低温灰样保留了较多的污泥原有特征,因此吸热量大于高温灰样。     

城市污泥灰分矿物质组分演变与热重实验分析

运用XRD、EDX以及TGA等实验方法对大连不同污水处理厂不同灰化温度下的污泥灰分进行分析。研究表明,在实验温度范围内,灰分中矿物质组分变化较大,温度较低时灰分中矿物质以方解石、石英以及焦磷酸盐为主,另外存在硅线石、磁铁矿和赤铁矿等。随灰化温度的升高,除石英稳定外,灰分中长石类、硬石膏以及磷酸正盐和磷酸铝钙、磷酸铁钙成为主要成分。由于灰分中碱性氧化物较多,温度超过900℃出现了部分熔融现象。TGA实验表明,同一种物质不同温度的灰分失重明显不同,灰化温度越高,失重越小。不同灰化温度下灰分反映出污泥在焚烧过程中反应进程,随受热温度升高,都出现了矿物质失去吸附水,矿物质析出结晶水,污泥中有机物燃烧,方解石分解,以及随后的硬石膏分解等失重阶段。     

杜仲药渣与煤的混烧特性及灰熔融特性研究

本文采用热重分析仪分析了杜仲药渣和石下江煤的混合样品的燃烧特性,采用灰熔点测试仪、X射线荧光仪、X射线衍射仪及扫描电子显微镜对混合物灰样的灰熔融特性变化进行了分析.结果表明:药渣掺混比为40%时着火温度最低;加入90%药渣时,稳燃性指数、综合燃烧特性指数、最大燃烧速率和平均燃烧速率值均达到最大,燃尽温度最小;在杜仲叶渣和煤的共燃过程中,发生了协同作用,生成了一些新的矿物质,混合灰样的灰熔融温度随着药渣质量分数的增多而减小.     

污泥和脱灰污泥的热解特性及NOx前驱物的转化研究

利用热重-质谱联用技术(TG-MS)研究污泥及脱灰污泥热解特性及NH_3等含NOx前驱物释放规律,结果表明:污泥脱灰后,样品热解起始温度、NH_3、HCN、HNCO、CH_3CN等NOx前驱物析出温度均升高。同时,在750～900℃均并未出现明显失重,热解过程总失重率远远高于原污泥。由于脱灰污泥所含矿物质已被大部分脱除,不再留存于污泥及焦炭中,N_2在610℃后的高温段并未见析出。除此之外,HCN、HNCO、CH_3CN、H_2等气体均在高温段升高。     

恒温下准东煤粉燃烧特性研究

针对准东煤碱金属含量高导致灰熔融温度低、在燃烧过程中容易造成沾污及结焦等问题,利用恒温热重实验系统,研究了准东煤的燃烧特性及温度、煤种掺混等对燃烧特性的影响。实验结果表明：单煤煤种燃烧过程中,不同煤种燃尽时间、燃烧速率存在显著差异,其中路茂通坎乡煤种和永华金泰煤种差异最大,路茂通坎乡煤种易着火,燃烧速率快,燃尽时间短;随着温度升高,单煤燃烧失重曲线发生左移,燃尽时间缩短,燃烧速率上升,表明温度升高会加速煤粉燃烧,并且1 000℃后提高温度对焦碳燃尽的促进作用更明显;掺混燃烧过程中,掺烧高挥发分的煤种可以有效改善煤粉燃烧初期着火特性,而掺烧高固定碳煤种可使燃尽时间延长,从而降低燃尽率;混煤掺烧能够提高灰熔点,有效改善准东煤熔融特性,从而在煤源方面减少或者避免炉膛受热面沾污、结渣,确保锅炉运行的安全性和经济性。     

新疆棉杆直燃特性分析

为实现新疆棉杆的生物质能合理利用,以新疆乌苏市皇宫镇的棉杆为典型样本,进行生物质燃烧特性研究。对棉杆样品进行了工业分析和热重分析,对其燃烧产物-灰样进行熔融烧结实验和汞含量分析。利用X射线荧光光谱仪对完全燃烧温度分别为400、600、800℃的灰样的微量元素成分进行分析,并对灰样中重金属汞含量进行测定。研究发现:棉杆的燃烧过程经历了2个失重峰值,当燃烧温度到达800℃时,棉杆的失重率几乎为零;灰样中K元素含量随温度升高而减少;Cl元素含量在燃烧温度为400和600℃时基本一致,当燃烧温度升高到800℃时,Cl几乎全部析出,灰样中的其它元素含量基本没有变化。400℃灰样中金属元素主要以碳酸盐、硅酸盐和氯化物的形式存在;600℃时灰样中形成的化合物较为复杂;800℃灰样中金属元素主要以氧化物的形式存在。棉杆中的汞含量远低于现有电站的燃煤含量,其燃烧的固体产物灰中的汞含量也比煤灰少。     

煤显微组分富集物燃烧特性滴管炉试验研究

利用滴管炉对不同显微组分富集样进行了燃烧试验，利用灰示踪法对它们的燃烧特性进行了分析。结果显示，不同显微组分组成样的燃烧特性不同，富惰质组样较为明显地显示出较低的挥发分燃尽度、固定炭燃尽度和煤燃尽度，这表明惰质组的燃烧性能比镜质组差。但由于矿物质影响的存在，使得一些煤中显微组分富集样的燃烧性质表现出随显微组分组成更为复杂的变化。     

O2／CO2煤粉燃烧对矿物质成灰行为的影响

通过乌兰木伦煤在高温沉降炉中的燃烧实验,研究了O2/CO2燃烧时煤中矿物质的成灰行为.通过对所生成灰样的详细分析,并和O2/N2气氛下煤灰特性比较,研究了O2/CO2燃烧对矿物质成灰行为的影响.结果表明,与O2/N2燃烧相比,O2/CO2燃烧对灰样中生成的主要矿物质物相未产生显著影响,但改变了它们的相对含量;煤粉在O2和CO2体积比R为1:4条件下燃烧时,亚微米颗粒的生成量在较空气燃烧时减少,而当O2和CO2体积比R为2:3时,亚微米颗粒的生成量较相同氧浓度的O2/N2燃烧时大幅度增加;燃烧气氛还显著地影响亚微米颗粒的元素组成.     

污泥与秸秆掺烧的燃烧特性研究及应用

利用热重分析法对某城市污泥和秸秆及其混合样的燃烧特性进行了分析研究,结果表明,在加热速率20℃/min,温度为20¹ 000℃,空气气氛下,污泥和秸秆及其混合样燃烧的失重特性和燃烧性能存在差异。单一污泥试样的着火温度为334.2℃,试样着火后,燃烧速率并不高,不能快速形成较高的燃烧温度,且燃烧过程不均匀。污泥中掺入秸秆后,秸秆中的挥发分在低温区大量析出和燃烧,增加了反应的剧烈程度,提高了混合样的燃烧稳定性和燃尽水平。随着秸秆掺混比例的增加,混合试样的着火点温度明显降低、最大燃烧速率出现的温度提前、可燃性指数逐渐增加。当秸秆的掺混比为20%,混合样品的低位发热量达到13 911 kJ/kg。     

不同热转化条件下秸秆灰的熔融特性研究

生物质灰熔融特性的影响因素众多,为了系统地研究生物质灰在不同热转化条件下的熔融特性,以小麦秸秆为例,系统研究了反应温度、热解气氛、O₂体积分数等变量对麦秆灰熔融特征温度的影响规律,探究了麦秆灰的熔融特性。结果表明：随着热解温度升高,灰熔融特征温度升高,这是因为温度升高,碱金属随之挥发,而碱金属含量越低,熔融温度越高;随着气化温度升高,软化温度、半球温度、流动温度变化都不明显,但变形温度明显升高。温度的改变会造成麦秆灰残余矿物质的变化,低温物质转变为高温物质,熔融特征温度进而发生变化。反应气氛改变,麦秆灰的熔融特征温度也会发生变化。在O₂体积分数为6%～18%时,灰熔融特征温度并无明显变化。     

The physicochemical properties of different biomass ashes at different ashing temperature

There are no specific standards for biomass ash analysis in China, so the standards for coal ash analysis are usually used to determine the property of biomass ash. Three kinds of biomass including rice straw, pine sawdust and Chinese Parasol Tree leaf burned at 815 °C, 600 °C and 500 °C respectively corresponding to the temperature required in the standard of GB and ASTM. The ash content and composition were analyzed. Based on the ash composition results, the volatilization of alkali oxides in biomass ash and slagging/fouling problems related to biomass thermochemical conversion were investigated. The alkali metals were relatively more volatile with the increasing of ashing temperature. The crystalline phase composition and surface morphology characteristics of the ash particles were investigated by XRD and SEM analysis. The increasing ashing temperature resulted in the decreasing of the diffraction intensities of metal salts and the increasing of the diffraction intensities of silicon compound. Ash fusion temperatures were measured by 5E-AFII Ash Fusion Analyzer. The results indicated that the ash content, composition, crystalline phases composition, surface morphology and ash fusibility were all closely related to ashing temperatures. The analysis at 600 °C ashing temperature was regarded as the optimal for an exact determination of ash properties.     

生物质循环流化床飞灰烧失特性研究

选取2家典型生物质电厂除尘器处的飞灰,通过热重-傅里叶红外光谱联用（TG-FTIR）、X射线荧光光谱（XRF）、能谱（EDS）和X射线衍射（XRD）等分析手段,对飞灰的成分及其在高温下的失重特性进行研究。研究发现,生物质飞灰的高温失重机理较为复杂,在空气中加热时,碱金属氯盐的蒸发从380 ℃开始缓慢进行,600 ℃以下主要进行未燃碳的燃尽与碳酸镁的分解;600~750 ℃主要进行碳酸钙的分解;750 ℃后蒸发速度迅速上升,直至950 ℃完全蒸发;950 ℃以上发生矿物质的玻璃化反应和碱金属硫酸盐的蒸发。鉴于目前电力行业和ATSM对生物质飞灰含碳量的测试结果均不准确,该根据生物质飞灰的烧失机理,提出更加精确的氮气和空气气氛下600 ℃烧失量之差含碳量测试方法。     

准东煤灰与液态排渣煤粉炉耐火材料的烧结特性

采用TGA-DSC分析确定了准东煤灰和其混合灰样(不同质量比的准东煤灰和耐火材料)燃烧过程中的特征温度,并分别采用XRD和FSEM-EDS对不同特征温度段灰样进行矿物识别和形貌、能谱分析,得到了原灰与混合灰的烧结温度、灰中主要矿物的转化和熔融过程,并对比了不同耐火材料含量的煤灰熔融温度;在此基础上提出了耐火材料构型的极...     

保温用天然生物质材料的热湿特性

实验分析一些廉价天然材料(椰壳和花生壳)的导热特性。利用同心球稳态测量方法测量确定椰壳和花生壳的导热系数,以及导热系数随温度的变化规律,同时以硅酸铝纤维材料为标准试样,与天然材料的导热性能进行对比分析。还对这些材料的低温吸湿作了初步测试,分析此类材料作为低温绝热材料的吸湿特性。研究结果表明,所有材料的导热系数均随温度的升高而增大,且增大速率都近似相等。影响天然生物质材料导热性质的因素主要有：纤维或多孔固体材料中的导热、孔隙中空气的对流换热,如果温度足够高的话,还有辐射换热。     

Mineral transformation during combustion of coal blends

Mineral behaviour for two individual coals (I, J) and their two‐component coal blends and 800°C ash blends heating were studied. Ash samples were heated progressively from 800°C to IT (initial deformation temperature) at 100°C intervals under different conditions. Coal samples were heated from room temperature to the corresponding temperature. Mineral transformation at each temperature was determined by X‐ray diffraction and SEM measurements. The results show that Si, Al, Fe and Ca compounds have a great form variation during heating. Their forms at different temperatures depend on the chemical composition of the ash, the blending ratio and the atmosphere. For different coal ashes, the main mineral matters at 800°C were quartz, anhydrite, hematite, calcite and feldspar. As the temperature increased, oxidation, thermal decomposition, transformation and reaction occurred between the components. Comparing a 40% I+60% J ash blend with individual ashes, fayalite was formed at 1100°C for the blend; the reaction product existed in a glassy phase at 1300°C. For a coal blend having the same ash ratio as the ash blend, FeO reacted with amorphous SiO₂ or Al₂O₃ to form fayalite and hercynite at 1000°C. As the temperature increased to 1100°C, fayalite and hercynite increased obviously. At 1200°C, some iron inclusion compounds melted to become glassy phase matter. Compared with the ash blend, iron species undergo a different change during coal blend heating: fayalite and hercynite formed earlier, iron compounds melted to form a glassy phase at lower temperature. This may be caused by early combustion of the more reactive coal (J coal) in the blend inducing local variation in oxygen concentration gradients around the less reactive coal and consequently affecting the reaction atmosphere and Fe mineral behaviour and interaction. That is to say, for coal blends, the mineral transformation was affected by both the mineral species interaction and the combustion behaviour. The calculations were performed to examine the fate of mineral matter under different combustion conditions using a thermodynamic chemical equilibrium calculation program. Calculations from coal blends were comparable with experiments from ash blends, this is because the calculation program only considers the interaction among the mineral species but does not consider the combustion reaction. It indicates that combustion and the relative volatiles also affected the mineral behaviour and slagging during coal blend combustion. Meanwhile, the mineral species evaporations were measured at high temperature: the main evaporated species were Na, K pure species and compounds, Fe, FeO, SiO and SiO₂. The evaporation of Fe has an important effect on initial deposition. Calculations were comparable with the experiments. Copyright © 1999 John Wiley & Sons, Ltd.     

Burning of antimony/potassium permanganate pyrotechnic compositions in closed systems

The antimony/potassium permanganate system is not gasless although it is used in sealed electric delay detonators. Burning rates of identical compositions vary according to the extent to which the system is confined. The variation is especially marked for the high fuel compositions which are the less gassy. Pressure profiles and burning rates have been measured in simulated detonators, with and without venting. For high fuel compositions, sealing the system increases the burning rate considerably. When the proportion of fuel is lower, the effect is not as great. The low fuel compositions form a solid product slag which tends to seal the column and force the hot oxygen gas evolved during decomposition of the KMnO₄ forward. The unburned powder is thus brought more rapidly to its ignition temperature (∼500°C) and the burning rate is increased. The high fuel compositions give a molten product and thus the ignition chamber must be sealed to ensure forward movement of hot gas.     

Thermogravimetric kinetic analysis of Nannochloropsis oculata combustion in air atmosphere

The thermal behavior of Nannochloropsis oculata combustion in air atmosphere were investigated by performing experiments on STA PT1600 Thermal Analyzer at heating rates of 10°C/min, 40°C/min and 70°C/min and range of temperatures from room temperature to 1200°C. The kinetic parameters were evaluated by using Kissinger and Ozawa methods. The result showed that Nannochloropsis oculata combustion occurred in five stages. Started with initial devolatilization, the main thermal decomposition and combustion process, transition stage, the combustion of char and the last stage was the slow burning reaction of residual char. In line with increasing heating rate, the mass loss rate increased as well, but it delayed the thermal decomposition processes toward higher temperatures. The average activation energy at the main thermal decomposition stage and the stage of char combustion were approximately 251 kJ/mol and 178 kJ/mol, respectively.     

Geochemical study of fluid inclusions from the western upflow zone of the Matsukawa geothermal system,Japan

Prior to development, the Matsukawa geothermal field was partially vapor-dominated. The youngest mineral assemblage consists of early pyrophyllite, diaspore and pyrite, and later anhydrite and quartz, implying deposition from an acidic, high-temperature fluid. Fluid inclusions in anhydrite and quartz from core and cutting samples collected in wells drilled in the western upflow zone of the field were studied to characterize the temperatures and compositions of these late fluids.The results of fluid inclusion studies indicate that the temperatures during the deposition of anhydrite and quartz were up to several tens of degrees lower than the reservoir temperatures at the time of exploitation. Fluids trapped in anhydrite had temperatures of up to 257 °C, CO₂ concentrations in the 0.4–2.6 mol% range and salinities of 1.9–11.3 wt.% NaCl. This compositional variation is related to vapor loss occurring during boiling. The data suggest that the geothermal reservoir is currently being reheated by subvolcanic intrusions.     

Oxygen isotopic ratios of sulfate ions-water pairs as a possible geothermometer

In this paper a brief review is given of the dependence of the oxygen isotopic fractionation of the sulfate ions-water system on temperature and the pH. From the available experimental data some relationships have been elaborated, which show that the isotopic exchange time is strongly temperature and pH dependent. The times for 97 per cent of isotopic exchange (near equilibrium conditions) at pH 7.0 are about 9 years at 200°C and 0.6 years at 330°C, while at pH 3.8 and at the same temperatures the times of exchange are 1.5 years and 0.08 years respectively. Thus, at the temperatures and pH of geothermal reservoirs the sulfate could be in isotopic equilibrium with environmental water, and the oxygen isotopic fractionation factors of sulfate-water geothermal pairs, being temperature dependent, can be used as geothermometers.Also reported here are some results on the O¹⁸ content of sulfate-water pairs from some wells on the edge of and outside the Larderello geothermal basin. The estimated isotopic temperatures are not very significant for the deep reservoir temperatures due to the geological features of the Larderello area which show important outcropping and deep anhydrite layers. Furthermore, as regards the wells outside the Larderello basin (Travale wells) some mixing of the geothermal water with colder underground water has been proved. However, the isotopic temperatures are generally higher than those measured at the well-head, and the highest ones are close to those estimated for the geothermal reservoir.In other geothermal areas more convenient from a geological point of view, the O¹⁸ content of the sulfate-water pair can be a useful and accurate thermometer.The O¹⁸/O¹⁶ ratios of several other sulfates (surface and deep anhydrite samples, sulfate ions in thermal springs) from the same area were also determined and differ substantially from borehole sulfate values.     

不同生物质灰的理化特性

根据我国和美国国家标准,将稻草、松木屑和梧桐树叶3种生物质分别在815和600℃下制灰,此外也在500℃下制灰进行比较。测定了灰分量和灰成分,考察了灰成分中氧化物的含量变化以及生物质灰的积灰、结渣特性;利用X射线衍射方法和SEM对不同温度灰的物相和灰形态进行了分析;利用灰熔点仪测定了生物质灰的灰熔点。研究表明:灰分量、灰成分、物相变化、灰形态以及灰熔点均与灰化温度密切相关,600℃的灰化温度比较适合研究生物质灰分的性质。