脱硫灰渣用作水泥活性混合材料的试验研究

研究了同一厂家的三种脱硫灰渣作为水泥活性混合材料对普通硅酸盐水泥性能的影响.结果表明同一厂家的三种脱硫灰渣性能差异较大,但当掺量不超过7.0％时,与水泥熟料、石膏等共同粉磨制成的普通硅酸盐水泥物理力学性能以及体积安定性满足相关国家标准要求.     

利用脱硫灰渣制备生态水泥

在少量金属盐激发剂作用下，利用脱硫灰渣等固体废弃物制备生态型胶凝材料。通过调节激发剂、调整剂的用量、脱硫灰渣和矿渣的配比，研究各因素对水泥抗压强度及综合性能的影响。研究结果表明：激发剂可以激发脱硫灰渣的活性，其用量对强度影响最明显，矿渣和脱硫灰渣合理搭配有利于提高体系的综合性能，当矿渣与脱硫灰渣比为60：40时具有最佳的协同作用。     

我国脱硫灰渣资源化综合利用现状

阐述了脱硫灰的成分与特点以及目前我国对脱硫灰渣的利用现状,并分析了影响脱硫灰渣利用的主要因素和资源化利用提出的建议,对脱硫灰渣的进一步研究和发展提供一些有益的参考。     

激发脱硫灰渣对水泥微观结构的影响

分别以氢氧化钠和以硫酸盐为主复配两种激发剂,来激发脱硫灰渣.应用XRD和FESEM分析激发剂对脱硫灰渣和脱硫灰渣配制的水泥微观结构的影响.结果表明:激发剂能使脱硫灰渣的Si-O、Al-O键重排,激发了脱硫灰渣中的活性物质,并且有凝胶状物质生成;激发剂能使脱硫灰渣配置的水泥中的无水石膏快速溶解,促使水化产物分布均匀且减少了膨胀性物质的生成.激发后的脱硫灰渣配制的水泥水化28 d的微观结构密实,宏观上表现为水泥强度有所提高.     

石油焦脱硫灰渣用作水泥调凝剂的研究

研究了石油焦脱硫灰渣用作水泥缓凝剂对水泥性能的影响.研究结果表明,石油焦脱硫灰渣主要舍无水硫酸钙、氧化钙和碳酸钙,单独使用作水泥缓凝剂会使凝结时间明显缩短.与单掺脱硫石膏标准样相比,石油焦脱硫灰渣与脱硫石膏双掺用作水泥缓凝剂,其凝结时间变化不大,强度相近,与减水剂相容性较好.石油焦脱硫灰渣与脱硫石膏双掺用于混合材掺量较大的通用硅酸盐水泥缓凝剂,其强度等性能还有所改善.     

CFB脱硫灰渣的性能及应用研究

对以褐煤和烟煤为燃料的CFB脱硫灰渣进行基本物理化学性能及矿物组成和火山灰性能试验,及用于建材行业的各项性能试验,为CFB脱硫灰渣在建材行业的应用提出建议。     

粉煤灰与脱硫灰渣的硫含量测定问题

一部分燃煤电厂实施烟气脱硫后,导致粉煤灰或脱硫灰渣含有亚硫酸钙。此时如果仍用GB/T176-1996《水泥化学分析方法》中所列方法测定灰渣的硫含量,存在于亚硫酸钙中的硫大部分不能测出,以致会把SO3含量大于3%的脱硫灰渣误作为合格粉煤灰用于水泥混合材和混凝土掺合料。建议尽快制定测定此类灰渣新的相关标准。     

循环流化床锅炉脱硫灰渣综合利用研究

在系统分析阐述循环流化床锅炉脱硫灰渣特性的基础上,探讨了各种综合利用方式,并推荐以烧结为主的脱硫灰渣利用方法.由此研制出了烧结砖、植料等产品,可带来可观的经济效益和环保效益.     

脱硫灰渣的排放方式及利用

火电厂产生的脱硫灰渣的组成和性能与其排放方式有着密切关系。为使其得到较好的处置与利用 ,本文从排放方式方面进行探讨 ,并略述各种脱硫灰渣的性能与利用前景     

循环流化床锅炉炉内脱硫灰渣的水化特性研究

比较循环流化床(CFB)锅炉炉内脱硫灰渣与粉煤灰的性质的差异;分析炉内脱硫灰渣的水化胶凝特性,指出活性的Al2O3和活性的SiO2等无定形物质是CFB锅炉灰渣的活性来源,脱硫灰渣中大量存在的CaO和Ⅱ-CaSO4成分对火山灰活性起到了激发作用,使其具有更加明显的胶凝性质;认为CaO和Ⅱ-CaSO4是参与脱硫灰渣水化反应的主要物质,水化过程形成的钙矾石是引起水化产物膨胀的主要原因,水化后SO2-4的浓度对钙矾石的长期稳定性有着关键影响,而灰渣中的CaO对水化过程的体积膨胀则起到间接作用.     

LiBr在丙酮与水的混合溶剂中溶解度的测定与关联

使用静态法常压下分别测定了LiBr在不同质量百分比的丙酮与水的混合溶剂(水的质量分数为10％ ～40％)中293.15 ～323.15 K范围内的溶解度,并利用LIFAC模型及其参数推算了活度系数及溶解度,计算值与试验值的总平均绝对偏差和总平均相对偏差百分比分别是0.054 0和0.731 3％.结果表明,LIFAC模型可以用来预测LiBr在丙酮与水的混合溶剂中的溶解度.     

燃煤灰渣活性差异及来源研究

粉煤灰、沸腾炉渣和固硫灰渣是三种具有代表性的燃煤灰渣,因生成方式与生成温度不同,火山灰活性存在较大差异。本文采用改进的28 d抗压强度比方法研究其活性差异,并在矿物组成及颗粒形貌等方面探讨活性差异来源。研究结果显示:沸腾炉渣和固硫灰渣活性相近,明显高于粉煤灰;不同种类燃煤灰渣的活性差异主要来源于其矿物组成及颗粒形貌差异。     

LIFAC脱硫粉煤灰在水泥砼中的应用研究

对用于水泥和混凝土的LIFAC脱硫粉煤灰技术指标和水泥混凝土的强度发展进行了测定和分析 ,对LIFAC脱硫粉煤灰中的游离氧化钙对水泥混凝土体积稳定性的影响进行了研究     

Effect of bed materials and additives on the sintering of coal ashes relevant to agglomeration in fluidized bed combustion

Agglomeration propensity of Thai low-rank coal ashes was determined by measuring the compressive strength of sintered ash pellets over the temperature range of fluidized bed combustion. Physical and chemical changes of the sintered products were ascertained from scanning electron microscope-energy dispersive X-ray detection (SEM-EDX) and X-ray diffractometry (XRD). A clear difference existed in the strength–temperature relationship between these ashes. This difference was attributed to the role and relative amounts of clays and anhydrite components that form the low temperature melting eutectics. The bed materials (sand, CaO, CaCO₃, and CaSO₄) and additives (gibbsite and andalusite) when combined with the ashes caused a strength reduction due to the inert dilution effect that prevented the interaction of anhydrite and clays. To comprehend the mechanism of sintering and bed agglomeration more clearly, modified ashes which produced extra amount of amorphous silicate materials were prepared and tested. The bed materials and additives, when sintered with these modified ashes, gave reduction of pellet strength by varying extents based on three possible mechanisms namely, a pure inert effect, an inert/reaction effect and an inert/adsorption effect, with gibbsite being the most effective. Of the four test ashes, Lanna ash was the only ash that exhibited almost no strength development under all conditions, due principally to its very low clays content and relatively stable forms of mineralogical compositions.     

Speciation of mercury in fly ashes by temperature programmed decomposition

Mercury (Hg) is a toxic trace element which is emitted mostly in gas phase during coal combustion, although some Hg compounds may be retained in the fly ashes depending on the characteristics of the ashes and process conditions. To improve the retention of Hg in the fly ashes a good knowledge of the capture mechanism and Hg species present in the fly ashes is essential. The temperature programmed decomposition technique was chosen to identify the Hg species present in fly ashes obtained from two Pulverized Coal Combustion (PCC) plants and a Fluidized Bed Combustion (FBC) plant. The fly ashes were then used as Hg sorbents in a simulated flue gas of coal combustion and gasification. The Hg compounds found in the fly ash from the FBC plant after elemental mercury retention were mainly HgCl₂ and HgSO₄. The Hg species present in the two fly ashes from the two PCC plants were HgCl₂ and Hg⁰. The Hg species formed in the coal gasification atmosphere was HgS for all three fly ashes. The only Hg compound identified in the fly ashes after the retention of mercury chloride was HgCl₂.     

循环流化床锅炉飞灰增湿低温悬浮脱硫特性

以循环流化床锅炉飞灰作为实验对象,研究增湿活化飞灰在低温悬浮反应器中的脱硫特性。实验结果表明：增湿低温悬浮脱硫过程中,当水钙比能保证反应器中增湿灰的悬浮流化状态时,反应温度对钙利用率存在促进与抑制作用。水钙比为1时,钙利用率随反应温度的升高而增大;水钙比为3、5时,钙利用率随反应温度升高先升高后降低;水钙比为10时,钙利用率随反应温度的升高而降低;当水钙比为10,飞灰增湿低温悬浮脱硫可将循环流化床锅炉飞灰初始钙利用率由41%提高至60%左右,最佳反应温度在60～80℃之间。扫描电镜表明,飞灰增湿活化后,飞灰颗粒表面空隙增多、产生裂缝,有利于进一步在悬浮反应器中脱硫。     

Effects of three Turkish fly ashes on the heat of hydration of PC-FA pastes

Effects of the type and amount of fly ash substitution on the heat of hydration of portland cement-fly ash pastes were investigated. Three Turkish fly ashes were used. One of them was a high-calcium and the other two were low-calcium fly ashes. The specimens contained 0, 10, 20, and 40% fly ash by weight of portland cement. The tests were carried out as described in ASTM C 186 however one separate set of specimens were first subjected to an early external temperature of 67±2°C for six hours followed by the standard temperature until time of test. The results revealed that the low-calcium fly ashes, regardless of their type, reduce the heat evolution when used for partial cement replacement. The high-calcium fly ash, on the other hand, does not produce significant changes in the heat of hydration.     

High temperature elemental losses and mineralogical changes in common biomass ashes

The elemental losses from ashes of common biomass fuels (rice straw, wheat straw, and wood) were determined as a function of temperature from 525 °C to below 1525 °C, within the respective melting intervals. The experimental procedure was chosen to approach equilibrium conditions in an oxidizing atmosphere for the specific ash and temperature conditions. All experiments were conducted in air and used the ashes produced initially at temperatures of 525 °C as reactants. Losses during the initial ashing at 525 °C were negligible, except for a K₂O loss of 26% for wood and a Cl loss of 20% for wheat straw. Potassium losses are positively correlated with temperature for all fuel ashes. The K₂O loss for wood ash commences at 900–1000 °C. Carbonate is detected in the wood ashes to about 700–800 °C and thus cannot explain the retention of K₂O in the ashes to 1000 °C. Other crystalline phases detected in the wood ashes (pericline and larnite) contain little or no potassium. Petrographic examinations of high temperature, wood ash products have failed to reveal potassium bearing carbonates, sulfates, or silicates. The release of potassium, thus, appears to be unrelated to the breakdown of potassium-bearing crystalline phases. The straw ashes show restricted potassium loss compared to wood ash. The potassium content declines for both straw ashes from about 750 °C. Cristobalite appears in the straw ashes at about 700–750 °C and is replaced by tridymite in the rice straw ash from about 1100 °C. Sylvite (KCl) disappears completely above 1000 °C. The Cl content starts to decline at about 700 °C, approximately at the same temperature as potassium, suggesting that the breakdown of sylvite is responsible for the losses. The K–Cl relations demonstrate that about 50% of K (atomic basis) released from breakdown of sylvite is retained in the ash. The presence of chlorine in the ash is, therefore, best attributed to the presence of sylvite. Potassium is easily accommodated in the silicate melt formed at temperatures perhaps as low as 700–800 °C from dehydration, recrystallization, and partial melting of amorphous components. Loss of potassium persists for ashes without remaining sylvite and points to the importance of release of potassium from partial melt at temperatures within the melting interval for the fuel ashes.     

Sintering characteristics of low-rank coal ashes

The electrical resistance and compressive strength were measured to gain a better understanding of the sintering characteristics of low-rank coal ashes involved in deposit formation in combustion systems. Low-rank coal ashes were prepared by the standard ASTM ashing procedures at 750°C and then separated into three different particle size fractions. The sinter point determined by the electrical resistance method decreased with decreasing particle size at three different particle size fractions of each coal ash. The compressive strength lest was made as a function of temperature in the range 750–950°C. At a given sintering temperature, strength of the sintered ash was inversely proportional to particle size. For any given particle size of each coal ash, the strength increased with increasing sintering temperature. X-ray diffraction of the sintered coal ashes showed that, as sintering temperature increased, there was an inverse relationship between sinter strength and the amount of anhydrite in the sintered ash, and a direct relationship between strength and the amount of hauyne.     

燃油锅炉灰垢的烧结成因及其对策

介绍了燃油锅炉灰垢的成分及其烧结成因。发现灰垢中SO含量很大,且其酸性和Fe含量均随取样点温度的升高而降低。当灰垢中组分发生化学反应时,由于离子扩散遣率加大而位烧结程度加重。清灰刘应该具有助燃、防烧结和减轻位温及高温腐蚀的作用。研制清灰剂时要加意考察清灰剂中每个组分的作用,天好过免使用易生成低熔点化合物的成金属化合物。文中还介绍了新研制的清灰剂在实验室和工业装置上的清灰效果。