降低炉底飞灰含碳量的几点技术措施

针对流化床煤气化技术飞灰含碳量高的情况，华中科技大学煤燃烧国家重点实验室提出降低炉底渣含碳量3项技术措施并研究开发外部流化床反应器。     

飞灰循环底饲回燃流化床燃烧技术

在一输入热功率０．３ＭＷ的试验装置上进行了飞灰循环底饲回燃流化床燃烧试验，研究了循环倍率，飞灰回送方式和运行参数对燃烧特性的影响，开发出该项燃烧技术。     

降低循环流化床锅炉飞灰含碳量的因素分析

循环流化床锅炉的飞灰含碳量是锅炉燃烧工况好坏的直接反映 ,其对锅炉的热效率的影响是很大的 ,它还直接影响着粉煤灰的综合开发和利用 .在对云天化循环流化床锅炉的生产实验研究中 ,分析了影响循环流化床锅炉飞灰含碳量的各种因素 (床温、煤质煤粒、一次风、二次风、床压和旋风分离器效率等 ) ,通过实验研究找到了降低循环流化床锅炉飞灰含碳量的具体而又行之有效的操作方法 ,以指导实际生产 .     

循环流化床锅炉飞灰含碳量的研究

循环流化床锅炉具有高效、低污染、煤种适应性广等优点。但我国流化床锅炉普遍存在着飞灰含碳量高,锅炉燃烧效率达不到设计值的问题。概述了影响飞灰含碳量的主要因素:如煤种、燃煤的粒径及风量等,重点探讨了燃煤的粒径对飞灰含碳量的影响,提出了维持锅炉稳定,降低飞灰含碳量,提高燃烧效率的一些措施。     

循环流化床锅炉飞灰含碳量的测定方法探讨

对循环流化床锅炉飞灰的烧失量和含碳量进行了对比 ,烧失量与含碳量差别很大。传统上用烧失量代替含碳量对循环流化床锅炉飞灰并不适用。本文提出用煤的工业分析方法测定循环流化床锅炉飞灰的含碳量 ,并测出循环流化床锅炉飞灰含碳量随粒径分布的变化关系。     

循环流化床锅炉炉渣和飞灰含碳量高的原因及降低措施

循环流化床锅炉炉渣含碳量和飞灰含碳量高是影响锅炉热效率的主要原因之一,降低炉渣含碳量和飞灰含碳量成为循环流化床锅炉节能降耗的主要工作。针对循环流化床锅炉的炉渣含碳量和飞灰含碳量偏高采取了措施,大大提高了锅炉效率和电厂的经济效益。     

锅炉飞灰燃烧特性实验研究

锅炉飞灰中含碳量高不但导致了锅炉燃烧效率的降低，也限制了飞灰的再利用。因此，降低飞灰含碳量，充分利用其化学能，具有较高的经济价值，对石家庄东方热点公司锅炉飞灰的粒径分布、烧失量分级分布和燃烧特性进行了研究。结果表明，通过飞灰再燃可以有效地降低飞灰中的含碳量，并在实验室小型鼓泡流化床上进行了飞灰再燃降低含碳量的验证实验。     

循环流化床粉煤气化炉的发展及大型化措施

采用空气流态化燃烧，蒸汽流态化气化，利用温度差，间歇煤燃烧，煤气化制气技术，成功地开发ＦＭ１．６循环流化床粉煤气化炉。并介绍了气化炉大型化的措施和采用φ２５００粉煤气化炉技术改造化肥厂块煤固定床气化炉的可行性。     

水煤浆气化炉内飞灰的形成机理

基于实验室规模的多喷嘴对置式水煤浆气化炉,利用SEM、马尔文激光粒度仪和XRD表征气化炉内飞灰的粒径分布和组成,并分析了气化炉内飞灰的形成机理。结果表明,喷嘴平面处飞灰与气化炉出口处飞灰的粒径分布及化学组成存在显著差异,不同气化阶段飞灰的形成机理也不同。气化燃烧阶段飞灰的形成机理为部分固定碳燃烧和外在矿物转化,而在焦炭气化反应阶段,飞灰的形成机理为焦炭破碎和内在矿物释放及转化。     

循环流化床气化细粉灰熔融特性

因为流化床气化技术的优点非常多,主要包括：床层温度均匀、传热效率大、煤种范围广等等,所以被广泛用于煤气化中。不过流化床气化炉的操作温度比较低,使得气化细粉灰的含碳量较大。因此,为了有效加强碳的使用效率,减小环境污染,就对循环流化床气化细粉灰熔融特性展开了研究,借助测定仪、X射线衍射仪以及扫描电子显微镜等设备能够良好找到温度、气氛和残炭含量等因素对循环流化床气化细粉灰熔融特性的主要影响,给循环流化床技术的应用和发展带来很大的帮助。     

流化床-气流床耦合反应器中煤气化特性

利用化工动力学软件CHEMKIN建立了流化床-气流床耦合反应器等效网络模型,在φ300 mm反应器中的煤气化实验结果基础上,充分考虑耦合反应器不同区域物料间两相流动、传质传热,对耦合反应器各部分流体力学特征以及耦合反应器中不同区域的化学反应进行了分析。利用模型对飞灰的碳转化率、耦合反应器的碳转化率、耦合反应器内温分布及物料停留时间进行计算,结果表明,流化床耦合气流床反应器后,气流床可将出口飞灰碳转化64.1%,实现了耦合反应器对飞灰的再气化;耦合反应器煤气化系统的碳转化率由单独流化床的84.9%提高到92.2%。     

磨细矿物掺合料对水泥硬化浆体孔结构及砂浆强度的影响

采用压汞法研究了钢渣、矿渣、粉煤灰单掺或复掺对水泥硬化浆体孔结构的影响.同时还研究了掺合料单掺或复掺对水泥砂浆抗压强度的影响.结果表明:掺合料单掺或复掺对早期水泥硬化浆体的孔结构有一定的劣化作用;水化后期,矿渣与钢渣均明显降低了水泥硬化浆体的孔隙率,矿渣与粉煤灰均明显降低了水泥硬化浆体的中值孔径并改善了水泥石的孔径分布,掺合料复掺对改善水泥硬化浆体的孔结构有积极作用,尤其是掺合料三元复合可取得最佳的效果.3种掺合料降低水泥硬化浆体孔隙率能力的大小顺序为:矿渣>钢渣>粉煤灰.3种掺合料降低水泥硬化浆体孔径并改善孔径分布能力的大小顺序为:矿渣>粉煤灰>钢渣.掺合料降低了水泥砂浆早期的抗压强度,却增加了水泥砂浆90 d的抗压强度.掺合料的活性大小顺序为:矿渣>钢渣>粉煤灰.     

气流床煤气化炉壁面反应模型

建立了气流床煤气化炉煤灰渣颗粒沉积和壁面反应模型,相应完善了渣层流动、传热传质和相变模型,发展了数值模拟方法,并以国内某型两段式干煤粉加压气流床煤气化中试炉为对象进行了模拟。利用建立的模型可以得到壁面反应速率、渣层含碳量、固态渣层厚度、液态渣层厚度、渣层平均温度和液态渣层平均速度等。结果表明:氧煤比升高,渣层平均温度升高,固态渣层厚度、液态渣层厚度和气化炉出口灰渣含碳量降低。计算得到的灰渣含碳量在14%左右,整体碳转化率为95.2%左右,与实际值相近。通过模拟发现壁面反应对于所分析气化炉的碳转化率、排渣含碳量、壁面渣层流动和温度状态具有重要影响,进而影响气化炉的安全稳定运行。     

粉煤灰海工高性能混凝土的应用研究

针对粒化高炉矿渣粉和硅灰存在的缺陷。研究采用粉煤灰替代粒化高炉矿渣粉配制混凝土,进而观察其力学性能、抗氯离子渗透性以及胶凝材料的水化热。研究结果表明,所配制的混凝土能满足海工高性能混凝土高耐久性的需要,粉煤灰替代粒化高炉矿渣粉胶凝材料具有较低的水化热,有利于大体积混凝土的施工。     

岩棉炉渣水硬活性及其水泥砂浆的耐久性分析

为循环利用岩棉生产过程中排出的炉渣废料,将其磨成3个细度的粉体,分别与岩棉纤维粉、粉煤灰和粒化高炉矿渣粉(简称矿粉)进行对比分析.结果表明:炉渣主要化学成分及含量接近粉煤灰.炉渣中玻璃体含量较高,同时存在少量结晶相,结晶度为5.28％.提高炉渣粉磨细度可显著增加活性.450 kg/m2比表面积的炉渣粉强度活性指数比粉煤灰高出约10％,低于同等细度的矿粉.掺入炉渣粉的水泥砂浆试件抗渗和抗冻性优于粉煤灰砂浆,而低于矿粉砂浆试件.孔结构测试分析表明,炉渣粉水泥砂浆孔隙率和多害孔含量介于矿粉水泥砂浆和粉煤灰水泥砂浆之间.粉磨制备的岩棉炉渣粉体具备作为矿物掺合料的可行性.     

Selection of IGCC candidate coals by pilot-scale gasifier operation

Nine imported coal samples were tested to make the guidelines for IGCC (Integrated Gasification Combined Cycle) candidate coals — the guidelines that are applicable in future commercial IGCC plants in Korea. Entrained-bed slagging gasifier whose maximum capacity is 3 ton/day has been operated under pressure ranges of 10–29 bar. The factors considered were conversion efficiencies, moisture content, sulfur content, ash content, ash melting temperature, slag viscosity, slag characteristics, and coal reactivity. The best coal type for IGCC applications appears to be the one that contains low ash content with low-enough slag viscosity and high reactivity in coal. However, coal that exhibits high fluidity at the gasifier exit resulted in higher probability in plugging by fly-slag, so that the coal of ash fluid temperature lower than 1260 °C would require precaution for utilizing the feedstock in the entrained-bed gasifier. Conventional ash fusion measurement data might disagree with slag viscosity results in estimating the optimal operation temperature, and thus actual viscosity tests on slag would be necessary.     

Crystallisation behaviour of blast furnace slag modified by adding fly ash

Crystallisation of molten blast furnace (BF) slag can increase its viscosity, which can in turn affect the quality of slag fibres. Fly ash was added to BF slag to control its crystallisation and modify its chemical composition. FactSage simulation and analyses using X-ray diffraction (XRD), scanning electron microscope-backscattered electrons (SEM-BSE) coupled to an energy dispersive spectrometer (EDS), and single hot thermocouple technique (SHTT) were performed to explore the crystallisation behaviour of the modified BF slag. The relationship between temperature, mineral precipitation, and added fly ash content was investigated. The minerals contained in the modified BF were melilite, anorthite, clinopyroxene, and spinel. Variation in the fly ash content did not change the composition of the precipitate, but changed its content and the crystallisation temperature of the minerals, which affects the initial crystallisation temperature of the modified BF slag. It decreased as fly ash content increased, and was influenced by the crystallisation of melilite when the added fly ash content was between 5% and 20%. When the added fly ash content increased to 25%, the initial crystallisation temperature was influenced by the precipitation of anorthite. The initial crystallisation temperatures obtained by FactSage simulation, XRD analysis, and SHTT experiments differed due to kinetic effects. The modified BF slag with a fly ash content of 15% is considered suitable for manufacturing of slag fibres due to its low initial crystallisation temperature and cost.     

粉煤灰和磨细矿渣对高强轻骨料混凝土抗渗及抗冻性能的影响

研究了粉煤灰和磨细矿渣对高强轻骨料混凝土抗渗及抗冻性能的影响。结果表明：粉煤灰和磨细矿渣的复合掺入能显著提高高强轻骨料混凝土的强度、抗渗及抗冻性能。在不掺入引气剂的情况下,轻骨料混凝土的抗冻性达F200以上。轻骨料混凝土的扫描电镜照片表明：粉煤灰和磨细矿渣的综合效应,使火山灰反应更加充分,Ca(OH)2含量降低,轻骨料与水泥石的界面过渡区得到强化,混凝土结构更加密实,其抗渗、抗冻性能得到进一步提高。     

超低排放燃煤机组硒的迁移转化及飞灰对其富集特性

采用微波消解法和氢化物发生-原子荧光光谱法考察了9台超低排放在役机组硒迁移转化规律,探究了循环流化床（CFB）和煤粉炉（PC）机组飞灰特性差异对硒吸附能力的影响。燃烧后煤中硒几乎全部呈现挥发态,底渣中残留量极低。与浓度归一化和质量分布法相比较,相对富集系数法可以客观地评价燃煤副产物中硒的富集能力,两类机组中硒均主要富集于飞灰中。CFB较低炉膛温度和添加CaO可以降低入炉煤中硒释放比例并增强飞灰对硒的吸附能力,故其底渣和飞灰中硒的富集程度均高于PC,导致脱硫石膏中硒富集程度低于PC。飞灰对硒的吸附量随比表面积或孔容积增大而增大,但随粒径或孔径增大而减小。CFB飞灰中未燃尽碳含量高、形状不规则、表面粗糙且存在较多蜂窝状孔隙,导致其对硒的富集程度高于PC飞灰。     

多喷嘴对置式气化炉中飞灰性质

On a laboratory scale opposed multi-burner gasifier (OMBG), the fly ashes at different sampling mouths are collected and analyzed by SEM, EDS, XRF and Malvern mastersizer. Most fly ash particles produced in the gasification are irregular, aggregate or spherical. As for the composition of the particles, carbon is the main content, while S, Fe and Na get enriched. At the same time, the concentration of Al and Si in the fly ash particles is lower than that in the original slag. From the nozzle plane to the exit of gasification chamber, the carbon content of particles decreases along the axes of gasifier. The carbon content of particles decreases rapidly from the nozzle plane to No. 7 sampling mouth and declines slowly from No. 7 sampling mouth to the chamber exit. The size of particles generated in the gasification appears a triple-humped-distribution with peaks at 0.1—0.2 μm, 2 μm and 14 μm. The particle size distribution in different sampling places is different. Above the impact plane, more ultra-fine particles are found and coarse particles are larger in location near the impact plane. In symmetrical up and down locations of the impact plane, the particle size distributions are similar, but there are more coarse particles below the impact plane. The coarse particle size decreases and the proportion of fine particles increases below the impact plane, while the proportion of coarse particles increases at the chamber exit.