垃圾焚烧炉氯源对氯化氢和二噁英排放的影响

本文研究了150 t/d垃圾与煤混烧流化床锅炉在不同含氯水平和添加钙基脱硫时氯化氢和二噁英的排放特性。实验结果表明烟气中的氯化氢和二噁英浓度随燃料中垃圾比例的增加而上升,在含氯量一定的情况下,炉内燃烧状况决定了二噁英的生成量,烟气中的二噁英随燃料中含氯量的增加而增加,飞灰中的二噁英则随燃烧状况的改善而增加。钙基的加入可以有效降低氯化氢和二噁英的排放。在我国目前的垃圾组分条件下,全煤工况和垃圾与煤混烧工况的二噁英排放量很低。     

炉内喷钙脱硫过程数值模拟

建立了一套较为完整的对炉内喷钙脱硫过程进行模拟的方法，获得了炉内气固两相流动、温度分布、石灰石颗粒脱硫化学反应和SO2浓度分布的详细情况。石灰石颗粒的硫化反应主要发生在颗粒与烟气均匀混合之前。     

高CO2浓度下钙基吸收剂脱硫的实验研究

本文进行了高CO2浓度下钙基吸收剂脱硫的实验研究.结果表明,高浓度CO2下钙基吸收剂的脱硫效率随脱硫时间的变化与空气条件下显著不同.孔隙结构分析及热重分析等手段表明高CO2浓度主要影响了钙基吸收剂的煅烧分解过程,形成了有利于脱硫反应的孔隙结构.实验结果还表明提高温度有利于改善高浓度CO2气氛下钙基吸收剂煅烧后孔隙结构,在适当的脱硫时间内,高温下高浓度CO2气氛比空气气氛更有利于炉内喷钙脱硫.     

O2/CO2方式下钙基吸收剂在脱硫过程中微观结构变化的研究

本文研究了O2/CO2方式下钙基吸收剂在脱硫过程中微观结构的变化。研究结果表明,不同浓度的CO2对孔隙结构的影响完全不同;且提高温度有利于改善高浓度CO2气氛下钙基吸收剂煅烧后的孔隙结构,较之空气气氛,高浓度CO2气氛更有利于高温下炉内喷钙脱硫。     

超细CaO粉炉内喷射脱硫的实验研究

本文对超细ＣａＯ粉炉内喷射脱硫进行了实验研究，分析了可能影响超细ＣａＯ粉炉内脱硫效率的多种因素，实验结果表明：使用预先锻烧生成的超细ＣａＯ粉在并不苛刻的反应条件下脱硫效果很好，颗粒大小、反应区温度、反应时间和Ｃａ／Ｓ比对炉内喷钙脱硫的效率有重要的影响．     

城市下水污泥和煤/LPG在循环流化床上的混烧试验研究

在高6000 mm、直径300mm的循环流化床上进行了含水率为79％的湿污泥与煤／石油液化气(LPG)的混烧试验。试验结果表明:无论用煤还是LPG作为辅助燃料,试验都能在设定的工况条件下稳定运行;向炉内加入石灰石的量达到钙硫摩尔比为3．4∶1时,二氧化硫和氯化氢的排放达标,脱硫效率和脱氯效率分别为75％和94％;在试验中, 烟气中NOx排放、烟气中汞含量和二恶英类排放都不超标;试验产生的飞灰含碳量低,飞灰中痕量元素的浸出毒性不超标;计算表明,如果利用余热干燥污泥和预热空气可有效地减少辅助燃料的消耗量。     

200MW锅炉煤/煤气混烧检测试验研究

在一台200MW锅炉上开展了五种不同煤/煤气掺配比例工况的试验研究,采用便携式可视化系统检测并分析了掺烧不同比例与不同发热量的煤气对炉膛温度、火焰黑度、主蒸汽参数与锅炉效率的影响。结果表明:(1)炉膛温度随掺烧高炉煤气量增加而下降,随焦炉煤气量增加而增加;(2)燃烧器区域的火焰黑度随高炉煤气量增加而减小,随焦炉煤气量增加而增加;(3)锅炉热效率随高炉煤气量增大而下降,随焦炉煤气量增大而上升;(4)在180 MW负荷时,综合考虑锅炉安全性和经济性,掺烧20%的高炉煤气和10%的焦炉煤气是较佳的煤气掺烧比例。     

煤粉炉喷钙脱硫过程的总体模型与模拟

1前言我国燃煤中约有三分之一用于火力发电,减少火电厂SO。排放是治理酸雨和SO。污染的重中之重。炉内喷钙脱硫结合尾部增湿活化技术（LIFAC）因流程简单、投资省、运行费用低而且效率较高,特别适用于燃烧中、低硫煤锅炉的改造,是一种具有广泛应用前景的技术［1］本文?..     

劣质煤沸腾燃烧过程动力特性和双床并联运行沸腾炉提高燃烧效率的试验研究

本文介绍了双床并联运行工业沸腾炉的结构原则,根据热平衡对比试验表明:这种沸腾炉在燃用劣质燃料时和单床沸腾炉相比,可以提高热效率16.6％.对燃用宽筛分劣质煤和燃用窄筛分的飞灰的沸腾床的燃烧过程动力特性作了试验测定,并对其结果进行了分析.从而提出在设计和运行上应该注意的问题和双床沸腾炉能够提高热效率的原因.     

掺加粉煤灰提高含钙脱硫剂的烟气脱硫率的实验研究

一、前言 在我国降低SO_2的排放量,控制酸雨的形成和发展已刻不容缓。为了减少SO_2对大气的污染,应着重降低燃烧设备特别是电站煤粉燃烧设备的SO_2排放量。目前用以减少电站燃煤设备的SO_2排放量的方法主要有燃烧后烟气脱硫、流化床燃烧和炉内喷钙脱硫。烟气脱硫技术的设备投资昂贵,运行费用高,难以在我国广泛应用。流化床燃烧在相     

Effects of fly ash on NOx removal by pulsed streamers

NO_x removal methods using plasma chemical reactions in nonthermal plasmas have been widely studied. In this paper, the effects of the addition of fly ash on NO_x removal using short-pulsed discharge plasmas are described. Fly ash which had been collected from a coal-burning thermal electrical power plant was used. Experiments were performed using four different mixtures of gases which included NO. These were (N₂+NO), (N₂+NO+O₂), (N₂+NO+H₂O), and (N₂+NO+O₂+H ₂O). These gas mixtures were used either with or without the addition of fly ash. The initial concentration of NO was fixed at 200 ppm (NO parts per million of the gas mixture), The study of the NO_x (NO+NO₂) removal was performed with the fly ash, as it is relevant to real situations in coal power plants. The results show that the presence of fly ash decreased the NO_x removal rate slightly in the case of dry gas mixtures while it increased the NO_x removal rate substantially in the case of wet gas mixtures. These results suggest that the presence of fly ash in the flue gases, which also contain a few percentages of moisture, would be advantageous to the treatment of flue gases emitted from thermal power plants for the removal of nitrogen oxides     

Partitioning and transformation behavior of selenium during coal combustion

The partitioning of selenium in coal-fired flue gas and desulfurization wastewater is of great threat to the ecological environment and human health. However, the unclear understanding of interactions between selenium vapors and fly ash hinders the emission control of selenium from coal-fired power plants. To further illuminate the mechanism of selenium partitioning and transformation, this study carefully estimated selenium distribution characteristics in the coal combustion byproducts from several industrial power plants. The effective temperature range as well as the key ash components for selenium retention by fly ash was clarified by multiple-scale experiments and theoretical perspectives. The results showed that gaseous selenium tended to be captured by fly ash at a medium-to-low temperature range (i.e. below 650 °C). The limited residence time resulted in the incomplete capture of gaseous selenium by fly ash. Mullite, quartz, iron oxides, and anhydrite in fly ash were found to be the main trappers for gaseous selenium. Among these components, iron oxides showed excellent selenium adsorption performance at a wide temperature range of 150-700 °C, which was realized by the strong chemical adsorption. By contrast, as the dominant phases in fly ash for the physical adsorption of gaseous selenium, mullite and quartz mainly captured gaseous selenium below 300 °C. On the other hand, sulfur dioxides had priority over gaseous selenium to react with calcium-containing ash components by forming anhydrite in the high-temperature region. The formed anhydrite had a limited selenium adsorption capacity, which was confirmed to capture gaseous selenium through a combination of physical adsorption and weak chemical adsorption. For the in-depth control of selenium emitted into desulfurization system and atmosphere environment, these findings provided a comprehensive insight into the behavior of selenium partitioning and transformation into fly ash during coal combustion.     

Ash formation and deposition during combustion of pulverized torrefied wood and coal in a 100 kW downflow combustor

Torrefied wood originating from beetle-killed trees is an abundant biomass fuel that can be co-fired with coal for power generation. In this work, pulverized torrefied wood, a bituminous coal (Sufco coal) and their blended fuel with a mixing ratio of 50/50 wt.%, are burned in a 100-kW rated laboratory combustor under similar conditions. Ash aerosols in the flue gas and ash deposits on a temperature-controlled surface are sampled during combustion of the three fuels. Results show that ash formation and deposition for wood combustion are notably different from those for coal combustion, revealing different mechanisms. Compared to the coal, the low-ash torrefied wood produces low concentrations of fly ash in the flue gas but significantly increased yields (per input ash) of ash that has been vaporized. All the mineral elements including the semi- or non-volatile metals in the wood are found to be more readily partitioned into the PM₁₀ ash than those in the coal. The inside layer deposits sticking to the surface and the loosely bound outside deposits exposed to the gas both show a linear growth in weight during torrefied wood test. Unlike coal combustion, in which the concentration of (vaporized) ash PM₁ controls the inside deposition rate, wood combustion shows that the formation of porous bulky deposits by the condensed residual ash dominates the inside deposition process. Co-firing removes these differences between the wood and coal, making the blended fuel to have more similar fly ash characteristics and ash deposition behavior to those of the bituminous coal. In addition, results also show some beneficial effects of co-firing coal with torrefied wood, including reduction of the total deposition rate and the minimization of corrosive alkali species produced by wood.     

两级烟气废热溴化锂制冷机热能利用经济性分析

废热溴化锂制冷机可以直接利用烟气废热或化学反应热来驱动进行制冷,因此废热回收的综合利用率比较高。论文对烟气废热驱动废热溴化锂制冷机的热能利用的经济性进行了分析,在烟气废热驱动溴化锂制冷机中,溴化锂制冷机的COP仅仅反映的是溴化锂制冷机本身的性能,不能作为衡量废热溴化锂制冷机废热制冷的效率高低和性能好坏的标准,因此本文采用废热利用率和废热制冷率对烟气废热溴化锂制冷机的废热制冷性能指标,废热制冷率与炯效率分析结果相一致,通过比较发现,二级烟气双效废热驱动废热溴化锂制冷机的废热制冷率最高,炯效率也最高。     

An investigation of the effect of ultrasonic waves on the efficiency of silicon extraction from coal fly ash

Burning of coal accounts for an enormous proportion of the current energy supply, especially in developing countries. Burning of coal produces large amounts of coal fly ash, which causes serious environmental problems unless it is managed properly. Using chemical analysis, we found that coal fly ash could be a promising source of Si, Al, Ca and some rare earth elements, especially with the assistance of some measures such as ultrasound. In this study, we extracted silicon from coal fly ash using an alkaline dissolution strategy and investigated the effects of temperature and ultrasonic power on the efficiency of silicon extraction. During a 70 min reaction, the efficiency of silicon extraction increased markedly, from 9.41% to 34.96%, as the reaction temperature increased from 70 °C to 110 °C. With ultrasound assistance, ultrasonic waves enhanced the extraction of silicon at both 80 °C and 110 °C at 720 W ultrasound, increasing the efficiency of silicon extraction from 6.01% to 15.36% and from 34.96% to 54.42%, respectively. However, at 900 W ultrasonic power, extraction was slightly inhibited at both temperatures, causing a little decrease in efficiency.     

减少二氧化碳对LIBS检测飞灰中未燃碳含量影响的研究

通常热力发电厂将飞灰中未燃碳的含量作为评价锅炉燃烧效率的重要指标,通过测量飞灰中未燃碳的含量来评价煤粉燃烧的充分程度,进而实现优化燃烧、提高机组效率。基于激光诱导击穿光谱技术(LIBS)无接触、快速响应、高灵敏度、可以在线测量等特点,备用来测量飞灰中未燃碳的含量。由于烟气中CO₂气体的存在,碳谱线强度会随CO₂浓度的变化而改变。为了减少CO₂气体对飞灰未燃碳测量结果的影响,提出并设计了具有二级旋风分离器的LIBS测量飞灰未燃碳含量实验系统,飞灰从给粉机流出后通过二级旋风分离器进入测量腔体,脉冲激光经过透镜作用于飞灰样品进而产生等离子体。LIBS系统采用双中心波长光谱仪,可测得飞灰中C,Si,Mg,Fe,Ca和Al等主要元素谱线,同时高分辨率通道可分辨出相邻C和Fe的元素谱线,可以在获得充分的飞灰光谱信息的同时保证了测量的精度。实验结果表明该系统可有效分离和收集飞灰颗粒,减少CO₂气体对测量结果的干扰,为LIBS技术的工程应用提供了更准确的依据。     

Biomass fly ash deposition in an entrained flow reactor

Fly ash deposition on boiler surfaces is a major operational problem encountered in biomass-fired boilers. Understanding deposit formation, and developing modelling tools, will allow improvements in boiler efficiency and availability. In this study, deposit formation of a model biomass ash species (K₂Si₄O₉) on steel tubes, was investigated in a lab-scale Entrained Flow Reactor. K₂Si₄O₉ was injected into the reactor, to form deposits on an air-cooled probe, simulating deposit formation on superheater tubes in boilers. The influence of flue gas temperature (589 – 968°C), probe surface temperature (300 – 550°C), flue gas velocity (0.7 – 3.5?m/s), fly ash flux (10,000 – 40,000?g/m²h), and probe residence time (up to 60?min) was investigated. The results revealed that increasing flue gas temperature and probe surface temperature increased the sticking probability of the fly ash particles, thereby increasing the rate of deposit formation. However, increasing flue gas velocity resulted in a decrease in the deposit formation rate, due to increased particle rebound. Furthermore, the deposit formation rate increased with probe residence time and fly ash flux. Inertial impaction was the primary mechanism of deposit formation, forming deposits only on the upstream side of the steel tube. A mechanistic model was developed for predicting deposit formation in the reactor. Deposit formation by thermophoresis and inertial impaction was incorporated into the model, and the sticking probability of the ash particles was estimated by accounting for energy dissipation due to particle deformation. The model reasonably predicted the influence of flue gas temperature and fly ash flux on the deposit formation rate.     

The roles of added chlorine and sulfur on ash deposition mechanisms during solid fuel combustion

The focus of this paper is on effects of chlorine and sulfur on coal ash deposition rates, under practically relevant but systematically controlled combustion conditions. This problem is important, not so much for coal, but to understand and predict deposition rates for biomass combustion where chlorine contents can be high. To this end, ash deposition rates on a controlled temperature surface were measured for controlled amounts of chlorine and sulfur added to a pulverized coal, doped with potassium and burned in a 100 kW rated combustion rig. Previous work with 35 tests on 11 coal, biomass and petroleum coke fuels burned under a range of operating conditions had strongly suggested that the deposition rate of the tightly bound inside deposits was independent of the ash aerosol composition, and depended only on PM₁ in the flue gas. The loosely bound outside deposition rate was dependent primarily on the total alkali content in the flue gas. The new results using chlorine added to the fuel (in the form of ammonium chloride) required these previous conclusions to be drastically revised. They showed that chlorine, not alkali alone, had large effects on the deposition rate of the inside deposits, which now were orders of magnitude higher than without chlorine addition, and did not fit previous (multi-fuel) correlations with PM₁. Sulfur addition, together with chlorine, did not affect deposition rates much, although it did lower the chlorine content of the deposit. These results are interpreted in terms of the ash aerosol size segregated composition, which was also measured, and potential sulfation reactions within the deposit.