生活垃圾与煤混合燃烧特性及动力学分析

利用热重分析仪对生活垃圾与煤混合试样的燃烧特性及热反应动力学进行了实验研究,考察了不同配比混合试样的着火温度、燃尽温度、最大燃烧速率及最大燃烧速率温度等燃烧特征参数,并用Coats-Redfern积分法对其进行了燃烧动力学分析,确定了燃烧动力学方程,求出了反应活化能Ea及指前因子A。实验结果表明:生活垃圾与煤混合燃烧时均保持各自的燃烧特性;混合燃料中随着生活垃圾掺量的增加,热重曲线向低温区转移,燃尽点逐渐降低,综合燃烧特性指数明显增大,生活垃圾能改善煤的燃烧性能;生活垃圾及其与煤混合燃烧出现两个燃烧阶段,分别遵循二级和一级反应机理,煤燃烧只出现一个燃烧阶段,遵循一级反应机理;混合燃料燃烧反应活化能Ea与指前因子A存在动力学补偿效应。     

不干胶废弃物热解焦燃烧特性

采用非等温热重分析和固定床热解实验研究了不干胶废弃物热解焦生成特性及热解焦燃烧特性,并计算了不同升温速率下热解焦的燃烧动力学参数。结果表明,不干胶废弃物热解焦产率随温度升高而逐渐降低,当热解终温在400~700℃时,热解焦产率在34.64%~22.03%之间;空气气氛下热解焦燃烧过程包括3个阶段:挥发分燃烧阶段(390~600℃)、混合燃烧阶段(390~600℃)和残炭燃烧与矿物分解阶段(650℃);升温速率对热解焦燃烧效果作用明显,升温速率越大,燃烧特性指数越高,燃烧稳定性越好;热解焦燃烧过程可以通过3个一级反应描述,当升温速率为40℃/min时热解焦燃烧各阶段表观活化能明显降低,表明升温速率提高有助于热解焦的燃烧反应活性,更有利于燃烧反应的进行。     

基于Fluent的整体式催化反应系统降解甲苯的数值模拟

为得到甲苯在整体式催化系统中的燃烧规律,利用Fluent 18.1对整体式催化反应系统中甲苯-空气在铂(Pt)上的燃烧特性进行了数值模拟。通过假设多孔介质内气固间局部能够达到热平衡,建立了三维的多孔介质催化燃烧模型。经验证,该模型能够很好地反映甲苯在整个系统中的燃烧特性。通过对整个反应系统中温度场、浓度场和速度场的工况探究和通过分段控制燃烧反应发现:贫燃条件有利于催化燃烧,富燃条件有利于引发热力燃烧;当量比小于1,入口流速小于2 m·s~(-1)时,有利于催化燃烧,催化转化率在96%以上;当量比较高,入口流速较大时,有利于引发热力燃烧。以上研究结果为该技术的实际应用提供了参考。     

城市污泥掺混水煤浆燃烧特性的热重分析

通过热重实验,分析了污泥、水煤浆的单一燃烧特性以及水煤浆中掺混不同质量比的城市污泥后混合浆的燃烧特性.结果表明,混合浆着火温度因污泥的掺入比水煤浆高约50 ℃,但随掺混比例的升高,最大燃烧速率、可燃性指数及综合燃烧特性指数均增加,且提高了污泥的燃尽率.混合浆热分析曲线出现两个挥发分析出燃烧峰(分别对应250～380、380～570 ℃)与1个固定碳燃烧峰(570～680 ℃),燃烧特性总体表现为污泥与水煤浆的共同作用,在某些方面优于污泥或水煤浆的单一燃烧.总之,利用湿污泥直接掺混水煤浆从燃烧性能来说是可行的.     

板材类生物质燃烧及动力学特性热重研究

采用非等温升温法研究了4种板材类生物质在空气气氛下的燃烧特性和动力学特性。通过对TG、DTG等曲线的分析,发现4种板材燃烧过程均可分成3个阶段,即水分蒸发阶段、挥发份析出(或燃烧)阶段和固定碳燃烧阶段。综合燃烧特性:松木集成材>纤维密度板>夹芯胶合板>刨花板。4种板材均具有良好的燃烧特性。4种生物质燃烧均存在1个吸热峰和2个放热峰,分别与挥发分析出峰、挥发分燃烧、固定碳燃烧对应。采用Fridman法和Fridman-Carroll法分别对4种板材的动力学参数进行了计算,2种方法得出的结果符合较好。分析得出:由于生物质燃烧与环境换热、挥发分析出吸热、固定碳燃烧放热等因素作用,4种生物质的表观活化能高温区均低于低温区。动力学计算结果表明:松木集成材平均表观活化能最低,燃烧反应能较容易进行。     

污水污泥在富氧环境下燃烧特性的实验研究

采用综合热分析仪研究了空气气氛和富氧气氛下污水污泥和煤的燃烧曲线,分析比较氧浓度对污泥燃烧特性参数的影响,并计算得到各工况下的动力学参数。结果表明：随着氧浓度增加,污泥燃烧DTG曲线向低温区移动,着火温度和燃尽温度均降低,综合燃烧指数大大提高,污泥燃烧特性得到改善。可用两段一级反应动力学模型来较好的描述污泥的主要燃烧过...     

半焦与城市污泥混合物的燃烧性能研究

采用热重分析法研究了半焦与城市污泥混合物的燃烧性能,揭示了半焦添加量对城市污泥燃烧性能的影响规律,为基于半焦的污泥调质与机械脱水污泥的高效能源化利用提供理论支持与依据。结果表明:城市污泥的着火温度低,容易燃烧,但其灰分高,燃烧速率慢,燃烧性能差;云南褐煤热解半焦的着火温度比城市污泥高,着火相对困难,但其燃烧速率快,燃烧性能好;随半焦配比的增大,半焦与城市污泥混合物的燃烧性能变好,说明半焦能改善城市污泥的燃烧性能,当半焦配比大于40%(质量分数)时,半焦与城市污泥混合物的微商热重曲线呈单峰,有较好的燃烧性能。     

包装垃圾添加脱氯半焦制备SRF的燃烧特性及动力学分析

利用热重分析仪对添加了不同比例混合含氯塑料经微波低温脱氯后的脱氯半焦制备而成的固体衍生燃料(SRF)的燃烧特性及热反应动力学进行了实验研究,考察了脱氯半焦不同添加比例制备的SRF的着火点、燃尽温度、最大燃烧速率、燃尽特征指数和综合燃烧指数等燃烧特征参数。并用Coats-Redfern积分法对其进行了燃烧动力学分析,确定了燃烧动力学方程,求出了反应活化能和指前因子。结果表明:随着脱氯半焦的添加比例从5%增加至20%,TG曲线向低温区移动,着火点降低,燃尽温度降低,燃尽性能提升,综合燃烧特性指数S均高于不添加脱氯半焦的燃料,综合燃烧性能更好;当脱氯半焦添加比例为10%,综合燃烧特征参数最佳;在第三燃烧阶段,添加了脱氯半焦的燃料的活化能显著低于未添加脱氯半焦的燃料,指前因子降低了4~5个数量级。混合含氯废塑料,经过微波低温脱氯处理形成半焦作为添加剂制备SRF,不仅降低了SRF燃烧过程中氯化氢的产生量,同时提高了燃料的燃烧性能,是含氯塑料废弃物利用的一种新的方向和途径。     

不同氧浓度下脱脂餐厨垃圾燃烧特性及动力学研究

利用热重分析法和Coats-Redfern积分法,对不同氧浓度下脱脂餐厨垃圾的燃烧特性进行研究,得到了各试样的着火温度、燃烬温度及综合燃烧特性指数,并通过燃烧动力学分析得到各试样的活化能。实验结果表明,燃烧温度从室温升至1 000℃时,脱脂餐厨垃圾燃烧过程可分为3个失重阶段:水分析出阶段、挥发分析出及燃烧阶段和固定碳燃烧阶段;随着氧浓度的升高,脱脂餐厨垃圾最大失重率以及燃烧特性指数等燃烧特性参数都有显著变化。根据Coats-Redfern积分法计算得低温和高温阶段的活化能分别为83.76~91.2 k J/mol和95.25~141.7 k J/mol。     

控制燃油锅炉运行中NOx生成的技术研究

分析燃油锅炉运行中NOx产生的机理,探讨影响其生成的因素,研究抑制其生成和排放的燃烧技术低氧燃烧、掺水燃烧、空气分级燃烧和废气循环燃烧等.结合实验研究结果,重点分析空气分级燃烧和废气循环燃烧对油燃烧中燃料氮转化和氮氧化物生成的影响,并介绍一种新型低氮氧化物排放的燃油技术--预蒸发燃烧技术.     

Atmospheric Emissions from Open Burning

Emission data have been derived from the simulated open burning of municipal refuse, landscape refuse, and automobile components. The data confirm that disposal of refuse by open, uncontrolled burning invariably leads to higher emissions than incineration and creates an unnecessary air pollution problem.     

Emissions from Burning Grass Stubble and Straw

The emissions from burning the residue following grass-seed harvest were determined by means of a combined laboratory-field study. Samples of the straw and stubble residue were burned in the laboratory burning tower at the University of California at Riverside. Complete analyses were determined for gaseous and particulate emissions for the important grass species from the Willamette Valley of Oregon. Particulate emissions averaged 15.6 lb/ton of fuel burned. Carbon monoxide averaged 101 lb/ton of fuel burned. Hydrocarbon emission averages, in pounds per ton of fuel burned, were 1.74 for saturates plus acetylene, 2.80 for defines, and 1.68 for ethylene. The NO_x emission, at the temperature peak during the burn, averaged 29.3 ppm. Field studies, conducted by personnel from Oregon State University, measured only particulate emissions, carbon dioxide, and temperature over the burn. The carbon dioxide values were found to be similar to those obtained on the burning table at UCR and it was therefore concluded that the other gaseous emissions were similar and could be used as reasonably accurate for emission inventories. The temperature values obtained in the laboratory and field were also similar and further justifies extrapolating the burning table data to field situations. The particulate matter collected in the field studies averaged 15.55 lb of particulate per ton of fuel burned. This is the same average obtained for the burning table data which again serves to validate the emissions reported from Riverside. Much more variability was found in the particulate emissions obtained in the field which reflects the wider range of environmental conditions encountered in the field.     

Burning Chemical Wastes as Fuels in Cement Kilns

Hazardous wastes in the environment represent one of our most serious problems. Ever increasing quantities of toxic wastes have contaminated our land, air, and water. Lack of adequate hazardous waste disposal facilities is a critical problem. Landfilling toxic wastes is no longer considered safe. The tragedy of the Love Canal has demonstrated the need for proper hazardous waste disposal facilities. The best organic chemical waste disposal method is process incineration. Cement kilns have been used for burning toxic chemical industrial wastes in Canada, Michigan, New York, Sweden, etc. Existing cement kilns, when properly operated, can destroy most organic chemical wastes. Even the most complex chlorinated hydrocarbons, including PCB can be completely destroyed during normal cement kiln operations, with minimal emissions to the environment. Burning toxic chemical wastes in cement kilns, and other mineral industries, is mutually beneficial to both industry, who generates such wastes, and to society and government, who want to dispose properly of such wastes in a safe, environmentally acceptable manner. The added benefit of energy conservation is important, since large quantities of valuable fuel can be saved in the manufacture of cement when such techniques are employed.     

A Study of Field Burning Under Varying Environmental Conditions

A field study on grass field burning was conducted in the Willamette Valley of Oregon during the summer of 1965. Approximately 230,000 acres of grass fields are burned in the valley during August and September. Serious air pollution problems result from this burning. The purposes of the study were to determine the effect of environmental variables on grass field burning and to determine if conditions exist when significant air pollution reduction can be achieved. The environmental variables investigated were time from harvest to burning, time of day, air temperature, relative humidity, soil and straw moisture, wind speed and direction, and fuel density. The dependent variables measured were particulate emission and size distribution, combustion temperature, burn rate, amount of ash, percent of organics in the particulate, and smoke appearance. The results were analyzed statistically to determine the significant variables and their relationship.     

Contribution of Burning of Agricultural Wastes to Photochemical Air Pollution

Agricultural wastes from orchards, grain fields, and range lands are burned each year in California as the most practical means of ridding the land of these wastes. In order to determine the relative contribution of the burning of such material to photochemical air pollution, the effluent from 1 23 fires of known weights of range brush, both dry and green, barley and rice stubble, and prunings from various fruit and nut trees were monitored in a special tower which provided an open burning situation. Analyses were made for total hydrocarbon, expressed as C, by flame ionization detection, and for 24 individual hydrocarbons by gas chromatography, as well as for CO and CO₂ by infrared spectroscopy. A few analyses were made for oxides of nitrogen. These data, coupled with temperature and airflow measurements, allowed calculations to be made on pounds of effluent per ton of material burned and demonstrated that the emissions from agricultural burning are much less than those from the automobile, a principal source of such emissions.     

The Release of Methyl Chloride from Biomass Burning in Australia

Abstract

Black carbon (BC) was measured every 5 min for two years (May 1998–May 2000) inside and immediately outside a northern Virginia house (suburban Washington, DC) occupied by two nonsmokers. Two aethalometers, which measure BC by optical transmission through a quartz fiber tape, were employed indoors and outdoors. Meteorological parameters were obtained on an hourly basis from nearby Dulles airport. Indoor activities were recorded to identify indoor sources such as combustion activities, which occurred 9% of the time during the first year and 4% of the time during the second year. At times without indoor sources, indoor/outdoor BC ratios averaged 0.53 in the first year and 0.35 in the second year.

The main outdoor source of BC was the general regional background, contributing 83–84% of the total during each of the two years. Morning rush hour traffic contributed 8–9% of the total BC. An evening peak in the fall and winter, thought to include contributions from wood burning, was responsible for ~8% of the annual average BC concentration. The main indoor sources of BC were cooking and candle burning, contributing 16 and 31%, respectively, of the annual average indoor concentrations in the two years. Relative humidity (RH) affected the outdoor aethalometer in both years. An artifact associated with the tape advance was noted for the aethalometer, but a correction factor was developed that reduced the associated error by a factor of 2.     

中小型燃煤炉烟气脱硫方法

对中小型燃煤炉烟气脱硫方法作了介绍,提出了对湿式除尘器(文丘里除尘器,旋风除尘洗涤塔,冲击式除尘脱硫塔等)的改造方法,以提高其烟气除尘脱硫效率。同时,介绍了干湿两级除尘脱硫系统和利用脱硫碱液及脱硫废水的烟气脱硫技术。