Vitrification of electric arc furnace dusts

Electric arc furnace baghouse dust (EAFD), a waste by-product of the steelmaking process, contains the elements that are volatilized from the charge during the melting (Cr, Pb, Zn, Cu and Cd). The results of leaching tests show that the concentration of these elements exceeds the regulatory limits. Consequently, EAFD cannot be disposed of in ordinary landfill sites without stabilization of the heavy metals. In this work, the vitrification of EAFD, from both carbon and stainless steel productions, were studied. The vitrification process was selected as the inertizing process because it permits the immobilization of the hazardous elements in the glass network and represents an environmentally acceptable method for the stabilization of this waste. Classes of various compositions were obtained by mixing EAFD with glass cullet and sand. The EAFD and the glass products were characterized by DTA, TG, X-ray analysis and by the TCLP test. The results show that the stability of the product is influenced by the glass structure, which mainly depends on the Si/O ratio. Secondary crystallization heat-treatment were carried out on some samples. The results highlighted the formation of spinel phases, which reduced the chemical durability in acid media. The possibility to recover Zn from carbon steel production EAFD was investigated and about 60-70% of metal recovery was obtained. The resulting glass show higher chemical stability than glasses obtained without metal recovery.     

国内电炉钢发展现状与应用前景

通过电炉铜与转炉铜能耗对比,突显了电炉钢的节能与环保优势,同时介绍了国内外电炉钢应用现状。随着社会工业化的发展所带来的钢铁积蓄量的增加,以及电炉钢技术的不断完善和发展,加之迎合国家低碳经济政策的实施,国内电炉钢发展具有广阔前景。     

Simulation of co-incineration of sewage sludge with municipal solid waste in a grate furnace incinerator

Incineration is one of the most important methods in the resource recovery disposal of sewage sludge. The combustion characteristics of sewage sludge and an increasing number of municipal solid waste (MSW) incineration plants provide the possibility of co-incineration of sludge with MSW. Computational fluid dynamics (CFD) analysis was used to verify the feasibility of co-incineration of sludge with MSW, and predict the effect of co-incineration. In this study, wet sludge and semi-dried sludge were separately blended with MSW as mixed fuels, which were at a co-incineration ratios of 5 wt.% (wet basis, the same below), 10 wt.%, 15 wt.%, 20 wt.% and 25 wt.%. The result indicates that co-incineration of 10 wt.% wet sludge with MSW can ensure the furnace temperature, the residence time and other vital items in allowable level, while 20 wt.% of semi-dried sludge can reach the same standards. With lower moisture content and higher low heating value (LHV), semi-dried sludge can be more appropriate in co-incineration with MSW in a grate furnace incinerator.     

Characteristics of gas and residues produced from electric arc pyrolysis of waste lubricating oil

An attempted has been made to recover high-calorific fuel gas and useful carbonaceous residue by the electric arc pyrolysis of waste lubricating oil. The characteristics of gas and residues produced from electric arc pyrolysis of waste lubricating oil were investigated in this study. The produced gas was mainly composed of hydrogen (35–40%), acetylene (13–20%), ethylene (3–4%) and other hydrocarbons, whereas the concentration of CO was very low. Calorific values of gas ranged from 11,000 to 13,000 kcal kg^?1 and the concentrations of toxic gases, such as NO_x, HCl and HF, were below the regulatory emissions limit. Gas chromatography–mass spectrometry (GC/MS) analysis of liquid-phase residues showed that high molecular-weight hydrocarbons in waste lubricating oil were pyrolyzed into low molecular-weight hydrocarbons and hydrogen. Dehydrogenation was found to be the main pyrolysis mechanism due to the high reaction temperature induced by electric arc. The average particle size of soot as carbonaceous residue was about 10 μm. The carbon content and heavy metals in soot were above 60% and below 0.01 ppm, respectively. The utilization of soot as industrial material resources such as carbon black seems to be feasible after refining and grinding.     

电场烟气流速过高对电除尘器的影响及其解决办法

论述了电场烟气流速过高对电除尘器的影响,并从电除尘器电场断面加高或加宽、降低排烟温度、电袋复合式除尘器三个方面分析了改造方案及典型工程的应用实例.阐述了具体工况下选择不同的解决办法来降低电场烟气流速,提高除尘效率.     

固态反应法制备FeHY催化剂及其催化降解活性艳蓝的性能研究

分别以NaY、NH4Y和HY沸石为载体,以乙酰丙酮铁为铁源,采用固态反应法制备了铁负载量均为10%（w）的FeNaY-10、FeNH4Y-10和FeHY-10催化剂。考察了各催化剂对活性艳蓝（KN-R）的降解效果,其中FeHY-10的催化降解效果最佳。采用XRD和FTIR技术对FeHY-10催化剂进行表征。表征结果显示,FeHY催化剂晶体结构仍然保持了Y分子筛特有的孔道结构,铁物种在Y 分子筛表面高度分散。催化降解实验表明,催化降解KN-R的最佳工艺条件为KN-R溶液（质量浓度为300 mg/L）加入量为50 mL、溶液pH为2、催化剂FeHY-25（铁负载量为25%（w））加入量为0.281 3 g、H2O2质量浓度为6.356 g/L、降解温度为35 ℃、降解时间为140 min,在此工艺条件下FeHY催化剂对KN-R的降解率为97.4%。     

Gasification applicability study of polyurethane solid refuse fuel fabricated from electric waste by measuring syngas and nitrogenous pollutant gases

To recycle polyurethane foam waste generated from electric appliance recycling centers for use as fuel in a gasification process, polyurethane solid refuse fuel fabricated as pellets was analyzed for the characteristics of elemental composition, proximate analysis, heating value, and thermo-gravimetric testing. It has a high heating value of 29.06 MJ/kg with a high content of combustibles, which could be feasibly used in any thermal process. However, the nitrogen content, of up to 7 %, was comparably higher than for other fuels such as coal, biomass, and refuse-derived fuel, and may result in the emission of nitrogenous pollutant gases of HCN and NH₃. By conducting gasification experiments on polyurethane solid refuse fuel in a fixed-bed reactor, a syngas with a heating value of 9.76 kJ/m³ and high content of both H₂ and CO were produced with good gasification efficiency; carbon conversion 54 %, and cold gas efficiency 60 %. The nitrogenous pollutant gases in syngas were measured at the concentrations of 160 ppm hydrogen cyanide and 40 ppm ammonia, which may have to be reduced using proper cleaning technologies prior to the commercialization of gasification technology for polyurethane waste.     

微纳米气泡耦合FexS催化氧化去除烟气中NO

采用固体废物锍铁化合物（记为Fe_xS）作为催化剂,耦合微纳米气泡催化氧化去除烟气中NO,考察了不同工艺条件下的去除效果,运用XRD、SEM和EDS技术对反应前后的Fe_xS进行了表征,探究了反应机理。实验结果表明,在Fe_xS粒径为0.038~0.053 mm、Fe_xS投加量为5 g、NaCl质量浓度为0.3 g/L、溶液pH为5、进气NO质量浓度为6.7 mg/L的最佳工艺条件下,NO去除率高达95.3%。表征结果显示,反应后的Fe_xS较反应前没有明显的物相变化,Fe_xS表面的微量物质催化了NO的氧化去除。     

次氯酸钾氧化去除烟气中单质汞的反应机理

采用KClO氧化吸收烟气中的Hg⁰,研究了脱汞性能和反应机理。结果表明：提高反应温度会降低脱汞性能,加快KClO热分解,减小Hg⁰溶解度,抑制氧化还原放热反应;提高Hg⁰浓度会增大Hg⁰在气相主体和气液界面的分压差,进而提高Hg⁰的传质速率,使Hg⁰去除率提高;继续提高Hg⁰浓度,反应限速步骤从气膜移向液膜,使Hg⁰去除率下降;KClO质量分数低于10%时,Hg⁰和KClO溶液的气液两相传质效率由液相控制;Hg⁰去除率随吸收液初始pH的升高而降低,吸收液pH随反应时间的延长而升高。     

臭氧氧化—钙法吸收工艺对烟气的同步脱硫脱硝

针对中国石化镇海炼化乙烯动力锅炉烟气的特点,进行烟气模拟,采用臭氧氧化—钙法吸收同时脱硫脱硝工艺处理模拟烟气。实验对比了单独脱硫和脱硝过程与同时脱硫脱硝工艺的脱硫、脱硝效果,探究了烟气在反应器中的停留时间、臭氧投加量和烟气含氧量对SO₂去除率和NO_x去除率的影响。实验结果表明：SO₂和NO的共存可促进污染物的去除;烟气停留时间延长,SO₂去除率提高,NO_x去除率先升高后降低;臭氧与NO摩尔比增加,NO_x去除率提高,SO₂去除率略有降低。综合考虑选择烟气停留时间3.4 s,烟气含氧量12%（φ）,臭氧与NO摩尔比0.7,在此工艺条件下反应70 min,NO_x去除率为73.8%,SO₂去除率为74.1%。     

The municipal solid waste system and solid waste characterization at the municipality of Veles, Macedonia

A short-term study to characterize the solid waste stream in the Municipality of Veles, Macedonia, was performed during a 1 week period in the summer of 2002. In this study, several important parameters of the municipal solid waste stream were assessed. It was estimated that the average daily generation rate is 1.06+/-0.56 kg/cap/day, while the specific weights of the uncompacted and compacted solid waste are approximately 140.5 kg/m3 and 223 kg/m3, respectively. Furthermore, it was estimated that the daily generated volume of uncompacted waste is 7.5+/-4 L/cap/day. Although the short-term study is characterized by numerous limitations, in the absence of other existing data, such a study with direct measurements could significantly contribute to the development of an efficient solid waste management system in countries with economies in transition like Macedonia.     

高活性自由基在烟气脱硫脱硝中的应用

从高活性自由基强氧化性的新视角,分析了几种基于不同自由基反应的燃煤电厂烟气脱硫、脱硝工艺,详细介绍了它们的反应机理、研究现状、应用以及最新进展,并分析了这些技术的优缺点,最后对其发展前景作了展望。     

活性焦烟气脱汞的试验研究与数值模拟

采用固定床吸附系统,对自制褐煤活性焦的脱汞性能进行了试验研究,研究发现自制活性焦对烟气中Hg0有一定的吸附能力,随着Hg0的入口浓度的增加,活性焦质量的增加,活性焦的吸附量也在增加。40mg时3号活性焦由10ng/min汞入1：2浓度时26．68％的最大吸附效率提高到40ng／min汞入口浓度时的53．12％。10ng/min汞入口浓度时3号活性焦在40mg时的最大吸附效率为26．68％,而在80mg时吸附效率提高到43．2％。烟气中的SO2、NO气体对活性焦吸附汞有一定的促进作用。在试验的基础上建立了固定床吸附系统的数学模型,基于Lan—mguir吸附系数,考虑吸附过程中颗粒内、外的传质控制过程,建立质量平衡方程。通过Matlab模型计算,计算结果与试验结果基本吻合,计算的活性焦脱汞效率要优于试验数值,计算的是理想情况下活性焦对汞的吸附效率,实际情况会有所降低。     

NaClO2湿法烟气脱硫脱硝技术研究

介绍了NaClO2溶液湿法烟气脱硫脱硝技术的主要特点、反应机理、工艺流程，分析了NaClO2溶液湿法烟气脱硫脱硝技术的主要影响因素，并提出了该技术今后的研究方向。     

平板陶瓷膜回收烟气水热的实验研究

将平板陶瓷膜组成膜组件对烟气水分和余热进行回收,考察了烟气的温度、相对湿度、流速和冷却水温度等参数对膜组件水热回收性能的影响。在实验工况下,水通量和水回收效率随着烟气温度、烟气相对湿度的增加和冷却水温度的降低而上升;水通量随着烟气流速的加快而上升,水回收效率随着烟气流速的加快先上升后降低;膜组件的水通量和水回收效率最高分别可达22.0 kg/(m²·h)和36.3%。平板陶瓷膜回收的热量主要来自烟气潜热,烟气潜热换热量与水通量呈正相关变化趋势。在实验工况下,平板陶瓷膜组件的总传热系数最高为412 W/(m²·℃),高于多通道管式陶瓷膜和单通道管式陶瓷膜。     

Monitoring of odor compounds produced by solid waste treatment plants with diffusive samplers

Nuisance caused by odors is one of the most important problems for waste management plants. To control an odor nuisance, it must first be quantified. The analytical difficulties in odor measurements are related to the high number of volatile components (belonging to several chemical classes), above all when the concentration is lower than the detection limit of the technique used for the measurement. In this work, 2-butanone, alpha-pinene, tetrachloroethylene, dimethyldisulfide, beta-pinene, limonene, phenol and benzoic acid are determined, because they are representative of some important classes of compounds with higher odor impact. The compounds are sampled with thermal desorbable radial diffusive samplers Radiello containing Tenax cartridges. The analytical repeatability and the complete thermal desorption of the cartridges were verified for each odor compound; the relative standard deviations for repeated samples and the recovery percentage were, respectively, less than 7% and about 97% for all compounds. The measurements of the linearity of sampling showed no systematic difference according to the collection period. The comparison between the odor threshold and the limit of detection demonstrated that this method is reliable for the recognition and quantification of odor compounds, allowing Public Administration to impose legal limits and the control agencies to verify them.     

Verification of exponential distribution of arrival and service times at municipal solid waste facilities

Vehicle queuing at municipal solid waste (MSW) facilities causes economic and environmental damage. In the United States, typical MSW receiving facilities (transfer, recycling, energy recovery, and landfill) have three queues: one at the entrance weighing station, one at the waste tipping location, and one at the exit weighing station. A common method of determining queue behavior relies on equations that assume exponentially distributed arrival and service times, but there has not been a comprehensive study to determine whether this assumption is valid for a variety of MSW facilities and conditions. In this study, data were gathered from two transfer stations, two energy recovery plants, and one transfer/landfill facility. Among the five facilities there was a variety of queuing styles. The data were plotted as an inverse exponential relationship and linearized. The linearized plots were regressed and R ² values were calculated. It was determined that the negative exponential relationship can be used to describe arrival times at all three queues and service times at weighing queues. The queuing equations are therefore theoretically supported for use at entering and exiting weighing queues and moderately theoretically supported for use at tipping queues.     

火电厂燃煤烟气过氧化氢脱硝技术的研究及应用

H2O2脱硝工艺是面向火电厂烟气污染物控制的一种环境友好型控制技术。通过对H2O2脱硝反应机理、关键影响因素、工艺路线和经济性等方面研究,综述了国内外H2O2脱硝技术研究进展,分析了不同工艺中存在的问题,并针对存在的问题进行了探讨。     

Effect of chlorine on volatilization of Na, K, Pb, and Zn compounds from municipal solid waste during gasification and melting in a shaft-type furnace

In the present work, a shaft-type furnace model in which the furnace column is divided into multiple cells was proposed and equilibrium reaction calculation software was used to describe the model. The model was used to study the effects of gasification and melting conditions such as temperature, oxygen partial pressure, and chlorine content on the volatilization behaviors of the low-boiling-point metals Na, K, Pb, and Zn during the gasification and melting process of municipal solid waste in a shaft-type furnace. Consequently, the volatilization ratios of Na, K, Pb, and Zn compounds in the exhaust gas from a pilot plant shaft-type furnace were found to be in good agreement with the calculation results, and the Na, K, Pb, and Zn compounds were volatilized mainly as metal chlorides in the temperature range up to approximately 1173 K. With a further rise in temperature, these low-boiling point metals were volatilized as metallic forms. It was found that almost 100% of Pb and Zn compounds were volatilized regardless of the chlorine content in municipal solid waste; in contrast, the volatilization rates of Na and K increased when the chlorine content increased. Finally, Na, K, Pb, and Zn compounds were converted from reduced metals to metal chlorides such as NaCl, KCl, PbCl₂, and ZnCl₂ with an increase in the ratio of chlorine to each metal.