烧结过程中解耦燃烧与烟气返回共脱硝新工艺Ⅱ:模拟燃烧带的脱硝机理

通过模拟烧结过程中焦炭的分布,研究了返回烟气、热解气主要组分与焦炭耦合燃烧降低NO,排放的规律.结果表明,热解气主要组分与焦炭耦合燃烧可使NO,排放降低10%左右,烟气返回到焦炭燃烧过程可使Nox的排放降低15%.耦合燃烧和烟气返回结合可使Nox的排放降低20%以上,在新工艺过程中,焦炭层厚度由150mm增大到300mm时,Nox排放的降低率由23%增大到40%.烧结过程解耦耦合燃烧与烟气返回脱硝工艺可有效减少Nox的排放.     

中高温区碳酰肼还原NOx和抑制二{（左）口（右）恶}英的研究

济大学热能与环境工程研究所,上海 200092;2.上海宝钢研究院,上海 201900;3.上海电站辅机厂,上海 200090）摘要：试验研究了氧量为10.1%～16.7%的条件下,中高温区（450～1050℃）碳酰肼还原烟气中NO_x,及以不同方式加入焚烧炉和烧结系统时抑制二{（左）口（右）恶}英的生成.结果表明,在烟气中氧量较高的条件下,碳酰肼在600℃和967℃左右,脱硝效率分别达到最大,850℃左右时最低,显示了双峰效应.将碳酰肼溶液喷入适当温度区域的烟气中,能明显降低二{（左）口（右）恶}英在再合成温区（250～450℃）收集的飞灰中的二{（左）口（右）恶}英含量;将碳酰肼混入烧结矿料中进行烧结锅试验,烧结烟气中的二{（左）口（右）恶}英排放含量随着碳酰肼掺混量的增大而降低;当碳酰肼的掺混量（质量分数）达到0.1%时,烟气中二{（左）口（右）恶}英的毒性当量浓度与不掺时相比降低了78.8%.研究表明碳酰肼可以多种方式加入焚烧炉和烧结炉中抑制NO_x和二{（左）口（右）恶}英的排放,是一种很有前景的NO_x和二{（左）口（右）恶}英双效抑制剂.     

SCR装置对焦炉煤气燃烧废气中PCDD/Fs、PCBs和PCNs的协同脱除

研究了某大型焦化厂的选择性催化还原(SCR)装置对焦炉煤气燃烧废气中典型非故意产生持久性有机污染物(UPPOPs)的脱除效果,对SCR装置入口和出口废气和SCR装置降尘中二英(PCDD/Fs)、多氯联苯(PCBs)和多氯萘(PCNs)的全部异构体进行了分析.结果表明,SCR装置对总PCDD/Fs的脱除效率最高,为94.6%,对总PCBs和总PCNs的脱除率分别为74.7%和78.4%.SCR装置入口和出口废气中UP-POPs同系物的分布模式明显不同,入口处以高氯取代为主,出口处以低氯取代为主.SCR装置对高氯取代UP-POPs有更好的脱除效果.催化还原和催化氧化降解同时发生是SCR装置脱除废气中UP-POPs的重要机制.     

The ignored emission of volatile organic compounds from iron ore sinter process

Iron ore sintering is a major source of gaseous and particulate pollutants emission in iron smelt plant. The aim of present study is to characterize the volatile organic compounds(VOCs) emission profiles from iron ore sintering process. Both sinter pot test and sinter simulation experiment were conducted and compared. Out results showed that sinter process produced large quantity of VOCs together with NOxand SO_2. VOCs and NO were produced simultaneously in sinter pot test from 3 to 24 min after ignition, flowed by SO_2 production from 15 min to the end of sintering. Total VOCs(TVOC) concentration in sinter flue gas was affected by the coal and coke ratio in sinter raw material. The maximum TVOC concentration was 34.5 ppm when using 100% coal as fuel. Sinter simulation experiments found that the number of VOCs species and their concentrations were found by sinter temperature. The largest VOCs species varieties were obtained at 500 °C. Benzene, toluene,xylene and ethylbenzene were major VOCs in sinter flue gas based on the results from both simulation test and sinter pot. It thus demonstrated that in addition to NO_x, SO_2 and metal oxide particles, sinter flue gas also contained significant amount of VOCs whose environmental impact cannot be ignored. Based on our work, it is timely needed to establish a new VOC emission standard for sinter flue gas and develop advanced techniques to simultaneously eliminate multi-pollutants in iron ore sinter process.     

Effect of temperature and oxygen on the formation of chlorobenzene as the indicator of PCDD/Fs

Sampling and analysis of polychlorinated dibenzo-p-dioxins and dibenzofurans(PCDD/Fs) are both time-consuming and expensive. In principle,real-time monitoring of chlorobenzene(CBz) as an indicator for PCDD/Fs could be useful to control and optimize incinerator operating conditions.To test this strategy,CBz was analyzed together with PCDD/Fs in flue gas samples collected from a hospital waste incinerator.Moreover,lab experiments were conducted to investigate the eect of temperature and oxygen on CBz formation from fly ash from the same incinerator.The experimental results demonstrate that chlorobenzene(in particular PeCBz) correlate well with PCDD/Fs,in line with previous research.The optimum temperature of CBz formation is in a range of 350 to 400°C and CBz yield increases significantly with oxygen,in line with PCDD/Fs formation.This study is useful for confirming the de novo mechanism and defining correlations between CBz and PCDD/Fs.     

干法水泥回转窑共处置滴滴涕废物的示范工程

利用新型干法悬浮预热预分解回转窑对滴滴涕废物进行共处置研究.滴滴涕废物以1t/h的投加速率,从窑尾烟室加入窑系统,比较了未处置废物工况和处置滴滴涕废物工况下烟气、生料、熟料、飞灰中滴滴涕和二 浓度.结果表明:在投加滴滴涕废物工况下,滴滴涕得到有效分解,其销毁率和销毁去除率分别为99.99953%和99.999982%;在处置滴滴涕废物前后烟气二 浓度没有发生明显变化,其浓度排放远低于水泥窑废物处置要求低于0.1ng-ITEQ/Nm3的水平;该水泥生产工艺系统在处置滴滴涕废物时,二 烟气排放因子为0.0396μg/t熟料,熟料排放因子为0.220μg/t;滴滴涕废物处置对炉窑生产,运行工况参数和常规污染排放没有显著影响.     

燃料特性对铁矿石烧结及烟气排放的影响

采用烧结杯试验,从固体燃烧角度出发,探究燃料结构和粒度对燃烧前锋温度及烧结气氛变化的影响。结果表明:随着燃料中煤粉比例逐渐提高(0~100%),烧结速度提高至4.32 mm/min,利用系数提高至0.13 t/(m2·h);转鼓强度先上升后下降,当煤粉比例为25%时,转鼓指数达到最高(58.4%);烟气中NO_x浓度与CO成分分别提高28.34 mg/m3和0.72%,CO能促进NO的还原反应,抑制NO_x生成。全煤条件下,随着煤粉粒径<1 mm的质量分数由50%降低到10%,烟气中NO_x降低了51.33 mg/m3,提高燃料粒度可降低烟气NO_x排放浓度;而延长烧结时间,NO_x总排放量上升。研究结果可为烧结燃料选择及烟气减排提供参考。     

基于污泥掺烧的某生活垃圾焚烧厂烟道气、飞灰及炉渣中的二(口恶)英特征

以我国南方某生活垃圾焚烧厂掺烧10%市政污泥的生活垃圾为研究对象,对前/后口废气、飞灰、炉渣及用于掺烧的污泥中17种二(口恶)英的含量进行了测定,并分析了其指纹分布特征.结合焚烧工况及处理设施,从生成机理角度探讨了二(口恶)英的排放特征、毒性当量浓度主成分特征及主要单体的排放因子线性关系.结果表明：掺烧10%的市政污泥后,废气中二(口恶)英的去除率为99.4%,低于国家排放标准;固体废物中二(口恶)英含量为飞灰 > 炉渣 > 污泥.这说明采用高温焚烧和"活性炭喷射+布袋除尘"装置不会影响掺烧10%污泥的达标排放.指纹分布特征表明,前口废气以1,2,3,4,6,7,8-HpCDF和OCDD为主,后口废气以OCDD和OCDF为主;飞灰、炉渣及污泥中的主要单体为OCDD、1,2,3,4,6,7,8-HpCDD、OCDF、1,2,3,4,6,7,8-HpCDF.主成分分析显示,前口废气和飞灰中的二(口恶)英毒性分布特征相似;炉渣和污泥的毒性分布特征相似;后口废气有自身的特征.这说明在相同工况条件下,经同一设施处理的废物中二(口恶)英排放特征相似.排放因子分析表明,2,3,4,7,8-PeCDF和1,2,3,6,7,8-HxCDF、1,2,3,6,7,8-HxCDD和1,2,3,7,8,9-HxCDD与总毒性排放因子具有较强的线性关系,且呋喃类（PCDFs）强于二(口恶)英类（PCDDs）.     

深圳市废弃物焚烧炉飞灰中二噁英含量水平和特征分析

采用同位素稀释的高分辨气相色谱/高分辨磁式质谱联用仪(HRGC/HRMS)对深圳市8所垃圾焚烧厂飞灰中二噁英进行准确定量检测,分析比较不同炉型、不同种类废弃物焚烧厂飞灰中的二噁英浓度水平和分布情况.结果发现8所废弃物焚烧炉飞灰中二噁英浓度差异较大,5所往复炉排生活垃圾焚烧炉样品中二噁英的质量浓度和TEQ浓度平均值都小于热解型医疗垃圾焚烧炉.两所不同的工业危险废物焚烧炉中,以烧废物矿油的立式筒焚烧炉的二噁英含量远大于以焚烧电路板为主的回转窑焚烧炉.不同焚烧炉飞灰中二噁英异构体的浓度分布具有相类似的特征,高氯代二噁英的含量明显高于低氯代二噁英同系物.不同的PCDD/Fs单体对I-TEQ的贡献率在不同的焚烧设备中十分相似,2,3,4,7,8-Pe CDF、1,2,3,7,8-Pe CDD、2,3,4,6,7,8-Hx CDF 3种单体是TEQ浓度的主要贡献单体.在布袋除尘器前喷淋活性炭能有效吸附烟气中二噁英,将其转移到飞灰中.本研究是首次针对深圳市运行中的废弃物焚烧炉进行飞灰中二噁英排放分析,为二噁英排放监控提供重要的基础数据.     

遗体火化二(口恶)英类排放水平及影响因素

采用现场监测方式调查了国内13台火化机烟气中PCDD/Fs排放情况,分析火化炉型、烟气处理设施和随葬品等因素对其排放水平的影响,提出相关污染控制措施和管理措施的建议. 结果表明,各样品的PCDD/Fs毒性当量浓度(以I-TEQ计,下同)差异较大,范围为0.027~15.8 ng·m^-3,平均值为3.2 ng·m^-3. PCDD/Fs排放因子范围为45.9~22236 ng·具^-1,均值为4738 ng·具^-1. 平板炉PCDD/Fs排放水平总体低于捡灰炉,达标率高于捡灰炉. 火化烟气中17种PCDD/Fs异构体分布特征存在一定差异. 部分火化机PCDD/Fs排放浓度仍处于较高水平,有必要从源头上减少污染、提高污染控制技术、加强政府监管,如将随葬品另炉火化、增设二燃室、配备布袋除尘器和活性炭喷射处理设施等.     

《火葬场大气污染物排放标准》实施对火化炉烟气二噁英减排的影响

为调查殡葬行业大气污染物排放新标准《火葬场大气污染物排放标准》(GB 13801—2015)实施4年后火化烟气中二英(PCDD/Fs)的污染排放特征及其对行业的影响,在我国南方地区选取了32台火化炉,对其排放烟气中PCDD/Fs水平、影响因素、排放因子进行了研究,并评估标准实施4年后的效果. 结果表明:①火化烟气PCDD/Fs毒性当量浓度(以I-TEQ计,下同)为0.033~7.4 ng/m3,平均值为1.1 ng/m3,PCDD/Fs超标率为56.2%,其中拣灰炉和平板炉超标率分别为62.5%和50.0%. 与GB 13801—2015实施前相比,火化炉废气中PCDD/Fs排放浓度显著下降,说明PCDD/Fs污染减排成效明显,但排放水平和超标率仍较高. ②有无废气处理工艺、运行管理水平、随葬品数量与PCDD/Fs排放浓度密切相关. 废气处理设施缺失或无法正常运行时PCDD/Fs毒性当量浓度为0.32~7.4 ng/m3,平均值为2.5 ng/m3,超标率达75.0%;配备“活性炭吸附(ACI)+布袋除尘(BF)”工艺且运行正常时,PCDD/Fs毒性当量浓度范围为0.033~4.5 ng/m3,平均值为0.83 ng/m3,超标率为58.3%,可能与部分处理设施使用率低、运行不佳和维护不到位等原因有关. 指纹特征显示,无废气处理工艺时七氯代、八氯代同系物占比较高;配备“ACI+BF”处理设施时以四氯代、五氯代同系物为主,证实该工艺组合主要去除高氯代同系物. ③火化炉废气PCDD/Fs排放因子(以I-TEQ计,下同)为67.8~39 981 ng/具,平均值为4 217 ng/具,显著低于联合国环境规划署(UNEP)于2005年发布的第1和第2级排放因子(分别为90和10 μg/具),但高于其优化控制措施的排放因子(0.4 μg/具). 研究显示,未来需加强对我国遗体火化PCDD/Fs减排的技术帮扶及排放因子的更新.      

医疗废物焚烧炉周边环境介质中二噁英的浓度、同系物分布与来源分析

采用高分辨气相色谱/高分辨质谱仪(HRGC/HRMS)测定了我国西北某医疗废物焚烧炉排放烟气及周边环境空气、土壤和植物样品中2,3,7,8-PCDD/Fs含量和组成,并对周边环境中二噁英来源进行了初步解析.监测结果表明烟气中二噁英毒性当量浓度(以I-TEQ计)均值为184 ng·m-3,远超医疗废物焚烧废气排放标准限值(0.5 ng·m-3),环境空气、土壤和植物样本中二噁英毒性当量浓度均值分别为7.30 pg·m-3、52.5 pg·g-1、146 pg·g-1,均处于较高的污染水平.污染源下风向上的环境空气样品中二噁英浓度明显高于上风向上样品中的浓度,下风向样品中的浓度随与污染源距离的增加呈现先升高后降低的趋势,最高浓度的样本距污染源700 m左右.烟气样品2,3,7,8-PCDD/Fs同类物单体质量浓度(毒性当量)分布特征与主导风下方向空气、土壤、植物样本中的具有较强的相似性.样本二噁英浓度空间分布特征、同类物分布特征及主成分分析数据均表明,该区域环境中二噁英主要来源于医疗废物焚烧烟气排放.     

医疗废物焚烧厂周边环境空气中二英浓度分布及其健康风险评估

于2015-2018年冬季（12月-2月）对广东省某医疗废物焚烧厂排放烟气及焚烧设施周边2.5 km范围内6个采样点分别进行了4次烟气和环境空气样品采集,应用高分辨气相色谱/高分辨质谱（HRGC-HRMS）联用技术对二（口恶）英（PCDD/Fs）浓度水平进行监测并对其组成特征进行了分析,运用主成分分析法（PCA）对周边环境空气中二（口恶）英来源进行了初步解析,同时采用VLIER-HUMAAN模型评估其对人体的健康风险.结果表明该医疗废物焚烧厂烟气二（口恶）英毒性当量浓度为0.542~21.300 ng·Nm^-3（以I-TEQ计）,排放水平较高;周边环境空气中PCDD/Fs质量浓度和毒性当量浓度变化范围分别为0.682~196.000 pg·m^-3和0.036~17.700 pg·m^-3（以I-TEQ计）,周边环境空气中PCDD/Fs浓度明显受到排放源烟气落地点的影响.空气样品中二（口恶）英同族体及异构体分布指纹谱图与该焚烧设施排放烟气类似,空气质量浓度主要贡献单体以OCDD、1,2,3,4,6,7,8-HpCDF、OCDF以及1,2,3,4,6,7,8-HpCDD为主,主要毒性贡献单体为2,3,4,7,8-PeCDF.PCA源解析结论与指纹谱图特征分析结论基本一致,该研究区域中环境空气二（口恶）英主要来源于医疗废物焚烧烟气排放.健康风险评估结果表明,该区域人群呼吸暴露风险总体处于较为安全的水平（0.0032~0.141 pg TEQ·kg^-1·d^-1）,部分个体的呼吸暴露贡献率超过了评价限值,应引起重视.     

焦炉烟气中二（口恶）英类物质排放水平研究

二噁英和类二噁英多氯联苯属于《关于持久性有机污染物的斯德哥尔摩公约》规定的非故意产生的持久性有机物,统称为二噁英类物质.焦化生产过程中具备二噁英类物质生成所需的前体物、温度、催化剂等条件,但目前国内外对焦化行业焦炉烟气二噁英类物质排放研究仍属空白,为进一步明确焦化行业排放水平和影响因素,针对性地提出行业减排和控制措施,利用高分辨气相色谱-高分辨质谱法对4个不同规模的典型焦化企业焦炉烟气中二噁英类物质排放情况进行现场采样和实验室分析.结果表明,二噁英类物质毒性当量(以WHO-TEQ计)范围为3.9~30.0 pg·m-3,处于较低水平,检出较多的PCDD/Fs同系物主要是高氯代的.另外,烟气中此类物质的排放量与焦化生产工艺关系密切,捣鼓炼焦、较高的炭化室高度有利于减少二噁英类物质的排放.     

Mercury mass flow in iron and steel production process and its implications for mercury emission control

The iron and steel production process is one of the predominant anthropogenic sources of atmospheric mercury emissions worldwide. In this study, field tests were conducted to study mercury emission characteristics and mass flows at two iron and steel plants in China. It was found that low-sulfur flue gas from sintering machines could contribute up to41% of the total atmospheric mercury emissions, and desulfurization devices could remarkably help reduce the emissions. Coal gas burning accounted for 17%–49% of the total mercury emissions, and therefore the mercury control of coal gas burning, specifically for the power plant burning coal gas to generate electricity, was significantly important. The emissions from limestone and dolomite production and electric furnaces can contribute29.3% and 4.2% of the total mercury emissions from iron and steel production. More attention should be paid to mercury emissions from these two processes. Blast furnace dust accounted for 27%–36% of the total mercury output for the whole iron and steel production process. The recycling of blast furnace dust could greatly increase the atmospheric mercury emissions and should not be conducted. The mercury emission factors for the coke oven,sintering machine and blast furnace were 0.039–0.047 g Hg/ton steel, and for the electric furnace it was 0.021 g Hg/ton steel. The predominant emission species was oxidized mercury, accounting for 59%–73% of total mercury emissions to air.     

Removal of PCDD/Fs and PCBs from flue gas using a pilot gas cleaning system

A 100 Nm3 /hr capacity pilot scale dual bag filter (DBF) system was tested on the flue gas from an actual hazardous waste incinerator (HWI), the removal efficiency of polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans (PCDD/Fs) and polychlorinated biphenyls (PCBs) was also studied. The first filter collected most of the fly ash and associated chlorinated organic; then activated carbon (AC) was injected and used to collect phase chlorinated organic from the gas. Concentrations of PCDD/Fs and PCBs after the DBF system were 0.07 and 0.01 ng TEQ/Nm3 , respectively, which were both far below the national emission standard. Comparing with the original single bag filter system, the PCDD/Fs concentration dropped a lot from 0.36 to 0.07 ng TEQ/Nm3 . Increasing AC feeding rate enhanced their collection efficiency, yet reduced the AC utilization efficiency, and it still needs further study to select an appropriate feeding rate in the system. These results will be useful for industrial application and assist in controlling emissions of PCDD/Fs and other persistent organic pollutions from stationary sources in China.     

废物焚烧厂烟气中PCDD/Fs和PCNs的排放特征

采用同位素内标稀释高分辨气质联用分析法,对废物焚烧厂的烟气样品PCDD/Fs和PCNs进行了测定,分析了其排放特征以及相关性,为有组织排放的PCDD/Fs和PCNs的控制提供理论依据.实验结果表明,空白实验中未发现明显的背景干扰;样品中PCDD/Fs的采样内标回收率范围为74.0%~90.1%,提取内标的回收率范围为53.3%~120.0%,均符合US EPA23和CHN HJ77.2-2008的质量控制标准;PCDD/Fs的同系物浓度均随着氯取代数目的增加而增加,而PCNs同系物则随着氯取代数目的增加表现出先增大后减小的规律.同系物之间的皮尔森相关系数分析结果可知,这两类污染物相邻同系物相关性系数明显大于非相邻同系物相关性系数,表明低氯代同系物可能是生成高氯代同系物的一个重要途径.此外,PCNs和PCDD/Fs同系物的线性相关分析结果表明,一些PCNs化合物（PeCN、HxCN、HpCN、OCN）与某些PCDD/Fs（OCDD、PeCDF、HxCDF、HpCDF）具有良好的相关性（R²=0.55~0.78）,由此推断在废物焚烧过程中这些同系物可能具有相类似的生成机制.     

氧化铜催化五氯苯生成二英的研究

研究在加热条件下,五氯苯在CuO表面催化生成二英（PCDD/Fs）的过程.结果表明,在200～350℃,PCDD/Fs的生成量随温度的升高而增加;在350～450℃,PCDD/Fs的生成量随温度的升高而减少.温度较低时（200～250℃）,生成的PCDD/Fs以高氯取代同系物为主;温度较高时（400～450℃）,则以低氯取代的同系物为主.但温度的改变并没有引起同一氯取代度PCDD/Fs中的异构体分布模式发生规律性变化.通过比较400℃条件下CuO催化五氯苯生成PCDD/Fs与CuO催化OCDD/F的脱氯降解情况,推测了五氯苯生成PCDD/Fs的途径.低氯取代的PCDDs可能主要来源于五氯苯生成的高氯取代PCDDs的进一步脱氯降解.而PCDFs则主要由五氯苯脱氯降解生成的低氯取代产物直接缩合生成.     

几种可能来源对广东某地空气中二(口恶)英的影响

采用高分辨气相色谱法/高分辨质谱法（HRGC/HRMS）对广东某地生活垃圾焚烧厂烟道气及周边环境空气和可能来源的环境空气中17种二英进行了分析.讨论了所有样品中同系物、主要毒性贡献体的特性.并运用主成分和聚类分析法,探究了焚烧厂周边监测点位与焚烧厂排放烟气及可能来源的关系.结果表明周边空气中二英浓度低于焚烧厂烟道气,且不受主导风向的影响.在调查基础上,推断轮胎厂及露天焚烧为可能污染源.轮胎厂二英浓度均低于上风向监测点,露天焚烧空气中二英高于厂界外监测点.对各同类物百分比分析可知,烟道气和所有空气中主要同类物为OCDD、1,2,3,4,6,7,8-HpCDD及1,2,3,4,6,7,8-HpCDF,但空气中同类物还包括OCDF;焚烧厂周边监测点与轮胎厂空气中二英单体百分浓度相似,烟气与露天焚烧中二英单体分布相似.进一步研究表明所有空气样品中单体1,2,3,7,8-PeCDD和2,3,4,6,7,8-HxCDF与总毒性当量浓度的线性相关系数分别为0.95和0.75,相关性较强.主成分分析及聚类分析表明垃圾焚烧厂对周边空气产生影响,轮胎厂对上风向产生影响,露天焚烧对厂界影响较小.     

Emission characteristics of dioxins, furans and polycyclic aromatic hydrocarbons during fluidized-bed combustion of sewage sludge

Pre-dried sewage sludge with high sulfur content was combusted in an electrically heated lab-scale fluidized-bed incinerator. The emission characteristics of polychlorinated dibenzo-p-dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs) and polycyclic aromatic hydrocarbons (PAHs) were studied. Coal and calcium oxide (CaO) were added during the sewage sludge combustion tests to optimize combustion conditions and control SO2 emission. The results indicated that the flue gases emitted during mono-combustion of sewage sludge were characterized by relatively high concentrations of SO2, NOx and organic pollutants, due to the high sulfur, nitrogen, and volatile matter content of sewage sludge. The total 16 USEPA priority PAHs and 2,3,7,8-substituted PCDD/Fs produced from sewage sludge combustion were found to be 106.14 g/m3 and 8955.93 pg/m3 in the flue gas, respectively. In the case of cocombustion with coal (msludge/mcoal = 1:1), the 16 PAHs and 2,3,7,8-substituted PCDD/Fs concentrations were markedly lower than those found during mono-combustion of sewage sludge. During co-combustion, a suppressant e ect of CaO on PCDD/Fs formation was observed.