On-line real-time measurements at incineration plants: PAHs and a PCDD/F surrogate compound at stationary combustion conditions and during transient emission puffs

Laser mass spectrometry has been applied for on-line monitoring of traces of aromatic compounds from flue gas of incineration plants. The experiments have been carried out at two sampling sites in an industrial hazardous-waste incinerator. With laser mass spectrometry resonance-enhanced multiphoton ionization (REMPI) with time-of-flight mass spectrometry (TOFMS) (REMPI-TOFMS), using the group selective multi-component monitoring approach, aromatic compounds are selectively ionized from the complex flue-gas matrix. In this case, the result of an REMPI-TOFMS on-line measurement is a distinct pattern of aromatic compounds. These patterns are dependent on: (i) the point of measurement, (ii) the incineration plant, (iii) the temperature, and (iv) the fuel. This contribution focuses on the fuel dependence of the pattern. The most transient behavior can be observed when containers filled with hazardous waste are burnt, leading to puffs. Real-time monitoring results of puffs are given. Furthermore, as an approach towards on-line monitoring of the TEQ (PCDD/F toxicity equivalent), REMPI-TOFMS on-line analysis results of chlorobenzene are presented.     

Membrane introduction/laser photoionization time-of-flight mass spectrometry

Two-photon resonance enhanced multiphoton ionization (REMPI) has been shown to be a unique ionization method for mass spectrometry, exhibiting both high sensitivity and chemical selectivity. Because REMPI is a gas-phase method, its applications have been limited either to direct analysis of vapor phase samples, or in conjunction with an initial laser desorption or other vaporization step. We describe here for the first time a combination of membrane introduction mass spectrometry (MIMS) and REMPI with time-of-flight mass spectrometry (TOF-MS), which allows for the direct analysis of trace amounts of organic compounds in water samples. The objective of our research was the detection of very low levels of aromatic contaminants, particularly benzene, toluene, and xylene (BTX), in aqueous solutions without interference due to the water. We have measured limits of detection (LOD) for selected aromatics in water below 1 part-per-trillion with an averaging time of less than 10 s using a continuous sample flow.     

Identification of surrogate compounds for the emission of PCdd/F (I-TEQ value) and evaluation of their on-line real-time detectability in flue gases of waste incineration plants by REMPI-TOFMS mass spectrometry

Correlations between products of incomplete combustion (PIC), e.g., chloroaromatic compounds, can be used to characterise the emissions from combustion processes, like municipal or hazardous waste incineration. A possible application of such relationships may be the on-line real-time monitoring of a characteristic surrogate, e.g., with Resonance-Enhanced Multiphoton Ionization-Time-of-Flight Mass Spectrometry (REMPI-TOFMS). In this paper, we report the relationships of homologues and individual congeners of chlorinated benzenes (PCBz), dibenzo-p-dioxins (PCDD), dibenzofurans (PCDF) and phenols (PCPh) to the International Toxicity Equivalent (I-TEQ) of the PCDD/F (I-TEQ value) in the flue gas and stack gas of a 22 MW hazardous waste incinerator (HWI). As the REMPI detection sensitivity is decreasing with the increase of the degree of chlorination, this study focuses on the lower chlorinated species of the compounds mentioned above. Lower chlorinated species, e.g., chlorobenzene (MCBz), 1,4-dichlorobenzene, 2,4,6-trichlorodibenzofuran or 2,4-dichlorophenol, were identified as I-TEQ surrogates in the flue gas. In contrast to the higher chlorinated phenols, the lower chlorinated phenols (degree of chlorination <4) were not reliable as surrogates in the stack gas. The identified surrogates are evaluated in terms of their detectability by REMPI-TOFMS laser mass spectrometry. The outcome is that MCBz is the best suited surrogate for (indirect) on-line measuring of the I-TEQ value in the flue gas by REMPI-TOFMS. The correlation coefficient r of the MCBz concentration to the I-TEQ in the flue gas was 0.85.     

基于关联模型的二恶英在线检测研究

为实现二恶英快速检测,指导废物焚烧炉二恶英减排,通过检测生活垃圾焚烧炉烟气中氯苯和二恶英浓度,研究了三氯苯、四氯苯和二恶英之间的关联关系,并利用实验室自行研制的飞行时间质谱仪对烟气样品的三氯苯进行在线检测。结果表明,三氯苯与二恶英毒性当量(I-TEQ)之间存在良好关联性,相关系数(R2)可达到0.89。仪器检测信号强度与三氯苯浓度之间具有良好的线性关系,根据在线检测烟气样品中三氯苯的信号可得到三氯苯浓度,并根据关联模型计算得到二恶英毒性当量值I-TEQ,实现了对烟气样品中二恶英的快速间接测量。     

Aerosol laser ablation mass spectrometry of suspended powders from PM sources and its implications to receptor modeling

Primary sources of particulate matter (PM) were analyzed by suspending powdered samples into an aerosol laser ablation mass spectrometer (LAMS). PM sources studied included vehicle exhaust particulates, dust from a non-ferrous smelter, cement powder, incinerator fly ash, two coal fly ash samples, and two soils. Marker peaks signified certain PM source sectors: construction particles could be distinguished by abundant Ca and Ca compounds, fuel combustion was marked by elemental carbon clusters, and nonferrous industrial particles showed inorganic As, Cu, Pb, Zn, and SOx. In addition to the distinction between particles from these different source sectors, mass spectral results also showed that for a single source, different particle types existed, and among different sources within a sector, similar spectra were present. The aerosol LAMS results show the difficulty in differentiating among separate fly ash sources as well as among different soil samples. A particle class balance receptor model that measures the amount of specific particle types rather than the amount of a chemical component is suggested as a means of source apportionment when particle spectra with overlapping source possibilities occur. The assumptions and limitations of receptor modeling aerosol LAMS data are also described. In particular, methods need to be developed to account for the contribution of secondary sources.     

Influence of combustion conditions on the PCDD/F-, PCB-, PCBz- and PAH-concentrations in the post-combustion chamber of a waste incineration pilot plant

Experiments at a pilot scale waste incinerator (0.5 MW thermal power) showed that the conditions in the post-combustion chamber (650-900 degrees C) are strongly influencing the formation of chlorinated and non-chlorinated aromatics. Non-optimal combustion conditions resulted in increased concentrations of mono- to trichlorinated dibenzo-p-dioxins (PCDD), dibenzofurans (PCDF) and polycyclic aromatic hydrocarbons (PAH), while chlorinated benzenes (PCBz), polychlorinated biphenyls (PCB) and the higher chlorinated PCDD/F are only weakly affected or even decrease. The changes in concentration of the compounds investigated over a time span of hours gave hints on 'memory effects' in this combustion zone. For mono- and dichlorinated benzenes, a high correlation (r2 = 0.80) with the international toxicity equivalent (I-TEQ) value of PCDD/F was observed. As recently has been demonstrated, this correlation can be utilized for an indirect on-line measurement of the I-TEQ by a novel laser mass spectrometric technique (REMPI-TO-FMS).     

Congener-specific detection of dioxins using jet-REMPI

Although 210 chemically different polychlorinated dibenzo-p-dioxin and dibenzofuran congeners can be produced during combustion, it is currently believed that fewer than 20 are toxic enough to warrant monitoring. SRI is developing a continuous emissions monitor to study the emission levels of these most toxic dioxins, leading eventually to an improved understanding of the formation of these molecules and to improved means of monitoring and control. We report here the first results of performing congener-specific detection for two dichloro dibenzo-p-dioxins present in low ppt concentrations in a mixture using the supersonic jet/resonantly enhanced multiphoton ionization time-of-flight mass spectrometer technique. In addition, we present preliminary data on the detection of chlorinated aromatic compounds using a two-color REMPI scheme with the same instrument.     

Performance evaluation of laser-induced breakdown spectrometry as a multimetal continuous emission monitor

Laser-induced breakdown spectroscopy (LIBS) has been evaluated as a multimetal continuous emissions monitor (CEM) at the U.S. Environmental Protection Agency (EPA) rotary kiln incinerator simulator (RKIS) facility in Raleigh, NC. Two detection systems with a bifurcated optical fiber bundle were used for simultaneously monitoring the concentrations of Be, Cd, Cr, and Hg in the test. Two calibration techniques were evaluated in the laboratory for the field measurements. On-line calibration of relative metal concentration was also performed in the simulated incinerator gas stream. Toxic metal concentrations measured with LIBS have been compared with the EPA reference method (RM) results.     

Transient puffs of trace organic emissions from a batch-fed waste propellant incinerator

Emissions data have been obtained from a waste propellant incinerator. The incinerator is a dual fixed hearth, controlled air incinerator equipped with acid gas and particulate scrubbing. "Puffing" has been evident in this waste propellant incinerator by spikes in the CO concentration. Transient puffs of organics may travel down the combustion chambers and lead to stack emissions. The major conclusions from this study are that (1) transient puffs are formed due to the semi-batch feed nature of the combustion process (causing a local oxygen deficiency) and high water content of the desensitized propellant; (2) in batch-fed combustors, puffs can contribute to most of the organic emissions (which are relatively low) measured with US EPA sampling and analytical methods; (3) it is estimated that batch-fed combustion contributes up to 7-18 times more emissions than steady-state combustion will generate; (4) by applying dispersion analyses to determine the amount of oxygen deficiency in the flame zone, the combustion zone concentration of CO during batch-fed operation could be as high as 160,000 ppm, compared to a measured peak stack concentration of 1200 ppm CO; and (5) an organic sample is collected and averaged over at least a 2-h period that smooths out the transient peaks of organics emissions during batch-fed operation. For emissions that are associated with long-term potential health impacts, this is an appropriate sampling method. However, if a compound has a short-term potential health impact, it may be important to measure the time-resolved emissions of the compound.     

A study into the parameters affecting selected reaction monitoring of 2,3,7,8-TCDD

The use of high resolution (10,000 resolving power) coupled gas chromatography - mass spectrometry is a well established technique in the analysis of polychlorinated dibenzo-p-dioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs) but in the case of heavily contaminated stack samples interferences can still occur. A complementary technique that offers high specificity is selected reaction monitoring (SRM).A study has been made into the effects that affect the metastable dissociation of 2,3,7,8-TCDD in the first field free region (FFR1) of a magnetic sector mass spectrometer, and monitored using SRM.Monatomic, diatomic and polyatomic gases have been investigated in the collision chamber of the mass spectrometer, as have the effects of electron energy, source temperature and trap current on the dissociation, and optima conditions determined for them.     

Particulate PAHs observed in the surrounding of a municipal incinerator

An intensive sampling campaign was undertaken in the surroundings of a municipal waste incinerator located in a French great urban centre in order to evaluate the impact of particles emissions on the ambient air and to estimate the exposure levels to toxic or carcinogenic compounds for a population living in the neighbourhood of this incinerator. To minimise the effect of industrial and road activities, sampling was performed during the 2 days of a weekend and on Monday morning. Different operating modes of the incinerator were investigated: (i) normal incinerator functioning and (ii) maintenance activity of the combustion chamber corresponding to the stop and cooling furnace periods. Particulate polycyclic aromatic hydrocarbons (PAHs) and total particulate carbon concentrations were determined in three sites situated, respectively, close to the incinerator, 2 km downwind and 1 km upwind of the plant. In normal operating mode similar concentrations were observed in the three sites. During the furnace stop an increase of total PAH concentrations was observed in the sampling site close to the incinerator. The concentration was 3 times higher than those measured in the other two sampling sites. But this increase was limited in time and in space since this phenomenon is only observed in the vicinity of the incinerator. The study of PAH profiles indicated that Pyrene and Retene showed the highest enhancement of their relative concentrations. The influence of incinerator functioning parameters on the PAHs concentrations is discussed. The furnace temperature and the mode of exhaust fumes seem to be deciding parameters to explain the increase of PAH level in the incinerator site. However, the incinerator emissions remained a minor part of the atmospheric pollution in the urban area.     

垃圾焚烧炉二次配风优化数值模拟

针对城市生活垃圾焚烧发电的排放问题,以重庆市某垃圾焚烧炉为原始模型,在炉膛两侧炉壁的适当位置设置二次配风口,并采用CFD（计算流体动力学）方法对炉膛内气体的二次燃烧过程进行数值模拟。通过观察对比有无二次配风以及二次配风口位置不同时炉膛内气体的温度场、气体在炉膛内的停留时间分布以及炉膛内气体的混合程度和湍动能等,重点分析了二次风在气体燃烧过程中所起的作用,并对2种不同二次配风口位置时抑制二恶英产生的效果进行了评价。通过对垃圾焚烧炉二次风的优化数值模拟,获得了适合本焚烧炉的比较合理的二次配风条件,可为焚烧炉的设计和改进提供一些有价值的参考。     

Optimisation and use of tandem-in-time mass spectrometry in comparison with immunoassay and HRGC/HRMS for PCDD/F screening

Rapid screening of polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans using quadrupole ion storage tandem-in-time mass spectrometry (QISTMS) conjointly with polyclonal antibody immunoassay has been considered. The optimisation of the fragmentation of the parent ion in the trap has been completed. The analysis of fly ashes from a municipal waste incinerator contaminated at different levels has then been realised. Results obtained using QISTMS, HRMS and immunoassay are compared.     

Beech foliage as a bioindicator of pollution near a waste incinerator

Since 1971 unshaded leaves from the top of marked beech trees (Fagus sylvatica L.) in the vicinity of a regional waste incinerator have been sampled every year in early September. The unwashed leaf samples were analyzed for the concentration of Cl- and, in some years, for 16 other elements. The operation of the waste incinerator distinctly increased the Cl- concentration in the foliage. When the flue gas filtration did not work properly, several other elements also accumulated (without any obvious dust accumulation). There were no significant correlations between precipitation and concentration of water-soluble elements in foliage samples. This suggested that precipitation was not accelerating foliar leaching so that the bioindication of pollutant accumulation is not restricted in foliage with a well developed cuticula.     

Characterization of biomass pyrolysis vapors with molecular beam, single photon ionization time-of-flight mass spectrometry

A single photon ionization, molecular beam sampling, reflectron time-of-flight mass spectrometer (SPI/MBTOFMS) has been developed and used to study pyrolysis products from a selection of biomass materials. Spectra are characterized by high resolution and decreased fragmentation compared to electron-impact ionization mass spectra from related molecular beam mass spectrometer systems equipped with quadrupole mass analyzers.     

新型转式垃圾焚烧过程中脱氯脱硫机理的研究

为了探讨有机垃圾焚烧过程钙基添加剂对HCl,SO_x生成特性的影响,分别在自行设计的中空水冷转式垃圾焚烧炉和固定床加热炉中进行了一系列的实验,研究结果表明新型转式焚烧炉具有强化传热传质特性,能提高HCl、SO_x的脱除率,可抑制有害气体的生成;同时也研究了 HCl,SO₂气体同时存在时,钙基添加剂对脱氯脱硫效率的影响规律。     

Simultaneous sampling of PCDD/PCDF inside the combustion chamber and on four boiler levels of a waste incineration plant

At a MSWI (municipal solid waste incinerator) plant PCDD/PCDF samples (gasphase and particulates) were taken simultaneously be a shock-freezing method in the incinerator combustion chamber at approx. 800°C and in four sampling sections in the boiler at about 490°C, 370°C, 330°C and 270°C. In this way PCDD/PCDF-formation in the flow through the boiler was determined. Two data sets were evaluated. A considerable PCDD/PCDF-formation had occurred already at boiler temperatures of about 490°C; the highest concentration, however, was found at the end of the boiler at about 300°C. The accompanying measuring program of plant parameters made the calculation of the PCDD/PCDF mass flows possible, which allowed the inclusion of the PCDD/PCDF-content in the ESP dust in the mass flow calculations.     

An incinerator air quality impact assessment for metals, PAH, dioxins and furans by using the MM5-CMAQ-EMIMO atmospheric modelling system: Spain case study

In this paper, we show the implementation of a modified version of MM5-CMAQ for carrying out an air quality impact analysis for installing an incinerator in the Basque Country model domain (Spain). The modified CMAQ model (EPA USA, 2004) includes Poly-Chlorinated Dibenzop-Dioxins and Dibenzo-Furans (dioxins and furans). This model represents their congeners as divided between gaseous and aerosol forms that exchange mass based on theoretical coefficients for gas to particle portioning. The emission model EMIMO – developed by UPM – has been adapted to incorporate the three metals and the benzo(a)pyrene according to the EMEP annual emission inventory. In addition, the PCDD/F EMEP emission inventory has been incorporated into the EMIMO model to produce proper 1 hr and 1 km × 1 km emission PCDD/F estimation. The emissions of the projected incinerator are incorporated by using the chimney technical parameters and the limit emission values (worst-case scenario) prescribed in the Directive/2000/76/CE.     

Adsorption and thermal reactions of 1,2,3,4-tetrachlorodibenzo-p-dioxin on fly ash from a municipal incinerator

Adsorption and thermal reactions of 1,2,3,4-tetrachlorodibenzo-p-dioxin (TCDD) on fly ash from a municipal incinerator were determined for temperatures between 100 to 300°C in air and in helium atmospheres. Results show 1,2,3,4-TCDD undergoes partial irreversable adsorption or decomposition in air at these temperatures. However, no decomposition products in air atmosphere were detected using gas chromatographic/mass spectrometric analysis of fly ash extracts and effluent.     

150t/d循环流化床生活垃圾焚烧炉的工艺结构与污染排放

垃圾焚烧处理技术在我国的应用越来越广泛 ,单纯引进国外的垃圾焚烧处理技术已经无法满足我国经济发展的需要。清华大学自主开发研制的 15 0t/d循环流化床生活垃圾焚烧炉已经通过专家鉴定 ,各项焚烧污染物排放指标均达到或优于国家标准 ,总体水平居国内领先水平。本文详细介绍了该焚烧炉的系统及结构 ,并对有关控制污染物排放的技术手段进行了详细分析