危险废物焚烧设施灰渣收集技术研究与实践

危险废物焚烧产生的飞灰具有重金属含量高、成分复杂的特点.现阶段主要采用机械输灰收集,机械输灰存在辅助设备多、劳动强度大、职业卫生隐患大等问题,难以实现自动化运行.故选取100 t/d典型工艺的焚烧设施,对4种机械输灰系统和4种气力输灰系统分别进行比较,发现小仓泵在职业卫生、能耗、输送效率、输送距离和输送方向等方面优势明显.通过对焚烧设施灰渣收集系统优化设计实践,可减少员工值守,避免职业卫生隐患,实现自动化运行,有利于完成集约化、高效化的示范项目考核.     

垃圾焚烧炉炉排国产化研制

宁波垃圾焚烧发电厂于2001年12月投入运行，配套的三台垃圾焚烧炉是从德国NOELL公司进口的炉排炉，每台焚烧炉有六种规格的炉排共2736片。由于炉排是易损件，每年都要有一定比例的更换。进口炉排备件不仅价格高，供货周期长，而且由于供货商情况的变化，今后难以保证提供炉排备件。为降低成本，确保炉排备件的供应，宁波枫林绿色能源开发有限公司和上海发电设备成套设计研究所合作，共同进行炉排国产化研制。     

垃圾焚烧炉中炉排系统的研究

以庆麦ＶＯＬＵＮＤ公司垃圾焚烧炉排系统为例，较详细地从原理，结构，材料和性能等方面介绍了当今世界最流行的机械往复炉排系统，并提出了炉排系统今后的改进要点和发展方向。     

生活垃圾协同焚烧污泥层燃燃烧特性研究

针对炉排炉焚烧生活垃圾及协同焚烧处置污泥(含水率40％、质量比例12％)的层燃燃烧过程,以及一次风风温对生活垃圾一污泥混合物料燃烧过程的影响开展模拟研究.结果 显示:协同焚烧污泥导致烟气温度在挥发分析出和燃烧阶段的前期上升、后期大幅下降,并导致炉膛的高温区域向炉排后段方向移动,最高温度降低,但对炉排上挥发物析出的时刻影...     

大型机械炉排炉膨胀补偿结构设计

介绍了大型机械炉排炉概况及技术风险,着重指出了热膨胀风险,给出了正常运行情况下的膨胀量计算方法,并提出了膨胀补偿解决方案;结合实际提出了一种适用于垃圾焚烧大型机械炉排的膨胀补偿结构,该结构在有效补偿整体结构的膨胀同时,还能防止膨胀缝的渗沥液渗漏,并配以风冷防止补偿结构的烧损,且安装简便,易于拆装。     

探讨高效能低排放生活垃圾焚烧炉的结构型式

国内生活垃圾焚烧厂大规模建设的同时也对焚烧厂各主要设备的效率以及污染物排放提出了更高要求。根据生活垃圾焚烧炉的特性,针对2种目前国内焚烧厂大量使用的炉排进行分析,从理论上解释如何通过炉排结构、炉拱形式及合理的配风来控制焚烧炉的污染物排放,并提出了焚烧炉在创新设计上实现高效能低排放的建议。     

我国生活垃圾焚烧发电厂的能效水平研究

采用欧盟垃圾焚烧发电厂能效计算方法和我国目前常用的能源计算方法,对生活垃圾焚烧发电厂的能效进行了计算。结果表明:目前我国生活垃圾焚烧发电厂项目能源利用水平比较低,项目能源利用率平均约为21%。对比炉排炉与流化床的吨垃圾净发电量与净上网电量,发现炉排炉的余热利用水平普遍高于流化床。不同地区、不同规模、不同炉型的垃圾焚烧发电厂,吨垃圾发电量存在明显差异。同时也表明,我国生活垃圾焚烧发电能效还有进一步的提升空间。     

郑州市生活垃圾处理的新模式探讨

通过分析郑州市生活垃圾处理现状和面临问题,借鉴国内外发达地区生活垃圾处理模式的发展历程,研究得出了郑州市应形成以"焚烧发电为主,卫生填埋为辅"的生活垃圾处理新模式,并适合采用机械炉排焚烧技术。     

几种垃圾焚烧炉及炉排的介绍

介绍了3种焚烧炉及4种典型的垃圾焚烧炉排，对焚烧炉的技术和经济投资进行了比较，说明机械炉排焚烧炉适合我国城市垃圾热值低、含水量高的特点，并提出垃圾焚烧发电产业化的设想。     

垃圾焚烧发电厂ACC与DCS关系探讨

结合上海康恒环境股份有限公司提供的三亚、珠海、哈尔滨、拉萨等多个项目,分析了ACC不纳入DCS、部分纳入DCS和全部纳入DCS控制方案的优缺点,提出在相对独立的炉排系统,现阶段最适宜的控制方案为部分纳入DCS的方式。     

Lipid peroxidation and oxidative status compared in workers at a bottom ash recovery plant and fly ash treatment plants

Fly ash and ambient emissions of municipal solid waste incinerators contain polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs), polycyclic aromatic hydrocarbons (PAHs), other organic compounds, metals, and gases. Hazardous substances such as PCDD/Fs, mercury vapors and other silicates, and the components of bottom ash and fly ash elevate the oxidative damage. We compared oxidative damage in workers exposed to hazardous substances at a bottom ash recovery plant and 3 fly ash treatment plants in Taiwan by measuring their levels of plasma malondialdehyde (MDA) and urine 8-hydroxydeoxyguanosine (8-OH-dG). Significantly higher MDA levels were found in fly ash treatment plant workers (3.20 microM) than in bottom ash plant workers (0.58 microM). There was a significant association between MDA levels in workers and their working environment, especially in the fly ash treatment plants. Levels of 8-OH-dG varied more widely in bottom ash workers than in fly ash workers. The association between occupational exposure and 8-OH-dG levels may be affected by the life style of the workers. Because more dioxins and metals may leach from fly ash than from bottom ash, fly ash treatment plant workers should, as much as possible, avoid exposing themselves to fly ash.     

城市生活垃圾焚烧灰渣的资源化利用

以国外城市生活垃圾焚烧灰渣资源化利用现状为基础，讨论了灰渣利用的主要途径：（1）石油沥青路面的替代骨料；（2）水泥或混凝土的替代骨料；（3）填埋场覆盖材料；（4）路堤、路基等的填充材料，已有的工程实践证明，只要控制处理得当，这些灰渣资料化利用可以不对人类健康和环境产生不利的影响，此外，也对灰渣资源化利用在环境标准和工程性质要求方面的规定及其采取的处理方法作了简单的分析。底灰经预处理后资源化利用，而飞灰经稳定化处理后填埋，是今后比较适合我国国情的灰渣管理策略。     

Leaching of polychlorinated dibenzo-p-dioxins and dibenzofurans in fly ash from municipal solid waste incinerators to a water system

In order to predict how much polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDDs/Fs) are leached from fly ash by rain water when fly ash is disposed, leaching of PCDDs/Fs from a fly ash obtained from a municipal solid waste incinerator (MSWI) was investigated by packing the ash in a column and eluting with water. In the beginning of the elution, PCDDs/Fs associated with water-soluble particulates in the ash were eluted, whereas in the latter half, those associated with water slightly soluble particles were eluted, judging from the comparison of PCDDs/Fs in eluate fractions with those transferred to solutions from the original ash by stepwise batch methods with water and 2N hydrochloric acid.The amounts of PCDDs/Fs eluted from the ash column were 2.9% and 1.7% of those extracted from the original ash, respectively, while large amounts of PCDDs/Fs were contained in the fly ash in the column after the elution, suggesting that PCDDs/Fs in water-insoluble particulates of the ash would not be eluted by water.     

生活垃圾焚烧飞灰固化处理的工程实践

以广州市李坑生活垃圾焚烧发电厂采用水泥固化工艺处理飞灰的工程实例,对固化前后的飞灰进行浸出毒性实验,同时采用不同配比的水泥进行固化工艺的条件实验.结果表明:飞灰原灰中的重金属浸出浓度超过我国危险废物鉴别标准,属于危险废物;当水泥的掺入比例为0.33时,飞灰的固化效果最佳.并结合飞灰的成分,建议对飞灰水泥固化体的长期安全性进行进一步研究.     

Comparative pulmonary fibrogenic potential of selected particles

The comparative intrapulmonary fibrogenic potential of a number of chemically and physically characterized ashes and dusts was studied. Sprague-Dawley rats were exposed through intratracheal instillation to 5, 15, or 45 mg of stack-collected coal fly ash, electrostatic precipitator hopper-collected coal fly ash, bag-house filter-collected coal-oil mixture fly ash, Dowson and Dobson quartz, heated montmorillonite clay, and Mt. St. Helens volcano ash. Following a 3-month postexposure period, the animals were killed and subjected to histological examination. Some fibrosis was produced by all the ashes. However, the effects differed both qualitatively and quantitatively among the various exposure groups. The most severe fibrosis was found in the quartz-treated animals, followed in order of intensity by the heated clay, volcano, ash, hopper coal ash, stack coal ash, and coal-oil mixture ash. No effects were found in the saline-exposed control rats.     

Lung clearance of neutron-activated Mount St. Helens volcanic ash in the rat

To determine pulmonary deposition and clearance of inhaled volcanic ash, rats received a single 60-min, nose-only exposure to neutron-activated ash. Over a period of 128 days after exposure, the rats were sacrificed in groups of five animals. Lungs were analyzed for the radionuclide tracers 46Sc, 59Fe, and 60Co by gamma-ray spectrometry. The alveolar ash burdens, determined by the radionuclides 46Sc and 59Fe, are in good agreement for the majority of samples analyzed, indicating ash particulate levels in the lungs, rather than leached radionuclides. The ash deposition estimates based on 60Co were appreciably lower for the lungs, indicating that 60Co leached from the ash. Approximately 110 micrograms ash, or 6% of the inhaled ash, was initially retained in the deep lung. The biological half-time of the alveolar ash burden was 39 days. After 90 days, the mean lung burden had decreased to about 20% of its initial value; 128 days after exposure, about 10% remained.     

Comparison of hemolytic activities of coal fly ash and its soluble and insoluble fractions

Coal fly ash of a particle diameter smaller than 10 micron was collected from the precipitator of a power plant in Hong Kong. Comparison of hemolytic activities between fly ash and free silica showed that fly ash had a lower biological effect than free silica. The hemolytic activities of the soluble and insoluble fractions of fly ash were further compared by two methods: total hemoglobin method and cyanmethemoglobin method. An analysis of results showed significant differences for fly ash and its soluble fraction between methods (P less than 0.05 and P less than 0.01, respectively). Fly ash, which contained a silicate level similar to its insoluble fraction, had a hemolytic activity higher than the summation of both its soluble and insoluble fractions. This indicates that the hemolytic activity was independent of the silicate content in the fly ash samples.     

Mount St. Helens' volcanic ash: hemolytic activity

Volcanic ash samples from four Mount St. Helens' volcanic eruptions were subjected to mineralogical, analytical, and hemolytic studies in order to evaluate their potential for cytotoxicity and fibrogenicity. Plagioclase minerals constituted the major component of the ash with free crystalline silica concentrations ranging from 1.5 to 7.2%. The in vitro hemolytic activity of the volcanic ash was compared to similar concentrations of cytotoxic and inert minerals. The ash was markedly hemolytic, exhibiting an activity similar to chrysotile asbestos, a known fibrogenic agent. The hemolysis of the different ash samples varied with particle size but not with crystalline silica concentration. The results of these studies taken in conjunction with the results of our animal studies indicate a fibrogenic potential of volcanic ash in heavily exposed humans.     

Surface reactivity of volcanic ash from the eruption of Soufrière Hills volcano,Montserrat, West Indies with implications for health hazards

The fine-grained character of volcanic ash generated in the long-lived eruption of the Soufrière Hills volcano, Montserrat, West Indies, raises the issue of its possible health hazards. Surface- and free-radical production has been closely linked to bioreactivity of dusts within the lung. In this study, electron paramagnetic resonance (EPR) techniques have been used, for the first time, on volcanic ash to measure the production of radicals from the surface of particles. Results show that concentrations of hydroxyl radicals (HO*) in respirable ash are two to three times higher than a toxic quartz standard. The dome-collapse ash contains cristobalite, a crystalline silica polymorph that may cause adverse health effects. EPR experiments indicate, however, that cristobalite in the ash does not contribute to HO* generation. Our results show that the main cause of reactivity is removable divalent iron (Fe2+), which is present in abundance on the surfaces of the particles and is very reactive in the lung. Our analyses show that fresh ash generates more HO* than weathered ash (which has undergone progressive oxidation and leaching of iron from exposed surfaces), an effect replicated experimentally by incubating fresh ash in dilute acid. HO* production experiments also indicate that iron-rich silicate minerals are responsible for surface reactivity in the Soufrière Hills ash.     

Bioavailability of 1-nitropyrene from model coal fly ash and its uptake by alveolar macrophages

Alveolar macrophage cultures exposed to coal fly ash vapor-coated with 1-nitropyrene were used as a model system to study the bioavailability and the uptake of a nitroaromatic hydrocarbon from coal combustion emissions. Initially, 1-nitropyrene-coated fly ash and uncoated fly ash were examined for cytotoxicity using rabbit alveolar macrophages and for mutagenicity in the Salmonella typhimurium plate incorporation assay. The results were compared to determine the effects of vapor deposition. The distribution and recovery of 1-nitropyrene from macrophage cultures treated with coated fly ash were determined by using a reverse-phase high-performance liquid chromatography-fluorescence method. 1-Nitropyrene alone was not very toxic, nor did vapor deposition of 1-nitropyrene onto coal fly ash significantly affect the toxicity of the fly ash. Most toxicity resulted from the original, uncoated fly ash particles. 1-Nitropyrene after being coated onto the particles was bioavailable in agar and aqueous culture medium. The coated fly ash showed mutagenic activity when the particles were tested directly; the uncoated fly ash did not show mutagenic activity. 1-Nitropyrene recovery from alveolar macrophage cultures exposed to the coated fly ash diminished as cell number increased. The rate of 1-nitropyrene loss was 2.7 ng/10(6) macrophages for medium and 4.1 ng/10(6) macrophages for the whole culture. The mutagenic activity recovered from these macrophage cultures also decreased with increasing cell number.