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污泥与煤在循环流化床混烧过程中的汞排放特性 总被引:1,自引:1,他引:1
在密相床截面积为0.23m×0.23m、高度为7 00m的循环流化床燃烧试验装置上进行了含汞污泥与煤的混烧试验.测试并分析讨论了污泥与煤混烧过程中汞的分布,探讨了Ca/S摩尔比、脱硫剂种类、过量空气系数等运行参数以及烟气成分对汞在烟气、飞灰和炉渣中形态分布的影响规律.结果表明,大部分汞进入烟气,且元素汞是混烧烟气中的主要存在形态.钙基脱硫剂对烟气中氧化态汞有较强的吸附脱除作用,CaO对汞的脱除效果要好于CaCO3.随着烟气中SO2、NOx浓度的增大,烟气中二价汞所占份额呈上升趋势.过量空气系数对烟气和灰渣中汞的浓度和形态分布有较大的影响. 相似文献
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XIE Jian-jun YANG Xue-min ZHANG Lei DING Tong-li SONG Wen-li LIN Wei-gang 《环境科学学报(英文版)》2007,19(1):109-116
This paper presents the experimental investigations of the emissions of SO2, NO and N2O in a bench scale circulating fluidized bed combustor for coal combustion and co-firing coal and biomass. The thermal capacity of the combustor is 30 kW. The setup is electrically heated during startup. The influence of the excess air, the degree of the air staging, the biomass share and the feeding position of the fuels on the emissions of SO2, NO and N2O were studied. The results showed that an increase in the biomass shares resulted in an increase of the CO concentration in the flue gas, probably due to the high volatile content of the biomass. In co-firing, the emission of SO2 increased with increasing biomass share slightly, however, non-linear increase relationship between SO2 emission and fuel sulfur content was observed. Air staging significantly decreased the NO emission without raising the SO2 level. Although the change of the fuel feeding position from riser to downer resulted in a decrease in the NO emission level, no obvious change was observed for the SO2 level. Taking the coal feeding position R as a reference, the relative NO emission could significantly decrease during co-firing coal and biomass when feeding fuel at position D and keeping the first stage stoichiometry greater than 0.95. The possible mechanisms of the sulfur and nitrogen chemistry at these conditions were discussed and the ways of simultaneous reduction of SO2, NO and N2O were proposed. 相似文献
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为了揭示生物质锅炉中活性分子臭氧脱硝的特点,在一台应用了活性分子臭氧深度一体化超低排放技术的生物质循环流化床锅炉上,开展烟气臭氧脱硝试验。采用烟气分析仪测量锅炉尾部烟道活性分子臭氧喷入前和塔顶烟囱处的烟气组分,重点探究了脱硝前后烟气污染物的排放特性以及臭氧投加量对脱硝效果的影响。结果表明:由于入炉生物质燃料的水分和热值的变化有较强的随机性,机组负荷及CO、NOx等污染物初始浓度均随之波动;烟气中NOx初始浓度的平均值为146 mg/m3,最高值可达480 mg/m3,其瞬时值与含氧量有着非常强的线性相关性,线性回归相关系数(R2)为0.96;随着臭氧投加量的增加,脱硝率从臭氧发生器功率为118 kW时的24%增至250 kW时的95%;应用活性分子臭氧脱硝技术后,臭氧发生器功率为250 kW时,烟气中NOx浓度一直稳定在15 mg/m3以下,满足超低排放标准要求。 相似文献
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对煤炭开采、运输和使用各个环节的环境污染和生态破坏外部成本进行核算的基础上,运用GREAT-E模型对煤炭环境成本内部化政策给GDP、居民收入、产业结构和贸易竞争力等带来的影响进行了定量分析.分析结果表明,煤炭开采、运输和使用各环节分别进行的环境成本内部化对中国宏观经济的影响较为有限,GDP的下降在可承受的范围之内,即使是全生命周期的煤炭环境成本完全内部化也只导致GDP出现0.15%左右的轻微下降.煤炭环境成本内部化将促进劳动力和资本等要素从高耗能行业向低耗能特别是技术密集型和现代服务业部门转移,进而推动产业结构优化转型升级.在煤炭生产、运输和消费环节通过征收环境相关税费能够更直接地刺激生产部门的环境行为调整,降低煤炭的生产和消费量,进而减少环境污染和生态破坏. 相似文献
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利用热重分析法对干污泥和煤及二者混合样的燃烧特性进行了研究.结果表明,在空气介质、升温速率25℃/min、温度范围20~1000℃的情况下,干污泥分别在280℃、480℃出现2个失重峰,煤在500℃时出现1个失重峰.随着干污泥掺烧比增加,混合样失重速率峰值及最大燃烧速率值增大,出现温度提前.一定比例范围的干污泥掺烧可以改善煤的着火性能,有利于煤的稳定燃烧,燃料的可燃烧性指数增加,使燃烧特性改善,该指数介于干污泥和煤单一成分燃烧特性指数之间. 相似文献
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Gang Zhang Jing Hai Jiang Cheng Zhiqi Cai Mingzhong Ren Sukun Zhang Jieru Zhang 《环境科学学报(英文版)》2013,25(1):231-235
The emission characteristics of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) and heavy metals were evaluated during co-combustion of sewage sludge with coal from a circulating fluidized bed incinerator. The stack gas, slag and fly ash samples were sampled and analyzed. The gas-cleaning system consisted of electrostatic precipitators and a semi-dry scrubber. Results showed that the stack gas and fly ash exhibited mean dioxin levels of 9.4 pg I-TEQ/Nm 3 and 11.65 pg I-TEQ/g, respectively, and showed great similarities in congener profiles. By contrast, the slag presented a mean dioxin level of 0.15 pg I-TEQ/g and a remarkable difference in congener profiles compared with those of the stack gas and fly ash. Co-combusting sewage sludge with coal was able to reduce PCDD/Fs emissions significantly in comparison with sewage sludge mono-combustion. The leaching levels of Hg, Pb, Cd, Ni, Cr, Cu, and As in the fly ash and slag were much lower than the limits of the environmental protection standard in China. These suggest that the co-combustion of sewage sludge and coal is an advisable treatment method from an environmental perspective. 相似文献
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IntroductionGranularfixedfiltershavebeenwidelyusedinindustryduetomanyoftheiradvantages,suchashighcollectionefficiency,wear,corrosionandheatresistanceandsoon (D’Ottavio ,1978) .However ,onedrawbackofgranularfixedfiltersisthattheycannotworkcontinuouslyforalong… 相似文献
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Nitrogen removal and simultaneous nitrification and denitrification in a fluidized bed step-feed process 总被引:2,自引:0,他引:2
For urban wastewater treatment, we conducted a novel four-stage step-feed wastewater treatment system combined with a fluidized bed laboratory experiment to investigate chemical oxygen demand (COD), NH4+-N, and total nitrogen (TN) removal performance. The removal rates of COD, NH4+-N and TN were 88.2%, 95.7%, and 86.4% with effluent concentrations of COD, NH4+-N and TN less than 50, 8, and 10 mg/L, respectively. Biomass and bacterial activities were also measured, with results showing more nitrobacteria in the activated sludge than in the biofilm; however, bacterial activity of the biofilm biomass and the activated sludge were similar. Nitrogen concentrations during the process were also detected, with simultaneous nitrification and denitrification found to be obvious. 相似文献
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E.D.Vicente L.A.C.Tarelho E.R.Teixeira M.Duarte T.Nunes C.Colombi V.Gianelle G.O.da Rocha A.Sanchez de la Campa C.A.Alves 《环境科学学报(英文版)》2016,28(4):246-258
Interest in renewable energy sources has increased in recent years due to environmental concerns about global warming and air pollution,reduced costs and improved efficiency of technologies.Under the European Union(EU)energy directive,biomass is a suitable renewable source.The aim of this study was to experimentally quantify and characterize the emission of particulate matter(PM_(2.5))resulting from the combustion of two biomass fuels(chipped residual biomass from pine and eucalypt),in a pilot-scale bubbling fluidized bed(BFB)combustor under distinct operating conditions.The variables evaluated were the stoichiometry and,in the case of eucalypt,the leaching of the fuel.The CO and PM_(2.5)emission factors were lower when the stoichiometry used in the experiments was higher(0.33±0.1 g CO/kg and 16.8±1.0 mg PM_(2.5)/kg,dry gases).The treatment of the fuel by leaching before its combustion has shown to promote higher PM_(2.5)emissions(55.2±2.5 mg/kg,as burned).Organic and elemental carbon represented 3.1 to 30 wt.% of the particle mass,while carbonate(CO_3~(2-))accounted for between 2.3 and 8.5 wt.%.The particulate mass was mainly composed of inorganic matter(71% to 86% of the PM_(2.5)mass).Compared to residential stoves,BFB combustion generated very high mass fractions of inorganic elements.Chloride was the water soluble ion in higher concentration in the PM_(2.5)emitted by the combustion of eucalypt,while calcium was the dominant water soluble ion in the case of pine. 相似文献
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《Journal of Cleaner Production》2008,16(2):178-191
Sewage sludge production has been increasing due to the growth of urban wastewater treatment plants. According to the enforcement of current environmental regulations, many efforts must be done to manage the large amount of generated sludge. Incineration is one potential treatment process.As far as control, design and operational guidance of processes are concerned, a successful simulation work may significantly reduce the efforts in experimental study.In this goal, a real-time simulator has been developed to describe bubbling fluidized bed incineration of sewage sludge.In the present work, details of the mathematical model are presented. The two main particularities are the buffer zone characteristics in one hand, and on the sewage sludge pyrolysis, supposed to be flash on the other one. The model results are partially validated by comparison with experimental data issued from the literature. An example of a possible scenario is given. 相似文献
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对氯酚经Fenton体系预降解后的生物流化床处理 总被引:1,自引:0,他引:1
采用Fenton-生物流化床联用工艺处理对氯酚(4-CP)模拟废水,考察了不同Fenton处理程度时4-CP的降解产物和出水的可生化性,从而确定合适的Fenton体系预处理程度.同时,采用快速排泥法进行活性炭的挂膜以实现流化床的启动,并考察了流化床连续运行阶段停留时间(RT)、pH对降解效果的影响及反应器的抗冲击能力.最后研究了4-CP在Fenton-生物流化床联用工艺中的降解过程.结果表明,当4-CP初始浓度在1~2mmol·L-1时,通过Fenton体系可使83%左右的苯环破裂,转化成小分子有机酸;利用微生物作用可使剩余的苯环类物质和大部分的有机酸被降解,出水CODCr100mg·L-1.Fenton-生物流化床工艺具有高效处理难降解废水的优点,是一项具有应用前景的废水处理技术. 相似文献
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Rice husk with high volatile content was burned in a pilot scale vortexing fluidized bed incinerator. The fluidized bed incinerator was constructed of 6 mm stainless steel with 0.45 m in diameter and 5 m in height. The emission characteristics of CO, NO, and SO2 were studied. The effects of operating parameters, such as primary air flow rate, secondary air flow rate, and excess air ratio on the pollutant emissions were also investigated. The results show that a large proportion of combustion occurs at the bed surface and the freeboard zone. The SO2 concentration in the flue gas decreases with increasing excess air ratio, while the NOx concentration shows reverse trend. The flow rate of secondary air has a significant impact on the CO emission. For a fixed primary air flowrate, CO emission decreases with the secondary air flowrate. For a fixed excess air ratio, CO emission decreases with the ratio of secondary to primary air flow. The minimum CO emission of 72 ppm is attained at the operating condition of 40% excess air ratio and 0.6 partition air ratio. The NOx and SO2 concentrations in the flue gas at this condition are 159 and 36 ppm, which conform to the EPA regulation of Taiwan. 相似文献
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针对我国城市生活垃圾热值低等特性。在流化装置上进行了城市生活垃圾与煤混燃实验,研究了在混燃过程中城市生活垃圾与煤掺烧比例及床层温度变化对NO和N2O排放浓度的影响。实验结果显示,随掺烧垃圾量逐渐增加时,NO排放浓度降低。而N2O排放浓度先降低然后增加,当城市生活垃圾与煤掺烧比例恒定时,随床温的增加NO排放浓度增加,N2O排放浓度呈下降趋势,采用前向式神经网络,以掺烧比和床温作为输入参数,对NO的排放进行预测。结果显示精度较高。 相似文献
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污泥和煤混烧特性的热重分析法研究 总被引:10,自引:2,他引:10
为了解城市污泥和煤粉混烧的燃烧规律,利用热重分析法对兰坝煤粉和某城市污泥及两试样混合物的燃烧特性进行了研究.实验结果表明,在加热速度20℃·min-1、20~1200℃的温度范围内,污泥的热重曲线存在2个明显的失重区域.在混燃过程中,煤和城市污泥基本上保持了各自的挥发分析出特性,混合试样的燃烧曲线处于污泥和煤粉燃烧曲线之间.对实验数据进行分析处理,得到了反应动力学参数活化能E和频率因子A.在掺混比例较小时(污泥质量分数为20%)对煤的活性几乎没有什么影响;而掺混比例较大时(污泥质量分数为50%、80%),存在2个反应区间,在第一温度段(大约θ<430℃)混合试样的反应特性类似于污泥,而在高温区段(θ>430℃)混合试样的燃烧特性则类似于煤. 相似文献