Prediction of Particulate Loading in Exhaust from Fabric Filter Baghouses with One or More Failed Bags

Abstract

Loss of filtration efficiency in a fabric filter baghouse is typically caused by bag failure, in one form or another. The degree of such failure can be as minor as a pinhole leak or as major as a fully involved baghouse fire. In some cases, local air pollution regulations or federal hazardous waste laws may require estimation of the total quantity of particulate matter released to the environment as a result of such failures. In this paper, a technique is presented for computing the dust loading in the baghouse exhaust when one or more bags have failed. The algorithm developed is shown to be an improvement over a previously published result, which requires empirical knowledge of the variation in baghouse pressure differential with bag failures. An example calculation is presented for a bag-house equipped with 200 bags. The prediction shows that a small percentage of failed bags can cause a relatively large proportion of the gas flow to bypass the active bags, which, in turn, leads to high outlet dust loading and low overall collection efficiency from the baghouse.     

Effectiveness and mechanisms of hydrogen sulfide adsorption by camphor-derived biochar

The characteristics and mechanisms of hydrogen sulfide (H₂S) adsorption on a biochar through pyrolysis at various temperatures (100 to 500°C) were investigated. The biochar used in the current study was derived from the camphor tree (Cinnamomum camphora). The samples were ground and sieved to produce particle sizes of 0.4 mm to 1.25 mm, 0.3 mm to 0.4 mm, and <0.3 mm. The H₂S breakthrough capacity was measured using a laboratory-designed test. The surface properties of the biochar were characterized using pH and Fourier-transform infrared spectroscopy (FTIR) analysis. The results obtained demonstrate that all camphor-derived biochars were effective in H₂S sorption. Certain threshold ranges of the pyrolysis temperature and surface pH were observed, which, when exceeded, have dramatic effects on the H₂S adsorption capacity. The sorption capacity ranged from 1.2 mg/g to 121.4 mg/g. The biochar with 0.3 mm to 0.4 mm particle size possesses a maximum sorption capacity at 400°C. The pH and FTIR analysis results showed that carboxylic and hydroxide radical groups were responsible for H₂S sorption. These observations will be helpful in designing biochar as engineered sorbents for the removal of H₂S.

Implications: This paper studies the potential of biochar derived by camphor to adsorb hydrogen sulfide at environmentally sustainable temperatures. The different sizes of the biochars and the different temperatures of pyrolysis for the camphor particle have a great impact on adsorption of hydrogen sulfide.     

2株油烟降解优势菌株的筛选及性能研究

通过以油烟冷凝液为惟一碳源的选择培养基初筛,从长期受到油烟严重污染的土壤中筛选出具有降解油烟污染物能力的优势菌株XJ01、XJ03。研究了其最佳生长条件及降解性能,并对其进行了生理生化特征及分子生物学鉴定。研究表明,XJ01、XJ03最佳生长温度分别为35℃、30℃,最佳生长pH均为7,摇床转速均为120r／min,最佳降解时间分别为48h和36h;在最佳降解条件下,xJ01、XJ03总降解量分别达4．47113g／L和4．18ing／L,降解过程中,降解液pH值持续下降,生物量先增加后下降。经分子生物学鉴定,菌株XJ01、XJ03分别与铜绿假单胞菌群（Pseudomonasaeruginosagroup）和克雷伯氏菌属（Klebsiellasp．）同源性最高均达到100％。     

嗅觉实验配气方法的改进及影响因素研究

配制气体样品是异味测试及相关研究的基础工作,配气稳定性直接影响测试结果准确度。三点比较式臭袋法使用微量进样针量取并转移液体标准物质到3L无臭气袋的传统配气方法。对于异味阈值较小物质或样品浓度处于较低范围时,为了降低取样体积波动对配气精度和稳定性的影响。提出先将标准注入100mL玻璃注射器,充分挥发混匀后再转移部分气体到无臭气袋的两步式配气方法。结果表明,2种配气方法的准确度不存在显著差异,但两步式配气法的配气稳定性明显优于传统方法。此外,研究还发现,常见异味物质在被注人气袋后3min内便能完全挥发并混合均匀。除一些挥发性和吸附性极强的物质外,气袋内的异味物质气体浓度能在配好后20min内基本保持不变。     

亚铁离子生物氧化-还原法连续脱除硫化氢

为了降低工业废气中的硫化氢去除工艺成本和运行费用,对三价铁盐吸收与氧化亚铁硫杆菌对Fe²⁺的生物氧化联合作用脱除H₂S进行了研究。通过生物氧化塔中的固定化氧化亚铁硫杆菌细胞再生的Fe³⁺溶液,在H₂S还原吸收塔中脱除H₂S。通过单因素实验分别优化了生物氧化塔和H₂S吸收塔的运行参数,在生物氧化塔曝气量为150 L/h,停留时间为11 h,吸收液中Fe³⁺浓度为0.121~0.143 mol/L,吸收液流量为0.3 L/h,进气量为100 L/h条件下,进气中H₂S浓度分别为2.28和9.11 mg/L,系统连续运行至200 min时趋于相对稳定,当系统连续运行稳定时,H₂S的脱除率可分别达到95%和91%,脱除效果显著。     

高比表面CuO/SiO2杂化材料的制备及其催化苯酚降解性能

研究了以聚乙二醇为模板剂、采用正硅酸乙酯(TEOS)为硅源制备掺杂铜的多孔SiO2的方法。开发了一步完成多孔材料制备和掺杂的新工艺。研究了不同的铜元素掺杂量对样品性能的影响。采用低温氮吸附、扫描电镜(SEM)和傅里叶变换红外光谱(FTIR)等方法表征了样品的比表面、孔结构和表面基团等信息。研究了所制备的多孔材料和H2O2共同降解水中苯酚的能力,探索了H2O2用量、初始pH等条件对降解效果的影响,研究发现负载铜的催化剂可以在很宽的pH范围内和H2O2协同使用,这可能是因为铜元素被牢固负载于多孔SiO2上,避免了金属离子在高pH下的沉淀反应。     

广东省“十三五”期间生态环境质量状况及变化特征

分析了"十三五"期间广东省生态环境质量状况及变化特征,结果表明:"十三五"期间,广东省生态环境质量明显改善,2020年全省城市环境空气优良天数比例为95.5%,PM_2.5年均质量浓度为22 μg/m³,重度酸雨污染城市清零,地表水水质优良比例为86.3%,近岸海域海水水质优良面积比例为89.5%,自然生态质量总体为优。与2015年相比,2020年全省城市环境空气优良天数比例上升1.0百分点,PM_2.5年均质量浓度下降29.0%,降水pH均值上升0.36个pH单位,酸雨频率下降12.9百分点。与2016年相比,地表水水质优良比例上升6.9百分点,重度污染比例下降8.5百分点,近岸海域海水水质优良面积比例上升9.1百分点,城市声环境总体稳定,自然生态质量稳中向好。但大气O₃尚未进入下降通道,个别河段仍存在重度污染,海洋生态环境管理基础较薄弱。在协同减污降碳新形势下,推动生态环境质量持续改善仍面临较大挑战。     

“十三五”期间洪泽湖底栖动物多样性调查及趋势分析

基于2015—2020年洪泽湖底栖动物监测数据,利用生物多样性指数模型方法对洪泽湖底栖动物的种类组成及多样性进行分析,并对水质污染状况进行评价,结合广义线性模型方法对洪泽湖生态变化趋势进行预测。结果表明,“十三五”期间洪泽湖底栖动物种类数总体呈上升趋势,生物多样性有所改善,底栖动物优势种均为河蚬。Goodnight-whitely修正指数(GBI)、生物学污染指数(BPI)、生物指数(BI)以及生物耐污敏感性指标指数(BMWP)4种污染状况评价指数对洪泽湖水质评价结果表明,“十三五”期间洪泽湖生态系统状况基本平稳,水质污染状况介于清洁至轻污染之间,龙集镇北的水质状况应引起重视。模型预测结果显示,“十四五”末洪泽湖生物多样性无明显变化,水质持续保持稳定。研究结论可为水生生物多样性保护提供科学依据。     

Organochlorine pesticides in the dust fall around Lake Chaohu, the fifth largest lake in China

The residual levels of organochlorine pesticides (OCPs) in the dust fall around Lake Chaohu were measured using gas chromatography mass spectrometry from April 2010 to March 2011. The fluxes, components, temporal–spatial variations, and sources of OCPs were also analyzed. Twenty-one types of OCPs were detected in the dust fall samples around Lake Chaohu, with a total concentration of 51.54?±?36.31 ng/g and a total flux of 10.01?±?13.69 ng/(m² day). Aldrin (35.3 %), endosulfan (39.1 %), dichlorodiphenyltrichloroethanes (DDTs) (49.8 %), and isodrin (37.1 %) were the major OCPs in the spring, summer, autumn, and winter, respectively. Both the residual level and the flux were higher in the spring than in other seasons and higher at the outer lake sampling sites than inner lake sampling site. The potential source of the hexachlorcyclohexanes in the dust fall may be recent lindane usage. The DDTs mainly came from historical dicofol usage, and a significant input of DDT was found during April and June. The presence of endosulfan may be due to the present use of technical endosulfan. The aldrin in the dust might be due to its occasional usage, and isodrin may be a result of long-distance transport from other countries.     

供气条件对小球藻固定二氧化碳的影响

对三种不同的供气条件下,小球藻对CO2的固定速率进行了研究,结果表明,用鼓泡系统供气时,在CO2浓度渐增的条件下比固定CO2浓度条件下小球藻对CO2固定速率高,用旁路中空纤维组件吸收供气系统供气时,CO2的传递率高于鼓泡供气系统;这两种供气系统中小球藻的生长模式和CO2的固定率相似。