循环流化床锅炉掺烧高炉煤气的应用

介绍了高炉煤气的主要燃烧特性,分析了高炉煤气在循环流化床锅炉中掺烧时对炉膛换热、过热蒸汽温度、锅炉负荷、热效率、分离装置以及环境的影响,并提出了消除不良影响的相应措施。     

Have government regulations improved workplace safety? : A test of the asynchronous regulatory effects in China's coal industry, 1995-2006

Problem

Empirical studies on the effectiveness of workplace safety regulations are inconclusive. This study hypothesizes that the asynchronous effects of safety regulations occur because regulations need time to become effective. Safety regulations will work initially by reducing the most serious accidents, and later by improving overall safety performance.

Method

The hypothesis is tested by studying a provincial level aggregate panel dataset for China's coal industry using two different models with different sets of dependent variables: a fixed-effects model on mortality rate, which is defined as fatalities per 1,000 employees; and a negative binominal model on the annual number (frequency) of disastrous accidents.

Results

Safety regulations can reduce the frequency of disastrous accidents, but have not reduced mortality rate, which represents overall safety performance.

Discussion and summary

Policy recommendations are made, including shifting production from small to large mines through industrial consolidation, improving the safety performance of large mines, addressing consequences of decentralization, and facilitating the implementation of regulations through carrying on institutional actions and supporting legislation.

Impact on industry

Until recently, about 4,000 coal miners perished annually in China, demonstrating that workplace safety in China's coal industry is an urgent and important issue. This research provides evidence that safety regulations have asynchronous effects and identifies the priorities in improving safety in China's current coal mining. This may assist the Chinese government to design more effective safety improvement policies and improve the effectiveness of safety regulations and safety performance.     

基于连通法的甲烷简化机理构筑研究

采用连通法,针对甲烷复杂反应机理,成功地进行了不同水平的机理简化研究。通过建立组分依赖关系的正规化Jacobian矩阵,精确地查明了燃烧组分之间的耦合关系,分别构造出仅包含重要化学路径的两个动力学简化模型,获得的简化机理分别包含227和138个反应,分别涉及39和26种组分。通过对层流预混火焰结构的模拟,所得简化机理和原详细反应动力学机理关于火焰结构的计算吻合很好,计算结果显示,两个简化机理具有较高的模拟精度。     

Treatment of wastewater from red and tropical fruit wine production by zeolite anaerobic fluidized bed reactor

A study of the anaerobic treatment of wastewaters derived from red (RWWW) and tropical fruit wine (TFWWW) production was carried out in four laboratory-scale fluidized bed reactors with natural zeolite as bacterial support. These reactors operated at mesophilic temperature (35°C). Reactors R1 and R2 contained Chilean natural zeolite, while reactors R3 and R4 used Cuban natural zeolite as microorganism support. In addition, reactors R1 and R3 processed RWWW, while reactors R2 and R4 used TFWWW as substrate. The biomass concentration attached to zeolites in the four reactors studied was found to be in the range of 44–46 g volatile solids (VS)/L after 90 days of operation time. Both types of zeolites can be used indistinctly in the fluidized bed reactors achieving more than 80%–86% chemical oxygen demand (COD) removals for organic loading rates (OLR) of up to at least 20 g COD/L d. pH values remained within the optimal range for anaerobic microorganisms for OLR values of up to 20 and 22 g COD/L d for RWWW and TFWWW, respectively. Toxicity and inhibition levels were observed at an OLR of 20 g COD/L d in reactors R1 and R3 while processing RWWW, whereas the aforementioned inhibitory phenomena were not observed at an OLR of 24 g COD/L d in R2 and R4, treating TFWWW as a consequence of the lower phenolic compound content present in this substrate. The volatile fatty acid (VFA) levels were always lower in reactors processing TFWWW (R2 and R4) and these values (< 400 mg/L, as acetic acid) were lower than the suggested limits for digester failure. The specific methanogenic activity (SMA) was twice as high in reactors R2 and R4 than in R1 and R3 after 120 days of operation when all reactors operated at an OLR of 20 g COD/L d.     

连片生态浮床对微污染河水的净化效果

选取漕桥河的支流庙尖浜作为实验河段,以睡莲(Nymphaea alba)、菖蒲(Acorus calamus Linn)和水芹(Oenan-the javanica(Blume)DC)作为微污染水体净化的浮床植物,研究连片生态浮床的净化能力随季节的变化和浮床面积对连片生态浮床净化能力的影响。结果显示,秋-冬-春季节内植物的净化能力随季节变化呈"U"型,相应的河水水质的变化呈一个倒置的"U"型;在一定营养负荷和植物正常生长状况下,沿水流方向,氮、磷含量随浮床面积的增加而降低——春季时,随浮床面积增加,菖蒲区对TN的去除率由8.6%增加到26.7%,TP的去除率由17.1%增加到58.2%,水芹区对TN和TP的去除率最高可达22.0%和28.0%。研究表明连片生态浮床是河道水质改善的有效可行的方法之一,可为太湖入湖河流的营养物质控制提供科学依据。     

不同粒径零价铁（ZVI）对污水污泥H_2S和CH_4释放速率的影响

考察了不同粒径零价铁（ZVI）,包括200目普通铁粉（200m-ZVI）、800目超细铁粉（800m-ZVI）和纳米铁粉（nZVI,粒径=20 nm）,对污水污泥的硫化氢和甲烷释放速率的影响。研究发现：（1）在22 d内,添加0.1%的200m-ZVI使污泥的硫化氢释放速率提高48.0%,而添加0.1%的800-ZVI和nZVI,则使污泥的硫化氢释放速率分别降低33.1%和77.1%;（2）不同粒径ZVI均可以提高污泥沼气中的甲烷浓度,且依次为nZVI〉800m-ZVI〉200m-ZVI;（3）在23 d内,添加0.1%的200m-ZVI和nZVI使污泥的甲烷累计产生量分别提高了15.5%和40.6%,而添加0.1%800m-ZVI则使甲烷产生量降低了12.5%。nZVI可以有效控制污泥的硫化氢释放,并显著提升污泥在厌氧发酵过程的产甲烷速率。     

垃圾填埋场甲烷氧化菌及甲烷通量的研究

采用静态箱法、滚管计数法和气相色谱法,对6个不同封场时间填埋区的甲烷通量、覆土层甲烷氧化菌数量和甲烷氧化速率的变化趋势进行了测定,并分析了它们与封场时间、植被覆盖率等因素之间的相关性。结果发现6个填埋区甲烷通量的变化范围在-0.34～5.31 mg/(m2.h)之间;覆土层甲烷氧化菌的数量范围为3.10×107～20.77×107 cfu/g干土,甲烷氧化速率在1.65×10-8～4.34×10-8mol/(h.g)之间。覆土层甲烷氧化菌的数量与甲烷氧化速率呈正相关,但前者并不是后者的决定性因素;甲烷通量高时可刺激甲烷氧化菌数量及氧化速率的提高,且三者均与封场时间呈显著负相关,与植被覆盖率呈负相关;当含水率大于15%时,随着覆土层含水率的增加,甲烷氧化速率呈下降趋势;覆土pH、有机质和铵态氮与甲烷氧化速率等无明显相关性。提高覆土层的甲烷氧化速率可有效减少垃圾填埋场的甲烷排放。     

阴极液及底物浓度对AFB-MFC同步废水处理及产电性能影响

为了提高厌氧流化床微生物燃料电池（AFB-MFC）的性能,并为双室MFC寻找价廉、易得、无污染的阴极液,在曝气量16～24 L/h、温度（35±2）℃、回流量10.2 L/h、阴极底边距阴极室内底部17.3 cm、外电阻250 Ω、水力停留时间（HRT）14.0～14.9 h以及进水pH 7.81～8.37下,研究了阴极液及底物浓度对系统产电及废水处理性能的影响。结果表明,使用缓冲溶液、阳极室出水和自来水作阴极液时,自来水的产电性能最佳,阴极液种类不影响系统有机基质的去除。以自来水为阴极液时,阴极液pH及电导率随运行时间增加而增加,COD去除率为80.11%～89.29%,输出电压及功率密度开始随运行时间增加而增加,之后稳定在440～452 mV和48.40～51.08 mW/m²之间。增加底物浓度对COD去除率影响不大,而输出电压及功率密度随底物浓度增加而下降;底物COD浓度由3 307.09 mg/L增至9 520 mg/L时,COD去除率在85.77%～94.44%之间,输出电压及功率密度则分别由449 mV和50.40 mW/m²下降至406 mV和41.21 mW/m²。自来水作阴极液可避免二次污染及阴极液对阳极室微生物的影响,并得到高的产电能力。     

曝气生物流化床处理高氨氮粪便污水

应用好氧曝气生物流化床反应器处理动车集便器粪便污水,研究反应器同步硝化反硝化脱氮及去除COD效能,以及DO对处理效能的影响,通过镜检观察反应器内微生物特性,探究反应器同步硝化反硝化脱氮机理。结果表明,反应器维持DO在2.5 mg/L左右时,对粪便污水中氨氮、TN和COD的去除率分别达99.8%、84.1%和95.5%,在好氧曝气生物流化床反应器中,实现同步硝化反硝化脱氮并去除有机物。分析认为,反硝化脱氮主要发生在生物膜内的厌氧微环境,反硝化反应主要由厌氧反硝化菌完成,曝气生物流化床反应器同步硝化反硝化脱氮机理主要从微环境理论解释。     

人工浮床对汾江河水质净化的研究

对佛山市汾江河内布置浮床的水域的7个断面进行采样监测,分析了布置浮床侧与未布置浮床侧各水质指标的差异,以考察人工浮床对汾江河水质的净化效果。同时比较了圆币草、水罂粟、梭鱼草、狐尾草、美人蕉和鸢尾6种浮床植物的生物量和氮磷吸收量。结果表明,布置人工浮床一侧的水质TN、TP、COD和NH4＋-N含量均显著低于未布置浮床一侧的水质,表明人工浮床对水体水质的有净化效果。总面积约4 900 m2的浮床植物经过3个月的生长,从水体中共吸收了192.5 kg的氮和76.1 kg的磷。6种浮床植物中,狐尾草的净增生物量最高,达到64.2 kg/m2;圆币草次之,为62.2 kg/m2。狐尾草和圆币草对氮磷的吸收能力在6种植物中处于较高水平,每平方米狐尾草和圆币草从水体中分别吸收了51.61g氮、19.79 g磷和46.90 g氮、22.93 g磷。综合比较得出,狐尾草和圆币草在生物量和氮磷吸收量上均保持在较高水平,是较好的浮床植物。本研究为人工浮床在南方类似河流中的应用及植物选择提供了参考依据。