SCR脱硝系统烟道内流场优化

为了改善选择性催化还原法(SCR)催化剂上游烟气的流场、温度场和浓度场分布,基于CFD仿真分析技术,建立了整个脱硝系统三维模型,并通过优化导流板及整流格栅,使得速度标准偏差、浓度标准偏差、温度偏差、速度偏转角以及压降等性能指标都满足设计要求,在满足脱硝效率和氨逃逸率前提下,大大降低了烟气对催化剂层的冲刷,保证催化剂的使用寿命。最后,为了合理布置吹灰器,对优化结构下粉尘颗粒在烟道内的运动情况进行了仿真分析研究,为设计提供了依据。     

A full-scale sequencing batch reactor system for swine wastewater treatment

A full-scale sequencing batch reactor (SBR) system was evaluated for its ability to remove carbon and nitrogen from swine wastewater. The SBR was operated on four, six-hour cycles each day, with each cycle consisting of 4.5 hours of “React,” 0.75 hours of “Settling”, 0.75 hours for “Draw” and “Fill.” Within each cycle, an amount of wastewater equivalent to about 5% of the reactor volume (5,500 litres) was removed and added. The SBR system was able to remove 82% of biochemical oxygen demand (BOD) and more than 75% of nitrogen. Even though the SBR effluent, with an average effluent BOD₅ of about 588 mg L^{? 1}, did not meet the discharge criteria, it enabled a reduction of the land base required for land application of swine wastewater by about 75%. Results indicated that the SBR system was a viable method for the treatment of swine wastewater.     

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.     

烟气脱硝技术应用现状与研究进展

氮氧化物的污染危害是一个不容忽视的问题,有效控制氮氧化物污染已经刻不容缓。针对目前氮氧化物污染状况,分析了烟气脱硝的重要性与紧迫性。介绍了国内外烟气脱硝技术应用现状和研究进展,对各类烟气脱硝技术进行了分析和对比。针对目前烟气脱硝技术以干法为主的现象,着重介绍了SCR和SNCR两种脱硝技术。     

外循环式UASB反应器处理高浓度酒精废水

利用改进型上流式厌氧污泥床反应器在中温条件下处理高浓度酒精废水,研究反应器的启动影响因素及颗粒污泥形成过程,分析反应器运行特性。在容积负荷为10.39 kg COD/(m3.d),COD去除率达90.2%,VFA在300 mg/L以下,平均产气率为0.328 m3/kg COD,取得最佳的运行效果,为高浓度酒精废水的处理应用提供科学依据。     

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。     

氮掺杂TiO2可见光光催化剂的制备及性能

以尿素和钛酸丁酯为原料,通过溶胶-凝胶法低温下制备了高可见光催化活性的氮掺杂TiO2(NDT)光催化剂,采用XRD、TEM、BET和UV-Vis DRS等测试手段对其进行了表征,并在自制光催化反应器中降解甲基橙评价了样品的光催化活性。结果表明,当氮与钛的摩尔比为0.5∶1时,350℃焙烧的样品(NDT350)具有最佳的可见光光谱吸收和光催化活性,该催化剂为锐钛矿晶相,平均粒径为21 nm,比表面积为89.13 m2/g。可见光辐照下,NDT350降解甲基橙的表观反应速率常数为1.381×10-2min-1,是商业P25催化剂的16.85倍。NDT350优良的可见光催化活性与其大的比表面积和强烈的可见光光谱吸收有关。     

复合生物膜-活性污泥反应器同步脱氮除磷

通过实验研究比较了复合生物膜-活性污泥反应器(HY)和传统活性污泥反应器(AS)的脱氮除磷效果。结果表明,在水力停留时间(HRT)16 h、污泥龄12～15 d、水温19～21℃、pH 6.3～7.8的条件下,复合生物反应器比活性污泥反应器运行更稳定,未发生污泥膨胀。在相同运行条件下,复合生物反应器对COD、TN和TP的去除率分别为95%、91%和98%,而活性污泥反应器对COD、TN和TP的去除率分别为85%、84%和90%。稳定工况下复合生物反应器的比硝化、比反硝化速率,比吸磷、比释磷速率均高于活性污泥反应器,且微生物相更加丰富。通过建立16S rDNA克隆文库发现生物膜和活性污泥的微生物群落结构均具有高度多样性,但生物膜微生物的微生物相比活性污泥更复杂。     

烟气同时脱硫脱硝化学反应的可能性分析

根据烟气气体组分情况,将可能发生的化学反应方程式进行筛选,确定独立反应个数。通过热力学计算得到了标准状态下热力学函数值,进而求得了不同温度下的热力学性质。通过标准生成自由焓、标准吉布斯自由能变、标准熵变的计算,分析了烟气同时脱硫、脱硝中发生化学反应的可能性,为烟气同时脱硫、脱硝动力学理论的研究打下了基础。     

600MW燃煤机组SCR脱硝工程设计特点

介绍了我国第一批烟气脱硝工程之一——山西阳城电厂600MW燃煤机组SCR工程的设计特点,包括反应器本体设计、催化剂选型设计和氨区设计等。结合实践经验,对脱硝系统设计提出了一些优化建议。