同步进出水SBR设备最佳进水方式流态模拟

借助流体计算软件Fluent对某同步进出水SBR设备4种不同进水位置以及3种进水孔排布分别进行流态模拟,根据模拟结果得到最佳的进水方式;同时在该进水方式下对进水流量为0.5、0.7、1.0、1.3和1.5 m3/h时反应器内的流态分布情况进行了数值模拟,最后通过示踪剂实验与模拟结果对比验证。对于实验用SBR(长×宽×高为2 m×2 m×1.2 m),进水流量1.0 m3/h是最佳进水流量,此时反应器内流态稳定,进水区域主要分布于反应器中下部以及远离堰口的池壁附近,死水区面积较小,冲击负荷适中,进水对出水水质影响较小;当进水流量小于1.0 m3/h时,进水主要分布于反应器池底,对角线方向以及远离进水端池壁附近3个区域且彼此相对独立,池内死水区面积较大;当进水流量大于1.0 m3/h时,进水冲击负荷过大,迅速形成短流,影响出水水质。     

曝气条件对浸没式膜生物反应器内流场的影响

为深入研究流场动力学特性对浸没式膜生物反应器系统内膜面污染的控制,应用fluent软件对浸没式膜生物反应器内气液两相流动进行了三维数值模拟研究。采用标准k-ε湍流模型和欧拉多相流模型,考察了改变曝气条件对膜面气液速度场及气含率分布的影响。模拟结果表明,在相同曝气强度下,1 mm曝气孔径下膜面气液两相的速度增加较孔径2 mm、3 mm的快;曝气孔径为1 mm时,膜面的液相速度随着曝气强度的增加逐渐增大;曝气孔径为1 mm时,曝气量为5.5 m3/h所形成的漩涡区较大,膜面气含率值较高且分布较均匀,气液两相接触面积较大,膜面冲刷效果较好;模拟观察到反应器底部靠近壁面局部气含率较低,不利于活性污泥中微生物的生长,需要进一步优化曝气和反应器结构。     

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。     

电弧流溶胞技术促进污泥厌氧消化

为提高污水厂处理污泥时的厌氧消化速率,利用电弧流溶胞技术处理剩余污泥,研究电弧流溶胞技术对污泥破解预处理效果的影响.实验结果表明,与未经预处理的污泥相比,电弧流溶胞处理能够明显提高污泥厌氧消化效率,增加有机物含量和沼气产量.其中,经处理后的污泥TS、VS剩余量分别降低了8.3%和6.3%,COD增加了11.9%.厌氧系统平均产气量平均增加79.76 L/d,增加率45.82%,甲烷含量增加1.03 L/d,增加率102%.由此说明,电弧流溶胞技术可以提高厌氧消化反应中有机物的去除率,有效促进厌氧消化中污泥的水解过程,显著增加甲烷气体的产生量.在综合考虑运行费用和污泥消化效果的前提下,采取适宜的电弧流强化处理措施有一定的积极意义.     

密相塔半干法烟气脱硫塔内加湿降温及其对脱硫效率的影响

为了实现密相塔半干法脱硫工艺的精确加湿进一步提高系统脱硫效率,利用推导出的传热传质计算方法,得到烟气温度降低和加水量的关系.结合3组密相塔半干法工程实际数据,发现理论计算值和实测值误差区间仅为2.9%~5.4%.通过选取河北某钢厂210 m2烧结烟气密相塔半干法脱硫项目实际在线检测数据,发现循环脱硫灰含湿量为3%的系统脱硫效率整体高于含湿量为5%和4%的样品,最大值达93.56%.通过粒度分析、扫描电镜、X射线衍射及差热-热重对2种不同含湿量的循环脱硫灰进行表征,结果表明,含湿量为3%的循环脱硫灰较含湿量为5%的样品粒径小、比表面积大,无团聚现象,物相分析还证实相对于含湿量为5%样品,其Ca(OH)2和结晶水含量少,几乎都是CaSO4和CaSO3干态物质,因此脱硫反应进行彻底,脱硫效率较高.     

Thermodynamic investigation and hydrate inhibition of real gas flow through orifice during depressurization

A thermodynamic procedure has been proposed which can be used to predict the gas pressure, temperature and flow rate through orifice upon chock flow condition, using equation of state (EOS). The procedure applied for emergency depressurization operation incorporating the Peng-Robinson EOS and validated by comparing flow rates of a multi-component hydrocarbon gas mixture for thirteen experimental cases. The average absolute deviations of the predicted flow rates for orifice discharge coefficients of 0.85 and 0.9, are 7.36% and 2.03%, respectively. The corresponding error for API 520 (American Petroleum Institute Recommendation Practice 520) method is 6.91%. In this work, the hydrate formation temperature and hydrate inhibitor type and its required weight fraction for preventing the hydrate formation upon orifice and its upstream conditions are evaluated by the EZ-Thermo software using the Moshfeghian–Maddox method. The results qualitatively show that the hydrate prevention is essential for the safety of the operation due to low temperature condition.     

芦苇碳源-表面流人工湿地对农田退水脱氮的长期效能研究

针对农田退水NO₃^--N占比高、C/N低,氮污染难以去除的问题,将经济易得的芦苇(Phragmites australis)茎叶碎段装填在表面流人工湿地(packed surface flow construct wetland,PSFW)的表层作为外加碳源,以研究其长期运行情况下的脱氮效能。结果表明：第29~149天,外加芦苇茎叶碎段的PSFW的脱氮效能明显高于无芦苇茎叶碎段的空白PSFW₀;进水NO₃^--N和TN浓度分别为(16.4±1.0)和(17.7±2.0)mg/L,HRT按3、4和2 d运行时,HRT为4 d时脱氮效能最优,PSFW对NO₃^--N和TN去除率分别为(87.4±6.0)%和(74.1±6.0)%,PSFW₀去除率仅为(14.4±4.0)%和(14.4±3.0)%;第150~269天,PSFW的脱氮效能稍高于PSFW₀,在进水NO₃^--N和TN浓度分别为(10.4±1.0)和(10.8±1.0)mg/L,HRT按3、2和1 d运行时,HRT为3 d时脱氮效能最优,PSFW对NO₃^--N和TN的去除率分别为(91.9±7.0)%和(90.2±7.0)%,PSFW₀去除率分别为(91.3±5.0)%和(86.4±6.0)%。第270~334天,PSFW的脱氮效能稍低于PSFW₀;进水NO₃^--N和TN浓度分别为(5.7±0.4)和(7.2±0.8)mg/L,HRT为3 d时,PSFW对NO₃^--N和TN的去除率分别为(88.6±10.0)%和(82.5±7.0)%,PSFW₀去除率分别为(94.0±6.0)%和(87.8±3.0)%。     

采场通风方式与瓦斯运移规律研究

采场是煤矿生产的核心地带,而采场通风系统是确保采场作业安全,创造良好生产环境的重要环节。本文以采场风流流动及瓦斯运移理论为基础,通过现场试验、模型模拟试验及计算机模拟研究等方法,着重研究了中国常用的和有发展前途的走向长壁后退式U型通风方式、U+L型通曲方式、后退式Y型通风方式条件下采场风流流动及瓦斯运移规律。     

Modeling Parent and Metabolite Fate and Transport in Subsurface Drained Fields With Directly Connected Macropores1

Abstract: Few studies exist that evaluate or apply pesticide transport models based on measured parent and metabolite concentrations in fields with subsurface drainage. Furthermore, recent research suggests pesticide transport through exceedingly efficient direct connections, which occur when macropores are hydrologically connected to subsurface drains, but this connectivity has been simulated at only one field site in Allen County, Indiana. This research evaluates the Root Zone Water Quality Model (RZWQM) in simulating the transport of a parent compound and its metabolite at two subsurface drained field sites. Previous research used one of the field sites to test the original modification of the RZWQM to simulate directly connected macropores for bromide and the parent compound, but not for the metabolite. This research will evaluate RZWQM for parent/metabolite transformation and transport at this first field site, along with evaluating the model at an additional field site to evaluate whether the parameters for direct connectivity are transferable and whether model performance is consistent for the two field sites with unique soil, hydrologic, and environmental conditions. Isoxaflutole, the active ingredient in BALANCE^® herbicide, was applied to both fields. Isoxaflutole rapidly degrades into a metabolite (RPA 202248). This research used calibrated RZWQM models for each field based on observed subsurface drain flow and/or edge of field conservative tracer concentrations in subsurface flow. The calibrated models for both field sites required a portion (approximately 2% but this fraction may require calibration) of the available water and chemical in macropore flow to be routed directly into the subsurface drains to simulate peak concentrations in edge of field subsurface drain flow shortly after chemical applications. Confirming the results from the first field site, the existing modification for directly connected macropores continually failed to predict pesticide concentrations on the recession limbs of drainage hydrographs, suggesting that the current strategy only partially accounts for direct connectivity. Thirty‐year distributions of annual mass (drainage) loss of parent and metabolite in terms of percent of isoxaflutole applied suggested annual simulated percent losses of parent and metabolite (3.04 and 1.31%) no greater in drainage than losses in runoff on nondrained fields as reported in the literature.     

云南近百年来温度雨量的变化特征分析

用气候倾向率、Morlet小波方法,对云南10个站1901-2007年的年降水和平均温度资料分析表明:100年来云南平均增温速率为0.031℃/10a。近50年来全省平均增温速率为0.242℃/10a,略高于全国的增温,增温最大的是滇中的昆明、滇南的普洱,分别为0.442℃/10a和0.409℃/10a,并且西部明显高于东部。100年来云南年降水呈减少趋势,平均速率为7.288mm/10a,近50年来,年降水量减少平均速率为6.66mm/10a。但云南降水的区域分异非常明显,云南的东部、中部降水减少;而滇西北和滇东南地区降水增加。云南气温明显的年代际变化是32年,发生了3次突变。年降水呈明显的年代际及年际振荡,具有16～32年、4～8年周期。