错流内滤式滤芯脉喷清灰的数值模拟

错流式过滤除尘技术利用切向风流抑制尘饼生长变厚,具有过滤阻力上升缓慢的优点,采用脉喷气流撞击设置在滤芯外的横向挡板并产生局部静压可实现内滤式滤芯的清灰。构建CFD数值模拟考察了喷吹气流的分布,分析了喷嘴入口处的喷吹压力和挡板位置对脉冲喷吹性能的影响,设计并考察了挡板往复式喷吹策略。结果表明：滤芯压力随喷嘴入口压力升高而增加,确定了最佳喷嘴入口压力为5 000 Pa;挡板位置的变化显著影响清灰的有效区,对于1 000 mm长的滤芯,挡板位置为500 mm和350 mm分别实现350~500 mm和0~350 mm区域的有效清灰;相比普通喷吹,设计的挡板往复式喷吹 (挡板位置依次为350、500、650、500 mm) 可实现滤芯喷吹压力增大1.57倍、均匀性提升7.17倍。该研究结果可为内滤式滤芯脉喷清灰提供参考。     

内循环流化床烟气脱硫技术的实验研究

通过对流化床烟气脱硫吸收塔塔顶和塔底结构的改进,开发出一种新的内循环流化床烟气脱硫工艺。该工艺以60～80目细砂作为主要床料,在流化气速为2～5m/s情况下,实现了绝大部分固体颗粒在脱硫塔内的内循环,从而强化了热质传递,避免了粘壁现象。考察了各种因素对脱硫效率的影响,结果表明,绝热饱和温度差是影响脱硫效率的显著因素,颗粒浓度是保证系统稳定运行的关键因素。在Ca/S为12和颗粒浓度为10kg/m3条件下,系统能连续稳定运行,脱硫效率达90%以上。     

IC+A/O工艺在制药废水处理中的应用

针对某制药公司生产废水的特点,采用高效厌氧反应器——内循环厌氧反应器(简称IC工艺)+A/O工艺进行处理。系统稳定运行后,在进水ρ(COD)为3 500 mg/L、ρ(SS)为300 mg/L时,去除率分别达到97.9%、92.5%。处理后出水水质稳定,达到GB 8978—1996《污水综合排放标准》一级标准。     

电厂内冷水超净化处理出现的问题及处理方法

简要介绍了河北某电厂内冷水超净化处理工艺,并对运行中出现的问题及处理进行了详细讨论,实践证明,采用超净化处理技术能够保证该电厂内冷水水质符合标准要求。     

EFFECTIVENESS OF ALUM IN A WEEDY,SHALLOW LAKE1

ABSTRACT: An alum treatment in Long Lake (mean depth, 2 m) in 1980 has been effective at controlling internal loading of phosphorus for four years. The fifth summer after treatment, the lake returned to its pro-treatment state. Lake P content decreased from a summer average of 65 μg/L during 1976–1978 to about 30 μg/L during four years following treatment. In 1985, summer P content was 61 μg/L. Algal abundance, species composition, and transparency have responded proportionately with P. Alum effectiveness apparently declined because the floe layer tended to sink and become dispersed at a deeper level in the sediment, as well as become covered with new, P-rich sediment. Iron-reduction may be the principal mechanism for internal P loading, although the lake is unstratified and anoxia is usually not pronounced.     

Upstream Turbulence Effect on Pollution Dispersion

Experiments have been carried out to investigate turbulence at and above roof-level in an urban environment, and to predict the behaviour of street pollution from experiments using dye dispersion, for different roughness conditions and bed geometries. The flow in the boundary layer above an idealised urban environment has been simulated in a laboratory water flume. Comparisons have been made for the same model street canyon with and without the presence of upstream roughness. In the tests reported here, model street canyons were aligned perpendicular to the flow direction, and velocity measurements made within and above the model street canyons using a laser Doppler velocimeter (LDV). Flow visualisation techniques have also been used to confirm the gross flow features from streak images. Turbulence generated from the upstream roughness has a significant effect on the turbulence production and dispersion behaviour of the dye simulating pollution in street canyons.     

内压作用下含体积型缺陷弯管极限载荷研究

油气管道一旦发生泄漏失效容易引发爆炸等灾难性事故,而管路中的弯管段是容易发生失效的部分,弯管段承载能力的高低将影响整个管道系统的安全性。为了解决油气管线中弯管的失效问题,考虑几何和材料非线性,建立内压作用下含体积型缺陷弯管的有限元模型,并与爆破试验结果对比验证模型的有效性,确定管道的失效判定准则。研究表明影响弯管极限载荷的主要因素有缺陷的几何尺寸、相对位置以及弯曲半径。基于模拟计算,讨论各因素对含缺陷弯管极限载荷的影响规律,通过对计算结果进行非线性拟合,提出内压作用下含体积型缺陷弯管的极限内压预测公式。该公式将为含缺陷弯管的剩余强度评价和完整性评价提供一定依据。     

湖泊疏浚方式对内源释放影响的模拟研究

通过室内模拟试验,探讨不同疏浚方式对内源氮磷释放的影响以及不同湖区疏浚后氮磷释放的差异性.理想式疏浚和绞吸式疏浚沉积物磷的释放速率分别为未疏浚的20%和72%,并且A(内湾)湖区沉积物磷的释放速率是B(外湾)湖区的80%左右.理想式疏浚和绞吸式疏浚后沉积物氨氮的释放速率分别是抓斗式疏浚的40%和83%,但是这几种疏浚方式对氨氮的释放并没有达到理想的效果,在短期内对氨氮的释放甚至是起促进作用的,并且A湖区(内湾)氮的释放速率约是B湖区(外湾)的1.5倍,这应该看作是湖泊疏浚工程一个潜在的负作用.研究结果表明,理想式和绞吸式疏浚方式对内源释放有较好的控制作用,在外源输入得到有效控制的前提下,底泥疏浚可以作为湖泊沉积物污染修复的手段,并且结合目前的技术手段,在太湖的疏浚工程中应尽量选择绞吸式疏浚.     

城市污水深度处理及中水回用

介绍了一套日处理量9 600 t的中水回用工程,该工程应用生化+两级过滤+反渗透工艺深度处理二级城市污水并将产水回用于热电厂的循环冷却水及锅炉补给水的源水。探讨了该工艺关键单元的作用及特点并考察了其运行效果。结果表明:该工艺运行稳定,产水各项指标满足该热电厂对回用水的要求。