共查询到16条相似文献,搜索用时 500 毫秒
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理论和实践经验均表明,内陆核电厂采用多孔扩散器有利于加快近排放口区域液态流出物的掺混稀释。基于美国环保署推荐的近区模拟工具——CORMIX专家系统,对低环境流速水文条件下的内陆核电厂的多孔扩散器开展了研究。分析表明:对于近岸布置的多孔扩散器,在低环境流速、相对较强射流以及水深较深条件下,(1)扩散器主管长度Ln与排放口下游断面的最小相对稀释比例H呈正相关,喷口直径D与H呈负相关,喷口水深HD与H呈正相关;在排热量相同的情况下,流量Q与H呈正相关。(2)对于排放口下游1 000 m断面处的最小相对稀释比例H1 000 m,各几何参数灵敏度由高到低排序为,喷口直径D、喷口数量n、主管长度Ln。研究结论可供内陆核电厂液态流出物排放工程的设计及优化参考。 相似文献
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为提高温排放的初始稀释度、减小排口近区超标区域,扩散器常被用于电厂排海工程。本文采用CORMIX经验模型与Realizable k-ε紊流模型相结合的方法,开展了孟加拉湾河口水域燃煤电厂排水扩散器的参数优化及温排水稀释特性研究。首先分析了扩散器长度、出流角度、出流流速等参数对初始稀释的影响,并对扩散器型式进行了比选,提出潮汐水域采用交错型扩散器有利于增大近区稀释度。针对推荐扩散器,研究依据准恒定假设,模拟了涨潮、高平、落潮、低平四个特征潮态的温排水稀释扩散过程。结果表明:不同潮态的温度场空间结构、温升分布及稀释效果具有显著差异,低平潮对温排水掺混稀释最为不利;涨潮与落潮时顺流向与逆流向的喷口射流结构也不尽相同,顺流向射流更加细长。研究成果可为电厂排放口工程设计与环境影响评价提供技术支撑,也可为浅水型海域扩散器选型提供参考。 相似文献
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由于内陆厂址较沿海厂址受纳水体容量有限、扩散条件较差,内陆厂址需要考虑的一个问题就是液态流出物中非放射性物质排放.通过分析三代压水堆内陆厂址流出物非放射性物质排放与现有法规标准要求,发现三代压水堆现有设计中工艺废液或反应堆冷却剂流出液的硼排放高达22.91 mg/L和20.15 mg/L,不能满足内陆厂址排放要求,建议增加反渗透装置进一步除硼.洗涤废液中的表面活性剂等污染物,经温排水稀释后,总排放口处能满足排放要求,但考虑环境友好,仍建议采取UV/O 3降低洗涤废液污染物排放量. 相似文献
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《给水排水》2017,(Z2)
建立河道三维水流和冷却水及含放射性液态流出物三维数学模型,对某滨河核电厂冷却水排放及含放射性液态流出物核素分布进行数值模拟研究,分析厂址排水口附近的温度场和浓度场的扩散规律。研究结果表明:方程中考虑排放口的流量动量,可合理反映扩散管周边的流态;厂址独特的河弯水力特性,使得不同扩散管布置对排放物质的稀释结果影响不大;各方案0.1℃温升线均未超过河道宽度的1/4,影响范围枯水期最大、洪水期最小,温升分布在排水口附近不均匀,但越往下游越均匀;下泄流量越大对核素的稀释作用越大,各方案稀释1 000倍时的影响长度均在3.5km左右;核素排放对上游影响很小,最大回溯距离不超过200m。这些结论可为工程设计、建设及运行提供技术服务,也对内陆核电环境问题的相关研究具有参考价值。 相似文献
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以某内陆核电厂址为例,选取90%频率环境来流作为设计基准,建立放射性液态流出物排放量与环境流量等比分配的动态排放模式,采用EFDC数学模型作为模拟手段,分析基准年逐月来流过程放射性液态流出物排放分配方式与环境水体中核素浓度变化的关系,模拟常态化实际来流过程中放射性液态流出物动态排放控制条件和水域浓度规律。应用于典型案例,提出瞬时排放量控制上限与环境流量等比例动态分配相结合的动态排放控制方式,并提出瞬时排放量上限的合理取值为3倍年均排放速率。结果表明,该动态排放控制方式可有效降低受纳水域高浓度出现时间,并实现最大峰值浓度合理控制,削弱放射性液态流出物排放对环境水体的影响。这对内陆核电厂排水管理具有重要指导意义。 相似文献
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弯道河流水域排放口布置常选择在弯道凹岸侧,以充分利用弯道环流加快稀释,然而弯道环流条件下排放口近区稀释特性与均匀流条件下存在较大差异,相关研究较少。本文在大比例尺物理模型试验中模拟复杂地形和弯道流动条件下扩散器热浮力排放近区稀释规律,采用平面激光诱导荧光(Planar Laser Induced Fluorescence,PLIF)技术进行断面浓度测量,分析了弯道环流对近区浮射流稀释扩散的影响,对扩散器出流仰角、出流水平方位角和离岸距离等进行了优化,在此基础上提出了适用于弯道水域地形条件热浮力排放的近水平非等高多喷口离岸向排放型式。研究结果对于类似弯道水域热浮力排放扩散器优化研究具有参考意义。 相似文献
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盐淡水交汇水域电厂温排水及航道取水的试验研究 总被引:6,自引:1,他引:5
笔者在珠海等火电厂排取水口物理模型试验中,把盐度作为一个独立变量进行了模拟,研究了潮汐河口盐淡水交汇水域盐度度及其密度流对排取水口布置,冷却水掺混,热量输移和温升分布的影响。发现掺混后的热水不仅可浮在受纳水体上层,也可沉至受纳水体中层或下层,并获得了原体验证。 相似文献
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Diffusers are widely-used to quickly dilute effluents in receiving water bodies. This study proposed a novel diffuser that pre-mixes effluent with ambient water before discharging and that uses the swirling jet to further enhance near-field dilution. The nozzle of the diffuser was examined in two ambient flow conditions: co-flow and counter-flow that are commonly-met in the environment such as oceans due to tidal effect. Physical experiments were first conducted in co-flow on its dilution performance and hydrodynamics, using heated water as the effluent. A 3-D CFD model was developed and calibrated the co-flow scenarios, and then used to investigate the diffuser in counter-flow. The results showed that the nozzle can effectively reduce the maximum temperature rise of the effluent by about 50 % before discharging. The swirling jet from the outlet has a larger shear area, half-width and entrainment rate, enabling the effluent to be rapidly diluted to a minimum of around 10 times at x/D = 6 in co-flow, whereas the dilution for conventional nozzles is about 1 because of the potential core. The flow amplification ratio (α) decreases gradually with increasing velocity ratio in co-flow but increases with increasing velocity ratio in counter-flow. The counter-flow reduces the water drawn into the device; however, the pre-dilution effect at the outlet remains stable. The near-field dilution in counter-flow was significantly enhanced than that in co-flow. Environmental regulations at outfalls and mixing zones can be more easily met using this novel diffuser. 相似文献
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预掺混扩散器在污水出流前掺入其周围的水进行预先稀释,可增强初始稀释度,减小混合区范围。为进一步提高扩散器的稀释水平,本文提出了一种基于环形旋转射流的新型预掺混扩散器,在进流方式以及排放形式方面另辟蹊径,并系统地研究了该扩散器射流的温度场、流场和内部压力分布。研究结果表明:该预掺混扩散器稀释性能稳定,流量放大倍比约为2.5,排口处温升极值可降低约50%,1.2倍排口直径处可降低约80%;排口后环形旋转射流无速度核心区,存在内掺混机制,极值温升及流速沿喷距呈幂函数衰减规律,具有更短的射程和更强的掺混稀释能力,对迅速缩减污染带十分有利;水头损失系数较小,约为2.4。采用该预掺混扩散器,可在离岸较近的浅水区域获得较常规扩散器深排的稀释效果,进而缩短排污输水管道、降低工程投资。 相似文献
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Abstract The paper deals with the assessment of the change in coastal water quality due to effluent discharge from a wastewater treatment plant through an outfall in the Upper Gulf of Thailand. A hydrodynamic and water quality modeling approach is used to predict the water quality level in the vicinity of the outfall when the effluent discharge and concentration levels are specified. With the continuation of effluent discharge for a one‐year period, the concentration levels of coliform bacteria and nutrients increase significantly in the vicinity of the outfall. These inferred states of seawater quality would pose hygiene risks for green mussel cultivation and affect the ecosystem due to high nutrient enrichment and eutrophication. Recommendations for improvement are put forward keeping a balance between social, economic, and engineering considerations. 相似文献