共查询到17条相似文献,搜索用时 468 毫秒
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射流曝气的气液两相流的数值模拟 总被引:7,自引:0,他引:7
射流曝气在活性污泥处理方法中起着重要的作用。采用数值模拟的方法研究自吸式单级单喷射流器中的气液两相流动状况,通过对不同长径比和喷嘴面积比的射流曝气器模型的气液两相流的计算,定量分析长径比和喷嘴面积比对射流曝气器流场和空气与工作介质流量比的影响,为进一步设计开发新型高效的射流曝气器提供参考。 相似文献
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为提高供气式低压射流曝气器中气液混合效果、提高氧传质速率,基于射流曝气器内部结构解析,提出了混合室增设分散孔板、双管进气等优化改进方案。应用FLUENT软件对射流曝气器改进前后混合室气液两相混合效果进行三维数值模拟研究,模拟结果表明,增设分散孔板可显著增加混合室湍流强度、提高气液两相混合效果,孔板设置于进气孔前更利于氧传质效率的提升;增设射流曝气器对称进气口可使气液两相在混合室内分布更加均匀,增大气液两相接触面积,促进气液两相混合。根据模拟结果加工改进型供气式射流曝气器,并进行清水充氧实验,在不同实验参数下,改进射流曝气器的标准氧传质系数、标准氧传质速率、标准氧传质效率和标准曝气效率与改进前相比分别提高19.81~20.30%、30.84%~41.87%、9.84%~25.97%、3.78%~20.56%。 相似文献
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低压供气式射流器工业化性能研究 总被引:1,自引:0,他引:1
简要介绍了低压供气式射流器的工作原理和作用,对其在氧化沟污水处理工艺中的氧利用率和动力效率等因素做了测试和分析,比较了不同水深对充氧性能的影响。结果表明,低压供气式射流曝气器氧利用率达23.17%,动力效率达2.43 kg O2/(kW.h),优于其他形式的曝气设备,可以有效降低能耗。 相似文献
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《环境工程学报》2016,(9)
选用欧拉-欧拉多相流模型和RNG k-ε湍流模型对文丘里除尘器流动特性进行数值模拟,首先对2个喷嘴时不同液体速度下的压力降和喉管液体分布情况进行模拟,并与实验值进行了比较,得到了较好的一致性;然后比较了2个喷嘴和4个喷嘴的情况下不同液体速度时文丘里除尘器的压力降和液体分布情况。模拟结果表明:欧拉-欧拉多相流模型可准确地模拟文丘里除尘器内部流场;喷嘴数量对文丘里除尘器内部的压力降和液体分布有较大影响,当相对射流深度为0.2,喉管气速为64 m·s-1,喷嘴数量由2增加为4时,压力降增加了17.17%,在喷嘴数目为4,喉管气速为74 m·s-1,液体速度为12.5 m·s-1时可使液体在文丘里除尘器内部得到较均匀的分布。 相似文献
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喷嘴角度对脱硫塔内气液两相流场的影响 总被引:1,自引:0,他引:1
提出了采用数值模拟的方法研究喷嘴角度对脱硫塔内部气液两相流场的影响。由于实际脱硫塔尺寸庞大,给实验研究带来困难且成本很高,在数值模拟平台上,分别模拟了45°、75°和-30°3种喷嘴角度布置下脱硫塔内部速度场、温度场变化以及湍流强度的分布情况。结果表明,在角度为-30°布置时速度场变化不是很剧烈,脱硫塔进出口温差比较理想,湍流强度在脱硫塔底部较大随着塔高的增加缓慢降低,这样有助于气液两相均匀混合,并控制出口烟温,有利于提高脱硫效率。 相似文献
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《环境工程学报》2017,(12)
为研究柴油机集成后处理系统的催化性能,应用CFD软件建立包括尿素水溶液分解、一氧化氮氧化和NOx选择性催化还原化学反应的数值计算模型,计算在SCR催化器上游加装DOC和CDPF催化器后不同排气温度和氨氮比时系统的催化效率。结果表明:当温度达到300℃以上时,尿素分解效率可达81%左右;NO的氧化效率基本维持在45%~60%,系统具有很好的低温催化性能,200℃时NO_x催化效率可达76.6%;当氨氮比为1.0时,大多数工况下NO_x催化效率均高于90%,最高可达98.7%。通过台架实验验证了模拟结果与实验数据绝对误差在5%以内,表明模拟计算结果可靠,可为后处理系统的设计提供理论指导。 相似文献
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An experimental study of air entrainment and oxygen transfer at a water jet from a nozzle with air holes. 总被引:3,自引:0,他引:3
An adequate supply of dissolved oxygen is important in natural rivers and in some water treatment processes. The dissolved oxygen concentration can be enhanced by entraining air bubbles in a receiving pool. When a water jet impinges a receiving pool at rest, air bubbles may be entrained and carried away below the pool free surface. This process is called plunging water jet entrainment and aeration. This paper describes an experimental study of the air entrainment rate and oxygen transfer efficiency of circular nozzles with and without air holes. In particular, the effect of varying the number, positions, and open/close status of the air holes is investigated. A negative pressure occurred depending on the air holes opened on the circular nozzles. This phenomenon affected the water jet expansion, water jet shape, air entrainment, and bubble penetration depth and, hence, the oxygen transfer efficiency. It was demonstrated that the air entrainment rate and the oxygen transfer efficiency of the circular nozzles with air holes were better than those of the circular nozzles without air holes. Therefore, adding air holes to a simple, circular nozzle could lead to a significantly increased air entrainment rate and oxygen transfer efficiency. 相似文献
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为了解决湿式氨法烟气脱硫生成不稳定亚硫酸铵((NH4)2SO3)副产物的问题,设计了以不锈钢弹簧和溶液分别作为高压和低压电极的沿面放电系统,对液相(NH4)2SO3的氧化进行了研究。空气从反应器上方进入后经放电区域形成活性物质,再由底部的曝气头鼓入溶液并与(NH4)2SO3发生反应。比较了沿面放电处理与传统曝气处理的氧化效率,考察了放电电压、载气气量和初始浓度等因素对(NH4)2SO3氧化的影响。结果表明,沿面放电对(NH4)2SO3有显著的氧化效果;优化条件下的(NH4)2SO3氧化率接近100%;溶液中(NH4)2SO4与(NH4)2SO3的浓度比小于1时有利于(NH4)2SO3的氧化。 相似文献
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Li H Chen Y Crittenden J Hand D Taylor R 《Journal of the Air & Waste Management Association (1995)》2006,56(8):1155-1166
A high-efficiency particulate air (HEPA)-carbon filtration system was developed by the Access Business Group, LLC, to reduce the indoor levels of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs). The HEPA filter removes the particle-bound PCDD/Fs, and the carbon filter removes the gaseous fraction. Because of the toxicity of PCDD/Fs, it is very difficult to handle them in the laboratory. In this study, mathematical modeling was performed to evaluate the performance of the HEPA-carbon filtration system for PCDD/Fs removal and to optimize its design and operation. The model was calibrated with experimental data conducted with toluene in a sealed room. Model simulations with four selected congeners demonstrated that it takes approximately 1 hr for the indoor air treatment system to reach the maximum removal efficiency and that the carbon air filter has a life time of 10(7) yr for dioxin removal. Given a zero emission from the HEPA filter, the overall removal efficiency is 78.7% for 2,3,7,8-tetrachloro dibenzo-p-dioxins, 89.8% for octa-chlorodibenzodioxin, 78% for tetra-chlorodibenzofuran, and 89.8% for octa-chlorodibenzofuran. The larger the mass emission from the HEPA filter, the lower the overall removal efficiency, and the larger the ratio of the filter flow rate (Q(f)) to the room flow rate (Q), the higher the overall removal efficiency. When the ratio of Q(f)/Q is 15, an overall removal efficiency of 90% can be reached for all four of the selected compounds. The removal of the four selected compounds does not change as the relative humidity increases < or = 90%. 相似文献
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流化床中污泥干燥特性 总被引:1,自引:0,他引:1
以湿污泥为原料在气固流动流化床干燥器内进行了污泥干燥特性的实验研究,考察流化风速、送风温度、联合干燥热量配比的变化对干燥强度、干燥热效率及平均传热系数的影响。实验结果表明,流化床污泥干燥最佳流化风速为1.48 m/s左右;随着流化风温的升高,干燥强度和干燥热效率逐渐增大,但增幅减小;单独的加热管干燥和流化风干燥的干燥热效率均较低,分别为33%和45%左右。在相同总输入热量下,随着内置加热管输入热量的比重越来越大,干燥热效率、干燥强度和平均传热系数均先增大后减小。 相似文献