河道型水库干支流交汇段水力特性数值分析

以典型河道型水库库区主流与支流交汇段几何尺寸与来流条件为参照,建立了三维概化数学模型并开展多情景数值分析,以揭示不同交汇角对干支流交汇段关键水力特性变化的影响.重点研究了交汇角α分别为30°,60°,90°,120°,150°的5种工况,计算结果表明:在不同交汇角条件下均存在紊动能高值集中区域,且紊动能与交汇角大小存在正相关关系,即随着交汇角增大,紊动能峰值区域的面积及峰值大小显著增大;不同交汇角条件下床面切应力最大值均由交汇口向支流上游沿程递减,而当α<90°时断面流速变异系数沿程先增大后减小,当α≥90°时断面流速变异系数沿程减小;另外,当α<90°时,床面切应力和断面流速变异系数与交汇角大小存在负相关关系,而当α≥90°时,这2个特性指标随着交汇角增大而递增.     

南方8种森林地表死可燃物在平地无风时的燃烧蔓延速率与预测模型

【目的】研究Rothermel林火蔓延速率预测模型及另外2种以Rothermel模型为核心的蔓延速率预测模型对南方8种典型森林地表死可燃物的适用性,为林火蔓延速率预测提供理论支撑和指导。【方法】以南方地区8种典型速率地表死可燃物为对象,根据研究对象的野外实际条件,在东北林业大学帽儿山实验林场风洞实验室内,构建不同可燃物床层含水率、载量及高度的可燃物床层,每种可燃物在平地无风条件下进行36次点烧试验,共288次点烧,记录每种可燃物类型不同配比条件下的蔓延速率。通过直接使用Rothermel模型、重新估计Rothermel模型参数、对Rothermel模型形式改进后自建模型的对比,得到最合适的预测模型。【结果】 1)平地无风条件下,南方8种典型森林地表死可燃物床层最大蔓延速率为0.55 m ·min -1 ,平均蔓延速率由大到小依次为:华山松、云南松、毛竹、柳杉、杉木、马尾松、麻栎及青冈栎。2)直接使用Rothermel模型预测的林火蔓延速率误差较大,平均绝对误差为0.18 m ·min -1 ,平均相对误差为70.0%。3)重新估计参数后的Rothermel模型及自建模型,预测的可燃物蔓延速率精度显著提高,平均绝对误差分别为0.04、0.037 m ·min -1 ,平均相对误差分别<18%、16.45%。4)重新估计参数的Rothermel模型与自建模型的预测误差的差异不显著,其中自建模型的预测值与实测值的 R 2 变化在0.71~0.90,平均为0.80。【结论】对南方8种典型森林的地表死可燃物类型,在平地无风条件下,重新估计参数的Rothermel模型及自建模型的预测精度相近,但自建模型可能更简单易用,可预测平地无风条件下可燃物地表火蔓延速率。     

覆膜槽沼气规模化干法发酵技术与装备研究

研制了以覆膜槽生物反应器(MCT)为核心的沼气规模化干法发酵系统。该系统采用"软管充气膨胀压力密封联接装置",实现了反应器厌氧―好氧状态的快捷转换,解决了大规模快速进出料的问题,并可直观判断反应器中沼气的存留量,操作简便、安全;利用固态有机物料好氧发酵产生的生物能获得中温厌氧发酵所需温度,并辅以高效的保温措施,无需外加热源,即可维持厌氧发酵的中温(35～42℃)运行;采用单元化设计,通过增减启动厌氧反应器的数量,可满足不同用气量的要求。建设了生物反应器容积为180 m3的沼气干法发酵中试工程。该中试工程容积产气率为0.598 m3/(m3.d),沼气甲烷含量55%～60%。     

Mathematical Model of Flow Process in 40t/h Pyroflow Circulating Fluidized Bed Boiler

A mathematical model is presented to describe the fluiddynamics processes for the combustion system of 410t/h Pyroflow CFB boiler.A core annulus structure with solid dispersion from core to annulus is considered,and the influence of coal particles fragmentation,attrition and broad size distribution of feeding coal and bed inventory on hydrodynamics is specially taken into account.The simulation results show that the CFB boiler has good hydrodnamic characteristics and high hot cyclone efficiency.     

多孔高分子载体固定化微生物厌氧流化床处理低浓度废水的研究

本文报道用厌氧流化床反应器处理低浓度有机废水的可行性研究结果。采用多孔高分子载体固定厌氧微生物和流态化技术强化传质过程,可克服低浓度有机废水甲烷化能力低的障碍。实验表明,在３５±１℃条件下,处理ＣＯＤ浓度为１６００ｍｇ／Ｌ的人工葡萄糖废水,床层最优膨胀率为５０％,容积有机负荷率为１９．２ｇＣＯＤ／（Ｌ·ｄ）,ＣＯＤ去除率达７０％;处理ＣＯＤ浓度为２２０～２５０ｍｇ／Ｌ的城市污水,容积有机负荷率为２．４～２．６ｇＣＯＤ／（Ｌ·ｄ）,ＣＯＤ去除率为５４％～５６％。     

甘薯原料气升式生物反应器发酵生产单细胞蛋白

以甘薯为原料,采用少孢根霉ＡＳ３．４３９２与树状假丝酵母混合发酵工艺,在无筛板、带一块和带二块筛板的气升式生物反应器中发酵４８ｈ后的干基粗蛋白的含量分别为４６．４％、４７．１％、４７．７％。试验结果表明,气升式生物反应器的发酵结果优于机械搅拌式生物反应器,而带筛板的气升式生物反应器又优于不带筛板的气升式生物反应器。在氧传递性能考察中,发现气升式生物反应器内加装筛板可以有效地强化氧传递     

利用间歇浸没式植物生物反应器培养金钗石斛种苗

以金钗石斛（Dendrobium nobide Lindl.）原球茎为材料,利用间歇浸没式植物生物反应器进行金钗石斛组培快繁的研究。通过优化浸没频率、接种量和培养基蔗糖浓度,获得最佳的培养条件为：浸没频率5 min/8 h、接种量10 g·L-1、蔗糖浓度20 g·L-1,并与传统的固体培养比较,反应器培养在组培苗的生长形态、增殖倍数和有效成分上都明显优于固体培养。利用间歇浸没式植物生物反应器进行金钗石斛种苗培养,为金钗石斛种苗的高效率、低成本的生产提供了一种新的方法。     

污水芦苇碎石床处理出水养鱼回用技术研究

通过直接建造在鱼塘内的芦苇碎石床处理城市污水后,再抽鱼塘底层水回流到芦苇碎石床上进行再处理的试验研究表明,这种处理可使鱼塘水质达到卫生养鱼的水质标准。这一回用技术是安全可行的,有较好的经济效益。     

Observations on the conditioning of filter bed in hypersaline aquaria

The nitrifying activity of the filter bed of aquaria was monitored in hypersaline conditions. Salinity was raised in 5 ppt steps from normal sea water to 126 ppt in a course of 35 and 41 days. Twenty grey mullet fry (Chelon labrosus and Mugil cephalus) were used in two 53 l aquaria. Daily monitoring of total ammonia–nitrogen (TAN), nitrite, nitrate ions, and pH was performed. After an initial peak of TAN (0.65 mg/l), total ammonia stabilized at safe low levels (0–0.2 mg/l). Nitrite exhibited more peaks at levels of about 10 mg/l, lasted for 3–8 days but they also subsided to almost zero afterwards. Nitrate finally stabilized at levels around 100 mg/l. The water was alkaline, with pH fluctuating in the region of 8.2–8.8. These findings indicate that the filter bed may be effectively conditioned for hypersalinity and that fish may be safely maintained in the aquaria.     

Evaluation of three types of structured floating plastic media in moving bed biofilters for total ammonia nitrogen removal in a low salinity hatchery recirculating aquaculture system

Three different commercially available structural plastic media were evaluated in triplicate in moving bed biofilters under low salinity (11–12 ppt) warm water culture conditions and two different feed loading rates. The culture system consisted of nine separate modules that include a double drain fish culture tank paired to a moving bed biofilter. The biofilters were filled with 0.11 m³ of one of three different types of floating plastic structured media. The three types of media evaluated were K1 kaldnes media, MB3 media, and AMB media. Volumetric total ammonia nitrogen (TAN) removal rates (g TAN removed/m³ media-day), TAN removal efficiency, and biofilm kinetic constants, K_i (h⁻¹) were determined for the three media types at two different daily feed load rates of 3.5 and 8.2 kg feed/m³ media. The feed provided was a 4.8 mm slow sinking marine grower diet pellet (45% protein, 17% fat). Average (±standard deviation, SD) volumetric TAN removal rates (VTR) at the lower feed load for the three media types were 92.2 ± 26.3, 86.1 ± 27.5, and 82.5 ± 25.9 for the MB3, AMB, and K1 kaldnes media, respectively. At the higher feed load the average VTR for the three media types was 186.4 ± 53.7, 172.9 ± 47.8, and 139.9 ± 38.9 for the MB3, AMB, and K1 kaldnes media, respectively. Influent TAN concentrations varied by the feed load rate and ranged from 0.55 to 0.93 mg/L and 0.83 to 1.87 mg/L for the low and higher feed loads, respectively. The percent TAN removal rates for the MB3 media was the highest of the three media types at both the low and high feed load rates averaging 12.3% and 14.4%, respectively. The MB3 media was selected for use in the moving bed biofilters because of the greater VTR and removal efficiency results for use in the 0.11 m³ moving bed biofilters of the hatchery recirculating aquaculture system.