Experimental study on secondary air mixing along the bed height in a circulating fluidized bed with a multitracer-gas method

A multitracer-gas method was proposed to study the secondary air(SA)mixing along the bed height in a circulating fluidized bed(CFB)using carbon monoxide(CO),oxygen(O_(2)),and carbon dioxide(CO_(2))as tracer gases.Experiments were carried out on a cold CFB test rig with a cross-section of 0.42 m×0.73 m and a height of 5.50 m.The effects of superficial velocity,SA ratio,bed inventory,and particle diameter on the SA mixing were investigated.The results indicate that there are some differences in the measurement results obtained using different tracer gases,wherein the deviation between CO and CO_(2) ranges from 42%to 66%and that between O_(2) and CO_(2) ranges from 45%to 71%in the lower part of the fluidized bed.However,these differences became less pronounced as the bed height increased.Besides,the high solid concentration and fine particle diameter in the CFB may weaken the difference.The measurement results of different tracer gases show the same trends under the variation of operating parameters.Increasing superficial velocity and SA ratio and decreasing particle diameter result in better mixing of the SA.The effect of bed inventory on SA mixing is not monotonic.

Analysis on the Interaction between Turbulence and Secondary Circulation of the Surface Layer at Jinta Oasis in Summer

The kinetic energy variations of mean flow and turbulence at three levels in the surface layer were calculated by using eddy covariance data from observations at Jinta oasis in 2005 summer. It is found that when the mean horizontal flow was stronger, the turbulent kinetic energy was increased at all levels, as well as the downward mean wind at the middle level. Since the mean vertical flow on the top and bottom were both negligible at that time, there was a secondary circulation with convergence in the upper half and divergence in the lower half of the column. After consideration of energy conversion, it was found that the interaction between turbulence and the secondary circulation caused the intensification of each other. The interaction reflected positive feedback between turbulence and the vertical shear of the mean flow. Turbulent sensible and latent heat flux anomaly were also analyzed. The results show that in both daytime and at night, when the surface layer turbulence was intensified as a result of strengthened mean flow, the sensible heat flux was decreased while the latent heat flux was increased. Both anomalous fluxes contributed to the cold island effect and the moisture island effect of the oasis.

Shear-Flow Induced Secondary Circulation in Parallel Underwater Topographic Corrugation and Its Application to Satellite Image Interpretation

This study aims to figure out satellite imaging mechanisms for submerged sand ridges in the shallow water region in the case of the flow parallel to the topography corrugation.Solving the disturbance governing equations of the shear-flow yields the analytical solutions of the secondary circulation.The solutions indicate that a flow with a parabolic horizontal velocity shear and a sinusoidal vertical velocity shear will induce a pair of vortexes with opposite signs distributed symmetrically on the two sides of central line of a rectangular canal.In the case of the presence of surface Ekman layer with the direction of Ekman current opposite to(coincident with) the mean flow,the two vortexes converge(diverge) at the central line of canal in the upper layer and form a surface current convergent(divergent) zone along the central line of the canal.In the case of the absence of surface Ekman layer,there is no convergent(divergent) zone formed over the sea surface.The theoretical results are applied to interpretations of three convergent cases,one divergent case and statistics of 27 cases of satellite observations in the submerged sand ridge region of the Liaodong Shoal in the Bohai Sea.We found that the long,finger-like,bright patterns on SAR images are corresponding to the locations of the canals(or tidal channels) formed by two adjacent sand ridges rather than the sand ridges themselves.

Numerical Study of the Secondary Circulations in Rip Current Systems

To investigate the mechanism of secondary circulations in rip current systems, and to explore the relationship between wave conditions and secondary circulation intensity, a series of numerical experiments is performed using coupled nearshore wave model and circulation model. In these experiments, the rip currents and secondary circulations generated above barred beaches with rip channels are simulated. A comparison experiment is conducted to investigate the formation and hydrodynamics of the secondary circulations. Model results indicate that the secondary circulations consist of alongshore flows driven by wave set-up near the shoreline, part of the feeder currents driven by the wave set-up over the bars, and onshore flows at the end of the rip channel driven by wave breaking and convection. The existence of the secondary circulation barely affects the rip current, but narrows and intensifies the feeder currents. Three groups of experiments of varying incident wave conditions are performed to investigate the relationship between wave conditions and secondary circulation intensity. The velocity of the alongshore flow of the secondary circulation is sensitive to the variation of the incident wave height and water depth. It is also found that the alongshore flow intensity is in direct proportion to the alongshore variation of the wave height gradient between the bars and the shoreline.

Hyperlactemia associated with secondary hepatocellular carcinoma resection in relation to circulation stability and quality of recovery:A case report

BACKGROUND Intraoperative hyperlactatemia often affects circulatory stability,vital organ function,and postoperative recovery,poses a serious prognostic risk,and requires considerable attention from anesthesiologists.Here,we describe a case of hyperlactatemia during the postoperative resection of liver metastases after chemotherapy for sigmoid colon cancer.This did not affect the patient's circulatory stability or quality of awakening,which is rarely reported in clinical practice.We present our management experience with the aim of providing a reference for future studies and clinical practice.CASE SUMMARY A 70-year-old female patient was diagnosed with postoperative liver metastasis following chemotherapy for sigmoid colon cancer.Laparoscopic right hemicolectomy and cholecystectomy under general anesthesia were required.Metabolic disorders,primarily hyperlactatemia,often occur intraoperatively.After treatment,other indices quickly returned to normal,lactate levels decreased slowly,and hyperlactatemia persisted during the awakening period.However,this did not affect the patient's circulatory stability or awakening quality.This condition has rarely been clinically reported.Therefore,we report our management experience in order to guide clinical practice in this regard.Hyperlactatemia did not affect circulatory stability or the quality of awakening.We considered that active intraoperative rehydration avoided serious harm to the organism caused by hyperlactatemia due to insufficient tissue perfusion,while hyperlactatemia caused by decreased lactate clearance due to impaired liver function associated with surgical resection had a mild effect on the function of important organs.CONCLUSION Active intraoperative rehydration avoided serious harm to the organism caused by hyperlactatemia.Strengthening body temperature protection could improve lactate circulation.

A Method for Diagnosing the Secondary Circulation with Saturated Moist Entropy Structure in a Mature Tropical Cyclone

Under the adiabatic, axisymmetric and steady assumption, a relationship between the saturated moist entropy structure and the secondary circulation in a tropical cyclone(TC) is derived from the continuity equation. It is found that the isentropic surfaces coincide with the streamlines, and the streamfunction can be expressed with saturated moist entropy. The secondary circulation and the saturated moist entropy structure depend on each other. Thus, a method for diagnosing the secondary circulation with the structure of saturated moist entropy is proposed. The method is verified with a simulated intense idealized TC with a highly axisymmetric structure. The diagnosed secondary circulation reproduces well the moist inflow in the boundary layer and the moist updraft in the eyewall. This method facilitates secondary circulation diagnosis in theoretical or mature TCs that satisfy the adiabatic, axisymmetric and steady approximations.

INFLUENCE OF 200 hPa DIVERGENCE CIRCULATION ON THE TRACKS OF TROPICAL CYCLONES

The characteristics of 200 hPa divergent wind and velocity potential have been analysed for four kinds of tropical cyclone tracks having impact on the SOuth China Sea. It is found that the difference of monsoon circulation in 200 hPa divergence wind field may affect the medium-range movement characteristics of tropical cyclone tracks. Corresponding to the west Pacific subtropical high,the orientation of 200 hPa secondary convergence line and its extension to the west may indicate the variability of track types.The direction of tropical cyclone movement is 2 longitudes west of and parallel to the 200 hPa secondary divergence line.

距径比调整时螺旋溜槽中二次环流演变过程及颗粒分离效率预测

为研究距径比对螺旋溜槽中流场及颗粒分离过程的影响,本文基于计算流体力学方法进行数值试验。首先,系统考察距径比调整时螺旋溜槽中二次环流的纵向演变过程;其次,考察赤铁矿和石英颗粒的迁移行为,探讨颗粒运动随流体演变的变化及距径比的影响;最后,预测分离效率并查明距径比对颗粒分离过程及结果的影响机制。研究结果表明:增大距径比能更快形成整体连续的二次环流空间分布,增大中部区域的内环流速度,削弱外缘区域的内、外环流平衡速度,降低外环流径向通量的相对稳定值和波动性;距径比越大,赤铁矿向外迁移量越多,但在r=100 mm处,迁移趋向平衡,在中部形成富集,石英在r=100 mm以外区域的向外迁移量不断升高,石英和赤铁矿富集区的位置差异扩大;分离效率预测值与距径比呈正相关,当距径比为0.8时在第3.0圈末最大分离效率可达75.03%,最佳截矿器位置在94 mm处,预测结果与二次环流演变特性及颗粒迁移规律相吻合。

低负荷下CFB锅炉二次风优化对NO_(x)排放影响的数值模拟

为控制循环流化床(circulating fluidized bed,CFB)锅炉低负荷下NO_(x)的原始排放,以某350 MW超临界CFB锅炉为研究对象,基于计算颗粒流体力学(computational particle fluid dynamics,CPFD)方法对40%负荷下燃烧过程进行数值模拟。分析了不同二次风角度、新增二次风量对NO_(x)排放的影响。结果表明:随着射流角度的减小,炉膛出口NO浓度逐渐降低,CO浓度无明显增加。部分二次风上移后炉膛密相区氧浓度降低,不完全燃烧增加,还原性氛围增强,抑制了NO的生成。当新增风量从10%增加到30%时,NO排放浓度降低了17.2%。但随着比例的进一步提高,炉膛密相区的缺氧环境造成燃烧效率下降,温度大幅降低。因此,在不影响燃烧的前提下可以通过提高新增二次风比例来降低NO的原始排放浓度。

皖南山区一次暴雪过程地转适应锋生条件分析

地转适应是形成皖南山区地形静止锋且区别平衡锋的另一种锋生机制,而地形静止锋常造成皖南山区局地灾害性天气。因此,开展地转适应锋生条件分析研究对于认识山地地形如何造成灾害性天气有重要意义。以2022年2月22日地形静止锋导致皖南山区暴雪过程为例,利用地面气象观测资料、新一代多普勒天气雷达(CINRAD/SA)基数据资料及欧洲中期天气预报中心ERA5再分析资料,采用雷达三维风场反演技术,计算此次暴雪过程的锋生函数。结果表明:(1)此次锋生过程,东北气流入流增强,流函数梯度增大,造成皖南山区背风坡山脚(30.5°—31.0°N)之间流体密度不连续,在其前沿狭窄区内出现地转适应锋生,随即出现了尺度小、呈纬向分布的局地暴雪天气;地转适应锋生和暴雪天气均发生在中低层为稳定大气层结的湿对称不稳定区内。(2)分析锋生函数及相关因子可见,垂直运动倾斜项对地面锋生贡献占主导作用,水平变形项和辐合项锋生贡献相对很小,说明此次地转适应锋生主要是地面上升运动位温垂直输送作用的结果,非风场形变引起。(3)雷达反演的中尺度风场可见,在风场非平衡状态向地转平衡状态调整的过程中,地形强迫下坡风抬升激发锋区上空1.5~3.0 km高度上的大气中低层出现很强的次级环流,导致在地面冷区冷平流增强降温,地面暖区上空因暴雪降水凝结潜热释放的非绝热加热导致增温,使得锋区位温梯度增大,出现锋生现象。

不同频次海温强迫对台风“利奇马”模拟的影响

基于WRF气象模式,利用不同时间频次的海温强迫场对2019年超强台风“利奇马”个例开展模拟研究。结果表明:不同时间频次海温强迫对台风“利奇马”路径模拟的影响较小,而对台风强度和结构的模拟有较大影响。高频海温强迫场相较于日平均海温场保留了海温与台风相互作用之前的信号,使其在台风路径上的暖涡更暖,导致模拟的台风强度更强,特别是在快速增强阶段与中国气象局台风最佳路径数据更为接近。通过对台风过程中的热力和动力过程分析发现,高频海温强迫场会使更多的水汽进入台风中心,释放凝结潜热,增强台风次级环流。对流增强使得内核区域下沉气流增强,进而加强台风暖心,导致中心气压降低,台风增强;同时,入流的增强使得更多的涡度和角动量向台风中心输送,台风结构紧致,平均切向风增大,台风增强。

基于欧拉-拉格朗日方法的流化床配风比例对炉膛磨损的数值模拟研究

循环流化床锅炉作为一种高效清洁煤燃烧技术已被广泛使用。为了探明因磨损而导致的流化床异常停机、泄漏等问题,本文基于欧拉-拉格朗日离散方法对冷态下的气固循环流化床炉膛内气固两相流动进行数值模拟计算,通过对比三种不同一、二次风比例下的炉膛水冷壁磨损情况、颗粒堆积情况以及壁面剪切应力的波动性,发现较大的配风比例会导致流化床炉膛的整体磨损量减小,壁面剪切应力波动性减小,主要原因是合理地提高一次风量可以提高锅炉燃烧效率,使炉膛内颗粒燃烧更完全,减少了煤料颗粒在炉膛内停留堆积的数量,颗粒分布更均匀,从而减少了炉膛内颗粒碰撞冲蚀磨损的发生。

一次暴雨过程的锋生特征及风场演变分析

本文利用ECMWF ERA-INTERIM(0.25°×0.25°)再分析资料和FY-2H卫星云顶亮温资料,通过计算锋生函数、非地转风、水平风切变强度的分布与暴雨的关系,对2020年7月5—7日江苏一次暴雨过程的成因进行了诊断分析。结果表明,强降水区中低层锋生、中高层锋消。850 hPa锋生变化能反映出对暴雨的影响,散度项、变形项对锋生为正贡献,变形项、倾斜项与总锋生变化趋势基本一致,散度锋生始终伴随整个降水过程,暴雨最强阶段是由倾斜锋生叠加在水平锋生上作用的结果。锋生加强了风场的非地转性,并强迫出锋面次级环流,非地转风的散度形成次级环流上升支。对流层低层,锋生强度随急流发展同步增强。200 hPa高空急流经向v场变化与暴雨强度演变趋势正相关:暴雨开始阶段,v场增大,降水增强;当高空急流v场最大时,暴雨最强;暴雨减弱结束阶段,高、低空v场减小,北风增大,高空西南风急流右后方次地转现象消失,转为超地转西南风。

Characteristics of Secondary Circulations in the Convective Boundary Layer over Two-Dimensional Heterogeneous Surfaces

Large-eddy simulations are conducted to investigate the impacts of the scale of chessboard-like heteroge- neous surface heating and the background wind on secondary circulations （SCs） in the convective boundary layer （CBL）. When the wind blows along the diagonal of the chessboard pattern, the cases with different heterogeneity length scales （λ = 1.2, 2.4, and 4.8 km） and weak background wind （U = 2.5 m s-1） suggest that there exists a threshold for the roll-like SCs, which is satisfied when the heterogeneity length scale is 1.6 times the boundary layer height （λ = 1.6zi）. During the CBL development, the SC intensity increases before this threshold is met, whereas it decreases thereafter. The cases with different background wind speeds （U = 2.5, 5.0, and 10.0 m s-1） and relatively large heterogeneity length scale （λ = 4.8 km） show that the SCs are strengthened by larger wind speeds when the heterogeneity length scale is so large that the threshold cannot be met during the CBL development. Another case with wind direction along neither the diagonal nor the side of the chessboard pattern shows that the roll-like SCs can still be triggered, but the roll axes are orientated along the diagonal of the chessboard pattern rather than along the wind direction.

Diagnosis of the Secondary Circulation of Tropical Storm Bilis(2006) and the Effects of Convective Systems on Its Track

We diagnose characteristics of the quasi-balanced flow and secondary circulation（SC） of tropical storm Bilis（2006） using the potential vorticity（PV）-ω inversion method.We further analyze how secondary steering flows associated with mesoscale convective systems affected the track of tropical storm Bilis after it made landfall.The quasi-balanced asymmetric and axisymmetric circulation structures of tropical storm Bilis are represented well by the PV-w inversion.The magnitude of the nonlinear quasi-balanced vertical velocity is approximately 75%of the magnitude simulated using the Weather Research and Forecasting（WRF） model.The SC of Bilis（2006） contained two strong regions of ascending motion,both of which were located in the southwest quadrant of the storm.The first（150-200 km southwest of the storm center） corresponded to the eyewall region,while the second（approximately 400 km southwest of the storm center） corresponded to latent heat release associated with strong precipitation in major spiral rainbands.The SC was very weak in the northeast quadrant（the upshear direction）.Dynamical processes related to the environmental vertical wind shear produced an SC that partially offset the destructive effects of the environmental vertical wind shear（by 20%-25%）.This SC consisted of upward motion in the southwest quadrant and subsidence in the northeast quadrant,with airflow oriented from southwest to northeast at high altitudes and from northeast to southwest at lower levels.The inverted secondary zonal and meridional steering flows associated with continuous asymmetric mesoscale convective systems were about-2.14 and-0.7 m s^（-1）,respectively.These steering flows contributed substantially to the zonal（66.15%） and meridional（33.98%） motion of the storm at 0000 UTC15 July 2006.The secondary steering flow had a significant influence on changing the track of Bilis from southward to northward.The direction of the large-scale meridional steering flow（3.02 m s^（-1）） was opposite to the actual meridional motion（-2.06 m s^（-1））.

电解铝烟气二次循环净化深度除氟工艺改造及应用

针对电解铝烟气净化系统氧化铝投料均匀性差、清洁度低、除尘器运行效率低、载氟氧化铝载氟率低、载氟氧化铝易结壳及投料不均匀等行业共性问题,采取了溢流式投料溜槽、新型一次投料分料箱结构、新型文丘里反应器等新技术及工艺装备新设计、开发措施,完成了烟气净化一次投料、二次投料系统升级改造,载氟氧化铝的载氟率提高了51.28%、烟气中氟化物排放浓度降低了88.98%,效果显著。

Thermal Wind Imbalance along the Curved Streamline of the Secondary Circulation in Tropical Cyclones

The thermal wind balance in tropical cyclone(TC)eyewalls has been controversial for decades.This study reveals the relationship between the acceleration and curvature on the TC secondary circulation streamline,providing a way to judge thermal wind balance or imbalance in TCs from a simple but clear perspective.According to the relationship between the curvature and acceleration on the streamline,the vertical and radial components of the acceleration cannot be zero simultaneously on the streamline curve,implying that the thermal wind imbalance corresponds to the curvature of the streamline.On the regular scales of TCs,we discuss the conditions of the thermal wind balance approximation and find that the conditions become more stringent with increasing altitudes.In the TC secondary circulation,as an indication of thermal wind imbalance,gradient wind imbalance can be found in the low-level eyewall since there is usually a large curvature when the inflow in the low-level eyewall turns into updrafts sharply.Additionally,gradient wind imbalance also appears at the top level of TC eyewalls because the stringent conditions are too easily broken there.

荧光示踪剂在监测二级水浓缩倍数中的应用

文章针对反渗透海水淡化二级产品水作为循环冷却系统补充水时,水中离子含量低、药剂干扰大,导致浓缩倍数计算结果偏差大的问题,采用添加荧光化合物的方法监测系统浓缩倍数,并探讨了荧光示踪剂1,3,6,8-芘四磺酸钠在去离子水中的荧光特性,考察了杀菌剂、阻垢缓蚀剂对荧光特性的影响;采用静态阻垢性能试验方法,模拟冷却系统条件,综合评价了浓缩条件变化对其荧光特性的影响。结果表明,1,3,6,8-芘四磺酸钠荧光信号稳定,能够有效监测循环冷却系统浓缩倍数变化。

EFFECT OF THE THERMAL FORCING ON THE SECONDARY CIRCULATION OF TYPHOONS

A non-dimensional secondary circulation equation for typhoons has been derived and then 11-yr com- positing typhoon data were used to estimate the thermally forced secondary circulation.The main results have been obtained as follows: (1)The diabatic heating and Cu vertical heat mixing are major thermal forcing factors.They have the same magnitude of order.(2)The effects of eddy flux and Cu horizontal mixing of heat are of minor im- portance.(3)Ekman pumping and Cu vertical heat mixing cooperatively work.This feedback process is favorable for the enhancement of the secondary circulation of typhoons.

热力站二级网支路分解循环泵供热技术分析与研究

为减少城市能耗、提高供热质量以及保护环境,对供热技术进行深入研究,分解循环泵应运而生。文章分析了供热原理,研究了该供热系统的核心技术,包括局部支路混水、支路流量调节,并总结了运行全新供热系统的注意事项。