穿流-刚柔组合桨强化固液两相的悬浮行为

采用双向流固耦合计算方法对搅拌槽内刚性桨(RDT-PBDT)、刚性组合桨(R-RDT-PBDT)、刚柔组合桨(RF-RDT-PBDT)、穿流-刚性组合桨(PR-RDT-PBDT)以及穿流-刚柔组合桨(PRF-RDT-PBDT)体系中的固液两相悬浮特性和桨叶总变形量、等效应力进行了研究。结果表明,在相同功耗下,PRF-RDT-PBDT的最大变形量分别是RDT-PBDT、R-RDT-PBDT、RF-RDT-PBDT、PR-RDT-PBDT的1.984×106倍、1.247×103倍、1.169倍、1.041×103倍。PRF-RDT-PBDT的应力大于RDT-PBDT、R-RDT-PBDT、RF-RDT-PBDT的,比PR-RDT-PBDT的应力分布更均匀。PRF-RDT-PBDT体系的固体颗粒最大Uz/Utip值和最大ε/D2N 3值分别比RDT-PBDT、R-RDT-PBDT、RF-RDT-PBDT和PR-RDT-PBDT体系提高了53.08%和80.84%,38.03%和28.42%,22.14%和20.16%,10.85%和5.725%。PRF-RDT-PBDT能够增大与流体之间的相互耦合作用,增大固体颗粒的轴向速度,提高体系的湍动能耗散率,减小搅拌槽底部固体颗粒的堆积程度,提高固体颗粒的悬浮程度。     

刚柔组合搅拌桨强化流体混合的流固耦合行为

传统刚性搅拌桨通过对流体的剪切作用实现能量的传递,而刚柔组合搅拌桨可通过其多体运动行为强化能量传递。基于搅拌桨桨叶与流体之间的耦合运动作用,结合ANSYS Workbench仿真平台,采用双向流固耦合方法,模拟计算了刚性搅拌桨与刚柔组合搅拌桨桨叶的等效应力和总变形量,研究了流场的宏观结构;并通过测定混合时间和计算搅拌桨功耗对比分析了两种不同搅拌体系的混合行为。结果表明:刚柔组合搅拌桨使体系的混合时间缩短了近32%,搅拌桨功耗下降了7%,其桨叶尖端的变形量是刚性搅拌桨的10⁵倍,其应力比刚性搅拌桨增加了83%;与刚性搅拌桨相比,刚柔组合搅拌桨在流固耦合作用下对流体的作用力更大,能够更好地传递能量,增强流体运动,强化流体混合。     

刚柔组合搅拌桨强化搅拌槽中流体混沌混合

搅拌槽内普遍存在着两种不同类型的混合区域：混沌混合区和规则区。增大混沌混合区,是提高流体混合效率、降低搅拌过程能耗的重要途径。而合理设计搅拌桨有助于流体形成适宜的流动状态,实现混沌混合。柔性体与刚性体组合,可设计出具有多体运动行为的刚柔组合搅拌桨,可强化流体混沌混合行为。结合Matlab 软件,实验研究了双层桨搅拌槽内自来水体系的最大Lyapunov指数（LLE）和多尺度熵（MSE）的变化规律,对比分析了刚性桨和刚柔组合桨两种桨叶对流体混沌混合的影响。结果表明,刚柔组合桨强化流体的运动特性,使更多流体进入混沌混合状态。在转速为210 r·min^-1时,流体的混沌混合达到最佳状态,刚性桨体系的LLE为0.041,而刚柔组合桨体系的LLE为0.048;刚柔组合桨可有效耗散能量,使整个槽体的能量分布均匀,刚柔组合桨在150 r·min^-1时的多尺度熵率与刚性桨在210 r·min^-1时基本相近;刚柔组合桨体系的混合时间均低于刚性桨体系,在转速为120 r·min^-1时,刚柔组合桨使流体的混合时间缩短了26%左右。刚柔组合桨可改变流场结构和能量耗散方式,强化流体混沌混合,实现高效节能操作。     

变频刚柔搅拌反应器强化锰矿浸出及除铁过程

传统锰矿浸出过程采用刚性搅拌反应器,存在矿粉悬浮效果差、锰矿利用率低、浸出液中铁含量较高的问题。本文采用变频刚柔搅拌反应器强化锰矿的浸出过程,实验对比分析了不同桨叶类型、搅拌桨操作方式和变频间隔时间对锰矿浸出效果、搅拌功耗的影响,同时分析了变频刚柔桨耦合空气射流在除铁过程的效果。结果表明,变频刚柔桨通过柔性钢丝绳对流体的扰动作用以及变频操作对稳定流场的更新作用,提高浸出液中Mn²⁺含量;同时,由于体系变频操作的频率变化,降低了搅拌功耗。相同功耗下,刚柔组合桨体系浸出液中Mn²⁺含量相对于刚性桨体系提高了10.8%;相同转速下,刚柔组合桨体系在浸出过程的功率消耗相对于刚性桨体系提升了25.4%。变频间隔时间为30min时,变频刚柔桨体系浸出液中Mn²⁺含量相对于刚柔组合桨体系降低了2.17%,但相应搅拌功耗降低了28%。调节体系pH后,采用变频刚柔桨耦合偏心空气射流操作,可有效降低浸出液中Fe²⁺含量。在通气60min后,浸出液中Fe²⁺浓度已至较低水平,低于0.15mg/L。     

搅拌槽内气液两相混沌混合及分散特性

传统Rushton刚性桨常应用于过程工业中搅拌反应器内的气液分散过程,但由于桨叶背后易形成较大的气穴,气液混合效果较差。为了提高搅拌槽内气液两相的混合效果,提出了一种刚柔组合桨强化气液两相的分散过程。利用LabVIEW软件处理刚性桨和刚柔组合桨体系中气液混合过程的压力脉动信号,通过Matlab软件编程计算最大Lyapunov指数（LLE）,分析气液混合体系的混沌混合行为,同时,对刚性桨和刚柔组合桨体系中的相对搅拌功耗、整体气含率、局部气含率进行测量。结果表明,在功耗为170 W,通气量为10 m³·h^-1条件下,与刚性桨相比,刚柔组合桨能够通过刚-柔-流的耦合作用促进桨叶能量的传递过程,提高搅拌体系的混沌混合程度,刚柔组合桨体系的LLE提高了8.89%。同时,在相同操作条件下,与刚性桨相比,刚柔组合桨能够有效提高相对搅拌功耗以及搅拌槽内的整体气含率和局部气含率,且搅拌槽内气体分散更为均匀。     

刚柔组合桨强化粉煤灰酸浸搅拌槽内固液混沌混合

传统粉煤灰提铝工艺中酸浸搅拌槽均采用刚性搅拌桨。因刚性桨卷吸能力有限，导致固体颗粒易沉槽、流体混沌混合效率低。提出刚柔组合桨强化酸浸搅拌槽中固液混沌混合行为。实验基于固含率为30%的粉煤灰-自来水体系，研究了刚柔组合酸浸搅拌槽内混沌混合特性及能量耗散规律。采用扭矩传感器采集扭矩时间序列信号，借助Matlab软件编译计算混合过程中最大Lyapunov指数和多尺度熵等混沌特性参数，以单位体积功耗表征搅拌反应器的功率特性。实验考察了搅拌桨安装离底高度、柔性片长度、柔性片宽度等因素对酸浸槽内粉煤灰混沌混合的影响，对比了刚性桨与刚柔组合桨体系的能耗差异。研究结果表明：刚柔组合桨通过柔性片的作用，能增大搅拌桨的卷吸力，进而减少固体颗粒沉槽现象，促进全槽混沌混合；在最优化条件（120 r/min，搅拌桨安装离底高度为T/4，柔性片长度为1.2H ₁、柔性片宽度为D/8）下，体系最大Lyapunov指数达到最大值0.0645，各尺度下的MSE均比其他条件更大，表明刚柔组合桨能够通过柔性片的多体运动，强化体系混沌混合，均化体系能量分布；刚性桨与刚柔组合桨的单位体积功耗随着转速的增加呈现指数规律增长。     

刚柔组合桨强化粉煤灰酸浸搅拌槽内固液混沌混合

传统粉煤灰提铝工艺中酸浸搅拌槽均采用刚性搅拌桨。因刚性桨卷吸能力有限,导致固体颗粒易沉槽、流体混沌混合效率低。提出刚柔组合桨强化酸浸搅拌槽中固液混沌混合行为。实验基于固含率为30%的粉煤灰-自来水体系,研究了刚柔组合酸浸搅拌槽内混沌混合特性及能量耗散规律。采用扭矩传感器采集扭矩时间序列信号,借助Matlab软件编译计算混合过程中最大Lyapunov指数和多尺度熵等混沌特性参数,以单位体积功耗表征搅拌反应器的功率特性。实验考察了搅拌桨安装离底高度、柔性片长度、柔性片宽度等因素对酸浸槽内粉煤灰混沌混合的影响,对比了刚性桨与刚柔组合桨体系的能耗差异。研究结果表明:刚柔组合桨通过柔性片的作用,能增大搅拌桨的卷吸力,进而减少固体颗粒沉槽现象,促进全槽混沌混合;在最优化条件(120 r/min,搅拌桨安装离底高度为T/4,柔性片长度为1.2H1、柔性片宽度为D/8)下,体系最大Lyapunov指数达到最大值0.0645,各尺度下的MSE均比其他条件更大,表明刚柔组合桨能够通过柔性片的多体运动,强化体系混沌混合,均化体系能量分布;刚性桨与刚柔组合桨的单位体积功耗随着转速的增加呈现指数规律增长。     

弹性搅拌桨强化液-液两相混沌混合及液滴分散特性的研究

传统的混合澄清槽一般采用刚性搅拌桨来实现液-液两相的混合萃取,普遍存在效率低、能耗高等问题。将一种弹性搅拌桨应用在混合澄清槽中,以强化液-液两相混沌混合及分散特性。以最大Lyapunov指数（LLE）和多尺度熵（MSE）表征体系混沌状态,以分散相液滴粒径分布、Sauter平均粒径（D₃₂）等表征分散效果,分别研究了桨叶类型（弹性搅拌桨、刚柔组合桨及刚性桨）、弹簧长度、线径、外径等因素对混沌混合效果和分散特性的影响。结果表明,相比较刚性搅拌桨和刚柔组合搅拌桨,弹性搅拌桨通过弹簧的形变和储能作用,强化了搅拌能量的传递方式,提高了分散相的分散效果,有利于液液两相的混沌混合,在搅拌转速N=200 r/min、弹簧线径为0.6 mm、弹簧相对长度为1.2、弹簧外径为7 mm时,弹性搅拌桨体系的LLE和MSE更大,且MSE值波动最强;同时,各搅拌体系内分散相平均粒径D₃₂与转速呈对数线性关系,弹性搅拌桨体系内分散相液滴尺寸更小且数量更多。     

湿法磷酸固-液体系混沌混合与浸出强化行为

湿法磷酸浸出过程中，传统刚性搅拌桨的作用方式主要是剪切作用，容易形成对称性流场结构，降低搅拌效率。实验考察了桨叶类型、离底高度、搅拌速度、柔性钢丝绳长度、柔性钢丝直径对磷矿浸出率及最大Lyapunov指数(LLE)的影响。实验结果表明：刚柔组合桨通过刚-柔-流的耦合作用，改善流场的结构，提高了流体混沌混合效果。当搅拌转速225 r/min，浸出时间120 min，离底高度h=T/4，柔性钢丝绳直径d= 0.42r，柔性钢丝绳长度L=1.3T时，刚柔组合桨的最大Lyapunov指数达到0.09071，磷矿浸出率提高了10.8%。另外，在相同的功耗(P _v=9890 W/m³)条件下，刚柔组合桨使反应器内的悬浮均匀度和渣中磷含量分别降低了40.8%和17.67%，有效地改善了晶体的形貌，提高了磷石膏的过滤性能，强化了颗粒的混合与浸出。     

长短叶片复合型刚柔桨强化搅拌槽内流体混沌混合行为

搅拌反应器中混合隔离区的存在是强化流体混合的主要障碍。打破搅拌槽中的对称性流场结构,破坏混合隔离区,可以提高流体混合效率。采用Matlab软件编程计算最大Lyapunov指数（LLE）和多尺度熵（MSE）,比较了不同桨叶类型、柔性片长度、柔性片数量和桨叶离底高度以及转速对流体混合的影响。结果表明,长短叶片复合型刚柔桨（RF-LSB）桨叶通过刚柔耦合错位连接,柔性片的形变与随机振动对流体的非稳态扰动,使流场结构不稳定性和不对称性增强,强化了流体混合效果。当柔性片数量为3,搅拌转速为90 r/min时,RF-LSB体系比刚性桨和刚柔桨体系的LLE值分别提高了20.22%和7.98%;三种体系[RF-LSB（柔性片数量为3）、刚性桨和刚柔桨体系]的混合时间（θ_m）与单位体积功耗（P_v）呈指数型关系,当P_v相同时,RF-LSB（柔性片数量为3）的θ_m最小,表明RF-LSB（柔性片数量为3）更有利于流体混沌混合。     

天然磁铁矿/UV/S2O82-对焦化废水中不同种类有机物的去除特性

以过硫酸盐（PS）为中心建立了C（天然磁铁矿）/PS、UV/PS、C/UV/PS氧化体系,分别对焦化废水生化出水进行深度处理,采用超滤膜法和有机物树脂分离方法分别对深度处理前后废水中有机物分子量分布特性及亲疏水性有机物含量变化进行了研究。研究表明：生化出水中含有较多的难降解芳香性有机物,且以分子量（M_W）<1×10³的低分子量有机物为主,其次是M_W>100×10³和10×10³～100×10³的大分子有机物。疏水酸和疏水中性组分是废水中的主体有机物,其DOC分别占总DOC的45.88%和32.09%。C/UV/PS相对C/PS、UV/PS氧化效果更好,在原水pH,铁矿石和PS的投加量分别为3 g·L^-1和2 g·L^-1,紫外光照射功率为300 W条件下,氧化90 min时COD、UV₂₅₄、DOC和色度的去除率分别为74.9%、93.5%、84.1%和80.1%。从矿化效果来看,C/UV/PS氧化体系对M_W>10×10³的大分子有机物的去除效果显著,深度处理后M_W<1×10³的有机物分子占比增加;该体系对疏水性和弱疏水性有机物去除效果较高,深度处理后亲水性有机物占比增加。     

石化中间储罐挥发性有机物排放特征与反应活性

中间储罐是石化企业的主要挥发性有机物(VOCs)排放源,对大气环境产生重要影响。本文对我国某石化企业炼化中间产物、污油、石化中间产物等中间储罐大呼吸过程进行了采样监测,分析了VOCs排放特征并建立了有机污染物图谱。基于OH自由基损失速率和最大增量反应活性法,分别量化了大呼吸过程大气反应活性和臭氧生成潜势(OFP)。结果表明,中间储罐大呼吸过程VOCs浓度高达数万毫克每立方米,单位体积物料周转量VOCs排放强度达到0.55～71.3g/m³。不同储罐排放特征差异大,炼化中间产物及污油储罐VOCs组成以烷烃为主,石化中间产物储罐VOCs以烯烃和芳香烃为主;C₃～C₇烷烃、C₃～C₄烯烃、苯、甲苯和丙酮等是首要污染物。中间储罐大呼吸损耗气具有较高大气光化学反应活性和臭氧生成潜势(OFP),OH自由基损失速率常数接近1.43×10⁴～2.37×10⁶s^-1,OFP达到2.84×10⁵～7.53×10...     

Kinetics of xylose dehydration into furfural in acetic acid

In this paper kinetics of xylose dehydration into furfural using acetic acid as catalyst was studied comprehensively and systematical y. The reaction order of both furfural and xylose dehydration was determined and the reaction activation energy was obtalned by nonlinear regression. The effect of acetic acid concentration was also investi-gated. Reaction rate constants were galned. Reaction rate constant of xylose dehydration is k1 ? 4:189 . 1010 ?A.0:1676 exp ?108:6.1000RT . ., reaction rate constant of furfural degradation is k2 ? 1:271 . 104?A.0:1375 exp?63:413.1000RT . and reaction rate constant of condensation reaction is k3 ? 3:4051 . 1010?A.0:1676 exp?104:99.1000RT .. Based on this, the kinetics equation of xylose dehydration into furfural in acetic acid was set up according to theory of Dunlop and Furfural generating rate equation is dd?F.t ? k1?X.0e?k1t?k2?F.?k3?X.0e?k1t?F.. ? 2015 The Chemical Industry and Engineering Society of China, and Chemical Industry Press. Al rights reserved.     

Effects of Temperature and Strain Rate on the Plastic Deformation of Fully Dense Polycrystalline Y1Ba2Cu3O7−x Superconductor

The knowledge of the steady-state stress for plastic deformation as a function of temperature and strain rate is essential for hot-forming superconducting material into commercially useful shapes. In this paper, results are presented on the experimental determination of the rheology of fully dense polycrystalline Y₁Ba₂Cu₃O_7−x superconducting material at temperatures ranging from 750° to 950°C and strain rates of 10⁻⁴, 10⁻⁵, and 10⁻⁶ s⁻¹. The data are best fitted by a power law: ε(s⁻¹)=8.9 × 10⁻¹⁷. (s⁻¹) σ^2.5 (Pa) exp [−2.01 × 10⁵(J·mol⁻¹)|RT]. X-ray analysis shows that the superconducting material retains its phase composition after nearly 70% total strain of the sample. A strong anisotropy in the resistivity of the deformed samples is observed because of the development of a preferred orientation of the a or b axis of Y₁Ba₂Cu₃O_7−x orthorhombic perovskite single crystals perpendicular to the principal maximum compressive stress.     

酸功能化离子液体催化合成仲丁醇的反应动力学(英文)

The acid-functionalized ionic liquid ([HSO3Pmim]HSO4) was synthesized by a two-step method. Nuclear magnetic resonance (NMR) and Fourier transform infrared spectroscopy (FT-IR) show that the synthesis method is feasible and high purity of ionic liquid can be obtained. Using [HSO3Pmim]HSO4 as the catalyst, we studied the reaction kinetics of synthesizing sec-butyl alcohol from sec-butyl acetate and methanol by transesterification in a high-pressure batch reactor. The effects of temperature, initial molar ratio of methanol to ester, and catalyst concentration on the conversion of sec-butyl acetate were studied. Based on its possible reaction mechanism, a ho-mogeneous kinetic model was established. The results show that the reaction heatΔH is 10.94 × 103 J·mol?1, so the reaction is an endothermic reaction. The activation energies Ea+and Ea?are 60.38 × 103 and 49.44 × 103 J·mol?1, respectively.     

Reaction kinetics for synthesis of sec-butyl alcohol catalyzed by acid-functionalized ionic liquid

The acid-functionalized ionic liquid ([HSO3Pmim]HSO4) was synthesized by a two-step method. Nuclear magnetic resonance (NMR) and Fourier transform infrared spectroscopy (FT-IR) show that the synthesis ...     

Process optimization of an industrial acetic acid dehydration progress via heterogeneous azeotropic distillation

The simulated process model of the HAc dehydration process under actual overloaded condition was conducted by amending the model of standard condition in our previous work using the process data collected from actual production. Based on the actual process model, the operation optimization analysis of each plant(HAc dehydration column, decanter and NPA recycle column) was conducted using Residue Curve Maps(RCMs),sensitivity analysis and software optimization module. Based on the optimized parameters, the influence of feed impurity MA and the temperature of decanter on the separating effect and energy consumption of the whole process were analyzed. Then the whole process operation optimizing strategy was proposed with the objective that the total reboiler duty Q Total of C-1 and C-3 reaches the minimum value, keeping C-1 and C-3 at their optimized separation parameters obtained above, connecting all the broken recycle and connection streams, and using the temperature of D-1 as operation variable. The optimization result shows that the total reboiler duty Q Total of the whole process can reach the minimum value of 128.32 × 10~6 k J·h~(-1) when the temperature of decanter is 352.35 K, and it can save 5.94 × 10~6 k J·h~(-1), about 2.56 t·h~(-1) low-pressure saturated vapor.     

In-situ Polymerization-modification Process and Foaming of Poly（ethylene terephthalate）

Most of traditional linear poly（ethylene terephthalate）（PET） resins of relatively low molecular mass and narrow molecular mass distribution have low melt strength at foaming temperatures, which are not enough to support and keep cells. An in-situ polymerization-modification process with esterification and polycondensation stages was performed in a 2 L batch stirred reactor using pyromellitic dianhydride（PMDA） or pentaerythritol（PENTA） as modifying monomers to obtain PETs with high melt strength. The influence of amounts of modifying monomers on the properties of modified PET was investigated. It was found that the selected modifying monomers could effectively introduce branched structures into the modified PETs and improve their melt strength. With increasing the amount of the modifying monomer, the melt strength of the modified PET increased. But when the amount of PENTA reached 0.35% or PMDA reached 0.9%, crosslinking phenomenon was observed in the modified PET. Supercritical carbon dioxide（ScCO2） was employed as physical foaming agent to evaluate the foaming ability of modified PETs. The modified PETs had good foaming properties at 14 MPa of CO2 pressure with foaming temperature ranging from 265 °C to 280 °C. SEM micrographs demonstrated that both modified PET foams had homogeneous cellular structures, with cell diameter ranging from 35 μm to 49 μm for PENTA modified PETs and 38 μm to 57 μm for PMDA modified ones. Correspondingly, the cell density had a range of 3.5×107cells·cm 3to 7×106 cells·cm 3for the former and 2.8×107cells·cm 3to 5.8×106cells·cm 3for the latter.     

沉淀-微滤组合工艺处理模拟含碘放射性废水

采用实验室规模的沉淀与膜分离组合工艺处理模拟含放射性I-废水,初始I-浓度约为5 mg·L^-1,Na₂SO₃投加量为40 mg·L^-1,CuCl投加量为260 mg·L^-1。分析考察了不同水温条件下的除碘效果及其他水质参数变化情况和两个膜通量4.17×10^-6 m·s^-1和8.33×10^-6 m·s^-1运行条件下的膜污染情况。运行时间均为168 h,处理含碘离子的废水水量为1540 L。两个膜通量在各自运行期间,平均去除率为94.8%,出水水质较稳定,但是出水的Cu（Ⅱ）离子含量较高,需要增加后续除铜工艺;最终膜比通量分别降至初始膜比通量的65.0%和55.0%,膜组件经物理和化学清洗后SF值分别恢复至初始SF值的90.0%和79.0%。反应结束后两次试验的CF（浓缩倍数）平均值为2.02×10³,试验产生的污泥体积较小。     

Deformation and toughness of polymeric systems: 3. Influence of crosslink density

In part 1 of this series the phenomenon of a critical ligament thickness (ID_c) below which brittle polymers become ductile was investigated for polystyrene (PS). Using the thermoplastic polystyrene-poly(2,6-dimethyl-1,4-phenylene ether) (PS-PPE) model system, it was demonstrated in part 2 of this series that the absolute value of ID_c as well as the maximum toughness (i.e. maximum strain to break) was dependent on the network density of the polymer used. In this study the toughness and ID_c of crosslinked thermosetting polymers were investigated using epoxides based on the diglycidyl ether of bisphenol A as a model system. The crosslink density (v_c) is varied between values comparable with (v_c = 9 × 10²⁵ chains m⁻³), up to values much higher than (v_c = 235 × 10²⁵ chains m⁻³), the entanglement density in the thermoplastic PS-PPE system. The maximum macroscopic toughness proportional to the strain to break (λ_macr) or given by the slow-speed fracture toughness (G_Ic) and the notched high-speed tensile toughness (G_h) of core-shell rubber-modified epoxides uniquely increases with an increasing molecular weight between crosslinks (M_c). Only by using extreme testing conditions (notched high-speed impact testing), could the ID_c of a limited range of epoxides be determined: 0.21 μm (v_c = 9 × 10²⁵ chains m⁻³) ≤ ID_c ≤ 0.29 μm (v_c = 14 × 10²⁵ chains m⁻³). Both the experimentally determined values of ID_c and the toughness of the epoxides compare well with the values determined for the entangled thermoplastic PS-PPE model system in the same range of network densities, elucidating the principal similarity of the influence of entanglements and crosslinks on the deformation processes. Good agreement was observed between the experimentally determined values of ID_c of the epoxides and the values predicted by the simple model introduced in part 2 of this series.