恒馏出液组成间歇精馏回流比的控制和调节

计算及模拟间歇精馏过程已成为国内外许多学者的研究课题.以恒馏出液组成操作方式的间歇精馏,调节与控制回流比十分重要,过程计算复杂,计算量也很大.在Excel中,递推公式结合VBA编程求取了初始回流比Ro和最终回流比Re;VBA程序与Excel图表的数据通讯获得了各塔板气液组成的动态数据;Excel与VBA的混合编程得到了蒸馏时间与塔釜组成、塔釜组成与回流比的动态函数关系;为间歇精馏的动态调节、控制回流比和计算机模拟等问题提供了解决的途径.     

回流比恒定的间歇精馏工艺计算方法改进

以正庚烷-正辛烷体系为例,根据R=f(n,XD)=nRmin,以假定最初的馏出液组成XD,0和n值,交替进行两次迭代试差,最终确定最小回流比和适宜回流比,修正了文献所给出的不妥之处。另外,用解析计算取代面积积分,求解釜液量。     

恒回流比多组分间歇精馏计算

采用"瞬间稳态"法计算恒回流比多组分间歇精馏过程.提出操作初始态馏出液组成的设定依据,减少回流比和理论板数设计的盲目性.程序完善多组分间歇精馏回流比和理论板数的计算方法,简化馏出液瞬间组成、平均组成及釜残液瞬间组成的计算过程.     

进料温度和回流比对多元精馏塔能耗的影响——计算机设计与模拟

在 Burroughs—6935大型电子计算机上,对苯—甲苯—乙苯—苯乙烯四元混合物的常压精馏,进行了精馏塔的设计与操作模拟,并在进料温度 T_F=340K～398K(包括冷液,沸点,汽液混合和饱和蒸汽四种进料热状态),回流比 R=1.5～3.5的变化范围内,考察了进料温度和回流比对多元精馏塔再沸釜能耗 q_r 和总能耗 Q_R 的影响。计算结果指出,若保持 R 恒定,进料热状态 Q>1时,与△T_F=10℃相对应的△q_r 随料温的变化幅度约为2×10_3～5×10_3KJ/kg-mol(料液)·hr;Q<1时,约为8×10~3～4×10~4KJ/Kg-mol(料液)·hr。若保持 T_F 恒定,则 R 的增加将使 q_r 也随之增加,同时分离质量也得到提高。精馏塔总能耗 Q_R 随 T_F 和 R 增加而增加。对 Q>1的进料热状态,计算机回归得到:q_r=1.996×10~7×T_F~(-9.464×10~(-5))×R~0.668[KJ/Kg-mol(料液)·hr]     

EXCEL实现恒回流比间歇精馏的计算机仿真

对于恒回流比操作方式的间歇精馏,过程计算量大且公式应用相对复杂,用计算机完成间歇精馏的过程计算及操作仿真已经成为许多国内外学者的研究课题。为了满足系统的响应速度,提高动态釜液量误差,用Excel的VBA、函数、图表及重算等功能,实现间歇精馏的计算机仿真的新方法。在Excel中,建立了间歇精馏过程的数学模型与“数据处理表”,完成多项式拟合,由递推公式确定塔内各塔板液相组成xn与时间t的动态响应关系。获得的六次拟合曲线接近于实测的平衡数据,其相关系数达到0．999,各塔板液相组成xn与时间t的动态响应关系与实际计算吻合较好,获得了较满意的结果,为设计提供有效依据。     

间歇精馏常规设计和优化设计的模型及算法

建立了板式间歇精馏塔在恒馏出液组成操作状况下常规设计及优化设计的数学模型。常规设计模型用数值方法编程求解，对二元理想及非理想溶液均适用。优化设计模型以间歇精馏系统年效益最大为优化目标，用菲波那契法求解单变量优化问题，用复合形法求解多变量优化问题。模型同时考虑对整个间歇精馏系统(包括塔主体、塔顶冷凝器及塔底再沸器)进行优化，更符合工程实际情况。求解模型可得到间歇精馏过程最优的一系列设计和操作参数(如理论板数，塔径，操作回流比，塔釜蒸发量，釜残液组成，冷凝器传热面积及冷却水出口温度，再沸器传热面积及加热蒸汽温度等)。算例表明，对恒馏出液组成间歇精馏单变量及多变量优化设计比常规设计分别提高年效益2．6％和18．9％。     

有机锡配合物{[n-Bu_2Sn(O_2CC_5H_3NCl)]_2O}_2的合成、结构及量子化学研究

二正丁基氧化锡和2-氯-3-吡啶甲酸反应,合成2-氯-3-吡啶甲酸二正丁基锡配合物{[n-Bu2Sn(O2CC5H3NCl]2O}2.经X-射线衍射法测定了晶体结构.晶体属三斜晶系,空间群P-1,晶体学参数a=1.17841(9)nm,b=1.20811(9)nm,c=2.7460(2)nm,α=80.5330(10)°,β=84.1140(10)°,γ=64.2450(10)°,Z=2,V=3.4709(5)nm3,Dc=1.521 mg·m-3,μ(MoKa)=1 628 mm-1,F(000)=1592,R1=0.0430,wR2=0.1005.化合物是以Sn2O2构成的平面四元环为中心环的二聚体结构,锡原子均为五配位的畸变三角双锥形.用量子化学从头计算其结构,探讨配合物的稳定性、分子轨道能量以及一些前沿分子轨道的组成特征.     

萃取精馏法分离正丁醇-异丁醇的模拟和实验研究（英文）

采用连续侧线出料精馏法对原料进行预处理,切取正丁醇-异丁醇富集液。采用色谱法在汽液平衡釜上探索正丁醇-异丁醇在溶剂中的分配效果,选择甘油为最适合的萃取溶剂。运用Aspen Plus模拟软件对正丁醇-异丁醇萃取精馏塔进行过程模拟,考察了蒸馏流率、理论塔板数、原料和溶剂的进料位置、回流比、溶剂比对正丁醇异-丁醇混合物分离效果的影响。通过正交化设计优化和验证实验,得到最佳萃取精馏塔的操作条件,即蒸馏流率D9=17 kg/br,理论塔板数N=49,原料进料位置NF--29,溶剂进料位置NS=8,回流比R=6,溶剂比S:F=11:1。研究结果表明在最佳操作条件下,塔顶异丁醇纯度可以提高到99.80%,得率为89.38%,塔底正丁醇纯度可达到97.53%,得率为99.96%,验证实验结果与模拟结果相对误差小于1%。研究结果为进一步实验研究提供基础参数。     

精馏塔的节能控制——再沸器液位自调

问题的提出流程:每个精馏塔设两个再沸器(即列管式加热器),其作用是用蒸汽加热塔釜液以进行循环精馏,外来蒸汽减压后进到再沸器,与塔釜液通过列管进行顺流热交换,蒸汽从再沸器出来再去原料预热器加热粗甲醇,最后以冷凝液的形式送到冷凝水槽。原热能利用:蒸汽减压到3kg/cm~2(atu),其饱和蒸汽温度 tH=142.92℃将釜液加热到106℃±,再沸器排出蒸汽温度还有105～115℃。粗甲醇预热器来料温度一般72℃±,预热后的温度要求82～84℃。再沸器液位投运以前蒸汽耗量为2.0～2.3吨/时。表现出热量有余,常常打开支路使蒸汽白白     

VBA实现恒馏出液组成间歇精馏的计算机模拟

对于恒馏出液组成操作方式的间歇精馏,过程计算相对复杂,计算量很大。在常用软件Excel中利用VBA实现塔内各塔板液相组成xn与时间t的动态响应,完成间歇精馏的过程计算及模拟,具有可视化、即时化、自动化等优点,可行且有实用意义。     

一个常微分方程的整体解存在性

该文研究了常微分方程(d2u/dx2)+K(x)2n=0在(-1,1)上整体解的存在性,此问题源于H2上的预定保角高斯曲率问题,证明了一个存在定理,解释了其几何意义.     

洋葱伯克霍尔德菌CF-66发酵动力学研究

研究在3.7 L发酵罐内分批培养洋葱伯克霍尔德菌CF-66过程中生物量、柠檬酸钠和产物CF66I含量的变化规律.利用MATLAB软件将实验数据非线性拟合,确定模型参数,建立洋葱伯克霍尔德菌CF-66分批发酵动力学模型.菌体生长、底物柠檬酸钠消耗以及产物CF661生长动力学模型分别为dx/dt=0.3220(1-x/4.2504)x、ds/dt=-(1/0.0278)dx/dt和dp/dt=0.1244x.将模型预测值与实验值比较,表明模型非常实用.     

Alcuni problemi relativi alle formule di quadratura del tipo di tchebycheff

In this paper we study quadrature formulas of the form $$\int\limits_{ - 1}^1 {(1 - x)^a (1 + x)^\beta f(x)dx = \sum\limits_{i = 0}^{r - 1} {[A_i f^{(i)} ( - 1) + B_i f^{(i)} (1)] + K_n (\alpha ,\beta ;r)\sum\limits_{i = 1}^n {f(x_{n,i} ),} } } $$ (α>?1, β>?1), with realA _i ,B _i ,K _n and real nodesx _n,i in (?1,1), valid for prolynomials of degree ≤2n+2r?1. In the first part we prove that there is validity for polynomials exactly of degree2n+2r?1 if and only if α=β=?1/2 andr=0 orr=1. In the second part we consider the problem of the existence of the formula $$\int\limits_{ - 1}^1 {(1 - x^2 )^{\lambda - {1 \mathord{\left/ {\vphantom {1 2}} \right. \kern-\nulldelimiterspace} 2}} f(x)dx = A_n f( - 1) + B_n f(1) + C\sum\limits_{i = 1}^n {f(x_{n,i} )} }$$ for polynomials of degree ≤n+2. Some numerical results are given when λ=1/2.     

Sulle formule di quadratura di Tschebyscheff

For the Tschebyscheff quadrature formula: $$\int\limits_{ - 1}^1 {\left( {1 - x^2 } \right)^{\lambda - 1/2} f(x) dx} = K_n \sum\limits_{k = 1}^n {f(x_{n,k} )} + R_n (f), \lambda > 0$$ it is shown that the degre,N, of exactness is bounded by: $$N \leqslant C(\lambda )n^{1/(2\lambda + 1)} $$ whereC(λ) is a convenient function of λ. For λ=1 the complete solution of Tschebyscheff's problem is given.     

Directional morphological filtering

We show that a translation invariant implementation of min/max filters along a line segment of slope in the form of an irreducible fraction dy/dx can be achieved at the cost of 2+k min/max comparisons per image pixel, where k=max(|dx|,|dy|). Therefore, for a given slope, the computation time is constant and independent of the length of the line segment. We then present the notion of periodic moving histogram algorithm. This allows for a similar performance to be achieved in the more general case of rank filters and rank-based morphological filters. Applications to the filtering of thin nets and computation of both granulometries and orientation fields are detailed. Finally, two extensions are developed. The first deals with the decomposition of discrete disks and arbitrarily oriented discrete rectangles, while the second concerns min/max filters along gray tone periodic line segments     

Un metodo del terzo ordine per l'integrazione numerica dell'equazione differenziale ordinaria

For the numerical integration of the ordinary differential equation $$\frac{{dy}}{{dx}} = F(x,y) y(x_0 ) = y_0 \begin{array}{*{20}c} x \\ {x_0 } \\ \end{array} \varepsilon [a,b]$$ a third method utilizing only two points for every step, is determined different from the analogous Runge-Kutta method employing three points; it is useless take the first step as the «pseudo Runge-Kutta method». The truncation error is given, the convergence is proved and finally a numerical exercise is given.     

Sul grado di precisione di formule di quadratura del tipo di tchebycheff

In this paper we study quadrature formulas of the types (1) $$\int\limits_{ - 1}^1 {(1 - x^2 )^{\lambda - 1/2} f(x)dx = C_n^{ (\lambda )} \sum\limits_{i = 1}^n f (x_{n,i} ) + R_n \left[ f \right]} ,$$ (2) $$\int\limits_{ - 1}^1 {(1 - x^2 )^{\lambda - 1/2} f(x)dx = A_n^{ (\lambda )} \left[ {f\left( { - 1} \right) + f\left( 1 \right)} \right] + K_n^{ (\lambda )} \sum\limits_{i = 1}^n f (\bar x_{n,i} ) + \bar R_n \left[ f \right]} ,$$ with 0<λ<1, and we obtain inequalities for the degreeN of their polynomial exactness. By using such inequalities, the non-existence of (1), with λ=1/2,N=n+1 ifn is even andN=n ifn is odd, is directly proved forn=8 andn≥10. For the same value λ=1/2 andN=n+3 ifn is evenN=n+2 ifn is odd, the formula (2) does not exist forn≥12. Some intermediary results regarding the first zero and the corresponding Christoffel number of ultraspherical polynomialP _n ^(λ) (x) are also obtained.     

The effects of frequently rotating shiftwork on sleep and the family life of hospital nurses

The effects of three frequently rotating shifts in an irregular sequence on the daily activities of 239 Japanese female hospital nurses were studied by the time-budget method. The nurses recorded their daily activities for several consecutive days. The questionnaire was returned by 80·8% of the participants, and recordings of 1016 days were analysed. A two-way analysis of variance clarified that the shift combination influenced the daily activities. The most distinct result was that nurses spent significantly more time on free-time activities on the day when they worked the night shift followed by the evening shift than they did on the day when they worked any other shift combination. Nurses offset sleep deprivation either by sleeping during the day before and after working the night shift (82–100%) or by sleeping 2 to 4?h later in the morning after working the evening shift and on days off. There was a strong positive correlation between total sleep time (including day sleep) and the length of the interval between two consecutive shifts (r = 0·95, p < 0·001). This result suggests that more than 16 h between work shifts is required to allow more than 7?h of total sleep time. In an analysis by household status, nurses who had young children (average age, 2·8 years) slept less and spent less time on free-time activities than did other nurses.     

An enhanced integrated aerodynamic load/dynamic optimization procedure for helicopter rotor blades

An enhanced integrated aerodynamic load/dynamic optimization procedure is developed for minimizing vibratory root shears and moments of a helicopter rotor blade. The optimization problem is formulated with 4/rev inplane shears at the blade root as objective functions. Constraints are imposed on 3/rev radial shear, 3/rev flapping and torsional moments, 4/rev lagging moment, blade natural frequencies, weight, autorotational inertia, centrifugal stress and rotor thrust. The global criteria approach is used for formulating the multiobjective optimization. Design variables include spanwise distributions of blade bending stiffnesses, torsional stiffness, nonstructural mass, chord, radius of gyration and blade taper ratio. The programme CAMRAD is coupled with an optimizer, which consists of the programme CONMIN and an approximate analysis. The optimization procedure is applied to an advanced rotor as a reference design. Optimum blade designs, obtained with and without a constraint on the rotor thrust, are presented and are compared to the reference blade. Substantial reductions are obtained in the vibratory root forces and moments. As a byproduct, improvements are also found in some performance parameters which were not considered during the formulation of the optimization problem. The effect of thrust constraint on the values of the vibratory forces and moments is demonstrated by varying the magnitude of the prescribed thrust. A proper choice of the move limit parameter, used in the approximate analysis, is shown to have significant effect on the optimum results.Notation AI autorotational inertia, lb-ft² - c chord, ft - c _r root chord, ft - c _t tip chord, ft - C _P power coefficient - C _T thrust coefficient - C _X propulsive force coefficient - EI _xx ,EI _zz bending stiffnesses, lb-ft² - bending stiffnesses at blade root, lb-ft² - f ₃,f ₄,f ₅,f ₆ natural frequencies of first four coupled elastic modes, per rev - f _r 3/rev radial shear, lb - f _x 3/rev inplane shear, lb - f _z 4/rev vertical shear, lb - F, objective functions - approximate objective function - F _x inplane component of blade airload, lb/ft - F _z normal component of blade airload, lb/ft - gj j-th constraint function - approximate constraint function - GJ torsional stiffness, lb-ft² - GJ _r torsional stiffness at blade root, lb-ft² - k _r principle radius of gyration at blade root, ft - (L/D)_max maximum lift to drag ratio of an airfoil - m _c 3/rev torsional moment, lb-ft - m _x 3/rev flapping moment, lb-ft - m _z 4/rev lagging moment, lb-ft - ML move limit - n integer, 0 n 1 - N number of blade nodes - NCON number of constraints - NDV number of design variables - NSEG number of blade segments - R blade radius, ft - s _i centrifugal stress ini-th segment, lb/ft² - s _max maximum allowable stress, lb/ft² - T thrust, lb - T _ref thrust of reference rotor, lb - w _j nonstructural weight per unit length atj-th node, lb/ft - W total blade weight, lb - x, y, z reference axes - angle of attack, degree - taper ratio - _i i-th design variable - advance ratio - thrust-weighted solidity - blade azimuth angle, degree - rotor angular velocity, rad/sec