基于神经网络的多效并流蒸发过程的模拟方法

本文提出一种基于神经网络的多效并流蒸发过程的模拟以及优化算法，并以一简单三效并流蒸发过程为例，详细阐述了神经网络模拟算法的具体步骤。该算法具有对初始值要求不高、收敛速度快，全局收敛性好的特点。     

基于Newton-Raphson法的多效顺流蒸发系统的模拟

建立了普通、复杂顺流蒸发系统的数学模型,采用Newton-Raphson法求解,应用面向对象的Pascal语言编制了该算法的计算程序,可对二至七效常规和复杂并流蒸发系统进行模拟计算。以蔗糖溶液为例,对三效并流的5种流程进行了计算和比较,结果表明将各效冷凝液全部用于预热原料的多效蒸发流程能耗最低,蒸发器面积最小。     

海水淡化热泵并流多效蒸发系统设计的模型与解法

为了大幅降低海水淡化过程的能耗,将蒸汽喷射式热泵技术引入海水淡化多效蒸发系统中,并建立带热泵的海水淡化并流多效蒸发系统的模型,用迭代法结合矩阵法求解该模型,结果表明蒸汽喷射式热泵技术具有较明显的节能效果,热泵的喷射系数越大,或热泵的抽汽位置越往后效,节省的生蒸汽消耗量越大,节能效果越好,但同时蒸发器的传热面积也越大,在满足约束条件下存在最佳的热泵喷射系数和最佳的热泵抽汽位置。     

多元电解质溶液多效蒸发系统设计计算

该文开发了多元电解质溶液多效蒸发过程一个比较有用的软件,包括常用电解质物性数据库,传热系数的求取和各过程参数优化。可用于并流、逆流和各种错流蒸发系统。通过新的矩阵变换将各种流型的液相、汽相和固相衡算关系对应起来,构成的方程用线性技术高斯约当消去法重复求解。该算法可广泛应用于任意效数的各种类型蒸发系统。     

复杂逆流多效蒸发系统常规设计的模型与算法

建立了有冷凝水闪蒸和额外蒸汽引出的复杂逆流多效蒸发系统的数学模型 ,常规逆流多效蒸发模型只是该模型的一个特例。提出一种新算法———迭代法结合矩阵法求解模型并给出算法框图。迭代法结合矩阵法与目前较先进的Broyden法相比 ,具有对初值要求不高、收敛稳定性好、收敛速度快等优点 ,是求解多效蒸发问题的一种新的有效方法。算例表明 :模型可用于复杂逆流多效蒸发系统的快速求解 ;对三效逆流蒸发NaOH溶液系统 ,采用冷凝水闪蒸可节省加热生蒸汽 10 %左右 ,节能效果显著 ;逆流多效蒸发采用生蒸汽或引出额外蒸汽预热原料液不仅不会节能 ,反而造成热能损失     

对羟基左旋苯甘氨酸三效热泵蒸发结晶工艺的开发研究

分析了对羟基左旋苯甘氨酸母液浓缩结晶过程存在的问题,介绍了三效热泵蒸发结晶工艺。该工艺采用三效并流流程,利用降膜蒸发器、热泵技术进行低温真空蒸发操作。充分利用了一效蒸发器产生的二次蒸汽,新工艺汽水蒸发比降至0.35t/t,左旋苯甘氨酸产量提高约50%。三效热泵蒸发工艺适用于物料处理量大、沸点升高小、蒸发温度低的物料的浓缩结晶。     

多效蒸发用于浓缩含盐废水的模拟研究

多效蒸发是处理高含盐废水的一种有效方法。本文针对多效蒸发流程模拟计算难收敛的特点,提出一个简便估算生蒸汽用量初值的方法,并用于模拟废水的多效蒸发研究。研究结果表明,采用四效蒸发器的综合经济性能最佳,逆流流程使用的换热器面积最小,比并流节省面积32%。     

1,3-丙二醇发酵液蒸发脱水的工艺模拟

1,3-丙二醇(PDO)发酵液中PDO浓度7%~10%,水含量82%~85%,PDO分离提取各工序中蒸发脱水能耗最大、PDO损失率最大。本文利用Aspen Plus软件对PDO发酵液蒸发脱水过程进行了模拟,研究了操作压力与蒸发脱水终点浓缩液中水含量对蒸发脱水过程中PDO收率的影响,比较了并流、逆流和错流多效蒸发流程进行PDO发酵液脱水的优缺点。研究结果表明,PDO发酵液蒸发脱水过程中PDO损失率随浓缩液中水含量降低和操作压力增大而增大,PDO发酵液在操作压力分别为5k Pa、100k Pa、150k Pa的3种条件下蒸发脱水至浓缩液含水量为30%时,PDO损失分别为4.63%、20.04%和24.78%,PDO发酵液在3种不同操作压力条件下浓缩至浓缩液含水量为12.5%时,PDO损失分别增大到23.68%、76.62%和84.95%;并流蒸发流程PDO收率最高,浓缩液含水量30%,PDO收率97.73%,蒸发1t水消耗0.354t蒸汽。     

硫酸铵溶液三效并流蒸发系统的动态模拟

以江苏某化工厂三效并流蒸发含有一定浓度氨气的硫酸铵溶液为例,采用Aspen Plus软件进行稳态模拟,以稳态模拟结果作为动态模拟的初始条件,建立三效并流蒸发系统的动态模型,利用Aspen Dynamics软件对带有基本控制结构的三效蒸发溶液浓缩系统进行研究,分析进料流量、温度和组成发生变化时系统其他参数的变化规律。结果表明,当进料流量、温度及组成发生变化时,液相出口浓度阶跃性变化。为使液相出口浓度保持恒定,制定了2种控制方案,进料流量串级控制和加热蒸汽流量串级控制,并对其控制效果进行比较。动态分析表明,2种控制方案均能稳定液相出口浓度,但加热蒸汽流量串级控制方案超调量更小、恢复时间更短。动态模拟结果对实际生产操作的多效蒸发溶液浓缩系统的控制提供一定的指导作用。     

惰性气体对分子蒸馏过程的影响

本文采用基于Bohzmann方程的Bhatnagar—Gross—Krook模型方程，建立了计算多组分稀薄气体流动的数学模型和求解方法。应用该模型对一维蒸发和冷凝问题进行了数值模拟，考察了惰性气体存在对该过程的影响，着重讨论了蒸发温度、冷凝温度、惰性气体分压以及蒸发面和冷凝面之间的距离等因素对分离因数的影响。     

Vortex motion‐based particle swarm optimisation for energy consumption of alumina evaporation

The aim of the alumina evaporation process is to improve the concentration of sodium aluminate solution by evaporating the excess water contained in the solution. The evaporation is achieved using heat from steam. Since steam consumption is the major operating costs, in this paper, we investigate an operation optimisation problem for the evaporation process to minimise steam consumption subject to a constraint on the particular quality of the final sodium aluminate solution. This paper proposes a new particle swarm optimisation (PSO) algorithm based on vortex motion to solve this optimisation problem. We demonstrate the effectiveness of the PSO algorithm on benchmark functions. We then apply it to a real industrial evaporation process, where the optimal results show that the steam consumption is considerably reduced. © 2012 Canadian Society for Chemical Engineering     

精制盐水热泵蒸发过程模拟

热泵蒸发制盐工艺的经济性与否,取决的主要因素是能耗,因此如何降低能耗成为改进工艺的主要方向。多效蒸发制盐可以通过改变流程、增加效数、增设预热、各效闪发等操作降低工艺的能耗,热泵蒸发制盐主要可以通过改变蒸发压力来降低能耗。用Aspen Plus模拟研究探索热泵制盐节能措施,模拟中采用质量分数为25%的纯盐溶液,选择常压、正压（132.5 kPa）蒸发,计算对比不同压力下的能耗大小,并同五效蒸发制盐能耗进行对比,继而选出最优工艺,实现经济效益最大化。     

Condensation and evaporation of a nano-sized particle moving in a fluid environment

Condensation and evaporation of a low temperature nano-sized argon particle moving in a gas/vapor environment were analyzed using the molecular dynamics simulation. First evaporation temperature for various heating rates was found and successfully compared with the analytic result. Condensation and evaporation rates observed through simulation depended on particle velocity and thermodynamic properties of the gas, and the radial distribution of particle temperature was found to be a good indicator to characterize the process. Characteristics of condensation and evaporation for four different particle velocities and various environmental conditions were discussed in detail. In low gas density environments all the gas atoms got condensed on the particle, and in high gas density environment condensation/evaporation characteristics became much different depending on particle velocity.     

Numerical and experimental analysis of the single droplet evaporation in a ultrasonic spray pyrolysis device

The present study deals with the numerical analysis of the water droplet evaporation in the carrier gas inside an ultrasonic spray pyrolysis (USP) device. Droplet evaporation is studied through numerical computational fluid dynamics simulation using Ansys Fluent version 16.1 software. The governing equations for mass, momentum, and energy contain source terms for the effects of droplet evaporation. The results are provided as time dependent evaporation rate, temperature and diameter of droplet. Additional experimental evaporation of HAuCl₄ solution droplets with temperatures of 80, 100 and 120°C was performed on a USP device. The obtained dried particles of gold chloride were characterized with TEM and analysed for their size and shapes to determine the effect of evaporation rate on the dried particle morphology. This provides insight into selecting optimal parameters for gold nanoparticle synthesis with HAuCl₄ in USP, for targeted sizes and shapes of the nanoparticles.     

Full‐physics simulations of spray‐particle interaction in a bubbling fluidized bed

Numerical simulations of a gas‐particle‐droplet system were performed using an Euler‐Lagrange approach. Models accounting for (1) the interaction between droplets and particles, (2) evaporation from the droplet spray, as well as (3) evaporation of liquid from the surface of non‐porous particles were considered. The implemented models were verified for a packed bed, as well as other standard flow configurations. The developed models were then applied for the simulation of flow, as well as heat and mass transfer in a fluidized bed with droplet injection. The relative importance of droplet evaporation vs. evaporation from the particle surface was quantified. It was proved that spray evaporation competes with droplet deposition and evaporation from the particle surface. Moreover, we show that adopting a suitable surface coverage model is vital when attempting to make accurate predictions of the particle's liquid content. © 2017 American Institute of Chemical Engineers AIChE J, 63: 2569–2587, 2017     

PROVISION与PHEES集成模拟无机盐生产工艺

以ＰＲＯＶＩＳＩＯＮ和ＰＨＥＥＳ为基础,建立了固液相平衡级计算的通用方法,通过自动判别平衡时的相数及析出固相的种类,可获得固液平衡时各相分率和组成,通过对几种无机盐生产的蒸发、结晶流程的模拟计算证明该方法可适用于目前文献中尚难以处理多离子复分解反应体系,从而满足涉及电解质溶液的化工过程的模拟计算与实际生产的需要     

Latent skin in asymmetric loeb-type hollow fiber membrane

A computer simulation model for the latent skin growth inside a hollow fiber polymeric membrane Is developed. The evaporation step is studied using a solvent evaporation Law and a concentration-dependent diffusion coefficient, both derived from data. The solvent concentration profiles inside the fiber are obtained as a function of the evaporation time for different sets of the parameters governing the internal diffusion and the surface evaporation of the solvent. The computer model enables estimation of the role of the parameters in the growth of the asymmetric latent skin.     

汽油装罐油气扩散排放的实验测定及数值模拟

正确预测储油罐收油作业时罐内油气扩散排放规律对研究油品蒸发损耗及污染控制具有重要意义,因而两个关键参数（油罐排放气液比λ及损耗率η）被重点考虑。基于VOF模型、扩散传质模型和RNG k-ε湍流模型,对汽油喷溅式装油损耗进行数值模拟研究。分析比较了不同装油口高度、不同装油速度、不同油罐初始油气浓度条件下罐内的油气扩散规律,并建立汽油装罐蒸发损耗实验平台验证以上数值模拟,模拟值与实验值吻合良好。研究结果表明：装油口位置越高,汽油损耗率η越大,随装油速度增大,高装油口损耗率η最大约为0.34%,低装油口约为0.025%。增大油罐初始油气浓度,高装油口损耗率η最大约为0.44%,中装油口约为0.21%,低装油口约为0.043%。最后建议固定顶油罐大呼吸API损耗评估计算公式考虑装油速度及油罐初始油气浓度对蒸发损耗的影响,并尽量采用低装油口及清洗油罐装油。     

低温液化气体储存容器的绝热性能评价指标研究

采用液氮为低温储存介质,分别进行了试验和数值模拟。得到了低温绝热容器内部介质在不同充装率下的压力和蒸发率变化规律,建立了压升速率与蒸发率之间的关系。说明了压升速率作为低温液化气体储存容器绝热性能评价指标的可行性。