共查询到19条相似文献,搜索用时 109 毫秒
1.
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。 相似文献
2.
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。 相似文献
3.
4.
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。 相似文献
5.
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 相似文献
6.
7.
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%。 相似文献
8.
《化工进展》2017,(3)
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。 相似文献
9.
《现代化工》2016,(7)
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。 相似文献
10.
11.
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 相似文献
12.
13.
《Journal of aerosol science》2007,38(7):764-774
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. 相似文献
14.
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. 相似文献
15.
Maryam Askarishahi Mohammad‐Sadegh Salehi Stefan Radl 《American Institute of Chemical Engineers》2017,63(7):2569-2587
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 相似文献
16.
17.
Carlo Castellari Romolo Francesconi Stefano Ottani Fabio Comelli Giovanni Pezzin 《Polymer Engineering and Science》1988,28(2):113-119
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. 相似文献
18.
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。 相似文献
19.
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。 相似文献