煤气化废水处理中双侧线汽提塔的应用

针对具有较高pH值的煤气化废水,采用酸性气饱和煤气化废水能降低废水pH值,改善萃取条件后进行萃取。但萃取后的萃余液中存在大量的酸性气、氨和萃取剂。为了回收氨和萃取剂,并脱除酸性气,在原有工作基础上,采用双侧线汽提塔处理萃余液,该塔塔顶分离酸性气,上侧线回收萃取剂,下侧线回收氨。文中是这一建议流程的后续研究工作。通过流程模拟,对影响双侧线汽提塔分离效果的因素,如热进料位置和塔顶采出量、冷热进料比和冷进料温度、上侧线采出位置和采出量、下侧线采出位置和采出量等进行模拟优化。模拟结果显示:双侧线汽提塔可满足塔釜水净化的要求,且有效地分离酸性气、氨和萃取剂,最大程度地回收氨和萃取剂,初步证明了双侧线汽提塔工艺的可行性。     

炼油减压精馏塔汽提工艺传质过程模拟与分析

为了揭示减压塔汽提工艺的传质过程特性,进而改进汽提操作,采用改进的减压精馏过程模拟方法和传质计算方法,分析了炼油常减压装置的汽提工艺的传质特点。在深化对于汽提工艺的理解基础上论证了采用填料汽提塔(段)的必要性以及设计、分析的基本方法。计算分析结果表明侧线汽提塔内填料分离性能保持恒定,汽提塔的分离效率与减压塔对应分离段接近,所以在设计和操作中应给予汽提塔(段)充分重视。减压塔底汽提段的工艺和水力学特点与侧线汽提塔相同。塔底汽提蒸汽质量流率应小于减压塔进料质量流率1%,否则将导致减压塔整体分离效率降低。     

基于随机优化的热耦合复杂精馏系统的综合(Ⅰ)模型化方法

基于随机型最优化策略,针对包含简单塔、带有侧线蒸出及侧线汽提塔的复杂塔、全热耦合（或Petlyuk）塔的热耦合复杂精馏塔系统的综合问题,提出一种模型化方法.针对热耦合复杂精馏流程系统所需塔段数目以及冷凝器和再沸器数目的不确定性,提出了一种分解求解策略,将原问题分解成一系列具有不同塔段数的子问题分别求解;针对流程结构的优化提出一种流程结构的编码表达法,该方法将问题的分离序列结构和热耦合方式分别用两组编码表示,对分离序列的编码采用了数据结构理论中的二叉树排序方法,使流程结构的描述变得更加简便;最后以预分馏塔组分回收率及回流比为连续变量,建立了热耦合复杂精馏系统优化的[JP+1]混合整数非线性规划（MINLP）模型,该模型用改进的模拟退火算法求解,可同时得到优化的流程结构和操作参数.     

酸性水汽提塔的模拟计算及优化

运用Aspen Plus流程模拟软件,对单塔加压、侧线抽出工艺的酸性水汽提塔进行模拟,通过热进料位置、冷进料比例、侧线抽出位置及侧线抽出量的分析,确定汽提塔操作参数,对汽提塔设计提供指导。     

液-液萃取过程的模拟计算

本文研究了流量加和法(SR法),Bennett改进的牛顿-拉夫森法(BNR法)以及将两者结合的SR-BNR法在多级逆流液-液萃取过程模拟计算中的应用,并根据对十个例子所作的平行计算结果,分析了各法的优缺点。 按通用塔模型编制的萃取计算程序《EXTR》可应用于常规萃取和具有多股进料、溶剂、侧线以及采用回流的复杂萃取过程计算。 本计算中使用的活度系数方程包括NRTL,UNIQUAC和Margules方程。     

煤气化废水处理中双侧线汽提塔的加碱脱氨

煤气化废水中不仅存在CO32-、HCO3-、HS-等阴离子,还存在Cl-、SO42-等阴离子,因此废水中既存在游离铵盐也存在固定铵盐.仅采用煤气化废水处理中的双侧线汽提技术无法除去固定氨,导致处理后废水的氨的质量浓度严重超标,影响后续生化处理.为了降低废水中固定氨的质量浓度,在双侧线汽提塔内采用加碱脱氨技术,并借助流程模拟,对加碱位置和加碱量进行优化.结果表明,在塔釜总氨及总酸的质量浓度满足出水要求的前提下,加碱后双侧线汽提塔固定氨的脱除率达99.8％.改善废水水质的同时回收了大量氨,具有较好的社会和经济效益.     

乙醇-苯-水非均相共沸精馏过程稳态模拟与动态控制

利用Aspen Plus流程模拟软件,以苯为轻夹带剂,建立了乙醇-苯-水三元非均相体系两塔共沸精馏工艺流程。对工艺流程中关键设备汽提塔和脱水塔进行了稳态模拟与优化,优化后的结果为:汽提塔共31块塔板,塔直径2.07 m,塔顶压力0.203 MPa,塔顶回流罐的温度313 K,回流比0.648,再沸器的热负荷9.149 MW;脱水塔共21块塔板,塔直径1.38 m,塔顶压力0.101 MPa,塔顶回流罐的温度347 K,回流比0.2,再沸器的热负荷4.57 MW。最终在汽提塔塔底可得到摩尔分数99.6%的乙醇产品。采用Aspen Dynamic建立了全工艺流程的控制结构,并对进料流量和进料组成的扰动进行了动态分析,结果表明:动态控制结构可满足对产品纯度的设计规定要求。研究结果对工艺与控制方案的选择具有重要的现实指导意义。     

含硫污水汽提塔的模拟与优化

利用流程模拟计算软件 PROII 对含硫污水汽提塔进行模拟计算,得出汽提塔温度分布,获得了适宜的热冷进料配比、侧线采出位置及热进料温度,确定和优化了该塔的最佳操作条件.     

基于改进优序数法的脱硫塔综合受力危险区域确定方法研究

在烧结工艺过程中，应力变化会对脱硫塔强度和结构稳定性产生影响，确定结构危险区域对于保障结构安全非常重要。对传统的优序数法进行改进，采用客观赋权法中的CRITIC算法构建新的数学模型，对筒体结构中的轴向、环向、剪切应力指标进行计算后排序；以某工程中的脱硫塔为例，运用改进的优序数法计算优序数值并排序，得出危险区域分别为进风口、出风口以及脱硫塔变径处；利用ANSYS软件对脱硫塔模型应力分布进行数值模拟计算，将模拟结果与上述算法计算结果进行对比，验证了改进优序数法的准确性与可行性。改进的优序数法综合考虑了各项指标间的相关性，降低了传统方法的主观性，可以用于指导脱硫塔结构危险区域的确定。     

酸性水汽提装置长周期运行的问题及措施

详细分析了炼油企业酸性水汽提装置在长周期运行过程中出现问题的主要原因及处理措施,并提出了相应的改进措施.汽提装置的汽提塔下部塔盘、酸性水/净化水换热器及重沸器严重结垢,导致汽提塔塔盘温度、热进料温度和净化水出口温度异常波动、凝结水收集罐液位波动等问题,停车检修后分析结垢物的位置和性状,采取冲洗清理措施并对汽提塔重沸器操...     

Experimental studies of air-blast atomization on the CO2 capture with aqueous alkali solutions

In this work, an air-blast atomizing column was used to study the CO₂ capture performance with aqueous MEA (mono-ethanol-amine) and NaOH solutions. The effects of gas flow rate, the liquid to gas ratio (L/G), the CO₂ concentration on the CO₂ removal efficiency (η) and the volumetric overall mass transfer coefficient (K_Ga_v) were investigated. The air-blast atomizing column was also compared with the pressure spray tower on the studies of the CO₂ capture performance. For the aqueous MEA and NaOH solutions, the experimental results show that the η decreases with increasing gas flow rate and CO₂ concentration while it increases with increasing L/G. The effects on K_Ga_v are more complicated than those for η. When the CO₂ concentration is low (3 vol%), K_Ga_v increases with increasing gas flow rate while decreases with increasing L/G. However, when the CO₂ concentration is high (9.5 vol%), as the gas flow rate and L/G increases, K_Ga_v increases first and then decreases. The aqueous MEA solution achieves higher η and K_Ga_v than the aqueous NaOH solution. The air-blast atomizing column shows a good performance on CO₂ capture.     

Simulation of Multi-component Multi-stage Separation Process--An Improved Algorithm and Application

This paper presents a flexible model and a robust algorithm for simulation of multi-stage multi-component separation processes in which multiple feeds, side streams, strippers and/or side heat exchangers are involved. The improved algorithm effectively accelerates the speed of convergence and offers better stability by introducing a damping factor for updating the stripping factor, and also reduces the requirement on the initial estimates by updating the Joacobian matrix directly with the stripping factor and enthalpy. On the other hand, an efficient algorithm was proposed to solve the approximate tri-diagonal matrix (containing the off-band elements) derived from the material balance equations (M equations) and phase equilibrium equations (E equations), the advantages and simplicity of the "inside-out" technique of the Russell are retained. The present algorithm was demonstrated to be effective in simulating complex separation columns with typical case studies.     

Experimental study of the mass transfer behavior of carbon dioxide absorption into ternary phase change solution in a packed tower

Phase change absorbents for CO₂ are of great interest because they are expected to greatly reduce the heat energy consumption during the regeneration process. Compared with other phase change absorbents, monoethanolamine (MEA)-sulfolane-water is inexpensive and has a fast absorption rate. It is one of the most promising solvents for large-scale industrial applications. Therefore, this study investigates the mass transfer performance of this phase change system in the process of CO₂ absorption in a packed tower. By comparing the phase change absorbent and the ordinary absorbent, it is concluded that the use of MEA/sulfolane phase change absorbent has significantly improved mass transfer efficiency compared to a single MEA absorbent at the same concentration. In the 4 mol·L^-1 MEA/5 mol·L^-1 sulfolane system, the CO₂ loading of the upper liquid phase after phase separation is almost zero, while the volume of the lower liquid phase sent to the desorption operation is about half of the total volume of the absorbent, which greatly reduces the energy consumption. This study also investigates the influence of operating parameters such as lean CO₂ loading, gas and liquid flow rates, CO₂ partial pressure, and temperature on the volumetric mass transfer coefficient (K_Ga_V). The research shows that K_Ga_V increases with increasing liquid flow rate and decreases with the increase of lean CO₂ loading and CO₂ partial pressure, while the inert gas flow rate and temperature have little effect on K_Ga_V. In addition, based on the principle of phase change absorption, a predictive equation for the K_Ga_V of MEA-sulfolane in the packed tower was established. The K_Ga_V obtained from the experiment is consistent with the model prediction, and the absolute average deviation (AAD) is 7.8%.     

Performance of CO2 absorption in a diameter-varying spray tower

The application of spray towers for CO₂ capture is a development trend in recent years. However, most of the previous jobs were conducted in a cylindrical tower by using a single spray nozzle, whose configuration and performance is not good enough for industrial application. To solve this problem, the present work proposed a diameter-varying spray tower and a new spray mode of dual-nozzle opposed impinging spray to enhance the heat and mass transfer of CO₂ absorption process. Experiments were performed to investigate the mass transfer performance (in terms of the CO₂ removal rate (η) and the overall mass transfer coefficient (K_Ga_e2 are major factors, which affect the absorption performance and the maximums of η and K_Ga_e that are 94.0% and 0.574 kmol·m^-3·h^-1·kPa^-1, respectively, under the experimental conditions. Furthermore, new correlations to predict the mass transfer coefficient of the proposed spray tower are developed in various CO₂ concentrations with a Pearson Correlation Coefficient over 90%.     

Naphtali-Sandholm distillation calculations for NGL mixtures near the critical region

Multicomponent distillation calcultions are carried out using a modification of the Naphtali-Sandholm column calcultaion procedure coupled with the Soave-Redlich-Kwong equation of state for generating K-values and enthalpies.

The modified Naphtali-Sandholm procedure is applicable when the individual stage efficiencies are unity and the K-values are not strongly dependent on the vapour-phase composition. For a column with M components and N stages, N(M + 2) relationships are set up.

The N(M + 2) equations are solved using Newton-Raphson iteration with imposed maximum allowable changes of the independent variables between iterations. Analytical derivatives of the K-values and enthalpies with respect to composition and temperature are employed in the Jacobian.

The method has been used for the process development and design of distillation columns associated with the separation of natural gas liquids (NGL). Fast and safe convergence is obtained even near the critical region.     

The concave-wall jet characteristics in vertical cylinder separator with inlet baffle component

The concave-wall jet was formed in the vertical cylinder separator with inlet baffle component. The effect of curvature of radial baffle on the jet flow in the separator was investigated by the experiment of concentration and the numerical simulation of species transport. The results show that the concave-wall jet was confined within the narrow region near the concave-wall and the flow disturbance in the center of separator was weakened. The distribution of concentration and the flow region of wall jet depended on the curvature of radial baffle (K). Compared with the turbulent intensity of the plate baffle (K=0), that of concave baffle (K=2) reduced by 6.1% and the turbulent intensity of convex baffle (K=-2) increased by 13.5%. The best flow stability was obtained by the concave baffle because the baffle outlet was similar to convergent nozzle. The outlet convergent angle was between 0° and 19.5° when 0 ≤ K ≤ 2. The secondary vortices were caused by the tangential velocity irregularity on the cross-section of two axial baffles in the separator with convex baffle. The baffle with K ≥ 0 was more suitable in separator inlet than that with K < 0.     

精馏塔MESH方程组求解的一种双重迭代法

讨论了精馏塔MESH方程组的求解方法,介绍了相平衡系数简化模型及构造的双重迭代算法.该法具有数值稳定、占用内存空间较小、快速收敛等特点.     

甲醇制芳烃K-means-PSO-SVR局部建模及优化

针对甲醇制芳烃（MTA）过程数据样本趋同、维度高、非线性、强耦合、局部差异大的特性,提出了一种K-means-PSO-SVR的局部建模方法,用以解决单一全局模型预测精度低,鲁棒性不强的问题。该方法首先用K-means算法对样本空间的数据进行聚类,实现对样本空间k个区域的划分,再用经过粒子群优化算法（PSO）优化过超参数的支持向量回归算法（SVR）在划分好的样本空间上建立相互独立的局部模型,最终将建立的k个相互独立的局部模型组合起来组成覆盖整个样本空间的集成模型。在不同噪声水平下将K-means-PSO-SVR方法的建模效果与单一全局SVR、BP神经网络和线性回归3种算法的建模效果进行了比较分析,结果表明：K-means-PSO-SVR局部建模方法的性能在所有水平的噪声下都明显优于其他3种建模方法,并且该方法对噪声具有很强的鲁棒性。以建立的数据模型为基础优化了两段式固定床甲醇制芳烃的关键工艺参数,并用5次独立重复实验验证了优化结果的可靠性,得出当一段温度为446.2℃、二段温度为467.3℃、甲醇体积空速为0.4h^-1、压力为0.64MPa时反应产物中苯、甲苯和二甲苯（BTX）的总收率最高,最高收率为44.30%。     

Performance evaluation of hybrid constructed wetlands for the treatment of municipal wastewater in developing countries

In developing countries, high cost of conventional wastewater treatment is a major hindrance in its application. Constructed wetlands (CWs) offer low-cost and effective solution to this issue. The current study aimed to evaluate an innovative maneuver of CWs i.e. hybrid flow constructed wetlands (HCWs) for municipal wastewater (MWW). The HCWs included two lab scale CWs; one horizontal and one vertical, in series. Local plant species were used. HCWs were operated in both, batch and continuous mode. Batch mode was used to (1) optimize detention time and (2) find pollutants removal efficiency. Continuous operation (at batch optimized retention time) was carried out for the evaluation of mass removal rate, r (g·m^-2·d^-1), volumetric rate constant, K_v (per day) and areal rate constant, K_a (m·d^-1). Among two local plants tested, Pistia stratiotes gave better removal efficiency than Typha. Optimum detention time in HCWs was found to be 8 days (4 + 4 each). The optimum COD, BOD, TSS, TKN and P removal observed for Pistia stratiotes planted HCWs was 80%, 84%, 82%, 71% and 88% respectively. Effluent standards for COD, BOD and TSS were met at optimum conditions. The values of K_a and K_v demonstrated that more removal occurred in vertical flow as compared to horizontal flow CW.     

流动聚焦微通道内牛顿微液滴在幂律剪切致稀流体中的生成研究

采用开源CFD软件OpenFOAM中的interFoam求解器对流动聚焦微通道内微液滴的形成过程进行了数值模拟。通过与文献中的实验数据进行对比,验证了VOF模型和幂律非牛顿流体模型的准确性。并以此为基础模拟了幂律剪切致稀流体中牛顿微液滴的形成过程,研究了幂律流体的幂律指数n和稠度系数K对微液滴生成的影响。研究表明,在滴状和挤压状流型中,离散线颈部宽度与周期内剩余时间呈幂律关系;离散线长度在坍塌阶段呈现线性缓慢增长,在夹断阶段呈现近似指数迅速增长的趋势。随着n和K的增大,液滴的尺寸逐渐减小,而生成频率则逐渐增大,且n的变化比K的变化对其产生的影响更明显。