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71.
Reactive distillations for the production of ethyl acetate (EtAc) and isopropyl acetate (IPAc) are classified as the type-II process where the first column consists of a reactive zone and a rectifying section followed by a stripper [Tang et al., 2005. Design of reactive distillations for acetic acid esterification with different alcohols. A.I.Ch.E. Journal 51, 1683-1699]. Instead of using pure alcohols and acetic acid as reactants, this paper studies the effects of reactant purity on the design and control of reactive distillation. This offers significant economical incentives (by reducing raw materials costs), because ethanol forms an azeotrope with water at 90 mol% and isopropanol/water has an azeotrope at 68%. The purities of the acid is set to 95% for acetic acid (industrial grade), 87% for ethanol, and 65% for isopropanol. The results show that the total annual costs (TAC) increase by a factor of 5% for EtAc and 8% for IPAc production using reactive distillation. Next, the operability of the reactive distillations with azeotrope feeds is explored. Three disturbances, feed flow, acid feed purity, and alcohol feed composition, are introduced to assess control performance using dual-temperature control and one-temperature-one-composition control. Simulation results indicate good control performance can be achieved for reactive distillation with azeotropic feeds. 相似文献
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提出了用精馏塔对含氮天然气脱除N2生产液化天然气(LNG),精馏塔塔釜液位的一种控制方法。该方法以脱氮分离效率和稳定的产品(LNG)出料温度为控制目标,建立了塔釜液位控制模型并仿真。整个闭环控制模型包括被控对象传递函数,调节阀传递函数,PID控制传递函数和检测传递函数。其中调节阀传递函数的建立,采用先计算阀位-Cv值(流量系数)曲线;然后通过系统辨识法[1]求得数学模型;最后利用泰勒级数把非线性化转化为线性化并求得传递函数。通过Matlab软件[2]的仿真,在阶跃干扰下,得到了合适的液位变化曲线和合适的阀位变化[3]。 相似文献
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A simple method has been developed to optimally design a distillation sequence with a fixed degree of flexibility in feed composition and flowrate, and accounts for uncertainty in stage efficiency, K-value and beat transfer coefficient calculations. The method minimizes a weighted cost function and ensures both optimal and feasible operation in the range of flexibility/uncertainty by using an approach termed “practical feasibility”. The method was tested on a 4 column distillation sequence separating a 5 component light alkane feed mixture. Results are presented to illustrate the effect of uncertainty on sequence cost and column overdesign. 相似文献
77.
伴有平衡反应的分离过程的数学模拟——(Ⅱ)催化精馏塔的模拟计算 总被引:1,自引:0,他引:1
提出了平衡反应的非均相催化反应精馏过程的微分数学模型。应用多目标打靶法和 Newtor-Raphson 迭代对模型方程进行了求解。本算法应用于非理想系统,反应动力学未知的快速可逆反应过程。可求得沿塔最大转化率和平衡浓度分布。应用本算法对 MTBE 的催化反应过程进行了模拟计算,能快速稳定收敛。计算结果与文献数据进行比较,表现出良好的一致性。 相似文献
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A methodology to improve the efficiency of stochastic methods applied to the optimization of chemical processes with a large number of equality constraints is presented. The methodology is based on two steps: (a) the optimization of the simulation step, which involves the optimum choice of design variables and subsystems to be simultaneously solved; (b) the optimization of the nonlinear programming (NLP) problem using stochastic methods. For the first step a flexible tool (SIMOP) is used, whereby different numerical procedures can be easily obtained, taking into account the problem formulation and specific characteristics, the need for specific initialization schemes and the efficient solution of systems of nonlinear equations. This methodology was applied to the optimization of a reactive distillation process for the production of ethylene glycol. Due to the complexity of the mathematical model, several different numerical procedures were generated, and their influence on the computational burden and on the reliability and accuracy of the optimization to reach the global optimum were studied. The results obtained suggest that in addition to the choice of design variables, the structure of subsystems associated to numerical procedures has a considerable impact on the performance of the optimizers. 相似文献