Nonlinear control of polymerization reactor

In this work, nonlinear model based control was applied to the free radical solution polymerization of styrene in a jacketted batch reactor and its performance was examined to reach the required monomer conversion and molecular weight. Optimal temperature profiles for the properties of polymer quality were evaluated using the Hamiltonian optimization method. Total simulation program having mass and energy balances of the jacketed polymerization reactor was used to calculate the optimal trajectories. For control purposes, several experimental and theoretical dynamic studies have been made to observe the validity of simulation program. Experimental and theoretical nonlinear model based control have been investigated to track the temperature at the optimal trajectory Two types of parametric and nonparametric models were evaluated to achieve the temperature control. For this purpose, reaction curve was obtained to calculate the system dynamic matrix as a nonparametric model. In all control work, heat input to the reactor was chosen as a manipulated variable. Nonlinear auto regressive moving average exogenous (NARMAX) giving a relation between heat input and reactor temperature was chosen to represent the system dynamic and this model was used to describe the related control system as a parametric model. NARMAX model parameters were determined by using Levenberg Marquard algorithm. A pseudo random binary sequence (P.R.B.S.) signal was employed to disturb the system. Total simulation program was used to calculate the system and control parameters. Several types and orders were used to construct the NARMAX models. The efficiency and the performance of the nonlinear model based control with the NARMAX model and dynamic matrix were tested to calculate the best model. Nonlinear model based control system was used to control the reactor temperature at desired temperature trajectory experimentally and theoretically. Theoretical simulation results were compared with experimental control data. It was concluded that the control simulation program represents the behavior of the controlled reactor temperature well. In addition, nonlinear model based control keeps the reactor temperature of optimal trajectory satisfactorily.     

不确定推理在火电厂水汽化学过程故障诊断中的应用

以火电厂水汽化学过程中的凝结水、给水、炉水、饱和蒸汽及过热蒸汽等子系统为研究单元,分析系统中故障原因及故障征兆之间的模糊关系;利用不确定推理方法,构建各子系统的诊断模型块及相互间跳转条件,形成一个适用于整个水汽化学过程的故障诊断模型。运用该模型进行故障识别,能够快速准确地得到诊断结果。     

平流多效蒸发系统的数学模型与求解

为了充分利用能量,采用冷凝水闪蒸、引出额外蒸汽及引出各效完成液预热原料液等节能措施,考虑蒸发过程有固相析出的情况,建立了由多效蒸发和多级预热两个子系统构成的平流多效蒸发系统数学模型。将物料衡算和热量衡算方程组写成矩阵方程的形式,保留或舍弃矩阵方程中的相关块矩阵,模型就能代表有或无固相析出、有或无冷凝水闪蒸、有或无引出各效完成液预热原料液以及不同情况任意组合的平流多效蒸发过程,该模型还可以用于计算不同效数的平流多效蒸发过程,实现模型的通用。利用智能拟合法,将系统的固液相平衡数据拟合成相平衡方程,实现模型的计算机编程求解。用迭代法结合矩阵法求解模型,研究结果表明,平流多效蒸发系统常规设计的数学模型具有通用性,采用冷凝水闪蒸、引出额外蒸汽预热原料液、引出各效完成液预热原料液是有效的节能技术,对四效平流蒸发含NaCl的NaOH溶液系统,采用以上节能措施可节省加热生蒸汽30%左右,节能效果显著。求解模型的算法稳定且高效。     

Parametric and nonparametric model based control of a packed distillation column

Parametric and nonparametric model based control systems were applied to control the overhead temperature of a packed distillation column separating methanol–water mixture. Experimental and theoretical studies have been done to observe the efficiency and performance of both control systems. Generalized predictive control (GPC) system based on a parametric model has been tried to keep the overhead temperature at the desired set point. First, a parametric model which is controlled auto regressive integrated moving average (CARIMA) was developed and then the parameters of this model were identified by applying pseudo random binary sequence (PRBS) and using Bierman algorithm. After that this model was used to design the GPC system. Tuning parameters of the GPC system have been calculated using the simulation program of the packed distillation column. Using the predicted parameters, experimental and theoretical GPC systems were found very effective in controlling the overhead temperature. Dynamic matrix control (DMC) system based on a nonparametric model has been used to track the overhead temperature of the packed distillation column. For this purpose, a nonparametric model known as the dynamic matrix was determined using the reaction curve method. A step change in heat input to the reboiler was applied to the manipulated variable and the temperature of the overhead product was observed. After that, the dynamic matrix was used to design the DMC system. Several calculations have been done to define the DMC control parameters. The best values of the tuning parameter were used to realize the DMC system for controlling the overhead temperature experimentally and theoretically. In the presence of some disturbances, the DMC system gives oscillation and offset in experimental studies.     

Organic Silanes and Titanates as Processing Additives for Injection Molding of Ceramics

Organic silanes and titanates were added to a system of polyethylene and silicon nitride intended for injection molding and to a model system of paraffin oil and silicon nitride. The effect of the additions on viscosity was studied. Results from the model system agree comparatively well with the results from the system intended for injection molding. The model system can be used for screening tests. A glycidoxytrimethoxysilane reduces the viscosity of the polyethylene-silicon nitride system. In combination with tetrabutyl titanate, the effect is more pronounced.     

综合可靠性优化的化工过程参数优化

首先针对化工过程进行参数优化过程,考虑系统可靠性问题,提出了一种综合可靠性优化的参数优化模型,利用系统可用性对过程产品产量进行修正,从而将系统可用性加入到过程模型当中。其次在优化过程中。为了避免因过程模型太复杂而导致计算量大的问题,提出了结合Unisim模拟软件的优化实现方法,利用Unisim计算每次迭代过程中的过程模型和目标函数值,直至优化过程收敛。最后将以上方法应用在某天然气处理过程中。结果表明：综合可靠性优化的参数优化模型,提高了化工过程的经济效益;基于Unisim的优化过程,不需要简化过程模型,能简单、快速、有效地得到优化结果。     

Effect of dual-initiator on low temperature curing of unsaturated polyester resins

In low temperature composite manufacturing processes, a major concern is how to control the resin gel time and cure time and how to achieve a high resin conversion with low residual volatile organic chemicals. In this study, a cobalt promoter catalyzed dual-initiator system was used to control the reaction rate and resin conversion of unsaturated polyester resins. A mechanistic kinetic model was developed to predict the reaction kinetics with dual initiators. This model can be used to simulate the isothermal and dynamic reaction rate and conversion profiles. It can also be utilized to predict the effect of promoter concentration on UP resin cured at low temperatures. The dual-initiator system was applied in the vacuum-assisted resin transfer molding process at room temperature. The kinetic model, in conjunction with the heat transfer analysis, was able to successfully predict the temperature profiles during the molding processes.     

大型石化企业管道管理系统的设计和实现

应用关系型数据库规范化理论设计了石化企业管道管理系统的数据库结构，采用Mass SQL Server6.5数据库系统的库结构，用PowerBuilder6.0语言编制数据库管理系统和用户界面，并应用大量的SQL结构化查询语言作为数据库的处理工具。采用了客户机/服务器模式建立企业局域网络系统。系统采用了菜单系统和以生产流程图为界面的图形两种界面查询方式，在图形界面上，用户能对形象的图形进行操作，易于定位、使用方便。     

On developing a novel mixed-unit microparticle system for controlled release

In this study, uniform microparticles were prepared using the highly efficient microfluidic spray drying technology, and then a flexible controlled release mixed-unit microparticle system was developed to meet various needs. A mathematical drug release model of the mixed system was established and two mixed formulations were used to testify the predictive ability when initial parameters were given. Results have proved that the proposed model could precisely predict the release rate of tested samples. In conclusion, the novel system for controlled release may provide a new option for modified release drugs and may have a good prospect in the industrial application.     

不同含水率对油水体系中液滴分布预测模型的影响

油水分散系中,求解分散相液滴的分布有十分重要的研究意义。目前一般通过求解群体平衡方程(PBE)来计算分散相的分布,常用两区域模型(叶轮区域和环流区域)进行求解,但在求解过程中发现随着油包水分散体系中含水率的升高,预测结果偏离实验结果。本文通过采用计算流体力学(CFD)的方法,用商业软件FLUENT模拟发现,油包水分散系中随着含水率的升高高能量耗散区(叶轮区)在减小,水包油分散系中随着含水率的升高高能量耗散区(叶轮区)在增大。     

基于立磨选粉机颗粒分级过程的数学建模研究

通过立磨粉磨中试试验平台开展试验,对比分析不同系统风量和选粉机转速条件下选粉机分级性能的变化规律.利用正态分布的累积分布函数,将选粉机操作参数与不同粒径颗粒的捕集概率关联.采用系统风量和选粉机转速工况变化的试验数据拟合出模型中的均值和方差,建立可定量分析系统风量、选粉机转速与颗粒部分分级效率之间关系的数学模型.经验证回...     

On-line identification of interacting two-tank system

In order to demonstrate the effectiveness of the process identification algorithm, on-line parameter estimator is evaluated experimentally by using two-tank system with interaction. On-line parameter estimator used in this paper is based on a recursive parameter estimation algorithm. MIMO linear, bilinear and quadratic models based on ARMA model are used to identify two-tank system. A quadratic model for two-tank system with interaction is developed to confirm the propriety of MIMO quadratic model used in identification of two-tank system. The results of on-line identification experiments on the two-tank system show that the estimated parameters of each model converge and the output tracking errors are bounded by disturbance bound. But, the quadratic model showed the best convergence.     

基于不确定蒸汽需求和设备故障的锅炉系统随机规划设计

公用工程系统中锅炉系统设计不仅要考虑锅炉应对发生的故障的可靠性,还要保证系统具有一定应对蒸汽需求的波动的可操作性。本研究针对满足不确定蒸汽需求和考虑设备故障的锅炉系统设计,提出基于数学规划法的设计模型：对生产过程波动引起的不确定蒸汽需求以概率表达,采用Markov模型分析锅炉故障,表达为以一定概率发生的不确定参数。优化模型采用二阶段随机规划策略对蒸汽需求不确定波动和锅炉故障实现引起的约束违背进行补偿,以降低不确定变量对目标函数和约束条件的影响。以年总费用最小为目标,建立混合整数线性模型（MILP）,实现锅炉系统配置,设备模式确定以及应对蒸汽需求波动和设备故障发生的补偿操作的优化设计。     

TE过程闪蒸罐双时间尺度建模与动态特性分析

闪蒸罐是工业常用的化工单元设备, 在对其进行动态机理建模时, 气相物质的动态特性方程被拟稳态处理转化为稳态代数方程, 而液相仍为微分方程。由此一来, 与气相相关的压力的真实动态信息无法得到, 而是完全依赖于液相相态的变化。基于闪蒸罐的化工动态学机理和“拟稳态”的系统特点, 通过增加快变量的动态物料守恒关系式, 还原系统的气相快暂态过程, 建立了TE过程闪蒸罐的双时间尺度全阶模型。利用奇异摄动方法将全阶模型精确求解后, 与拟稳态模型进行了仿真对比;最后, 设计了全阶模型的压力控制回路, 得到很好的控制效果, 验证了建模方法的合理性和工业应用价值。     

APPLICATION OF MULTIVARIABLE NONLINEAR ADAPTIVE GENERIC MODEL CONTROL TO A PACKED DISTILLATION COLUMN

Nonlinear adaptive generic model control and self-tuning PID control systems were applied to control the top and bottom product temperature of a packed distillation column separating methanol-water mixture. In the first control algorithm, an adaptive generic model control (AGMC) structure was proposed for dual temperature control of the system. In the second control algorithm, nonlinear self tuning PID (NLSTPID) control based on pole-placement technique was used to control the same system. For NLSTPID control purposes pseudo random binary sequence (PRBS) signal and recursive identification algorithm were used to estimate the relevant parameters of a polynomial NARMAX model. In this work, real-time application has been carried out. In both dynamic and control studies, perturbations in feed composition were utilized as the disturbance, and the reboiler heat duty and the reflux ratio were selected as the manipulated variables. The control performances have been obtained by using ISE and, in general, AGMC results were better than those of the STPID control algorithm.     

Modeling,simulation and structural analysis of a fluid catalytic cracking (FCC) process

Fluid catalytic cracking (FCC) is an important chemical process that is widely used to produce valuable petrochemical products by cracking heavier components. However, many difficulties exist in modeling the FCC process due to its complexity. In this study, a dynamic process model of a FCC process is suggested and its structural observability is analyzed. In the process modeling, yield function for the kinetic model of the riser reactor was applied to explain the product distribution. Hydrodynamics, mass balance and energy balance equations of the riser reactor and the regenerator were used to complete the modeling. The process model was tested in steady-state simulation and dynamic simulation, which gives dynamic responses to the change of process variables. The result was compared with the measured data from operating plaint. In the structural analysis, the system was analyzed using the process model and the process design to identify the structural observability of the system. The reactor and regenerator unit in the system were divided into six nodes based on their functions and modeling relationship equations were built based on nodes and edges of the directed graph of the system. Output-set assignment algorithm was demonstrated on the occurrence matrix to find observable nodes and variables. Optimal locations for minimal addition of measurements could be found by completing the whole output-set assignment algorithm of the system. The result of this study can help predict the state more accurately and improve observability of a complex chemical process with minimal cost.     

Optimisation of Detergent Ingredients for Stain Removal Using Statistical Modelling

Artificially soiled test fabrics are widely used to study the cleaning performance of detergents formulations. In this study, artificial soiled cotton test fabrics were prepared in the laboratory using carbon black as a model soil. Design of experiments was used to optimise the concentration of detergent ingredients for stain removal. A multi‐factorial analysis of variance was used to model the effect of sodium dodecylbenzene sulfonate, nonylphenol ethoxylate, sodium silicate, sodium citrate and sodium carbonate as builders on soil removal. A colourimetric evaluation using the CIELAB system was used to measure soil removal. In general, performance increases with increasing concentration of surfactant, silicate and soda ash.     

APPLICATION OF MULTIVARIABLE NONLINEAR ADAPTIVE GENERIC MODEL CONTROL TO A PACKED DISTILLATION COLUMN

Nonlinear adaptive generic model control and self-tuning PID control systems were applied to control the top and bottom product temperature of a packed distillation column separating methanol-water mixture. In the first control algorithm, an adaptive generic model control (AGMC) structure was proposed for dual temperature control of the system. In the second control algorithm, nonlinear self tuning PID (NLSTPID) control based on pole-placement technique was used to control the same system. For NLSTPID control purposes pseudo random binary sequence (PRBS) signal and recursive identification algorithm were used to estimate the relevant parameters of a polynomial NARMAX model. In this work, real-time application has been carried out. In both dynamic and control studies, perturbations in feed composition were utilized as the disturbance, and the reboiler heat duty and the reflux ratio were selected as the manipulated variables. The control performances have been obtained by using ISE and, in general, AGMC results were better than those of the STPID control algorithm.     

丁酮肟-水-异辛醇物系液液相平衡的研究

在甲基三丁酮肟基硅烷的生产过程中会产生部分含丁酮肟的废水,用萃取方法可回收丁酮肟。为获得萃取工艺所需的基础数据,在常压、60℃温度下,以工业实际废水为物料,进行液液相平衡实验,用拟三元方法处理丁酮肟-水-异辛醇三元体系的液液相平衡数据,获得了三元体系平衡相图。实验数据用非随机两相液体(NRTL)模型进行了关联,得出了该三元体系的NRTL模型参数。将实验数据与关联结果进行比较,结果表明,NRTL模型能对该三元体系进行较准确的关联。     

窑系统有害组分挥发凝聚循环模型的建立和探讨

在水泥熟料的生产中,经常采用旁路放风的方法排出一部分窑气来控制有害组分的含量。为了确定最小放风量,建立了一个水泥窑系统有害组分挥发凝聚循环模型,并对有害组分的挥发率,旁路放风的边际效果,模型的优化和改进等进行了讨论。另外还介绍另一种思路建立的模型,并结合实际数据对两个模型进行了比较和检验。