Shiqing Zheng

The Numerical Simulation of Pneumatic Drying of Polycarbonate in Vertical Tube

Abstract The mathematical model of pneumatic drying of polycarbonate material in vertical tube was established based on particle dynamics and Eulerian multiphase fluid model. The numerical solution of the model showed a good agreement with experimental data obtained from polycarbonate pilot production on particle moisture and air humidity along the length. Analyses of influencing factors of gas inlet temperature, gas velocity and particle size on moisture of polycarbonate material along tube length were given. The distributions of radial parameters of gas velocity and particle temperature were illustrated. The model can be used for further investigation of the drying of particulate material of industry.

A superstructure model of water-using network synthesis with multiple contaminants for batch processes and its solution

Abstract The key contaminant component (KCC) is defined to establish a superstructure model of water-using network synthesis for batch process with multiple contaminants, which uses storage tanks to eliminate the time limitations for water reuse or recycle, and its mathematic programming model is established and solved by nonlinear programming (NLP) method by a two-step solution strategy. Finally, an example is illustrated to show the efficiency of this method.

Three-layer solution strategy for multi-objective process synthesis

Abstract Multi-objective process synthesis can be described as a multi-objective mixed-integer nonlinear programming (MOMINLP) problem. To solve such problem, the main goal of this work is to develop a three-layer solution strategy, which includes simulation layer, synthesis layer and decision-making layer. Simulation layer is used to simulate and analyze the process system. In synthesis layer, NSGA-II is used to deal with the process data and generate an optimized population that transfers to simulation layer. In decision-making layer, the compromise solution is generated. The computer user interface is developed to support the data transmission. As a case study, MDA brine treatment process is used to illustrate the proposed strategy. The rigid process model and the optimization model are presented. The non-inferior solution curve is obtained and the final results are used to design industrial process.

Thermal properties reduced models by ANN in process simulation

It’s very time-consuming to evaluate thermal properties by rigorous methods in process real-time simulation, especially when the simulated project relates to multi-units and multi-components, which takes about 70 to 80 percent of the total simulation time. We developed a new reduced method for thermal properties evaluation based on the artificial neural net(ANN), in which we established several reduced evaluation models using ANN, such as models of vapor-liquid equilibrium, models of vapor-liquid enthalpy and models of temperature calculated from given enthalpy. We used the reduced models in a dynamic distillation simulation. Compared with rigorous thermal properties models, the ANN-reduced models could save 10 to 20 times simulation time with a satisfied accuracy. The results show it’s an efficient and effective method.

Using water cascade analysis to synthesize water use network in batch process

A new method based on water cascade analysis (WCA) is presented to synthesize water use in batch process in this paper. This method includes two key steps: determine the target and design the water network. The fresh water demands for overall process or certain time intervals with and without storage tank is identified. Also the determination of overall pinch point, the storage capacity and the storage tank numbers is discussed. A two dimensional water network diagram, the time-purity level diagram, is introduced to help target and design the water network. We use two cases to illustrate the method, the results show it can achieve the optimal batch process water network efficiently.

An automatic approach to design water utilization network

Abstract This paper presents an automatic approach for the design of water utilization network(WUN). In this work, water network design is formulated as an optimization problem of network configuration and design variables, where both operating and investment cost are optimized simultaneously. Genetic Programming(GP) was used to solve the optimization problem. The encode mode to represent WUN configuration has been studied. Several general unit operations have been selected, such as column, splitter, mix, regenerate, etc., which constitute the GP function set. The primary advantage of this approach is the automatic search for potential promising alternatives without any pre-defined superstructures.

Study on multiobjective process synthesis in modular simulator environment

Abstract The goal of this paper is to propose a new multiobjcetive process synthesis strategy in modular simulator environment. This paper presents a method of interpolation to find the tradeoff curve. An example is given to validate the reliability of the algorithm finally.