Track optimization method for switching cannular polypropylene production marks

Abstract

The invention discloses a track optimization method for switching cannular polypropylene production marks. The method includes establishing a dual cannular track optimization module for switching the marks during polymerization production process of polypropylene bodies, simultaneously, effectively solving an optimal control problem of the track optimization module on the basis of a control vector parameterization method of variable time scales, namely, transforming the inhomogeneous parameterized optimal control problem into a homogeneous parameterization problem by introducing standardization time variables, further transforming the homogeneous parameterization problem into a nonlinear programming problem, and then using an interior point optimization algorithm for solving, so that control parameters and time nodes can be simultaneously optimized, and optimization efficiency of switching tracks is guaranteed. According to the track optimization method, the shortest time used in switching process and the fewest transition materials are achieved on the premise that a polypropylene device is stably and safely operated by looking for optimization tracks of operation variables and index change of product performances during the process of switching the polypropylene marks, so that economic costs can be saved, and productivity effects are improved.

Description

technical field [0001] The invention relates to the field of grade switching in the polypropylene industrial process, in particular to a method for optimizing the grade switching trajectory of a ring-pipe type polypropylene production. Background technique [0002] There are a wide variety of polypropylene products, from general-purpose products to coating, spinning, extrusion and modification, covering all fields of the national economy, and the production of different product types needs to be distinguished by various resin grades. In order to meet the diversity of market demand for polypropylene resin product performance and obtain good economic benefits at the same time, polypropylene manufacturers often adopt flexible production models to arrange production. Therefore, polymerization units need to frequently switch grades according to different polymerization process conditions. However, the brand switching process presents the characteristics of strong nonlinearity, co...

AI Technical Summary

Problems solved by technology

For uniform grid optimization, more time nodes are often needed to achieve good control effects, and will not change during the optimization process, which will lead to a large-scale nonlinear programming problem

There are literatures on non-uniform grid optimization, using random methods such as genetic algorithm or differential evolution to optimize time nodes, but using such non-gradient optimization methods will greatly increase the amount of calculation

In addition, the simultaneous method has also been studied in the optimization of the brand switching trajectory. This method uses the finite element orthogonal configuration method to discretize the continuous state and the control variable, and converts it into a simultaneous nonlinear programming problem, and uses the simplified space interior point method to solve it. However, The solution scale is huge and requires a professional solver

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