Grade transition control method of polyethylene production process based on two-layer hierarchical structure

A brand switching and control method technology, applied in the direction of adaptive control, general control system, control/regulation system, etc., can solve the problems of not considering the online trajectory deviation detection and updating mechanism, and not applying the brand switching control field

Active Publication Date: 2013-06-26
ZHEJIANG UNIV
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Problems solved by technology

Another method similar to single-layer DRTO is the two-layer DRTO strategy. The upper and lower controllers work on different time scales. This architecture can handle different types of dynamics and uncertainties, but most...

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  • Grade transition control method of polyethylene production process based on two-layer hierarchical structure
  • Grade transition control method of polyethylene production process based on two-layer hierarchical structure
  • Grade transition control method of polyethylene production process based on two-layer hierarchical structure

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Embodiment Construction

[0047] The present invention will be further described below in conjunction with the accompanying drawings.

[0048] refer to Figure 1-Figure 4 , based on the double-layer hierarchical structure grade switching control method in the polypropylene production process, the specific implementation method is as follows:

[0049] (1) Take the 2# double-ring tubular polypropylene device of a branch of Sinopec (such as figure 1 Shown) two grades (film grade S38F and drawing grade T30S, defined as grades A and B) are the objects (see Table 1). Based on the actual production conditions on site, determine the switching steady-state point and switching constraints of each brand (see Table 2), and give the double-loop pipe product quality index cumulative melt index switching qualification range of ±5%, and at the same time give the aggregation operation variable switching range Value and control increment constraints (see Table 3). In addition, the dynamic mechanism mathematical model...

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Abstract

The invention discloses a grade transition control method of polyethylene production process based on a two-layer hierarchical structure. The grade transition control method includes upper-layer polyethylene grade transition trajectory dynamic optimization, trajectory tracking predictive control and trajectory deviation detection of lower-layer and online updating mechanism. By combining the polyethylene grade transition trajectory dynamic optimization and the trajectory tracking predictive control on the basis of the two-layer hierarchical structure, the polyethylene production grade transition control strategy is designed; a method of controlling vector parameterization is adopted for the transition trajectory dynamic optimization; and quick tracking control is realized by model predictive controller adopted for a trajectory tracking controller. Meanwhile, a deviation detection mechanism is introduced to update optimized trajectory online. By the aid of the grade transition control method, affection of uncertain features and disturbance during polyethylene production grade transition process can be overcome; grade transition close-loop control is realized; online trajectory accuracy of an optimized trajectory is improved; economic cost of the polyethylene grade transition process is saved; and comprehensive benefits of enterprises are improved.

Description

technical field [0001] The invention relates to the field of grade switching in the polypropylene industrial process, in particular to a control method for grade switching in the polypropylene production process based on a double-layer hierarchical structure. Background technique [0002] There are many kinds of polypropylene products. In order to meet the market demand and obtain good economic benefits, polypropylene manufacturers often adopt flexible production mode to arrange production. Therefore, the polymerization device needs to switch grades frequently according to different polymerization process conditions. In the actual grade switching process, the method of offline switching trajectory optimization can bring better guidance to field engineers and operators, and there have been many successful application cases so far. However, due to the complex operation of the actual process, uncertain factors such as changes in working conditions, and the existence of process ...

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Application Information

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IPC IPC(8): G05B13/04
Inventor 娄海川谢磊苏宏业古勇孙培荣冈
Owner ZHEJIANG UNIV
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