On‐line parameter estimation in a high‐pressure low‐density polyethylene tubular reactor

Abstract

The high throughput and operating cost of the

Detailed Molecular Structure Modeling – A Path Forward to Designing Application Properties of ldPE

“…Anyway, it is obvious to use such tools for design and layout of new reactors. [7] On this basis, Pladis et al [8] proposed a model for a compartmentalized autoclave. However, the base is a standard tank in series model with back flow.…”

“…Mechanisms that are even more complicated may be considered when modeling copolymerizations considering the detailed polymer microstructure as shown by Busch et al [18] To consider technical aspects as the complex heat exchange in tubular technical reactors the concept of horizontal model integration may be used combining PREDICI with proprietary software as demonstrated by Mähling et al [1] The quality of information that can be accessed by this concept exceeds that of prior work that used the method of moments. [2,7] Temperature and pressure profiles are well captured as well as conversion and species concentrations. Superior is that this technique provides the full rigorously computed MWD and averaged information about the molecular microstructure.…”

Molecular weight distribution in low-density polyethylene polymerization; impact of scission mechanisms in the case of a tubular reactor

“…The polymerization conditions vary per polymerization process. The usual operation temperature for an autoclave is over 230 • C, while that for a tubular reactor it is below 300 • C. In both processes, the reactor temperature is carefully maintained far below the ceiling temperature, 340 • C (Kiparissides et al, 1996). Even though initiation reaction by thermal decomposition of ethylene is observed, its rate is negligible compared to that by chemical initiation.…”

“…An overview is given in Zabisky et al (1992) and Kiparissides et al (1996). The most comprehensive kinetic data for ldPE polymerization can be found in two recent publications: Kiparissides et al (1993) and Busch (2001a,b).…”

“…The annual consumption of polyethylene family is over 35 million tons over the world for low price and easy processability, and it seems to continue to grow by the new process technologies (Peacock, 2000). Driven by commercial interest, various modeling studies have been performed until now to optimize the productivity in macro-scale, since modeling study of ldPE tubular polymerization started in 1960s (Goldstein and Amundson, 1965;Zabisky et al, 1992;Kiparissides et al, 1996;Tsai and Fox, 1996). Even though the e ect of scission models on molecular weight distribution (MWD) has been included in the open literature recently, most of the references considered the scission reaction as simple linear scission.…”