Simulation of hydrolytic polymerization of nylon-6 in industrial reactors:Part I. Mono-acid-stabilized systems in VK tube reactors

Citation
Ak. Agrawal et al., Simulation of hydrolytic polymerization of nylon-6 in industrial reactors:Part I. Mono-acid-stabilized systems in VK tube reactors, IND ENG RES, 40(12), 2001, pp. 2563-2572
Citations number
23
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Chemical Engineering
Journal title
INDUSTRIAL & ENGINEERING CHEMISTRY RESEARCH
ISSN journal
0888-5885 → ACNP
Volume
40
Issue
12
Year of publication
2001
Pages
2563 - 2572
Database
ISI
SICI code
0888-5885(20010613)40:12<2563:SOHPON>2.0.ZU;2-U
Abstract
Nylon-6 polymerization in a VK tube (vertical column) reactor is largely no t understood because of the complex internal structure of the reactor and t he unavailability of essential industrial data on polymerization. In the pr esent study, the hydrolytic polymerization of nylon-6 has been simulated in an industrial VK tube reactor for concentrations of various species. The m odel, which assumed a flat velocity profile in the radial direction, predic ted the industrial results with high accuracy. The internal design of the r eactor appears to be responsible for getting close to plug-flow conditions inside the VK tube. An empirical relation based on temperature and pressure was used to determine the water profile along the vertical axis of the rea ctor. Because the pressure increased along the axis of the reactor and the temperature first increased and then decreased, the model predicted a lowes t water content (LWC) point at near the highest temperature point. The conc entration of water at the LWC point was found to be critical in determining the properties of the end product. The model suggested three main zones in a VK tube reactor: a very small top turbulent zone, where most of the wate r was lost, followed by a large middle zone, which was a vaporizing plug-fl ow tubular zone, and a bottom zone, which was a nonvaporizing plug-flow tub ular zone. The vaporizing zone ended and the nonvaporizing zone began where the LWC point was achieved. The small turbulent zone at the top did not ap pear to affect the end polymer properties of polymerization. This model was found to be useful in carrying out process optimization and suggesting imp rovements in VK tube designs for higher productivity.