Model-Based Optimization of the Cooling System of an Industrial Tubular LDPE Reactor

Abstract

The model-based optimization of the cooling system of an industrial tubular reactor for the production of lowdensity polyethylene (LDPE) is studied in this paper. First a detailed reactor simulator is presented. Second, a series of wellposed optimization problems are formulated and solved. To this end, the optimization problems are presented with an increasing number of degrees of freedom. Moreover, economic cost functions consisting of conversion and energy terms are derived and constraints due to operational and safety reasons are added. The degrees of freedom involve parameters such as the initiator feed rates, the cooling water temperatures, and the switching position between hot and cold cooling water. The optimization results indicate that a dual water circuit operating at a low and a high temperature allows significant improvements in conversion with respect to the reference case of a single temperature circuit, while maintaining similar molecular characteristics.

Dynamic optimization of low-density polyethylene production in tubular reactor under thermal safety constraint

“…For the thermal safety constraint study, usually, the maximum peak temperature is lowered to facilitate the safety tolerance value [19]. For this reason, the monomer conversion is reduced as well since it is proportionally related to reaction temperature [29]. By tracking the optimal TJ trajectory obtained in Problem 2, the on-spec of LDPE grade can be be produced within termal safety-precaution.…”

Advances in Mathematical Modeling of Gas-Phase Olefin Polymerization

“…By referring to Equations (3) until 57, a method of moments and population balances, which are in form of ordinary differential equation (ODEs), were used to build and simulate the kinetics model with the aim of studying the dynamic behavior of the olefin polymerization reaction in a fluidized bed reactor, horizontal-stirred-bed reactor, vertical-stirred-bed reactor, tubular reactor, extruder, and autoclave reactor via two types of reaction mechanisms, namely, coordination and free-radical mechanisms. For the olefin polymerization via a coordination mechanism, Equations (58) to (60) are used to calculate the polydispersity index, number average molecular weight, and the weight average molecular weight, respectively.…”