Joule–Thomson Effect in Mixtures Containing Polymers and Copolymers

Abstract

The objective of this study is to evaluate the Joule–Thomson effect, which occurs at a valve due to the throttling process for mixtures containing polymers and copolymers. For economic and safety reasons, it is essential to know the temperature change in industrial processes due to the pressure drop in the valve. The modeling of this phenomenon in mixtures containing polymers and copolymers, however, remains a challenge for process engineers, and the literature rarely reports studies on the subject. This work proposes a model that can directly compute temperature due to the throttling process using the concept of residual enthalpy and the perturbed-chain statistical associating fluid theory equation of state, instead of solely computing the Joule–Thomson coefficient. Systems containing poly­(ethylene-co-vinyl acetate) and low-density polyethylene were chosen as case studies because of the need for temperature control at the reactor outlet and separation processes. The model prediction was validated using industrial data, and deviations of approximately 2% between the model prediction and the experimental temperature indicate the efficiency of the proposed approach when describing the temperature due to the throttling of both systems that are being studied.

Prediction of Thermodynamic Properties of CO2 by Cubic and Multiparameter Equations of State for Fluid Dynamics Applications

“…Heating due to expansion, on the other hand, might favor side reactions and the formation of undesirable products. 37 Drilling in gas reservoirs, which operate at high temperatures and pressures, in the range where the Joule-Thomson coefficient is negative, might lead to a temperature increase due to pressure relief, and even a small increase in temperature might significantly affect the operation of surface production facilities. 28 It is possible to rewrite eq 3 in a more useful way so as to compute the Joule-Thomson coefficient: 28…”

“…13,28,3−32 This information, however, might not suffice, as the knowledge of the outlet temperature itself is required to ascertain, for example, the amount of hydrates or subproducts formed. 37 We therefore propose an approach to compute the throttling outlet temperature based on the concept of residual property. The change in enthalpy from a real state T P ( , )…”

“…The condensation caused by the expansion might form a liquid phase, which might be desired for cryogenic distillation or might not be desired as in the case of flowing fluids. Heating due to expansion, on the other hand, might favor side reactions and the formation of undesirable products . Drilling in gas reservoirs, which operate at high temperatures and pressures, in the range where the Joule-Thomson coefficient is negative, might lead to a temperature increase due to pressure relief, and even a small increase in temperature might significantly affect the operation of surface production facilities …”

“…We further propose a method for ascertaining the throttling temperature based on residual properties, which has already presented promising results when applied to a polymerization system based on PC-SAFT EOS. 37 This paper, therefore, aims to contribute to filling the gap between thermodynamics and fluid dynamics, providing a more comprehensive study of the prediction of important thermodynamic properties for the compressible flow of CO 2 and for further sCO 2 applications, covering liquid, superheated vapor and supercritical phases. The results should guide the choice regarding the best EOS for each property at given pressures and temperature conditions with acceptable accuracy and complexity.…”

“…There should be a balance between complexity and accuracy, which might be achieved by the multiparameter Huang and SP EOS. We further propose a method for ascertaining the throttling temperature based on residual properties, which has already presented promising results when applied to a polymerization system based on PC-SAFT EOS . This paper, therefore, aims to contribute to filling the gap between thermodynamics and fluid dynamics, providing a more comprehensive study of the prediction of important thermodynamic properties for the compressible flow of CO 2 and for further sCO 2 applications, covering liquid, superheated vapor and supercritical phases.…”