Academia

In this paper, the heat transfer in polymer reactors has been investigated. The study of various methods of heat transfer in jacketed agitated vessels and the impact of altering different agitators on the heat transfer are indicated. A computer program is developed to calculate the heat transfer parameters and the heat duty required for each case. The PVC polymer reactor in the Egyptian Petrochemical Company is chosen as a case study. This reactor is modeled by Microsoft Excel and simulated by a VisiMix simulation program version turbulent SV. In addition, the chemical reaction is modeled by Aspen HYSYS V8, and eventually the modeling results are validated with the actual design data. Meanwhile, a comparison between various heat transfer methods is generated to set the preferable design and the topmost impeller for high heat transfer conditions. Furthermore, this preferable design is adopted to analyze the alteration on its performance. The result indicates that, the retreating turbine impeller is the best for a high inside heat transfer coefficient, and the half coil jacket is the best for a maximum outside heat transfer coefficient. The performance investigation shows that this design is preferable for the optimum recommended flow velocity in the jacket of v=2.3m/s, as the outside heat transfer coefficient would increase by 31.47%. Finally, the new approach which is released by Vinnolit Uhde Company is applied and its result show that the heat duty would increase by 32% due to the installation of an inner cooler inside the reactor wall, which represents a significant stride for a high-performance polymer reactor.

Published in:
1- Thermal Science Journal - Q3
https://thermalscience.rs/pdfs/papers-2018/TSCI170914009E.pdf

2- National Library of Serbia
DOISerbia - A simulation study of heat transfer in polymerization reactors - El-Helw, Mohamed; El-Seuofy, Mohamed; Attia, Abd-El-Hamid

3- Research Gate
https://www.researchgate.net/publication/322839148_A_simulation_study_of_heat_transfer_in_polymerization_reactors

Recommendations

1. Adopt thermal modeling as a standard design and troubleshooting tool It is recommended to systematically use heat transfer and mixing simulation tools (such as VisiMix, Aspen HYSYS, or equivalent software) when designing, revamping, or troubleshooting polymerization reactors, in order to identify the optimal heat transfer configuration before plant implementation.

2. Optimize the combined choice of jacket type and agitator The selection of the heat transfer method (e.g., half-coil, dimple, or conventional jackets) and the agitator type (such as retreating-blade turbine and other impellers) should be treated as an integrated decision. The goal is to choose the combination that provides the highest overall heat transfer coefficient with acceptable pressure drop and reasonable power consumption.

3. Careful control of operating thermal conditions Special attention should be paid to the coolant flow velocity in the jacket and to the inlet coolant temperature, since the study showed that even a small increase in inlet jacket temperature can significantly reduce the available heat duty and weaken the temperature control capability of the reactor.

4. Develop internal design and operating guidelines for polymerization reactors The outcomes of this work can be used as a basis for preparing internal design standards and operating guidelines that define recommended ranges for key design parameters (jacket type, impeller size and speed, pipe diameters, flow velocities, etc.) and for thermal performance indicators of PVC polymerization reactors.

5. Improve the energy efficiency of the cooling system The enhanced heat transfer performance resulting from the optimized design should be exploited to reduce the demand for chilled water or other high-grade cooling utilities, thereby lowering the overall energy consumption and operating costs of the plant.

6. Extend the methodology to other reactors and polymer grades The same simulation and comparison approach should be extended to different polymerization reactors (other polymer grades, scales, and geometries) to investigate how changes in physical properties and process conditions affect the heat transfer performance, and to recalibrate the models accordingly.

7. Integrate model results into online monitoring and control Finally, it is advisable to link the developed thermal models with real-time plant control systems (DCS/SCADA), so that model predictions can support advanced temperature control strategies, provide early warnings of potential thermal instabilities, and assist operators in making better-informed decisions during operation.