Shell and Tube Heat Exchanger Inversion for Polymerization Cooling
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Solution Overview
Problem
Existing polymerization processes face inefficiencies in heat removal due to limited cooling performance of in-reactor cooling aggregates, leading to prolonged process times and economic viability issues, with external cooling circuits facing technical limits in heat exchange area exploitation and polymer deposition on heat exchanger surfaces.
Innovation Solution
A process utilizing a shell and tube heat exchanger where the polymerization mixture is cooled by flowing around the outside of the tubes, with a coolant passing through the tubes, enhancing heat transfer efficiency and reducing polymer deposition through effective flushing with cutouts on the perforated plates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If in-reactor cooling aggregates (outer shell or cooling coils) are used for heat removal, then the polymerization reaction can be temperature-controlled, but the heat removal capacity is insufficient leading to very long process times
Solution Approach 1:
The cooling function is extracted from the in-reactor cooling aggregates and implemented through an external cooling circuit with a shell and tube heat exchanger. The polymerization mixture is continuously circulated through the heat exchanger where heat is efficiently removed by the coolant flowing through the tubes, separating the cooling function from the reaction vessel and enabling much faster heat removal.
Solution Approach 2:
A hydrodynamic approach is used by continuously circulating the polymerization mixture through the external cooling circuit using a pump. This hydraulic circulation system enables rapid heat transfer by forcing the hot reaction mixture through the heat exchanger tubes where coolant flows, significantly increasing the heat removal rate compared to static in-reactor cooling.
2Productivity
If external cooling circuits with conventional heat exchangers are used to improve heat removal, then heat exchange area can be increased, but polymer deposits on the heat exchange surface reducing efficiency
Solution Approach 1:
The conventional configuration is inverted: instead of flowing the polymerization mixture through the tubes and coolant around them, the coolant flows through the tubes while the polymerization mixture flows around the outside of the tubes in the shell. This inversion prevents polymer deposition on the heat exchange surfaces by maintaining better flow characteristics and reducing fouling.
Solution Approach 2:
The continuous circulation of the polymerization mixture through the external cooling circuit serves a dual function: it removes heat efficiently while also continuously flushing the heat exchange surfaces to prevent polymer deposition. The system self-cleans through its own operating flow, maintaining heat transfer efficiency without requiring separate cleaning operations.
3Productivity
If heat exchange area is increased to improve cooling performance, then heat removal capacity increases, but apparatus costs become high
Solution Approach 1:
The use of a shell and tube heat exchanger with continuous hydraulic circulation enables highly efficient heat transfer with a compact heat exchange area. The forced flow through the external circuit creates high heat transfer coefficients that allow sufficient cooling capacity with a smaller, more cost-effective heat exchanger compared to conventional in-reactor cooling systems.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This configuration doubles the coefficient of heat transfer and significantly reduces polymer deposition, leading to improved heat exchange performance and reduced downtimes for cleaning, thereby accelerating the polymerization process and enhancing economic viability.
Implementation Method 1
the coolant is passed through the tubes of the tube aggregate and the polymerization mixture to be cooled is guided around the outside of the tubes of the tube aggregate
Implementation Method 2
the polymerization mixture is cooled by flowing around the outside of the tubes, with a coolant passing through the tubes, enhancing heat transfer efficiency
Data Source
AI summary
Higher throughput in aqueous addition polymerization is made possible by use of an external shell and tube heat exchanger operated in reverse mode, with coolant flowing through the tubes and polymerization mixture flowing through the shell around the tubes.