Ethylene-Vinyl Acetate Polymerization With Absorptive Heat Exchange
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Solution Overview
Problem
Existing methods for producing ethylene-vinyl acetate copolymers face inefficiencies in heat removal during polymerization, leading to reduced productivity and potential formation of deteriorated products due to uneven temperature distribution and scale adhesion in cooling systems.
Innovation Solution
A method involving a polymerization vessel connected to a heat exchanger where vinyl acetate is cooled to between -50°C and 23°C, absorbed by ethylene in a parallel or countercurrent flow, and then added to the reaction liquid, allowing efficient heat removal and continuous production of ethylene-vinyl acetate copolymers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a cooling jacket is used to remove heat from the polymerization reaction liquid, then the heat removal efficiency is improved, but the contact area between the cooled vessel wall and reaction liquid is limited, reducing heat removal efficiency for larger vessel volumes
Solution Approach 1:
The patent introduces a cooling coil as an intermediary heat transfer element that circulates through the reaction liquid, providing extensive surface area contact without requiring direct cooling of the vessel wall. This mediator approach solves the limitation of jacket cooling where the vessel wall contact area is insufficient for large volumes.
2Loss of energy
If a cooling coil is used to increase contact area with reaction liquid, then heat removal efficiency is improved, but retained portions form in the reaction liquid causing polymer deterioration
Solution Approach 1:
The patent utilizes fluid dynamics principles by designing the cooling coil configuration and reaction liquid circulation system to maintain continuous flow patterns. The hydraulic design ensures that reaction liquid continuously moves through the cooling coil, preventing stagnant retained portions that would cause polymer deterioration while maintaining effective heat removal.
3Loss of energy
If cooling is applied to the polymerization system, then heat removal is achieved, but the reaction liquid becomes partially low temperature causing viscosity increase and promoting liquid retention
Solution Approach 1:
The patent implements a dynamic cooling system where the cooling coil is designed to induce continuous circulation of the reaction liquid. The system maintains optimal temperature gradients along the coil length, ensuring that while cooling occurs, the induced convection currents prevent viscosity increase and liquid retention, maintaining high productivity throughout the polymerization process.
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 method enhances heat removal efficiency, improves productive capacity, and prevents scale adhesion, resulting in higher productivity and quality ethylene-vinyl acetate copolymers without significant equipment modifications.
Implementation Method 1
introducing pressurized gas containing ethylene present in a gas phase portion of the polymerization vessel into the heat exchanger; supplying vinyl acetate cooled to between -50°C and 23°C to an upper portion of the heat exchanger; flowing vinyl acetate down in the heat exchanger while absorbing ethylene
Implementation Method 2
a heat exchanger circulating a coolant; introducing pressurized gas containing ethylene present in a gas phase portion of the polymerization vessel into the heat exchanger
Implementation Method 3
flowing vinyl acetate down in the heat exchanger while absorbing ethylene; letting vinyl acetate, in which ethylene is dissolved, out of a bottom portion of the heat exchanger
Data Source
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AI summary
A method of continuously producing an ethylene-vinyl acetate copolymer in a polymerization vessel containing a reaction liquid containing ethylene, vinyl acetate, a polymerization initiator and methanol, the polymerization vessel being connected via piping to a heat exchanger circulating a coolant, the method includes the steps of: supplying ethylene, the polymerization initiator and methanol to the polymerization vessel; introducing pressurized gas containing ethylene present in a gas phase portion of the polymerization vessel into the heat exchanger; supplying vinyl acetate cooled to between -50°C and 23°C to an upper portion of the heat exchanger; flowing vinyl acetate down in the heat exchanger while absorbing ethylene; letting vinyl acetate dissolving ethylene out of a bottom portion of the heat exchanger and adding to the reaction liquid in the polymerization vessel; and taking the reaction liquid out of the polymerization vessel. This provides a method of efficiently removing heat during polymerization of an ethylene-vinyl acetate copolymer.