Vertical Multistage Reactor Agitation via Gas Injection
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Solution Overview
Problem
Conventional methods for producing high molecular weight polyamides in vertical multistage reactors face challenges such as degradation, gel build-up, and the need for mechanical agitation, which complicates reactor design, increases costs, and limits production output due to the requirement for large and complex agitators.
Innovation Solution
A continuous process using a vertical multistage reactor with counter-current flow of molten dicarboxylic acid and diamine, where steam or inert gas is injected to agitate the polyamide mixture, reducing the need for mechanical agitation and allowing for larger reactor sizes and increased output.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If mechanical agitation is used to homogenize the molten polyamide mixture, then mixing efficiency is improved, but reactor complexity and device complexity increase due to the need for large and complex agitators
Solution Approach 1:
The patent replaces the mechanical agitation system with a chemical reaction-based mixing mechanism. The polyamidation reaction between diacid and diamine generates heat and produces water, which naturally circulates and mixes the molten mixture without requiring mechanical agitators. This substitution eliminates complex mechanical components while achieving effective homogenization of the reaction mixture.
Solution Approach 2:
The reaction system itself provides the mixing function through the exothermic polyamidation reaction. The heat generated by the reaction creates natural convection currents that continuously circulate and mix the molten polyamide mixture, making the system self-mixing without external mechanical intervention.
2Productivity
If large mechanical agitators are used to handle increased reactor sizes, then mixing capability is maintained, but capital expenditure and device complexity increase
Solution Approach 1:
The patent eliminates the need for scaling up mechanical agitators by replacing them with a chemical reaction-driven mixing system. The polyamidation reaction's inherent heat generation and water production create natural circulation patterns that scale automatically with reactor size, allowing increased production output without proportionally increasing agitator complexity or capital expenditure.
Solution Approach 2:
The patent changes the mixing mechanism from mechanical force to thermal convection driven by the exothermic reaction. As reactor size increases, the total heat generation increases proportionally, maintaining effective mixing throughout the larger volume without requiring larger or more complex mechanical agitators.
3Ease of operation
If high temperatures are used to maintain components in molten form, then flowability is improved, but product degradation increases
Solution Approach 1:
The patent employs continuous counter-current flow of diacid and diamine through multiple reaction stages, maintaining steady-state temperatures that are sufficient for molten flow but controlled to prevent degradation. The continuous removal of water product and steady supply of reactants maintain optimal temperature conditions throughout the process.
Solution Approach 2:
The patent applies different temperature conditions to different stages of the reactor. Early stages operate at temperatures optimized for reaction initiation and water removal, while later stages operate at lower temperatures suitable for high molecular weight polymer formation, thereby preventing thermal degradation in the final product while maintaining flowability in earlier stages.
4Productivity
If water is removed by evaporation at elevated pressure, then polyamide molecular weight is increased, but excessive heat is required causing discoloration and chemical degradation
Solution Approach 1:
The patent utilizes the phase transition of water from liquid to vapor during the polyamidation reaction to drive the equilibrium toward high molecular weight polyamide formation. The water produced by condensation is continuously evaporated and removed, shifting the reaction equilibrium without requiring excessive heat input or post-evaporation heating, thereby avoiding discoloration and degradation.
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 process simplifies reactor design, reduces energy requirements, and enhances production efficiency by minimizing impurities and colorants, while allowing for larger reactor sizes and increased output without the need for large mechanical agitators, thus improving heat transfer and reliability.
Implementation Method 1
agitating the liquid phase material P by injecting a gaseous stream C consisting or consisting essentially of steam, or at least one inert gas, or a mixture of steam and at least one inert gas into the reactor below the final stage of the reactor through the liquid phase material P
Implementation Method 2
injecting a gaseous stream C consisting or consisting essentially of steam, or at least one inert gas, or a mixture of steam and at least one inert gas into the reactor below the final stage of the reactor through the liquid phase material P
Data Source
Figure 1
Figure 2a~2b
Figure 3a
AI summary
A continuous process for the manufacture of a polyamide, the process comprising the steps of: (i) flowing a stream A comprising a molten dicarboxylic acid, or a molten dicarboxylic acid-rich mixture comprising a dicarboxylic acid and a diamine, through a first stage and at least one more reaction stage of a vertical multistage reactor, wherein the first stage is at the top of the reactor; (ii) counter-currently flowing a stream B comprising a diamine as either a vapour or a diamine-rich liquid through at least one of the stages below the first reaction stage of said vertical multistage reactor; (iii) accumulating a liquid phase material P comprising polyamide at and/or below the final stage of said reactor; wherein said reactor is equipped with internal features suitable for effecting contact between counter-currently flowing streams A and B; and wherein said process further comprises the step of agitating said liquid phase material P by injecting a gaseous stream C comprising steam, or at least one inert gas, or a mixture of steam and at least one inert gas into the reactor at or below the final stage of the reactor. The invention further provides a vertical multistage reactor configured to implement said process.