Reactive Distillation Column Layout for Low-Loss Polyamide Polymerization
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Solution Overview
Problem
The volatilization of diamine during polycondensation of diacid and diamine in polyamide production leads to unbalanced carboxylic acid/amine ratios, increased production costs, and environmental pollution, while existing processes struggle with inefficient heat exchange and high operational costs.
Innovation Solution
A continuous polymerization equipment comprising an evaporator, reactive distillation column, flash drum, and polymerizer, with optimized tray configurations and heat exchangers, enables preliminary polymerization and countercurrent mass transfer to reduce diamine loss and maintain ratio balance, while using online monitoring and replenishment to adjust diamine levels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If diamine is removed from salt solution during evaporation and concentration, then water is removed and polycondensation is completed, but diamine volatilizes causing unbalanced carboxylic acid/amine ratio and increased production cost
Solution Approach 1:
The patent converts the harmful volatilization of diamine into a beneficial recycling process. The volatile diamine is captured in the reactive distillation column, condensed, and returned to the salt solution, transforming what was previously a loss into a resource recovery mechanism that maintains stoichiometric balance and reduces production costs
Solution Approach 2:
The patent implements a recovery system where diamine that would otherwise be discarded through volatilization is captured, condensed, and reused. The reactive distillation column separates and recovers diamine from the vapor phase, returning it to the liquid phase salt solution to maintain the required carboxylic acid/amine ratio
2Productivity
If diamine is removed from salt solution during evaporation and concentration, then polycondensation is completed, but volatile diamine is discharged with gas phase causing environmental pollution
Solution Approach 1:
The patent converts the harmful emission of volatile diamine into a beneficial internal recycling loop. The reactive distillation column captures the volatilized diamine in the vapor phase, condenses it, and returns it to the reaction system, transforming an environmental pollutant into a recovered chemical resource
Solution Approach 2:
The patent creates a closed system environment where volatile diamine is contained and recycled rather than discharged to the atmosphere. The reactive distillation column and associated condensation equipment form a controlled environment that prevents harmful emissions while maintaining the polycondensation process
3Ease of manufacture
If traditional batch process is used for polycondensation, then process flexibility is maintained, but heat exchange efficiency is low and operational costs are high
Solution Approach 1:
The patent transitions from batch to continuous processing, where the salt solution continuously flows through the evaporator, reactive distillation column, and heat exchangers. This continuous operation eliminates idle time between batches, maintains optimal heat exchange conditions throughout the process, and improves energy efficiency while preserving operational flexibility through controlled flow rates and temperature profiles
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 equipment ensures high-quality polyamide production with reduced losses, waste generation, and operational costs, while maintaining efficient heat exchange and minimizing environmental impact.
Implementation Method 1
removing the physical water and generated water in the system
Implementation Method 2
reactive distillation column includes a reboiler and a tray section
Implementation Method 3
enables preliminary polymerization and countercurrent mass transfer to reduce diamine loss
Implementation Method 4
preheating heat exchanger and a prepolymerization heat exchanger
Implementation Method 5
using online monitoring and replenishment to adjust diamine levels
Implementation Method 6
The tray section includes a reboiler
Data Source
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Figure 2
AI summary
A continuous polymerization equipment and a continuous polymerization process for preparing polyamide by using a diacid and a diamine. The continuous polymerization equipment includes an evaporator, a reactive distillation column, a flash drum and a polymerizer which are sequentially communicated by pipelines. The number of trays in the tray section of the reactive distillation column is in a range of 15 to 30, the distance between two adjacent trays is in a range of 400 mm to 600 mm, and the height of an overflow weir of the trays is in a range of 50 mm to 300 mm. The continuous polymerization equipment further includes a preheating heat exchanger and a prepolymerization heat exchanger. The prepolymerization heat exchanger and the reboiler are circularly communicated by the pipelines, so that material enters the preheating heat exchanger, the prepolymerization heat exchanger and the reboiler in turn through the tray, and enables continuous circulation between the prepolymerization heat exchanger and the reboiler.