Preheated Polymer Dispersion Spray Drying
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Solution Overview
Problem
Existing spray drying processes for aqueous polymer dispersions are inefficient, particularly for temperature-sensitive materials, as they require high drying air temperatures that can damage the polymers and result in poor powder quality and stability.
Innovation Solution
Preheating the aqueous polymer dispersion to 100° C. to 200° C. before atomization in a nozzle atomization dryer, ensuring the pressure does not cause boiling, allows for improved drying efficiency and powder quality without detrimental effects on the polymer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If high drying air temperatures are used in spray drying, then drying efficiency is improved, but polymer damage occurs and powder quality deteriorates
Solution Approach 1:
The polymer dispersion is preheated to a temperature close to its dew point before atomization, so that the majority of water evaporation occurs during the atomization and initial drying phase. This preliminary heating action reduces the need for subsequent high-temperature drying, thereby maintaining drying efficiency while avoiding polymer damage from excessive temperatures.
Solution Approach 2:
The process changes the temperature parameters dynamically: the dispersion is heated to a specific temperature range (close to dew point) before atomization, and the drying air temperature is controlled to be sufficiently high to ensure rapid drying but not excessively high to cause polymer damage. This parameter optimization resolves the contradiction between drying efficiency and polymer protection.
2Quantity of substance
If high drying air temperatures are used, then evaporation rate increases, but powder stability and redispersibility deteriorate
Solution Approach 1:
By preheating the dispersion to near dew point temperature before atomization, the process ensures that evaporation occurs primarily during the atomization phase when droplets are small and surface area is large. This preliminary evaporation action achieves high water removal efficiency while avoiding the need for excessive drying temperatures that would harm powder stability and redispersibility.
Solution Approach 2:
The process optimizes temperature parameters by heating the dispersion to a controlled temperature close to its dew point, and controlling the drying air temperature to be high enough for efficient evaporation but not excessively high to compromise powder stability. This parameter control resolves the contradiction between evaporation rate and powder quality.
3Loss of energy
If the dispersion is heated to high temperature before atomization, then energy for evaporation is reduced, but boiling may occur
Solution Approach 1:
The process heats the dispersion to a temperature close to but not exceeding the dew point temperature, optimizing the balance between reducing evaporation energy requirements and avoiding boiling. By controlling the temperature parameter within this specific range, the process recovers energy efficiently while preventing the harmful effect of boiling during atomization.
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 enhances throughput and product quality by reducing the energy needed for evaporation, minimizing agglomeration, and maintaining the stability and redispersibility of the polymer powders, even for temperature-sensitive materials.
Implementation Method 1
the aqueous polymer dispersion (feed), before being atomized, is preheated under pressure to a temperature of 100° C. to 200° C.
Implementation Method 2
is atomized at this temperature, the pressure being set such that the aqueous phase of the polymer dispersion (feed) does not boil at the temperature selected
Implementation Method 3
Process for preparing dispersion powders by spray drying of aqueous polymer dispersions
Data Source
AI summary
The invention provides a process for preparing dispersion powders by spray drying of aqueous polymer dispersions of polymers of one or more ethylenically unsaturated monomers selected from the group encompassing vinyl esters, methacrylic esters, acrylic esters, olefins, dienes, vinylaromatics, and vinyl halides with a drying gas in a nozzle atomization dryer, characterized in that the aqueous polymer dispersion (feed), before being atomized, is preheated under pressure to a temperature of 100° C. to 200° C. and is atomized at this temperature, the pressure being set such that the aqueous phase of the polymer dispersion does not boil at the temperature selected.