Spray Nozzle Coating Water-Absorbing Polymer Particles
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Solution Overview
Problem
Existing processes for producing water-absorbing polymer particles face challenges in achieving uniform coating with high permeability and low dust content, while also being prone to disruption and agglomeration.
Innovation Solution
A process involving the use of a spray nozzle to coat water-absorbing polymer particles with a liquid below the product bed surface in a mixer with moving tools, utilizing a two-substance nozzle for atomization and adjusting parameters like fill level, temperature, and residence time to ensure uniform coating and prevent agglomeration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a liquid is sprayed onto water-absorbing polymer particles using a spray nozzle, then the coating uniformity and permeability are improved, but the particles may agglomerate and the process becomes prone to disruption
Solution Approach 1:
A fluidizing gas is introduced as an intermediary medium between the spray nozzle and the polymer particles. The gas fluidizes the particle bed, creating a fluid-like state that prevents agglomeration during liquid spraying while ensuring uniform coating distribution. This mediator enables the spray process to proceed reliably without direct particle-particle contact that would cause clumping.
Solution Approach 2:
The process controls multiple parameters including gas flow rate, liquid spray rate, temperature, and residence time to maintain optimal conditions. By dynamically adjusting these parameters, the system prevents agglomeration while achieving uniform coating. The fluidizing gas velocity is specifically controlled to keep particles suspended without causing excessive movement or clumping.
2Manufacturing precision
If the liquid temperature is lower than the polymer particle temperature, then the coating quality improves, but the process complexity increases
Solution Approach 1:
The polymer particles themselves serve as the heating source for the liquid coating. As the cooler liquid contacts the warmer particles during the coating process, the particles naturally transfer heat to the liquid, warming it to the optimal coating temperature. This self-heating mechanism eliminates the need for external heating systems or complex temperature control apparatus.
3Manufacturing precision
If the spray nozzle is positioned below the product bed surface, then coating uniformity improves, but the risk of nozzle blockage and process disruption increases
Solution Approach 1:
The fluidizing gas acts as a protective intermediary that prevents liquid from accumulating and blocking the spray nozzle. By maintaining particles in a fluidized state, the gas ensures continuous movement around the nozzle area, preventing liquid pooling and potential blockage while allowing the nozzle to remain positioned below the surface for optimal coating.
Solution Approach 2:
The fluidizing gas creates continuous periodic movement of particles around the spray nozzle. This constant motion prevents liquid from stagnating at the nozzle opening, thereby preventing blockage. The periodic particle movement ensures that the nozzle remains clear while maintaining its optimal position below the product bed surface.
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
The process achieves uniformly coated water-absorbing polymer particles with high permeability and low dust content, maintaining continuous operation without disruption, and enhancing properties like centrifuge retention capacity and absorbency under load.
Implementation Method 1
EP 1 191 051 A2 describes spray nozzles with a wide spray angle for use in the postcrosslinking of water-absorbing polymer particles
Implementation Method 2
a liquid being sprayed onto the water-absorbing polymer particles by means of at least one spray nozzle in a mixer with moving mixing tools
Implementation Method 3
The postcrosslinker solution to be sprayed on preferably has a lower temperature than the initially charged water-absorbing polymer particles
Data Source
AI summary
A process for preparing water-absorbing polymer particles by spraying a liquid below the product bed surface by means of at least one spray nozzle in a mixer with moving mixing tools.