Pivoting Belt Gel Application for Uniform Drying

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Solution Overview

Problem

Existing methods for producing water-absorbing polymer particles using circulating air belt dryers face challenges in achieving uniform drying and minimizing product damage, particularly due to difficulties in ensuring even coverage of the conveyor belt with aqueous polymer gel.

Innovation Solution

A process involving the application of aqueous polymer gel to the conveyor belt using a pivoting belt with specific angular velocities and pivot angles, coordinated with conveyor belt speed to achieve uniform drying and reduce product damage, while also allowing for thermal surface post-crosslinking to enhance properties.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If a circulating air belt dryer with wide conveyor belts is used to dry aqueous polymer gel, then drying capacity is improved, but uniform coverage of the conveyor belt with aqueous polymer gel becomes difficult to ensure

Engineering Contradiction:
Improvedrying capacityVSAvoiduniformity of coverage
Core Design Contradiction:
ProductivityVSManufacturing precision

Solution Approach 1:

The application process is divided into multiple sequential phases: acceleration phase, constant speed phase, and deceleration phase. The swivel belt applies gel at different speeds and angles during each phase, with the application angle varying from 0° to 45° and back to 0°, ensuring uniform distribution across the wide conveyor belt surface while maintaining high drying capacity

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The swivel belt operates with dynamic motion control, adjusting its angular velocity and application angle in real-time during the three phases. The belt speed varies from 0.5-2.0 m/s during acceleration, maintains constant speed in the middle phase, and decelerates toward the end, creating optimal gel distribution patterns across the entire conveyor belt width

Inventive Principle:
Principle #15Dynamics

2Quantity of substance

If the amount of crosslinker is increased to adjust polymer properties, then absorption capacity reaches maximum, but centrifuge retention capacity decreases

Engineering Contradiction:
Improveabsorption capacityVSAvoidcentrifuge retention capacity
Core Design Contradiction:
Quantity of substanceVSManufacturing precision

Solution Approach 1:

The patent optimizes the crosslinker concentration parameter within the range of 0.01-5% by weight of the monomer mixture. By precisely controlling this parameter and combining it with the dynamic application method, the process achieves maximum absorption capacity while maintaining adequate centrifuge retention capacity, resolving the trade-off between these two critical properties

Inventive Principle:
Principle #35Parameter changes

3Reliability

If thermal surface post-crosslinking is applied to enhance product properties, then absorption characteristics improve, but processing complexity increases

Engineering Contradiction:
Improveabsorption characteristicsVSAvoidprocessing complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent applies thermal surface post-crosslinking as a preliminary treatment before the main drying process. By pre-crosslinking the gel surface at controlled temperatures and durations, the process enhances absorption characteristics and structural stability, making the subsequent drying more efficient and the final product more reliable

Inventive Principle:
Principle #10Preliminary action

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 ensures uniform drying of water-absorbing polymer particles, reduces the degree of crosslinking, and maintains a high centrifuge retention capacity, thereby improving the absorption and processing characteristics of the final product.

Implementation Method 1

the pivoting belt starting from an end position over a first pivoting angle β1, where β1 from 8 to 24°, to an angular velocity v1 accelerated, over a second pivot angle β2, where β2 from 10 to 40°, to an angular velocity v2 braked

Methodology Applied
Scientific EffectCentrifugal force: Centrifugal Force

Implementation Method 2

drying the aqueous polymer gel obtained on a circulating air belt dryer

Methodology Applied
Scientific EffectEvaporation: Evaporation

Implementation Method 3

circulating air belt dryer

Methodology Applied
Scientific EffectConvection: Convection

Implementation Method 4

optionally thermal surface post-crosslinking

Methodology Applied
Scientific EffectThermal heating: Heating

Data Source

PatentEP2438096B1Method for producing water-absorbing polymer particles
Publication Date: 2016.01.27 BASF SE
  • EP2438096B1 patent drawingFigure 1

AI summary

The invention relates to a method for producing water-absorbing polymer particles, wherein an aqueous polymer gel is applied to the conveyor belt of a circulating air belt dryer by means of a slewing belt conveyor, and the slewing belt conveyor is accelerated starting from an end position over a first slew angle to an angular velocity v1, decelerated over a second slew angle to an angular velocity v2, and decelerated to the other end position over a third slew angle.