Roll Mill Cleaning for Superabsorbent Polymer Production

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Solution Overview

Problem

Existing processes for producing superabsorbent polymer particles face challenges in effectively cleaning roll mills used for grinding dried polymer gel, leading to inefficiencies and potential contamination.

Innovation Solution

A process involving polymerization of a monomer solution containing partially neutralized acrylic acid, crosslinker, and initiator, followed by drying and grinding with a roll mill. The roll mill cleaning procedure includes monitoring deflection and power consumption, reducing feed rate, stopping feed if necessary, adjusting gap width, and restarting feed when conditions improve.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If the roll mill operates continuously at normal feed rate, then productivity is maintained, but fouling accumulates on the rolls reducing cleaning efficiency

Engineering Contradiction:
Improvecontinuous operation capabilityVSAvoidfouling accumulation
Core Design Contradiction:
ProductivityVSObject-affected harmful factors

Solution Approach 1:

The patent implements periodic cleaning cycles interspersed with production runs. The roll mill operates at normal feed rate during production, then periodically switches to cleaning mode by reducing feed rate and adjusting gap width. This periodic alternation between production and cleaning actions prevents continuous fouling accumulation while maintaining overall productivity.

Inventive Principle:
Principle #19Periodic action

Solution Approach 2:

The cleaning process utilizes parameter changes in the roll mill operation. By reducing the feed rate and adjusting the gap width between rolls, the system creates conditions that facilitate fouling removal. These parameter changes transform the roll mill from production mode to cleaning mode, enabling effective fouling reduction without stopping the overall process.

Inventive Principle:
Principle #35Parameter changes

2Object-affected harmful factors

If the feed rate is reduced to clean the roll mill, then cleaning efficiency improves, but productivity decreases

Engineering Contradiction:
Improvefouling reductionVSAvoidproduction rate
Core Design Contradiction:
Object-affected harmful factorsVSProductivity

Solution Approach 1:

The system performs cleaning actions periodically rather than continuously. By interspersing cleaning cycles with production runs, the patent maintains overall productivity while achieving effective fouling reduction. The periodic nature allows the system to alternate between maximizing production and maximizing cleaning effectiveness.

Inventive Principle:
Principle #19Periodic action

Solution Approach 2:

The patent applies preliminary cleaning actions before fouling becomes excessive. By monitoring parameters like deflection and power consumption, the system identifies optimal moments to intervene with cleaning actions. This preliminary approach prevents severe fouling buildup, allowing faster return to production and minimizing overall productivity loss.

Inventive Principle:
Principle #10Preliminary action

3Object-affected harmful factors

If the gap width is increased to remove material from rolls, then cleaning effectiveness improves, but particle size distribution may be affected

Engineering Contradiction:
Improvematerial removal efficiencyVSAvoidparticle size consistency
Core Design Contradiction:
Object-affected harmful factorsVSManufacturing precision

Solution Approach 1:

The patent uses periodic gap width adjustments during cleaning cycles. By temporarily increasing the gap width during cleaning operations and then returning to the original gap width, the system achieves effective material removal while maintaining particle size consistency during production. The periodic return to original parameters ensures product quality is not compromised.

Inventive Principle:
Principle #19Periodic action

Solution Approach 2:

The roll mill gap width is made dynamically adjustable rather than fixed. During cleaning cycles, the gap width can be increased to facilitate material removal. During production, the gap width returns to the optimized value for consistent particle size. This dynamic adjustment allows the system to optimize for different operational modes without compromising overall manufacturing precision.

Inventive Principle:
Principle #15Dynamics

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 approach improves the cleaning efficiency of roll mills, reduces fouling, and ensures consistent production of high-quality superabsorbent polymer particles by effectively managing feed rates and gap widths.

Implementation Method 1

grinding the dried polymer gel with a roll mill

Methodology Applied
Scientific EffectMechanical force: Mechanical Force

Implementation Method 2

polymerization of a monomer solution, comprising a) partially neutralized acrylic acid, b) at least one crosslinker, and c) at least one initiator

Methodology Applied
Scientific EffectPolymerization: Chemical Bonding

Implementation Method 3

drying the resulting polymer gel

Methodology Applied
Scientific EffectEvaporation: Evaporation

Data Source

PatentEP3931239B1Process for producing superabsorbent polymer particles
Publication Date: 2025.02.19 BASF SE

AI summary

The invention relates to a process for producing superabsorbent polymer particles, comprising polymerization of a monomer solution, drying the resulting polymer gel and grinding the dried polymer gel with a roll mill, wherein the rolls of the roll mill are cleaned by reducing the feed rate to the roll mill, and if the deflection and/or the power consumption increases above a setpoint, operating the roll mill with reduced feed, and increasing the feed rate to the roll mill.