Pulp Drying Control via Predictive Index for Web Break Prevention

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Solution Overview

Problem

The cellulose pulp drying process is prone to unexpected shutdowns due to web breaks, which are time-consuming to repair and costly, necessitating a method to predict and prevent such issues.

Innovation Solution

A method involving the measurement of process parameters in previous steps to calculate a drying predictive index, allowing for the determination and application of optimized drying control parameters to prevent web breaks and enhance throughput.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If web speed is increased to improve productivity, then throughput of the drying line is improved, but the risk of web breaks increases

Engineering Contradiction:

Improvethroughput of drying lineVSAvoidrisk of web break

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The system performs preliminary analysis of pulp characteristics in previous process steps (cooking, delignification, bleaching) to calculate a drying predictive index before the pulp enters the drying step. This advance prediction allows optimization of drying parameters including web speed selection, preventing web breaks before they occur by adjusting speed based on predicted pulp properties

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The web speed is made dynamic and adaptive rather than fixed. The system continuously calculates drying predictive indices and adjusts web speed in real-time based on actual pulp characteristics measured in previous steps, allowing the drying line to optimize speed for each pulp batch to maximize throughput while maintaining reliability

Inventive Principle:

Principle #15Dynamics

2Reliability

If drying parameters are optimized to prevent web breaks, then reliability is improved, but the complexity of the drying control system increases

Engineering Contradiction:

Improveweb break preventionVSAvoiddrying control system complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The system implements a feedback loop where process parameters from previous steps are continuously measured, the drying predictive index is calculated based on this data, and drying parameters are adjusted accordingly. This closed-loop control automates the optimization process, preventing web breaks through systematic feedback rather than complex manual control

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The drying predictive index serves as an intermediary parameter that simplifies control. Instead of directly controlling multiple drying parameters based on complex pulp characteristics, the system uses the calculated index as a mediator to determine optimal drying settings, reducing control complexity while maintaining reliability

Inventive Principle:

Principle #24Intermediary (Mediator)

Data Source

PatentUS20230407567A1Method of controlling the drying of cellulose pulp in a drying step of a pulp production process

Publication Date: 2023.12.21 ANDRITZ TECH & ASSET MANAGEMENT GMBH

AI summary

A method of controlling the drying of cellulose pulp in a drying step of a pulp production process. The method including measuring a plurality of process parameters in at least one previous process step; calculating, based on said process parameters, a drying predictive index indicative of the characteristic of a portion of cellulose pulp processed in said previous process step; determining, based on said drying predictive index, at least one drying parameter for drying of said portion of cellulose pulp; and controlling the drying of said portion of cellulose pulp using said drying parameter.