Active-Redundant Drive System for Roller Mill Availability

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Solution Overview

Problem

Modern roller mills face significant downtime and inefficiencies during maintenance and repairs due to the need to remove and replace entire drive systems for inspection and replacement, which is time-consuming and costly, and existing multi-motor drive concepts suffer from lower efficiency and reliability issues.

Innovation Solution

An active-redundant drive system with multiple drives ensures continuous operation by distributing the load, allowing for quick replacement of individual components, using high-speed electric motors, and enabling visual inspection without disassembly, with frequency converters for synchronized control and standard asynchronous motors for simplicity.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a single drive system is used, then the structure is simple and cost-effective, but the mill must be shut down for maintenance and repairs

Engineering Contradiction:
ImproveavailabilityVSAvoiddrive system complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The drive system is segmented into multiple independent drives (at least two), each capable of operating separately. This allows one drive to be maintained while another continues operation, resolving the contradiction between reliability and complexity by distributing the drive function across separate units.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The system incorporates redundant drives as a preventive measure before failures occur. When one drive fails or requires maintenance, the redundant drive(s) are already in place to immediately take over, cushioning against downtime and maintaining continuous operation.

Inventive Principle:
Principle #11Beforehand cushioning (Prior cushioning)

2Ease of repair

If entire drive systems are removed for inspection, then complete examination is possible, but maintenance time and costs increase significantly

Engineering Contradiction:
Improveinspection accessibilityVSAvoidmaintenance downtime
Core Design Contradiction:
Ease of repairVSLoss of time

Solution Approach 1:

The drive system is divided into modular units that can be independently accessed and maintained. The mill can operate on remaining drives while specific drive components are inspected or repaired, eliminating the need to shut down the entire system for maintenance.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The system maintains continuous grinding operation through redundant drives. While one drive is undergoing maintenance or inspection, other drives continue to provide grinding capacity, ensuring the useful action of material processing never中断.

Inventive Principle:
Principle #20Continuity of useful action

3Power

If high-power transmissions are used, then the required drive power is achieved, but the motors become large and less dynamic

Engineering Contradiction:
Improvedrive powerVSAvoidmotor response speed
Core Design Contradiction:
PowerVSSpeed

Solution Approach 1:

The total drive power requirement is segmented across multiple drives, each handling a portion of the load. This allows the use of smaller, higher-speed motors with better dynamic response characteristics, while the combined power of multiple motors meets the total power requirement.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

Each individual drive provides partial power output rather than one large drive providing full power. The cumulative effect of multiple partial-power drives achieves the required total power while maintaining the dynamic advantages of smaller, faster-response motor units.

Inventive Principle:
Principle #16Partial or excessive action

Data Source

PatentEP2086685B8Safety system for roller mills
Publication Date: 2012.09.19 GEBR PFEIFFER SE

AI summary

The invention relates to drive systems for roller mills. To ensure the continuous availability of the mill, more than two drives (10, 11) are provided, wherein the at least two drives (10, 11) are capable of achieving the full grinding capacity of the roller mill.