Oxidation Oven Cleaning via High-Pressure Liquid and Gas Circulation

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Solution Overview

Problem

Conventional oxidation ovens face challenges in maintaining continuous operation due to dust accumulation, which leads to quality deterioration of carbon fibers and increased maintenance costs, as existing cleaning methods are inefficient and require frequent manual intervention.

Innovation Solution

A method involving a mechanism to circulate an oxidizing gas with a temperature of 40°C or higher and applying a liquid with a pressure of 2 MPa or more to dislodge dust from the oven walls, followed by gas circulation and directional changes to effectively remove adhering dust without significant thermal energy loss.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Loss of energy

If a hot air circulation system is used to reduce thermal energy loss, then energy efficiency is improved, but dust accumulates in the oxidation oven and adheres to the precursor fiber

Engineering Contradiction:
Improvethermal energy lossVSAvoiddust accumulation
Core Design Contradiction:
Loss of energyVSObject-affected harmful factors

Solution Approach 1:

The invention extracts and removes dust from the hot air circulation system by introducing a dust removal device that separates dust particles from the circulating hot air, allowing the hot air to continue circulating while dust is extracted and discharged, thus resolving the contradiction between energy efficiency and dust accumulation

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The invention introduces a dust removal device as an intermediary component between the hot air circulation system and the oxidation oven chamber, which mediates the conflict by filtering dust from the hot air without disrupting the thermal circulation, thereby maintaining energy efficiency while preventing dust accumulation

Inventive Principle:
Principle #24Intermediary (Mediator)

2Reliability

If dust accumulates in the oxidation oven, then cleaning frequency must increase, but this reduces productivity and increases maintenance costs

Engineering Contradiction:
Improvecarbon fiber qualityVSAvoidproduction efficiency
Core Design Contradiction:
ReliabilityVSProductivity

Solution Approach 1:

The invention performs preliminary dust removal by continuously or periodically removing dust from the hot air circulation system before dust can accumulate and adhere to the precursor fiber, thereby maintaining carbon fiber quality without requiring frequent production stoppages for cleaning

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The invention maintains continuous dust removal operation alongside the continuous hot air circulation, ensuring that dust is constantly removed without interrupting the oxidation process, thereby maintaining both quality and productivity

Inventive Principle:
Principle #20Continuity of useful action

3Object-affected harmful factors

If manual cleaning is performed frequently, then dust accumulation is reduced, but downtime increases and maintenance costs rise

Engineering Contradiction:
Improvedust accumulationVSAvoiddowntime
Core Design Contradiction:
Object-affected harmful factorsVSLoss of time

Solution Approach 1:

The invention implements self-service dust removal by equipping the hot air circulation system with an integrated dust removal device that automatically removes dust during operation, eliminating the need for manual cleaning interventions and associated downtime

Inventive Principle:
Principle #25Self-service

Solution Approach 2:

The invention replaces manual mechanical cleaning with an automated dust removal mechanism that uses the existing hot air circulation flow to transport and remove dust, substituting human labor with an automated system that operates continuously without downtime

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

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 method enables stable, high-quality production of oxidized fibers by reducing downtime and maintenance costs, allowing for long-term continuous operation of the oxidation oven with improved dust removal efficiency.

Implementation Method 1

causing a liquid to come in contact with dust adhering to a wall surface of the oxidation oven so that pressure in a direction perpendicular to the wall surface is 2 MPa or more

Methodology Applied
Scientific EffectPressure: Pressure Increase

Implementation Method 2

circulating an oxidizing gas having a temperature of 40°C or higher in the oxidation oven

Methodology Applied
Scientific EffectGas circulation: Convection

Implementation Method 3

circulating an oxidizing gas having a temperature of 40°C or higher in the oxidation oven

Methodology Applied
Scientific EffectThermal heating: Heating

Data Source

PatentEP3540101B1Method for cleaning flameproofing furnace, method for manufacturing flameproof fiber, carbon fiber, and graphitized fiber
Publication Date: 2020.08.26 TORAY INDUSTRIES INC
  • EP3540101B1 patent drawingFigure 1
  • EP3540101B1 patent drawingFigure 2
  • EP3540101B1 patent drawingFigure 3

AI summary

[PROBLEMS] It is to provide a method for cleaning an oxidation oven, which can obtain a high-quality carbon fiber immediately after re-operating the oxidation oven, can easily clean the inside of the oxidation oven, and can reduce a period in which production is stopped, a method for producing an oxidized fiber and a method for producing a carbon fiber including the step of cleaning the oxidation oven using the cleaning method. [SOLUTIONS] A method for cleaning an oxidation oven for subjecting a polyacrylonitrile-based precursor fiber for carbon fiber to an oxidation treatment in an oxidizing atmosphere, wherein: the oxidation oven has a mechanism for circulating an oxidizing gas internally; and the method comprising the steps of: causing a liquid to come in contact with dust adhering to a wall surface of the oxidation oven so that pressure in a direction perpendicular to the wall surface is 2 MPa or more; discharging the liquid out of the oxidation oven to discharge the dust peeled off from the wall surface out of the oxidation oven; and circulating an oxidizing gas having a temperature of 40°C or higher in the oxidation oven.