Anode Baking Furnace Gas Flow Control for Stable Degassing Front

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Solution Overview

Problem

Existing ring furnace control processes struggle to maintain a stable degassing front position, leading to safety hazards and inefficiencies, especially in furnaces with long cycles or those sensitive to smoke formation from unburnt residues, as they require a balance between sufficient air flow for complete combustion and preventing unburnt combustible volatile matter from igniting.

Innovation Solution

The control process divides the natural pre-heating zone into two sections, allowing independent control of gas flow and temperature in the first zone, enabling precise regulation of the degassing front by modifying gas flows between these zones, including the introduction of outside air to cool gases before they enter the first pre-heating zone, thereby optimizing combustion and preventing cold degassing.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Use of energy by moving object

If gas flow rate is increased to ensure complete combustion of fuels, then combustion efficiency is improved, but the degassing front moves closer to suction ramps creating safety hazards

Engineering Contradiction:

Improvecombustion efficiencyVSAvoidsafety of degassing front position

Core Design Contradiction:

Use of energy by moving objectVSReliability

Solution Approach 1:

The natural pre-heating zone is divided into two separate zones: a first zone where the degassing front is controlled to remain at a safe distance from suction ramps, and a second zone where gas flow rate is increased to ensure complete combustion. This segmentation allows each zone to have optimized gas flow rates for its specific function, resolving the contradiction between safety and combustion efficiency.

Inventive Principle:

Principle #1Segmentation

2Reliability

If gas flow rate is decreased to maintain degassing front at safe distance, then safety is improved, but combustion of fuels becomes incomplete leading to smoke formation

Engineering Contradiction:

Improvesafety of degassing front positionVSAvoidsmoke from unburnt residues

Core Design Contradiction:

ReliabilityVSObject-generated harmful factors

Solution Approach 1:

By dividing the pre-heating zone into two sections with different gas flow rates, the system achieves complete combustion in the second zone without compromising the safety margin in the first zone. The first zone maintains lower gas flow to keep the degassing front at a safe distance, while the second zone uses higher gas flow to ensure complete combustion and prevent smoke formation.

Inventive Principle:

Principle #1Segmentation

3Device complexity

If single-zone pre-heating control is used, then device complexity is reduced, but ability to independently control degassing front position and combustion conditions is insufficient

Engineering Contradiction:

Improvecontrol system structureVSAvoidindependent control capability

Core Design Contradiction:

Device complexityVSAdaptability or versatility

Solution Approach 1:

The control system is segmented into two independent control zones, each with its own gas flow rate control. This allows the degassing front position to be controlled independently from the combustion conditions, providing the adaptability needed to optimize both safety and combustion efficiency without significantly increasing overall system complexity.

Inventive Principle:

Principle #1Segmentation

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 allows for flexible operation across various cycle times, ensures complete combustion of fuels, prevents smoke from unburnt residues, and maintains a safe distance of the degassing front from suction ramps, enhancing energy efficiency and reducing the risk of furnace damage.

Implementation Method 1

modifying gas flows between these zones, including the introduction of outside air to cool gases before they enter the first pre-heating zone

Methodology Applied

Scientific EffectHeat exchange: Heat Exchanger

Implementation Method 2

during which the anodes release combustible volatile matter which burns inside the hollow partitions forming a degassing front to pre-heat the gases, the partitions and the anodes

Methodology Applied

Scientific EffectCombustion: Combustion

Data Source

PatentUS9958208B2Control process for an anode baking furnace and adapted furnace using such process

Publication Date: 2018.05.01 RIOTINTO ALCAN INT LTD

AI summary

Control process for a furnace for baking carbon anodes comprising:longitudinal hollow partitions in each of which a flow of hot baking gas may circulate, hollow partitions together defining cells to receive the anodes to be baked,and a heating system rotating in relation to the hollow partitions comprising an upstream blowing ramp blowing air into the various partitions, a downstream suction ramp sucking gas from the various partitions and at least one heating ramp.This process comprises a natural pre-heating phase of the partitions and anodes which release combustible, volatile matter which burns inside the hollow partitions as a degassing in a natural pre-heating zone of the furnace downstream of the heating ramp. According to the invention, gas flows circulating in the hollow partitions are modified so as to control gas flows passing through a first natural pre-heating zone from gas flows leaving a second natural pre-heating zone to control the location of the degassing front.