DC Arc Furnace Anode Cap Structure for Thermal Shock Protection

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Solution Overview

Problem

Direct current electric arc furnaces experience premature failure of steel pins and surrounding dry vibratable monolithic refractory material due to thermal shock, leading to incomplete utilization of the anode's life expectancy.

Innovation Solution

An anode design featuring an anode cap positioned on top of the dry vibratable monolithic refractory material, with steel pins extending through pin holes in the cap, and a protective layer of refractory backfill material, providing thermal protection and a uniform sintered zone to extend the lifespan of the anode.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Duration of action of stationary object

If dry vibratable monolithic refractory material is used to surround steel pins, then the anode can operate up to 1500 heats, but the refractory material is highly susceptible to thermal shock failure resulting in only 300 heats before anode replacement

Engineering Contradiction:

Improveanode operational lifeVSAvoidrefractory material reliability

Core Design Contradiction:

Duration of action of stationary objectVSReliability

Solution Approach 1:

The patent applies beforehand cushioning by placing a layer of granular refractory material between the steel pins and the dry vibratable monolithic refractory material. This granular layer acts as a cushion that absorbs and distributes thermal shock stresses before they reach the brittle monolithic refractory, preventing catastrophic failure and extending anode operational life from 300 to 1500 heats.

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

Solution Approach 2:

The patent creates a composite refractory structure combining two different refractory materials: granular refractory material providing shock absorption and monolithic refractory material providing structural integrity. This composite approach leverages the complementary strengths of both materials to simultaneously improve reliability and duration of action.

Inventive Principle:

Principle #40Composite materials

2Reliability

If steel pins are used as return path for electrical flow, then electrical function is achieved, but severe wear of surrounding refractory material occurs due to severe temperatures

Engineering Contradiction:

Improveelectrical return path functionVSAvoidthermal damage to refractory

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The granular refractory material serves as an intermediary layer between the steel pins and the monolithic refractory structure. This intermediary absorbs and distributes the thermal stress and heat generated by the electrical current flow through the steel pins, preventing direct thermal damage to the surrounding refractory materials while maintaining the electrical return path function.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Productivity

If arc is generated between cathode and anode, then melting of charged material is achieved, but severe temperatures result in severe wear of refractory surrounding steel pins

Engineering Contradiction:

Improvemelting capabilityVSAvoidthermal wear of refractory

Core Design Contradiction:

ProductivityVSObject-affected harmful factors

Solution Approach 1:

The granular refractory material is positioned beforehand to cushion and distribute the severe thermal stresses generated by the arc between cathode and anode. This layer prevents concentrated thermal wear on the monolithic refractory surrounding the steel pins, enabling sustained high-temperature operation for productivity while reducing thermal damage.

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

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

The anode cap and protective layer enhance the durability of the anode, preventing thermal shock damage and extending the anode's life by creating a more uniform and predictable protective layer, thereby increasing the furnace's operational cycles before requiring anode replacement.

Implementation Method 1

anode cap positioned on top of the dry vibratable monolithic refractory material serves to protect the dry vibratable from thermal shock damage at the start-up of the furnace

Methodology Applied

Scientific EffectThermal shock resistance: Thermal Shock

Implementation Method 2

allow a hot face surface of the dry vibratable to create a more uniform and predictably generated protective sintered zone below the anode cap

Methodology Applied

Scientific EffectSintering: Sintering

Implementation Method 3

The arc is generated between the graphite top electrode and the anode bottom electrode of the furnace. The arc between the anode and cathode produces severe temperatures in the furnace

Methodology Applied

Scientific EffectElectric arc: Electric Arc

Data Source

PatentUS20250393105A1Anode for direct current electric arc furnace

Publication Date: 2025.12.25 HARBISONWALKER INTERNATIONAL HOLDINGS INC

AI summary

An anode for a direct current electric arc furnace includes dry vibratable monolithic refractory material positioned on a bottom wall of the furnace, a plurality of steel pins extending upward from the bottom wall of the furnace and through the dry vibratable monolithic refractory material, and an anode cap positioned on top of the dry vibratable monolithic refractory material. The steel pins are surrounded by the dry vibratable monolithic refractory material. The anode cap includes a plurality of pin holes formed therein with which the steel pins correspond and through which the steel pins extend.