Mineral-Insulated Spark Igniter for SOFC Startup Light-Off

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Solution Overview

Problem

Ceramic glow plugs in fuel cell systems face reliability and longevity issues due to thermal stress, micro-crack formation, and oxidation of brazing, leading to leaks and open circuit conditions, especially in high-temperature environments.

Innovation Solution

A spark igniter using a mineral insulated cable is positioned within the fuel cell system's reaction zone, generating a spark with a high DC voltage to initiate oxidation, reducing the need for high power consumption and minimizing the risk of micro-cracks and oxidation, with the cable's flexibility allowing easy routing without compromising seals.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Temperature

If ceramic glow plugs are used to initiate oxidation in high-temperature environments, then the fuel cell system can achieve startup heating, but thermal stress and micro-crack formation reduce reliability and longevity

Engineering Contradiction:

Improvelight-off temperatureVSAvoidoperational reliability

Core Design Contradiction:

TemperatureVSReliability

Solution Approach 1:

The patent replaces the mechanical heating system (ceramic glow plug) with an electrical discharge system (spark igniter). The spark igniter uses electrical energy to create a high-temperature spark that initiates oxidation without requiring a physically present heating element in the reaction zone, thereby eliminating thermal stress and micro-crack formation associated with ceramic materials.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent introduces an insulated cable as an intermediary to deliver electrical energy to the reaction zone. The cable insulation prevents direct contact between the electrical discharge path and the hotbox interior, allowing the spark to be generated within the reaction zone while protecting the electrical components from high temperatures and corrosive atmosphere.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Temperature

If ceramic glow plugs are used for heating, then startup heating can be achieved, but oxidation of brazing leads to open circuit conditions

Engineering Contradiction:

Improvelight-off temperatureVSAvoidelectrical connectivity

Core Design Contradiction:

TemperatureVSReliability

Solution Approach 1:

The patent replaces the ceramic glow plug system with an electrical spark system that does not rely on brazed joints for structural integrity. The spark igniter uses electrical discharge to generate heat, eliminating the brazing oxidation problem that plagues ceramic heating elements in high-temperature, oxidizing environments.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The spark igniter system uses consumable electrical energy rather than durable ceramic components with finite lifespans. The electrical discharge can be generated on-demand without degrading physical components, effectively making the heating mechanism 'infinite' in duration limited only by the electrical power supply.

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

3Productivity

If high power consumption is used for heating, then rapid heating can be achieved, but the risk of micro-crack formation and oxidation increases

Engineering Contradiction:

Improveheating rateVSAvoidcomponent integrity

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The spark igniter delivers energy in the form of periodic electrical discharges rather than continuous high-power heating. Each spark provides a brief, intense burst of energy sufficient to initiate oxidation, after which the system requires minimal power to sustain the reaction, thereby achieving rapid startup without continuous high-power exposure that would cause thermal stress and component degradation.

Inventive Principle:

Principle #19Periodic action

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 spark igniter effectively initiates oxidation at a light-off temperature with low power consumption, withstands high temperatures, and reduces the risk of micro-crack formation and oxidation, enhancing the operational reliability and longevity of the fuel cell system.

Implementation Method 1

A spark igniter may be used to initiate oxidation rather than a ceramic glow plug. Specifically, a mineral insulated cable configured to generate a spark when a sufficient voltage is applied thereto may be used for this purpose.

Methodology Applied

Scientific EffectElectrical discharge (spark): Electric Spark

Implementation Method 2

A spark igniter using a mineral insulated cable is positioned within the fuel cell system's reaction zone, generating a spark with a high DC voltage

Methodology Applied

Scientific EffectThermal resistance: Thermal Insulation

Data Source

PatentUS11824232B2Internal light off mechanism for solid oxide fuel cell system startup using a spark ignitor

Publication Date: 2023.11.21 BLOOM ENERGY CORP

AI summary

A fuel cell system includes at least one spark igniter containing an insulated cable where at least a first end of the insulated cable is positioned within a reaction zone of the fuel cell system. A power supply is configured to provide a direct current (DC) voltage to the at least one spark igniter such that a spark is generated at the first end of the insulated cable.