Hydrogen Generator Combustion Air Control for Stable Start-Up
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Solution Overview
Problem
Conventional fuel cell systems experience unstable combustion in the combustor during start-up, leading to flame extinguishment and increased carbon monoxide production due to rapid expansion of reforming water vapor and increased flow rates of combustible gases, causing air supply deficiencies.
Innovation Solution
A hydrogen generator with a controller that adjusts the air supply to the combustor in conjunction with the introduction of reforming water or air to the reformer or shift converter, ensuring sufficient air is provided to maintain stable combustion by increasing the air supply proportionally with the increase in combustible gas flow rates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If reforming water is supplied to the reformer in a start-up state where material gas is combusted to heat the hydrogen generator, then the reforming water evaporates and increases volume up to 1200 times, but this causes flame extinguishment or imperfect combustion in the combustor
Solution Approach 1:
The control device increases the air supply amount to the combustor before reforming water is supplied to the reformer. This preliminary action ensures that when the reforming water evaporates and causes a sudden increase in gas flow rate, sufficient air is already available to maintain stable combustion and prevent flame extinguishment or imperfect combustion.
2Power
If the flow rate of combustible gas containing material gas is increased in the combustor, then the heating efficiency improves, but the air supply becomes deficient causing unstable combustion
Solution Approach 1:
The air supply amount to the combustor is made variable and is dynamically adjusted based on the gas flow rate conditions. When the flow rate of combustible gas increases, the control device increases the air supply amount proportionally, maintaining the appropriate air-fuel ratio and ensuring stable combustion while preserving heating efficiency.
3Temperature
If air is supplied to the shift converter or purifier during start-up, then the hydrogen-containing gas reacts with air to generate reaction heat, but this increases the flow rate of combustible gas causing back pressure increase and air supply deficiency in the combustor
Solution Approach 1:
When air is supplied to the shift converter or purifier during start-up, the control device preliminarily increases the air supply amount to the combustor in anticipation of the increased back pressure. This ensures that the combustor continues to receive sufficient air despite the back pressure increase caused by air supply to other components.
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 configuration stabilizes combustion, preventing flame extinguishment and reducing carbon monoxide production in the exhaust gas by ensuring adequate air supply during start-up and operation, thereby maintaining efficient power generation.
Implementation Method 1
a combustor for heating the reactor with combustion heat
Implementation Method 2
a reformer which generates a hydrogen-containing gas from a material gas; a reactor filled with a reforming catalyst for catalyzing a steam reforming reaction
Implementation Method 3
a shift converter and a purifier to reduce a carbon monoxide concentration in a hydrogen-containing gas
Implementation Method 4
a shift converter and a purifier to reduce a carbon monoxide concentration in a hydrogen-containing gas
Data Source
AI summary
A hydrogen generator comprises a reformer which generates a hydrogen-containing gas from a steam and a material gas, a first gas supply device which supplies the material gas, a combustor which combusts an exhaust gas exhausted from the reformer to heat the reformer, a combustion air supply device which supplies air to the combustor, a second gas supply device which supplies another gas different from the material gas to the reformer or to a passage connecting the reformer to the combustor, and a controller. The controller is configured to control the combustion air supply device to increase an amount of the air supplied to the combustor (S103), in association with start of supply of the another gas from the second gas supply device (S104), in a state where the material gas is supplied from the first gas supply device to the reformer and the exhaust gas is combusted in the combustor (S101).