Hydrogen Generator Catalyst Protection During Shutdown
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Solution Overview
Problem
Hydrogen generators face the challenge of reforming catalyst degradation due to steam oxidation during shut-down operations, particularly when air enters the system, leading to oxidization of the catalyst, which is not effectively addressed by existing methods.
Innovation Solution
A method for operating a hydrogen generator that involves controlling the supply of material gas to the reformer during the shut-down process, specifically by supplying the material gas after the gas has become incombustible and during the evaporation of residual water, thereby reducing the steam concentration and preventing steam oxidation of the catalyst.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the hydrogen generator is shut down by stopping material gas and water supply, then the power generation system can respond to electric load changes efficiently, but steam condensation and temperature decrease cause negative pressure that allows air to flow into the generator and oxidize the catalyst
Solution Approach 1:
The patent applies preliminary action by supplying inert gas to the reformer before and during the shut-down process. This preemptive measure displaces steam and prevents air ingress before oxidation can occur, protecting the catalyst during the transition to shut-down state.
Solution Approach 2:
The patent creates an inert atmosphere within the reformer by introducing inert gas (such as nitrogen or carbon dioxide) during shut-down. This inert environment prevents oxygen from contacting the catalyst, thereby preventing oxidation while allowing the system to respond to load changes efficiently.
2Object-affected harmful factors
If the reforming reaction unit is sealed after stopping material gas and water supply, then air penetration is prevented, but inner pressure rises due to steam from residual water and depressurization creates a steam atmosphere that oxidizes the catalyst
Solution Approach 1:
The patent introduces inert gas into the sealed reformer to displace the steam atmosphere. This creates an inert environment that prevents oxidation of the catalyst while maintaining the sealed condition necessary to prevent air penetration.
Solution Approach 2:
The patent changes the atmospheric composition parameter within the reformer by introducing inert gas. This parameter change transforms the oxidizing steam atmosphere into a protective inert atmosphere, preventing catalyst oxidation during the depressurization phase.
3Ease of operation
If the reforming reaction unit is kept open to the atmosphere after stopping material gas and water supply, then depressurization is simplified, but residual water evaporation creates a steam atmosphere that oxidizes the catalyst
Solution Approach 1:
The patent introduces inert gas to displace the steam atmosphere even when the reformer remains open to the atmosphere. This creates a local inert environment around the catalyst that prevents oxidation while maintaining operational simplicity.
Solution Approach 2:
The patent maintains continuous protection of the catalyst by sustaining the inert gas supply throughout the period when residual water is evaporating. This continuous action ensures the catalyst remains protected despite the simplified open depressurization process.
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 significantly reduces the possibility of steam oxidation of the reforming catalyst, compared to conventional methods, by maintaining a lower steam concentration and preventing catalyst degradation.
Implementation Method 1
a reforming catalyst and generates hydrogen-containing gas by a reforming reaction between steam and material gas
Implementation Method 2
during the evaporation of residual water
Implementation Method 3
supplying the material gas to the reformer... reducing the steam concentration
Data Source
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AI summary
The invention discloses a hydrogen generator (100A) comprising: a reformer (1) having a reforming catalyst (1a); a material gas supply device (13); an evaporator (3); a water supply device; and a controller (10) which controls the material gas supply device (13) and the water supply device to stop supplying of a material gas to the reformer (1) and supplying of water to the evaporator (3) and then controls the material gas supply device (13) to supply the material gas to the reformer (1) in a period during which residual water evaporates in at least either the evaporator (3) or the reformer (1).