Hydrogen Production Process Segmentation for Yield Optimization
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Solution Overview
Problem
Conventional steam reforming processes for hydrogen production from hydrogen-containing input gases result in hydrogen losses and elevated energy usage, as hydrogen is passed through multiple stages alongside hydrocarbons, leading to inefficient hydrogen yield and increased carbon dioxide emissions.
Innovation Solution
A process that separates the input gas stream into hydrogen-enriched and hydrogen-depleted substreams, where the hydrogen-enriched stream is directly fed to a pressure swing adsorption stage for pure hydrogen production, and the hydrogen-depleted stream is used as a reforming feed or fuel gas, optimizing energy efficiency and reducing hydrogen loss.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If hydrogen-containing input gas is passed through multiple steam reforming stages, then complete conversion of hydrocarbons is achieved, but hydrogen losses increase and energy consumption rises
Solution Approach 1:
The input gas stream is divided into two separate substreams: a hydrogen-enriched substream that bypasses the steam reforming stages and goes directly to the PSA unit, and a hydrogen-depleted substream that undergoes steam reforming. This segmentation prevents the hydrogen already present in the input gas from being subjected to multiple reforming and cooling cycles, thereby reducing energy consumption while maintaining complete conversion of hydrocarbons.
Solution Approach 2:
The hydrogen-enriched substream is extracted from the main input gas stream before entering the steam reforming process. This extracted portion is directed straight to the PSA purification unit, removing it from the energy-intensive reforming and cooling cycles. This extraction strategy minimizes hydrogen losses and reduces the overall energy burden of the process.
2Productivity
If hydrogen-containing input gas is passed through multiple steam reforming stages, then complete conversion of hydrocarbons is achieved, but hydrogen losses increase
Solution Approach 1:
The input gas stream is divided into two separate substreams: a hydrogen-enriched substream that bypasses the steam reforming stages and goes directly to the PSA unit, and a hydrogen-depleted substream that undergoes steam reforming. This segmentation prevents the hydrogen already present in the input gas from being subjected to multiple reforming and cooling cycles, thereby reducing hydrogen losses through condensation and carryover.
Solution Approach 2:
The hydrogen-enriched substream is extracted from the main input gas stream before entering the steam reforming process. This extracted portion is directed straight to the PSA purification unit, removing it from the energy-intensive reforming and cooling cycles where hydrogen losses typically occur. This extraction strategy minimizes hydrogen losses and reduces the overall energy burden of the process.
3Stability of the object's composition
If hydrogen-enriched substream is mixed with reforming feed stream, then uniform reformer operation is achieved, but hydrogen yield decreases
Solution Approach 1:
The process maintains separate pathways for the hydrogen-enriched substream (to PSA) and the reforming feed stream (to reformer), preventing mixing that would reduce hydrogen yield. The hydrogen-depleted substream from reforming is then mixed with fresh reforming feed to ensure uniform composition entering the reformer, achieving operational stability without compromising overall hydrogen production.
Solution Approach 2:
The hydrogen-enriched substream is separated and recovered directly for purification rather than being mixed back into the reforming feed. This recovery strategy preserves the hydrogen content for maximum yield, while the hydrogen-depleted substream is recycled to maintain uniform reformer operation.
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 increases the yield of pure hydrogen, reduces energy consumption, and minimizes hydrogen loss, while ensuring uniform reformer operation and reducing carbon dioxide emissions.
Implementation Method 1
the first hydrogen enrichment stage contains a hydrogen-selective membrane, wherein the substream enriched in hydrogen is obtained as permeate stream and the substream depleted in hydrogen is obtained as retentate stream
Implementation Method 2
the second hydrogen enrichment stage is supplied with the reforming product stream and the substream enriched in hydrogen from the first hydrogen enrichment stage, wherein these material streams are mixed before supply or each supplied separately to the second hydrogen enrichment stage
Implementation Method 3
Steam reforming of hydrocarbons is highly endothermic. It is therefore performed in a reformer furnace
Implementation Method 4
The reformer tubes are usually fired with burners mounted on the top or bottom or on the side walls in the interior of the reformer furnace and directly heat the interspace between the reformer tubes
Data Source
AI summary
The invention relates to a process and a plant for producing pure hydrogen from an input gas containing hydrogen and hydrocarbons, in particular from a hydrogen-containing refinery off-gas, by steam reforming in a steam reforming stage and multi-stage hydrogen enrichment. According to the invention the input gas containing hydrogen and hydrocarbons is separated in a first hydrogen enrichment stage into a hydrogen-enriched substream and a hydrogen-depleted substream, wherein at least a portion of the hydrogen-enriched substream is supplied to a second hydrogen enrichment stage or introduced into the pure hydrogen product stream and at least a portion of the hydrogen-depleted substream is supplied to the steam reforming stage as a reforming feed stream or as part thereof and/or to the burners as a fuel gas stream.