Hydrogen Recycle Integration for Compact Reforming Plants
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Solution Overview
Problem
Existing methods for producing hydrogen require significant expansion and cost of downstream plant components due to the inert nature of hydrogen in PSA residual gas, leading to inefficient and costly hydrogen production.
Innovation Solution
The recycled gas containing hydrogen and hydrocarbons is combined with fresh feedstock upstream of the reforming step, allowing for hydrogen separation before reforming, reducing the load on downstream processes and enabling more compact, cost-effective equipment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If PSA residual gas containing hydrogen and carbon compounds is compressed and recycled directly to the reforming step, then carbon compounds are converted to carbon dioxide and hydrogen yield increases, but the reforming process and downstream plant components must be enlarged much more significantly at considerable expense
Solution Approach 1:
The patent segments the recycled gas stream into two separate streams: one containing carbon compounds (CO, CO2, hydrocarbons) and another containing inert hydrogen. The carbon compound stream is recycled to the reforming step while the hydrogen-rich stream is separated and reused upstream. This segmentation allows the reforming process to handle only the necessary carbon-containing gases without being oversized by the large volume of inert hydrogen, thus resolving the contradiction between increasing hydrogen yield through recycling and avoiding excessive plant enlargement.
Solution Approach 2:
The patent extracts inert hydrogen from the PSA residual gas before recycling the remaining carbon compound-containing gas to the reforming step. By taking out the inert hydrogen component, the recycled gas stream becomes more concentrated in carbon compounds, improving reforming efficiency without requiring significant enlargement of the reforming process and downstream equipment. This extraction resolves the technical contradiction by enabling carbon compound conversion while avoiding the penalty of processing excessive inert gas volume.
2Device complexity
If hydrogen is separated from the first component mixture before reforming, then the load on downstream processes is reduced and equipment can be more compact, but additional separation equipment is required
Solution Approach 1:
The patent performs preliminary separation of hydrogen from the recycled gas stream before the reforming step. By conducting this separation action in advance, the subsequent reforming process and downstream equipment only need to handle the carbon compound-containing gas, allowing for more compact equipment sizing. The preliminary action of hydrogen separation, though requiring additional equipment, enables significant reduction in the size of downstream processes, resolving the contradiction between equipment compactness and process complexity.
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 enhances hydrogen yield and reduces the need for additional compression, resulting in a more economical and efficient hydrogen production process.
Implementation Method 1
the hydrogen-rich synthesis gas is typically treated by pressure swing adsorption (PSA), whereby the carbon compounds, along with some of the hydrogen, are converted into a residual PSA gas
Implementation Method 2
hydrocarbon-containing feedstocks can be reformed to a raw synthesis gas, for example, by steam reforming, partial oxidation, autothermal reforming
Implementation Method 3
The reforming step is followed by catalytic carbon monoxide conversion (CO shift), which produces a hydrogen-rich synthesis gas containing carbon dioxide
Data Source
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AI summary
The invention relates to a method and a plant (100, 200) for obtaining a hydrogen product (P), in which hydrogen (102) is separated from a first component mixture (A) containing hydrogen and at least one hydrocarbon in order to form a second component mixture (B) which is depleted in hydrogen compared to the first (A), which is subjected to a reforming step (4) in order to produce a third component mixture (C) which has a higher hydrogen and a lower hydrocarbon content than the second component mixture (B), and from which a residual gas (D) containing hydrogen and at least one hydrocarbon is separated while retaining at least a part (113) of the hydrogen product (P) in order to process it into a recycled gas (R) containing hydrogen and at least one hydrocarbon.The characteristic feature here is that the recycled gas (R) containing hydrogen and at least one hydrocarbon is combined with a fresh feedstock (F) comprising hydrogen and at least one hydrocarbon to form the first component mixture (A).