Method for producing hydrogen and methanol
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Solution Overview
Problem
Existing methods for co-producing hydrogen and methanol face inefficiencies due to excess hydrogen purge gas containing valuable carbon oxides, which are not utilized effectively, leading to economic losses and suboptimal methanol production.
Innovation Solution
A method that involves reforming hydrocarbons to produce synthesis gas, followed by a water gas shift reaction to adjust the hydrogen-carbon oxide ratio, cooling, and then dividing the gas stream for separate hydrogen and methanol production, with recycled off-gases to minimize waste and optimize stoichiometric composition.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If excess hydrogen is purged from the methanol synthesis loop to remove inert components, then the methanol synthesis reactor operates with optimal composition, but valuable carbon oxides are lost and hydrogen production efficiency decreases
Solution Approach 1:
The synthesis gas stream is divided into multiple streams with different destinations: one stream is purged to remove inerts from the methanol loop, while another stream is directed to a hydrogen separation device to recover hydrogen and carbon oxides that would otherwise be wasted. This segmentation allows selective removal of harmful components while preserving valuable materials.
Solution Approach 2:
Instead of simply discarding the purge gas containing valuable carbon oxides and hydrogen, the invention recovers these components by directing the purge stream to a hydrogen separation device. The separated hydrogen and carbon oxides are then recycled back to the methanol synthesis reactor, converting waste into useful feedstock.
2Device complexity
If a single synthesis gas stream is used for both hydrogen and methanol production, then process integration is simplified, but the stoichiometric composition cannot be optimized for both products simultaneously
Solution Approach 1:
The synthesis gas stream is segmented into multiple branches after the water-gas shift reactor. One branch is directed to the hydrogen separation device for hydrogen production, while another branch is directed to the methanol synthesis reactor. This segmentation allows each product stream to be optimized independently for its specific stoichiometric requirements.
Solution Approach 2:
The invention changes the flow distribution parameters of the synthesis gas stream to different branches based on production demands. By adjusting the split ratio and recycling rates, the system optimizes the hydrogen-carbon oxide ratio for hydrogen production in one branch while maintaining the appropriate ratio for methanol synthesis in another branch.
3Stability of the object's composition
If the synthesis gas is cooled and condensed before division, then the gas composition is stabilized, but the energy required for subsequent heating is increased
Solution Approach 1:
The synthesis gas is cooled and condensed before being divided into different streams. This preliminary cooling stabilizes the gas composition and removes excess water, creating a more consistent feedstock for both hydrogen and methanol production. The energy cost of subsequent reheating is offset by the benefits of composition stabilization and water removal.
Solution Approach 2:
The cooling and condensation steps are combined into a single integrated unit that performs both functions. The condensed water is removed, and the cooled gas is then divided into branches. This combined approach reduces overall energy consumption compared to separate cooling and condensation units, as the condensed water removal prevents re-evaporation and energy loss.
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 the co-production efficiency of hydrogen and methanol by reducing waste and optimizing the use of synthesis gas components, thereby improving production economics and process integration.
Implementation Method 1
introducing the syngas stream to a water gas shift reaction thereby converting at least a portion of the CO and H2O into H2 and CO2
Implementation Method 2
cooling the shifted gas stream and condensing and removing the condensed fraction of H2O
Implementation Method 3
a hydrogen separation device, a pressure swing adsorption unit in Figure 1, may be used to separate the hydrogen for export
Implementation Method 4
The synthesis gas may be produced in a steam reformer, an autothermal reformer, or a partial oxidation reformer
Implementation Method 5
The synthesis gas may be produced in a steam reformer, an autothermal reformer, or a partial oxidation reformer
Implementation Method 6
The synthesis gas may be produced in a steam reformer, an autothermal reformer, or a partial oxidation reformer
Implementation Method 7
Methanol is produced by reacting the synthesis gas catalytically in a pressurized reactor to yield methanol
Data Source
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AI summary
A method for the co-production of hydrogen and methanol including a hydrocarbon reforming or gasification device producing a syngas stream comprising hydrogen, carbon monoxide and carbon dioxide; introducing the syngas stream to a water gas shift reaction thereby converting at least a portion of the CO and H2O into H2 and CO2 contained in a shifted gas stream; cooling the shifted gas stream and condensing and removing the condensed fraction of H2O; then dividing the shifted syngas stream into a first stream and a second stream; introducing the first stream into a first hydrogen separation device, thereby producing a hydrogen stream, and introducing the second stream into a methanol synthesis reactor, thereby producing a crude methanol stream and a methanol synthesis off gas; introducing at least a portion of the methanol synthesis off gas into a second hydrogen separation device.