Carbon-to-Liquids Reactor H2/CO Ratio Control
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Solution Overview
Problem
Existing carbon-to-liquids systems face challenges in minimizing liquid product variation, particularly in Fischer-Tropsch units, where high residence times and hydrogen to carbon monoxide ratios lead to undesirable wax production and catalyst deactivation, increasing transportation costs and reducing syngas conversion efficiency.
Innovation Solution
The method involves shifting syngas to increase the hydrogen to carbon monoxide ratio, adding additional hydrogen, reacting the mixture with a catalyst, and recycling hydrogen to maintain an optimal H2/CO ratio, thereby reducing catalyst deactivation and minimizing wax production.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If high per pass conversion is used to increase C5+ production, then C5+ selectivity is improved, but water partial pressure increases causing catalyst deactivation
Solution Approach 1:
The patent applies preliminary action by adjusting the H2/CO ratio to stoichiometric proportions before the Fischer-Tropsch reaction occurs. This pre-adjustment prevents excessive water formation during reaction, thereby preventing catalyst deactivation before it can occur. The syngas composition is optimized in advance to match the consumption ratio required by the catalyst, eliminating the need to operate with high per pass conversion that would generate harmful water partial pressures.
Solution Approach 2:
The patent changes the critical parameter of H2/CO ratio from sub-stoichiometric to stoichiometric proportions. This parameter change fundamentally alters the reaction conditions, allowing for lower per pass conversion operation that maintains catalyst stability while still achieving acceptable C5+ production. The systematic adjustment of syngas composition parameters enables operation in a previously inaccessible regime that balances productivity and catalyst reliability.
2Productivity
If high per pass conversion is used to increase C5+ production, then C5+ selectivity is improved, but reactor volume can be reduced
Solution Approach 1:
The patent changes the H2/CO ratio parameter to stoichiometric proportions, which fundamentally alters the conversion characteristics. This parameter change enables operation at lower per pass conversion with extended residence times, producing the unexpected benefit of reduced reactor volume. The optimized syngas composition allows for more efficient utilization of reactor space, achieving C5+ production targets with a smaller reactor footprint than conventional high conversion designs.
3Productivity
If H2/CO ratio is maintained at stoichiometric proportions, then syngas conversion efficiency is improved, but additional hydrogen addition and recycling equipment is required
Solution Approach 1:
The patent implements feedback control through hydrogen recycling. Unreacted hydrogen is extracted from the product stream and fed back to the reactor inlet, creating a closed-loop system that maintains stoichiometric H2/CO proportions. This feedback mechanism ensures continuous optimization of syngas conversion efficiency, automatically adjusting the effective H2/CO ratio at the reactor inlet based on actual consumption in the catalyst bed.
Solution Approach 2:
The patent applies discarding and recovering by extracting unreacted hydrogen from the product stream and recovering it for reuse. Instead of discarding the hydrogen in the unreacted syngas, the system recovers it through separation equipment and feeds it back to the reactor, improving overall conversion efficiency while maintaining stoichiometric proportions throughout the 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 allows for a smaller reactor volume, higher per pass conversion, and increased hydrocarbon purity, reducing product variation and operational costs while maintaining a stoichiometric H2/CO ratio, even at the reactor outlet.
Implementation Method 1
shifting the syngas to facilitate increasing a hydrogen to carbon monoxide ratio (H2/CO) of the syngas
Implementation Method 2
reacting the hydrogen/shifted syngas mixture with a catalyst in a vessel
Implementation Method 3
a catalyst configured to facilitate a Fischer-Tropsch synthesis reaction
Implementation Method 4
extracting hydrogen from the syngas mixture
Data Source
AI summary
A method of operating a carbon-to-liquids system is provided. The method includes receiving a flow of syngas at the carbon-to-liquids system, shifting the syngas to facilitate increasing a hydrogen to carbon monoxide ratio (H2/CO) of the syngas, adding additional hydrogen to the shifted syngas to increase the H2/CO ratio, reacting the hydrogen/shifted syngas mixture with a catalyst in a vessel, extracting hydrogen from the syngas mixture, recycling the hydrogen to facilitate increasing the H2/CO ratio, and recycling naphta to act as solvent for wax extraction, and to facilitate catalyst recovery.