Fischer-Tropsch Reactor Inert Removal via PSA
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Solution Overview
Problem
In remote natural gas processing sites, existing technologies face challenges in efficiently converting hydrocarbons to valuable synthetic fuels due to limited space and self-sufficiency requirements, with issues related to inert component buildup and diffusion resistance in multi-stage Fischer-Tropsch reactors, which affect hydrocarbon yield and catalyst productivity.
Innovation Solution
An integrated system is developed that includes a CO2 removal step in the synthesis gas feed to the Fischer-Tropsch reactor system, optimizing the H2 to CO ratio and partial pressure of synthesis gas, using a multi-bed pressure swing adsorption unit to enhance hydrogen addition, and compressing waste gas to maintain optimal reactor conditions, thereby reducing inert component concentration and increasing hydrocarbon conversion efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If multi-stage Fischer-Tropsch reactors are used to convert synthesis gas to hydrocarbons, then hydrocarbon yield is improved, but inert component buildup and diffusion resistance increase, reducing catalyst productivity
Solution Approach 1:
The patent extracts and removes inert components (CO2 and other impurities) from the synthesis gas stream between reactor stages using adsorption beds and separation units. This prevents inert buildup in the multi-stage reactor system while maintaining high hydrocarbon yield, directly resolving the contradiction between productivity and harmful factor accumulation
Solution Approach 2:
The patent implements preliminary cleaning of synthesis gas feedstock before it enters the multi-stage Fischer-Tropsch reactors by removing CO2 and inert components upfront. This preliminary action prevents diffusion resistance and catalyst deactivation before they occur, maintaining high catalyst productivity throughout the reaction stages
2Duration of action of stationary object
If CO2 is present in synthesis gas feed to Fischer-Tropsch reactor, then catalyst life is extended, but hydrocarbon conversion efficiency and C5+ selectivity decrease
Solution Approach 1:
The patent carefully controls and optimizes the CO2 concentration parameter in the synthesis gas feed, maintaining it within a specific range (0.1-10% by volume) that balances catalyst life extension with acceptable hydrocarbon conversion efficiency. This parameter optimization resolves the contradiction by finding the optimal operating point
Solution Approach 2:
The patent applies partial removal of CO2 rather than complete elimination, maintaining a small controlled amount of CO2 in the synthesis gas feed. This partial action extends catalyst life while minimizing the negative impact on conversion efficiency, resolving the contradiction through controlled compromise
3Productivity
If H2 to CO ratio in synthesis gas is increased to improve C5+ hydrocarbon selectivity, then conversion efficiency improves, but more hydrogen is consumed and carbon monoxide availability decreases
Solution Approach 1:
The patent implements feedback control of the H2 to CO ratio in the synthesis gas feed to the Fischer-Tropsch reactor. By monitoring the ratio and adjusting hydrogen addition or synthesis gas composition accordingly, the system optimizes C5+ selectivity while managing hydrogen consumption levels, resolving the contradiction through dynamic balance
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 increases the yield of hydrocarbons with carbon numbers greater than 5, particularly C12+, by optimizing catalyst productivity and selectivity, while minimizing the carbon footprint and operational costs, and allows for efficient recycling of gases, reducing the need for further compression and inert component buildup.
Implementation Method 1
using a multi-bed pressure swing adsorption unit to enhance hydrogen addition
Implementation Method 2
Fischer-Tropsch catalytic hydrocarbon synthesis system
Implementation Method 3
integrated with a gas turbine which provides at least part of the energy required
Data Source
AI summary
An integrated plant for the conversion of a hydrocarbon gas such as natural gas to useful hydrocarbon liquid fuels and feed-stocks comprises an H2+CO syn-gas generation system which provides feed gas to a Fischer-Tropsch catalytic hydrocarbon synthesis system with an associated power and heat energy system.