Fischer-Tropsch Tail Gas Recycling Without Saturators
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Solution Overview
Problem
Current Fischer-Tropsch processes require expensive saturators and pure oxygen, which are not always readily available, and result in unwanted side reactions and heavy by-products when recycling Fischer-Tropsch tail gas and water.
Innovation Solution
Incorporating a method to superheat Fischer-Tropsch tail gas and inject Fischer-Tropsch water into it to form a mixed gas, which is then recycled as a feed to the syngas preparation unit, maintaining the gas in a vapor phase to avoid corrosion and downstream catalyst issues, and using a water-gas shift reactor to adjust the H2/CO ratio.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If Fischer-Tropsch tail gas and water are recycled using conventional methods with saturators and pure oxygen, then the syngas production can be maintained, but the process cost increases and unwanted side reactions occur producing heavy by-products
Solution Approach 1:
The invention extracts and eliminates the need for saturators and pure oxygen from the conventional Fischer-Tropsch recycling process. By removing these complex components, the process achieves syngas production without the associated high costs and unwanted side reactions that produce heavy by-products
Solution Approach 2:
The system enables self-service by using the Fischer-Tropsch tail gas and water themselves as the recycling medium, without requiring external saturators or pure oxygen inputs. The tail gas is superheated and mixed with water to maintain vapor phase recycling back to the syngas preparation unit
2Ease of manufacture
If Fischer-Tropsch water is injected into tail gas without superheating, then the recycling process is simpler, but condensation occurs causing corrosion and catalyst deactivation
Solution Approach 1:
The invention changes the temperature parameter by superheating the Fischer-Tropsch tail gas before mixing with water. This parameter change ensures the mixture remains in vapor phase, preventing condensation that would cause corrosion and catalyst deactivation, while maintaining reliable catalyst effectiveness
Solution Approach 2:
The tail gas is superheated in advance before the water injection occurs. This preliminary heating action ensures that when water is injected, the mixture maintains vapor phase conditions, preventing harmful condensation downstream
3Ease of operation
If the H2/CO ratio is not adjusted in the recycled gas, then the process is simpler, but the Fischer-Tropsch synthesis efficiency decreases
Solution Approach 1:
The invention implements feedback by using a water-gas shift reactor to adjust the H2/CO ratio in the recycled gas based on the composition of the tail gas. This feedback mechanism optimizes the syngas composition for Fischer-Tropsch synthesis, improving synthesis efficiency while maintaining reasonable operational 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 enables efficient production of syngas without the need for saturators or pure oxygen, reducing costs and minimizing unwanted by-products, while maintaining catalyst effectiveness and optimizing the H2/CO ratio for Fischer-Tropsch synthesis.
Implementation Method 1
superheating at least a first portion of the FT tail gas
Implementation Method 2
a water-gas shift reactor, downstream of the injection of the at least a portion of the FT tail gas. The water-gas shift reactor forms a converted mixed gas from the mixed gas
Data Source
AI summary
A method of producing reformed gas as part of a Fischer-Tropsch (“FT”) hydrocarbon synthesis is disclosed, including the steps of superheating at least a first portion of an FT tail gas produced as a by-product of an FT synthesis process, and forming a mixed gas by injecting at least a portion of an FT water stream, produced as a by-product of an FT synthesis process, into the superheated FT tail gas to form a mixed gas. The mixed gas is used as a feed to a front end of a syngas preparation unit. The amount of at least a portion of the FT water stream is selected to keep the mixed gas at least mostly and preferably entirely in a vapor phase. In some embodiments, a water-gas shift reactor converts the mixed gas to a converted mixed gas upstream of the front end. Other methods, apparatuses and systems are disclosed.