Syngas H2/CO Ratio Control via CO2 Recirculation Reforming
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Solution Overview
Problem
Current methods for generating syngas with a desired H2/CO ratio of 2 or less are complex and expensive, involving autothermal reforming with steam and oxygen or methane reforming followed by pressure swing absorption, which are inefficient and costly.
Innovation Solution
Generating CO2 in a reforming furnace by combusting natural gas with a mixture of external O2 and recirculated CO2, then splitting and processing the high-CO2 gas to achieve the desired H2/CO ratio through two separate reformers, minimizing nitrogen content and external O2 usage, and utilizing the CO2 as a reforming oxidant.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If autothermal reforming with steam and oxygen is used to generate syngas with H2/CO ratio of 2 or less, then the desired H2/CO ratio is achieved, but the process complexity and cost increase significantly
Solution Approach 1:
The process is divided into two separate reformers: a first reformer that produces CO2-rich gas by combusting natural gas with external oxygen, and a second reformer that uses this CO2-rich gas as oxidant to produce syngas with the desired H2/CO ratio. This segmentation eliminates the need for complex autothermal reforming systems while achieving the target syngas composition.
Solution Approach 2:
Instead of discarding CO2 as a waste product, the system recovers and recycles CO2 from the first reformer's flue gas to serve as the oxidant in the second reformer. This creates a closed-loop system that reduces external oxygen requirements and simplifies the overall process while maintaining the desired H2/CO ratio.
2Manufacturing precision
If pressure swing absorption is used to remove hydrogen and reduce H2/CO ratio from 3 to 2, then the desired H2/CO ratio is achieved, but the process becomes more complex and expensive
Solution Approach 1:
The system performs preliminary action by generating CO2-rich gas in the first reformer before it enters the second reformer. This pre-prepared CO2-rich atmosphere eliminates the need for post-reforming hydrogen removal operations like pressure swing absorption, as the desired H2/CO ratio is achieved directly in the second reformer's output.
3Quantity of substance
If CO2 is obtained via purchase through pipeline or captured from reformer flue gas, then the required CO2 is available, but the cost increases significantly
Solution Approach 1:
The system practices self-service by generating its own CO2 supply internally through the first reformer's combustion process. The CO2 produced is then recycled and used as oxidant in the second reformer, eliminating the need to purchase CO2 from external pipelines or invest in expensive CO2 capture systems from flue gas.
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 simplifies and cost-effectively produces syngas with the required H2/CO ratio for direct use in Fischer Tropsch GTL processes, reducing nitrogen content in the syngas and minimizing external O2 usage, while allowing for efficient CO2 recycling and utilization.
Implementation Method 1
combusting natural gas with a mixture of O2 from an external source and CO2 that is recirculated from a reforming furnace; wherein the combustion of O2 with natural gas produces CO2 and water (H2O)
Implementation Method 2
The CO2 that accompanies the O2 acts as an inert constituent and coolant, and is continually recirculated from the reforming furnace to a heat exchanger
Implementation Method 3
then to a direct contact water scrubber or the like, which condenses most of the water
Implementation Method 4
From there, the first stream is then mixed with steam and natural gas, and is sent as a process gas to reformer tubes where the CO2 and H2O reform the methane and small amounts of other hydrocarbons to H2 and CO
Data Source
AI summary
Processes that generate syngas or reformed gas that have the desired H2/CO ratio, such that they can be used directly for producing higher value liquids, such as using a FT GTL process. The systems and methods of the present invention are simpler and more cost effective than conventional systems and methods. The systems and methods of the present invention generate the required CO2 in a reforming furnace by combusting natural gas with a mixture of O2 from an external source and CO2 that is recirculated from a reforming furnace. A second application of the natural gas combustion with external O2 mixed with recirculated CO2 in the reformer burners can be utilized in a DR process. The reformed gas or syngas containing H2 and CO is used to reduce iron oxide to metallic iron in a shaft furnace, for example.