Oxygen Transport Membrane Reforming with Synthesis Gas Recycle
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Solution Overview
Problem
Conventional oxygen transport membrane based reforming systems for producing synthesis gas face issues such as excessive carbon formation, high operational temperatures, costly membrane modules, and reliability and durability concerns, leading to commercialization challenges.
Innovation Solution
A reactively-driven oxygen transport membrane based reforming system with modifications to the steam and hydrocarbon feed streams to optimize steam to carbon ratios and temperatures, combined with a heat recovery train and synthesis gas recycle loop, to mitigate carbon formation and enhance system reliability and durability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional oxygen transport membrane based reforming systems are used to produce synthesis gas, then synthesis gas production is achieved, but excessive carbon formation occurs and operational temperatures become excessively high
Solution Approach 1:
The patent applies parameter changes by optimizing the steam-to-hydrocarbon ratio in the feed stream and controlling the operational temperature within a specific range (600-900°C). By adjusting these parameters, the system achieves effective synthesis gas production while minimizing carbon formation and avoiding excessively high temperatures that would cause harmful effects.
Solution Approach 2:
The patent introduces an intermediary substance (steam) that mediates between the hydrocarbon feed and the oxygen transport membrane. The steam acts as a buffer that prevents direct excessive carbon formation by participating in reforming reactions and controlling the chemical environment, thereby reducing harmful carbon deposits while maintaining productivity.
2Productivity
If conventional oxygen transport membrane based reforming systems are used, then synthesis gas is produced, but the membrane modules are costly and reliability and durability concerns arise
Solution Approach 1:
The patent addresses reliability and durability by optimizing operational parameters including temperature control (600-900°C), pressure management, and steam-to-hydrocarbon ratio. These parameter changes prevent conditions that would degrade the membrane modules, thereby extending their service life and improving system reliability while maintaining synthesis gas production.
Solution Approach 2:
The patent applies beforehand cushioning by implementing a pre-reforming stage that prepares the feed stream before it reaches the oxygen transport membrane. This pre-treatment cushions the membrane from harsh conditions and potential damage, ensuring more reliable and durable operation while maintaining productivity.
3Reliability
If steam and hydrocarbon feed streams are conditioned to optimize steam to carbon ratios and temperatures, then carbon formation is reduced and system durability is improved, but additional process steps are required
Solution Approach 1:
The patent merges the steam injection and heating functions into an integrated feed preparation system. By combining these operations and optimizing them work together, the system achieves reduced carbon formation and improved durability without proportionally increasing device complexity. The merged system handles multiple functions in a coordinated manner.
Solution Approach 2:
The patent uses parameter changes to simplify the process by establishing optimal ranges for temperature (600-900°C) and steam-to-carbon ratio. By defining these parameters, the complex task of preventing carbon formation is reduced to controlling a few key variables, making the process more manageable despite the additional conditioning steps.
4Quantity of substance
If pre-reforming is performed adiabatically to convert higher hydrocarbons, then methane and synthesis gas are produced, but the pre-reformed feedstock leaves at a much lower temperature than the feedstock entering
Solution Approach 1:
The patent uses steam as an intermediary to transfer heat to the pre-reformed feedstock. The steam, which is heated to high temperatures, serves as a heat carrier that raises the temperature of the cooled pre-reformed gas back to the required operational range (600-900°C) without requiring additional fossil fuel combustion.
Solution Approach 2:
The patent replaces the conventional mechanical/thermal heating system (furnaces or burners) with a thermal energy transfer system using steam as the medium. This substitution eliminates the need for separate heating equipment and integrates temperature recovery into the process flow, efficiently restoring the temperature of pre-reformed feedstock.
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
The system achieves reduced methane slip, lower hydrocarbon feed requirements, increased oxygen flux, and improved durability by conditioning the steam and hydrocarbon feed streams, resulting in a more efficient and reliable synthesis gas production process with reduced oxygen requirements.
Implementation Method 1
A typical oxygen transport membrane has a dense layer that, while being impervious to air or other oxygen containing gas, will transport oxygen ions when subjected to an elevated operational temperature and a difference in oxygen partial pressure across the membrane
Implementation Method 2
Pre-reforming is a catalyst based process for converting higher hydrocarbons to methane, hydrogen, carbon monoxide and carbon dioxide
Implementation Method 3
the exothermic oxidation process that occurs at the permeate side of the oxygen transport membranes and the endothermic reforming reaction which occurs in the presence of the reforming catalyst
Implementation Method 4
supply the endothermic heating requirements of the steam methane reforming reactions
Implementation Method 5
the synthesis gas is produced in a fired reformer in which natural gas and steam is reformed in nickel catalyst containing reformer tubes at high temperatures (e.g., 850° C. to 1000° C.)
Data Source
AI summary
A method and system for producing a synthesis gas in an oxygen transport membrane based reforming system that utilizes a combined feed stream having a steam to carbon ratio between about 1.6 and 3.0 and a temperature between about 500° C. and 750° C. The combined feed stream is comprised a pre-reformed hydrocarbon feed, superheated steam, and a reaction product stream created by the reaction of a hydrogen containing stream reacted with the permeated oxygen at the permeate side of the oxygen transport membrane elements and wherein the hydrogen containing stream is a recycled portion of the synthesis gas.