Integrated Dimethyl Ether Production via Reverse Flow Reforming
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Solution Overview
Problem
Conventional systems for producing dimethyl ether from natural gas are costly due to air separation, autothermal reforming, and significant internal product recycle, necessitating a more integrated and efficient process.
Innovation Solution
An integrated method involving natural gas reforming to syngas in a reverse flow reactor, followed by conversion to dimethyl ether using a catalyst system with in-situ steam cofeeding to achieve improved carbon and thermal efficiency, with steam controlling the production of carbon dioxide for recycling and minimizing hydrocarbon and oxygenate selectivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional air separation and autothermal reforming processes are used to produce dimethyl ether from natural gas, then dimethyl ether production is achieved, but operating costs and equipment costs increase significantly
Solution Approach 1:
The patent combines multiple conventional process units (air separation unit, autothermal reformer, methanol synthesis reactor, dimethyl ether reactor) into an integrated system where natural gas is reformed and converted to dimethyl ether in a unified process flow. The reformer and methanol synthesis reactor are thermally integrated, and the dimethyl ether reactor is coupled with a separator and recycle stream, merging functions that were previously separate to reduce overall process complexity and cost.
Solution Approach 2:
The integrated process design allows the same system to perform multiple functions: the reformer produces syngas while providing heat, the methanol synthesis reactor converts syngas to methanol while managing equilibrium through thermal coupling, and the dimethyl ether reactor simultaneously converts methanol to dimethyl ether. This multi-functionality reduces the need for separate dedicated units for each conversion step.
2Reliability
If significant internal product recycle is implemented in methanol synthesis, then equilibrium limitations are addressed, but recycle ratio and equipment costs increase
Solution Approach 1:
The patent implements a recycle stream where unreacted gas from the dimethyl ether reactor is fed back to the methanol synthesis reactor inlet. This feedback loop allows unreacted syngas and methanol to be reused, improving overall conversion efficiency and addressing equilibrium limitations without requiring excessively high recycle ratios in the methanol synthesis step alone.
Solution Approach 2:
The integrated process maintains continuous conversion through thermal coupling between the reformer and methanol synthesis reactor, and continuous recycle of unreacted gases through the dimethyl ether reactor back to the methanol synthesis reactor. This continuous action ensures that equilibrium limitations are constantly overcome through thermal energy input and material reuse.
3Loss of substance
If steam is added as cofeed to control carbon dioxide production for recycling, then carbon efficiency improves to at least 85%, but process control complexity increases
Solution Approach 1:
The patent controls the amount of steam added as a cofeed to the reformer to optimize the carbon dioxide production and overall carbon efficiency. By adjusting the steam-to-natural gas ratio, the process achieves a balance where sufficient carbon dioxide is produced for recycling while maintaining high carbon efficiency of at least 85% in the dimethyl ether product.
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 method achieves high carbon efficiency of at least 85% and thermal efficiency of at least 70%, reducing the need for additional CO2 sources and enhancing catalyst stability by controlling steam addition and recycle streams.
Implementation Method 1
a reverse flow reactor receiving the natural gas supply stream, wherein the reverse flow reactor is adapted to convert the natural gas supply stream to a syngas stream comprising carbon monoxide and hydrogen gas
Implementation Method 2
contacting the syngas produced in the first reactor with a catalyst system in a second reactor to produce dimethyl ether and carbon dioxide
Implementation Method 3
supplying steam as a cofeed to at least one of the first reactor and the second reactor in an amount sufficient to achieve a Mm value of 1.4 to 1.8 wherein Mm=(H2−CO2+H2O)/(CO+CO2−H2O)
Data Source
AI summary
Integrated methods and systems are disclosed for the production of dimethyl ether. The method may include reforming natural gas to syngas in a first reactor; contacting the syngas produced in the first reactor with a catalyst system in a second reactor to produce dimethyl ether and carbon dioxide; and supplying steam as a cofeed to at least one of the first reactor and the second reactor in an amount sufficient to achieve a Mm value of 1.4 to 1.8 or to improve the hydrocarbon or oxygenate selectivity.