Parallel Bulk Methanation Zones for SNG Capacity
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Solution Overview
Problem
Current SNG production processes face limitations in capacity and efficiency due to the need for parallel reactors and high recycle gas flow, especially in large-scale plants, which increases capital and operational costs and complicates design and installation.
Innovation Solution
The process involves feeding synthesis gas to multiple bulk methanators in parallel, both within and outside the recycle gas loop, with different feed streams at varying pressures and compositions, allowing for higher capacity without parallel equipment and reducing recycle flow and power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If multiple parallel reactors are used to increase SNG production capacity, then productivity increases, but device complexity and capital costs increase
Solution Approach 1:
The patent divides the methanation process into two distinct zones: a first bulk methanation zone with multiple parallel methanators and a second bulk methanation zone with a single methanator. This segmentation allows the system to handle multiple synthesis gas feed streams of different pressures and compositions through different zones, increasing overall capacity while avoiding the need for complete parallel duplication of all equipment. The divided zone structure enables independent optimization of each zone based on feed stream characteristics.
2Temperature
If high recycle gas flow is used to control exothermic reactions, then temperature control improves, but power consumption increases
Solution Approach 1:
The patent applies different operational characteristics to different zones: the first bulk methanation zone operates with high recycle gas flow to effectively control the highly exothermic methanation reactions, while the second bulk methanation zone operates with lower or no recycle flow since it handles partially methanated gas with lower reaction intensity. This local differentiation optimizes temperature control where needed while minimizing unnecessary energy consumption in zones where it is less critical.
3Adaptability or versatility
If synthesis gas feeds at different pressures are processed separately, then processing flexibility improves, but device complexity increases due to separate trains
Solution Approach 1:
The patent creates a unified methanation system that can simultaneously process multiple synthesis gas feed streams with different pressures and compositions through different zones. The first bulk methanation zone handles high-pressure feeds while the second zone handles lower-pressure feeds, with both zones contributing to a common SNG product stream. This multi-functional design eliminates the need for completely separate processing trains while maintaining the ability to accommodate various feed conditions.
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 higher capacity SNG production with lower capital and operational costs, flexible design, and simplified installation, while accommodating different feed stream pressures and compositions.
Implementation Method 1
each methanator containing a methanation catalyst such that the feed streams are at least partially methanated
Implementation Method 2
recirculating the first portion in a recirculation loop to the first bulk methanator of the first bulk methanation zone to dilute the first synthesis gas feed stream
Implementation Method 3
The methanation of the syngas involves the following, highly exothermic reactions: CO + 3H2 → CH4 + H2O ΔH = minus 206 kJ/mol; CO2 + 4H2 → CH4 + 2H2O ΔH = minus 165 kJ/mol
Data Source
Figure 1
AI summary
A process is described for producing a substitute natural gas comprising the steps of: feeding a first synthesis gas feed stream comprising hydrogen, methane, carbon monoxide and/or carbon dioxide in parallel to two or more bulk methanators in a first bulk methanation zone comprising a first bulk methanator and a final bulk methanator, feeding a second synthesis gas feed stream comprising hydrogen, carbon monoxide and/or carbon dioxide to one or more bulk methanators in a second bulk methanation zone comprising a first bulk methanator, each bulk methanator containing a methanation catalyst such that the feed streams are at least partially methanated, dividing the methanated gas stream recovered from the final bulk methanator in the first bulk methanation zone into a first portion and a second portion, recirculating the first portion in a recirculation loop to the first bulk methanator of the first bulk methanation zone to dilute the first synthesis gas feed stream fed to said first bulk methanator, and feeding the second portion to the first bulk methanator of the second bulk methanation zone to dilute the second synthesis gas feed stream fed to said first bulk methanator, wherein the feed pressure of the second synthesis gas feed stream is lower than the feed pressure of the first synthesis gas feed stream and the difference in pressure between the first and second feed streams is at least the pressure drop through the first bulk methanation zone.