Methanol Synthesis Gas Recycling Before Compression
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Solution Overview
Problem
In carbon dioxide-based methanol synthesis, the decompression gas stream from the low-pressure separator cannot be efficiently recycled to the synthesis gas input stream due to pressure differences, requiring separate and costly compression, making it economically and technologically infeasible.
Innovation Solution
A process that combines the decompression gas stream with either the hydrogen-rich or carbon dioxide-rich reactant gas stream before compression to synthesis pressure, allowing for separate or combined compression of these streams, thereby eliminating the need for dedicated compressors and enabling flexible operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If the decompression gas stream is recycled to the synthesis gas input stream, then carbon dioxide emissions are reduced and resource utilization is improved, but the pressure difference between the decompression gas stream and synthesis gas input stream requires additional compression equipment and energy consumption
Solution Approach 1:
The patent combines the decompression gas stream with the synthesis gas input stream before compression to a single mixed gas stream. This merging allows the use of one compression unit to handle both streams simultaneously, eliminating the need for separate compression equipment for each stream and reducing overall device complexity while enabling recycling of the decompression gas stream
Solution Approach 2:
The compression unit is designed to handle both the synthesis gas input stream and the decompression gas stream together as a mixed stream. This multi-functional approach allows a single compressor to serve multiple purposes - compressing both reactant streams and the recycled decompression gas - thereby reducing the number of dedicated compression equipment pieces needed in the system
2Reliability
If separate compression is used for hydrogen-rich and carbon dioxide-rich reactant gas streams, then each stream can be compressed to synthesis pressure independently, but the cost and complexity of the compression system increases
Solution Approach 1:
The patent merges the decompression gas stream with one of the reactant gas streams (hydrogen-rich or carbon dioxide-rich) before compression. This creates a single mixed gas stream that is compressed together, reducing the number of separate compression units needed while maintaining the ability to achieve synthesis pressure for all components
3Ease of operation
If a dedicated compressor is installed for the decompression gas stream, then the decompression gas can be compressed to synthesis pressure, but the cost and energy consumption increases due to the small size and low pressure of the decompression gas stream
Solution Approach 1:
The decompression gas stream is combined with the larger volume reactant gas stream before compression. This merging allows the compression system to handle the decompression gas as part of the main stream, utilizing the existing compression infrastructure for a larger total volume rather than compressing a small separate stream, thereby reducing energy consumption per unit volume
Solution Approach 2:
The compression system is designed to handle multiple gas streams with different characteristics (reactant gases and decompression gas) together in a single compression process. This multi-functional approach allows the system to optimize compression for the largest stream while inadvertently handling the smaller decompression stream efficiently, avoiding the need for dedicated compression equipment for the small stream
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 reduces the need for additional compression, enhances flexibility in stream management, and lowers carbon dioxide emissions and energy consumption, making the process more efficient and cost-effective.
Implementation Method 1
reacting the synthesis gas stream at synthesis pressure in a reaction apparatus over a solid methanol synthesis catalyst to afford a methanol-containing product gas stream
Implementation Method 2
combining the decompression gas stream with either the hydrogen-rich or carbon dioxide-rich reactant gas stream before compression to synthesis pressure
Implementation Method 3
In a first high-pressure separator crude methanol is separated as a liquid and at least a portion of the remaining gaseous phase containing unreacted synthesis gas is recycled
Implementation Method 4
The raw methanol discharged from the high-pressure separator is introduced into a low-pressure separator after pressure reduction. The pressure reduction causes further unconverted synthesis gas to be outgassed from the raw methanol
Implementation Method 5
introducing the first raw methanol stream into a second separator, wherein the pressure in the second separator is reduced relative to the pressure in the first separator, to obtain in the second separator a second raw methanol stream as a liquid phase and the decompression gas stream as a gaseous phase
Data Source
AI summary
A process for producing methanol from a hydrogen-rich and a carbon dioxide-rich reactant gas stream. According to the invention a decompression gas stream obtained in a low-pressure separator and containing hydrogen and carbon dioxide is recycled to one of the two reactant gas streams or the decompression gas stream is divided over two substreams and the respective substreams are recycled to the respective reactant gas streams. Combination of these streams is carried out before compression to synthesis pressure and before formation of the actual synthesis gas stream.