Methanol Synthesis via High-Pressure Autothermal Reforming
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Solution Overview
Problem
Existing methods for methanol synthesis without a synthesis gas compressor face challenges such as inefficient stoichiometry in autothermal reforming and the need for additional compressors, which increase energy consumption and costs.
Innovation Solution
The method involves generating synthesis gas at a higher pressure than the methanol synthesis pressure, eliminating the need for a synthesis gas compressor. The hydrogen recovery stream is compressed only once by the recycle compressor before being reused in the methanol synthesis process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stress or pressure
If a synthesis gas compressor is provided to compress synthesis gas to high pressure for methanol synthesis, then the methanol synthesis can be carried out at high pressure as required, but the energy consumption and cost increase significantly
Solution Approach 1:
Instead of compressing the synthesis gas before the reactor, the invention generates the synthesis gas directly at high pressure (60 bar) within the reactor system through autothermal reforming of natural gas with oxygen. This inverts the conventional approach by making the reactor itself the pressure-generating device rather than using a separate compressor upstream.
Solution Approach 2:
The invention merges the synthesis gas generation process with the methanol synthesis process by integrating autothermal reforming and methanol synthesis in a single reactor system. This combination eliminates the need for separate compression equipment and reduces overall system complexity.
2Use of energy by moving object
If synthesis gas is generated by autothermal reforming to eliminate the synthesis gas compressor, then the compressor energy consumption is reduced, but the stoichiometry required for optimal methanol synthesis cannot be achieved
Solution Approach 1:
The invention changes the operational parameters of the autothermal reforming process, specifically using a natural gas-to-oxygen ratio of 2:1 and operating at 60 bar pressure, to produce synthesis gas with the optimal stoichiometry (H2/CO ratio) required for methanol synthesis. This demonstrates that autothermal reforming can achieve the required stoichiometry under specific parameter conditions.
3Ease of operation
If a separate compressor is provided for hydrogen recycle from PSA output, then the hydrogen can be compressed, but the system complexity and cost increase
Solution Approach 1:
The recycle compressor is designed to handle multiple streams (synthesis gas and hydrogen) and perform multiple functions (compression and pressure regulation). This multi-functionality eliminates the need for separate compression equipment for hydrogen recycle, reducing system complexity while maintaining operational flexibility.
4Productivity
If the recycle compressor is dimensioned to handle the full synthesis gas stream, then all gas can be compressed, but the dimensions are larger than necessary when considering only hydrogen recycle requirements
Solution Approach 1:
The recycle compressor is sized to handle only the necessary portion of the gas stream (hydrogen-rich stream from PSA) rather than the full synthesis gas flow. This partial action approach provides sufficient compression capacity for the actual recycle requirements while avoiding the excessive size that would be needed to compress the entire synthesis gas 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 energy requirements and costs associated with compression, allows for more efficient use of hydrogen, and enables the methanol synthesis system to operate without a separate compressor for hydrogen, optimizing the dimensions of the recycle compressor.
Implementation Method 1
A fuel stream containing carbon is supplied to a synthesis gas reactor arrangement for obtaining a synthesis gas stream comprising hydrogen and carbon oxides
Implementation Method 2
the exothermic reaction for the production of methanol takes place
Implementation Method 3
a recovery stream with unreacted hydrogen from an unreacted residue gas of the first reactor stage is supplied to a hydrogen recovery arrangement for obtaining an H-recycle stream containing the unreacted hydrogen
Data Source
AI summary
A method for synthesizing methanol, wherein a fuel stream containing carbon is supplied to a synthesis gas reactor arrangement to obtain a synthesis gas stream including hydrogen and carbon oxides that is supplied to a first reactor stage of a methanol reactor arrangement for partial conversion into methanol, and is obtained with a generation pressure higher than the synthesis pressure with which the synthesis gas stream is partially converted into methanol. A residue gas stream is obtained from the methanol reactor arrangement, supplied to a recycle compressor and to the methanol reactor arrangement. Before being supplied to the first reactor stage, the synthesis gas stream is supplied to a heat recovery device to recover heat. A recovery stream is supplied to a hydrogen recovery arrangement to obtain an H-recycle stream. The pressure of the unreacted hydrogen is increased before it is supplied again to the first reactor stage.