Synthesis Gas Production Using Membrane CO2 Separation and Return
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Solution Overview
Problem
Existing methods for producing synthesis gas from natural gas, such as autothermal reforming (ATR), partial oxidation (PDX), and steam reforming (SMR), incur high investment and operating costs due to the use of gas scrubbing techniques like methanol or amine scrubbing for carbon dioxide separation, which negatively impact economic efficiency.
Innovation Solution
The method involves using a membrane to separate carbon dioxide from synthesis raw gas, allowing it to be directly compressed with natural gas and returned to the thermochemical conversion process, eliminating the need for a separate carbon dioxide compressor, and optionally using a membrane permeable to hydrogen for sulfur removal, followed by acid gas scrubbing to achieve the desired purity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If gas scrubbing is used to separate carbon dioxide from synthesis raw gas, then carbon dioxide separation is achieved, but investment and operating costs increase significantly
Solution Approach 1:
The patent employs a membrane with selective permeability properties to separate carbon dioxide from synthesis raw gas. The membrane allows carbon dioxide to pass through while retaining other gases, replacing the complex gas scrubbing system with a simpler membrane-based separation process that reduces both investment and operating costs.
Solution Approach 2:
The patent replaces the mechanical gas scrubbing system (which requires detergents, absorption towers, and regeneration systems) with a membrane separation system that operates on physical permeability differences. This substitution eliminates the need for chemical absorbents and complex mechanical regeneration equipment, thereby reducing costs.
2Adaptability or versatility
If carbon dioxide is compressed for return to the conversion process after gas scrubbing, then carbon dioxide is reused, but additional equipment and energy costs increase
Solution Approach 1:
The patent combines the carbon dioxide separation and compression functions into a single integrated membrane module. The membrane not only separates carbon dioxide from synthesis raw gas but also inherently compresses it to the required pressure for return to the conversion process, eliminating the need for separate compression equipment and reducing energy consumption.
Solution Approach 2:
The membrane system performs multiple functions simultaneously: it acts as both a separation barrier and a compression device. By utilizing the pressure difference across the membrane during the separation process, the system achieves both carbon dioxide recovery and compression without requiring additional dedicated equipment, thereby reducing overall device complexity.
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 costs and enhances economic efficiency by simplifying carbon dioxide separation and compression, thereby improving the overall synthesis gas production process.
Implementation Method 1
the synthesis raw gas is conducted across a membrane on the retentate side, which membrane is permeable to carbon dioxide
Implementation Method 2
A membrane suitable for this purpose has a high permeability to and selectivity for carbon dioxide, while it is either impermeable or is significantly less permeable to all or at least most of the remaining components
Implementation Method 3
The greater this difference, the greater the permeability and the more effective the separation of carbon dioxide from the carbon dioxide-containing gas mixture. In order to prevent a reduction in this pressure difference due to the accumulation of carbon dioxide on the permeate side, the permeate side is swept with a purge gas that has a low CO2 pressure.
Implementation Method 4
the carbon dioxide separated via the membrane is compressed together with the natural gas so that, for its return, the use of a separate carbon dioxide compressor may be dispensed with
Implementation Method 5
the natural gas is subsequently converted thermochemically to form a synthesis raw gas which, in addition to carbon monoxide and hydrogen, also contains a larger amount of carbon dioxide and water
Data Source
AI summary
A method and to a device for producing a synthesis gas, which contains carbon monoxide and hydrogen, wherein natural gas having a first carbon dioxide partial pressure (CO2 pressure) is provided and is processed inter alia by means of a pressure increase to form a natural gas input for a thermochemical conversion, in which a synthesis raw gas having a second CO2 pressure greater than the first CO2 pressure is produced, from which synthesis raw gas at least carbon dioxide is subsequently separated in order to obtain the synthesis gas and carbon dioxide, at least some of which is returned and is used in the thermochemical conversion of the natural gas input. To separate carbon dioxide, the synthesis raw gas is conducted across the one membrane on the retentate side, which membrane is permeable to carbon dioxide and is flushed on the permeate side by the provided natural gas.