Method and device for producing an ammonia synthesis gas with a low carbon dioxide content
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing methods for producing a make-up gas for ammonia synthesis result in high carbon dioxide emissions and inefficient carbon capture, with only up to 90% of carbon dioxide being captured and released into the atmosphere, despite the need for higher capture rates due to legal requirements and penalties.
Innovation Solution
A cryogenic gas separation process using nitrogen scrubbing and selective gas fractionation to produce a hydrogen-rich, carbon monoxide-free make-up gas and a hydrogen-rich, low-carbon fuel gas, with controlled carbon content adjustment and minimized nitrogen usage, allowing for improved carbon capture and utilization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If acid gas scrubbing is used to separate carbon dioxide from synthesis gas, then carbon dioxide separation is achieved, but only up to 90% capture rate is possible with significant carbon dioxide still released into the atmosphere
Solution Approach 1:
The patent changes the operating parameters from conventional acid gas scrubbing to cryogenic temperature conditions, enabling near-complete carbon dioxide separation. By cooling the gas mixture to cryogenic temperatures and utilizing the different condensation temperatures of carbon dioxide and hydrogen, the system achieves over 90% carbon dioxide capture rate, with the separated carbon dioxide available for utilization rather than atmospheric release.
Solution Approach 2:
The patent exploits phase transitions at cryogenic temperatures to separate carbon dioxide from hydrogen. Carbon dioxide condenses at higher temperatures than hydrogen, allowing selective condensation and separation. This phase transition-based separation enables complete carbon dioxide capture while maintaining hydrogen purity for ammonia synthesis.
2Productivity
If conventional reforming and water gas shift are used to produce make-up gas, then hydrogen production is achieved, but high carbon dioxide emissions result
Solution Approach 1:
The patent applies cryogenic condensation to separate carbon dioxide from the synthesis gas produced during reforming and water gas shift. By cooling the gas stream to cryogenic temperatures, carbon dioxide selectively condenses while hydrogen remains gaseous, enabling efficient hydrogen production with simultaneous carbon dioxide capture and utilization.
Solution Approach 2:
The patent converts the harmful carbon dioxide emissions from reforming into a useful resource. The cryogenic separation process captures carbon dioxide in high purity form, which can then be utilized for various purposes such as chemical feedstock or carbonation processes, transforming the waste product into a valuable resource.
3Reliability
If methanation or pressure swing adsorption is used to remove carbon monoxide from raw hydrogen, then carbon monoxide-free make-up gas is produced, but additional process complexity and cost are incurred
Solution Approach 1:
The patent extracts carbon monoxide and other impurities from raw hydrogen during the cryogenic separation process. By removing these contaminants in the same step as carbon dioxide separation, the system achieves carbon monoxide-free make-up gas without requiring separate methanation or pressure swing adsorption units, thereby reducing overall process 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
The process achieves a higher carbon capture rate with reduced operational costs and efficient utilization of carbon dioxide, enabling nearly complete carbon dioxide disposal or recycling, suitable for producing 'blue' ammonia.
Implementation Method 1
at least a part of which is processed into a feed (cryogenic feed) for cryogenic gas separation, in which a hydrogen-rich, carbon monoxide-free first gas fraction is produced from the cryogenic feed
Implementation Method 2
the cryogenic gas separation with controlled carbon content adjustment and minimized nitrogen usage, allowing for improved carbon capture and utilization
Implementation Method 3
This gas is then subjected to a water-gas shift to convert the contained carbon monoxide with water to hydrogen and carbon dioxide, thereby producing a synthesis gas
Implementation Method 4
a hydrocarbon-containing feed is converted by reforming and water gas shift to a synthesis gas consisting largely of hydrogen and carbon dioxide and containing carbon monoxide
Implementation Method 5
reformed, for example, by partial oxidation, autothermal, or steam reforming, into a synthesis gas consisting largely of hydrogen, carbon monoxide, and carbon dioxide
Implementation Method 6
ammonia is synthesized almost exclusively from nitrogen and hydrogen using the Haber-Bosch process
Implementation Method 7
In the Haber-Bosch process, an ammonia synthesis gas consisting primarily of hydrogen and nitrogen, in which the two substances are present in the stoichiometric ratio of 3:1 for ammonia synthesis, is fed into an ammonia synthesis reactor at a pressure between 100 and 200 bar. With catalytic support, it is exothermically converted to ammonia in an ammonia reactor.
Implementation Method 8
This gas mixture leaves the ammonia reactor at a temperature between 400 and 450°C and is subsequently cooled in a series of heat exchangers to separate ammonia by condensation
Data Source
Figure 1
Figure 2
AI summary
The invention relates to a method and a device for producing a carbon monoxide-free make-up gas (15) for ammonia synthesis, wherein a hydrocarbon-containing feedstock (1) is converted by reforming (B) and water gas shift (G) into a synthesis gas (6) consisting largely of hydrogen and carbon dioxide and containing carbon monoxide, from which synthesis gas (6) is produced by separating carbon dioxide (7) to produce raw hydrogen (8), at least a portion of which is processed into a feedstock (cryogenic feedstock) (10) for cryogenic gas separation (K), in which a hydrogen-rich, carbon monoxide-free first gas fraction (11) is produced from the cryogenic feedstock (10), which is passed on as make-up gas or supplemented with nitrogen (14) to form make-up gas (15), and a hydrogen-rich and low-carbon second gas fraction is produced, which is used as fuel gas (13) to generate process heat.What is characteristic here is that the hydrogen-rich and carbon-poor second gas fraction (13) is obtained during the cryogenic gas separation (K) with a carbon content that is lower than that of the cryogenic feed (10) and higher than that of the hydrogen-rich, carbon monoxide-free first gas fraction (11).