Ammonia Separation via Pressure Swing Adsorption in Cracking Gas
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Solution Overview
Problem
Current ammonia cracking processes for producing forming gas face challenges in efficiently separating unreacted ammonia, which leads to the production of harmful nitrogen oxides when used as fuel, and result in economic inefficiencies due to the regeneration or disposal of ammonia/water mixtures.
Innovation Solution
The implementation of pressure swing adsorption (PSA) and temperature swing adsorption (TSA) to selectively separate ammonia from the cracked gas, producing a residual gas with reduced ammonia content that can be further treated to obtain forming gas suitable for use as fuel.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If water scrubbing is used to separate ammonia from cracked gas, then ammonia content is reduced, but water consumption increases and ammonia/water mixture disposal becomes costly
Solution Approach 1:
The patent employs pressure swing adsorption to separate ammonia from cracked gas by utilizing changes in pressure parameters. The adsorbent material's ammonia adsorption capacity varies with pressure, allowing selective ammonia removal without requiring large amounts of water. This resolves the contradiction by achieving ammonia reduction while minimizing water consumption and waste mixture disposal needs.
2Loss of energy
If ammonia is not extensively separated before combustion, then energy recovery is maximized, but nitrogen oxide emissions increase
Solution Approach 1:
The patent implements continuous pressure swing adsorption separation to maintain ammonia content in the cracked gas below 1000 ppm throughout the process. This continuous removal ensures that when the remaining ammonia is combusted for energy recovery, nitrogen oxide emissions are kept within acceptable limits. The process achieves both energy recovery and emission control by maintaining ammonia at low but non-zero levels.
3Quantity of substance
If pressure swing adsorption is implemented for ammonia separation, then ammonia removal efficiency increases, but device complexity increases
Solution Approach 1:
The pressure swing adsorption system is designed to be self-regenerating, where the adsorbent material automatically regenerates through pressure cycling without requiring external intervention. The system uses its own operational cycles to restore adsorbent capacity, reducing the need for complex external regeneration equipment and simplifying the overall device structure while maintaining high ammonia separation efficiency.
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 method effectively reduces the ammonia content in the forming gas, minimizing the production of nitrogen oxides and improving the economic viability by eliminating the need for costly regeneration or disposal of ammonia/water mixtures.
Implementation Method 1
the cooled cracked gas is fed at an inlet pressure to one of several adsorbers of a pressure swing adsorber. Each adsorber is filled with a material that adsorbs and retains the ammonia contained in the cracked gas while allowing hydrogen and nitrogen to pass largely unhindered.
Implementation Method 2
Each adsorber is filled with a material that adsorbs and retains the ammonia contained in the cracked gas
Implementation Method 3
an ammonia-containing feedstock is fed to a cracking reactor in order to thermally crack ammonia with catalytic support and to obtain a cracked gas comprising hydrogen, nitrogen and ammonia
Implementation Method 4
thermally crack ammonia with catalytic support
Implementation Method 5
The combustion chamber is heated by one or more burners powered by imported fuel, which provide heat for the endothermic cracking of the ammonia passing through the cracking tubes
Implementation Method 6
The resulting reaction 2NH3 ↔ N2 + 3H2 is endothermic (ΔH=46.2 kJ/mol)
Data Source
Figure 1
AI summary
The invention relates to a method and a device for producing a product gas (forming gas) (7) consisting largely of hydrogen and nitrogen, wherein an ammonia-containing feedstock (1) is fed to a cracking reactor (S) in order to thermally crack ammonia with catalytic support and to obtain a cracked gas (3) comprising hydrogen, nitrogen, and ammonia, from which ammonia is adsorptively separated in a separation device (T) to form the forming gas (7). Characteristic here is that the cracked gas (3) is treated in the separation device (T) by pressure swing adsorption (PWA) (D) in order to selectively separate ammonia and to obtain a PWA residual gas (4) containing the separated ammonia and a cracked gas (5) with a reduced ammonia content, which forms the forming gas or from which the forming gas (7) is obtained by further treatment.