Ammonia Cracking via Condensing Steam for Lower Inlet Temperatures
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Solution Overview
Problem
Existing ammonia splitting processes face limitations in conversion rate due to high inlet temperatures, material costs, and temperature inhomogeneities, particularly in adiabatic pre-cracking steps, leading to inefficient hydrogen production.
Innovation Solution
Employing a condensable medium, such as water steam, to provide heat for the endothermic cracking reaction, allowing for a more homogeneous temperature distribution and reducing the need for high inlet temperatures, thereby improving conversion rates and enabling the use of less costly materials.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If high inlet temperatures (500-650°C) are used in adiabatic pre-cracker to improve ammonia conversion rate, then conversion rate is improved, but material costs increase and temperature inhomogeneities occur
Solution Approach 1:
The patent employs the phase transition of water from liquid to vapor (steam generation) to provide heat for the endothermic cracking reaction. The steam is generated in a steam generator using waste heat from the cracker flue gas, and then injected into the cracker to maintain homogeneous temperature distribution without requiring high inlet temperatures, thus avoiding the need for expensive high-grade materials while maintaining good conversion rates
Solution Approach 2:
The patent introduces steam as an intermediary medium to transfer heat to the cracking reaction. Instead of directly heating the ammonia feed to high temperatures, steam serves as a heat carrier that provides the necessary thermal energy at lower temperatures, eliminating the need for expensive high-temperature resistant materials while maintaining effective cracking conditions
2Productivity
If high inlet temperatures are used in adiabatic pre-cracker to improve ammonia conversion, then conversion rate is improved, but temperature inhomogeneities and limited heat capacity occur
Solution Approach 1:
The patent utilizes the phase transition of water to steam and the subsequent condensation of steam to provide controlled, homogeneous heating throughout the cracker. The steam injection ensures uniform temperature distribution, avoiding the temperature inhomogeneities that occur in adiabatic processes while maintaining high conversion rates
Solution Approach 2:
The patent implements continuous steam generation and injection to maintain stable, homogeneous temperature conditions throughout the cracking process. The steam is continuously generated from waste heat and injected into the cracker, providing sustained thermal energy that ensures uniform temperature distribution and consistent conversion rates without the fluctuations seen in adiabatic processes
3Loss of energy
If adiabatic pre-cracking is used to reduce heat duty in main cracker, then energy consumption is reduced, but conversion rate remains limited due to slow reaction at lower temperatures
Solution Approach 1:
The patent uses steam generation through phase transition of water to provide the necessary heat for cracking at lower temperatures. This approach maintains good conversion rates by providing controlled thermal energy through steam injection, eliminating the need for high inlet temperatures while achieving effective ammonia conversion
Solution Approach 2:
The patent introduces steam as an intermediary heat transfer medium that efficiently delivers thermal energy to the cracking reaction at lower temperatures. This steam-mediated heating process achieves good conversion rates without requiring the high inlet temperatures of adiabatic processes, thereby reducing the heat duty requirement in the main cracker while maintaining high productivity
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 higher conversion rates with a more efficient and compact design, utilizing latent heat from condensation to drive the cracking reaction forward, and allows for precise temperature control, reducing material costs and optimizing the cracker unit's operation.
Implementation Method 1
condensing at least partially said condensable medium
Implementation Method 2
During the condensation of the condensable medium from vapor to liquid, a latent heat is released to the cracker unit
Implementation Method 3
performing an endothermic cracking reaction of the ammonia feed in a cracker unit for producing a cracked gas comprising hydrogen and nitrogen
Data Source
Figure 1~3
Figure 4
AI summary
Process for producing hydrogen from ammonia, comprising the steps : i) providing an ammonia feed, ii) providing a condensable medium, preferably water steam, iii) performing an endothermic cracking reaction of the ammonia feed in a cracker unit (18, 28) for producing a cracked gas comprising hydrogen and nitrogen, iv) condensing at least partially said condensable medium, v) providing heat from the condensation to the endothermic cracking reaction, vi) recovering hydrogen from said cracked gas or from a gas derived from said cracked gas.