Ammonia Cracking via Electrolysis Oxygen Combustion
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Solution Overview
Problem
Current ammonia cracking processes for producing hydrogen are not highly efficient, as they do not effectively integrate waste heat, which is crucial for efficiency, especially in areas with scarcity of renewable energy.
Innovation Solution
The process involves using water electrolysis to produce oxygen for a combustion reaction, which generates heat for the endothermic ammonia cracking reaction, thereby achieving autothermal cracking. This process also utilizes waste heat for steam generation and electricity production, enhancing overall efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If water electrolysis is used to produce oxidant for combustion reaction, then continuous supply of oxidant is ensured and overall efficiency increases, but device complexity increases due to integration of electrolyzer and heat integration systems
Solution Approach 1:
The patent combines the water electrolysis unit with the ammonia cracking system, integrating the oxidant production (oxygen from electrolysis) directly into the combustion reaction for heating. This merging ensures continuous oxidant supply while making the system self-sufficient for its thermal needs.
Solution Approach 2:
The water electrolysis unit serves multiple functions: it provides oxidant for the combustion reaction, generates hydrogen as a valuable product, and when integrated with waste heat, can contribute to steam generation. This multi-functionality justifies the added complexity by delivering multiple benefits from a single integrated system.
2Use of energy by moving object
If waste heat integration is implemented for steam generation and electricity production, then overall plant efficiency increases, but device complexity and initial investment increase
Solution Approach 1:
The patent recovers waste heat from the ammonia cracking process that would otherwise be discarded. This recovered heat is utilized for steam generation and can drive turbines for electricity production, thereby improving overall energy efficiency and reducing waste.
Solution Approach 2:
The system creates a feedback loop where waste heat from the cracking reaction is captured and reused for steam generation and power production, which in turn supports the electrolysis and cracking processes. This closed-loop approach maximizes energy utilization and justifies the additional system complexity.
3Object-generated harmful factors
If autothermal cracking is used for CO2-free hydrogen production, then environmental performance improves, but energy management complexity increases due to balancing exothermic and endothermic reactions
Solution Approach 1:
The patent converts the harmful CO2 emissions associated with conventional hydrogen production into a benefit by using autothermal cracking, which is CO2-free. The exothermic combustion reaction (which could be seen as a harmful side reaction) is actually utilized to provide the necessary heat for the endothermic cracking, turning a potential disadvantage into a useful heat source.
Solution Approach 2:
The system carefully controls the parameters of the combustion reaction (oxygen supply, temperature, residence time) to optimize the balance between exothermic heat generation and endothermic cracking. By adjusting these parameters, the system achieves CO2-free hydrogen production while managing the energy balance through the integrated electrolysis unit that provides precise oxygen control.
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 allows for CO2-free production of hydrogen, increases the overall efficiency of the plant by integrating waste heat, and provides a continuous supply of oxidant, ensuring efficient operation even during startup phases.
Implementation Method 1
performing a water electrolysis of the water feed stream in the electrolyzer, producing an oxygen product stream and an electrolysis hydrogen stream
Implementation Method 2
performing a combustion reaction with said oxidant stream, thereby generating heat
Implementation Method 3
heat produced in exothermic non-catalytic oxidation of ammonia by the following reaction 2 NH3 + 3/2 O2 → N2 + 3 H2O
Implementation Method 4
performing an endothermic reaction of ammonia cracking of the ammonia feed stream with said generated heat
Implementation Method 5
gaseous ammonia is dissociated into a mixture of hydrogen and nitrogen in the reversible reaction
Implementation Method 6
The electricity needed for the electrolysis can be at least partially produced from a steam turbine utilizing the waste heat from the ammonia cracking process
Data Source
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AI summary
The invention relates to a process (100) for the production of hydrogen from ammonia comprising the following steps: - providing a water feed stream to a water electrolyzer (101); - performing a water electrolysis (102) of the water feed stream in the electrolyzer, producing an oxygen product stream and an electrolysis hydrogen stream; - providing an ammonia feed stream to an ammonia cracking reactor (103); - providing an oxidant stream (105) and performing a combustion reaction (106) with said oxidant stream, thereby generating heat; - in the ammonia cracking reactor, performing an endothermic reaction of ammonia cracking (104) of the ammonia feed stream with said generated heat; characterized in that the oxidant stream comprises at least a portion of the oxygen product stream produced by the water electrolysis of the water feed stream.