Electrically Heated Adiabatic Ammonia Cracking Process
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Solution Overview
Problem
The existing methods for producing hydrogen gas from ammonia face challenges such as high energy costs, inefficient heat management, and environmental concerns due to ammonia combustion, which complicates the process and increases costs.
Innovation Solution
The process involves separating the ammonia cracking conversion into two distinct steps: an electrical heating step and a conversion step, using an adiabatic reactor with a catalyst bed, thereby allowing for customizable conversion rates and eliminating the need for fuel combustion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If ammonia combustion is used to provide heat for the endothermic cracking reaction, then the reaction medium can be heated to the required temperature, but nitrogen oxide is produced which is harmful when inhaled
Solution Approach 1:
The harmful combustion step is extracted and removed from the process. Instead of using ammonia combustion to heat the reaction medium, the patent uses an external heat source (furnace or heat exchanger) to provide the necessary thermal energy, thereby eliminating nitrogen oxide emissions while maintaining the required reaction temperature
Solution Approach 2:
An intermediary heat transfer medium is introduced between the heat source and the ammonia cracking reaction. The reaction medium is heated indirectly through heat exchange surfaces rather than direct combustion, allowing thermal energy transfer without direct contact between combustion products and the reaction mixture
2Use of energy by moving object
If a firebox with fuel combustion is used to heat the reactor, then the endothermic reaction can be sustained, but waste heat is generated requiring recovery systems and flue gas treatment
Solution Approach 1:
The system uses itself to provide heat. The endothermic cracking reaction products or the reactant stream itself serves as the heat transfer medium, circulating through the reactor where it absorbs heat directly from the reaction zone, eliminating the need for separate waste heat recovery systems
3Productivity
If the ammonia feedstock stream is heated to high temperature to achieve targeted conversion, then the cracking reaction efficiency increases, but significant energy is required to maintain the reaction
Solution Approach 1:
The patent implements continuous circulation of the ammonia feedstock stream through the reactor system. The stream continuously absorbs thermal energy from the endothermic reaction zone and transports it, maintaining continuous heat supply to the reaction without requiring intermittent heating cycles, thereby improving energy utilization efficiency
Solution Approach 2:
The patent optimizes the temperature profile along the reactor length rather than maintaining uniform high temperature throughout. The ammonia stream is gradually heated and reacts along the flow path, allowing the reaction to proceed at progressively lower temperatures, reducing the total energy input required while maintaining high conversion rates
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 simplifies the process, reduces energy costs, and enhances modularity, achieving higher conversion rates while minimizing environmental impact and operational complexity.
Implementation Method 1
an electrical heating step comprising heating in at least one electric heater the ammonia feedstock stream so as to produce a heated gas stream
Implementation Method 2
a conversion step comprising performing in at least one adiabatic reactor an endothermic cracking reaction of the heated gas stream
Implementation Method 3
said adiabatic reactor comprising at least one catalyst bed performing said endothermic cracking reaction of the ammonia feedstock stream into said effluent gas
Implementation Method 4
During the conversion step, no additional heat is supplied to the heated gas stream such that the temperature of said gas stream gradually decreases alongside the adiabatic reactor
Data Source
Figure 1
AI summary
The invention relates to a process for the production of hydrogen gas (4) from ammonia, thereby obtaining an effluent gas (6) comprising hydrogen gas (4). Said process comprising the following steps: - providing an ammonia feedstock stream (8); - performing at least one electrical heating and conversion step, said step comprising: heating in at least one electric heater (12) the ammonia feedstock stream (8) so as to produce a heated gas stream (14); and performing in at least one adiabatic reactor (16) an endothermic cracking reaction of the heated gas stream (14), said adiabatic reactor (16) comprising at least one catalyst bed (18) performing said endothermic cracking reaction of the ammonia feedstock stream (8) into said effluent gas (6).