Ceramic Honeycomb Ammonia Cracker With Uniform Joule Heating
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Solution Overview
Problem
The ammonia decomposition apparatus in Patent Literature 1 faces issues with non-uniform temperature distribution in the metallic honeycomb structure, leading to a trade-off between improved ammonia conversion and catalyst life, as high temperatures enhance conversion but reduce catalyst longevity, while low temperatures maintain catalyst life but decrease conversion.
Innovation Solution
An ammonia decomposition apparatus utilizing a ceramic honeycomb structure with a catalyst layer and electrodes on its lateral surface, where a current is applied to achieve uniform heating through the conductive honeycomb structure made of silicon carbide and silicon nitride, allowing for a catalyst-supporting honeycomb structure with a catalyst layer in the flow channel.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the reaction temperature is raised to improve ammonia conversion, then the conversion of ammonia is improved, but the life of the catalyst is shortened by growth or the like of fine particles of the catalyst
Solution Approach 1:
The patent applies local quality by creating different temperature zones within the honeycomb structure through non-uniform heating. The heater contacts only the upstream side, creating a temperature gradient where the upstream region operates at higher temperatures for improved ammonia conversion while the downstream region operates at lower temperatures to preserve catalyst life. This spatial differentiation of thermal conditions allows simultaneous optimization of both conversion and catalyst longevity in different locations.
2Use of energy by stationary object
If a metallic honeycomb structure is heated by contacting a heater with the upstream side, then heat is supplied for decomposition, but the temperature distribution of the honeycomb structure cannot be made uniform
Solution Approach 1:
The patent segments the heating function by providing multiple heaters that contact different regions of the honeycomb structure. Instead of a single heater causing non-uniform heating, multiple heaters are strategically positioned to distribute heat more evenly across the structure. This segmentation of the heating source enables uniform temperature distribution while maintaining the necessary thermal energy for ammonia decomposition throughout the catalyst bed.
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 apparatus achieves both improved ammonia conversion and extended catalyst life by ensuring uniform heating of the honeycomb structure, thereby optimizing the decomposition process.
Implementation Method 1
a current is applied to the honeycomb structure
Implementation Method 2
a catalyst layer that is formed in a flow channel of the honeycomb structure and decomposes ammonia
Implementation Method 3
The decomposition reaction of ammonia is an endothermic reaction
Data Source
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AI summary
Provided is an ammonia decomposition apparatus capable of achieving both an improved conversion of ammonia and an improved life of a catalyst. An ammonia decomposition apparatus (11) includes an ammonia gas inlet (13), a catalyst-supporting honeycomb structure (1) that decomposes ammonia to produce hydrogen and nitrogen, and a gas outlet (14). The catalyst-supporting honeycomb structure (1) includes a ceramic honeycomb structure, a catalyst layer 3 formed in a flow channel (2a) of the honeycomb structure and decomposes ammonia, and a pair of electrodes (4a and 4b) formed on lateral surfaces of the honeycomb structure. A current is applied to the honeycomb structure.