Nitrous Oxide Decomposition via Segmented Reactor System
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The existing processes for decomposing nitrous oxide from off-gas streams in adipic acid production are inefficient due to catalyst aging, leading to reduced decomposition efficiency and increased greenhouse gas emissions.
Innovation Solution
A process involving the splitting of the gas stream into multiple partial streams, each heated separately and fed into separate decomposition reactors with catalysts. The catalysts are alternately changed based on their mean lifetime, optimizing the decomposition reaction temperatures and maintaining process efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the gas stream is fed into a single decomposition reactor with one catalyst, then the process is simple to operate, but the decomposition efficiency decreases over time due to catalyst aging
Solution Approach 1:
The gas stream is split into multiple partial streams that are fed into separate decomposition reactors, each containing its own catalyst. This segmentation allows independent operation and maintenance of each reactor, preventing complete process shutdown when one catalyst needs replacement while maintaining overall decomposition efficiency.
Solution Approach 2:
Multiple decomposition reactors are combined in parallel to form a unified decomposition system. The reactors work simultaneously to process different portions of the gas stream, providing redundancy and continuous operation capability while maintaining high decomposition efficiency overall.
2Productivity
If the catalyst is used for a long time without replacement, then the process operates continuously, but the decomposition efficiency reduces due to catalyst aging
Solution Approach 1:
The catalyst system is segmented into multiple independent catalysts in separate reactors. This allows individual catalysts to be replaced at different times based on their aging rates, enabling continuous operation of the overall system while maintaining high decomposition efficiency in the active reactors.
Solution Approach 2:
Catalysts are replaced periodically in a rotating fashion across the multiple reactors. While one catalyst is being replaced, others continue to operate, creating a periodic maintenance schedule that maintains continuous productivity while refreshing catalyst efficiency regularly.
3Productivity
If the inlet temperature is increased to maintain decomposition efficiency with aged catalyst, then the decomposition rate improves, but the risk of catalyst sintering increases
Solution Approach 1:
The temperature management is segmented across multiple reactors with different catalyst ages. Fresh catalysts can operate at lower temperatures while maintaining high efficiency, whereas aged catalysts in other reactors can be replaced without affecting overall decomposition rate, avoiding the need to consistently operate at high temperatures that risk sintering.
Solution Approach 2:
The system dynamically adjusts operating parameters based on catalyst age. As catalysts age, their replacement is scheduled rather than increasing temperature, maintaining decomposition efficiency through parameter management (catalyst selection) rather than temperature increases that would risk sintering.
4Reliability
If multiple decomposition reactors are used with alternating catalyst replacement, then the temporal availability is enhanced, but the device complexity increases
Solution Approach 1:
The reactor system is segmented into multiple independent units that can operate autonomously. This segmentation enables maintenance of one unit without shutting down others, enhancing temporal availability while keeping each individual reactor simple in design.
Solution Approach 2:
The multiple reactors are designed as universal, identical units that can interchangeably perform the same decomposition function. This universality simplifies the overall system architecture compared to having complex specialized reactors, as each unit is a standardized module that can be maintained independently.
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 significantly improves the overall efficiency of nitrous oxide decomposition, reduces the amount of remaining nitrous oxide in the off-gas, and enhances the temporal availability of the process by minimizing the impact of catalyst aging.
Implementation Method 1
the decomposition of nitrous oxide into nitrogen and oxygen is carried out in the presence of a catalyst, particularly a fixed bed catalyst
Implementation Method 2
a regenerative heater and an additional heater which is used for controlling the inlet temperature of the off-gas into the reactor
Implementation Method 3
the highly exothermic behavior of this reaction. Each percent of nitrous oxide in the off-gas stream creates an adiabatic temperature increase of 25°C
Data Source
Figure 1~2
AI summary
The invention relates to a process for decomposing nitrous oxide from a gas stream (1), com- prising: (a) heating the gas stream (1) and splitting the gas stream (1) into at least two partial streams (3, 5) or splitting the gas stream (1) into at least two partial streams (3, 5) and heating the partial streams (3, 5); (b) feeding each of the partial streams (3, 5) into a separate decomposition reactor, wherein each reactor (31) comprises a catalyst; (c) decomposing the nitrous oxide into nitrogen and oxygen in the decomposition reactors to obtain purified streams (13, 15); (d) optionally feeding each purified stream (13, 15) into a unit (11) for decomposing nitrogen dioxide and/or nitrogen monoxide or combining at least two purified streams (13, 15) and feeding the combined purifed streams into a unit (11) for decomposing nitrogen dioxide and/or nitrogen monoxide, wherein the catalysts of the decomposition reactors (31) are changed alternatingly and wherein one of the catalysts is changed when the arithmetic mean of the lifetime of the catalysts in the other reactors has reached 25 to 75 % of the lifetime of one catalyst.