CLC Process Dual Oxidation Zones High Purity Nitrogen
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Solution Overview
Problem
The existing Chemical Looping Combustion (CLC) processes struggle to produce high purity nitrogen when total combustion of hydrocarbon feeds is desired, as they require excess air, leading to residual oxygen in the nitrogen stream, which is not suitable for applications requiring low oxygen levels, such as enhanced oil recovery or refinery processes.
Innovation Solution
A CLC process with two oxidation zones is implemented, where the reduced redox active mass is first oxidized with a depleted oxygen stream to produce a stream of dinitrogen with low dioxygen content, and then further oxidized with air to produce a depleted air stream, which is divided to recycle a fraction back to the first oxidation zone, allowing for the production of high purity nitrogen with less than 10 ppmv of dioxygen.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If excess air is used to ensure complete re-oxidation of particles in the air reactor, then the oxidation of active mass is improved, but the nitrogen purity of the effluent deteriorates due to residual oxygen
Solution Approach 1:
The air reactor is divided into two separate reactors: a first air reactor that produces nitrogen-rich effluent with controlled oxygen content, and a second air reactor that completes the oxidation using the nitrogen-rich stream from the first reactor. This segmentation allows each reactor to be optimized for its specific function, resolving the contradiction between complete oxidation and nitrogen purity.
Solution Approach 2:
The nitrogen-rich effluent from the first air reactor serves as an intermediary medium for the oxidation process in the second air reactor. Instead of using pure air in both reactors, the first reactor's output becomes the oxidizing medium for the second reactor, enabling controlled oxygen transfer while maintaining high nitrogen purity in the final effluent.
2Device complexity
If a single air reactor is used for oxidation, then the device complexity is reduced, but the ability to produce high purity nitrogen deteriorates
Solution Approach 1:
The single air reactor is segmented into two distinct air reactors with different functions. The first reactor is optimized for producing nitrogen-rich effluent, while the second reactor completes the oxidation process. This segmentation increases device complexity but enables the production of high purity nitrogen that cannot be achieved with a single reactor.
Solution Approach 2:
The nitrogen-rich effluent from the first air reactor serves multiple purposes: it is the desired product stream and simultaneously serves as the oxidizing medium for the second air reactor. This multi-functionality allows the system to achieve high nitrogen purity while maintaining complete oxidation of the active mass.
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 effectively reduces the oxygen content in the nitrogen stream to meet stringent purity requirements, minimizing the need for additional purification steps and reducing energy and investment costs, while maintaining efficient operation and high nitrogen production yields.
Implementation Method 1
Chemical Looping Combustion (CLC) is a process consisting of carrying out redox reactions on an active mass, typically a metal oxide, to break up the combustion reaction into two successive reactions
Implementation Method 2
carrying out redox reactions on an active mass, typically a metal oxide, to break up the combustion reaction into two successive reactions: a first reaction for oxidation of the active mass in contact with an oxidizing gas, typically air, and a second reaction for reduction of the active mass in contact with the feed
Implementation Method 3
The stream of depleted air is divided into a first fraction and a second fraction. The first fraction is brought into contact with the reduced redox active mass in the first oxidation zone in order to produce a stream of dinitrogen
Data Source
AI summary
The invention concerns a CLC process, and its installation, producing high purity dinitrogen, comprising:(a) the combustion of a hydrocarbon feed by reduction of a redox active mass brought into contact with the feed,(b) a first step for oxidation of the reduced active mass (25) obtained from step (a) in contact with a fraction of a depleted air stream (21b), in order to produce a high purity stream of dinitrogen (28) and a stream of partially re-oxidized active mass (26);(c) a second step for oxidation of the stream of active mass (26) in contact with air (20) in order to produce a stream of depleted air and a stream of re-oxidized active mass (24) for use in step (a);(d) dividing the stream of depleted air obtained at the end of step (c) in order to form the fraction of depleted air used in step (b) and a fraction complementary to the depleted air extracted from the CLC.