Membrane Separation for Oxidative Dehydrogenation
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Solution Overview
Problem
Conventional oxidative dehydrogenation processes for paraffins require costly air separation equipment and complex nitrogen separation from hydrogen-rich product streams, leading to uneconomical operations and catalyst deactivation due to the use of paraffins as diluents.
Innovation Solution
A process utilizing membrane separation units to efficiently separate nitrogen from hydrogen-rich product streams, allowing for the recycling of hydrogen and eliminating the need for expensive air separation equipment, while also incorporating a chloride treater and acid gas treater to further optimize the dehydrogenation process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If air is used instead of pure oxygen to partially combust hydrogen, then the mixture remains outside explosive limits due to nitrogen dilution, but nitrogen separation from hydrogen-rich product stream becomes complex and costly
Solution Approach 1:
The patent extracts and removes nitrogen from the hydrogen-rich product stream using a membrane separation unit. The membrane selectively permeates hydrogen while retaining nitrogen, effectively separating the two gases and eliminating the need for complex conventional separation equipment
Solution Approach 2:
The patent changes the physical state and pressure parameters of the gas stream by compressing it before membrane separation. This parameter change optimizes the membrane separation process, enabling efficient nitrogen removal while maintaining hydrogen recovery
2Manufacturing precision
If conventional separation techniques are used to separate nitrogen from hydrogen, then separation is achieved, but additional equipment like compressors is required which substantially increases operating costs
Solution Approach 1:
The patent replaces complex mechanical separation systems (compressors, distillation columns) with a membrane separation unit that utilizes selective permeability. This substitution dramatically reduces mechanical complexity and operating energy requirements while maintaining effective nitrogen removal
Solution Approach 2:
The patent employs a membrane separation unit with thin film structures that selectively allow hydrogen to pass through while blocking nitrogen. This thin film technology achieves separation with minimal energy input compared to conventional mechanical separation equipment
3Reliability
If paraffin is added as diluent for dehydrogenation, then the reaction proceeds safely, but additional external heating or oxygen is required making the process uneconomical
Solution Approach 1:
The patent recycles the separated hydrogen back to the dehydrogenation reactor, where it serves as both a reactant and a heat carrier. This recovery and reuse of hydrogen eliminates the need for external heating and additional oxygen, making the process economically viable
Solution Approach 2:
The process becomes self-sufficient by using the produced hydrogen to maintain reaction conditions. The recycled hydrogen provides both the chemical reactant and the thermal energy needed for continuous dehydrogenation without external heating inputs
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 improves process economics by reducing equipment costs and enabling hydrogen recycling, thereby extending catalyst life and enhancing dehydrogenation efficiency.
Implementation Method 1
The compressed process stream is passed to a membrane separation unit to generate a hydrogen rich stream and a process stream with reduced hydrogen content
Implementation Method 2
The process stream with reduced water content is passed to a compressor to generate a compressed process stream
Implementation Method 3
The cleaned paraffin stream is passed to an oxidative dehydrogenation reactor. A fuel stream is passed to the oxidative dehydrogenation reactor. A heated air stream is passed to the oxidative dehydrogenation reactor, wherein the air, fuel and paraffin are reacted to generate a process stream comprising olefins
Data Source
AI summary
A process is presented for the dehydrogenation of paraffins. The process utilizes heated air for the combustion of a fuel within the dehydrogenation reactor to provide the heat of reaction for oxidative dehydrogenation. The nitrogen in the air is utilized as a diluent. A paraffin feedstream is mixed with a fuel, and the fuel/paraffin feedstream is mixed with an oxidant air stream at the inlet of dehydrogenation reactor.