Two-Zone Ethane ODH Process for Unconverted Oxygen Control
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Solution Overview
Problem
Existing ethane oxidative dehydrogenation processes face challenges in managing unconverted oxygen in the effluent, which poses explosion hazards and requires cumbersome additional steps for carbon monoxide and acetylene removal, coupled with the production of carbon dioxide, leading to inefficiencies and high capital expenditure.
Innovation Solution
A two-zone oxidative dehydrogenation process using mixed metal oxide catalysts, where ethane and oxygen are supplied to a first zone, and the effluent is mixed to uniformly distribute unconverted oxygen before being fed to a second zone for further conversion, decoupling the removal of unconverted oxygen from carbon monoxide and acetylene.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If more oxygen is fed to the ODH reactor to avoid oxygen depletion conditions, then the risk of operating at oxygen depletion conditions is reduced, but unconverted oxygen in the effluent increases the risk of explosion hazards
Solution Approach 1:
The patent extracts and removes unconverted oxygen from the ODH effluent through a dedicated oxygen removal step before the back-end separation section. This eliminates the harmful effect of unconverted oxygen while allowing the reactor to operate with excess oxygen to avoid depletion conditions.
2Object-affected harmful factors
If a separate oxygen removal step is added to remove unconverted oxygen, then explosion hazards are reduced, but the process complexity and capital expenditure increase
Solution Approach 1:
The patent combines the oxygen removal function with the existing back-end separation section by integrating it as a preprocessing step. The oxygen removal unit operation is merged into the overall separation train, allowing shared infrastructure and reducing the need for completely separate systems.
Solution Approach 2:
The oxygen removal step is designed to serve multiple purposes: removing unconverted oxygen to prevent explosion hazards, preparing the effluent for subsequent separation operations, and potentially removing other contaminants. This multi-functionality justifies the added complexity by providing multiple benefits from a single unit operation.
3Object-affected harmful factors
If unconverted oxygen is removed before the back-end separation section, then explosion hazards are reduced, but additional energy demand is incurred
Solution Approach 1:
The oxygen removal step is performed preliminarily, before the back-end separation section, to eliminate unconverted oxygen early in the process. This preliminary action prevents downstream explosion hazards and may reduce the energy demand of subsequent separation operations by simplifying the composition of the effluent entering the separation section.
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 eliminates the need for separate oxygen removal steps, optimizes reaction conditions, reduces energy demand, and enhances catalyst stability, while minimizing capital expenditure and improving ethylene yield.
Implementation Method 1
contacting the ethane and oxygen with the catalyst in the multiple reactor tubes in the first oxidative dehydrogenation zone resulting in multiple effluent streams
Implementation Method 2
the multiple reactor tubes are cooled by a coolant
Implementation Method 3
mixing at least a portion of the multiple effluent streams from step b) resulting in a mixture comprising ethylene, unconverted ethane and unconverted oxygen
Implementation Method 4
contacting at least a portion of the mixture from step c) with the catalyst in the second oxidative dehydrogenation zone resulting in a stream comprising ethylene and unconverted ethane
Data Source
AI summary
The invention relates to a process for the production of ethylene by oxidative dehydrogenation (ODH) of ethane, comprising: a) supplying ethane and oxygen to a first ODH zone which is formed by multiple reactor tubes containing a mixed metal oxide ODH catalyst bed; b) contacting the ethane and oxygen with the catalyst resulting in multiple effluent streams, wherein the multiple reactor tubes are cooled by a coolant; c) mixing at least a portion of the multiple effluent streams from step b) resulting in a mixture comprising ethylene, unconverted ethane and unconverted oxygen; d) supplying at least a portion of the mixture from step c) to a second ODH zone containing a mixed metal oxide ODH catalyst bed; e) contacting at least a portion of the mixture from step c) with the catalyst in the second ODH zone resulting in a stream comprising ethylene and unconverted ethane.