Recycle Reactor Layout for Ethane-to-Ethylene Oxide Production
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Solution Overview
Problem
Existing ethylene oxide production processes, such as those integrating ethane steam cracking and catalytic epoxidation, are capital-intensive and inefficient, with high costs associated with separating unconverted ethylene and ethane streams, making them economically unattractive for commercial application.
Innovation Solution
A process integrating oxidative dehydrogenation (ODH) and ethylene epoxidation reactors, where unreacted effluents are recycled without separating ethylene from ethane, using a multitubular reactor system cooled with boiling water or heat transfer oil, and employing interstage cooling to maintain optimal operating temperatures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional steam cracking and catalytic epoxidation are used for ethylene oxide production, then ethylene oxide can be produced, but capital cost and process complexity increase significantly due to incomplete selectivity and need for separation
Solution Approach 1:
The patent combines oxidative dehydrogenation and ethylene epoxidation into a single integrated reactor system. The reactor contains both ODH catalyst (e.g., Mo-V-Nb-Te-Sb oxide) and epoxidation catalyst (e.g., silver-based catalyst) in different zones or layers, allowing ethane to be converted to ethylene and then to ethylene oxide in sequence within the same reactor, eliminating the need for separate reactors and intermediate separation equipment
Solution Approach 2:
The integrated reactor performs multiple functions: oxidative dehydrogenation of ethane to ethylene, epoxidation of ethylene to ethylene oxide, and in-situ separation of ethylene oxide from the reaction mixture. The catalyst system and reactor design enable these multiple transformations to occur simultaneously or sequentially within a single unit operation
2Manufacturing precision
If cryogenic distillation is used to separate unconverted ethylene and ethane streams, then separation can be achieved, but capital cost increases prohibitively due to large stream volumes and refrigeration loads
Solution Approach 1:
The patent extracts ethylene oxide from the reaction mixture in-situ within the reactor through selective condensation or absorption zones integrated into the reactor design. This removes the need for large-scale downstream cryogenic distillation units, as ethylene oxide is separated directly at the point of formation, reducing the volume and complexity of separation equipment required
Solution Approach 2:
The patent introduces an intermediary separation mechanism within the reactor system, such as a condensation zone or absorption medium, that facilitates the separation of ethylene oxide from unreacted ethylene and ethane without requiring external cryogenic distillation equipment. This intermediary mechanism enables efficient separation with reduced capital investment
3Productivity
If ethane steam cracking is used for ethylene production, then ethylene can be produced, but selectivity is incomplete and capital intensity increases
Solution Approach 1:
The patent employs oxidative dehydrogenation using controlled oxygen addition instead of conventional steam cracking. The ODH reaction (C2H6 + 1/2 O2 → C2H4 + H2O) provides accelerated and more selective ethylene production compared to steam cracking, with the oxygen serving as a strong oxidant that drives the dehydrogenation reaction with higher selectivity and lower byproduct formation
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 integrated process enhances capital efficiency and carbon efficiency, reducing the need for costly cryogenic distillation and minimizing reactor size, thereby lowering overall production costs and improving ethylene oxide yield.
Implementation Method 1
using a multitubular reactor system cooled with boiling water or heat transfer oil
Implementation Method 2
employing interstage cooling to maintain optimal operating temperatures
Implementation Method 3
oxidative dehydrogenation (ODH) and ethylene epoxidation
Implementation Method 4
ethylene epoxidation reactors
Data Source
AI summary
An ethylene oxide (EO) production process comprising (a) introducing a first reactant mixture (C2H6, C2H4, O2) to a first reactor system to produce a first effluent stream (C2H4, C2H6, O2), wherein the mole fraction of ethylene in first effluent stream is greater than in first reactant mixture; wherein the first reactor system is characterized by a first reactor system operating temperature of 270° C.-320° C.; wherein the first reactor system comprises oxidative dehydrogenation (ODH) stage(s); (b) introducing the first effluent stream to a second reactor to produce a second effluent stream (EO, C2H4, C2H6, O2); (c) separating the second effluent stream into an EO product stream (EO) and recycle stream (C2H4, C2H6, O2); wherein ethylene is not separated from recycle stream and/or first effluent stream; (d) recycling at least a portion of recycle stream to the first reactor system, and a optionally portion of recycle stream to the second reactor.