Integrated Ethane ODH–Epoxidation Process With Split Recycle
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Solution Overview
Problem
Conventional ethylene oxide production processes, such as those using ethane steam cracking and catalytic epoxidation, are capital-intensive and inefficient, with high costs associated with separating unconverted ethylene and ethane streams, making the integration of oxidative dehydrogenation and ethylene epoxidation technologies economically unviable.
Innovation Solution
A process integrating oxidative dehydrogenation and ethylene epoxidation reactors with a recycle configuration that eliminates the need for ethylene-ethane separation, allowing for the direct recycling of unreacted effluents between reactors and incorporating oxygen make-up streams to maintain process efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If conventional ethane steam cracking and catalytic epoxidation are used for ethylene oxide production, then ethylene oxide can be produced, but the process becomes capital-intensive with high costs associated with separating unconverted ethylene and ethane streams
Solution Approach 1:
The patent combines oxidative dehydrogenation and ethylene epoxidation into a single integrated process sequence, eliminating the need for separate ethylene-ethane separation units. The effluent from the ODH reactor is directly fed to the EO reactor, merging two previously separate processes into one continuous flow system that reduces capital intensity while maintaining productivity.
Solution Approach 2:
The patent extracts and eliminates the costly cryogenic distillation separation step from the conventional process. By using a recycle configuration where unreacted ethylene and ethane are recycled directly between reactors without separation, the process removes the capital-intensive separation equipment while preserving the necessary chemical conversions.
2Measurement precision
If cryogenic distillation is used to separate ethylene and ethane in the recycle stream, then separation efficiency is improved, but refrigeration loads and distillation tower sizes become prohibitively expensive
Solution Approach 1:
The patent removes the cryogenic distillation separation step entirely from the process. Instead of separating ethylene from ethane, the system recycles the mixed stream directly from the EO reactor back to the ODH reactor, eliminating the need for expensive refrigeration and distillation towers while maintaining process efficiency.
Solution Approach 2:
The patent uses a recycle configuration that copies the unreacted materials back through the reaction sequence rather than separating and purifying them. This recycling approach replicates the functional need for pure reactants without requiring the capital-intensive separation infrastructure.
3Productivity
If unconverted ethylene and ethane are separated and recycled to respective reactors, then reaction efficiency is improved, but the large stream volume requires costly separation equipment
Solution Approach 1:
The patent merges the recycle streams of ethylene and ethane into a single mixed stream that is recycled together from the EO reactor back to the ODH reactor. This consolidation eliminates the need for separate recycle streams and separation equipment, reducing device complexity while maintaining reaction efficiency through continuous circulation.
Solution Approach 2:
The recycle stream serves multiple functions simultaneously: it returns unreacted ethylene for further conversion, returns unreacted ethane for continued oxidation, and maintains process continuity without requiring separation. This multi-functional recycle approach eliminates the need for dedicated separation equipment.
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 enhances carbon efficiency and reduces capital intensity by eliminating costly cryogenic distillation, achieving higher overall efficiency and lower capital costs in ethylene oxide production.
Implementation Method 1
a first catalytic reactor (e.g., oxidative dehydrogenation (ODH) reactor) for converting ethane to ethylene by ODH
Implementation Method 2
a second catalytic reactor (e.g., EO reactor) for converting ethylene to EO
Data Source
AI summary
An ethylene oxide (EO) production process comprising (a) introducing a first reactant mixture (C2H6, O2) to a first reactor to produce a first effluent stream (C2H4, C2H6, O2); (b) introducing a second reactant mixture to a second reactor to produce a second effluent stream (EO, C2H4, C2H6, O2); wherein the second reactant mixture comprises at least a portion of first effluent stream; (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; and (d) recycling a first portion of recycle stream to the first reactor, and a second portion of recycle stream to the second reactor; wherein recycle split ratio <0.6; and wherein recycle split ratio is defined as ratio of volumetric flowrate of first portion of recycle stream divided by the sum of volumetric flowrates of first portion and second portion of recycle stream.