ODH complex with on-line mixer unit and feed line cleaning
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Solution Overview
Problem
Oxidative dehydrogenation (ODH) of lower alkanes into corresponding alkenes faces challenges with energy intensity, high costs, coke production, and selectivity limitations in existing methods, particularly due to the hazardous mixing of oxygen with hydrocarbons, which poses safety risks and efficiency issues.
Innovation Solution
A chemical complex comprising two upstream gas mixer units for premixing oxygen and lower alkane gases, connected in parallel to an ODH reactor, with a cleaning loop for sulfur removal, ensuring safe and efficient mixing and operation, and utilizing a solvent like dimethyl disulfide (DMDS) to dissolve sulfur deposits without affecting the ODH process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If oxygen and hydrocarbon are mixed directly, then the ODH reaction can proceed, but safety risks increase due to potential catastrophic mixing
Solution Approach 1:
The mixing process is divided into multiple stages: first mixing oxygen with inert gas (nitrogen or CO2) to create a safe oxygen-containing gas mixture, then separately mixing hydrocarbon with inert gas, and finally combining these two streams. This segmentation prevents direct catastrophic mixing of pure oxygen and hydrocarbon while maintaining ODH reaction efficiency.
Solution Approach 2:
Inert gas (nitrogen or CO2) serves as an intermediary substance that mediates between oxygen and hydrocarbon. The inert gas dilutes both oxygen and hydrocarbon streams, creating a buffer that prevents direct hazardous interaction while enabling the ODH reaction to proceed through controlled intermediate mixing stages.
2Ease of manufacture
If steam cracking is used to produce alkenes, then the process is well-established, but energy consumption increases due to high temperature requirements
Solution Approach 1:
The invention changes the temperature parameter from the high temperatures (700-1000°C) required for steam cracking to lower temperatures (300-500°C) suitable for ODH reaction. This parameter change is achieved by using ODH catalysts and controlled oxygen-containing gas mixing, reducing energy consumption while maintaining process viability through the two-stage mixing approach.
3Productivity
If ODH operates with direct oxygen-hydrocarbon mixing, then selectivity for alkenes improves, but harmful factors increase due to safety risks
Solution Approach 1:
The mixing operation is segmented into two separate mixing units: first mixing unit combines oxygen with inert gas, second mixing unit combines hydrocarbon with inert gas. This segmentation allows high selectivity ODH reaction to proceed while eliminating safety hazards of direct oxygen-hydrocarbon mixing through controlled intermediate steps.
Solution Approach 2:
Inert gas acts as an intermediary that enables high alkene selectivity by facilitating controlled oxygen transfer to hydrocarbon through the ODH catalyst, while simultaneously preventing safety hazards by diluting reactant concentrations and preventing direct catastrophic mixing.
4Device complexity
If a single mixer unit is used, then device complexity is reduced, but reliability decreases due to lack of redundancy
Solution Approach 1:
The two mixing units have different local qualities/functions: first mixer handles oxygen-inert gas mixing, second mixer handles hydrocarbon-inert gas mixing. This functional differentiation enables reliability through redundancy while managing complexity by assigning specific roles to each unit, allowing one unit to be maintained while the other operates.
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
The solution enhances the safety and efficiency of ODH by reducing energy consumption, minimizing coke production, and achieving high selectivity for alkenes while safely managing the mixing of oxygen and hydrocarbons, and effectively removing sulfur deposits, thus improving process reliability and product yield.
Implementation Method 1
an oxidative dehydrogenation catalyst contained within the at least one oxidative dehydrogenation reactor reacts with the mixed feed stock stream to produce a product stream comprising the corresponding alkene
Implementation Method 2
introducing cleaning solvent into the isolated mixer and cycling cleaning solvent through a cleaning loop until the sulfur-containing deposits are removed
Data Source
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AI summary
Oxidative dehydrogenation is an alternative to the energy extensive steam cracking process presently used for the production of olefins from paraffins. Various embodiments of an oxidative dehydrogenation chemical complex designed to allow removal of sulfur containing contaminants that collect in the gas mixer unit and in the feed lines leading to the ODH reactor are disclosed herein.