Microchannel Reactor Catalyst Regeneration via Controlled Temperature Transitions
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Solution Overview
Problem
The Fischer-Tropsch catalyst degrades over time, requiring regeneration to maintain effectiveness, especially in microchannel reactors, where in situ regeneration is challenging due to potential equipment damage from water hammering and prolonged cooling/heating processes.
Innovation Solution
A process for in situ catalyst regeneration in microchannel reactors involving de-waxing, oxidation, and reduction steps, with controlled temperature transitions using heat exchange fluids like steam, minimizing phase changes and reducing regeneration time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the catalyst is cooled to low temperature (e.g., 70°C) to prevent water hammering during phase change, then equipment safety is improved, but the regeneration time is significantly prolonged
Solution Approach 1:
The patent changes the temperature parameter from conventional low temperature (70°C) to elevated temperature (150-200°C) during the transition phase between de-waxing and oxidation steps. This parameter change allows the heat exchange fluid to remain in liquid phase without causing water hammering, thereby avoiding the need for prolonged cooling while maintaining equipment safety.
Solution Approach 2:
The patent performs preliminary cooling to an elevated temperature (150-200°C) before introducing the oxidizing gas stream. This preliminary action prepares the system in a safe state (above dew point) that prevents water hammering, allowing subsequent oxidation to proceed without requiring additional cooling time.
2Object-affected harmful factors
If the catalyst is cooled to low temperature to avoid water hammering from phase change, then equipment damage risk is reduced, but production downtime increases
Solution Approach 1:
The patent changes the temperature parameter from conventional low temperature (70°C) to elevated temperature (150-200°C) during the transition phase. This keeps the heat exchange fluid in liquid phase, eliminating water hammering risk while significantly reducing the time required for temperature transitions and thereby minimizing production downtime.
Solution Approach 2:
The patent converts the potential harm of elevated temperature (which could cause water hammering) into a benefit by carefully controlling the temperature to be above the dew point but below temperatures that would cause uncontrolled oxidation. This allows the system to operate in a regime that prevents water hammering while maintaining short regeneration times.
3Loss of time
If the temperature is rapidly increased to oxidation temperature after de-waxing, then regeneration time is reduced, but water hammering may occur causing equipment damage
Solution Approach 1:
The patent changes the temperature parameter from low temperature (70°C) to elevated temperature (150-200°C) during the transition phase. This allows rapid temperature increase without water hammering because the heat exchange fluid remains in liquid phase, thus achieving both fast regeneration and equipment safety.
Solution Approach 2:
The patent uses an intermediary temperature state (150-200°C) that serves as a bridge between de-waxing temperature and oxidation temperature. This intermediary state prevents water hammering while enabling efficient transition to oxidation conditions, acting as a mediator that reconciles the conflicting requirements of speed and safety.
4Productivity
If the catalyst is maintained at high temperature during oxidation, then oxidation effectiveness is improved, but the risk of uncontrolled exothermic reaction increases
Solution Approach 1:
The patent changes the temperature parameter from conventional low temperature to elevated temperature (150-200°C) during the transition phase. This allows the system to reach oxidation temperature more quickly while maintaining control, improving oxidation effectiveness without causing uncontrolled reactions.
Solution Approach 2:
The patent implements feedback control by monitoring temperature and adjusting the oxidizing gas flow rate accordingly. The oxidizing gas is introduced at a controlled rate that maintains temperature within the safe range (150-200°C during transition, then elevated for oxidation), preventing uncontrolled exothermic reactions while ensuring effective oxidation.
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 process effectively regenerates the catalyst, reducing downtime and equipment risk, while maintaining catalyst activity and efficiency, and allowing for continuous production without significant plant downtime.
Implementation Method 1
the temperature inside the process microchannels and/or the heat exchange channels is lowered from a temperature sufficient for de-waxing to a first lower limit value of 90° C. or greater... the temperature inside the process microchannels and/or the heat exchange channels being controlled by heat exchange fluid flowing through the heat exchange channels
Implementation Method 2
b) oxidising the resulting de-waxed catalyst by treating it at an elevated temperature with an oxidising gas stream flowing through process microchannels of the reactor
Implementation Method 3
c) reducing the resulting oxidised catalyst by treating it at an elevated temperature with a reducing gas stream flowing through process microchannels of the reactor
Data Source
AI summary
A catalyst is regenerated by an inventive process using a heat exchange fluid such as superheated steam to remove heat during the process relying on efficient heat transfer (e.g., enabled by the microchannel reactor construction) in comparison with prior art heat exchange relying on a phase change, e.g. between water and (partial or complete vaporization) steam, allows simplification of the protocols to enable transition at higher temperatures between steps which translates in reduced duration of the regeneration process and avoids potential water hammering risks.