Fixed-Bed Catalyst Regeneration Using Regenerative Thermal Oxidizer Gas
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Solution Overview
Problem
Existing methods for regenerating catalysts in fixed bed reactors used for producing acrylic acid from lactic acid are costly and can cause thermal shock due to the use of inert gases like nitrogen, leading to increased costs and catalyst deactivation.
Innovation Solution
A method and apparatus that utilize a regenerative thermal oxidizer to combust by-products from the acrylic acid production process, using the discharged gas for catalyst regeneration, thereby reducing costs and minimizing thermal shock.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If inert gases like nitrogen are used for catalyst regeneration, then the catalyst can be regenerated, but thermal shock occurs leading to catalyst deactivation and increased costs
Solution Approach 1:
The patent changes the temperature parameter profile during catalyst regeneration by introducing a gradual heating phase before the main combustion phase. The regenerative thermal oxidizer first heats the catalyst bed to a moderate temperature (e.g., 200-400°C) over an extended period, then gradually increases to higher temperatures for coke combustion. This controlled parameter change prevents thermal shock while ensuring effective regeneration.
Solution Approach 2:
The patent applies preliminary action by pre-heating the catalyst bed and establishing a controlled atmosphere before initiating full-scale combustion. The regenerative thermal oxidizer first introduces a controlled amount of oxygen and gradually builds up the combustion reaction, rather than introducing high-temperature combustion directly. This preliminary preparation prevents thermal shock to the catalyst structure.
2Reliability
If conventional catalyst regeneration methods are used, then catalyst activity can be restored, but process costs increase due to inert gas consumption
Solution Approach 1:
The patent implements self-service by using the waste heat generated during the combustion phase to preheat the incoming feed gas and maintain the catalyst bed temperature. The regenerative thermal oxidizer contains heat storage media that absorb excess heat during combustion and release it during the regeneration phase, eliminating the need for external heating energy and inert gas consumption. The system essentially uses itself to provide the necessary thermal energy for regeneration.
Solution Approach 2:
The patent recovers and reuses the waste heat and oxygen-containing flue gas from the combustion process. Instead of discarding the hot exhaust gas from the thermal oxidizer, it is redirected to contact with the spent catalyst and used for regeneration. This recovery approach eliminates the need for separate heating systems and inert gas consumption, significantly reducing process costs while maintaining effective catalyst regeneration.
3Productivity
If high temperatures are applied for catalyst regeneration, then coke removal is effective, but catalyst deactivation occurs due to thermal damage
Solution Approach 1:
The patent applies periodic action by alternating between combustion phases (high temperature for coke removal) and cooling/maintenance phases (lower temperature for catalyst protection). The regenerative thermal oxidizer operates in cycles, introducing oxygen for a controlled period to burn off coke, then reducing or stopping oxygen supply to allow the catalyst to cool and stabilize. This periodic operation ensures effective coke removal while preventing thermal damage through repeated cooling intervals.
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 method enables stable and cost-effective catalyst regeneration by using waste gases for regeneration, reducing process costs and maintaining catalyst integrity.
Implementation Method 1
a regenerative thermal oxidizer that combusts the by-product discharged from an upper part of the separator
Implementation Method 2
a heat exchanger that cools the gas discharged from the regenerative thermal oxidizer and supplies it to the second reactor
Implementation Method 3
supplying a feed containing lactic acid gas to a first reactor filled with a catalyst to progress a lactic acid dehydration reaction
Data Source
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AI summary
The present disclosure relates to a method and apparatus for regeneration of fixed bed catalytic reactor, and more particularly, to a method and apparatus for regeneration of a catalyst in the process of producing acrylic acid from lactic acid.