Partial Burn Combustor Regenerator Oxygen Control
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Solution Overview
Problem
Conventional combustor regenerators have not been operated in partial burn mode due to the risk of after burn, which occurs when excess oxygen from fluidization air combusts carbon monoxide in the dilute phase, leading to overheating and potential corrosion from sulfuric acid condensation.
Innovation Solution
An auxiliary heater is used to heat a gas stream by combusting hydrocarbon fuel with air, reducing oxygen concentration and preventing after burn, while maintaining the regenerator shell temperature above the dew point to prevent corrosion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If fluffing air is injected into the dense catalyst bed to fluidize catalyst, then catalyst fluidization is achieved, but oxygen in the air causes after burn in the regenerator
Solution Approach 1:
The patent changes the oxygen concentration parameter by using a gas stream with reduced oxygen content (less than 0.1% oxygen) instead of normal air for fluidizing the catalyst in the second chamber. This parameter change prevents after burn while maintaining catalyst fluidization capability
Solution Approach 2:
The patent creates an inert atmosphere in the second chamber by introducing a gas stream with less than 0.1% oxygen concentration. This inert environment prevents combustion of carbon monoxide that would otherwise occur with normal air, thereby preventing after burn while still allowing catalyst fluidization
2Use of energy by moving object
If the regenerator operates in partial burn mode, then heat recovery from carbon monoxide combustion is improved, but the risk of after burn increases
Solution Approach 1:
The patent enables partial burn operation (improving heat recovery) while controlling the oxygen concentration parameter in the second chamber to less than 0.1%. This dual parameter control allows heat recovery from carbon monoxide combustion in the first chamber while preventing after burn in the second chamber
Solution Approach 2:
The patent divides the regenerator into two chambers with different oxygen concentrations: the first chamber operates with higher oxygen for partial burn and heat recovery, while the second chamber operates with less than 0.1% oxygen to prevent after burn. This spatial segmentation allows both objectives to be achieved simultaneously
3Object-affected harmful factors
If the regenerator shell temperature is maintained high to prevent sulfuric acid condensation, then corrosion is prevented, but energy consumption increases
Solution Approach 1:
The patent converts the potentially harmful carbon monoxide that would cause after burn into a beneficial heat source by allowing its controlled combustion in the first chamber during partial burn operation. This heat helps maintain the regenerator shell temperature above the dew point, preventing sulfuric acid condensation and corrosion while improving overall energy efficiency
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
Enables safe operation of combustor regenerators in partial burn mode by reducing oxygen concentration and maintaining high temperatures to prevent corrosion, thus avoiding after burn and sulfuric acid condensation.
Implementation Method 1
An auxiliary heater is used to heat a gas stream by combusting hydrocarbon fuel with air, reducing oxygen concentration
Implementation Method 2
The heated gas stream is fed to the second chamber of a combustor regenerator to fluidize catalyst in the second chamber
Implementation Method 3
coked catalyst is continually removed from the reaction zone and replaced by essentially coke-free catalyst from the regeneration zone. During the regeneration process water is produced by the combustion of coke
Data Source
AI summary
A process for combusting coke from catalyst in partial burn mode is disclosed. The regenerator comprises two chambers. The bulk of the combustion is performed in a first chamber. Disengagement of the catalyst from gas is conducted in the second chamber. Heated gas with a low fraction of oxygen fluidizes catalyst in the second chamber.