Catalyst Stripping System for Oxygenate Conversion
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Solution Overview
Problem
The accumulation of coke deposits on catalysts used in oxygenate-to-olefin conversion processes reduces their activity, and the regeneration process introduces entrained gases like carbon monoxide and carbon dioxide, which contaminate the olefin product and cause operational issues downstream.
Innovation Solution
A method and system for stripping entrained gases from regenerated catalysts using nitrogen gas in a stripper with baffles to enhance contact between the gas and catalyst, effectively removing carbon dioxide, carbon monoxide, and oxygen before returning the catalyst to the reactor, thereby maintaining catalytic activity and reducing downstream contamination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the catalyst is regenerated by combustion with oxygen-containing air to remove coke deposits, then the catalytic activity is restored, but entrained gases (carbon monoxide, carbon dioxide, oxygen) contaminate the olefin product and cause downstream operational issues
Solution Approach 1:
The harmful entrained gases (carbon monoxide, carbon dioxide, and oxygen) are extracted from the regenerated catalyst through a stripping process using nitrogen gas. The stripping section separates these contaminants from the catalyst particles, removing them before the catalyst returns to the reactor, thus preventing downstream contamination while maintaining catalytic activity.
Solution Approach 2:
Nitrogen gas serves as an intermediary stripping medium that contacts the regenerated catalyst in the stripping section. The nitrogen facilitates the removal of entrained combustion gases from the catalyst particles through mass transfer, acting as a mediator between the contaminated catalyst and the clean reactor environment without introducing additional harmful substances.
2Manufacturing precision
If carbon dioxide is removed from the olefin product using caustic scrubbing, then the polymer grade quality is improved, but caustic consumption increases and operational problems occur
Solution Approach 1:
The stripping section performs preliminary removal of carbon dioxide and other entrained gases from the regenerated catalyst before the catalyst contacts the oxygenate feedstock in the reactor. By eliminating carbon dioxide at the source (the catalyst) rather than treating it downstream in the product stream, the need for caustic scrubbing is reduced or eliminated, preventing caustic consumption and associated operational problems.
3Productivity
If the catalyst is continuously withdrawn and regenerated to maintain activity, then the conversion efficiency is improved, but the process complexity and downstream processing difficulties increase
Solution Approach 1:
The stripping section is merged with the regenerator system, combining the catalyst regeneration function with the entrained gas removal function in an integrated process. The stripping section receives regenerated catalyst directly from the regenerator and returns stripped catalyst to the reactor, creating a unified system that maintains high conversion efficiency while simplifying downstream processing by eliminating contaminant introduction.
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 significantly reduces the concentration of contaminants in the olefin product, decreases caustic consumption, and minimizes operational problems in downstream units by effectively removing entrained gases, thus maintaining the catalyst's activity and reducing processing difficulties.
Implementation Method 1
stripping the regenerated catalyst of gases entrained during the regeneration step
Implementation Method 2
contacting the oxygenate-containing feedstock with the catalyst in the reactor and converting the oxygenate-containing feedstock to olefins
Implementation Method 3
The combustion air used in regenerating the catalyst leaves carbon monoxide, oxygen, and carbon dioxide gases entrained in the catalyst. Oxygen is not a natural byproduct of the oxygenate-to-olefin reaction and when introduced through entrainment with regenerated catalyst creates processing difficulties downstream.
Data Source
AI summary
A system of converting oxygenate-containing feedstock to light olefins comprises charging a reactor with catalyst, feeding the feedstock into the reactor, contacting the feedstock with the catalyst and converting the feedstock to olefins while depositing byproducts on catalyst resulting in spent catalyst, regenerating the spent catalyst by combustion gases, and stripping the regenerated catalyst of gases entrained in the regenerating step. The stripping step is accomplished using nitrogen gas to strip the entrained gases from the regenerate catalyst. In one embodiment, regenerated catalyst is passed through a regenerated catalyst stripper before it is returned to the reactor.