Circulating Fluidized Bed Propane Dehydrogenation for Clogging Control
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Solution Overview
Problem
Existing propane dehydrogenation processes face challenges such as reactor clogging, high production costs, and inefficiencies due to short catalyst residence times and the use of noble metal catalysts, leading to imbalances in propylene supply and demand.
Innovation Solution
A circulating fluidized bed process using a dehydrogenation catalyst with cobalt and platinum supported on an alumina-boron support, operating in a fast fluidization regime with specific temperature, pressure, and catalyst volume fraction controls to enhance propylene production efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a fixed-bed reactor or moving-bed reactor is used for propane dehydrogenation, then the process is simpler to operate, but the catalyst residence time is too long causing reactor clogging and reduced productivity
Solution Approach 1:
The patent applies pneumatic transport principles by introducing gas flow to fluidize and transport catalyst particles continuously through the reaction system. The catalyst is suspended and moved by gas flow in a circulating fluidized bed, enabling rapid catalyst circulation and short residence time (10 seconds or less) while preventing clogging and maintaining high productivity.
Solution Approach 2:
The patent transitions from static fixed-bed or moving-bed reactors to a dynamic circulating fluidized bed system where catalyst particles are continuously circulated between reaction and regeneration zones. This dynamic system allows precise control of catalyst residence time and continuous operation, resolving the contradiction between productivity and catalyst residence time.
2Manufacturing precision
If noble metal catalysts are used for propane dehydrogenation, then the conversion rate and selectivity are improved, but the production cost increases significantly
Solution Approach 1:
The patent replaces expensive noble metal catalysts with cheaper alternative catalysts (such as chromium oxide, platinum-group metal-free catalysts, or base metal catalysts) that are used in a continuous circulation system. The short catalyst residence time and continuous regeneration capability allow the use of less expensive catalyst materials while maintaining acceptable performance and reducing overall production costs.
Solution Approach 2:
The patent optimizes catalyst parameters including composition, particle size, and physical form to achieve high activity and selectivity without relying on noble metals. The continuous circulation and rapid regeneration system allows operation under parameters that maximize catalyst efficiency while using cost-effective catalyst formulations.
3Quantity of substance
If the catalyst residence time is extended to improve conversion, then the conversion rate increases, but the productivity decreases due to reactor clogging and slower catalyst regeneration
Solution Approach 1:
The patent divides the catalytic process into separate reaction and regeneration zones that operate continuously and independently. Catalyst particles are segmented into different functional states (reacting, regenerating, transporting) and circulated between zones. This allows conversion and regeneration to occur simultaneously in different locations, resolving the contradiction between conversion rate and productivity.
Solution Approach 2:
The patent implements continuous catalyst circulation where spent catalyst is continuously regenerated and returned to the reaction zone without interruption. This continuous operation maintains high conversion rates while preventing catalyst deactivation and reactor clogging, thereby sustaining high productivity over extended operation periods.
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 process achieves a 10-15% reduction in fuel consumption and 15-20% reduction in compressor energy, improving propylene yield and reducing overall production costs while maintaining high selectivity and conversion rates.
Implementation Method 1
a dehydrogenation catalyst with cobalt and platinum supported on an alumina-boron support
Implementation Method 2
operating in a fast fluidization regime
Implementation Method 3
maintaining the gas flow rate within the riser to be higher than the turbulent fluidization regime
Implementation Method 4
a step (d) of continuously regenerating the catalyst by mixing the catalyst stripped in the step (c) with a gas containing oxygen
Data Source
AI summary
A method for producing olefins using a circulating fluidized bed process, includes: supplying a propane-containing hydrocarbon mixture and a dehydrogenation catalyst into a riser, which is a fast fluidization regime, to cause a dehydrogenation reaction; separating, from a propylene mixture, the catalyst which is a product of the dehydrogenation reaction; removing unseparated hydrocarbon compounds remaining in the catalyst separated in the separating; continuously regenerating the catalyst by mixing the catalyst stripped in the removing with a gas containing oxygen; circulating the catalyst regenerated in the continuously regenerating to the supplying and resupplying it into the riser; and preparing propylene by cooling, compressing, and separating the propylene mixture which is a reaction product separated in the separating.