Dual Riser Cyclone Venting Isolation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
In dual riser fluid catalytic cracking (FCC) units, cross-talk between independent cyclone systems within a single vessel leads to thermal cracking and reduced gasoline yield due to imbalances in flow, causing vapor from one cyclone system to flow into the vent of another, resulting in prolonged exposure to high temperatures.
Innovation Solution
Installing a vent in only one cyclone system and sealing the other to prevent vapor entry and exit, ensuring independent operation and eliminating cross-talk by routing vapor discharge directly to a fluid discharge line, thereby avoiding contamination and thermal cracking.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multiple vented independent cyclone systems are utilized within a single disengager vessel, then catalyst stripping vapors can exit with the riser product vapors, but small imbalances in flow produce cross-talk in which riser product vapors exit the vent of one cyclone system and flow into the vent of another cyclone system
Solution Approach 1:
The harmful element (cross-talk between cyclone systems) is eliminated by removing the vent from the disengager vessel entirely. Each cyclone system is equipped with its own independent vent, extracting the vapor removal function from the shared vessel level to the individual cyclone level, thereby preventing vapor migration between systems.
Solution Approach 2:
The vapor removal function is segmented from a centralized vessel-level vent to individual cyclone-level vents. This segmentation isolates each cyclone system's vapor pathway, preventing cross-talk while maintaining the ability to remove stripping vapors from each system independently.
2Reliability
If cross-talk occurs between cyclone systems, then riser product vapors are exposed to high temperatures within the disengager vessel for prolonged periods of time, but this results in thermal cracking and the associated loss in gasoline yield and increase in dry gas yield
Solution Approach 1:
The venting function is extracted from the high-temperature disengager vessel environment to individual cyclone systems. By placing vents directly on each cyclone, vapors are removed at the source before they can be exposed to prolonged high temperatures in the vessel, preventing thermal cracking and preserving gasoline yield.
Solution Approach 2:
Vapors are rapidly removed from each cyclone system through dedicated vents, skipping the prolonged high-temperature exposure period in the disengager vessel. This rapid vapor evacuation prevents the thermal cracking reactions that would otherwise occur during extended residence time at high temperatures.
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 solution prevents undesirable thermal cracking reactions, maintains high gasoline yield, and reduces the production of less valuable products like coke and dry gas by isolating cyclone systems, ensuring precise control over catalyst and hydrocarbon contact times.
Implementation Method 1
Cyclonic separation involves separating a mixture of two or more phases, for example, suspensions of particulates in a carrier fluid, under a centrifugal force generated by centripetal motion.
Data Source
AI summary
Two or more cyclone systems can be contained in a single vessel. Each cyclone system can be in fluid communication with an inlet stream and a fluid discharge line. First cyclone system can include a vent open to the cyclone containing vessel. Second cyclone system can be sealed to restrict fluid entry from and/or exit into vessel, which can inhibit product vapors from exiting the vent of one cyclone system into the vessel and flowing into the vent of the other cyclone system.