Self-Stripping FCC Riser Cyclone Design
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Solution Overview
Problem
In fluid catalytic cracking (FCC) processes, existing cyclone separators face challenges in efficiently stripping residual carrier fluids from disentrained catalyst particles, which affects reaction control and product profiles, and requires external stripping gases, increasing mechanical complexity.
Innovation Solution
A self-stripping cyclone design that integrates stripping functionality within the cyclone separator, allowing for the introduction of stripping fluid through openings in the cyclone wall, creating a stripping zone between the vortex and particulate discharge outlet, enabling efficient diffusion of residual carrier fluids without an external source, reducing mechanical complexity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If external stripping gas sources are used to diffuse residual hydrocarbons from catalyst particles, then stripping effectiveness is improved, but mechanical complexity increases
Solution Approach 1:
The patent combines the cyclone separator and stripping chamber into a single integrated device. The stripping chamber is formed within the cyclone separator body, eliminating the need for separate external stripping equipment. This merging of functions reduces mechanical complexity while maintaining stripping effectiveness through the integrated design where stripped particles fall directly into the stripping chamber.
Solution Approach 2:
The cyclone separator is designed to perform multiple functions: phase separation and stripping. The same device that separates catalyst particles from hydrocarbon vapors also serves as the stripping chamber where residual hydrocarbons are diffused from particles. This multi-functionality eliminates the need for separate stripping gas injection systems and external stripping equipment.
2Device complexity
If residual carrier fluid is not displaced from catalyst particles, then mechanical complexity is reduced, but product yield control and reaction selectivity deteriorate
Solution Approach 1:
The stripping chamber is integrated within the cyclone separator body, creating a compact design that performs both separation and stripping functions in one device. This merging maintains mechanical simplicity while ensuring effective displacement of residual carrier fluid through the stripping process that occurs within the same housing.
Solution Approach 2:
The cyclone separator is divided into distinct functional zones: the separation zone where particles are separated from vapors, and the stripping chamber where residual fluids are displaced. This segmentation allows each zone to optimize its specific function while maintaining overall system simplicity.
3Productivity
If contact time between catalyst and hydrocarbons is increased to improve reaction rates, then productivity increases, but control over product profiles and delta coking worsens
Solution Approach 1:
The stripping action occurs immediately after separation within the integrated cyclone separator, before particles are discharged. This preliminary stripping removes residual hydrocarbons from catalyst particles right at the point of separation, preventing further unwanted reactions while maintaining the benefits of rapid mixing and separation.
Solution Approach 2:
The integrated design enables rapid transition from separation to stripping within the cyclone separator. Particles are quickly separated and immediately subjected to stripping action, minimizing the time they spend in contact with residual hydrocarbons and preventing unwanted side reactions like delta coking.
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 design enhances process productivity and selectivity by effectively stripping hydrocarbon vapors from FCC catalyst particles, minimizing delta coking and maintaining optimal contact times, while reducing mechanical complexity and operational costs.
Implementation Method 1
separating a mixture of two or more phases, such as for example, suspensions of particulates in a carrier fluid, under a centrifugal force generated by centripetal motion
Implementation Method 2
Cyclonic separation involves separating a mixture of two or more phases
Implementation Method 3
introducing a stripping gas, such as for example, air, steam, ammonia, flue gas, or similar gases, to diffuse the residual hydrocarbons away from the disentrained catalyst particles
Data Source
AI summary
Apparatus and method are provided for separating and stripping suspensions comprising catalyst particles transported in vapors from the fluid catalytic cracking riser/reactor. Particles are disentrained from vapor in a vortex zone 112 of the primary cyclonic separator 100. The disentrained particles enter a stripping zone 126, wherein the particles are contacted with a stripping gas 136 to recover vapors entrained and adsorbed onto the catalyst. The stripping gas 136 enters stripping zone 126 via perforations in the wall of the cyclone 100. The stripping gas 136 limits the residual catalytic conversion of hydrocarbon vapors and formation of delta-coke on the catalyst. Stripped catalyst is delivered from the cyclone stripping zone 126 via a dipleg 130 connected to a bottom of the cyclone 100, and enters an FCC stripping vessel. Solids-lean stripping gas and vapors from the catalyst particles are blended with the carrier fluid and discharged from the cyclone.