Fluid Catalytic Cracking Light Olefin Recovery via Absorption
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional Fluidized Catalytic Cracking (FCC) processes struggle to efficiently recover and separate light olefins such as ethylene and propylene due to the presence of coke, which deactivates catalysts and results in heat loss, and existing gas recovery units are not designed to handle increased volumes of these valuable hydrocarbons.
Innovation Solution
A process involving a fluidized reactor zone where a heavy hydrocarbon feedstock is contacted with a catalyst composition including a large pore molecular sieve and a medium or smaller pore zeolite, followed by an absorption system using a solvent to separate and recover C2+ hydrocarbons, specifically ethylene and propylene, with a separation system that returns a portion of the solvent for reuse.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional FCC processes are used to crack heavy hydrocarbons, then catalyst deactivation by coke occurs, but light olefin recovery and separation becomes inefficient
Solution Approach 1:
The patent extracts and separates light olefins (C2-C4 hydrocarbons) from the FCC process stream using a dedicated separation system with absorption and stripping units. This extraction operation removes light olefins from the reactor effluent before they can be lost or cause unwanted reactions, thereby improving light olefin yield while maintaining catalyst activity through continuous removal of harmful products.
Solution Approach 2:
The patent introduces an intermediary separation system between the FCC reactor and the product outlet. This intermediary system includes absorption columns with solvent streams that mediate the separation process, allowing selective recovery of light olefins while protecting the catalyst system from deactivation by coke and other harmful substances.
2Reliability
If coke is removed from catalyst through oxidation in regenerator, then catalyst is regenerated, but heat is lost with flue gas
Solution Approach 1:
The patent converts the harmful effect of coke oxidation heat loss into a beneficial process by using the hot flue gas from the regenerator to preheat the incoming feedstock and to provide the heat necessary for the absorption and stripping operations. This heat integration reduces external energy requirements and improves overall process efficiency while maintaining effective catalyst regeneration.
Solution Approach 2:
The patent changes the temperature parameter utilization by directing hot flue gas to heat exchangers that transfer thermal energy to the feedstock and process streams. This parameter change transforms waste heat into a useful resource, reducing energy loss while maintaining the regenerator's ability to effectively remove coke from the catalyst.
3Adaptability or versatility
If existing gas recovery units are used, then they can handle light olefins, but they are not designed for increased volumes
Solution Approach 1:
The patent implements a dynamic separation system that can adapt to varying volumes of light olefin production. The absorption and stripping units are designed with flexible flow rates and can be adjusted to handle increased volumes of light olefins while maintaining separation efficiency. This dynamic capability allows the system to respond to changes in FCC operation and light olefin generation rates.
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 effectively increases the yield of light olefins by efficiently separating and recovering ethylene and propylene, reducing coke-related catalyst deactivation and heat loss, and optimizing the use of existing equipment to handle increased volumes of these valuable hydrocarbons.
Implementation Method 1
contacting a starting material whether it be vacuum gas oil, reduced crude, or another source of relatively high boiling hydrocarbons with a catalyst such as composed of finely divided or particulate solid material
Implementation Method 2
The cracking reaction typically deposits coke on the catalyst. Catalyst exiting the reaction zone is commonly referred to as being 'spent', i.e., partially deactivated by the deposition of coke upon the catalyst
Implementation Method 3
At least a portion of the first separation system stream is contacted in an absorption system with an absorption solvent at effective conditions to absorb a significant portion of C2+ hydrocarbons
Implementation Method 4
The fluidized catalyst, as well as providing a catalytic function, serves as a vehicle for the transfer of heat from zone to zone
Implementation Method 5
then to a regenerator for the purpose of removing the coke by oxidation with an oxygen-containing gas
Data Source
AI summary
Processing schemes and arrangements are provided for the processing a heavy hydrocarbon feedstock via fluidized catalytic cracking with selected hydrocarbon fractions including light olefins being obtained via absorption and separation product recovery.