Integrating Cyclic Dehydrogenation with FCC for Light Olefin Yield
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Solution Overview
Problem
The existing methods for producing light olefins, such as steam cracking, face challenges in achieving a high ratio of propylene to ethylene and inefficient conversion of by-products in fluidized catalytic cracking processes, leading to suboptimal yields and increased costs.
Innovation Solution
The process involves separating the effluent stream from a fluidized catalytic cracking unit into streams containing light olefins and paraffins, which are then passed through olefin conversion and dehydrogenation reactors to enhance light olefin production, utilizing existing equipment and energy streams, and recycling streams to maximize yield.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If steam cracking is used to produce light olefins, then ethylene production is achieved, but the propylene to ethylene ratio is low
Solution Approach 1:
The process segments the olefin production into two distinct pathways: steam cracking for ethylene production and catalytic dehydrogenation for propylene enrichment. The effluent streams are separated and processed through different reaction zones, allowing independent optimization of each pathway's product distribution
Solution Approach 2:
The patent combines steam cracking and catalytic dehydrogenation processes into an integrated system where both pathways operate simultaneously and their effluents are merged in the separation train. This allows the plant to produce both ethylene and propylene in optimized ratios while utilizing shared infrastructure
2Productivity
If by-products from fluidized catalytic cracking are not processed further, then process simplicity is maintained, but conversion efficiency and yield are suboptimal
Solution Approach 1:
The dehydrogenation catalyst is incorporated into the fluidized catalytic cracking process beforehand, enabling in-situ conversion of paraffinic by-products to olefins during the cracking process itself. This preliminary action converts low-value by-products into valuable olefins before they require separate processing
Solution Approach 2:
The dehydrogenation catalyst serves multiple functions: it dehydrogenates paraffins to olefins, modifies the product distribution of the FCC process, and extends catalyst life by reducing coke formation. This multi-functionality achieves by-product conversion without adding separate dedicated processing units
3Productivity
If existing infrastructure is fully utilized without modification, then capital costs are minimized, but process optimization and yield enhancement are limited
Solution Approach 1:
The process optimizes operating parameters such as temperature, catalyst-to-oil ratio, and residence time within the existing FCC and dehydrogenation units to maximize olefin yields. By adjusting these parameters rather than adding new equipment, the plant achieves enhanced productivity with minimal capital investment
Solution Approach 2:
The integrated dehydrogenation-FCC system uses its own internal heat and material streams to drive the dehydrogenation reactions. The exothermic cracking reactions provide heat for the endothermic dehydrogenation, and the catalyst system serves both cracking and dehydrogenation functions, reducing external utility requirements
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 increases light olefin yields by converting low-value paraffins into more valuable olefins and aromatics, optimizing the use of existing infrastructure and reducing capital and utility costs, while extending catalyst life and improving process efficiency.
Implementation Method 1
dehydrogenation catalyst having a metal component selected from the group consisting of platinum, chromium, zirconium and mixtures and combinations thereof
Implementation Method 2
The catalytic cracking step employs a zeolitic catalyst to convert a hydrocarbon stream having 4 or more carbon atoms per molecule to produce olefins having fewer carbon atoms per molecule
Implementation Method 3
Steam cracking or pyrolysis of hydrocarbons produces most of the ethylene and some propylene
Implementation Method 4
The feedstock is charged to a cracking zone in the presence of steam at effective thermal conditions
Data Source
AI summary
A process for increasing light olefin yields from the fluidized catalytic cracking process. The process combines small units to treat the paraffinic components in the product streams from the fluidized cracking process. The paraffins are dehydrogenated and light olefins are separated. Heavier olefins are passed to an olefin cracking unit for increasing the yields of ethylene and propylene.