Integrated Thermal Catalytic Cracking Olefin Yield
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Solution Overview
Problem
Steam cracking furnaces face challenges in achieving high ethylene yield due to their non-selective nature, while catalytic cracking processes are selective but cannot produce high ethylene yields, and both are limited by over-conversion and coking issues.
Innovation Solution
A process combining thermal cracking of hydrocarbons in a pyrolysis reactor followed by catalytic cracking, where the hydrocarbon feed is pre-treated at ultra-low conversion to produce a cracked effluent that is then further processed in a catalytic cracking reaction zone, optimizing conditions to enhance selectivity and yield of olefins and dienes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If thermal cracking is used to produce olefins, then high ethylene yield is achieved, but selectivity is poor and over-conversion occurs
Solution Approach 1:
The cracking process is divided into two distinct stages: thermal cracking in a first zone to break down hydrocarbons into smaller molecules, followed by catalytic cracking in a second zone to selectively convert them to desired olefin products. This segmentation allows each process to operate under optimized conditions for its specific function.
Solution Approach 2:
A catalyst is introduced as an intermediary substance in the second cracking zone to mediate the conversion of thermally cracked hydrocarbons to olefins. The catalyst provides selective pathways that improve product distribution and reduce over-conversion, while the thermal cracking zone acts as an intermediary step to prepare the feedstock for catalytic processing.
2Manufacturing precision
If catalytic cracking is used to improve selectivity, then product distribution is improved, but ethylene yield is limited
Solution Approach 1:
Thermal cracking is performed as a preliminary action in the first zone to break down heavy hydrocarbons into lighter, more reactive molecules. This pre-treatment prepares the feedstock for the subsequent catalytic cracking, ensuring that the catalyst can effectively convert the material into desired olefin products with high selectivity.
Solution Approach 2:
The patent merges thermal cracking and catalytic cracking into a single integrated process system. The thermal cracking zone and catalytic cracking zone operate in sequence within the same reactor system, combining the high-temperature non-selective breaking of bonds with the catalyst-driven selective transformations to achieve both high ethylene yield and improved selectivity simultaneously.
3Productivity
If high conversion is operated to maximize product output, then productivity increases, but coking and catalyst deactivation occur
Solution Approach 1:
The process uses partial action by performing thermal cracking to a limited extent (ultra-low conversion) before introducing catalytic cracking. This partial thermal cracking prepares the feedstock without causing excessive coking, while the catalytic cracking then completes the conversion to desired products. The combination achieves high overall productivity while maintaining catalyst stability.
Solution Approach 2:
The patent converts the potentially harmful effect of coking into a beneficial process control mechanism. By operating the thermal cracking zone at ultra-low conversion, minimal coking occurs. The catalytic cracking zone then selectively processes the thermally cracked material, and any coke formed is managed through the catalytic system's inherent properties, extending catalyst life while maintaining high productivity.
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 integrated approach results in improved selectivity, higher yields of target products, reduced energy consumption, and lower capital costs, enabling the production of more olefins and propylene with a higher propylene-to-ethylene ratio compared to traditional methods, while minimizing coke formation and extending catalyst life.
Implementation Method 1
thermally cracking a hydrocarbon containing feed to produce a cracked hydrocarbon effluent containing a mixture of olefins and paraffins
Implementation Method 2
catalytically cracking the cracked hydrocarbon effluent to produce a catalytically cracked effluent containing additional olefins and/or dienes
Data Source
AI summary
Embodiments disclosed herein relate to systems and processes for producing olefins and/or dienes. The processes may include: thermally cracking a hydrocarbon containing feed to produce a cracked hydrocarbon effluent containing a mixture of olefins and paraffins; and catalytically cracking the cracked hydrocarbon effluent to produce a catalytically cracked effluent containing additional olefins and/or dienes. The systems may include a reaction zone for thermally cracking a hydrocarbon containing feed to produce a cracked hydrocarbon effluent containing a mixture of olefins and paraffins; and, a catalytic cracking reaction zone for catalytically cracking the cracked hydrocarbon effluent to produce a catalytically cracked hydrocarbon effluent containing additional olefins and/or dienes.