Catalytic Conversion Apparatus for Light Olefin Yield
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Solution Overview
Problem
Current catalytic cracking processes for producing light olefins, such as propylene, from feed oils have low yields and produce excessive dry gas, failing to meet increasing demand and efficiency requirements.
Innovation Solution
A catalytic conversion apparatus comprising a riser reactor followed by a dense bed reactor, with a stripper located below the dense bed reactor, allowing for separate reaction zones and catalyst regeneration, which enhances catalyst activity and efficiency by controlling catalyst flow and steam utilization, thereby increasing light olefin production and reducing dry gas yield.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If catalytic cracking is used to produce light olefins from feed oil, then light olefins can be produced, but the yield is low and excessive dry gas is produced
Solution Approach 1:
The catalytic cracking process is divided into two distinct stages: a first riser reactor for initial cracking and a second riser reactor for deep cracking. This segmentation allows optimization of reaction conditions in each stage, with the first riser producing intermediate products and the second riser converting them to light olefins, thereby improving light olefin yield while controlling dry gas formation
Solution Approach 2:
Different reaction parameters are applied in each riser stage. The first riser operates under milder conditions to produce gasoline and light cycle oil, while the second riser uses more severe cracking conditions (higher temperature, different catalyst properties) to maximize light olefin production from the intermediate products, optimizing the balance between yield and dry gas formation
2Productivity
If severe cracking conditions are applied to increase light olefin yield, then more light olefins are produced, but dry gas yield increases simultaneously
Solution Approach 1:
The cracking process is segmented into two risers with different severity levels. The second riser applies severe cracking conditions specifically to convert intermediate products to light olefins, while the first riser operates under milder conditions. This prevents excessive cracking that would lead to dry gas formation, maintaining high light olefin productivity without proportional increase in dry gas yield
Solution Approach 2:
Gasoline and light cycle oil from the first riser act as intermediaries that are further cracked in the second riser. This intermediary stage allows controlled conversion to light olefins, preventing direct severe cracking of feed oil that would produce excessive dry gas, thus achieving high productivity with minimized dry gas loss
3Productivity
If a single riser reactor is used for catalytic cracking, then the process is simple, but the conversion efficiency to light olefins is insufficient
Solution Approach 1:
The reactor system is segmented into two risers with distinct functions: the first riser for initial cracking and product formation, and the second riser for deep cracking to light olefins. This segmentation achieves high conversion efficiency through optimized staged reactions, while the shared disengager and regenerator mitigate the complexity increase by consolidating common components
4Quantity of substance
If catalyst activity is enhanced to improve light olefin yield, then conversion efficiency increases, but catalyst deactivation and dry gas formation increase
Solution Approach 1:
Catalyst activity is segmented across two stages. The first riser uses catalyst with moderate activity to produce intermediates, while the second riser employs highly active catalyst specifically for light olefin production from intermediates. This prevents overcracking and excessive dry gas formation that would result from using high-activity catalyst throughout the entire process
Solution Approach 2:
Different catalyst properties are applied locally in each riser stage. The second riser uses catalyst with higher activity and different composition optimized for light olefin production, while the first riser uses catalyst suited for initial cracking. This local optimization achieves high light olefin yield without the dry gas formation associated with uniformly high catalyst activity
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
The apparatus achieves a high yield of light olefins, especially propylene, with reduced dry gas production, improved catalyst utilization, and lower energy consumption, addressing the limitations of existing technologies.
Implementation Method 1
catalytically cracking feed oil in the absence of hydrogen
Implementation Method 2
deep cracking is further carried out under a very severe condition
Implementation Method 3
a stripper, wherein the stripper is located below the dense bed reactor
Data Source
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AI summary
The present invention relates to a catalytic conversion apparatus, characterized in that said apparatus comprises at least one feed oil cracking riser reactor, a dense bed reactor, a disengager, and a stripper, wherein said stripper locates below said dense bed reactor and communicates directly with the lower part of the dense bed reactor or through a fluid-communicating channel, the outlet of at least one of said riser reactor(s) communicates with the lower part of said dense bed reactor or any part of said fluid-communicating channel, the outlet of said dense bed reactor communicates with the inlet of a gas-solid separating apparatus located in said disengager through said disengager and/or through an optional transporting channel, the catalyst outlet of said disengager communicates with at least one position selected from the upper part of said stripper, any part of said fluid-communicating channel, and the lower part of said dense bed reactor, through at least one catalyst transporting channel. The catalytic conversion apparatus according to the present invention sets up at least one riser reactor and a dense bed reactor to carry out further cracking of the intermediate products, produced from the feed oil by the cracking reaction in the riser, in the dense bed reactor. Moreover, the spent catalysts discharged from the outlet of the dense bed reactor can be introduced into the stripper via a specific catalyst transporting channel, so as to maintain higher activity and temperature of the catalyst in the dense bed reactor and be advantageous to deeper cracking of the intermediate products in the dense bed reactor so as to produce more light olefins, particularly propylene.