Catalytic Cracking Unit Lateral Capacity for Coke Combustion Control
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Catalytic cracking units face challenges in maintaining heat balance and preventing catalyst deactivation due to high coke content and hydrogen levels, leading to hot spots and 'afterburning' when recycling coking cuts directly in the regenerator.
Innovation Solution
Recycling of coking cuts is redirected to a fluidized lateral capacity or tubular enclosure within the stripper, allowing for homogeneous coke deposition and vaporization, preventing hot spots and 'afterburning' by ensuring contact with the catalyst in a controlled environment before reintroduction to the dense phase.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by stationary object
If coking cut is recycled directly in the regenerator, then heat balance is improved, but hot spots and afterburning occur causing catalyst deactivation
Solution Approach 1:
The invention extracts the harmful combustion process from the regenerator by diverting the coking cut recycle stream to a separate lateral fluidized bed capacity. This separation allows coke combustion to occur in the lateral capacity rather than in the main regenerator, preventing hot spots and afterburning while maintaining heat balance in the overall system.
Solution Approach 2:
The lateral fluidized bed capacity acts as an intermediary device between the coking cut recycle stream and the main regenerator. It provides a controlled environment for coke combustion, mediating the heat transfer and preventing direct harmful effects on the catalyst in the main regenerator while still contributing to the overall heat balance.
2Use of energy by stationary object
If coking cut is recycled to the regenerator, then heat balance is improved, but afterburning occurs in the diluted phase
Solution Approach 1:
The invention extracts the afterburning phenomenon from the diluted phase of the regenerator by routing the coking cut recycle through a lateral fluidized bed capacity. This prevents the formation of cracked gases in the diluted phase that would cause afterburning, while the lateral capacity handles the combustion process in a controlled manner.
3Use of energy by stationary object
If high temperature combustion occurs in regenerator, then heat balance is maintained, but catalyst zeolite is deactivated
Solution Approach 1:
The invention extracts the high temperature combustion process from the catalyst bed in the regenerator and relocates it to the lateral fluidized bed capacity. This separation allows heat to be generated and maintained for heat balance while preventing direct exposure of the catalyst zeolite to temperatures that would cause deactivation.
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 enhances coke deposition homogeneity, maintains catalyst activity, and ensures heat balance by avoiding hot spots and 'afterburning', thereby optimizing the catalytic cracking process.
Implementation Method 1
contacting of the coked catalyst with said recycle flow in order to deposit additional coke on said catalyst in said diluted phase
Implementation Method 2
a lateral capacity (7) operated in a fluidized bed
Implementation Method 3
the coked catalyst leaving said reactor being introduced into a stripping zone, called a stripper, operating in a fluidized bed and having a dense phase (3)
Data Source
AI summary
The process comprises introducing a coked catalyst in an outlet of a main reactor (1) into a stripper operating in fluidized bed and having a dense phase topped with a dilute phase (2), and recycling cuts of light cycle oil, heavy cycle oil and/or slurry using coking cut in a fluidized lateral capacity placed in derivation of stripper and along a transfer line. A catalytic cracking unit has Conradson carbon of less than 0.1 and hydrogen content of greater than 12.7 wt.%. An upper portion of the transfer line has its origin at an upper point that is greater than the dense phase of stripper. The process comprises introducing a coked catalyst in an outlet of a main reactor (1) into a stripper operating in fluidized bed and having a dense phase topped with a dilute phase (2), and recycling cuts of light cycle oil, heavy cycle oil and/or slurry using coking cut in a fluidized lateral capacity placed in derivation of stripper and along a transfer line. A catalytic cracking unit has Conradson carbon of less than 0.1 and hydrogen content of greater than 12.7 wt.%. An upper portion of the transfer line has its origin at an upper point that is greater than the dense phase of stripper. A lower portion of the transfer line has its return to the dense phase of the stripper at a point below the upper point. The lateral capacity is placed upstream of a control valve of the flow rate of catalyst, is placed on the lower portion of the transfer line, is provided with a vent line for the return of the gas products in the dilute phase of the stripper, and comprises a lower packing placed in its lower part and located below the point of introduction of the recycle stream, and a higher packing placed in its upper part and located above the point of introduction of the catalyst by the transfer line. The flow of extraction of the catalyst introduced into the lateral capacity is 50-100 kg/m 2>/s. The residence time of the overall catalyst in the lateral capacity is 20-100 seconds. The catalyst taken from the dense phase of the stripper and brought into the lateral capacity is introduced into the dilute phase of the enclosure using a dispersion device. The coking cut is made within a tubular enclosure placed inside the stripper. An upper end of the enclosure opens into the dilute phase of the stripper, and the lower end of the enclosure opens into the dense phase of the stripper. The tubular enclosure is positioned so that the part immersed in the dense phase of the stripper is 30-100% of the total length of the tubular enclosure. A secondary reactor operates in parallel of the main reactor and works in operating conditions that is more stringent than the main reactor, and treats by mixing 4-5C olefinic cut and gasoline cut and/or recycled C5, C6, C7 or C8 oligomerat. An outlet temperature of the main reactor is 500-560[deg] C and C/O ratio is 5-10. An outlet temperature of the secondary reactor is 580-610[deg] C and the contact time is 50-200 ms. The recycled coking cut contains an external cut at the catalytic cracking unit type of wood or cellulose biomass, liquid hydrocarbon product from oil, pulverized coal, rich cut asphalt from a deasphalting unit, wax from a unit of indirect coal liquefaction, petroleum coke or a mixture of the fractions.