Cooled Regenerated Catalyst Cycling in FCC Units
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Solution Overview
Problem
Current fluid catalytic cracking (FCC) technologies face challenges in improving gasoline quality, particularly with high olefin content, coke yield, and heat management, leading to suboptimal reaction conditions and product selectivity when processing heavy oil and low-grade gasoline.
Innovation Solution
A cycling method and equipment for cold regenerated catalysts are introduced, allowing for independent adjustment of catalyst and feed ratios, temperature control, and multi-point feeding to optimize reaction conditions, reduce coke and gas yield, and enhance catalyst activity, thereby improving gasoline quality and increasing liquid products yield.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If traditional hydrotreating process is used to reduce olefins in gasoline, then olefin content is reduced, but octane number is lost significantly
Solution Approach 1:
The patent changes the chemical parameters of the catalyst by controlling the temperature profile during regeneration. By limiting the maximum temperature and using a two-stage regeneration process (first stage at lower temperature to burn off coke, second stage at controlled temperature to maintain catalyst activity), the catalyst retains its ability to produce high-octane gasoline while still reducing olefin content through isomerization and aromatization reactions.
Solution Approach 2:
The patent dynamically adjusts the regeneration conditions by implementing a two-stage temperature control system. The first stage operates at lower temperature to remove coke, while the second stage maintains optimal temperature for catalyst activity. This dynamic temperature adjustment allows the catalyst to perform multiple functions (olefin reduction and octane enhancement) without significant loss in gasoline quality.
2Quantity of substance
If heavy oil catalytic cracking is performed with high coke yield, then more heat is produced, but excess heat must be removed requiring additional heat removing units
Solution Approach 1:
The patent converts the harmful excess heat into a beneficial resource by using it for steam generation and process heating. The high-temperature flue gas from the regenerator is directed to steam boilers to produce high-pressure steam, and excess heat is used for preheating feedstock and other process requirements. This transforms the energy loss into useful energy that supports the overall cracking process.
Solution Approach 2:
The patent implements a feedback system where the heat generated from coke combustion is continuously monitored and redirected to meet process requirements. The steam generated from excess heat is fed back into the system for various uses including catalyst regeneration support and process heating, creating a closed-loop energy management system that optimizes heat utilization.
3Temperature
If catalyst cooler is used to remove heat from regenerated catalyst, then heat is removed, but only heat from cold regenerated catalyst can be taken which limits optimization of reaction system operating conditions
Solution Approach 1:
The patent makes the regenerator serve multiple functions: it not only regenerates the catalyst by burning off coke but also acts as a heat source for steam generation, process heating, and power production. The regenerator's thermal energy is utilized through various heat exchangers and steam boilers, allowing the system to optimize reaction conditions independently while efficiently managing heat from the regeneration process.
Solution Approach 2:
The patent segments the heat removal process into multiple stages and locations: primary heat removal occurs in the regenerator itself through controlled combustion, secondary heat removal occurs through heat exchangers that transfer heat to process streams, and tertiary heat removal occurs through steam generation systems. This segmentation allows flexible heat management and independent optimization of reaction conditions.
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 method effectively reduces olefin content, increases gasoline octane number, and enhances processing capacity by optimizing reaction temperatures and catalyst activity, while maintaining efficient regeneration and heat management.
Implementation Method 1
the regenerator is provided with one or more catalyst coolers (8A, 8B)
Implementation Method 2
the spent catalyst...enters into regenerator to burn for regeneration
Data Source
AI summary
A method for circulating a cooled regenerated catalyst comprises the following steps: a regenerated catalyst derived from a regenerator is cooled to 200-720° C. by a catalyst cooler, which either directly enters into a riser reactor without mixing with hot regenerated catalyst, or enters the same after mixing with another portion of uncooled hot regenerated catalyst and thereby obtaining a hybrid regenerated catalyst with its temperature lower than that of the regenerator; a contact reaction between a hydrocarbon raw materials and the catalyst is performed in the riser reactor; the reaction product is introduced into a settling vessel to separate the catalyst and oil gas; the separated catalyst ready for regeneration is stream-stripped in a stream stripping phase and enters the regenerator for regeneration through charring; after cooling, the regenerated catalyst returns to the riser reactor for recycling.