Indirect Catalyst Heating via Flue Gas Tubes
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Solution Overview
Problem
Current dehydrogenation processes for producing light olefins, such as PDH and FCC, face challenges in providing sufficient heat to the catalyst due to low coke yield and risks of catalyst damage from direct fuel combustion, leading to incomplete combustion and exposure to intense heat.
Innovation Solution
An indirect heating process using a hot flue gas generated by igniting a fuel stream, where the hot flue gas flows within a heating tube to heat the catalyst stream outside, avoiding direct contact and incomplete combustion, and can be implemented using catalyst heaters outside or tube-fired burners within the regeneration vessel.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If fuel is burned directly in the catalyst bed of the regenerator, then the heat requirement for endothermic reactions is met, but incomplete combustion of fuel and contact of catalyst with contaminated fuel gas occur, and catalyst may be damaged due to direct contact with intense heat
Solution Approach 1:
The patent introduces a heat exchange medium (flue gas) as an intermediary to transfer heat from the fuel combustion zone to the catalyst stream. The flue gas flows through heat exchange tubes while the catalyst flows outside the tubes, enabling indirect heat transfer without direct contact between the catalyst and fuel or flame, thus avoiding catalyst contamination and damage while still meeting the heat requirement for endothermic reactions
2Use of energy by moving object
If coke combustion is used to supply heat to the catalyst, then the endothermic heat requirement is partially met, but the coke yield is relatively low and insufficient to supply the entire heat requirement
Solution Approach 1:
The patent utilizes the flue gas generated from fuel combustion as a self-service heat source. The combustion process produces hot flue gas that naturally flows through the heat exchange tubes, and this waste heat is then used to heat the catalyst stream, eliminating the need for additional fuel consumption and fully meeting the endothermic heat requirement
Solution Approach 2:
The patent recovers the waste heat from the flue gas that would otherwise be discarded. By directing the hot flue gas through heat exchange tubes in contact with the catalyst stream, the system captures and utilizes the thermal energy that would normally be lost, thereby meeting the complete heat requirement for endothermic reactions without relying on limited coke combustion
3Reliability
If indirect heating using hot flue gas is implemented, then catalyst damage is avoided and heat transfer efficiency is enhanced, but additional heating equipment (heating tubes or external heaters) is required
Solution Approach 1:
The patent integrates the heat exchange function into the existing regenerator structure. The heat exchange tubes are positioned within the regenerator vessel, and the flue gas flow path is incorporated into the existing gas circulation system. This multi-functional design allows the regenerator to simultaneously perform catalyst regeneration and catalyst heating functions without requiring completely separate heating equipment
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 method effectively heats the catalyst to the required temperature without risking catalyst damage, reduces the need for coke combustion, and enhances heat transfer efficiency, ensuring consistent and safe heating for endothermic reactions.
Implementation Method 1
A hot flue gas flows within a heating tube to heat the catalyst stream flowing outside the heating tube
Implementation Method 2
A hot flue gas flows within a heating tube to heat the catalyst stream flowing outside the heating tube
Implementation Method 3
A hot flue gas is generated by igniting a fuel stream
Data Source
AI summary
A process and apparatus for indirect heating of catalyst in the regeneration zone is disclosed. A hot flue gas flows within a heating tube and the catalyst to be heated flows outside the heating tube. The hot flue gas is generated by igniting a fuel stream. The hot flue gas is generated directly in the heating tube or is generated in a separate burner outside the heating tube.