Reverse Flow Reactor Flue Gas Cascade Management
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Reverse flow reactors face challenges in managing heat introduction during the regeneration step, leading to excessive temperature spikes and waste heat loss due to inefficient flue gas management, which affects reaction kinetics and product yields.
Innovation Solution
The method involves segregating flue gas from reactors at later stages of regeneration from those at earlier stages, using higher temperature flue gas as a recycle gas/heat transport fluid and venting lower temperature flue gas, thereby reducing energy waste and maintaining efficient heat transfer while preventing temperature spikes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If flue gas is used to heat reactor surfaces during regeneration, then heat introduction efficiency is improved, but excessive temperature spikes occur
Solution Approach 1:
The patent segments the flue gas stream into different temperature zones by introducing cooling air at multiple points along the flue gas pathway. This allows the flue gas to be divided into a high-temperature portion (for effective heat transfer to reactor surfaces) and a cooled portion (to prevent excessive temperature spikes), thereby resolving the contradiction between heat introduction efficiency and temperature control.
Solution Approach 2:
Cooling air is introduced as an intermediary substance to moderate the temperature of the flue gas. This intermediary allows the system to maintain effective heat transfer capabilities while preventing harmful temperature spikes, as the cooling air mixes with the flue gas to create a temperature gradient that benefits both heat introduction and temperature control.
2Temperature
If flue gas is vented from the system, then temperature control is improved, but waste heat loss increases
Solution Approach 1:
The patent applies local quality by directing different portions of the flue gas to different destinations based on their temperature characteristics. The high-temperature portion is directed to where heat is needed (reactor surfaces), while the cooled portion is vented. This localized allocation optimizes both temperature control and minimizes waste heat loss, as only the necessary amount of heat is vented.
Solution Approach 2:
The system recovers heat from the flue gas by using it to heat reactor surfaces during regeneration, and only discards the portion of flue gas that has already transferred its useful heat. This selective discarding and recovering approach minimizes waste heat loss while maintaining effective temperature control.
3Productivity
If high temperature flue gas is recycled, then reaction kinetics are improved, but heat distribution control becomes difficult
Solution Approach 1:
The system dynamically adjusts the temperature and flow rate of recycled flue gas by introducing cooling air at controlled rates. This dynamic adjustment allows the system to maintain optimal temperatures for reaction kinetics while preserving the ability to control heat distribution, as the cooling air injection rate can be modulated in response to process conditions.
Solution Approach 2:
The patent changes physical parameters of the flue gas (temperature, pressure, flow rate) by introducing cooling air and controlling the recycling process. These parameter changes allow the system to optimize reaction kinetics through high-temperature recycling while maintaining heat distribution control through adjusted flow rates and temperature profiles.
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 reaction kinetics, increases product yields, and reduces energy costs by minimizing waste heat loss while maintaining high temperature operation, allowing for better control of heat distribution within the reactor system.
Implementation Method 1
reacting a first mixture comprising fuel and 0.1 vol % or more of O2 under first combustion conditions in a first combustion zone within a first reactor. The reacting can result in formation of a first flue gas comprising a first temperature of 400° C. or more and heating one or more surfaces in a first reaction zone to a regenerated surface temperature of 800° C. or more
Implementation Method 2
A first reactant stream can then be exposed to the one or more surfaces in the first reaction zone to increase the temperature of the first reactant stream
Implementation Method 3
exposing the first reactant stream to the catalyst composition in the first reaction zone at a temperature of 800° C. or more to form a first product stream
Implementation Method 4
reacting a first mixture comprising fuel and 0.1 vol % or more of O2 under first combustion conditions in a first combustion zone within a first reactor. The reacting can result in formation of a first flue gas comprising a first temperature of 400° C. or more
Data Source
AI summary
Systems and methods are provided for improving the operation of groups of reverse flow reactors by operating reactors in a regeneration portion of the reaction cycle to have improved flue gas management. The flue gas from reactor(s) at a later portion of the regeneration step can be selectively used for recycle back to the reactors as a diluent/heat transport fluid. The flue gas from a reactor earlier in a regeneration step can be preferentially used as the gas vented from the system to maintain the desired volume of gas within the system. This results in preferential use of higher temperature flue gas for recycle and lower temperature flue gas for venting from the system. This improved use of flue gas within a reaction system including reverse flow reactors can allow for improved reaction performance while reducing or minimizing heat losses during the regeneration portion of the reaction cycle.