Variable Partial Bypass Heat Exchanger for Thermal Runaway Prevention
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Solution Overview
Problem
Existing heat exchanger systems face challenges in controlling the temperature of internal components, leading to potential catastrophic failures due to uncontrolled combustion and overheating, especially when handling oxygen-rich oxidants, and require a method to safely achieve a wider range of process gas temperatures without excessive cost or material constraints.
Innovation Solution
A counter-flow shell and tube heat exchanger system utilizing variable partial bypass of a reactant flow, where a feed flow is divided into main and bypass flows, with a control valve adjusting their proportions based on measured temperature to manage heat transfer and prevent overheating, allowing for safer operation and broader temperature ranges.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a single stream of oxidant is sent to a heat exchanger for pre-heating, then heat recovery efficiency is improved, but the risk of catastrophic uncontrolled combustion increases due to unburnt fuel contact with oxygen
Solution Approach 1:
The oxidant stream is divided into multiple separate streams, each sent to its own heat exchanger. This segmentation prevents unburnt fuel from different combustion zones from mixing with oxygen-rich oxidant, thereby eliminating the risk of catastrophic uncontrolled combustion while maintaining heat recovery efficiency across multiple independent channels.
2Use of energy by moving object
If heat exchanger internal components are exposed to high temperatures, then heat transfer efficiency is improved, but the risk of overheating and component failure increases
Solution Approach 1:
The system incorporates variable bypass flow paths that allow dynamic adjustment of oxidant flow rates through the heat exchangers. This dynamic control enables the system to adapt to varying temperature conditions, preventing overheating of internal components while maintaining optimal heat transfer efficiency by directing flow based on real-time thermal conditions.
3Productivity
If oxygen-rich oxidants are handled in heat exchangers, then combustion efficiency is improved, but the risk of uncontrolled combustion increases
Solution Approach 1:
The system separates the oxidant flow into multiple independent streams, each handled by its own heat exchanger. This segmentation isolates oxygen-rich oxidant from unburnt fuel sources, preventing the conditions necessary for uncontrolled combustion while maintaining high combustion efficiency through optimized heat recovery in each separate channel.
4Temperature
If heat exchanger materials are made from exotic materials to withstand high temperatures, then temperature range capability is improved, but manufacturing cost increases
Solution Approach 1:
The system uses variable bypass flow control to dynamically manage temperature levels in the heat exchangers, allowing standard materials to operate within safe temperature ranges. This dynamic flow management eliminates the need for expensive exotic materials by preventing thermal runaway conditions, thereby reducing manufacturing costs while maintaining adequate temperature range capability.
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 reduces the risk of overheating and catastrophic failure, enabling safer operation across a wider temperature range without the need for exotic materials, thus improving the efficiency and reliability of heat exchange processes.
Implementation Method 1
Heat is exchanged at the shell and tube heat exchanger between the first main flow and a flow of a hot shell-side fluid
Implementation Method 2
A first feed flow of a cool reactant is divided with a first control valve between a first main flow of the cool reactant and a first bypass flow of the cool reactant
Implementation Method 3
A temperature of the first combined flow is measured at or downstream of the first reactant outlet
Data Source
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AI summary
Temperature overshoot of internal components of a counter-flow shell and tube heat heat exchange may be reduced or avoided by adjusting the degree to which a tube-side fluid partially bypasses the heat exchanger.