Integrated Heat Exchanger for Oxygen Preheating
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Solution Overview
Problem
Existing methods for preheating oxygen in industrial combustion processes are limited by high costs and space requirements, and are not optimized for conditions outside nominal operation, leading to inefficient energy recovery and increased fuel consumption.
Innovation Solution
A process that recovers residual heat from flue gases by heating an auxiliary gas in a first heat exchanger and then using a portion of this hot gas to preheat the oxidant in a second heat exchanger, allowing for increased thermal energy content and flexibility in thermal energy recovery.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If indirect preheating of oxygen is used with auxiliary exchanger and main heat exchanger, then safety is improved and energy recovery is enhanced, but space requirements and installation costs increase
Solution Approach 1:
The patent combines the auxiliary exchanger and main heat exchanger into a single integrated heat exchanger unit. The heat exchanger has a first heat exchange zone for preheating oxygen-rich oxidizer and a second heat exchange zone for preheating poorer oxidizer, merging multiple heating functions into one device, thereby reducing space requirements while maintaining safety and energy recovery benefits
Solution Approach 2:
The single heat exchanger performs multiple functions: it preheats oxygen-rich oxidizer in the first zone and poorer oxidizer in the second zone simultaneously. This multi-functional design eliminates the need for separate auxiliary and main exchangers, reducing installation space and complexity while preserving the energy recovery advantages
2Loss of energy
If indirect preheating method is implemented, then energy recovery efficiency is improved, but installation complexity and cost increase
Solution Approach 1:
The patent merges the auxiliary exchanger and main heat exchanger into a single integrated unit with distinct heat exchange zones. This consolidation maintains the two-stage preheating process that efficiently recovers energy from flue gases while reducing the number of separate components, thereby lowering installation complexity and cost
3Area of stationary object
If flue gases are used directly for preheating, then space requirements are reduced, but safety risks increase due to potential contact between hot flue gases and oxygen
Solution Approach 1:
The heat exchanger is segmented into at least two distinct heat exchange zones: a first zone where oxygen-rich oxidizer is preheated by flue gases, and a second zone where poorer oxidizer is preheated. This segmentation ensures that oxygen and hot flue gases never come into direct contact, maintaining safety while using a compact single-unit design that reduces space requirements
Solution Approach 2:
The heat exchanger structure acts as an intermediary between flue gases and oxidizer streams. Heat is transferred through the heat exchanger walls from flue gases to the oxidizer streams in controlled zones, preventing direct contact between hot flue gases and oxygen while enabling efficient thermal energy transfer in a compact configuration
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 the efficiency of heat exchanges without increasing costs, allows for greater thermal energy recovery, and compensates for reduced efficiency due to aging or increased heat requirements, maintaining safety by keeping the hot flue gas content low in the heat-exchange gas.
Implementation Method 1
heating an auxiliary gas by heat exchange, in a first heat exchanger, with at least a part of the discharged hot flue gases
Implementation Method 2
preheating, in a second heat exchanger, the oxidant by heat exchange with a heat-exchange gas comprising at least a first part of the hot auxiliary gas
Data Source
AI summary
Combustion method and installation in which an oxygen-rich oxidant is preheated by exchange of heat with a heat-transfer fluid, upstream of the combustion chamber, in which method and installation an auxiliary gas is heated by heat exchange with a first proportion of the hot flue gases discharged from the chamber, and in which method and installation the heat-transfer fluid comprises a mixture of at least a proportion of the heated auxiliary gas with a proportion of hot flue gases.