Titanium Heat Exchanger Tubes for Low-Temperature Waste Heat Recovery
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Heat exchange tubes in boiler systems are prone to corrosion from sulfuric acid, limiting waste heat recovery, and cannot be welded due to thermal deformation, which affects the efficiency and durability of heat exchangers.
Innovation Solution
The use of titanium heat exchange tubes, which are corrosion-resistant to sulfuric acid, and a tube expansion method for fastening instead of welding to prevent distortion, allowing for effective waste heat recovery even at low temperatures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional heat exchange tubes are used in boiler exhaust systems, then the system structure is simple and manufacturing is easy, but the tubes are corroded by sulfuric acid in exhaust gas, reducing lifespan and limiting waste heat recovery at low temperatures
Solution Approach 1:
The patent changes the material parameter from conventional steel to titanium, which fundamentally alters the chemical properties to resist sulfuric acid corrosion. This material substitution enables waste heat recovery at temperatures below 170°C without corrosion damage, while the joining method parameter is changed from welding to mechanical expansion to accommodate titanium's properties.
Solution Approach 2:
The patent replaces the welding process (thermal-mechanical system) with a mechanical expansion system. The expansion machine mechanically expands the tube ends to fit into the side plate holes, creating a secure connection without thermal input. This substitution eliminates the thermal deformation problem inherent in welding titanium while maintaining connection reliability.
2Strength
If welding is used to fasten heat exchange tubes to side plates, then the connection is strong and reliable, but titanium tubes undergo thermal deformation and distortion during welding, compromising structural integrity
Solution Approach 1:
The patent replaces the welding process (thermal-mechanical system) with a mechanical expansion system. The expansion machine mechanically expands the tube ends to fit into the side plate holes, creating a secure connection without thermal input. This substitution eliminates the thermal deformation problem inherent in welding titanium while maintaining connection reliability.
Solution Approach 2:
The patent performs preliminary preparation by creating expansion holes in the side plates with specific dimensions before tube installation. The holes are designed to accommodate the tube outer diameter, allowing the expansion process to proceed smoothly and achieve the desired interference fit without excessive force or misalignment, thereby maintaining dimensional accuracy.
3Reliability
If exhaust gas temperature is maintained above 170°C to prevent low-temperature corrosion, then the heat exchange tubes are protected from corrosion, but waste heat recovery efficiency is reduced due to higher discharge temperature
Solution Approach 1:
The patent changes the material parameter from conventional steel to titanium, which fundamentally alters the chemical properties to resist sulfuric acid corrosion. This material substitution enables waste heat recovery at temperatures below 170°C without corrosion damage, while the joining method parameter is changed from welding to mechanical expansion to accommodate titanium's properties.
Solution Approach 2:
The patent converts the previously harmful low-temperature exhaust gas (which caused corrosion in conventional systems) into a beneficial resource. By using corrosion-resistant titanium tubes, the system can now safely operate at lower temperatures, turning what was once a harmful condition into an opportunity for improved heat recovery efficiency and reduced energy loss.
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 solution prevents corrosion and maintains uniform thermal efficiency, enabling the recovery of waste heat at temperatures below 170°C, reducing fuel consumption and improving heat exchange efficiency.
Implementation Method 1
waste heat can be recovered through heat exchange between high-temperature exhaust gas at a temperature of 200-250°C and cold water at a temperature of about 10-15°C in a counter-flow manner
Implementation Method 2
The heat exchange tubes are fastened to the first side plate by inserting the first ends thereof into the first side through holes and expanding the first ends, and are fastened to the second side plate by inserting the second ends thereof into the second side through holes and expanding the second ends
Data Source
Figure 1
Figure 2
Figure 3~4
AI summary
Disclosed herein is a heat exchanger for the recovery of waste heat. The heat exchanger includes: a bottom plate configured such that an exhaust gas inlet is formed therethrough; a top plate configured such that an exhaust gas outlet is formed therethrough at a location opposite that of the exhaust gas inlet; a first side plate configured such that a plurality first side through holes is formed therethrough; a second side plate configured such that a plurality of second side through holes is formed therethrough at locations opposite those of the first side through holes; a third side plate and a fourth side plate configured to connect the first side plate and the second side plate; and a plurality of heat exchange tubes formed as titanium material tubes, and configured to connect parallel between the first side through holes and the second side through holes.