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End User Outlook
Emerging technologies: design innovation for high-temperature and pressure heat exchangers
Industries such as oil and gas, fertilizer, and chemical processing manage operations that occur within extreme temperature and pressure conditions. These severe conditions pose significant challenges to the equipment’ s design, fabrication, and maintenance. Heat exchangers are one of the most important parts of these processes, and they are essential for efficient thermal management. Conventional approaches to designing and operating heat exchangers under these conditions can lead to catastrophic failures. This article discusses the various challenges associated with heat exchangers that operate at high temperatures and high pressures and provides various design solutions for heat exchangers operating above ~ 300 ° C and ~ 70 bar( g).
By Rashik Bansal – Sr. Technical Professional Leader, Arjun Gupta – Associate Technical Professional, Sonali Padhi – Associate Technical Professional,- KBR
Failure complexity maintenance.
Manufacturers continue to face difficulties with malfunctions during operation despite the widespread use of heat exchangers. With increasing severity of operations, heat exchangers face many problems that may affect their effectiveness, including corrosion, fouling, and temperature gradient 1. These phenomena occur at high temperatures, rapidly decreasing the lives of heat exchangers. Studies show that at the steam inlet temperature of 649 ° C the heat exchanger’ s effectiveness dropped to 62 % 2. Fouling is another significant phenomenon that occurs when the temperature in the system increases, especially with compact heat exchangers 3. Traditional aluminum plate and frame heat exchangers( PFHE) have an operating temperature of less than 200 ° C and can tolerate pressures of up to 12 MPa. The maximum temperature and pressure restrictions for employing a PFHE with stainless steel are around 800 ° C and 8 MPa, respectively 4. Material selection is also critical in ensuring that components can withstand thermal and mechanical stresses without degradation over time. Leakage is another challenge with high pressure heat exchangers. Samantray, J. S., et al. observed a leakage rate of 0.7 % on the shell side for an exchanger operating at 132 bar of shell side pressure 5.
Challenges 1.1 Challenges associated with high temperature A number of physical phenomena impact the integrity and efficiency of heat exchangers that are subjected to high temperatures, including materials that become softer and lose mechanical strength after exposure. Materials that are not made to resist
Common failures associated with high-temperature and pressure heat exchangers.
thermal expansion and frequent thermal cycling are especially vulnerable to this. When heated to high temperatures, metals undergo thermal expansion, which can cause changes to dimensions and create stresses. Creep is the gradual deformation of materials caused by continuous tension at high temperatures. Heat exchangers are especially vulnerable to thermal strains when there are temperature gradients across their surfaces. Rapid temperature changes that occur, particularly at startup or shutdown, invite stresses that may cause cracking and deformation. Heat exchangers experience fouling and scaling more at higher temperatures than at lower temperatures, which decreases the heat transfer surfaces and lowers efficiency. Frequent maintenance in such cases is necessary. Stream leakage is more likely to occur at high temperatures because the components expand at joints and gaskets.
16 Heat Exchanger World April 2025 www. heat-exchanger-world. com