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End User Outlook
2.4 Heat exchanger type selection Different heat exchanger designs, such as Tubular Exchanger Manufacturers Association( TEMA) standards, offer specific advantages. For instance, TEMA C-type exchangers are preferred for hightemperature, high-pressure applications because of their reduced likelihood of leakage, compared to TEMA B-types. TEMA D-types with screw plug exchangers allow for custom arrangements and easier maintenance.
2.5 Safety and reliability Startup and shutdown conditions often subject heat exchangers to rapid changes in temperature, causing thermal stresses. The use of rupture disks and other pressure-relief devices can prevent catastrophic failures in the event of overpressure.
Possible solutions 3.1 Use of appropriate design temperatures Designing heat exchangers with different temperatures for various components can significantly reduce material costs and improve efficiency. Instead of designing all components for the maximum operating temperature, parts like pass partition boxes, tubes, and channel covers can be engineered for lower temperatures where possible. Similarly, hot and cold tubesheet can be designed with different temperature tolerances, optimizing material usage without sacrificing safety.
Temperature variation throughout the body of a heat exchanger.
Haynes 282, and Sanicro 25 due to their high mechanical strength, resistance to oxidation, and ability to withstand thermal cycling. These materials, while more expensive, significantly outperform conventional carbon steels in high-temperature environments. For example, Inconel 625 retains its mechanical properties up to 700 ° C, making it a popular choice for heat exchangers used in chemical and nuclear applications.
2.2 Thermal expansion management When designing for high-temperature applications, different materials exhibit varying levels of thermal expansion. To mitigate this, designers often use U-tubes or floating heads, which allow components to expand without causing mechanical stress. Expansion joints are another solution that absorbs thermal expansion without introducing stress into the system.
2.3 Gasket and sealing technology One critical factor in high-pressure systems is minimizing the risk of leakage. The use of welded joints instead of gasketed joints is recommended for high-pressure environments. Welded diaphragms or expansion bellows can further reduce the risk of leakage while maintaining flexibility in the system.
3.2 Metallurgy of components The selection of materials for heat exchangers operating at high temperatures is vital for their longevity and performance. Nickel-based alloys such as Inconel 740H and Haynes 282 offer excellent strength and oxidation resistance at temperatures up to 800 ° C. Ferrous alloys, such as stainless-steel grades 316 and 347H, are also widely used for lower temperature applications due to their cost-effectiveness. Hastelloy is frequently used when chemical aggressiveness and high temperatures are combined, as it can resist extreme corrosion while maintaining mechanical integrity.
3.3 Design at differential pressure Heat exchangers operating under differential pressure scenarios often experience lower pressure gradients compared to the maximum operating pressures of individual fluids. For example, a tube side operating at 100 bar and a shell side at 90 bar create a differential pressure of just 10 bar. Designing for the differential pressure, rather than the full pressure, significantly reduces the required tube wall thickness, lowering material costs and weight while preserving safety margins.
Case study 4.1 Advantages of using differential design temperatures for heat exchanger components In high-temperature, high-pressure heat exchangers, the use of uniform design temperatures across all components can lead to excessive material costs and increased equipment thickness, as each component is designed to withstand the highest potential temperatures. However, by applying different design
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