What type of heat exchanger is most commonly used in power plants?

What type of heat exchanger is most commonly used in power plants?

• A. Direct Contact
• B. Shell and Tube
• C. Plate and Frame
• D. Crossflow

Answer: (B)

In power plants, heat exchangers must handle high pressures and temperatures, move large flow rates, and remain reliable and maintainable. The shell-and-tube design meets these demands by using a bundle of tubes inside a shell. One fluid flows through the tubes while the other travels around the tubes inside the shell, and you can arrange multiple passes to increase the temperature driving force and the overall heat transfer capacity. This setup provides a very robust pressure boundary, easy inspection and cleaning of the tubes, and the ability to handle different fluids and high duty services such as condensers, feedwater heaters, and boiler reboilers. Tubes can be replaced or repaired without rebuilding the whole unit, which is a big advantage for maintenance in a power plant. Direct contact exchangers mix streams, which is undesirable when you need to keep fluids separate and control temperatures precisely. Plate and frame exchangers offer high heat transfer coefficients in a compact form but are typically limited to lower pressures and temperatures and can be more challenging to scale up for very large plant duties. Crossflow describes a flow arrangement rather than a specific, large-scale, high-pressure heat exchanger design, so it’s not the standard choice for the primary heat transfer duties in power plants.

In power plants, heat exchangers must handle high pressures and temperatures, move large flow rates, and remain reliable and maintainable. The shell-and-tube design meets these demands by using a bundle of tubes inside a shell. One fluid flows through the tubes while the other travels around the tubes inside the shell, and you can arrange multiple passes to increase the temperature driving force and the overall heat transfer capacity. This setup provides a very robust pressure boundary, easy inspection and cleaning of the tubes, and the ability to handle different fluids and high duty services such as condensers, feedwater heaters, and boiler reboilers. Tubes can be replaced or repaired without rebuilding the whole unit, which is a big advantage for maintenance in a power plant.

Direct contact exchangers mix streams, which is undesirable when you need to keep fluids separate and control temperatures precisely. Plate and frame exchangers offer high heat transfer coefficients in a compact form but are typically limited to lower pressures and temperatures and can be more challenging to scale up for very large plant duties. Crossflow describes a flow arrangement rather than a specific, large-scale, high-pressure heat exchanger design, so it’s not the standard choice for the primary heat transfer duties in power plants.