Your plant is likely under constant pressure to increase efficiency and decrease operating costs. While shell-and-tubes are selected almost by default because they are a familiar technology, making the switch to plate heat exchangers — also known as compact heat exchangers — is a straightforward way to solve efficiency problems. The use of compact heat exchangers offers benefits in four areas:
- Energy Savings. Figure 1 shows the heat recovery level as a function of initial cost in a compact heat exchanger and a shell and tube. The yield from the compact heat exchanger can be up to 25 percent higher than for the shell and tube at a comparable cost. Shell-and-tube solutions with the same level of heat recovery may be more expensive than a compact heat exchanger.
- Less Maintenance. A highly turbulent flow makes compact heat exchangers less susceptible to fouling problems, resulting in long service intervals, increased operating time and more recovered heat.
- Increased Production. Compact heat exchangers may require less downtime for maintenance because operating intervals can be longer and the cleaning process may be faster.
- Installation Costs. Compact heat exchanger foundations can be made smaller and the units may be easier to fit into existing structures due to their compact design and lighter weight (figure 2).
When to Use Compact Heat Exchangers
Compact heat exchangers can be used in most industrial applications as long as design temperature and pressure are within the accepted range, which normally is up to 842°F (450°C) and 40 barg. When the application allows it, compact heat exchangers are good alternatives in situations when a high-grade, costly material is required for the heat exchanger; when a small footprint is an advantage; and when energy recovery is important.
Choosing the right compact heat exchanger can be a difficult and overwhelming task, but it should not be if you can answer some simple requirement questions. The chart above can guide you to a specific compact heat exchanger after you answer one question: Are gaskets at risk because of possible erosion with your gas or fluid? If you answer “yes,” then you will want to use the “welded” section of the chart. If no, you will want to use the “gasketed” section.
Types of Compact Heat Exchangers
There are many different types of compact plate heat exchangers to choose from, depending upon your process and application.
Semi-Welded Gasketed PHE
Semi-welded gasketed plate heat exchangers are for use in applications where it is difficult to find a compatible gasket such as acid and ammonia; and where there is less risk for leakage. This type handles most refrigerants on the welded side and is particularly suited for ammonia duties.
Fully Welded PHE
Fully welded plate heat exchangers are ideal for high temperature and high pressure applications.
Welded Circular Plate and Shell
The all-welded circular plate heat exchanger based on the plate-and-shell concept makes the welded plate-and-shell heat exchanger suitable for uses involving high pressures and temperatures.
Gasketed plate heat exchangers are used throughout the process industry as standard equipment for efficient heating, cooling, heat recovery, condensation and evaporation.
Wide-Gap Gasketed PHE
Wide-gap gasketed plate heat exchangers are used for general heating, cooling and heat recovery of media containing fibers and coarse particles. This type is also suitable for highly viscous fluids.
Double-Wall Gasketed PHE
This type of plate heat exchanger prevents fluids from intermixing and combines the high efficiency heat transfer benefits of conventional plates with a design that eliminates the risk of mixing.
Compact Welded Plate Bloc
An all-welded plate pack does away with all gaskets between plates and makes it possible to operate with a wide range of aggressive media and at high temperatures and pressures.
Fusion Bonded PHE
This is a 100 percent stainless steel, gasket-free alternative for industrial applications that use aggressive liquids as well as those in which there is a need for high efficiency, hermetically sealed PHEs.
Compactness and a self-cleaning design make spiral heat exchangers versatile. They are suitable for everything from dirty fluids to high vacuum condensation.