Welded Plate Heat Exchangers Bloc Type (Compabloc) features

 

While many process and maintenance engineers are familiar with the traditional gasketed plate heat exchanger, the welded plate heat exchanger has greatly expanded the appliable temperature and pressure rating available to the plate exchanger technology. The Compabloc welded plate heat exchanger has been used successfully for liquid-liquid, condensing, and reboiler duties. The Compabloc is one of the most flexible heat exchanger available and can often provide significant cost and installation savings over shell and tube heat and other style heat exchangers.

Beyond the Traditional Temperature and Pressure Ratings

Traditional gasketed plate heat exchangers find many applications in the Process Industries. However, with gaskets, they do have temperature and pressure limitation. These limitations are generally around 350 °F and up to 400 psig depending on the gasket material required. The Compabloc welded plate heat exchanger contains only compression style gaskets like those used on the heads of shell and tube style heat exchangers. The resulting temperature and pressure limitations are raised to in excess of 700 °F and 600 psig.

Figure 1: Exploded View of the Compabloc Welded Plate Heat Exchanger

The Compabloc welded plate heat exchanger is constructed by building stacks of rectangular plates into a heat transfer heart. These plates are edge welded to one another to form channels with 5 mm spacings. The liquids flow in cross flow to one another and each side can be configured into the needed number of passes to achieve the necessary heat transfer duty and pressure drop limitations. Each heat transfer "heart" is then mounted between four (4) carbon steel columns which contain stud bolts. The fluids are separated by column liners made of the same materials as the heat transfer plates. The top and bottom panel are carbon steel, but the fluids do not contact the heads as each head is separatef from the fluid by the first and last heat transfer plate in the plate pack. Finally, four (4) carbon steel panels containing the flanged connections are lined with the same materials as the heat transfer plates. The carbon steel panels are drilled along the edges to accept the stud bolts from the columns. All four (4) panels are assembled with compression gasekts to complete the construction. Figure 1 shows an exploded view of the completed Compabloc welded plate heat exchanger. The heat transfer plates can be made of any material which can be cold pressed including stainless steel, Titanium, SMO, Alloy C series metals, and others.

Figure 2: Mechanical Cleaning of a Compabloc Welded Plate Heat Exchanger

One of the setbacks that welded plate heat exchangers have experienced for years in the marketplace is that they were not accessible for mechanical cleaning. The Compabloc brings all of the advantages of the plate heat exchanger (higher heat transfer coefficients and minimal installation space) along with the ability to mechanically clean the heat exchanger. The four (4) carbon steel panels can be removed for access to the heat transfer heart. Water lancing the Compabloc is comparable to the same procedure used for shell and tube heat exchanger. In fact, the heat transfer core has a very short flow path versus a 6, 8, 12, or even longer heat transfer tube. Additionally, if you''re accustomed to chemically cleaning your heat exchangers, you can enjoy the additional benefit of the very low hold up volume of the Compabloc welded plate heat exchanger to minimize the amount of flow and chemical solution. The high degrees of turbulence in the unit make the chemical cleaning highly effective. Figure 2 shows a medium sized Compabloc undergoing mechanical cleaning.

The Compabloc welded plate heat exchanger can and has been used in a number of applications including:

• Coolers (Liquid-Liquid duties)
• Heaters (Liquid-Liquid duties)
• Condensers (Two-Phase duties)
• Subcoolers (Two-Phase duties)
• Reflux and vent condensers (Two-Phase duties)
• Forced circulation and thermosiphon reboilers (Two-Phase duties)

Figure 3 shows a Compabloc installed next to a shell and tube heat exchanger on an oil cooling duty. The Compabloc shown is actually performing 50% more heat transfer duty than the shell and tube heat exchanger installed next to it. Notice the savings in installation space. The Compabloc has special advantages in heating and cooling high viscosity fluids. Usually, on these types of duties, the overall heat transfer coefficient is limited on the side with the high viscosity fluid. The Compabloc allows you to take advantage of the plate type heat transfer coefficient on that side of the heat exchanger.

The Compabloc can be mounted both vertically (for liquid-liquid duties) or horizontally (for two-phase duties)

Figure 3: Compabloc vs. Shell and Tube Oil Cooler

. Figure 4 shows both the vertical and horiztonal installation configurations. The Compabloc excels as a condenser due to the ability to remove condensate along several points along the length of the plate as condensing occurs. This allows the vapor to be exposed to the cold plate surface. 

Figure 4: Vertical vs. Horizontal Installation Configuration

Figure 5 shows how condensate leaves the plate surface area.

Figure 5: Compabloc Plate Channel on a Condensing Duty

Another application where the Compabloc has been used widely is as a process interchanger. The ability to "cross temperatures" makes the Compabloc a superior choice versus shell and tube heat exchangers on interchanging duties. Where the shell and tube units may require seversal units in series, the Compabloc can utilize a single unit for the entire duty.

Figure 6: Compabloc as a Condenser / Subcooler in a Single Unit

The Compabloc can also be installed directly on the top of tanks for use as a reflux condenser. Additionally, while it''s common to use two different heat exchangers to condense and then subcool a liquid, this entire duty can easily be accomplished in a single Compabloc condenser. The ability to configure the pass arrangement to the needed duty makes this possible. Figure 6 shows a configuration for a Compabloc which was used in such a duty.

Another common use for a Compabloc is as a steam heater, especially when higher alloys are required. The Compabloc can be installed in the horizontal position and condensate level control is utilized to control the liquid side temperature. Compablocs have been used as reboilers and condensers on the same separation column.

Do you have a shell and tube heat exchanger that is causing a bottleneck in your system? Installing a Compabloc is series is a common method of debottlenecking a shell and tube heat exchanger, especially when floor space is at a premium.

Conclusions

The Compabloc heat exchanger is a very flexible heat exchanger which can be used to solve a wide variety of heat transfer problems. The ability to manufacture the heat transfer heart in many different materials of construction, the low heat transfer area required, minimal installation space needed, and flexibility to configure the pass arrangement as needed lend the Compabloc to many different applications in many different industries. Now, you can have a welded plate heat exchanger that you can clean, and you''ll never have to replace gaskets between the heat transfer plates. Consider the Compabloc welded plate heat exchanger for your next application.

Credits

http://www.virginiaheattransfer.com/content/heat-transfer/compabloc-heat-exchanger