**2. Longitudinal type heat exchanger technology**

Conventional S&T heat exchangers, widely used in Oil&Gas, Petrochemical, Chemical and Power Plants, are of the "segmental baffle" type, where the baffles support the tubes and govern the cross/longitudinal ratio of the shell flow direction through the bundle. The turbulent motion originated by the cross direction, normal to the exchanger tubes, determines the shell side heat transfer coefficients (HTC), that in many configurations controls the global value, and the consumed pressure drops. Decades of operational experience led to a widespread know-how in design and manufacture of safe, high performing and long-life segmental baffles heat exchangers, driving, at the same time, to claim for alternate design concepts in order to overcome the few critical limits of the technology.

Two matters in particular have been deeply addressed, depending on process flow rates and fluid nature (clean or dirty) [1, 2]:

• potential vibrations, induced by the cross component of high flow rates, may affect the exchanger tubes reliability;

confinement but taking care at the same time of the heat transfer performance have

Aiming to grant all tubes confinement at any individual baffle, the EMbaffle® longitudinal flow type heat exchanger was then conceived and developed. Rods and strips are replaced by a patented Expanded Metal grid, (that's where EMbaffle name comes from). By making best use of the available shell side pressure drops, the unsupported tubes span can be easily managed to design the most stiff cage solution

Initially thought to eliminate the dead areas in fouling applications, the grid geometries and baffles span impacts on fluid flow paths have been progressively explored, by both CFD analysis and experimental measurements, to establish design criteria aimed to maximize the shell side HTC making best use of the available pressure drops. Two significant improvements in the longitudinal baffle technology are so

• Tubes full support at any baffle makes the technology ready to replace the Rod Baffle and "No Tube in the window" TEMA designs in most applications where

today available in the S&T heat exchangers market (**Figure 2**).

*EMbaffle® design – One baffle fully supporting each individual tube.*

been developed.

**Figure 1.**

achieved:

**Figure 2.**

**327**

**3. EMbaffle® development**

*Longitudinal vs. conventional S&T heat exchanger.*

*EMbaffle® Heat Transfer Technology Step-Up in CO2 Reduction*

*DOI: http://dx.doi.org/10.5772/intechopen.96253*

• the flow recirculation, at the dead areas formed by the baffle outer diameter with the shell inner diameter, may induce, with dirty fluids, to progressive fouling accumulation, thus reducing the heat transfer surface and leading to potential tube local overheating and corrosion issues.

Further, the lowest design temperature approach, (typical for example of the very few degrees in Power generation pre-heaters), is limited because of the cross-flow component.

Helical and pure longitudinal flow design concepts have been exploited and exchangers have been developed to overcome some of the above criticalities.

In longitudinal flow solutions, design aims to reduced, up to the total suppression, the dead areas and the cross-flow component of a non-cross type Shell&Tube exchanger (**Figure 1**). The associated reduced drift and hydraulic resistance lead to significantly reduced pressure drops and the reduced span of tubes support elements grants a bundle compact assembly preventing potential vibration phenomena.

Among the longitudinal flow type heat exchangers, the Rod-Baffle is the pioneer. Conceived to suppress vibration issues by reducing the baffles span in shell side high flow rate and pure cross flow applications, in this technology, the tubes are supported by a repeated series of four regularly spaced-apart rod lines welded to a peripherical ring. The rod lines are disposed in alternate horizontal and vertical directions (one set of parallel rod lines at any single baffle), to form a square support, so that four baffles are required to fully confine the tube. The large free flow area left by the baffle determines a pure-like longitudinal flow in non-cross flow type HE.

It is the intent of this technology to govern a low value of pressure drops to suppress vibrations, accepting the resulting total Heat Transfer Coefficient as a consequent outcome.

Rod baffle basic concept was initially replicated by making use of strips in place of rods; only more recently solutions aimed to further reinforce the tubes

*EMbaffle® Heat Transfer Technology Step-Up in CO2 Reduction DOI: http://dx.doi.org/10.5772/intechopen.96253*

#### **Figure 1.** *Longitudinal vs. conventional S&T heat exchanger.*

The following paragraphs describes this technology, from general features to its

Finally some technical advancements are reported, together with some design cases related to services where EMbaffle® technology proves its advantages over

Conventional S&T heat exchangers, widely used in Oil&Gas, Petrochemical, Chemical and Power Plants, are of the "segmental baffle" type, where the baffles support the tubes and govern the cross/longitudinal ratio of the shell flow direction through the bundle. The turbulent motion originated by the cross direction, normal to the exchanger tubes, determines the shell side heat transfer coefficients (HTC), that in many configurations controls the global value, and the consumed pressure drops. Decades of operational experience led to a widespread know-how in design and manufacture of safe, high performing and long-life segmental baffles heat exchangers, driving, at the same time, to claim for alternate design concepts in

Two matters in particular have been deeply addressed, depending on process

• potential vibrations, induced by the cross component of high flow rates, may

• the flow recirculation, at the dead areas formed by the baffle outer diameter with the shell inner diameter, may induce, with dirty fluids, to progressive fouling accumulation, thus reducing the heat transfer surface and leading to

Further, the lowest design temperature approach, (typical for example of the very few degrees in Power generation pre-heaters), is limited because of the

Helical and pure longitudinal flow design concepts have been exploited and exchangers have been developed to overcome some of the above criticalities.

the dead areas and the cross-flow component of a non-cross type Shell&Tube exchanger (**Figure 1**). The associated reduced drift and hydraulic resistance lead to significantly reduced pressure drops and the reduced span of tubes support elements grants a bundle compact assembly preventing potential vibration phenomena.

flow rate and pure cross flow applications, in this technology, the tubes are supported by a repeated series of four regularly spaced-apart rod lines welded to a peripherical ring. The rod lines are disposed in alternate horizontal and vertical directions (one set of parallel rod lines at any single baffle), to form a square support, so that four baffles are required to fully confine the tube. The large free flow area left by the baffle determines a pure-like longitudinal flow in non-cross flow type HE. It is the intent of this technology to govern a low value of pressure drops to suppress vibrations, accepting the resulting total Heat Transfer Coefficient as a

of rods; only more recently solutions aimed to further reinforce the tubes

In longitudinal flow solutions, design aims to reduced, up to the total suppression,

Among the longitudinal flow type heat exchangers, the Rod-Baffle is the pioneer. Conceived to suppress vibration issues by reducing the baffles span in shell side high

Rod baffle basic concept was initially replicated by making use of strips in place

inherent advantages, pressure drop and heat transfer characteristics.

**2. Longitudinal type heat exchanger technology**

*Heat Transfer - Design, Experimentation and Applications*

order to overcome the few critical limits of the technology.

potential tube local overheating and corrosion issues.

flow rates and fluid nature (clean or dirty) [1, 2]:

affect the exchanger tubes reliability;

cross-flow component.

consequent outcome.

**326**

conventional segmental exchangers.

confinement but taking care at the same time of the heat transfer performance have been developed.
