**10. EMbaffle® design cases**

approach is therefore not only the increased heat recovery but also prolonged exchanger operating time through the reduction of fouling progress on both shell

*Heat Transfer - Design, Experimentation and Applications*

For applications such as LNG vaporization, the combination between EMbaffle® and tube inserts is expected to be quite effective. On shell side, the EMbaffle® open structure will prevent the formation of dead zones guaranteeing, with the selection of proper grids span, the required tubes support, while inserts can mitigate the vaporizing issues at tubes inner surface by increasing the radial mixing.

the performance between the use of bare tubes with finned tubes.

ment and test center in Europe for molten salt application in CSP.

displacement of finned tubes in the most stringent conditions.

resistances to maintain a temperature constantly above 380 °C.

support points of the baffle grid diamond.

is of extreme importance.

**340**

A test campaign was carried out on the molten salt/thermal oil case to compare

A heat exchanger based on EMbaffle technology with finned tubes was installed at the Concentrating Solar Platform centre in Almeria (Spain), the largest develop-

A test campaign was carried out using molten salt and thermal oil as media. A comparison has been made between the field test and an equivalent plain tube case

Results shows an average 8% reduction in the overall heat transfer resistance. The consequent increase in performances is significant, even if not so high in absolute value: application of low fin tubes for this process shall be carefully

The use of baffles made with "metal grid" instead of the more common "metal plate" suggests the need to verify their mechanical strength characteristics, especially in cases finned tubes are used and in the presence of processes with repeated

The different temperature distribution between the bundle support cage and the tubes during thermal transient brings to sliding of the tube inside the grid mesh, which could result mechanically harmful especially in the case of finned tubes. In addition to the FEA for checking the static and dynamic stresses due to the accelerations induced on the tubes and on the grid, an experimental test was carried out to verify the consequences onto the grid subjected to the periodic longitudinal

Two vertical baffles were positioned inside a horizontal cylindrical chamber and

a finned tube was passed through them; weight and dimensions of tube were representative of the real exchanger conditions. A servomotor and a screw-nut type transmission were used to move the tube by operating a mechanical arm designed to transfer only a horizontal movement, minimizing any vertical thrust. The cylindrical chamber was filled with molten salts kept liquid with a system of heating

Horizontal oscillatory movements (5 mm) equivalent to a 10-years working period of a exchanger with two daily transients were simulated to evaluate the effects of the relative wearing between the exchanger tube fin diameter and contact

At the end of the test period the measurements of the outer diameter of the finned surface did show variation in height of the fins within 5% while no evidence of surface defect was registered on the contact profile of the grid mesh. Such a result

and tube sides.

**9.2 Oil to molten salts in CSP**

calculated with the correlations.

**9.3 Mechanical performance test**

evaluated.

thermal transients.

Few design cases are presented in this paragraph as examples of how the application of EMbaffle® technology brings evident benefits.

#### **10.1 DesignCase-1: overhead gas cooler**

Two identical units (each one with two exchangers in parallel) have been installed in a platform. Using Sea water, the Overhead Gas Coolers were designed to cool high pressure acid natural gas from 110 °C down to 33 °C.

For this process the temperature approach between the fluids dictated a pure countercurrent arrangement, and the high water flow rate on the shell side did not allow the use of an F-shell TEMA type. Consequently a conventional segmental design in this case would have resulted in a much bigger and not-optimized geometry. A single pass for both tube and shell side exchanger would have been applied, with straight tubes and two tube sheets per exchanger.

The very limited shell-side available pressure drop in combination with the ability to accommodate large flow rates made this application very suitable for EMbaffle®, making possible the use of a F-shell TEMA type (**Figure 20**). The result was an optimized design, able to achieve a pure counter current arrangement with the application of U-tubes, which granted a single tube sheet per exchanger, reducing the weight. During the design stage a higher OHTC has been also exploited, with a consequent reduction in required heat transfer surface. Given the off-shore application, the reduction in size and weight obtained for the exchangers was particularly beneficial.

**Figure 20.** *EMbaffle® overhead gas cooler.*


**Table 1.**

*Design comparison between EMbaffle® and conventional S&T for an overhead gas cooler.*

**Table 1** reports a comparison between a conventional S&T exchanger and the EMbaffle® type exchanger for this case.

**10.3 CO2-based power generation plants**

production plants one of the most promising.

*Basic regenerative Brayton cycle for CO2-based power production plant.*

source medium.

**Figure 22.**

**343**

**Table 2.**

Challenge to avoid/reduce emission of carbon dioxide in power generation industry has been addressed in many ways, being its use as working fluid in power

*Design comparison between EMbaffle® and a conventional S&T for a cycle gas cooler.*

**Cycle Gas Cooler Conventional design EMbaffle® design** *Units TEMA type* BEM [8] BEM [8] *— Number of equipments* 2 in parallel 1 *— Shell ID* 1740 1800 *mm Tube length* 9760 11200 *mm Baffle arrangement* NTIW EMbaffle *— Installed area* 3173 2335 *m2 SS pressure drop* 0.7 0.7 *bar Duty* 69400 69400 *kW Duty / Installed area* 21.9 29.7 *kW/m2 Weight* 126.6 79.2 *tons*

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

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

**Table 3** reports a comparison between technologies for Gas Regenerator.

**Figure 22** illustrates the supercritical Brayton-cycle and the relevant heat transfer units. High pressures involved and typically large gas flow rates may suggest adoption of S&T heat exchanger, being EMbaffle® one of the promising layout in consideration of the benefits envisaged in Gas Treatment and Purification chapter. Technology usually proves either as Gas Regenerator (path 2–3, 5–6), even in consideration of typical low temperature approach and pure countercurrent layout, and Gas Cooler (path 6–1); whereas large compression factors have to be achieved multistage Gas Intercoolers (not represented in the figure, along the path 1–2) are adopted. Depending on the application, Gas Heater design may rely on S&T layout or onto other piece of equipment (WHRU as example) depending onto the heat

The improvement described above are clearly depicted: EMbaffle® design is able to exploit the same duty of the conventional case with a 25% reduction of the installed surface area, providing the same shell-side pressure drop.

#### **10.2 DesignCase-2: cycle gas cooler**

**Figure 21** depicts a Cycle Gas Cooler, installed in a large chemical plant in North America. The function of the exchanger is to use Cycle water to cool the hot gas (placed at the tube side) from 100 °C to 40 °C.

Water flow rate was huge (more than 4000 tons per hour) and simply could not be accommodated in a single conventional baffle equipped heat exchanger. Two conventional units operating in parallel would have been necessary in order to guarantee a vibration-free design.

From the pressure drops point of view also, the single conventional unit would not have been an option resulting in pressure drops far above the allowable ones. In **Table 2** the straight comparison between the two designs is reported.

**Figure 21.** *EMbaffle® cycle gas cooler.*


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

**Table 2.**

**Table 1** reports a comparison between a conventional S&T exchanger and the

**Overhead Gas Cooler Conventional design EMbaffle® design** *Units TEMA type* BEM [8] BFU [8] *— Number of equipments* 2 in parallel 2 in parallel *— Shell ID* 1780 1610 *mm Tube length* 10000 7315 *mm Baffle arrangement* NTIW EMbaffle *— Installed area* 3530 2609 *m<sup>2</sup> SS pressure drop* 0.3 0.3 *bar Duty* 50800 50800 *kW Duty / Installed area* 14.4 19.5 *kW/m<sup>2</sup> Weight* 118.2 73.3 *tons*

The improvement described above are clearly depicted: EMbaffle® design is able to exploit the same duty of the conventional case with a 25% reduction of the

**Figure 21** depicts a Cycle Gas Cooler, installed in a large chemical plant in North America. The function of the exchanger is to use Cycle water to cool the hot gas

Water flow rate was huge (more than 4000 tons per hour) and simply could not be accommodated in a single conventional baffle equipped heat exchanger. Two conventional units operating in parallel would have been necessary in order to

From the pressure drops point of view also, the single conventional unit would not have been an option resulting in pressure drops far above the allowable ones. In

installed surface area, providing the same shell-side pressure drop.

*Design comparison between EMbaffle® and conventional S&T for an overhead gas cooler.*

**Table 2** the straight comparison between the two designs is reported.

EMbaffle® type exchanger for this case.

*Heat Transfer - Design, Experimentation and Applications*

**Table 1.**

**Figure 21.**

**342**

*EMbaffle® cycle gas cooler.*

**10.2 DesignCase-2: cycle gas cooler**

guarantee a vibration-free design.

(placed at the tube side) from 100 °C to 40 °C.

*Design comparison between EMbaffle® and a conventional S&T for a cycle gas cooler.*

#### **10.3 CO2-based power generation plants**

Challenge to avoid/reduce emission of carbon dioxide in power generation industry has been addressed in many ways, being its use as working fluid in power production plants one of the most promising.

**Figure 22** illustrates the supercritical Brayton-cycle and the relevant heat transfer units. High pressures involved and typically large gas flow rates may suggest adoption of S&T heat exchanger, being EMbaffle® one of the promising layout in consideration of the benefits envisaged in Gas Treatment and Purification chapter. Technology usually proves either as Gas Regenerator (path 2–3, 5–6), even in consideration of typical low temperature approach and pure countercurrent layout, and Gas Cooler (path 6–1); whereas large compression factors have to be achieved multistage Gas Intercoolers (not represented in the figure, along the path 1–2) are adopted. Depending on the application, Gas Heater design may rely on S&T layout or onto other piece of equipment (WHRU as example) depending onto the heat source medium.

**Table 3** reports a comparison between technologies for Gas Regenerator.

**Figure 22.** *Basic regenerative Brayton cycle for CO2-based power production plant.*
