Heat Exchangers on Ships

Heat exchangers are a kind of thermal machine widely employed on ships of every type, from cruise ships to large commercial ones, where they provide cooling of engines and hydraulic oil, in order to ensure the perfect lubrication and working conditions of each transmission and power system on board.

These heat exchangers can work using sea water largely available, exploiting the cooling temperature offered, but requiring on the other hand special materials to be employed for the construction, such as titanium, a corrosion resistant material in salty seawater, and other issues related to clogging and scaling due to the presence of micro-organisms.

Tempco has been recently contacted by the maintenance office of a marine-shipping company regarding a problem in the performance of plate heat exchangers installed in the power engine room of a merchant ship. In such cases, our service department proceeds to ask various for information from the customer in order to identify the kind of the problem:

  • Project thermal performances
  • Project workloads
  • Kind of heat exchanger
  • Kind of involved fluids

Software simulation allows to exactly identify the problem: in this case, the marine heat exchanger was severely clogged, avoiding to reach optimal design performances to ensure right working conditions during navigation.

Once the plate model was established, we prepared a whole new titanium plates pack ready for installation: titanium is indeed the most suitable constructing material for salty seawater applications.

Substitution was done very quickly, our service team stepped in while the ship was in harbor stop, and during a half day the heat exchanger was reconditioned: the old Alfa Laval plates pack has been removed and substituted by the new one, totally compatible and interchangeable, and the very next day the ship was able to sail again. The old plates pack was then brought to our technical department for a complete cleansing and regeneration, allowing the customer to dispose in the future of a fully functioning spare plates pack.

The whole operation was fulfilled in one and a half working day, including on-site transfer and testing of the reconditioned heat exchanger, not requiring connections dismantle neither to remove the heat exchanger from the engine room. This kind of operation can only be achieved in applications using plate heat exchangers, and this kind of reconditioning, substitution and possible strengthening operations can be performed on plate exchangers of different and several brand and manufacturers:

  • Alfa Laval
  • Gea Ecoflex
  • APV
  • Schmidt
  • Tranter
  • Swep

Plate heat exchangers are indeed today an excellent and totally valid alternative to traditional shell and tube heat exchangers, thanks to the latest evolution that allows to cover an always wider range of applications, covering more and more higher temperature and pressure conditions. It also allows to take advantage of benefits offered by plate heat exchangers, compared to classic shell and tube type, such as:

  • Higher efficiency
  • More compact design
  • Higher flexibility

While shell and tube heat exchangers are still the unique solution for heat recovery in gasification process on refinery waste in petrochemical plants, and generally in all extreme applications such as waste fumes or low pressure air recovery (involving issues for load losses and speed), in recent years the application range for plate heat exchangers has indeed incredibly increased.

With brazed plates first, and then also with all welded type, working pressure and temperature limits were lifted very much: so that today is not difficult to find always more applications in several industrial processes, employing plate heat exchangers with pressures over 50bar and temperatures of 350°C. The extreme limit reachable with this kind of heat exchangers is quite easily 900°C, with pressures up to 100bar, and below these values there are obviously many applications successfully allowing the employ of plate heat exchangers.

In addition, modern technology affords cold stamping of stainless steel, the less ‘precious’ material that can be employed with this kind of exchangers, with always decreasing thickness, without compromising resistance to differential pressure values.
Choosing a plate heat exchanger also offer to satisfy current needs of miniaturization and compact design in plants, saving on water consumption and, as the naval case history above reports, a plate heat exchanger can be modified and improved directly on-site, simply increasing thermal transfer surface adding new plates, without changes required on piping that would be necessary in case of a shell and tube exchanger.

Aiming to offer a full custom standard flexibility, meaning for Tempco the effort to engineer and offer standard products easily customisable on various and more and more specific needs of customers everywhere, plate heat exchangers are today the most useful and flexible solution to solve any kind of thermal energy management issue and heat recovery in any kind of industrial process, not only for cooling applications on ships in the marine sector.

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