Koninklijke Vereniging - Société Royale



Why not use waste heat?

At a meeting of IMarEST’s UAE branch held towards the end of last year, Copenhagen- based Bawat introduced a patented system that represents arguably the simplest technology to treat ballast water.

This is claimed to be a unique system that does not interrupt revenue earning cargo operations, does not need UV, filters or chemicals and optimises energy efficiency by exploiting the engine’s waste heat. It also complies with the IMO D2 performance standard.

At the meeting, Klaus Andreasen, Bawat senior sales manager, claimed that this BWMS represents a breakthrough technological advance in ballast water treatment. This in-voyage system ensures zero impact on ship performance and zero disruption to cargo and ballast operations while the vessel is in port.

Bawat’s BWMS is based on pasteurisation with no use of chemical compounds, UV-radiation or filters. Pasteurisation is a combination of heat and time and is a widely used process in the food industry, he explained.

Ballast water is pumped through a pasteurising unit, consisting of plate heat exchangers and a retention tank. When passing through the pasteurisation unit, the ballast water is heated and kept, while still in flow, within a retention section for up to about 75 seconds, depending of the pasteurising temperature.

The heating takes place in one or two plate heat exchangers and the heat is provided by on board surplus heat sources – eg, main engine jacket cooling water or exhaust heat.

Following pasteurisation, the ballast water passes through the regeneration section, acting as a pre-heater of the incoming ballast water, and cooler for the outgoing ballast water, taking the temperature down to four to seven degrees higher than the inlet temperature.

When the ballast water has been treated in the pasteurising unit it fulfils the Ballast Water Conventions outlet criteria to both USCG and IMO’s way of testing methods. No holding time or retreatment is necessary. There are no filters used in the process, neither is chemical use required.

Since the water fulfils the Ballast Water Convention’s outlet criteria when treatment in the pasteurising unit is completed, it gives the opportunity to treat the water in four separate ways. Using pasteurisation for water treatment avoids the risk of toxicity to both the environment and humans.

Andreasen emphasised the economic advantages for shipowners, for example, flexibility in offering four different treatment options in the same system, and adaptable to any ship size.

Containerised system

As an alternative quick response to fixed on board systems, Bawat has developed a containerised BWTS. This offers an onshore mobile treatment service to shipowners for water treatment at ports and terminals.

In addition, this mobile solution could be used as a backup service for ports aimed at ship’s which are unable to discharge treated water. Shipyards could also see a mobile solution as an opportunity to treat ballast water from docked ships.

The mobile solution includes heat recovery, no use of consumables and with no end residue for treatment.

Andreasen explained that for tankers, X-proof was not an issue as equipment can be fitted in any location on board. The question is - how to get the heat up on deck from the engine room jacket water for example. However, as most vessels use steam, getting it on deck is not a problem if taken from the economiser.
Bawat uses standard components, which can be sourced from different suppliers as necessary making Bawat independent, he claimed. The company only designs the system and only the retention tank needs manufacturing. He also explained that Bawat can supply the equipment or get sub-contractors to do the entire manufacturing process and fitting.

Although having a relatively low capacity of between 30 - 700 cu m per hour, this doesn’t matter over a long tanker voyage, as the ballast water in a tank can be treated during the voyage.

He said that Bawat is going for USCG approval in the first quarter of next year and has already completed the land-based tests and is now embarking on shipboard testing using Lloyd’s Register.

The company was established in 2011 and received IMO DNV GL type approval in October 2014 and from BV in May 2015. In June 2015, Bawat received an ABS certificate of design assessment was awarded USCG AMS status in February, 2015.

As at the beginning of June, Bawat had received the same amount of inquiries when compared with the whole of last year. However Andreasen warned that in general there could be delivery bottlenecks ahead caused by other parties, such as class societies.



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