System and a method for heat treatment of water of a vessel

A system for heat treatment of water of a first vessel, the water comprising ballast water of the first vessel and/or waste water from hull cleaning of the first vessel, the system comprising:

• a system inlet;
• a system outlet;
• a heat application section;
• a heat recovering section comprising a primary inlet, a primary outlet, a secondary inlet, a secondary outlet, a first part, and a second part;
• and
• a heat treatment piping system coupling the system inlet to the system outlet via at least the first part of the heat recovering section, the heat application section, and the second part of the heat recovering section;
• the system being configured for a flow of the water from the system inlet to the system outlet,
• the system being non-fixed and not forming part of any fixed installation of the first vessel,
• the flow including the water flowing from the system inlet to and through the first part of the heat recovering section via the primary inlet,
• the flow including the water flowing from the first part of the heat recovering section via the primary outlet to and through the heat application section,
• the flow including the water flowing from the heat application section to and through the second part of the heat recovering section via the secondary inlet,
• the flow including the water flowing from the second part of the heat recovering section via the secondary outlet to the system outlet,
• the heat application section being configured to apply heat to the water such that the water is heated when flowing through the heat application section during use of the system,
• the system being configured to operate at a flow rate of at least 5 m3/h through the heat application section,
• the first part and the second part of the heat recovering section being configured to exchange at least part of the heat such that during the use of the system the water, which is flowing through the second part of the heat recovering section, is pre-heating the water, which is flowing through the first part of the heat recovering section,
• the system comprising a mode valve system,
• the mode valve system providing coupling between the system inlet and the primary inlet,
• the mode valve system providing coupling between the secondary outlet and the system outlet,
• the mode valve system providing coupling between the secondary outlet and the primary inlet,
• the system being configured to temporarily set the mode valve system such that the coupling between the secondary outlet and the primary inlet is open while the coupling between the system inlet and the primary inlet is closed and/or while the coupling between the secondary outlet and the system outlet is closed.