Cargo handling system for semi refrigerated gas carriers

Primary cargoes on semi-refrigerated gas carriers are LPGs, including C-propane with various ethane content, as well as propylene, ammonia, butane, DME, butadiene, VCM and certain chemicals.

Our cargo handling system provides shipowners and charterers a safe and flexible solution with the highest degree of efficiency. It is normally designed with two cooled cargo segregations, but tank combinations can be adjusted to support demands for flexibility. The manifold arrangement is designed for different terminal requirements, onshore and offshore, focusing on optimized loading and discharging. This reduces the time spent at terminal and thereby increases the vessels sailing time.

Depending on owner and charterer's demand, a deck tank can be part of the system design. The deck tank accommodates coolant for use during gassing up of the cargo tanks, but it can also be used for storage of condensate when gas freeing is needed. Alternatively, the same deck tank can be used for fuel storage – as part of Nord Gas Solutions' fuel supply system (LFSS).

The deck arrangement is designed for logical and easy access to all equipment, and most weather exposed instruments and major machinery are protected from the environment for improved durability and lifetime performance. The piping layout is designed primarily for gravity drainage of liquid back to cargo tanks, and the safety system includes state-of-the-art vents, gas detection and ESD's.

To effectively keep the cargo refrigerated during laden voyage, the system's reliquefaction plant ensures required pressure control. Connected to vapor domes on the cargo tanks, the reliquefaction system condenses the cargo vapor and returns it to the cargo tank bottom. Our system design ensures that class requirements for cargo cooling redundancy are met.

Our cargo handling system also comprises a discharging system and a control system. The discharging system features main cargo pumps, booster pumps, cargo heater, level gauging and a high-level alarm system. Our control system is offered in different versions, with the most advanced delivered as part of an IAS system supply. The controls can be delivered with interfaces to subsystems like an inert gas system, load computer or LFSS, and integration of the ballast system is applicable.