Waste heat recovery system for vessel

A waste heat recovery system for a vessel for supplying, to a steam utilization device, steam generated by a steam generator, using waste heat from a main machine as a heat source, wherein

• a plurality of expansion machines are connected in parallel to one another, and excess steam without being supplied to the steam utilization device is supplied individually to the expansion machines by the opening/closing of gate valves arranged in the respective expansion machines respectively, wherein
• the plurality of expansion machines are configured to have the same capacity, wherein
• a control device is comprised further, wherein the control device is programmed to control such that,
• when the flow volume of excess steam supplied to the expansion machines exceeds an upper limit value of an allowable supply amount that is determined from the combination of the expansion machines, the gate valve of the one expansion machine that is least frequently used among the plurality of expansion machines in which excess steam is not supplied is open, whereas
• when the flow volume of excess steam supplied to the expansion machines is equal to or lower than a lower limit value of the allowable supply amount, the gate valve of the one expansion machine that is most frequently used among the plurality of expansion machines in which excess steam is supplied is closed.

A waste heat recovery system for a vessel for supplying, to a steam utilization device, steam generated by a steam generator, using waste heat from a main machine as a heat source, wherein

• a plurality of expansion machines are connected in parallel to one another, and excess steam without being supplied to the steam utilization device is supplied individually to the expansion machines by the opening/closing of gate valves arranged in the respective expansion machines respectively, wherein
• the plurality of expansion machines are configured from a combination of the different capacity, wherein
• a control device is comprised further, wherein the control device is programmed to control such that,
• the gate valve is open/closed such that the flow volume of excess steam is included, at a combination in which the number of expansion machines is minimum, in a range between a lower limit value and an upper limit value of an allowable supply amount that is determined from the combination of the expansion machines.