Cold heat recovery system and marine vessel or floating body

A cold heat recovery system, comprising:

• a first fuel tank configured to store first fuel in a liquid state;
• a second fuel tank configured to store second fuel in a liquid state having a liquefaction temperature lower than a liquefaction temperature of the first fuel;
• a first fuel supply line for sending the first fuel extracted from the first fuel tank;
• a second fuel supply line for sending the second fuel extracted from the second fuel tank;
• a first cold heat recovery cycle configured to circulate a first heat medium and including a first expansion turbine for expanding the first heat medium in a gas state provided on the first cold heat recovery cycle;
• a first heat exchanger provided on a downstream side of the first expansion turbine on the first cold heat recovery cycle and configured to transfer cold energy from the first fuel flowing through the first fuel supply line to the first heat medium;
• a second heat exchanger provided on a downstream side of the first heat exchanger on the first fuel supply line and configured to transfer cold energy from the second fuel flowing through the second fuel supply line to the first fuel flowing through the first fuel supply line;
• a second cold heat recovery cycle configured to circulate a second heat medium and including a second expansion turbine for expanding the second heat medium in a gas state provided on the second cold heat recovery cycle;
• a third heat exchanger provided on a downstream side of the second expansion turbine on the second cold heat recovery cycle and configured to transfer cold energy to the second heat medium from the first fuel flowing on a downstream side of the second heat exchanger on the first fuel supply line;
• a fourth heat exchanger provided on a downstream side of the third heat exchanger on the first fuel supply line and configured to transfer cold energy from the second fuel flowing on a downstream side of the second heat exchanger on the second fuel supply line to the first fuel flowing through the first fuel supply line;
• a third cold heat recovery cycle configured to circulate a third heat medium and including a third expansion turbine for expanding the third heat medium in a gas state provided on the third cold heat recovery cycle;
• and
• a fifth heat exchanger provided on a downstream side of the third expansion turbine on the third cold heat recovery cycle and configured to transfer cold energy to the third heat medium from the first fuel flowing on a downstream side of the fourth heat exchanger on the first fuel supply line;
• a first bypass line for bypassing the second heat exchanger and guiding the second fuel to the fourth heat exchanger from an upstream side of the second heat exchanger on the second fuel supply line;
• and
• a flow control valve provided between a connection position at an upstream end of the first bypass line on the second fuel supply line and the second heat exchanger and configured to regulate a flow rate of the second fuel passing through the flow control valve.