Exhaust gas heat recovery system in internal combustion engine

An exhaust gas heat recovery system in an internal combustion engine, comprising:

• an exhaust gas economizer having heat transfer sections including a preheating section, an evaporating section and a superheating section;
• a feed water heater for heating water fed to said heat transfer sections of the exhaust gas economizer;
• a steam separation drum for separating steam and saturated water from fluid of steam-water mixture discharged from the exhaust gas economizer;
• a mixed-pressure turbine having a high pressure side and a low pressure side, a piping for feeding part of the steam separated in said steam separation drum to said superheating section of the exhaust gas economizer and further transferring said steam to the high pressure side of said mixed-pressure turbine;
• a piping for feeding part of the saturated water separated in said steam separation drum to said feed water heater and said evaporating section of the exhaust gas economizer, respectively;
• a low pressure steam generator provided in said piping for returning the saturated water separated in said steam separation drum to said feed water heater;
• a piping for feeding low pressure steam in said low pressure steam generator to the low pressure side of said mixed-pressure turbine;
• and a piping for condensing exhausted steam from the mixed-pressure turbine in a condenser and thereafter circulating the water thus condensed to said feed water heater.