Flue gas heat recovery system

A method of utilizing the heat in the flue gas leaving the steam boiler of a steam turbine power generation plant comprising:

• passing the boiler feed water entering the steam boiler in thermal contact with the flue gas exiting the boiler;
• passing a stream of cooling water in direct contact with said flue gas to transfer heat from said flue gas to said stream of cooling water;
• pumping at least a portion of said stream of cooling water through a heat pump to transfer heat from said stream of cooling water to a working fluid;
• passing said working fluid through a supplementary power generator to convert the heat transferred from the stream of cooling water to the working fluid into power.

Apparatus for recovering the heat from the flue gas leaving a combustion furnace of a steam boiler comprising:

• an economizer connected with the combustion furnace for the passage of a first stream of boiler feed water in thermal contact with the flue gas leaving the combustion furnace;
• a first direct contact gas cooler connected with said economizer for passing a second stream of cooling water in direct contact with the flue gas leaving the economizer whereby heat is removed from said flue gas and added to said second stream;
• and
• a heat pump connected in heat exchange relationship with said second stream and said first stream whereby heat is pumped from said second stream to said first stream.

Apparatus for recovering the heat from the flue gas leaving the combustion furnace of the steam boiler of a steam turbine power generation plant comprising:

• an economizer connected with the combustion furnace for the passage of a first stream of boiler feed water in thermal contact with the flue gas leaving the combustion furnace;
• a first direct contact gas cooler connected with said economizer for passing a second stream of cooling water in direct contact with the flue gas leaving the economizer whereby heat is removed from said flue gas and added to said second stream;
• a heat pump connected in heat exchange relationship with said second stream;
• and
• an auxiliary power generator connected in heat exchange relationship with said heat pump whereby heat removed by said second stream from said flue gas is pumped from said second stream to power said auxiliary power generator.