A system for producing electricity, the system comprising - a chemical recovery boiler adapted to supply superheated steam to a steam turbine driving a generator, the chemical recovery boiler comprising o a first flue gas discharge channel adapted to discharge the flue gases of the chemical recovery boiler and o a first heat exchanger arrangement (26, 27, 28) arranged in the first flue gas discharge channel and adapted to recover thermal energy from the flue gases of the chemical recovery boiler; - a lime kiln adapted to oxidize calcium carbonate (CaCO 3) of lime mud to produce lime (CaO), the lime kiln comprising o a second flue gas discharge channel adapted to discharge the flue gases of the lime kiln and o a second heat exchanger arrangement arranged in the second flue gas channel and adapted to recover thermal energy from the flue gases of the lime kiln; and - a circulation for heat transfer medium, characterized in that - the circulation comprises o the first heat exchanger arrangement (26, 27, 28), o the second heat exchanger arrangement, and o a pipeline (64, 75, 85) adapted to convey at least some of the heat transfer medium between the first heat exchanger arrangement (26, 27, 28) and the second heat exchanger arrangement, and - the system is configured to provide feed water of the chemical recovery boiler with thermal energy originating from flue gases of the lime kiln via a line of the circulation for heat transfer medium. - a chemical recovery boiler adapted to supply superheated steam to a steam turbine driving a generator, the chemical recovery boiler comprising o a first flue gas discharge channel adapted to discharge the flue gases of the chemical recovery boiler and o a first heat exchanger arrangement (26, 27, 28) arranged in the first flue gas discharge channel and adapted to recover thermal energy from the flue gases of the chemical recovery boiler; o a first flue gas discharge channel adapted to discharge the flue gases of the chemical recovery boiler and o a first heat exchanger arrangement (26, 27, 28) arranged in the first flue gas discharge channel and adapted to recover thermal energy from the flue gases of the chemical recovery boiler; - a lime kiln adapted to oxidize calcium carbonate (CaCO 3) of lime mud to produce lime (CaO), the lime kiln comprising o a second flue gas discharge channel adapted to discharge the flue gases of the lime kiln and o a second heat exchanger arrangement arranged in the second flue gas channel and adapted to recover thermal energy from the flue gases of the lime kiln; and o a second flue gas discharge channel adapted to discharge the flue gases of the lime kiln and o a second heat exchanger arrangement arranged in the second flue gas channel and adapted to recover thermal energy from the flue gases of the lime kiln; and - a circulation for heat transfer medium, characterized in that - the circulation comprises o the first heat exchanger arrangement (26, 27, 28), o the second heat exchanger arrangement, and o a pipeline (64, 75, 85) adapted to convey at least some of the heat transfer medium between the first heat exchanger arrangement (26, 27, 28) and the second heat exchanger arrangement, and - the system is configured to provide feed water of the chemical recovery boiler with thermal energy originating from flue gases of the lime kiln via a line of the circulation for heat transfer medium. o the first heat exchanger arrangement (26, 27, 28), o the second heat exchanger arrangement, and o a pipeline (64, 75, 85) adapted to convey at least some of the heat transfer medium between the first heat exchanger arrangement (26, 27, 28) and the second heat exchanger arrangement, and - the system is configured to provide feed water of the chemical recovery boiler with thermal energy originating from flue gases of the lime kiln via a line of the circulation for heat transfer medium. - the system is configured to provide feed water of the chemical recovery boiler with thermal energy originating from flue gases of the lime kiln via a line of the circulation for heat transfer medium.