Feedwater Storage and Recirculation System and Method

1 . A feed water storage and recirculation system for a steam turbine power plant having a post-combustion carbon capture plant which uses steam from the power plant as a heat source for regeneration of absorbent and returns condensate from the post-combustion carbon capture plant to the steam turbine power plant comprising:

a feed water storage tank;

a deaerator integral to or fluidly in series with the feed water storage tank;

a steam extraction conduit to convey water/steam to the feed water storage tank and deaerator after extraction from a turbine of a steam turbine power plant;

a feed water supply conduit to supply feed water from the feed water storage tank to a boiler of a steam turbine power plant;

a low pressure condensate conduit comprising at least a PCC condensate conduit to return condensate from an associated post-combustion carbon capture plant to a location upstream of the deaerator, together with the condensate returning through the low pressure feed water heaters from the condenser;

a flow restrictor provided in the steam extraction conduit between the turbine and the feed water storage tank and deaerator.

2 . A feed water storage and recirculation system in accordance with claim 1 wherein the deaerator is integral with the feed water storage tank.

3 . A system in accordance with claim 1 wherein the storage tank includes a suitable level control.

4 . A system in accordance with claim 1 wherein the flow restrictor is a valve.

5 . A system in accordance with claim 4 wherein the flow restrictor is selected from: a control valve, a globe valve with a suitably shaped and actuated plug, a butterfly valve with a suitably shaped and actuated disk, a non-return valve with a suitably shaped and actuated restriction.

6 . A system in accordance with claim 1 wherein additional sources of low pressure condensate are supplied to a return point upstream of the deaerator.

7 . A system in accordance with claim 6 wherein additional sources of low pressure condensate are supplied as a mixture with condensate from the carbon capture plant via a common low pressure condensate conduit

8 . A method of modification of a feed water storage and recirculation system for the regenerative feed heating cycle of a steam turbine power plant, comprising the steps of incorporating a flow restrictor into the steam extraction conduit and providing a conduit to return how pressure condensate at least comprising condensate from an associated PCC system together with the condensate returning through the low pressure feed water heaters from the condenser to a location upstream of the deaerator feed associated with a feed water storage tank of the said feed water storage and recirculation system to produce a feed water storage and recirculation system.

9 . The method of claim 8 performed as a method of after-market modification of existing plant in situ.

10 . A steam turbine power plant having a post-combustion carbon capture system which uses steam from the power plant for auxiliary purposes and for example as a latent heat source for regeneration of absorbent, the steam turbine power plant incorporating as part of its regenerative feed heating cycle a feed water storage and recirculation system in accordance claim 1 .

11 . A plant in accordance with claim 10 wherein the post-combustion carbon capture system comprises an absorber column where CO 2 is separated from the flue gas by means of absorption by passing the gas through a column where the gas flows in an opposite direction to an absorbent in liquid phase.

12 . A plant in accordance with claim 10 wherein the post-combustion carbon capture system further comprises a regeneration column where CO 2 is removed from absorbent by regenerative heating.

13 . A plant in accordance with claim 12 comprising a condenser reboiler is disposed to receive absorbent solution and reboil the solution to regenerate lean absorbent.