Reheat heat exchanger power generation systems

A power generation system featuring enhanced efficiency through the inclusion of a reheat heat exchanger, comprising in combination:

• a high temperature high pressure source of working fluid;
• a reheat heat exchanger having a high pressure inlet downstream from said high temperature high pressure source of working fluid, a high pressure outlet, a low pressure inlet, a low pressure outlet, a high pressure path between said high pressure inlet and said high pressure outlet and a low pressure path between said low pressure inlet and said low pressure outlet, said high pressure path located in heat transfer relationship with said low pressure path;
• an expander having an inlet downstream from said high pressure outlet and a discharge, said expander adapted to expand the working fluid therein from a higher pressure to a lower pressure;
• said discharge of said expander upstream from said low pressure inlet of said reheat heat exchanger;
• and
• wherein said source of working fluid includes a combustor having an oxygen inlet, a hydrocarbon fuel inlet and a water inlet, said combustor adapted to combust the oxygen with the hydrocarbon fuel to produce the working fluid of substantially only steam and carbon dioxide, said combustor adapted to mix the water from said water inlet with the combustion products produced within said combustor.

A method for enhancing efficiency of a power generation system having a high temperature high pressure source of a working fluid, a first working fluid expander and a second working fluid expander downstream from the first working fluid expander, the method including the steps of:

• providing a reheat heat exchanger having a high pressure inlet, a high pressure outlet, a low pressure inlet, a low pressure outlet, a high pressure path between the high pressure inlet and the high pressure outlet, and a low pressure path between the low pressure inlet and the low pressure outlet, the high pressure path located in heat transfer relationship with the low pressure path;
• locating the reheat heat exchanger with the high pressure inlet downstream from the source of high temperature high pressure working fluid, the high pressure outlet upstream from the first working fluid expander, said low pressure inlet located downstream from a discharge of the first working fluid expander, and the low pressure outlet located upstream from the second working fluid expander;
• and
• separating the working fluid into separate constituents including at least water and carbon dioxide downstream from the second expander.

A reheat heat exchanger comprising in combination:

• a casing;
• a pair of tube sheets interfacing with said casing;
• a plurality of tubes extending between said tube sheets;
• a high pressure inlet located adjacent at least one of said tube sheets;
• a high pressure outlet located adjacent at least one of said tube sheets and opposite said high pressure inlet;
• a high pressure path extending between said high pressure inlet and said high pressure outlet, said high pressure path defined at least partially by interiors of said tubes;
• a low pressure inlet passing through said casing;
• a low pressure outlet passing through said casing;
• a low pressure path extending between said low pressure inlet and said low pressure outlet and in contact with an exterior surface of said tubes;
• wherein a first expander is located downstream from said high pressure outlet, said first expander including a discharge located upstream from said low pressure inlet;
• wherein a second expander is provided downstream from said low pressure outlet;
• and
• wherein a recirculation pathway is provided between a location downstream from said second expander and a location upstream from said high pressure inlet.