High density combined cycle power plant process

A combined cycle power plant process comprising the steps of:

• operating at least one gas turbine (“GT”), wherein said GT produces exhaust gas;
• passing said exhaust gas through at least one heat recovery steam generator (“HRSG”) associated with said GT;
• supplemental firing said HRSG;
• producing steam at said HRSG using heat from said exhaust gas and said supplemental heat;
• passing said steam to at least one steam turbine (“ST”);
• operating said ST;
• converting said steam to feedwater;
• passing said feedwater to said HRSG;
• maintaining the temperature of said exhaust gas from said HRSG at a predetermined level by controlling the rate of supplemental firing of the HRSG when its associated GT load is between 0 and about 100% of its nominal power output capacity;
• and
• increasing plant capacity through additional supplemental firing and maintaining the temperature of the HRSG exhaust gas at said predetermined level by diverting feedwater from the HRSG when its associated GT load is at about 100% of its nominal power output capacity.

A combined cycle power plant process comprising:

• providing a topping cycle fluid (“TCF”) from a topping cycle engine (“TCE”) to a heat recovery device (“HRD”);
• recovering exhaust heat from the TCF in the HRD;
• substantially continuously supplemental firing the HRD;
• providing a bottoming cycle fluid (“BCF”) from the HRD to a bottoming cycle engine (“BCE”);
• and
• modulating the rate of BCF flow through at least a portion of the HRD such that an exhaust temperature of the HRD is maintained at a predetermined temperature range, thereby controlling heat recovery from the TCF in the HRD.

A combined cycle power plant process comprising:

• providing a topping cycle fluid (“TCF”) from a topping cycle engine (“TCE”) to a predominantly single pressure level heat recovery device (“HRD”);
• recovering exhaust heat from the TCF in the HRD;
• supplemental firing the HRD;
• providing a bottoming cycle fluid (“BCF”) from the HRD at a predominantly single pressure level to a bottoming cycle engine (“BCE”);
• and
• maintaining a TCF exhaust temperature of said HRD in a predetermined temperature range such that heat recovery in said HRD is controlled.

A method of operating a combined cycle power plant comprising at least one gas turbine (“GT”), at least one steam turbine (“ST”), and at least one heat recovery steam generator (“HRSG”), said method comprising:

• operating said GT to produce shaft work and exhaust gas;
• passing said exhaust gas through said HRSG;
• adding supplemental heat to said HRSG;
• producing steam at said HRSG using heat from said exhaust gas and said supplemental heat;
• passing said steam to said ST;
• operating said ST to produce shaft work;
• converting said steam to feedwater;
• passing said feedwater to said HRSG;
• and
• controlling flow of said feedwater through at least a portion of said HRSG to control heat recovery in said HRSG.

A method of operating a combined cycle power plant comprising at least one gas turbine (“GT”), at least one steam turbine (“ST”), and at least one single pressure level heat recovery steam generator (“HRSG”), said method comprising:

• operating said GT to produce shaft work and exhaust gas;
• passing said exhaust gas through said HRSG;
• adding supplemental heat to said HRSG;
• producing steam at said HRSG using heat from said exhaust gas and said supplemental heat, wherein said steam is produced at substantially a single pressure level;
• passing said steam to said ST;
• operating said ST to produce shaft work;
• converting said steam to feedwater;
• diverting at least some of said feedwater from said HRSG to a parallel feedwater loop;
• preheating said feedwater in said parallel feedwater loop;
• and
• supplying said diverted feedwater back to said HRSG

A method of operating a combined cycle power plant comprising at least one gas turbine (“GT”), at least one steam turbine (“ST”), and at least one heat recovery steam generator (“HRSG”), said method comprising:

• operating said GT to produce shaft work and exhaust gas;
• passing said exhaust gas through said HRSG;
• substantially continuously supplemental firing said HRSG(s), wherein total supplemental firing energy input is at least about 30% of the energy input to all of said GT(s);
• producing steam at said HRSG using heat from said exhaust gas and said supplemental heat;
• passing said steam to said ST;
• operating said ST to produce shaft work;
• converting said steam to feedwater;
• and
• passing said feedwater to said HRSG.

A method of operating a combined cycle power plant comprising at least one gas turbine (“GT”), at least one steam turbine (“ST”), and at least one heat recovery steam generator (“HRSG”) associated with at least one GT, said method comprising:

• operating said GT to produce shaft work and exhaust gas;
• passing said exhaust gas through said HRSG;
• supplemental firing said HRSG, wherein total supplemental firing energy input is at least about 30% of the energy input to its associated GT;
• producing steam at said HRSG using heat from said exhaust gas and said supplemental heat;
• passing said steam to said ST;
• operating said ST to produce shaft work;
• converting said steam to feedwater;
• passing said feedwater to said HRSG;
• and
• maintaining an exhaust temperature of said HRSG in a predetermined temperature range such that heat recovery in said HRSG is controlled.