High power density combined cycle power plant system

• US 6,606,848 B1
• Filed: 02/27/2001
• Issued: 08/19/2003
• Est. Priority Date: 08/31/1998
• Status: Expired due to Fees

• Current Assignee: William S. Rollins III
• Original Assignee: William S. Rollins III
• Inventors: Rollins, William S. III
• Primary Examiner(s): Casaregola, Louis J.
• Application Number:
  US09/763,920
• Time in Patent Office: 903 Days
• Field of Search: 60/391.82, 607/73, 122/7.R, 122/7.B
• US Class Current: 60/39.182
• CPC Class Codes: F01K 23/105 Regulating means specially adapted therefor
• CPC Class Codes: F01K 23/106 with water evaporated or preheated at different pressures in exhaust boiler
• CPC Class Codes: Y02E 20/14 Combined heat and power generation [CHP]
• CPC Class Codes: Y02E 20/16 Combined cycle power plant [CCPP], or combined cycle gas turbine [CCGT]
• CPC Class Codes: Y02P 80/15 On-site combined power, heat or cool generation or distribution, e.g. combined heat and power [CHP] supply

Abstract

A system and method for increasing the specific output of a combined cycle power plant and providing flexibility in the power plant rating, both without a commensurate increase in the plant heat rate, is disclosed. The present invention demonstrates that the process of upgrading thermal efficiencies of combined cycles can often be accomplished through the strategic use of additional fuel and/or heat input. In particular, gas turbines that exhaust into HRSGs can be supplemental fired to obtain much higher steam turbine outputs and greater overall plant ratings, but without a penalty on efficiency. This system and method by in large defines a high efficiency combined cycle power plant that is predominantly a Rankine (bottoming) cycle. Exemplary embodiments of the present invention include a load (1304) driven by a topping cycle engine (TCE) (1302), powered by a topping cycle fluid (TCF) (1301) that exhausts (1305) into a heat recovery device (HRD) (1306). Said HRD (1306) is fired with a supplementary fuel and/or provided an additional heat source (1314) to produce more energetic and/or a larger quantity of the bottoming cycle fluid (BCF) (1309) that is used to power a bottoming cycle engine (BCE) (1310) which drives a load (1311) (potentially the same load (1304) as the topping cycle engine (1302)). Energy contained in either the TCF (1301) or BCF (1308) is used to power the TCE (1302) and BCE (1310) respectively, but these fluids, and/or their respective engine exhausts, may also be used to support a wide variety of cogeneration applications.

Claims

1. A combined cycle power plant system comprising:

(a) at least one gas turbine (GT);

(b) at least one steam turbine (ST);

(c) at least one substantially continuously fired heat recovery steam generator (HRSG); and

(d) at least one control suitably adapted for maintaining a substantially optimum HRSG exhaust temperature, and having inputs comprising HRSG exhaust temperature, and having outputs comprising operational control of the rate of feedwater flow through an HRSG;

 

wherein

said power plant is operated predominantly as a Rankine Cycle power generation system utilizing said HRSG(s) along with said firing to supply high energy steam via a bottoming cycle to said ST(s), with a Brayton Cycle topping cycle being utilized to generate baseline power demand with said GT(s); and

said power plant utilizes a substantially single pressure bottoming cycle that generates high energy steam to drive said ST(s).

2. The combined cycle power plant system of claim 1 wherein ST extraction steam fed feedwater heating is utilized to augment cycle efficiency in said power plant.

3. The combined cycle power plant system of claim 1 wherein said firing and/or ST extraction steam is partially displaced by the recovery of energy from generator losses and/or other auxiliaries.

4. The combined cycle power plant system of claim 1 wherein said HP steam is predominantly at supercritical pressure at rated combined cycle plant output.

5. The combined cycle power plant system of claim 1 wherein the combined cycle efficiency $[\eta$

=(GTO+STO)(GTI+SFE)]

is approximately maintained at conventional combined cycle efficiency levels by designing the basic steam cycle for an efficiency $\left[\mathrm{SCE}=\frac{\mathrm{STO}}{\mathrm{HRS}\times <br><br>\mathrm{AXF}\times <br><br>\left(1-\mathrm{SGL}\right)}\right]$

that maintains the steam turbine generator electrical output [STO=HRS×

SCE×

AXF×

(1−

SGL)] as required.

6. The combined cycle power plant system of claim 1 wherein steam and/or GT exhaust energy is used to supply thermal cogeneration and/or CHP requirements.

7. A combined cycle power plant system comprising:

(a) at least one GT of sufficient capacity to supply 25% to 57% of the rated capacity of said power plant;

(b) at least one ST of sufficient capacity to supply said rated power plant capacity not supplied by said GT;

(c) at least one substantially continuously fired HRSG of sufficient capacity to recover GT(s) exhaust energy and supply sufficient high energy steam to said ST(s);

(d) means for interconnecting said GT(s), said ST(s), and said HRSG(s); and

(e) at least one control suitably adapted for maintaining a substantially optimum HRSG exhaust temperature, and having inputs comprising HRSG exhaust temperature, and having outputs comprising operational control of the rate of feedwater flow through an HRSG.

8. The combined cycle power plant system of claim 7 wherein ST extraction steam fed feedwater heating is utilized to augment cycle efficiency in said power plant.

9. The combined cycle power plant system of claim 7 wherein said firing and/or ST extraction steam is partially displaced by the recovery of energy from generator losses and/or other auxiliaries.

10. The combined cycle power plant system of claim 7 wherein said HP steam is predominantly at supercritical pressure at rated combined cycle plant output.

11. The combined cycle power plant system of claim 7 wherein the combined cycle efficiency $[\eta$

=(GTO+STO)(GTI+SFE)]

is approximately maintained at conventional combined cycle efficiency levels by designing the basic steam cycle for an efficiency $\left[\mathrm{SCE}=\frac{\mathrm{STO}}{\mathrm{HRS}\times <br><br>\mathrm{AXF}\times <br><br>\left(1-\mathrm{SGL}\right)}\right]$

that maintains the steam turbine generator electrical output [STO=HRS×

SCE×

AXF×

(1−

SGL)] as required.

12. The combined cycle power plant system of claim 7 wherein steam and/or GT exhaust energy is used to supply thermal cogeneration and/or CHP requirements.

13. A combined cycle power plant system comprising:

(a) at least one gas turbine (GT);

(b) at least one steam turbine (ST);

(c) at least one supplementary fired heat recovery steam generator (HRSG); and

(d) at least one control suitably adapted for maintaining a substantially optimum HRSG exhaust temperature, and having inputs comprising HRSG exhaust temperature, and having outputs comprising operational control of the rate of feedwater flow through an HRSG;

 

wherein

said supplemental firing of said HRSG(s) is modulated to increase at least one taken from the group consisting of the energy level and flow of steam supplied to said ST(s) to permit said ST(s) to operate at a substantially at least one taken from the group consisting of higher output and efficiency;

said supplemental firing of said HRSG(s) is designed to increase high temperature section energy level in said HRSG(s) to permit efficient GT(s) exhaust heat recovery while operating substantially at a singular pressure level;

said GT(s) and ST(s) are selected based on a capacity of said power plant and said GT(s) are designed to operate substantially at peak efficiency levels; and

said supplemental firing of said HRSG(s) is modulated primarily to compensate for the difference between the power demanded of a power plant and the power produced by said GT(s) and said ST(s), thus permitting an extension of the range of power generation permissible by said combined cycle power plant in comparison to combined cycle power plant systems in which said GT(s) are primarily modulated to supply said power demand.

14. The combined cycle power plant system of claim 13 wherein ST extraction steam fed feedwater heating is utilized to augment cycle efficiency in said power plant.

15. The combined cycle power plant system of claim 13 wherein said supplemental firing and/or ST extraction steam is partially displaced by the recovery of energy from generator losses and/or other auxiliaries.

16. The combined cycle power plant system of claim 13 wherein said HP steam is predominantly supercritical at rated combined cycle plant output.

17. The combined cycle power plant system of claim 13 wherein the combined cycle efficiency $[\eta$

=(GTO+STO)(GTI+SFE)]

is approximately maintained at conventional combined cycle efficiency levels by designing the basic steam cycle for an efficiency $\left[\mathrm{SCE}=\frac{\mathrm{STO}}{\mathrm{HRS}\times <br><br>\mathrm{AXF}\times <br><br>\left(1-\mathrm{SGL}\right)}\right]$

that maintains the steam turbine generator electrical output [STO=HRS×

SCE×

AXF×

(1−

SGL)] as required.

18. The combined cycle power plant system of claim 13 wherein steam and/or GT exhaust energy is used to supply thermal requirements such as space heating, chemical feedstock processing, pulp processing, paper drying, cogeneration, and/or other industrial processes.

19. A combined cycle power plant system comprising:

(a) at least one gas turbine (GT);

(b) at least one steam turbine (ST);

(c) at least one supplementary fired heat recovery steam generator (HRSG); and

(d) at least one control means for controlling HRSG exhaust temperature having inputs comprising HRSG exhaust temperature and having outputs comprising at least one taken from the group consisting of operational control of the rate of firing the HRSG and operational control of feedwater flow through the HRSG;

 

wherein

said supplementary firing of said HRSG(s) is substantially continuous; and

said supplemental firing of said HRSG(s) increases ST(s) inlet temperatures to the extent permissible by ST(s) inlet rating capability.

20. The combined cycle power plant system of claim 19 wherein ST extraction steam fed feedwater heating is utilized to augment cycle efficiency in said power plant.

21. The combined cycle power plant system of claim 19 wherein said supplemental firing and/or ST extraction steam is partially displaced by the recovery of energy from generator losses and/or other auxiliaries.

22. The combined cycle power plant system of claim 19 wherein said HP steam is predominantly at supercritical pressure at rated combined cycle plant output.

23. The combined cycle power plant system of claim 19 wherein the combined cycle efficiency $[\eta$

=(GTO+STO)(GTI+SFE)]

is approximately maintained at conventional combined cycle efficiency levels by designing the basic steam cycle for an efficiency $\left[\mathrm{SCE}=\frac{\mathrm{STO}}{\mathrm{HRS}\times <br><br>\mathrm{AXF}\times <br><br>\left(1-\mathrm{SGL}\right)}\right]$

that maintains the steam turbine generator electrical output [STO=HRS×

SCE×

AXF×

(1−

SGL)] as required.

24. The combined cycle power plant system of claim 19 wherein steam and/or GT exhaust energy is used to supply thermal cogeneration and/or CHP requirements.

25. A combined cycle power plant system comprising:

(a) at least one gas turbine (GT);

(b) at least one steam turbine (ST);

(c) at least one supplementary fired heat recovery steam generator (HRSG); and

(d) at least one control means for controlling HRSG exhaust temperature having inputs comprising HRSG exhaust temperature and having outputs comprising at least one taken from the group consisting of operational control of the rate of firing the HRSG and operational control of feedwater flow through the HRSG;

 

wherein

said supplementary firing of said HRSG(s) is substantially continuous; and

said supplemental firing of said HRSG(s) increases steam flow to said ST(s) to a level sufficient to economically justify the use of higher steam turbine inlet pressures and temperatures.

26. The combined cycle power plant system of claim 25 wherein ST extraction steam fed feedwater heating is utilized to augment cycle efficiency in said power plant.

27. The combined cycle power plant system of claim 25 wherein said supplemental firing and/or ST extraction steam is partially displaced by the recovery of energy from generator losses and/or other auxiliaries.

28. The combined cycle power plant system of claim 25 wherein said HP steam is predominantly at supercritical pressure at rated combined cycle plant output.

29. The combined cycle power plant system of claim 25 wherein the combined cycle efficiency $[\eta$

=(GTO+STO)(GTI+SFE)]

is approximately maintained at conventional combined cycle efficiency levels by designing the basic steam cycle for an efficiency $\left[\mathrm{SCE}=\frac{\mathrm{STO}}{\mathrm{HRS}\times <br><br>\mathrm{AXF}\times <br><br>\left(1-\mathrm{SGL}\right)}\right]$

that maintains the steam turbine generator electrical output [STO=HRS×

SCE×

AXF×

(1−

SGL)] as required.

30. The combined cycle power plant system of claim 25 wherein steam and/or GT exhaust energy is used to supply thermal cogeneration and/or CHP requirements.