System for staged chilling of inlet air for gas turbines

• US 20040011046A1
• Filed: 07/26/2002
• Published: 01/22/2004
• Est. Priority Date: 08/06/1999
• Status: Active Grant

• Current Assignee: TAS Energy Incorporated
• Original Assignee: Tas Limited
• Inventors: Pierson, Tom L.
• Granted Patent: US 6,769,258 B2
• Time in Patent Office: Days
• US Class Current: 60/772
• CPC Class Codes: F01K 23/10 with exhaust fluid of one cycle heating the fluid in another cycle F01K17/025 takes precedence
• CPC Class Codes: F02C 7/143 before or between the compressor stages
• CPC Class Codes: F24F 3/06 characterised by the arrangements for the supply of heat-exchange fluid for the subsequent treatment of primary air in the room units
• CPC Class Codes: F24F 5/0017 using cold storage bodies, e.g. ice
• CPC Class Codes: F25B 2339/047 Water-cooled condensers
• CPC Class Codes: F25B 2400/06 Several compression cycles arranged in parallel
• CPC Class Codes: F25B 27/02 using waste heat, e.g. from internal-combustion engines
• CPC Class Codes: Y02A 30/274 using waste energy, e.g. from internal combustion engine
• CPC Class Codes: Y02E 20/16 Combined cycle power plant [CCPP], or combined cycle gas turbine [CCGT]
• CPC Class Codes: Y02E 60/14 Thermal energy storage

Abstract

A method for cooling inlet air to a gas turbine is provided. For example, a method is described including passing inlet air through a cooling coil that includes an opening for receiving the inlet air and that is operably connected to a gas turbine power plant. The gas turbine power plant may include at least one gas turbine, and at least one gas turbine inlet which receives the inlet air. The method may further include passing circulating water through a water chiller at a first flow rate to reduce the temperature of the circulating water, the water chiller including a conduit through which the circulating water is capable of passing and passing the circulating water having the first flow rate through the cooling coil in an amount sufficient to lower the temperature of the inlet air. Additionally, the method may include reducing the flow rate of the circulating water passing through the water chiller, passing the circulating water through a water chiller at a second flow rate to reduce the temperature of the circulating water, the second flow rate being lower than the first flow rate, and passing the circulating water having the second flow rate through the cooling coil in an amount sufficient to lower the temperature of the inlet air.

Claims

1. A method of chilling inlet air for a gas turbine power plant, comprising:

(a) passing inlet air through a cooling coil that includes an opening for receiving the inlet air and that is operably connected to a gas turbine power plant that includes at least one gas turbine, and at least one gas turbine inlet which receives the inlet air;

(b) passing circulating water through a water chiller at a first flow rate to reduce the temperature of the circulating water, the water chiller including a conduit through which the circulating water is capable of passing;

(c) passing the circulating water having the first flow rate through the cooling coil in an amount sufficient to lower the temperature of the inlet air;

(d) reducing the flow rate of the circulating water passing through the water chiller;

(e) passing the circulating water through a water chiller at a second flow rate to reduce the temperature of the circulating water, the second flow rate being lower than the first flow rate; and

(f) passing the circulating water having the second flow rate through the cooling coil in an amount sufficient to lower the temperature of the inlet air.

7. The method of claim 1, further comprising passing the circulating water through a heater prior to passing the circulating water through the cooling coil, in which the circulating water temperature is increased to a temperature that is higher than the temperature of the circulating water leaving the cooling coil and higher than the temperature of the air entering the cooling coil to maintain the minimum desired leaving air temperature.

8. The method of claim 1, additionally comprising adding an additive to the circulating water in an amount sufficient to depress the freezing point of the circulating water.

9. The method of claim 1, additionally comprising adding an additive to the circulating water in an amount sufficient to depress the freezing point of the circulating water and minimizing any negative performance derating due to the additive effect on the heat transfer properties of water.

10. The method of claim 1, additionally comprising adding a salt additive to the circulating water in an amount sufficient to depress the freezing point of the circulating water.

11. The method of claim 1, additionally comprising adding a salt additive to the circulating water in an amount sufficient to depress the freezing point of the circulating water to a point that would specifically provide for protection of the system during low ambient temperature operation and to protect the system during shut-down periods.

12. The method of claim 1, additionally comprising adding sodium nitrate to the circulating water in an amount sufficient to depress the freezing point of the circulating water.

13. The method of claim 1, additionally comprising adding potassium formate to the circulating water in an amount sufficient to depress the freezing point of the circulating water.

14. The method of claim 1, additionally comprising determining a set point and reducing the flow rate of the circulating water passing through the water chiller when the temperature difference between the circulating water entering the cooling coil and the circulating water leaving the cooling coil reaches the set point.

15. The method of claim 1, additionally comprising determining a leaving chilled water temperature set point and increasing the setpoint at reduced off-design ambient temperatures to maintain the desired air temperature off the coil until the temperature difference between the circulating water entering the cooling coil and the circulating water leaving the cooling coil reaches a minimum set point and reducing the flow rate of the circulating water passing through the water chiller and reducing the leaving chilled water temperature setpoint to maintain the desired air temperature off the coil.

16. The method of claim 1, additionally comprising passing the circulating water through a pump prior to passing the circulating water through the water chiller.

17. The method of claim 1, additionally comprising passing the circulating water through a pump prior to passing the circulating water through the water chiller, reducing the circulating water flowrate, and decreasing the temperature of the circulating water to maintain the desired leaving air temperature.

18. The method of claim 1, additionally comprising passing the circulating water through one or more pumps and reducing the flow rate of the circulating water by shutting off at least one of the one or more pumps.

19. The method of claim 1, additionally comprising passing the circulating water through one or more pumps mounted in parallel and reducing the flow rate of the circulating water by shutting off at least one of the one or more pumps during partial load conditions.

20. The method of claim 1, additionally comprising passing the circulating water through one or more pumps and reducing the flow rate of the circulating water by lowering the speed (RPM) of the pump via a variable frequency drive on the one or more pump motors.

21. The method of claim 1, in which the gas turbine inlet air temperature leaving the cooling coil is about 40°

F. to about 60°

F.

22. The method of claim 1, additionally comprising providing a temperature sensor contacting the inlet air leaving the cooling coil to monitor the inlet air temperature.

23. The method of claim 1, additionally comprising providing a temperature sensor contacting the inlet air leaving the cooling coil to monitor the inlet air temperature and lowering the temperature of the inlet circulating water when the inlet air temperature increases above the setpoint.

24. The method of claim 1, additionally comprising providing a wet bulb temperature sensor to monitor the ambient air wet bulb temperature entering the cooling coil.

25. The method of claim 1, additionally comprising providing a control system and a temperature sensor contacting the inlet air leaving the cooling coil to monitor the inlet air temperature and lowering the circulating water flowrate when the temperature difference between the circulating water entering the cooling coil and the circulating water leaving the cooling coil decreases to from about 50% to about 90% of the difference between the ambient air wet bulb temperature entering the cooling coil and the temperature of the leaving air.

26. The method of claim 1, in which the chilled water temperature entering the cooling coil is about 34°

F. to about 45°

F.

27. The method of claim 1, in which the cooling coil includes a multipass cooling coil.

28. The method of claim 1, in which the cooling coil includes a four pass cooling coil.

29. The method of claim 1, in which the cooling coil includes a six pass cooling coil.

30. The method of claim 1, in which the water chiller includes an evaporator.

31. The method of claim 1, additionally comprising providing a thermal water storage tank which is operably connected to the water chiller.

32. The method of claim 1, additionally comprising providing a thermal water storage tank which is operably connected to the water chiller and during a charge cycle, removing a first portion of circulating water from the thermal water storage tank, passing the removed first portion of water through the water chiller to lower the temperature of the removed first portion of circulating water and to provide a chilled removed first portion of water, and then introducing the chilled removed first portion of water into the thermal water storage tank, wherein the chilled removed first portion of water is introduced to the tank in an amount sufficient to lower the average temperature of the circulating water in the thermal water storage tank.

33. The method of claim 1, additionally comprising providing a thermal water storage tank which is operably connected to the water chiller and during a discharge cycle, chilling the inlet air by removing a second portion of water from the thermal water storage tank and then passing the second portion of water to the inlet cooling coil to make heat transfer contact between the second portion of the circulating water and the inlet air, such that the temperature of the inlet air is lowered.

34. The method of claim 1, further comprising controlling the inlet air temperatures of multiple gas turbines by throttling the flow of circulating water to the cooling coil of the gas turbine which has the lowest turbine inlet air temperature.

35. The method of claim 1, further comprising controlling the inlet air temperatures of multiple gas turbines by throttling the flow of circulating water to the cooling coil of the gas turbine which has the lowest turbine inlet air temperature and resetting the supply circulating water setpoint higher once the last gas turbine circulating water is throttled to maintain the desired turbine inlet air temperature until at least one of the gas turbines meets the desired inlet air temperature without throttling more than about 25% of fully open.

2. A method of chilling inlet air to a gas turbine power plant, comprising:

(a) providing a gas turbine power plant that includes at least one gas turbine and at least one compressor, and having a gas turbine inlet which receives inlet air;

(b) providing a system of circulating liquid chilling water including a chilling system that includes a first mechanical chiller and a second mechanical chiller, the first and second mechanical chillers being arranged in series;

(c) passing at least a portion of the liquid chilling water through the first mechanical chiller and the second mechanical chiller, the liquid chilling water passing through the first mechanical chiller being lowered to a first temperature, and the liquid chilling water passing through the second mechanical chiller being lowered to a second temperature that is lower than the first temperature, thus providing a staged liquid chilling water temperature drop, wherein the staged liquid chilling water temperature drop is from about 20°

F. to about 34°

F.;

(d) providing an inlet air chiller, comprising a cooling coil through which liquid chilling water passes, for lowering the temperature of inlet air being fed to the compressor through heat transfer between the liquid chilling water passing through the cooling coil and the inlet air, wherein the inlet air chiller provides a liquid chilling water temperature rise of from about 20°

F. to about 34°

F.;

(e) chilling the inlet air by directing the liquid chilling water to the inlet air chiller and passing the liquid chilling water through the cooling coil of the inlet air chiller to make heat transfer contact between the liquid chilling water and the inlet air; and

(f) adding potassium formate to the circulating water in an amount sufficient to depress the freezing point of the circulating water.

3. A method of chilling inlet air to a gas turbine power plant, comprising:

(a) providing a gas turbine power plant that includes at least one gas turbine and at least one compressor, and having a gas turbine inlet which receives inlet air;

(b) providing a system of circulating liquid chilling water including a chilling system that includes a first mechanical chiller and a second mechanical chiller, the first and second mechanical chillers being arranged in series;

(c) passing at least a portion of the liquid chilling water through the first mechanical chiller and the second mechanical chiller, the liquid chilling water passing through the first mechanical chiller being lowered to a first temperature, and the liquid chilling water passing through the second mechanical chiller being lowered to a second temperature that is lower than the first temperature, thus providing a staged liquid chilling water temperature drop, wherein the staged liquid chilling water temperature drop is from about 20°

F. to about 34°

F.;

(d) providing an inlet air chiller, comprising a cooling coil through which liquid chilling water passes, for lowering the temperature of inlet air being fed to the compressor through heat transfer between the liquid chilling water passing through the cooling coil and the inlet air, wherein the inlet air chiller provides a liquid chilling water temperature rise of from about 20°

F. to about 34°

F.;

(e) chilling the inlet air by directing the liquid chilling water to the inlet air chiller and passing the liquid chilling water through the cooling coil of the inlet air chiller to make heat transfer contact between the liquid chilling water and the inlet air; and

(f) contacting the inlet air leaving the cooling coil with a control system, a temperature sensor, and a relative humidity sensor to monitor the leaving air temperature and relative humidity of the leaving air and varying the flow or the temperature of the circulating water to maintain a relative humidity of the coil to below about 95% to about 99% RH for optimal efficiency in a combined cycle system.

4. A method of chilling inlet air for a gas turbine power plant, comprising:

(a) passing inlet air through a cooling coil that includes an opening for receiving the inlet air and that is operably connected to a gas turbine power plant that includes at least one gas turbine, and at least one gas turbine inlet which receives the inlet air;

(b) passing circulating water through a water chiller at a first flow rate to reduce the temperature of the circulating water, the water chiller including a conduit through which the circulating water is capable of passing;

(c) passing the circulating water having the first flow rate through the cooling coil in an amount sufficient to lower the temperature of the inlet air to a desired air temperature setpoint;

(d) reducing the flow rate of the circulating water passing through the water chiller during lower ambient off-design periods to maintain the desired air temperature setpoint;

(e) passing the reduced flowrate circulating water through the water chiller at a second flow rate and reducing the temperature of the circulating water to maintain the desired air temperature setpoint, the second flow rate being lower than the first flow rate; and

(f) passing the circulating water having the second flow rate through the cooling coil in an amount sufficient to lower the temperature of the inlet air to the desired air temperature setpoint.

5. A method of chilling inlet air for a gas turbine power plant, comprising:

(a) passing inlet air through a cooling coil that includes an opening for receiving the inlet air and that is operably connected to a gas turbine power plant that includes at least one gas turbine, and at least one gas turbine inlet which receives the inlet air;

(b) passing circulating water through a water chiller to reduce the temperature of the circulating water, the water chiller;

having at least one inlet for receiving circulating water, at least one conduit through which the circulating water is capable of passing at least one outlet for dispensing circulating water and having two or more sequentially positioned compressors for lowering the temperature of the circulating water in stages;

(c) passing the circulating water through the cooling coil in an amount sufficient to lower the temperature of the inlet air;

(d) reducing the flow rate of the circulating water passing through the two or more sequentially positioned compressors such that the circulating water passing through the two or more sequentially positioned compressors has a reduced flow rate; and

;

(e) passing the circulating water having the reduced flow rate through the cooling oil in an amount sufficient to lower the temperature of the inlet air.

6. A method of chilling inlet air for a gas turbine power plant, comprising:

(a) passing inlet air through a cooling coil that includes an opening for receiving inlet air and that is operably connected to a gas turbine power plant that includes at least one gas turbine and at least one gas turbine inlet which receives the inlet air;

(b) passing circulating water through a water chiller to reduce the temperature of the circulating water, the water chiller having at least one inlet for receiving circulating water, at least one conduit through which the circulating water is capable of passing, at least one outlet for dispensing circulating water and having two or more sequentially positioned compressors for lowering the temperature of the circulating water in stages;

(c) passing the circulating water through the cooling coil in an amount sufficient to lower the temperature of the inlet air to a desired leaving air temperature;

(d) reducing the flow rate of the circulating water passing through the two or more sequentially positioned compressors during lower ambient off-design conditions to maintain a higher circulating water delta T thereby allowing warmer water to pass through the upstream compressor thus improving the efficiency at partial load; and

(e) passing the circulating water having the reduced flow rate through the cooling coil in an amount sufficient to lower the temperature of the inlet air to the desired leaving air temperature.

36. A method of chilling inlet air for a gas turbine power plant, comprising:

(a) passing inlet air through a cooling coil;

(b) passing circulating water through a water chiller to reduce the temperature of the circulating water and to provide chilled water;

(c) passing the chilled water through the cooling coil to lower the temperature of the inlet air and to provide chilled inlet air; and

(d) supplying water in a fog to the chilled inlet air downstream of the cooling coil in an amount sufficient to supersaturate the already saturated chilled inlet air.

37. The method of claim 36, further comprising removing a portion of water from the inlet air via the condensate off of the cooling coil and then reintroducing that water through a high pressure spray or fog to the chilled inlet air.

38. The method of claim 36, additionally comprising providing a compressor within the gas turbine power plant, in which supplying water (fog) to the chilled inlet air includes entraining water in the chilled inlet air in an amount sufficient to lower the temperature of at least one stage of the compressor.

39. The method of claim 37, further comprising passing the chilled inlet air through a compressor to vaporize the water in the chilled inlet air and cool interstages of the compressor.

40. The method of claim 38, in which the chilled inlet air is at a saturation level.

41. The method of claim 39, in which the chilled inlet air is at a supersaturation level after the water is supplied.

42. The method of claim 36, further comprising removing a portion of water from the inlet air via the condensate off of the cooling coil to be stored until thye chilling system is off and then reintroducing that water to be evaporated in the airstream by means of a high pressure spray or fog and thereby achieving evaporative cooling to near the wetbulb temperature.