JPH01208524A - Steam injection type gas turbine engine - Google Patents

Abstract

PURPOSE: To produce an increase in power output of an engine by providing a high pressure boiler means for generating superheated steam with combustion exhaust gas downstream of a gas turbine engine and inducting the steam generated there to a combustor via a supplementary steam turbine. CONSTITUTION: Compressed air from a low pressure compressor 12 and a high pressure compressor 14 is supplied to a combustor 16 in which fuel is combusted to generate high pressure and high temperature gas which is supplied to a high pressure turbine 18 and a low pressure turbine means 20 for work. The steam via the low pressure turbine means 20 is inducted to a power turbine 26 to drive it and then drive an electricity generator 36 via an output shaft 28. In this case, a high pressure boiler 30 and a low pressure boiler 37 are arranged downstream of the power turbine 18. A supplementary steam turbine 32 combined with the electricity generator 36 is driven by the superheated steam generated in the high pressure boiler 30. The steam generated there is inducted to the combustor 16. The steam from the low pressure boiler 37 is inducted to the low pressure turbine means 20.

Description

DETAILED DESCRIPTION OF THE INVENTION This invention relates to gas turbine engines, and more particularly to steam-injected gas turbine engines having a small auxiliary high pressure steam turbine that extracts additional horsepower output from the engine and improves the thermal efficiency of the cycle. Regarding turbine engines.

BACKGROUND OF THE INVENTION The use of steam injection to improve the performance of gas turbine engines is well known. Typically, these engines generate steam from waste heat released by the engine and inject the steam into the cycle to improve the performance of the gas turbine. One such typical configuration is U.S. Patent Section 4,56
No. 9,195. In this US patent, steam is generated in an exhaust heat exchanger from engine exhaust heat alone or in combination with heat from one or more auxiliary combustors or burners located within the exhaust system.

The steam generated is injected into the engine. This injection is
It can be performed anywhere in various parts of the engine, including the main combustor, or in various turbines, including a low pressure turbine, a high pressure turbine, or a power turbine.

Various boilers can be located downstream from the power turbine to generate intermediate and low pressure steam that can then be injected into various parts of the engine.

Still, the large amount of steam flowing through the engine leaves the open cycle engine as non-condensable steam, which is a loss and reduces the thermal efficiency of the engine. Thus, although the use of steam injection has improved the operation of gas turbines, much of this steam leaves the engine and the efficiency and power output are not as high as possible.

SUMMARY OF THE INVENTION This invention utilizes a high-pressure boiler downstream of a power turbine to generate steam at very high pressure and temperature, thereby improving the power output and cycle thermal efficiency of a steam-injected gas turbine engine. Improve both. The steam then passes through a non-condensing high-pressure steam turbine (hereinafter referred to as the auxiliary steam turbine), which extracts horsepower from this superheated steam, resulting in much cooler steam.
It is still above saturation and still has enough pressure to inject into the combustor. This cold steam may be injected directly into the combustor or may be reheated to a much higher superheat temperature before being injected into the combustor. Cold steam can also be used to cool stationary vane sections instead of being reheated. By taking advantage of the boiler's ability to efficiently generate very high pressures, less non-condensable steam exits the open cycle when the total fuel flow rate to these engines is constant.

Table 1 shows that when the high pressure turbine rotor inlet temperature is constant and the fuel flow rate to the engine equipment is increased, the same amount of non-condensable steam leaves the open cycle.

This considerably improves the thermal efficiency of the cycle. At the same time, the horsepower output of the system is also improved by combining the output from the auxiliary steam turbine with the direct output of the power turbine via the auxiliary turbine gearbox. Use of an auxiliary steam turbine does not require changes in the control area of the engine, such as the diaphragm area of the nozzle of the high pressure turbine, low pressure turbine, or power turbine. However, the heat exchanger or boiler equipment must be designed to use an auxiliary steam turbine.

Accordingly, it is an object of the present invention to provide a gas turbine and a method of operating the engine that increases power output and improves thermal efficiency.

Another object of the invention is to provide a steam injection gas turbine engine that utilizes an auxiliary steam turbine to extract horsepower from steam generated in a high pressure boiler downstream of the power turbine.

Another object of the invention is to have a high pressure turbine downstream of the power turbine to generate superheated steam at a very high pressure which is then passed through an auxiliary steam turbine and then injected into the engine. The objective is to provide a gas turbine engine with a

Another object of the invention is to provide a steam injection gas turbine engine that reduces non-condensable steam lost from the engine to the exhaust for a given fuel flow rate to the engine system.

Briefly, one form of the invention provides a gas turbine engine having a compressor, combustor, and high pressure turbine in series combination. Engine power is extracted from the power turbine. There is a high pressure boiler downstream of the power turbine.
Generates superheated steam at very high pressure. An auxiliary steam turbine receives steam from the high pressure boiler and extracts power from the steam in addition to the power output extracted through the power turbine, thus increasing the power output and thermal efficiency of the engine. The steam is then returned to the engine by injection.

In one embodiment of the invention, the steam is reheated in a superheater before being injected back into the combustor. Another embodiment of the invention further includes an intermediate pressure boiler and/or low pressure boiler downstream of the power turbine to generate steam for injection into other parts of the engine, such as the turbine.

Steam from the auxiliary steam turbine can be used to cool the stationary vane section instead of being reheated in a superheater. Alternatively, it may be injected directly into the combustor to cool it.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention is directed to land or marine gas turbine engines that utilize a boiler system to recover heat in the exhaust gas. Typically, a gas turbine has a compressor, such as a low pressure and high pressure compressor, followed by a combustor, followed by a turbine, such as a low pressure and high pressure turbine. Takes power from the power turbine. Additionally, the invention includes a high pressure boiler downstream of the power turbine that is designed to produce superheated steam at very high pressures. This steam passes through an auxiliary steam turbine, which extracts horsepower from the steam. This vapor still remains at sufficient pressure and temperature above saturation so that it can be injected back into the combustor or other parts of the engine.

This configuration increases the power output of the engine as well as the thermal efficiency of its cycle. This increase is due to less non-condensable vapor being lost to the exhaust at a nominal fuel flow rate. Furthermore, the boiler has very low pumping losses,
It can generate very high pressure. Furthermore, pressure losses in the auxiliary steam turbine are not a problem since the boiler can easily develop pressure with only a small loss in steam temperature or mass flow. Another advantage is that, as a property of superheated steam, it is not a complete gas. At a given temperature within the operating temperature range, the enthalpy increases as the flow is throttled. Therefore, if we reduce the temperature, at the output of the auxiliary steam turbine, the pressure will drop considerably during its passage through the auxiliary steam turbine, when the incomplete gas will be at the same temperature, but at a higher pressure.
It has a -fold greater enthalpy than if it were a perfect gas.

A gas turbine engine is shown generally at 10 in FIG. This includes, in working fluid order, a low pressure compressor means (LPG) 12 followed by a high pressure compressor means (RP
C)14. including. As is well known, a combustor 16 receives fuel and produces a combustor power product that is sent to a high pressure turbine means (HPT) 18. This is followed by low pressure turbine means (LPT) 20. A two-shaft system is utilized, with the inner shaft 22 from the low pressure turbine driving the low pressure compressor and the outer shaft 24 from the high pressure turbine driving the high pressure compressor.

After this, the working fluid is transferred from the low pressure turbine to the power turbine 1.
The power turbine is used to drive an output device through its output shaft 28. Steam is typically injected into the combustor or other portion of the engine. Some steam is exhausted from the device and exits the open cycle as non-condensable steam. This is a loss in the equipment and therefore reduces the thermal efficiency of the cycle.

In this invention, the high pressure (HP) downstream of the power turbine is
) Add boiler 3G to the engine. Typically, this high pressure boiler is designed to produce superheated steam at very high pressure. As an example, the pressure may range from 1.500 to 3. It can be in the range of 500 psia and the superheated steam is at least 750''F.

An auxiliary steam turbine, indicated generally at 32, receives steam output from the high pressure boiler. Steam passes through an auxiliary steam turbine 32 and is then injected into the combustor via piping 34. Typically, the auxiliary turbine can operate at a pressure ratio of about 4:1.

Even then, the steam is above saturation and still has enough pressure to be injected into the combustor.

The advantage of this configuration is that the superheated steam is not a perfect gas, so that at operating temperatures its enthalpy increases as the flow is throttled. At the output of the auxiliary turbine, the temperature of the steam is lower than at its input. The pressure has also dropped considerably.

As a result, the incomplete gas, steam, now has a greater enthalpy than if it were a perfect gas at the same temperature but at a higher pressure.

The output from the auxiliary turbine 32 can be routed through a gearbox 35 or to a variable speed low frequency device or the like to obtain the desired speed. For example, the gear box is 3
,600 or 3.00ORPM (6011z or 5
011z), a 6:1 ratio can be used. As shown, a gearbox 35 serves to combine the output from the auxiliary turbine with the output of the main shaft 28 to operate the 6011z generator 36.

In addition to high pressure boiler 30, other boilers may be included, such as a lower pressure (LP) boiler 37 delivering steam to line 3B. The steam in the pipe 38 is a single turbine;
The figure shows that the fuel is injected into the low pressure turbine 20.

As shown in FIG. 1, steam output from the auxiliary steam turbine 32 is injected directly into the combustor. Since this steam is at a relatively low temperature, it helps cool the combustor.

In FIG. 2, the same reference symbols are used for similar parts, but the output from the high pressure boiler 3o is sent to the auxiliary steam turbine 32 as before. However, before the steam is injected into the combustor, it is first passed through a 4° superheater. This superheater is located between the power turbine 26 and the high pressure boiler 30. As a result, the steam is reheated to a much higher superheat temperature before being injected into the combustor. This superheater has further applications when an auxiliary purner is provided after the power turbine.

Such auxiliary burners increase the temperature of the power turbine output, which substantially increases the temperature of the high pressure boiler inlet. Such high temperatures require special materials in the boiler. The high-pressure superheater 40 removes this heat and lowers the temperature before the boiler.

Instead of using a superheater, the actual use of low temperature steam, such as that generated directly from an auxiliary steam turbine, to cool various parts of the engine, such as the stationary vane section, instead of reheating it. I can do it.

Also shown in FIG. 2 are an intermediate pressure (IP) boiler 42 and a low pressure boiler 44. The output from these boilers can be used to supply various turbines or other parts of the engine. As shown, medium pressure boiler 42
Steam is injected from line 46 into low pressure turbine 20 and from line 48 into power turbine 26 . Similarly, the power turbine receives an injection of steam from the low pressure boiler 44 via piping 50. FIG. 2 also shows the use of an intercooler as shown generally at 52.

Output from the auxiliary steam turbine 32 can be used to drive an auxiliary compressor. This is boiler 42.44
Pressurize the steam from the medium and low pressure boilers. This steam can then also be directly injected into the combustor.

In this way, the losses of the auxiliary compressor are compensated for by the combustor.

As shown in Table 1, when operating with an auxiliary steam turbine, the thermal efficiency is 2.8 when the auxiliary steam turbine is added.
A considerable increase of % is obtained.

Additionally, horsepower is improved by 14%. Note that this table does not take performance into account for boiler pump horsepower or power turbine rotor thrust bearing losses. Also, the operating line of the high pressure compressor is not increased.

The dimensions of the auxiliary steam turbine are very small. Approximately 7 inches long
A turbine with a diameter of 14 inches and 1 inch blades has a diameter of 0.8
With an efficiency of 75, it can produce approximately 6,600 horsepower. In the example of Table I, the steam flow rate of the turbine described above must be tripled. The output of the auxiliary steam turbine is
As shown in the figure, it can be geared to the main shaft of the generator. As shown in FIG. 1, a 6:1 reduction can be utilized up to 3.60 ORPM. The counter-rotating power turbine utilizes a two-stage reduction to 1,800 RPM.

FIG. 3 shows a T-S (temperature-entropy) diagram for the Rankine cycle as it passes through the engine previously shown in FIG. The steam injected into the main combustor follows line 60 and reaches point a. The steam then passes through various turbines with a decrease in temperature and pressure, as shown by line 62, until it reaches the point. If an auxiliary burner is installed after the power turbine, the temperature of the steam will rise to point C;
Steam output exits the exhaust flue at point f.

Without this invention, steam would first enter line 64;
Proceeding along line 66, it is injected into the main combustor. With a high pressure boiler present, the steam will follow curve 68 until it reaches point d at the inlet of the auxiliary steam turbine. after that,
The temperature and pressure decrease in the auxiliary steam turbine along line 69 until point e is reached. At this point, the temperature and pressure are still adequate to heat the main combustor.

It will be appreciated that the area between lines 66, 68, 69 represents the extra area under the curve. As is well known, this extra area under the curve improves the efficiency of the cycle as long as the exhaust flue temperature remains at the same level.

Therefore, using this invention, the overall thermal efficiency of the cycle is improved. Additionally, by using a high pressure boiler with an auxiliary steam turbine, horsepower can be recovered directly, resulting in less non-condensable steam exiting the exhaust for a given fuel flow rate.

Although the invention has been described with respect to particular examples and embodiments, those skilled in the art will appreciate that other embodiments and modifications can be made within the scope of the invention as defined by the claims. Good morning.

[Brief explanation of the drawing]

Fig. 1 is a schematic diagram of one embodiment of the present invention, Fig. 2 is a schematic diagram of another embodiment of the invention, and Fig. 3 is a T-3 (temperature-entropy) diagram of the Rankine cycle.
It shows the efficiency gains obtained by using an auxiliary steam turbine and high pressure boiler. Explanation of main symbols 12.14 Two compressors 16: Combustor 18: High pressure turbine 26: Power turbine 30: High pressure boiler 32: Auxiliary steam turbine

Claims (1)

[Claims] 1. A compressor, a combustor, a high-pressure turbine, and an output power turbine that generates output from the engine are combined in series, and further downstream from the power turbine, the engine is injected into the engine. high pressure boiler means for supplying superheated steam to increase the output of the engine, and receiving steam from the high pressure boiler means to extract additional power output from the engine before injecting the steam into the engine; A steam injection type gas turbine engine having an auxiliary steam turbine that increases power and thermal efficiency. 2. The steam injection type gas turbine engine according to claim 1, further comprising means for injecting superheated steam into the combustor. 3. A steam injection gas turbine engine according to claim 2, further comprising a superheater for reheating the steam before injecting it into the combustor, the superheater being downstream of the power turbine and upstream of the high pressure boiler means. 4. A steam injection gas turbine engine according to claim 3, which is located on the side. 5. The steam injection type gas turbine engine according to claim 1, further comprising means for utilizing said steam to cool a high temperature portion of the engine. 6. The steam injection gas turbine engine according to claim 5, wherein the high temperature section includes a stationary vane section. 7. An auxiliary turbine gear box coupled to the auxiliary steam turbine for obtaining a desired speed output.
The steam injection gas turbine engine described. 8. The steam injection gas turbine engine of claim 1, further comprising a variable speed constant frequency device coupled to said steam turbine for determining output at a desired speed. 9. The steam-injected gas turbine of claim 1, wherein the engine includes a counter-rotating power turbine, and further comprising two-stage transmission means coupled to said auxiliary steam turbine for obtaining a desired speed of output. institution. 10. A steam injection gas turbine engine according to claim 1, further comprising additional boiler means downstream of said high pressure boiler means operating at a lower pressure to generate steam for injection into a portion of the engine. 11. The steam of claim 10, wherein the engine includes a low pressure turbine, and the additional boiler means includes an intermediate pressure boiler for generating steam for injection into at least one of the high pressure turbine and the low pressure turbine. Injection type gas turbine engine. 12. A steam injection type gas turbine engine according to claim 1, further comprising low pressure boiler means for generating steam for injection into said power turbine. 13. An auxiliary compressor driven by the auxiliary steam turbine, the auxiliary compressor pressurizing steam from the additional low pressure boiler, and further means for injecting the steam from the auxiliary compressor into a combustor. The steam injection type gas turbine engine according to claim 10. 14. The high pressure boiler means is 1,500 to 3,50
A steam injection gas turbine engine according to claim 1, wherein the engine generates superheated steam having a pressure in the range of 0 psia. 15. The steam injection gas turbine engine of claim 1, wherein said high pressure boiler means generates superheated steam at a temperature at least 50 degrees above saturation. 16. In a method for improving the power output and thermal efficiency of a steam injection gas turbine engine having a series combination of a compressor, a combustor, a high pressure turbine, and a power turbine, in a high pressure boiler downstream of the power turbine. A method comprising the steps of generating superheated steam, extracting horsepower from the steam thus generated with an auxiliary steam turbine, and injecting the steam emerging from the auxiliary steam turbine into an engine. 17. The method of claim 16, wherein the steam is injected into a combustor. 18. The method of claim 16 including the step of reheating the steam prior to injection into the engine to reduce the amount of non-condensable steam exiting the open cycle. 19. The method of claim 16, wherein said steam is used to cool a stationary vane section of an engine. 20. The method of claim 16, wherein the output of the auxiliary steam turbine acts directly on the main output of the power turbine through an auxiliary turbine gearbox.