CN101230790A - Predictive model-based control system for heavy-duty gas turbines - Google Patents

Abstract

A control system used for a heavy gas turbine and based on a forecasting model is disclosed, which is used for controlling a gap (128) between a turbine blade (122) and a turbine shell (120) and comprises an impacting cooling header (140) installed on the turbine shell (120), a temperature sensing device for determining temperature of the turbine shell (120), a blower (130), a control system (700) logic for determining a setting temperature of the shell (120) and a controller (710) for controlling the blower (130), wherein the blower (130) exerts the air onto the impacting cooling header (140) in order to cool the shell (120) to approach the setting temperature and control the gap (128).

Description

Predictive model-based control system for heavy-duty gas turbines

Cross References to Related Applications

This application is a continuation-in-part of US Application Serial No. 11/548,791, filed October 12, 2006, now pending, entitled "Impingement Cooling of Turbine Cases for Heavy-Duty Gas Turbines." This application is incorporated herein by reference.

Background technique

Air impingement cooling is often used to manage the casing temperature of small gas turbines and to reduce and maintain clearances between the rotor blades and the accompanying casing interior surfaces. One problem with air impingement cooling systems on heavy duty gas turbines is the ability to obtain uniform heat transfer coefficients across large uneven non-standard casing surfaces. On small gas turbines, small impingement holes and short nozzles are usually used for the surface distance. These factors produce the desired high heat transfer coefficient on the enclosure. One detrimental effect of using small impingement cooling holes is the need to operate with a high differential pressure drop across the holes. This results in a requirement for an undesirably high cooling air supply pressure, which negatively impacts the net efficiency of the heavy duty gas turbine.

Impulse cooling has been applied in aircraft engines as a method of turbo clearance control. However, impingement systems used on aircraft engines cannot be used in heavy turbine applications. Systems applied in aircraft engines utilize air taken from a compressor as a cooling medium. It is not feasible to use the extracted air from the compressor on heavy duty gas turbines due to the cooler air temperature required by the design heat transfer coefficient. Compared to aircraft engines, heavy gas turbines have significantly larger, non-uniform casing surfaces requiring complex header designs. In addition, the case thickness and case thickness variation are much greater on heavy duty gas turbines.

The clearance between the rotor blades and the accompanying inner surface of the casing cannot be easily measured in a fixture by using test equipment. But the clearance required should be controlled by allowing higher or lower impingement cooling.

Accordingly, there is a need in the art for an impingement cooling control system that can provide clearance control on heavy duty gas turbines.

Contents of the invention

In one embodiment, the present invention provides a method for controlling a clearance between a turbine blade and a turbine casing, the method may include determining a temperature of the casing; determining a set temperature of the casing based on a transfer function, wherein, The set temperature is an expected temperature of the enclosure for controlling the gap; and the temperature of the enclosure is corrected by the controller based on the set temperature.

In another embodiment, the present invention provides a system for controlling the temperature of a turbine casing, the system may include a temperature sensing device for determining the temperature of the turbine casing; a blower; a setting for determining the casing control system logic for temperature; and a controller for controlling a blower that applies air to the enclosure to cool the enclosure near a set temperature.

In yet another embodiment, the present invention provides a system for controlling the clearance between a turbine blade and a turbine casing, which system may include an impingement cooling header attached to the turbine casing; temperature sensing device for enclosure temperature; blower fan; control system logic for determining enclosure set temperature; and controller for controlling blower fan that applies air to an impingement cooling header to cool the enclosure Approximate set temperature and control clearance.

Description of drawings

FIG. 1 is a cross-sectional view of a heavy-duty gas turbine according to an embodiment of the present invention.

FIG. 2 is a partial enlarged view of a turbine blade-shroud gap according to an embodiment of the present invention.

Fig. 3 is an impingement cooling system according to an embodiment of the present invention.

4 is a perspective view of an impingement cooling header in accordance with an embodiment of the present invention.

5 is a cross-sectional view of an impingement cooling header according to an embodiment of the present invention.

6 is a perspective view of an impingement cooling header installed on a turbine casing in accordance with an embodiment of the present invention.

Fig. 7 is a control system according to an embodiment of the present invention.

Component symbol comparison table:

Heavy Turbine 110

Compressor section 112

Burner section 114

Turbine section 116

Compressor casing 118

Turbine casing 120

Turbine Blade 122

blade tip 123

Shield 126

Clearance 128

Blower 130

Air flow control door 132

Interconnecting pipes 134

Distribution Manager 136

orifice 138

Impingement Cooling Header 140

Top Plate 142

Supply pipe 144

Bottom plate 146

Impact hole 148

Supporting pillar 150

Fixed support 152

Impingement Air Cooling System 200

Control system 700

Controller 710

Modified flow rate box 720

Box for measuring ambient air temperature 730

Box for measuring case temperature 740

Transfer function box 760

Detailed ways

The present invention will now be described more fully hereinafter with reference to the accompanying drawings, in which exemplary embodiments of the invention are shown. However, this invention may be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided so that this disclosure will be thorough and complete, and will Those skilled in the art convey the scope of the invention.

FIG. 1 shows an exemplary embodiment of a heavy duty turbine 110 . The heavy duty turbine engine includes a compressor section 112 , a combustor section 114 and a turbine section 116 . The turbine 110 also includes a compressor casing 118 and a turbine casing 120 . The turbine casing 118 and the compressor casing 120 enclose the main parts of the heavy-duty turbine. Turbine section 116 includes a shaft and sets of rotating and stationary turbine blades.

Referring to FIGS. 1 and 2 , the turbine casing 120 may include a shroud 126 attached to an inner surface of the casing 120 . A shroud 126 may be positioned adjacent the tips of the turbine rotating blades 122 to reduce air leakage through the blade tips. The distance between blade tip 123 and shroud 126 is referred to as gap 128 . Note that the gap 128 for each turbine stage is not uniform due to the different thermal expansion characteristics of the blades and casing.

A key contributor to the efficiency of a heavy duty gas turbine is the amount of air/exhaust leakage through the blade tip-casing gap 128 . Due to the different thermal expansion characteristics of the turbine blades 123 and the turbine casing 120 , the gap 128 changes significantly as the turbine transitions through the transition from fired transient to base load steady state conditions. The clearance control system (including its sequence of operations) enables the handling of specific clearance characteristics under all operating conditions. Improper design and/or sequencing of the control system may result in excessive wear of the turbine blade 123 tips and casing shroud 126 , which may result in increased clearance and reduced performance.

As shown in the exemplary embodiment of FIG. 3 , an impingement air cooling system 200 may be used to reduce and maintain the clearance between the turbine shroud 126 and the accompanying blade tips 123 . Referring to FIG. 3, an impingement air cooling system 200 may include a blower 130, a flow control damper 132, interconnecting ducts 134, a distribution manifold 136, a throttle or orifice 138, and an impingement air inlet into a series (flow control damper) 132. Cooling header 140 . Impingement cooling headers are attached to the turbine casing. In the exemplary embodiment of FIG. 3 , a plurality of impingement headers 140 are attached about the perimeter of the turbine casing 120 . An impingement cooling blower 130 draws ambient air and blows the air through a damper door 132 , interconnecting ducts 134 , distribution manifold 136 , throttle or orifice 138 , and into impingement cooling header 140 . Blower 130 may be any blowing device including a fan or a nozzle. The impingement cooling header 140 ensures a uniform heat transfer coefficient is delivered to the turbine casing 120 . It should be understood that the impingement air cooling system is not limited to the components disclosed herein but may include any type of component that enables air to flow along the impingement cooling headers.

Referring to the exemplary embodiment shown in FIGS. 4 and 5 , the impingement cooling header 140 may be designed to contour the target area of the turbine casing 120 . Each impingement cooling header 140 may include a top plate 142 having a feed tube 144 , a bottom plate 146 having a plurality of impingement holes 148 , side pieces, support struts 150 , and fixed mounts 152 . Impingement holes 148 allow air to flow from the impingement cooling headers to the turbine casing to selectively cool the turbine casing.

The impingement holes 148 may be positioned in an array. In an exemplary embodiment, impingement holes 148 may be spaced in a range from 1.25 to 2.5 inches. In an exemplary embodiment, individual impingement holes 148 may be sized between 0.12 and 0.2 inches. Varying hole sizes and spacing are required to compensate for inhomogeneities in the turbine casing geometry. The size and location of the impingement holes 148 in the base plate 146 produces a uniform heat transfer coefficient through the enclosure that achieves the goals of the impingement air cooling system. However, the impingement holes are not limited to these sizes or spacings. The distance between the top plate 142 and the bottom plate 146 may also be sized to reduce variations in internal pressure, which would result in a uniform cooling hole pressure ratio.

The standoff distance between the impingement cooling header base plate 146 and the turbine casing 120 affects the heat transfer coefficient. Too large a spacing can result in a non-optimal heat transfer coefficient. Too small a spacing can lead to both non-optimal and non-uniform heat transfer coefficients. In an exemplary embodiment, a spacing between 0.5 and 1.0 inches provides a suitable heat transfer coefficient. However, the spacing is not limited to this range but may be any distance that provides an appropriate heat transfer coefficient.

As shown in FIG. 6 , exemplary embodiments may include a plurality of impingement cooling headers 140 . The plurality of impingement cooling headers 140 may be attached to the casing 120 of the turbine directly above the targeted cooling area. The impingement cooling headers 140 may be positioned so as to have ample spacing between their edges and any protrusions away from the cabinet. This provides a free path for air to pass through the impingement holes 148 to exit from beneath the impingement cooling header 140 into the environment. In an exemplary embodiment, the spacing between two adjacent impingement cooling headers may be between 1 and 30 inches and depends on the cabinet protrusion and flange joint. The spacing is not limited to these dimensions and may be spaced any suitable distance. The impingement cooling header 140 may also provide impingement cooling to any of the axial flanges, including horizontal split joints.

clearance control

The control system 700 can realize the control of the gap. Clearance may be measured directly during operation using a variety of sensors inside the turbine's casing, including but not limited to microwave clearance sensors and capacitive clearance sensors. However, the mortality rate of these sensors is very high. To avoid placing the sensor inside the enclosure, the enclosure temperature can be used to control the clearance. Clearance can be roughly estimated when the enclosure temperature is given. Accordingly, the control system 700 may be based in part on the temperature of the enclosure. Figure 7 shows an embodiment of a control system.

Exemplary embodiments of the control system logic portion of the control system 700 are described below with reference to block diagrams of systems, methods, devices and computer program products according to embodiments of the present invention. It will be understood that each block of the block diagrams, and combinations of blocks in the block diagrams, can be respectively implemented by computer program instructions. These computer program instructions may be loaded on a general purpose computer, or other programmable data processing apparatus, to generate a machine, such that the instructions executed on the computer or other programmable data processing apparatus generate instructions for implementing the means for the function of each block in a block diagram or a combination of blocks in a block diagram.

These computer program instructions can also be stored in a computer-readable memory that can instruct a computer or other programmable data processing device to operate in a specific manner, so that the instructions stored in the readable memory can produce instructions including implementing the specified in the block or block combination. The product of the command device of the function. Computer program instructions can also be loaded on a computer or other programmable data processing device to cause a series of operational steps to be executed on the computer or other programmable device, so as to produce a computer-implemented process such that a program executed on the computer or other programmable device The instructions provide the steps for implementing the function specified in the block or combination of blocks.

The control system 700 can be realized by an application program running on a computer operating system. The control system 700 is also practically applicable to other computer system configurations, including hand-held devices, multiprocessor systems, microprocessor-based or programmable consumer electronics, microcomputers, mainframe computers, and the like.

Application programs as components of the control system 700 may include subroutines, programs, components, data structures, etc. that implement certain abstract data types, perform certain operations, operations, or tasks. In a distributed computing environment, application programs may reside (in whole or in part) in local memory or in other storage devices. Additionally or in the alternative, the application program may be located (in whole or in part) in a remote memory or storage device to allow the practice of the invention to be performed by a remote processing device linked through a communication network. Exemplary embodiments of the present invention are described more fully hereinafter with reference to the accompanying drawings, wherein like numerals refer to like elements throughout the several drawings. Indeed, the invention may be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; rather, such embodiments are provided so that this disclosure will satisfy applicable statutory requirements.

As shown in the exemplary embodiment of FIG. 7 , a control system 700 for adjusting the inter-turbine clearance 128 may be based on the temperature of the casing 120 . The control system 700 may employ the controller 710 to correct turbine operating conditions that change the temperature of the casing 120 by controlling the cooling level for the heavy duty turbine.

Operating conditions that may be modified to change the temperature of the enclosure 120 may include air flow rate and coolant temperature. To illustrate, in the exemplary embodiment of FIG. 7 , at block 720 the controller 710 modifies the flow rate of air to change the enclosure temperature.

As shown earlier in FIG. 3 , ambient air may be applied to the turbine casing to cool the casing 120 by utilizing a blower 130 or any other air moving device. In an exemplary embodiment, air may be forced into impingement cooling headers 140 attached to the enclosure to cool the enclosure 120 . Air may also be forced into a plurality of impingement cooling headers 140 positioned near the perimeter of the enclosure 120 .

The temperature of the ambient air applied to the enclosure 120 may be measured at block 730 . The temperature of the turbine casing 120 is measured at block 740 . The temperature of the ambient air and the temperature of the cabinet can be measured by any temperature measuring device known to those of ordinary skill in the art.

At block 760, a transfer function may be performed to determine a set temperature based on current operating conditions. The set temperature may be the temperature of the enclosure and is set according to the desired gap 128 . Gap measurement data may be a function of current operating conditions, which may include gas turbine load, time, ambient temperature, rotor temperature, casing temperature. A transfer function can be created from the operating conditions and a gap model that mimics the expansion of the casing due to the current operating conditions. In the exemplary embodiment, the set temperature may be a function of ambient temperature, rotor temperature, and gas turbine load conditions.

If the clearance model determines that clearance 128 is below a minimum allowable value, the system may shut down or stop operation of the turbine. Otherwise, the output of the transfer function at 760 is the setpoint temperature.

The set temperature and enclosure temperature may be input into the controller 710 . The controller 710 outputs a control signal to the blower 130 to modify the flow rate of ambient air blown onto the enclosure 118 at block 720 . In the exemplary embodiment, controller 710 is a proportional-integral-derivative ("PID") controller. Those of ordinary skill in the art will understand that proportional controllers, integral controllers, or derivative controllers, alone or in combination, may be used to control the operating conditions of the turbine.

For the exemplary embodiment including many impingement cooling headers 140 , control system 600 may control air flow into one or more impingement cooling headers 140 . It is also contemplated that the control system 600 may be implemented separately with respect to each impingement cooling header 140 in order to control the local clearance of the cabinet 120 . It is also contemplated that multiple blowers 130 may be used to apply air to multiple impingement cooling headers 140 .

Those of ordinary skill in the art will appreciate that the present invention is not limited to the control system configurations shown herein. Those of ordinary skill in the art will appreciate that many variations of the control system can be implemented to ultimately control the temperature of the enclosure. For example, the control system may be an open loop control system based on gas turbine load conditions or any other permissible mode.

Many modifications and other embodiments of the invention will come to mind to those skilled in the art to which this invention pertains having the benefit of the teachings presented in the foregoing description and accompanying drawings. Therefore, it is to be understood that the inventions are not to be limited to the particular embodiments disclosed and that modifications and other embodiments are intended to be included within the scope of the appended claims. Although terminology is employed herein, it is used in a generic and descriptive sense only and not for purposes of limitation.

Claims (10)

1. method that is used to control the gap (128) between turbine blade (122) and the turbine casing (120) comprises:

Determine the temperature of described casing (120);

Determine the setting temperature of described casing (120) based on transfer function (760), wherein, described setting temperature is the desired temperature of the described casing (120) that is used to control described gap (128); With

Utilize controller (710) to revise the temperature of described casing (120) based on described setting temperature.

2. method according to claim 1 is characterized in that, the temperature of described casing (120) is applied to described casing (120) by gas fan (130) with air and upward revises.

3. method according to claim 1 is characterized in that, described method also comprises:

Impact type cooling manifold (140) is set on the described casing (120); With

Gas fan (130) is applied to air on the described impact type cooling manifold (140), so that revise the temperature of described casing (120).

4. method according to claim 3 is characterized in that, the air quantity (720) that described controller (710) control blows from described gas fan (130) is so that revise the approaching described setting temperature of the temperature of described casing (120).

5. method according to claim 3 is characterized in that, the air quantity (720) that enters a plurality of impact type cooling manifolds (140) that described controller (710) control blows from described gas fan (130).

6. method according to claim 1 is characterized in that, described transfer function (760) is based on the input that is selected from load, time, ambient temperature and casing (120) temperature.

7. method according to claim 1 is characterized in that, described controller (710) is the PID controller.

8. system that is used to control turbine casing (120) temperature comprises:

Be used for determining the temperature sensing device of described turbine casing (120) temperature;

Gas fan (130);

Be used for determining setting temperature controlling system (700) logic of described casing (120); With

Be used to control the controller (710) of described gas fan (130), wherein, described gas fan (130) is applied to air on the casing (118), so that cool off described casing (118) near described setting temperature.

9. system that is used to control the gap (128) between turbine blade (122) and the turbine casing (120) comprises:

Be installed in the impact type cooling manifold (140) on the turbine casing (120);

Be used for determining the temperature sensing device of described turbine casing (120) temperature;

Gas fan (130);

Be used for determining setting temperature controlling system (700) logic of described casing (120); With

Be used to control the controller (710) of described gas fan (130), wherein, described gas fan (130) is applied to air on the described impact type cooling manifold (140), so that cool off the approaching described setting temperature of described casing (120) and control described gap (128).

10. system according to claim 9 is characterized in that, described system also comprises a plurality of impact type cooling manifolds (140), so that reduce the cooling of described casing (120) and control described gap (128).

Images