AU2014220107A1

AU2014220107A1 - Device and method for controlling lean fuel intake gas turbine

Info

Publication number: AU2014220107A1
Application number: AU2014220107A
Authority: AU
Inventors: Yasushi DOURA; Soh KUROSAKA; Yoshihiro Yamasaki
Original assignee: Kawasaki Heavy Industries Ltd; Kawasaki Jukogyo KK
Current assignee: Kawasaki Motors Ltd
Priority date: 2013-02-22
Filing date: 2014-01-10
Publication date: 2015-10-15
Anticipated expiration: 2034-01-10
Also published as: JP2014163243A; CN105026733B; CN105026733A; AU2014220107B2; JP5592965B2; WO2014129226A1

Abstract

A method for controlling a lean fuel suction gas turbine engine (GT), which is equipped with a catalytic combustor (3) that burns a compressed gas compressed by a compressor (1) and supplies the burned gas to a turbine (5), and a heat exchanger (7) that heats the compressed gas with the exhaust gas from the turbine as a heating medium, and which uses as a fuel the combustible component contained in low-concentration methane gas. When the temperature of the suction gas flowing into the compressor (1) of the gas turbine engine (GT) is lower than a prescribed value, the rotational frequency of the engine is lowered in accordance with the temperature of the suction gas.

Description

DEVICE AND METHOD FOR CONTROLLING LEAN FUEL INTAKE GAS TURBINE CROSS REFERENCE TO THE RELATED APPLICATION 5 This application is based on and claims Convention priority to Japanese patent application No. 2013-032828, filed February 22, 2013, the entire disclosure of which is herein incorporated by reference as a part of this application. BACKGROUND OF THE INVENTION 10 (Field of the Invention) The present invention relates to a device and a method for controlling a lean fuel intake gas turbine engine which uses, as a fuel, a low-calorie gas such as CMM (Coal Mine Methane) and VAM (Ventilation Air Methane) generated in a coal mine. 15 (Description of Related Art) A lean fuel intake gas turbine engine has been proposed which, for example, mixes CMM generated in a coal mine with VAM or air, takes in the resultant mixture, and conibusts a combustible component contained in the mixture with a catalytic combustor (e.g., see Patent Document 1). In a gas 20 turbine which uses a catalytic combustor, if an intake temperature is low, there is a possibility that a catalyst becomes inactivated due to a decrease in an inlet temperature of the catalytic combustor and a blowout of the combustor occurs, so that operation cannot be maintained. As control to prevent such a decrease in the inlet temperature of the 25 catalytic combustor, a method has been proposed in which, in a gas turbine which mixes a fuel having a predetermined concentration with air and uses the resultant mixture, a flow rate of the air supplied and a flow rate of the fuel supplied are adjusted on the basis of pressure loss in a catalyst (e.g., see Patent Document 2).

[Related Art Document] [Patent Document] [Patent Document 1] JP Laid-open Patent Publication No. 2010-019247 [Patent Document 2] JP Laid-open Patent Publication No. H05-203151 5 SUMMARY OF THE INVENTION However, in control in which a parameter is corrected on the basis of pressure loss of a catalyst, it is difficult to perform appropriate control if the intake temperature decreases before or at start of the gas turbine engine. Also, in a lean fuel intake gas turbine engine which uses, as a fuel, CMM generated in 10 a coal mine, since the fuel concentration continuously varies, if control to directly increase the flow rate of the fuel is performed when the inlet temperature of the catalytic combustor decreases, supply of methane, which is a combustible component, becomes excessive, which may cause a burnout of the catalyst. Therefore, an object of the present invention is to provide a method 15 and a device for controlling a lean fuel intake gas turbine engine, which can prevent a blowout of a catalytic combustor to stably maintain an operating state of the gas turbine engine even if an intake temperature of the gas turbine engine is decreased. In order to achieve the above object, a control method or a control 20 device for controlling a gas turbine engine according to the present invention is a method or a device for controlling a lean fuel intake gas turbine engine that includes: a catalytic combustor configured to combust a compressed gas compressed by a compressor and supply the resultant gas to a turbine; and a heat exchanger configured to heat the compressed gas by utilizing, as a heating 25 medium, an exhaust gas from the turbine, the lean fuel intake gas turbine engine being configured to utilize, as a fuel, a combustible component contained in a low-concentration methane gas. In the method or device, when a temperature of an intake gas flowing into the compressor of the gas turbine engine is lower than a predetermined value, a rotation speed of the engine is decreased in -<2'accordance with the temperature of the intake gas. Specifically, the rotation speed is controlled by decreasing a rotation speed of a generator driven by the gas turbine engine, via a power converter provided between the generator and an external electric power system. 5 According to this configuration, the rotation speed of the lean fuel intake gas turbine engine is controlled in accordance with the intake temperature to maintain a catalyst inlet temperature. The rotation speed control in accordance with the intake temperature, that is, correction of the rotation speed command value, can be performed not only during rated operation of the gas 10 turbine engine but also at or before startup of the gas turbine engine. Thus, a blowout caused due to a decrease in the intake temperature of the catalytic combustor is assuredly prevented, and it is possible to stably maintain the operating state of the gas turbine engine. In the control method or control device for controlling the gas turbine 15 engine according to one embodiment of the present invention, the rotation speed is preferably controlled, specifically, by decreasing a rotation speed of a generator driven by the gas turbine engine, via a power converter provided between the generator and an external electric power system. In the lean fuel intake gas turbine engine in which the fuel concentration continuously varies, 20 when rotation speed control is performed through adjustment of the flow rate of the fuel, a burnout or blowout of the catalytic combustor is likely to occur. However, it is possible to achieve stable control by performing rotation speed control via the power converter. In the control method or control device for controlling the gas turbine 25 engine according to one embodiment of the present invention, an extraction passage to extract the compressed gas from a passage for the compressed gas to a passage for the exhaust gas and an extraction valve configured to adjust a flow rate of an extraction gas flowing through the extraction passage may further provided in the gas turbine engine, and an aperture of the extraction valve may be increased to increase an inlet temperature of the combustor. According to this configuration, even if the inlet temperature of the catalytic combustor cannot be maintained even by the above rotation speed control when the intake temperature is decreased, it is possible to assuredly maintain the inlet temperature of the 5 combustor to further stably operate the gas turbine engine. Any combination of at least two constructions, disclosed in the appended claims and/or the specification and/or the accompanying drawings should be construed as included within the scope of the present invention. In particular, any combination of two or more of the appended claims should be 10 equally construed as included within the scope of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS In any event, the present invention will become more clearly understood from the following description of embodiments thereof, when taken in conjunction with the accompanying drawings. However, the embodiments 15 and the drawings are given only for the purpose of illustration and explanation, and are not to be taken as limiting the scope of the present invention in any way whatsoever, which scope is to be determined by the appended claims. In the accompanying drawings, like reference numerals are used to denote like parts throughout the several views, and: 20 Fig. I is a block diagram showing a schematic configuration of a gas turbine engine which is a target to be controlled by a control method according to an embodiment of the present invention; and Fig. 2 is a block diagram showing a control logic of the control method according to the embodiment of the present invention. 25 DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments of the present invention will be described with reference to the drawings. Fig. I is a schematic configuration diagram showing a gas turbine engine GT which is a target to be controlled by a control method according to one embodiment of the present invention. The gas turbine ,<4>engine GT includes a compressor 1, a main combustor 3 of a single-can type, a turbine 5, and a heat exchanger 7. A generator 9 is driven by an output of the gas turbine engine GT. The gas turbine engine GT according to the present embodiment is 5 configured as a lean fuel intake gas turbine engine which mixes a low-calorie gas such as CMM (Coal Mine Methane) generated in a coal mine with air or VAM (Ventilation Air Methane) discharged from the coal mine, takes the resultant mixture into the gas turbine engine, and utilizes, as a fuel, a combustible component contained in the mixture. The main combustor 3 is configured as a 10 catalytic combustor including a catalyst such as platinum or palladium. As low-calorie gases used in the gas turbine engine GT, for example, two types of fuel gases having fuel concentrations different from each other, such as VAM generated in a VAM fuel source Sv such as a coal mine and CMM having a combustible component (methane) concentration higher than that of 15 VAM, are mixed by a mixer 11 to obtain an intake gas G 1, and the intake gas GI is introduced into the gas turbine engine GT through an intake inlet of the compressor 1. The mixer 11 is provided on a fuel introduction passage 12 through which CMM from a CMM fuel source Sc is introduced into the compressor 1. The flow rate of the CMM fuel is adjusted by a CMM fuel 20 control valve 13 provided upstream of the mixer 11 on the fuel introduction passage 12. An intake temperature meter T1 which measures the temperature of the intake gas G I is provided at the intake inlet of the compressor 1. The intake gas GI is compressed by the compressor 1 to obtain a high-pressure compressed gas G2, and the high-pressure compressed gas G2 is 25 sent to the main combustor 3. The compressed gas G2 is combusted through a catalytic reaction with the catalyst such as platinum or palladium in the main combustor 3 to generate a high-temperature and high-pressure combustion gas G3. The combustion gas G3 is supplied to the turbine 5 to drive the turbine 5.

An inlet temperature meter T2 and an outlet temperature meter T3 are provided at an inlet and an outlet of the main combustor 3, respectively. The turbine 5 is connected to the compressor 1 and the generator 9 via a rotary shaft 15, so that the compressor 1 and the generator 9 are driven by 5 the turbine 5. A rotation detector 18 which detects a rotation speed of the turbine 5 is provided on a portion of the rotary shaft 15 between the compressor I and the generator 9. The generator 9 is connected to an external electric power system 19 via a power converter 17. The power converter 17 includes a circuit which performs mutual conversion between direct-current power and 10 alternating-current power, and bi-directional power supply between the generator 9 and the electric power system 19 is performed through the power converter 17. The heat exchanger 7 heats the compressed gas G2, which is to be introduced from the compressor 1 to the main combustor 3, by utilizing, as a heating medium, a turbine exhaust gas G4 from the turbine 5. The compressed 15 gas G2 from the compressor I is sent through a compressed gas passage 21 to the heat exchanger 7, heated in the heat exchanger 7, and subsequently sent through a high-temperature compressed gas passage 25 to the main combustor 3. The turbine exhaust gas C4 having passed through the main combustor 3 and the turbine 5 flows through a turbine exhaust gas passage 29 into the heat exchanger 20 7. An exhaust gas G5 flowing out of the heat exchanger 7 is silenced through a silencer, which is not shown, and then discharged to the outside. The gas turbine engine GT also has an extraction passage 3 1 provided so as to be branched from the compressed gas passage 2 . The extraction passage 31 is connected to the exhaust gas passage 29, and a part of the 25 compressed gas G2 flowing through the compressed gas passage 21 is extracted to the exhaust gas passage 29 through the extraction passage 31 according to need. An extraction valve 33 which adjusts the flow rate of the compressed gas flowing through the extraction passage 31 is provided on the extraction passage 31.

Although not shown, an auxiliary combustor which warms up the heat exchanger 7 by supplying a high-temperature combustion gas to the heat exchanger 7 during a period from startup of the gas turbine engine GT to the time when the working temperature of the main combustor 3 reaches a predetermined 5 temperature may be provided downstream of the extraction valve 33 on the extraction passage 31. In this case, the auxiliary combustor is supplied with a fuel, for example, CMM, from a dedicated fuel supply passage. For the gas turbine engine GT having such a configuration, a controller 41 is provided. The controller 41 is configured to decrease the 10 rotation speed of the gas turbine engine GT in accordance with the temperature of the intake gas GI when the temperature of the intake gas G1 flowing into the compressor I is lower than a predetermined value. Hereinafter, a method of controlling the gas turbine engine GT by the controller 41 will be described in detail. In the control method according to the 15 present embodiment, as shown in Fig. 2, a rotation speed correction section 43 provided in the controller 41 corrects a rotation speed on the basis of a measurement result of the intake temperature meter Ti. Specifically, when the temperature of the intake gas G I measured by the intake temperature meter TI is equal to or higher than the predetermined value, the rotation speed correction 20 section 43 does not correct a rotation speed command value and maintains a rated rotation speed. If the temperature of the intake gas G1 measured by the intake temperature meter T1 is lower than the predetermined value, the rotation speed correction section 43 decreases the rotation speed command value in accordance with the temperature measurement value of the intake gas G 1. 25 Meanwhile, upon reception of the command value from the rotation speed correction section 43, a rotation speed control section 45 of the controller 41 controls the rotation speed of the generator 9 via the power converter 17 to control the rotation speed of the gas turbine engine GT. Specifically, a rotation speed command value of the rotation speed control section 45 is decreased to *--< 7 > decrease the rotation speed of the gas turbine engine GT, thereby preventing a decrease in the inlet temperature of the main combustor 3. When the rotation speed of the gas turbine engine GT is decreased, an intake amount of the intake gas G1 decreases and a fuel-air ratio within the main combustor 3 increases. In 5 this way, the outlet temperature of the main combustor 3 and the temperature of the turbine exhaust gas G4 are maintained, and the inlet temperature of the main combustor 3 heated via the heat exchanger 7 is also maintained. The controller 41 operates over an entire operation period including the time of startup and the time of rated operation of the gas turbine engine GT, 10 and performs the above rotation speed correction in accordance with the measured temperature of the intake gas G1. In addition, the controller 41 may be operated before startup (during stop) of the gas turbine engine GT, and rotation speed command value correction may be performed in accordance with the intake temperature. 15 Furthermore, when a decrease in the inlet temperature of the main combustor 3 measured by the inlet temperature meter T2 cannot be suppressed even by the above rotation speed control, a catalyst inlet temperature control section 47 of the controller 41 corrects an aperture command value for the extraction valve 33 to increase the aperture of the extraction valve 33, thereby 20 increasing the inlet temperature of the main combustor 3. By increasing the aperture of the extraction valve 33 to decrease the flow rate of the compressed gas G2 flowing into the main combustor 3, the fuel-air ratio within the main combustor 3 further increases. As a result, the outlet temperature of the main combustor 3 and the temperature of the turbine exhaust gas G4 are maintained, 25 and the inlet temperature of the main combustor 3 heated via the heat exchanger 7 is maintained. The aperture of the extraction valve 33 is controlled by the catalyst inlet temperature control section 47, whereby it is possible to assuredly maintain the inlet temperature of the main combustor 3 even if the inlet temperature of the -_<8>catalytic main combustor 3 cannot be maintained even by the above rotation speed control when the intake temperature is decreased. As described above, in the method for controlling the gas turbine engine according to the present embodiment, the rotation speed of the lean fuel 5 intake gas turbine engine GT is controlled in accordance with the intake temperature to maintain the catalyst inlet temperature. Thus, not only during rated operation but also at the time of startup, a blowout caused due to a decrease in the intake temperature of the catalytic main combustor 3 is assuredly prevented, and it is possible to stably maintain the operating state of the gas 10 turbine engine GT. Although the present invention has been described above in connection with the embodiments thereof with reference to the accompanying drawings, various additions, changes, or deletions can be made without departing from the gist of the present invention. Accordingly, such additions, changes, or 15 deletions are to be construed as included in the scope of the present invention. [Reference Numerals] I --- Compressor 3 -.-.Main combustor (Catalytic combustor) 5 --- Turbine 20 7 .-- Heat exchanger 9 .... Generator 17 --- Power converter 31 -... Extraction passage 33 .... Extraction valve 25 41 -' - Controller 43 --- Rotation speed correction section 45 --. Rotation speed control section 47 - - Catalyst inlet temperature control section GI - -- Intake gas -- <9>- GT - Gas turbine engine T - Intake temperature meter

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Claims

1. A control method of controlling a lean fuel intake gas turbine engine that includes: a catalytic combustor configured to combust a compressed gas compressed by a compressor and supply the resultant gas to a turbine; and a heat exchanger configured to heat the compressed gas by utilizing, as a heating medium, an exhaust gas from the turbine, the lean fuel intake gas turbine engine being configured to utilize, as a fuel, a combustible component contained in a low-concentration methane gas, the method comprising: decreasing a rotation speed of the engine, when a temperature of an intake gas flowing into the compressor of the gas turbine engine is lower than a predetermined value, in accordance with the temperature of the intake gas.

2. The control method for controlling the lean fuel intake gas turbine engine as claimed in claim 1, further comprising: providing a power converter between an external electric power and a generator driven by the gas turbine engine; and decreasing a rotation speed of the generator via the power converter to decrease the rotation speed of the engine.

3. The control method for controlling the lean fuel gas turbine engine as claimed in claim I or 2, further comprising: providing, in the gas turbine engine, an extraction passage to extract the compressed gas from a passage for the compressed gas to a passage for the exhaust gas and an extraction valve configured to adjust a flow rate of an extraction gas flowing through the extraction passage; and increasing an aperture of the extraction valve to increase an inlet temperature of the combustor.

4. A controller for controlling a lean fuel intake gas turbine engine including: a catalytic combustor configured to combust a compressed gas compressed by a compressor and supply the resultant gas to a turbine; and a heat exchanger configured to heat the compressed gas by utilizing, as a heating medium, an exhaust gas from the turbine, the lean fuel intake gas turbine engine being configured to utilize, as a fuel, a combustible component contained in a low-concentration methane gas, the device comprising: a rotation speed correction section configured to, when a temperature of an intake gas flowing into the compressor of the gas turbine engine is lower than a predetermined value, decrease a rotation speed command value for the engine in accordance with the temperature of the intake gas.

5. The controller for controlling the lean fuel gas turbine engine as claimed in claim 4, further comprising a rotation speed control section configured to control a rotation speed of a generator driven by the gas turbine engine, via a power converter provided between the generator and an external electric power, on the basis of the rotation speed command value from the rotation speed correction section.

6. The controller for controlling the lean fuel gas turbine engine as claimed in claim 4 or 5, wherein the gas turbine engine includes: an extraction passage through which the compressed gas from a passage for the compressed gas is extracted to a passage for the exhaust gas; and an extraction valve configured to adjust a flow rate of an extraction gas flowing through the extraction passage, and the control device further comprises a catalyst inlet temperature control section configured to increase an aperture of the extraction valve to decrease an inlet temperature of the combustor. -- <12>-