CN102933819A - Lean-fuel intake gas turbine - Google Patents

Abstract

Provided is a lean-fuel intake gas turbine which has no pressure loss in the exhaust gas line that may lead to a drop in engine output and can be reduced in size of the gas turbine. The lean-fuel intake gas turbine includes a compressor (1) for compressing a fuel-laden working gas (G1) below a combustible concentration limit into a compressed gas (G2), and a catalytic combustor (2) for burning the compressed gas (G2) by catalysis. The gas turbine further includes a turbine (3) which is driven with a combustion gas (G3) from the catalytic combustor (2), and a regenerator (6) for heating the compressed gas (G2) drawn from the compressor (1) into the catalytic combustor (2) using an exhaust gas (G4) supplied from the turbine (3) through an exhaust gas passageway (25). The gas turbine also includes a warming burner (7) for supplying into the exhaust gas passageway (25) a warming gas (G5) produced by burning a mixture of fuel and an extracted gas (G20) extracted from the compressor (1), and a bleed valve (8) for controlling the amount of the extracted gas (G20) supplied to the warming burner (7).

Description

lean fuel suction gas turbine

technical field

The present invention relates to a lean fuel gas turbine engine utilizing a low BTU gaseous fuel such as coal mine methane (CMM) extracted from coal mines or landfill gas generated in landfills.

Background technique

In the past, a lean fuel gas turbine engine has been known that draws in BTU gas with a methane concentration below its flammability limit, thereby combusting the methane component. According to the gas turbine engine, the working gas having a low concentration of methane is compressed by the compressor to generate compressed gas. The compressed gas is combusted via a catalytic reaction by the catalytic combustor to generate combustion gas. The combustion gases are then used to drive a turbine. The compressed gas discharged from the turbine is then transported to a regenerator or heat exchanger for preheating the compressed gas transported from the compressor to the catalytic combustor. In the exhaust passage connected between the outlet of the turbine and the inlet of the generator there is a duct burner in which a fuel such as natural gas is introduced and burned at start-up or low-load operation with exhaust gas having a low temperature . This increases the temperature of the exhaust gas, thereby sufficiently heating the compressed gas supplied from the compressor into the regenerator, thereby activating the catalytic burner and thereby driving the engine in an efficient manner. See JP 2010-19247(A).

Gas turbine engines are able to utilize VAM (Ventilation Air Methane) which is a low BTU gas with a low concentration of methane exhausted from coal mines. VAM has a methane concentration of only 1% or less. Therefore, VAM is usually emitted into the air without combustion. However, using VAM as a fuel for generating electricity by gas turbines, a certain amount of carbon dioxide emission credits can be obtained.

For the gas turbine engine mentioned above, because the duct burner is installed in the exhaust passage at the turbine outlet, since the exhaust gas from the turbine travels through the passage even in the rated operation with the duct burner closed, it will cause pressure loss and engine The output is reduced. Furthermore, the flow of combustion air to the duct burner cannot be controlled, making it difficult to relight the duct burner in the event of catalyst degradation in the catalytic burner. Also, since the duct burner is installed in the exhaust passage, the passage and ultimately the gas turbine should be relatively large in size.

The object of the present invention is to provide a lean fuel gas turbine engine with a gas turbine of small size without causing any reduction in engine output or any pressure loss in the exhaust system.

Contents of the invention

To this end, the lean fuel gas turbine engine includes: a compressor for compressing a working gas to produce a compressed gas having a concentration of flammable components less than its flammability limit; Combustion of compressed gas by catalytic reaction with the assistance to generate combustion gas; turbine adapted to be driven by combustion gas supplied from the catalytic combustor; The compressed gas supplied to the catalytic burner is heated; the burner is used to combust the gas extracted from the compressor with fuel to generate heated gas and supply the heated gas into the exhaust passage; and the valve is used to control the gas supplied to The amount of gas extracted from the burner.

According to this gas turbine engine, the compressor compresses the working gas whose concentration of combustible components is lower than its flammability limit to generate compressed gas. Compressed gas is combusted via a catalytic reaction in a catalytic combustor to generate high temperature combustion gas used to drive a turbine. When the inlet temperature of the catalytic burner is lower than the temperature required for starting the catalytic reaction, for example, during start-up or low-load operation, the heating burner generates heating gas by burning a mixture of fuel and gas extracted from the compressor, The heated gas is supplied into the exhaust passage to heat the exhaust gas. The heated exhaust gas is then heat exchanged with the compressed gas from the compressor at the generator. The heated compressed air increases the inlet temperature of the catalytic burner to activate catalytic combustion, which ensures a stable supply of high temperature combustion gas to the turbine. Also, the heating burner is disposed outside the exhaust passage, and thus does not cause pressure drop in the exhaust system and performance degradation of the engine. In addition, the use of lean gases such as CMM, VAM or landfill gas with lower fuel concentration or methane concentration to drive gas turbine engines or catalytic reactions does not generate NOx in rated operation where the burner is not activated and ensures reduction Emissions of methane gas, thereby helping to prevent global warming.

In addition, the heating burner is not provided in the exhaust passage, thus causing no pressure loss of the exhaust system or deterioration of the performance of the engine, and ensuring efficient operation of the engine. Also, no heating burners are provided in the exhaust passage, thus causing no enlargement of the passage or the gas turbine engine. Furthermore, the purge valve controls the amount of purge gas to the heating burner, thus ensuring proper control of purge gas during burner re-ignition to generate the amount of heating gas required by the burner. This facilitates ignition of the burner.

In a preferred embodiment, the extraction valve is adapted to continuously increase or decrease the amount of extraction gas supplied to the heating burner. According to this embodiment, the amount of extraction gas supplied to the heating burner is continuously controlled by the extraction valve. This ensures the amount of extracted gas and fuel supplied to the heating burner, and therefore, the flow rate and temperature of the heating gas from the burner can be controlled in a reliable manner. This enables the inlet temperature of the catalytic burner to be controlled in a stable manner.

In another preferred embodiment, during start-up operation of the gas turbine engine, the heating burner is started. According to this embodiment, the heating burner is operated in the starting operation of the engine to start the catalytic burner and then drive the engine smoothly, although in the normal starting operation, the temperature of the exhaust gas from the turbine is still low, so the catalytic burner does not Started to the extent required to supply high-pressure, high-temperature compressed gas into the turbine, thereby increasing the number of revolutions of the engine.

In another preferred embodiment, the heating burner is operated in off-rated operation of the gas turbine engine at a speed less than that of the rated operation. According to this embodiment, the total amount of working gas passing through the gas turbine engine in non-rated operation is smaller than in rated operation. This means that the heating burner requires a smaller amount of fuel, which allows smaller heating burners to be used in the engine.

In another preferred embodiment, the gas turbine engine is adapted to operate the heating burner in the event of a combustion failure of the catalytic burner. According to this embodiment, even when any combustion failure occurs due to degradation of the catalyst, the heating burner can be re-ignited to activate the catalytic burner, thereby preventing performance degradation of the engine.

In summary, a gas turbine engine can be started from lean gas with a lower fuel concentration, eg methane concentration. Moreover, the catalytic reaction does not generate NOx in rated operation, and also reduces the emission of methane gas. Also, since the heating burner is not disposed in the exhaust passage, a smaller exhaust passage can be used to reduce the size of the gas turbine engine. In addition, this structure does not cause pressure loss in the exhaust passage or performance degradation of the engine.

Description of drawings

1 is a schematic diagram showing the structure of a lean-gas gas turbine engine according to an embodiment of the present invention;

2 is a diagram showing a characteristic structure of a gas turbine engine according to an embodiment of the present invention; and

FIG. 3 is a time chart showing a start/stop operation of a gas turbine engine according to an embodiment of the present invention.

Detailed ways

Preferred embodiments according to the present invention will be described below with reference to the accompanying drawings. 1 is a schematic diagram showing the structure of a lean-fuel gas turbine engine according to an embodiment of the present invention, wherein the gas turbine generally denoted by GT has a compressor 1, a catalytic combustor 2 containing a catalyst such as platinum and palladium, and a The output of the gas turbine GT acts as a generator or starter for a rotating electric machine 4 .

Gas turbines use a mixture of air and fuel as working gas G1. The working gas can be a low BTU gas, such as VAM (Ventilation Air Methane) generated in coal mines, coal mine gas (CMM) with a concentration of combustible components (methane) extracted from coal mines greater than the concentration of VAM, or in garbage Landfill gas generated in the landfill. Working gas G1 is compressed by compressor 1 to generate high pressure compressed gas G2, which is transported to catalytic burner 2 where it is combusted by a catalytic reaction with the assistance of a catalyst such as platinum or palladium G2 to generate high temperature and high pressure combustion gas G3. The combustion gas G3 is supplied to the turbine 3 to drive the turbine. The turbine 3 is connected to the compressor 1 via a rotary shaft 5 in order to excite the compressor 1 via the turbine 3 . As described above, the gas turbine GT and the rotary electric machine 4 constitute the power generation device 50 .

Because the concentration of fuel or combustible components in the working gas G1 is less than its flammability limit, and the temperature of the fuel is lower than the minimum temperature required for flaming combustion, the working gas will not be compressed by the compressor 1 due to the increase in temperature ignite. The working gas G1 may be added with a high-concentration combustible gas to increase the fuel concentration.

The gas turbine GT also has a regenerator or heat exchanger 6 which heats the compressed gas G2 supplied from the compressor 1 to the catalytic burner 2 with the gas G4 discharged from the turbine 3, and a burner 7, And the burner 7 is used to generate the gas G5 which is used to heat the gas G4. Specifically, the combustor 7 adds fuel to the gas 20 extracted from the compressor 1 and burns the mixture to generate heated gas G5 mixed in the exhaust gas G4 supplied from the turbine 3 to the regenerator 6 . The burner 7 is connected to an extraction control valve 8 for controlling the amount of extraction gas G20 supplied to the burner 7 . Gas G4 from the regenerator is supplied to a muffler (not shown), noise reduced and then discharged to the atmosphere.

The flow of gas G20 to the burner 7 is controlled through the purge valve 8 in response to an output signal from the start controller 21 of the controller 20 which controls the overall operation of the system, as will be described in detail below .

The CMM flow rate from the CMM supply source 13 such as a coal mine to the burner 7 is controlled by the first fuel flow control valve 9, and the first fuel flow control valve 9 responds to the control signal from the start controller 21 of the controller 20. Work. Working gas G1 is prepared by mixing VAM from a VAM source 12 of a ventilation system of a coal mine or the like with CMM from a CMM source 13 as needed while controlling the amount of CMM by the second fuel flow control valve 10 . CMM contains about 10-30% methane, and VAM contains less than 1% methane. Flow control to the CMM is performed by the second fuel flow control valve 10 in response to a signal from a load/stop controller 22 in the controller 20 . A purge air source 19 is connected to the passage extending from the VAM source 12 to the compressor 1 for the purge operation performed during the start-up step.

A first temperature sensor 31 is set near the inlet of the catalytic burner 2 to detect the temperature of the gas entering the catalytic burner 2, and a second temperature sensor 32 is set near the catalytic burner 2 to detect the temperature of the gas discharged from the catalytic burner 2. temperature. The inlet temperature obtained by the first temperature sensor 31 is sent to the starting controller 21 as the first detected temperature signal, and the outlet temperature obtained by the second temperature sensor 32 is sent to the starting controller 21 and the starting controller 21 as the second detected temperature signal. Load/stop controller 22.

In addition, a third temperature sensor 33 is provided near the outlet of the turbine 3 to detect the temperature of the gas discharged from the turbine 3 . The outlet temperature obtained by the third temperature sensor 33 is transmitted to the load/stop controller 22 of the controller 20 as a third detected temperature. A fourth temperature sensor 34 is provided near the inlet of the regenerator 6 to detect the temperature of the gas entering the regenerator 6 . The inlet temperature obtained by the fourth temperature sensor 34 is transmitted to the start controller 21 of the controller 20 as a fourth detected temperature.

A rotary shaft 5 made of a single shaft member and connected between the compressor 1 and the turbine 3 is connected to the rotary electric machine 4 via a reducer 17 . The rotation shaft 5 supports a rotation sensor 36 to detect the number of revolutions of the rotation shaft 5 , which is then transmitted to the load/stop controller 22 of the controller 20 .

A load/stop controller 22 of the controller 20 transmits a signal indicative of electric power generated by the rotating electric machine 4 . The power conversion system 11 is arranged such that the load/stop controller 22 energizes the rotary electric machine 4 as a starter in a starting operation.

As shown in FIG. 2 , the turbine 3 and the regenerator 6 are connected to each other via an exhaust duct or channel 25 . Exhaust passage 25 includes a cylindrical portion 25 a close to the turbine and an expansion portion 25 b close to and expanding toward regenerator 6 , and burner 7 is connected to expansion portion 25 b to supply heated gas G5 to the inside of exhaust passage 25 . The expanded structure of the expanded portion 25b allows the heated gas G5 to be uniformly supplied into the inner space of the large regenerator 6 to complete heat exchange between the gases G2 and G5 while utilizing the entire inner space of the regenerator 6 .

CMM is supplied to the burner 7 from a CMM source ( FIG. 1 ), as described above. Also, an extraction gas passage 27 branched from the passage 24 for supplying the compressed gas G2 from the compressor 1 to the regenerator 6, on which the burner 7 and the valve 8 are mounted.

The basic operation including start control and loading control and stop control operation of the gas turbine GT will be described below with reference to FIG. 3 showing the start/stop time flow of the gas turbine. In the figure, characteristic curves A to E represent the number of revolutions of the rotary shaft of the gas turbine GT, the generated electric power, the opening ratio (open ratio) of the first fuel flow control valve 9, the opening of the second fuel flow control valve 10, respectively. rate and the opening rate of the exhaust valve 8.

Launch control operation is discussed first. In this operation, upon receiving a start instruction, the start controller 21 drives the power conversion system 11 in FIG. 1 to excite the rotary electric machine 4 . Furthermore, the valve 18 assumes an open position. This results in the gas turbine engine GT taking in air to be driven (purified) at a lower number of revolutions, eg 20~30% of the rated speed. The valve 18 then assumes the open position, causing the gas turbine GT to draw in VAM from the VAM source 12 to increase the number of revolutions up to, say, 60% of the rated speed in order to fire the combustor 7 in FIG. 1 to heat the regenerator 6, and heat the interior of the catalytic burner 2 up to the temperature required for the catalytic reaction. As shown in FIG. 3, the exhaust valve 8 is gradually opened after the purge operation is completed. After the burner 7 is ignited, the opening ratio of the valve 8 is kept constant. Then, during catalytic combustion in catalytic burner 2 in FIG. supply (supply CMM). Then, the combustion of the burner 7 is controlled to prevent the temperature increase at the inlet of the catalytic burner 2, which is also caused by the supply of CMM.

For example, as shown in FIG. 3, the combustion is controlled by gradually reducing the opening ratios E and C of the purge valve 8 and the first fuel flow control valve 9 and the combined amount of gas G20 and CMM supplied to the burner 7. . The inlet temperature of the catalytic burner 2 is detected by the temperature sensor 31 , and a signal indicating the detected temperature is transmitted to the start controller 12 of the controller 20 . After receiving the signal, the starting controller 21 transmits control signals to the purge valve 8 and the first fuel flow control valve 9 to control the opening ratios E and C thereof, respectively. As shown in Figure 3, when the generated electric power B exceeds 0kW, that is, when electric power generation starts, the opening ratios E and C of the air extraction valve 8 and the first fuel flow control valve 9 are reduced to 0, thereby stopping the flow to the burner. 7 Supply extraction gas G20 and CMM, thereby closing the burner flame.

Load control is discussed next. As shown in FIG. 3 , when power generation starts, in response to a control signal from the load/stop controller 22, the opening ratio D of the second fuel flow control valve 10 is increased, which increases the amount of fuel supplied from the CMM source 13 to the compressor 1. The amount of CMM. Furthermore, the catalytic burner 2 continues its catalytic combustion after the burner 7 has been completely switched off. Also, as shown in FIG. 3, the opening ratio D of the second fuel flow control valve 10 is gradually increased to increase the amount of CMM supplied to the compressor 1 until the number of revolutions A of the engine reaches the rated number (100%). , resulting in rated power B (rated load). When the load reaches the rated load, the concentration of CMM in the working gas G1 is controlled by controlling the amount of CMM supplied to the compressor 1 using the second fuel flow control valve 10 in FIG. 1 .

In the stop control, after receiving the stop signal, as shown in FIG. The amount of CMM for burner 2, which reduces the number of revolutions A of the engine and reduces the generated power to 0 (no load). This state is maintained for a certain period of time during which the engine as a whole is cooled (aftercooling). After the engine is sufficiently cooled, the second fuel flow control valve 10 is fully closed so as not to energize the gas turbine GT, which brings the gas turbine GT into a free-running state.

The burner 7 works not only when starting the engine, but also in case of any combustion failure in the catalytic burner 2 . For example, when the outlet temperature of the catalytic burner detected by the second temperature sensor 32 drops below a predetermined temperature, it is determined that a combustion failure has occurred due to deterioration of the catalyst, etc., and as a result, the controller 20 drives to open the air extraction valve 8 and the first fuel flow control valve 9, and ignite the burner 7. This increases the temperature of the exhaust gas G4 entering the regenerator 6 and the compressed gas G2 supplied to the catalytic burner 2, which energizes the catalytic burner 2 sufficiently to prevent a reduction in engine output.

According to the embodiment, the gas turbine engine can be driven smoothly. Specifically, in the starting operation of the engine, the temperature of the exhaust gas G4 from the turbine 3 is low, so it is unlikely to sufficiently activate the catalytic combustor 2, so it is difficult to supply high-pressure high-temperature compressed gas to the turbine and to increase rotation smoothly. However, according to these embodiments, the burner 7 is driven at the start operation of the engine, thereby increasing the temperature of the exhaust gas G4 entering the regenerator 6 . This ensures that the temperature of the compressed gas G2 to be supplied to the catalytic burner 2 is heated by heat exchange at the regenerator 6, which effectively activates the catalytic burner, thereby ensuring a smooth start of the engine.

Furthermore, since the heating burner 7 is disposed outside the exhaust passage 25 rather than inside the passage 25, no pressure loss or output drop in the exhaust passage occurs, which ensures efficient driving of the gas turbine GT. Also, since the heating burner is not disposed in the exhaust passage 25, the passage can be of smaller size, resulting in a compact gas turbine GT.

Also, an extraction valve 8 is provided on the upstream side of the heating burner 7 so as to continuously increase or decrease the amount of extraction gas G20 supplied to the burner 7 . This ensures that the amount of extracted gas G20 and fuel supplied to the burner 7 is properly controlled in response to the number of revolutions of the engine, which ensures control of the flow rate and temperature of the heating gas G5 from the burner 7 and thus of the catalytic burner 2. inlet temperature.

When the engine is operating at non-rated operation, the amount of working gas passing through the gas turbine is less than at rated operation. This results in less fuel being required to heat the burner 7, which means that the burner 7 can be of smaller size.

Although CMM and VAM are used as the working gas in the above-described embodiments, however, other gases having concentrations of combustible components smaller than their flammability limits may also be used.

Although the preferred embodiments of the present invention have been described with reference to the accompanying drawings, various changes can be made to these embodiments without departing from the gist of the present invention, and these changes are included in the protection scope of the present invention.

parts list

1: Compressor

2: Catalytic burner

3: Turbo

4: Generator

6: Regenerator

7: Heating burner

8: Exhaust valve

25: exhaust channel

G1: working gas

G2: compressed gas

G3: combustion gas

G4: Exhaust gas

G5: heating gas

G20: pump out gas

Claims (5)

1. A lean fuel gas turbine engine comprising: a compressor for compressing a working gas having a concentration of flammable constituents less than its flammability limit to produce a compressed gas; a catalytic burner for combusting said compressed gas by a catalytic reaction with the assistance of a catalyst contained therein to generate combustion gas; a turbine adapted to be driven by combustion gases supplied from said catalytic burner; a regenerator for heating the compressed gas supplied from the compressor to the catalytic combustor by exhaust gas supplied to the regenerator from the turbine via an exhaust passage; a burner for combusting gas drawn from the compressor with fuel to generate heated gas and supplying the heated gas into the exhaust passage; and A valve for controlling the amount of bleed gas supplied to the burner. 2. The lean fuel gas turbine engine of claim 1, wherein the valve is adapted to continuously increase or decrease the amount of extraction gas supplied to the heating combustor. 3. A lean fuel gas turbine engine as claimed in claim 1 or 2, wherein the heating burner is activated in a start operation of the gas turbine engine. 4. The lean fuel gas turbine engine according to claim 3, wherein the heating burner is operated in a condition where the gas turbine engine is operated at a non-rated operation in which the number of revolutions is less than that of the rated operation. 5. The lean fuel gas turbine engine according to any one of claims 1 to 3, wherein the heating burner operates when a combustion failure occurs in the catalytic burner.

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