JP5316947B2 - Combustor for micro gas turbine - Google Patents

Description

  The present invention relates to a combustor for a micro gas turbine to be applied to a power generation device and a propulsion device.

  Development of an ultra-compact micro gas turbine for power generation that is lighter and quieter than a reciprocating engine as a driving power source for a robot and a portable power source in an emergency is underway, and an ultra-compact combustor is required as the combustor.

  Such a combustor for a micro gas turbine is small in size, and the stability of operation and the cleanliness of exhaust are important. For example, Patent Documents 1 and 2 have been proposed.

US Pat. No. 6,684,642, “GAS TURBINE ENGINE HAVING A MULTI-STAGE MULTI-PLANE COMBUSTION SYSTEM” International Publication No. 2008/047825, “Gas Turbine Combustor”

The above-described combustor for a micro gas turbine is small in size, and operation stability and exhaust cleanliness are important.
For example, assuming a small power generator with a capacity of several hundred W, extrapolating from a rule of thumb, the combustion chamber volume of the combustor for a micro gas turbine is about 100 cm ³ .
However, conventionally, in such a small combustion chamber, stable ignition performance, high combustion efficiency, low CO concentration and NOx could not be achieved.

  In particular, a micro gas turbine combustor using liquid fuel (for example, kerosene) as a fuel is desired because of its good portability. In such a liquid fired micro gas turbine combustor, the fuel flow rate is several mL / Since the flow rate is extremely small, it is difficult to sufficiently atomize the fuel, and it is difficult to perform good combustion. Occasionally, CO concentration and unburned content were high, and emission of odors and emissions was a problem.

  The present invention has been made in view of the above-described problems. That is, an object of the present invention is to provide a combustor for a micro gas turbine that can achieve stable ignition performance, high combustion efficiency, low CO concentration and NOx in a small combustion chamber.

According to the present invention, combustion for a micro gas turbine is provided that includes a cylindrical inner liner and outer liner that surround a central axis and a cylindrical inner liner, and a burner portion that performs fuel injection and ignition, and forms a hollow cylindrical combustion chamber therein. A vessel,
The combustion chamber includes a primary combustion chamber that is provided in the burner portion and has a relatively small outer diameter, and a secondary combustion chamber that is located downstream of the primary combustion chamber and has a relatively large outer diameter.
The primary combustion chamber is composed of an upstream ignition chamber and a downstream rapid dilution chamber, and has an annular intermediate throttle for narrowing the outer diameter of the primary combustion chamber,
There is provided a combustor for a micro gas turbine, characterized in that a premixed swirling flow having a high fuel concentration is formed and ignited in the ignition chamber, and a swirling flame is rapidly diluted in the rapid dilution chamber.

According to a preferred embodiment of the present invention, further, ignition air is introduced from the outside into the ignition chamber and dilution air is introduced from the outside into the rapid dilution chamber to form a swirling air flow surrounding the central axis. A swirling airflow forming device;
A liquid fuel injection device for injecting fuel in a swirling direction of a swirling air flow in the ignition chamber to form a premixed swirling flow;
An ignition device that ignites the premixed swirl flow in the ignition chamber to form a tubular flame surface.

Further, the swirling air flow forming device is provided in a burner portion, and an annular member that forms the primary combustion chamber on the inner side,
There are ignition air holes and dilution air holes penetrating from the outer surface of the annular member toward the swirling direction of the swirling air flow in the ignition chamber and the rapid dilution chamber, respectively.

  The fuel injection device preferably includes a fuel injection nozzle that injects fuel into the swirling air flow in the ignition chamber through the combustion air hole.

According to the configuration of the present invention, it is confirmed by the examples described later that stable combustion is possible and high combustion efficiency is obtained even when the annular combustion chamber is a small combustion chamber of 100 cm ³ or less. It was.

In particular, the primary combustion chamber is composed of an ignition chamber and a rapid dilution chamber, and has an annular intermediate throttle that narrows the outer diameter of the primary combustion chamber, so that the ignition air in the ignition chamber is adjusted from the intermediate throttle. As a result, the fuel concentration in the ignition chamber can be set high, and the combustion stability can be enhanced, thereby suppressing the exhaust gas odor and unburned emissions during ignition and idling. Further, by adjusting the dilution air in the rapid dilution chamber on the secondary combustion chamber side with the intermediate throttle, the swirling flame can be rapidly diluted to reduce NOx.

1 is a first embodiment of a combustor for a micro gas turbine according to the present invention. It is a combustion test result of the combustor of FIG. It is a block diagram of the testing apparatus of the combustor by this invention. It is 2nd Embodiment figure of the combustor for micro gas turbines by this invention.

  Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings. In addition, the same code | symbol is attached | subjected to the common part in each figure, and the overlapping description is abbreviate | omitted.

FIG. 1 is a diagram showing a first embodiment of a combustor for a micro gas turbine according to the present invention, in which (A) is a longitudinal sectional view and (B) is an AA sectional view thereof.
In this figure, a combustor 10 for micro gas turbine of the present invention (hereinafter simply referred to as “combustor”) includes an inner liner 12, an outer liner 14, and a burner portion 16.
The inner liner 12 and the outer liner 14 are each cylindrical, and are formed concentrically with respect to the central axis ZZ.

The burner portion 16 has an annular disc that closes the upstream end portions (lower ends in this figure) of the inner liner 12 and the outer liner 14. The downstream end portions (upper end in this figure) of the inner liner 12 and the outer liner 14 are opened to exhaust the generated combustion exhaust gas 9 to the outside through the turbine 2 and the exhaust pipe 6.
The combustion chamber 18 of the combustor 10 is a substantially annular region surrounded by the inner liner 12 and the outer liner 14.

In FIG. 1A, the combustion chamber 18 of the combustor 10 includes a primary combustion chamber 18a and a secondary combustion chamber 18b.
The primary combustion chamber 18a is provided on the end liner 12 side of the combustion chamber 18, and has an outer diameter D1 that is relatively small. Further, the secondary combustion chamber 18b is located on the downstream side (upper side in the drawing) of the primary combustion chamber 18a, and has an outer diameter D2 that is relatively large.

  In FIG. 1A, the primary combustion chamber 18a includes an ignition chamber 19a and a rapid dilution chamber 19b, and has an annular intermediate throttle 20 that narrows the outer diameter D1 of the primary combustion chamber 18a. The intermediate aperture 20 has a central hole with an inner diameter D3.

In Example 1 to be described later, the combustion chamber volume is 50 cm ³ , and the ratio of the outer diameter D1 of the primary combustion chamber 18a to the outer diameter D2 of the secondary combustion chamber 18b is 1: 1.36, the primary combustion chamber. The ratio of the outer diameter D1 of 18a and the inner diameter D3 of the intermediate diaphragm 20 is 1: 0.9.
However, the present invention is not limited to this, and can be arbitrarily changed.

1A and 1B, the combustor 10 of the present invention further includes a swirling air flow forming device 22, a liquid fuel injection device 24, and an ignition device 26.
The swirling air flow forming device 22 introduces the ignition air 7a from the outside into the ignition chamber 19a and introduces the diluting air 7b from the outside into the rapid dilution chamber 19b to form a swirling air flow surrounding the central axis ZZ. To do.
The liquid fuel injection device 24 injects the liquid fuel 8 toward the swirling direction of the swirling air flow formed in the ignition chamber 19a to form a premixed swirling flow.
The ignition device 26 is, for example, a known spark plug, and ignites the formed premixed swirl flow to form the tubular flame surface 11.

  In this example, the swirling air flow forming device 22 includes an annular member 23, an ignition air hole 23a, and a dilution air hole 23b. The annular member 23 is provided at an end liner side end of the inner surface of the outer liner 14 and forms a primary combustion chamber 18a on the inner side. The ignition air hole 23a penetrates from the outer surface of the annular member 23 toward the swirling direction of the swirling air flow in the ignition chamber 19a. The dilution air hole 23b penetrates from the outer surface of the annular member 23 toward the swirling direction of the swirling air flow in the rapid dilution chamber 19b.

  In this example, the liquid fuel injection device 24 is a fuel injection nozzle that injects the gas fuel 8 (for example, propane) into the swirling air flow in the ignition chamber 19a through the ignition air hole 23a.

In this example, two ignition air holes 23a are provided at the same interval in the circumferential direction, four dilution air holes 23b are provided at the same interval in the circumferential direction, and the fuel injection nozzle 24 is provided for each ignition. A total of two air holes 23a are provided.
With this configuration, it is possible to form a swirling air flow surrounding the central axis ZZ by introducing the ignition air 7a from the outside into the ignition chamber 19a from each ignition air hole 23a.
Further, it is possible to inject the liquid fuel 8 from the liquid fuel injection device 24 toward the swirling direction of the swirling air flow formed in the ignition chamber 19a to form a premixed swirling flow.
Further, the tubular flame surface 11 can be formed by igniting the premixed swirl flow formed in the ignition chamber 19 a by the ignition device 26.

The ignition air hole 23a and the dilution air hole 23b may be at least one place in the circumferential direction. Further, the fuel injection nozzle 24 may be at least one place in the circumferential direction. Moreover, each dimension is not limited to this Example, It can change arbitrarily.
Further, the swirling air flow forming device 22 is not limited to this example, and a swirler may be provided at the combustor inlet to form an air flow swirling over the entire combustor circumferential direction.

FIG. 2 shows a combustion test result of the combustor of FIG. In this test, propane gas was used as the fuel and the ignition characteristics were tested.
In this figure, the horizontal axis is the air flow rate, the vertical axis is the fuel flow rate, ◆ in the figure is the ignition limit with the above-mentioned intermediate restriction, and ■ is the ignition limit when there is no intermediate restriction. I cannot ignite. Without an intermediate throttle, it becomes impossible to ignite under conditions with a large air flow rate, but with an intermediate throttle, ignition is possible even under conditions with a small fuel flow rate and a large air flow rate.

  From the test results of FIG. 2, the primary combustion chamber 18a is composed of an ignition chamber 19a and a rapid dilution chamber 19b, and has an annular intermediate throttle 20 for narrowing the outer diameter of the primary combustion chamber 18a. By adjusting the air 7a, the fuel concentration in the ignition chamber 19a can be set high, and the ignition performance can be enhanced, thereby suppressing the exhaust gas odor and unburned emissions during ignition and idling. It was also confirmed that the swirling flame can be rapidly diluted to reduce NOx by adjusting the dilution air in the rapid dilution chamber 19b on the secondary combustion chamber side from the intermediate throttle 20.

(Experimental equipment and method)
FIG. 3 is a diagram showing a second embodiment of a combustor for a micro gas turbine according to the present invention.
The difference from the gas-fired combustor in FIG. 1 is that the injection valve and spark plug are changed for liquid fuel, and the other basic structure is the same.

FIG. 4 shows the result of the combustion test of the combustor of FIG. In this test, kerosene was used as the fuel, and the blowout limit of combustion stability was tested.
In this figure, the horizontal axis indicates the air flow rate, the vertical axis indicates the fuel flow rate, ♦ in the figure indicates the case with the above-described intermediate restriction, and ■ indicates the case without the intermediate restriction.

  From the test results of FIG. 2, the primary combustion chamber 18a is composed of an ignition chamber 19a and a rapid dilution chamber 19b, and has an annular intermediate throttle 20 for narrowing the outer diameter of the primary combustion chamber 18a. By adjusting the air 7a, the fuel concentration in the ignition chamber 19a can be set high, and the combustion stability can be increased, thereby suppressing the exhaust gas odor and unburned emissions during ignition and idling.

  In addition, this invention is not limited to embodiment mentioned above, Of course, a various change can be added in the range which does not deviate from the summary of this invention.

2 turbine, 6 exhaust pipe,
7a Air for ignition, 7b Air for dilution,
8 liquid fuel, 9 flue gas,
10 Combustor for micro gas turbine (combustor),
11 tubular flame surface, 12 inner liner, 12a downstream end,
14 outer liner, 16 burner section,
18 combustion chamber, 18a primary combustion chamber, 18b secondary combustion chamber,
19a ignition chamber, 19b rapid dilution chamber, 20 intermediate throttle,
22 swirling air flow forming device, 23 annular type member,
23a, 23b combustion air holes,
24 Liquid fuel injection device (fuel injection nozzle),
26 Ignition system

Claims (3)

A combustor for a micro gas turbine that includes a cylindrical inner liner and outer liner that surround a central axis and a burner portion that performs fuel injection and ignition, and forms a hollow cylindrical combustion chamber therein.
The combustion chamber includes a primary combustion chamber that is provided on the end liner side and has a relatively small outer diameter, and a secondary combustion chamber that is located downstream of the primary combustion chamber and has a relatively large outer diameter.
The primary combustion chamber includes an ignition chamber on the end liner side and a rapid dilution chamber on the secondary combustion chamber side, and has an annular intermediate throttle that narrows the outer diameter of the primary combustion chamber between the ignition chamber and the primary combustion chamber.
A combustor for a micro gas turbine, characterized in that a premixed swirling flow having a high fuel concentration is formed in the ignition chamber and ignited, and a swirling flame is rapidly diluted in the rapid dilution chamber. Furthermore, a swirling air flow forming device that introduces ignition air into the ignition chamber from outside and introduces dilution air from the outside into the rapid dilution chamber to form a swirling air flow surrounding the central axis;
A fuel injection device for injecting fuel in a swirling direction of the swirling air flow in the ignition chamber to form a premixed swirling flow;
The combustor for a micro gas turbine according to claim 1, further comprising an ignition device configured to ignite a premixed swirl flow in the ignition chamber to form a tubular flame surface. The swirling air flow forming device is provided in a burner portion, and an annular member that forms the primary combustion chamber on the inside thereof,
3. An ignition air hole and a dilution air hole penetrating from the outer surface of the annular member toward the swirling direction of the swirling air flow in the ignition chamber and the rapid dilution chamber, respectively. 3. The combustor for a micro gas turbine as described.

Images