CN105423296B - A kind of burner outlet expansion segment and use its burner - Google Patents

Abstract

A burner outlet expansion section, by setting a concave cavity on the burner outlet expansion section, and arranging multiple groups of plasma actuators in the cavity, the plasma can heat the fluid, generate active particles, induce flow and strengthen the plasma in the cavity The vortex motion can promote fluid mixing in the combustion zone, improve the combustion state, enhance combustion stability, and shorten the flame length. And a burner using the burner outlet expansion section. The expansion section of the present invention achieves the effects of widening the stable operating range of the burner, improving combustion efficiency, and reducing the axial size of the combustion chamber, solves the problem of unstable combustion in the large-angle expansion section, and can also solve the problem of burning low calorific value fuels. Combustion instability problem.

Description

A burner outlet expansion section and a burner using the same

technical field

The invention relates to the field of combustion devices, in particular to a burner outlet expansion section and a burner using the same.

Background technique

Gas turbines are widely used in electric power, aviation, petrochemical and other industries due to their small size and large output power. Due to the energy crisis and environmental deterioration, it is urgent to develop high-efficiency and clean combustion chambers, which are required to have the characteristics of reliable ignition, stable combustion, high efficiency and low emissions. At present, the problem of environmental pollution in our country is very serious, and it is very urgent to develop clean combustion technology of gas turbines. Gas turbine manufacturers have developed a variety of clean combustion technologies, such as lean premixed combustion technology, dilute-phase premixed pre-evaporation technology, lean oil direct injection technology, and catalytic combustion technology. Although these technologies can effectively reduce pollutant emissions, they are all Facing the problem of unstable combustion. For example, a radial staged combustion technology for liquid fuel combustion developed by General Motors Corporation of the United States can effectively reduce nitrogen monoxide emissions. However, since the main flame is stable at the low-velocity edge of the shear layer, periodic vortex shedding will occur near the low-velocity region of the shear layer, and oscillations will easily occur near the stable point, and combustion instability will easily occur when operating in non-design conditions.

Similar to gas turbine burners, other types of industrial burners also face the contradiction between stable combustion and reduced pollutant emissions.

Contents of the invention

In view of the above technical problems, the purpose of the present invention is to provide a plasma concave cavity expansion section and a burner using the same.

In order to achieve the above purpose, as an aspect of the present invention, the present invention provides a plasma cavity expansion section, comprising:

The concave cavity is arranged in the middle of the expansion section of the outlet of the burner, and is used to generate a recirculation zone and stabilize combustion;

a high-voltage electrode and a ground electrode, located in the concave cavity, for generating plasma;

A high-voltage power supply or a high-voltage power supply terminal is used to provide high-voltage alternating current for the high-voltage electrode and the ground electrode.

Preferably, the expansion section of the burner outlet is a conical hollow structure, and is connected to the burner outlet through a flange. The outlet expansion section of the burner is made of ceramics or quartz glass, and the thickness is between 0.1 mm and 20 mm.

Preferably, the cross section of the concave cavity is arc-shaped, triangular, quadrangular or pentagonal, preferably semicircular.

Preferably, the high-voltage electrodes and the ground electrodes are arranged in pairs in a staggered form; the number of pairs of the high-voltage electrodes and the ground electrodes is between 1-100, preferably between 1-10.

Preferably, the materials of the high voltage electrode and the ground electrode are independently selected from copper, tungsten or molybdenum.

Preferably, the output voltage of the high-voltage power supply is 500V-50kV, the output frequency is 100-200kHz, and the output waveform is sine wave, square wave, sawtooth wave or pulse wave.

As another aspect of the present invention, the present invention also provides a combustor using the diverging section at the outlet of the combustor as described above. Wherein, the burner is a gas turbine burner, a boiler burner or a chemical furnace burner.

It can be seen from the above technical solutions that the expansion section of the plasma cavity of the present invention has the following beneficial effects:

(1) The device sets a cavity structure on the expansion section of the burner outlet, and the recirculation zone formed in the cavity can prevent the flame from being blown out and enhance combustion stability;

(2) By arranging multiple sets of dielectric barrier discharge plasma actuators in the concave cavity of the expansion section, the device can strengthen the vortex flow in the concave cavity through the plasma-induced flow, which can reduce the flow loss and prevent the flame from being blown. Extinguish, enhance the role of combustion stability;

(3) The ionization in the concave cavity can release heat and generate active groups, which strengthen the combustion reaction, prevent the flame from being blown out, and enhance combustion stability;

(4) The plasma actuator provided in the concave cavity can also play a role in ignition;

(5) The device can solve the combustion instability phenomenon in the large-angle expansion section, and the large-angle expansion section can reduce the length of the flame and reduce the axial size of the combustion chamber.

Description of drawings

Fig. 1 is the structural representation of the expansion section of the plasma cavity of the present invention;

Fig. 2 is a partial enlarged view on the right side of the expansion section of the plasma concave cavity shown in Fig. 1;

Fig. 3 is a partial enlarged view on the left side of the expansion section of the plasma concave cavity shown in Fig. 1;

Figure 4 is a schematic diagram of plasma-induced flow;

Figure 5 is a schematic diagram of the flow in the expansion section.

[Description of the main component symbols of the present invention]

10 - expansion section;

11-expansion section cavity; 12-flange mounting hole;

20 - high voltage power supply;

21-high voltage terminal; 22-ground terminal;

30 - high voltage electrode;

31 - the high voltage electrode of the first exciter; 32 - the high voltage electrode of the second exciter;

33-the high-voltage electrode of the third exciter; 34-the high-voltage electrode of the fourth group exciter;

35 - the high-voltage electrode of the fifth exciter;

40 - ground electrode;

41 - the ground electrode of the first exciter; 42 - the ground electrode of the second exciter;

43 - the ground electrode of the third exciter; 44 - the ground electrode of the fourth group exciter;

45 - the ground electrode of the fifth exciter;

50-electrode connection;

51-high-voltage electrode terminal; 52-high-voltage electrode confluence line;

53-ground electrode confluence line; 54-ground electrode terminal.

Detailed ways

In order to make the object, technical solution and advantages of the present invention clearer, the present invention will be described in further detail below in conjunction with specific embodiments and with reference to the accompanying drawings. It should be noted that in the drawings or descriptions of the specification, similar or identical parts use the same reference numerals. Implementations not shown or described in the accompanying drawings are forms known to those of ordinary skill in the art. Additionally, while illustrations of parameters including particular values may be provided herein, it should be understood that the parameters need not be exactly equal to the corresponding values, but rather may approximate the corresponding values within acceptable error margins or design constraints. The directional terms mentioned in the embodiments, such as "upper", "lower", "front", "rear", "left", "right", etc., are only referring to the directions of the drawings. Therefore, the directional terms used are for illustration rather than for limiting the protection scope of the present invention.

The invention discloses an expansion section of a plasma concave cavity. The expansion section is installed at the outlet of the burner, which can shrink the flame in a smaller range, enhance the transmission of active groups and energy between the flame clusters, and can enhance the stability of combustion. Resilience plays an important role and also significantly reduces flame noise. A smaller expansion angle in the expansion section is beneficial to the stability of the flame, but it will cause the remaining unburned reactants to burn further downstream of the flame, and the flame structure will become longer, which is not conducive to the control of mixing and emission, and at the same time reduces the uniformity of the outlet temperature. The expansion section adopts a larger expansion angle, which can make the recirculation zone shorter and thicker, which is beneficial to reduce the axial size of the combustion chamber, but when the expansion angle is too large, the flame will shake violently, which is not conducive to the stability of the flame. In the present invention, by setting a concave cavity on the expansion section and arranging multiple groups of plasma actuators in the concave cavity, the recirculation zone formed in the concave cavity can stably burn, and the intensity of the swirl flow in the concave cavity can be enhanced by plasma induced flow, and The active groups generated by ionization can promote the fluid mixing in the combustion zone, improve the combustion state, enhance the combustion stability, shorten the flame length, achieve the effect of broadening the stable operation range of the burner, improving the combustion efficiency, and reducing the axial size of the combustion chamber. Solving the problem of combustion instability in the large-angle expansion section can also solve the problem of combustion instability in the combustion of low calorific value fuels.

The expansion section of the plasma concave cavity of the present invention is a structure that can enhance combustion stability and prevent burners from extinguishing, and is especially suitable for various industrial burners such as gas turbine burners, boiler burners, and chemical furnace burners.

In an exemplary embodiment of the present invention, a plasma cavity expansion section is presented. Fig. 1 is the structural representation of the expansion section of the plasma concave cavity of the present invention; Fig. 2 is a partial enlarged view of the right side of the expansion section of the plasma concave cavity shown in Fig. 1; Fig. 3 is a schematic diagram of the expansion section of the plasma concave cavity shown in Fig. 1 Partial enlargement on the left. Please refer to FIG. 1 to FIG. 3 , the expansion section of the plasma cavity includes: an expansion section 10 , a high voltage power supply 20 , a high voltage electrode 30 , a ground electrode 40 and an electrode connecting wire 50 . Among them, the expansion section 10 is a conical hollow structure made of insulating materials such as ceramics and quartz glass, and its lower part is connected to the outlet of the burner through a flange to limit the flame range, enhance energy transmission, and stabilize combustion. The concave cavity 11 is arranged in the middle of the expansion section for creating a recirculation zone and stabilizing combustion. A high voltage electrode 30 and a ground electrode 40 are arranged in the cavity. The high-voltage electrode 30 and the ground electrode 40 are used to generate plasma, which can induce flow, heat fluid, generate active particles, and stabilize combustion. The high-voltage electrode 30 is connected to the high-voltage end 21 of the high-voltage power supply 20 through the high-voltage electrode junction line 52 and the high-voltage electrode binding post 51; connect. The high voltage power supply 20 is used to provide high voltage alternating current for the high voltage electrode 30 and the ground electrode 40 .

Preferably, the material of the expansion section 10 is ceramic or quartz glass, and the thickness is between 0.1-20 mm, more preferably between 1-10 mm, and still more preferably between 2-8 mm.

Preferably, the output voltage of the high voltage power supply 20 is 500V-50kV, the output frequency is 100-200kHz; the output waveform is sine wave, square wave, sawtooth wave or pulse wave.

Preferably, the high voltage electrode 30 and the ground electrode 40 are arranged in a staggered manner, and the electrode material can be copper, tungsten or molybdenum.

Preferably, the number of high voltage electrodes 30 and ground electrodes 40 is between 1-100, more preferably between 1-10, and still more preferably between 2-5.

Preferably, the cross section of the concave cavity 11 may be arc-shaped, triangular, quadrangular or more polygonal, and more preferably semicircular.

In this embodiment, five high-voltage electrodes 30 and five ground electrodes 40 are arranged in the cavity 11, and one adjacent high-voltage electrode 30 and one ground electrode 40 constitute a dielectric barrier discharge plasma actuator. Figure 4 is a schematic diagram of plasma-induced flow, please refer to Figure 4, after the high-voltage electrodes 30 and ground electrodes 40 arranged in a staggered manner are connected to high-voltage electricity, the nearby fluid is ionized to generate plasma, and the plasma can heat the fluid, generate active particles, and induce flow , Strengthen the vortex movement in the concave cavity, which can promote the fluid mixing in the combustion zone, improve the combustion state, enhance the combustion stability, and shorten the flame length. Plasma-induced flow in the cavity Please refer to Figure 5, the plasma-induced flow can strengthen the vortex flow in the cavity. In addition, the plasma can heat the gas and generate a variety of active particles. The active particles play an important role in the combustion reaction. The center is usually active particles such as atoms and groups, and the speed of the chain reaction depends on the concentration of active particles in the combustion zone. Therefore, if the discharge is used to generate plasma before combustion, it can play an ignition role; during the combustion reaction process, the combination of the concave cavity and the plasma can play a role in stabilizing combustion and preventing flameout.

So far, the present embodiment has been described in detail with reference to the drawings. Based on the above description, those skilled in the art should have a clear understanding of the expansion section of the plasma cavity of the present invention. In addition, the above definitions of each element and method are not limited to the various specific structures, shapes or methods mentioned in the embodiments, and those skilled in the art can easily modify or replace them.

To sum up, the expansion section of the plasma concave cavity of the present invention can be used in aviation, chemical industry, power generation, metallurgy and other industries, can solve the combustion instability problem of gas turbines, and can reduce the axial size of the combustion chamber and improve combustion efficiency.

The specific embodiments described above have further described the purpose, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above descriptions are only specific embodiments of the present invention, and are not intended to limit the present invention. Within the spirit and principles of the present invention, any modifications, equivalent replacements, improvements, etc., shall be included in the protection scope of the present invention.

Claims (12)

1. A burner outlet expansion section, characterized in that, comprising: The concave cavity is arranged in the middle of the expansion section of the outlet of the burner, and is used to generate a recirculation zone and stabilize combustion; a high-voltage electrode and a ground electrode, located in the concave cavity, for generating plasma; A high-voltage power supply or a high-voltage power supply terminal is used to provide high-voltage alternating current for the high-voltage electrode and the ground electrode. 2 . The burner outlet expansion section according to claim 1 , wherein the burner outlet expansion section has a conical hollow structure and is connected to the burner outlet through a flange. 3. The burner outlet expansion section according to claim 1, characterized in that the burner outlet expansion section is made of ceramics or quartz glass. 4. The burner outlet expansion section according to claim 1, characterized in that, the thickness of the burner outlet expansion section is between 0.1mm-20mm. 5 . The burner outlet expansion section according to claim 1 , characterized in that, the cross-section of the concave cavity is arc-shaped, triangular, quadrangular or pentagonal. 6. The burner outlet expansion section according to claim 1, wherein the high-voltage electrode is connected to the high-voltage end of the high-voltage power supply through a high-voltage electrode junction line and a high-voltage electrode terminal; The electrode junction line and the ground electrode terminal are connected to the ground terminal of the high voltage power supply. 7 . The burner outlet expansion section according to claim 1 , wherein the high voltage electrodes and the ground electrodes are arranged in pairs in a staggered manner. 8 . 8 . The burner outlet expansion section according to claim 7 , wherein the logarithm of the high-voltage electrode and the ground electrode is between 1-100. 9. The burner outlet expansion section according to claim 1, wherein the materials of the high voltage electrode and the ground electrode are independently selected from copper, tungsten or molybdenum. 10. The outlet expansion section of the burner according to claim 1, wherein the output voltage of the high-voltage power supply is 500V-50kV, the output frequency is 100-200kHz, and the output waveform is a sine wave, a square wave, a sawtooth wave or pulse wave. 11. A burner using the burner outlet expansion section according to any one of claims 1 to 10. 12. The burner according to claim 11, which is a gas turbine burner, a boiler burner or a chemical furnace burner.