CN107990353A - The jet nozzle of the soft combustion chamber of gas turbine - Google Patents

Abstract

A kind of jet nozzle of the soft combustion chamber of gas turbine, including：Spray orifice, multiple rotation launder channel, outside pipeline and inside pipelines on the outside of fuel inwardly projecting orifice, fuel.The mixture homogeneity of the jet nozzle outlet fuel and air has lifting, and outside fuel to air equivalence is than relatively low, be conducive to the lifting of flame root, it is not easy to catch fire too early, the jet stream of jet nozzle belongs to weak rotation, integral pressure loss is smaller, and axial velocity is not easy to decay, and is conducive to increase gas fume of combustion chamber reflux ratio.

Description

Jet Nozzles for Gentle Combustion Chambers of Gas Turbines

technical field

The invention relates to the technical field of gas turbines, in particular to a jet nozzle for a soft combustion chamber of a gas turbine.

Background technique

Nitrogen oxides include nitrous oxide, nitrogen monoxide, and nitrogen dioxide. Nitrogen oxides, as the main air pollutants, can cause poisonous damage to animals and plants, and are also one of the main causes of acid rain, acid fog and photochemical smog. Gas turbine is an important power equipment. On the one hand, it is necessary to continuously increase the outlet temperature of the combustion chamber to improve the efficiency of the gas turbine. On the other hand, it is necessary to further reduce the emission of nitrogen oxides in a wide range of operating conditions.

Under the premise of maintaining combustion efficiency and performance, reducing the emission of nitrogen oxides has always been the key goal of gas turbine combustion researchers. For gas turbines whose combustor outlet temperature is higher than 1500 °C, traditional diffusion combustion technology and premixed combustion technology face great challenges. Diffusion combustion technology has limited potential to reduce nitrogen oxide emissions; natural gas lean premixed combustion nozzles and control systems become more and more complex as the gas turbine level increases, and nitrogen oxide emissions do not meet the standards under low-load conditions. It is becoming more and more difficult to further reduce nitrogen oxides, and the lean premixing technology for burning coal to synthesis gas is not yet mature.

Compared with the traditional _NOx emission control technology, soft combustion technology has the advantages of stable flame, low noise, wide load range and high combustion efficiency. How to efficiently realize soft combustion conditions in the confined space of the gas turbine combustion chamber is the key and difficult point. The realization of the existing soft combustion is mainly to fully mix the fuel and flue gas before combustion, and use high-speed jets to form a recirculation zone in the combustion chamber. In general, in order to ensure uniform mixing of fuel and air, the nozzle adopts a strong swirl design. On the one hand, such a design often causes a large pressure loss, and the reaction zone is close to the outlet of the nozzle, which may easily cause local overheating of the nozzle. On the other hand, , The strong swirling jet flow of the nozzle will weaken the recirculation zone and reduce the flue gas recirculation ratio, which is not conducive to the establishment and realization of soft combustion. Therefore, there is still a lack of a jet nozzle in the field that can efficiently achieve soft combustion. On the basis of high-efficiency mixing, it is beneficial to reduce pressure loss and ensure the flue gas return ratio inside the combustion chamber, thereby achieving soft combustion and reducing _NOx emissions. .

Contents of the invention

(1) Technical problems to be solved

In view of this, the main purpose of the present invention is to provide a jet nozzle for a soft combustor of a gas turbine, which can achieve the goals of low pressure loss, high-efficiency mixing, low concentration of components near the wall surface of the outlet mixture, and low jet swirl number at the exit of the jet nozzle.

(2) Technical solution

The invention provides a jet nozzle of a soft combustor of a gas turbine, the jet nozzle includes a fuel inner nozzle, a fuel outer injection hole, a plurality of swirl groove passages, an outer pipe and an inner pipe, and the outer pipe is fixed on the combustion chamber head The front end of the inner pipe partially extends into the outer pipe, an annular passage is formed between the inner pipe and the outer pipe, the fuel internal nozzle is arranged in the inner pipe, and the multiple The two swirl groove channels are evenly distributed on the pipe wall of the inner pipe along the circumferential direction, the fuel outer injection hole is arranged on the pipe wall of the rear end of the inner pipe, and the rear end of the fuel inner nozzle is located at the fuel Between the outer spray hole and the swirl groove channel.

The inner air close to the jet nozzle enters the inner pipe through the swirl channel, and forms a first mixed gas with the fuel sprayed by the inner fuel nozzle in the inner pipe.

Part of the fuel is sprayed to the closed space at the head of the combustion chamber through the fuel outer injection hole, and is mixed with the outer air in the annular channel to form a lean second mixed gas. The first mixed gas and the second mixed gas are The outer pipeline is mixed into a weak-swirl mixed gas.

Preferably, the ratio of the area of the inner pipe to the sum of the areas of the inner pipe and the outer pipe is between 30-80%.

Preferably, the distance between the inner pipe and the outlet of the jet nozzle is 0.5-3.0 times the inner diameter of the inner pipe.

Preferably, the ratio of the fuel injected from the fuel outer injection hole to the sum of the fuel injected from the fuel inner nozzle and the fuel outer injection hole is between 0% and 50%.

Preferably, the number of swirl slot channels is M, and the swirl slot channels have a tangential swirl angle θ, where M≥4, 60°≥θ≥30°.

Preferably, the ratio of the sum of the cross-sectional areas of the swirl channels to the cross-sectional area of the inner pipe is in the range of 0.9-1.1.

Preferably, the inner diameter Do of the outer pipe is 25-35 mm, the distance L2 of the outer pipe protruding from the combustion chamber head baffle is 15-25 mm, and the distance L between the front end of the inner pipe and the outlet of the jet nozzle is 20 mm. -60mm.

Preferably, the inner diameter Di of the inner pipe is 20-25mm, the pipe wall thickness is 1-2mm, the distance L1 between the fuel inner nozzle and the front end of the inner pipe is 15-25mm, and the axial direction of the swirl channel is The height is 8-12mm.

Preferably, the internal fuel nozzle has a plurality of fuel injection holes, and the diameter of the fuel injection holes is 1.5-2.5 mm. Preferably, the number of the fuel injection holes is 3-6. Preferably, the The fuel outer injection holes are evenly distributed on the pipe wall of the inner pipe along the axial direction, and the number of the fuel outer injection holes is 2-4.

Preferably, the N jet nozzles are uniformly arranged on a circle centered on the center of the combustion chamber head, preferably, N≧3.

Preferably, the axes of the inner fuel nozzle, the outer pipe and the inner pipe are coincident.

(3) Beneficial effects

As can be seen from the foregoing technical scheme, the unit jet nozzle of the soft combustion chamber of the gas turbine of the present invention has the following beneficial effects:

(1) The mixing uniformity of fuel and air at the outlet of the jet nozzle is improved, and the fuel-air equivalent on the outside is relatively low, which is conducive to the improvement of the flame root and is not easy to catch fire prematurely;

(2) The jet flow of the jet nozzle belongs to weak rotation, the overall pressure loss is small, and the axial velocity is not easy to attenuate, which is beneficial to increase the flue gas return ratio of the combustion chamber;

(3) The jet nozzle is generally a weak swirling flow, which effectively reduces the pressure loss during the flow process, forms a recirculation zone downstream of the combustion chamber, and raises the height of the flame. At the same time, it forms a soft combustion downstream of the combustion chamber, reducing the pressure loss during the combustion process The peak flame temperature avoids thermoacoustic shock, and can achieve ultra-low nitrogen oxide emissions in a wide load range under the premise of ensuring the combustion efficiency and performance of the combustion chamber;

(4) The jet nozzle has a compact structure and can directly replace the jet nozzle of a gas turbine combustor with a similar structure, which is convenient for practical application and operation;

(5) For a variety of industrial fuel gases such as natural gas and coal-to-synthesis gas, the size and relative position of the main fuel nozzle and jet nozzle can be adjusted according to the fuel characteristics such as ignition delay time, flame propagation speed, and fuel calorific value of the fuel gas.

Description of drawings

Fig. 1 is the structural representation of general soft combustion chamber;

Fig. 2 is a schematic structural view of a jet nozzle according to an embodiment of the present invention;

Fig. 3 is a schematic structural view of the channel of the swirl tank.

Explanation of reference signs:

100 - soft combustion chamber;

110-combustion chamber flame tube; 120-duty swirl nozzle;

130-jet nozzle; 140-main fuel pipeline;

150-duty fuel pipeline; 160-combustion chamber casing;

170-combustion chamber head baffle; 180-combustion chamber transition section;

130-jet nozzle:

210-fuel inner nozzle; 220-fuel outer spray hole;

230-swirl tank channel; 240-outside pipeline;

250 - inner pipe; 260 - fuel injection hole.

θ-tangential swirl angle; L-the distance between the inner pipe and the outlet of the jet nozzle; L1-the distance between the front end of the fuel inner nozzle and the outlet of the inner pipe; L2-the distance from the jet nozzle protruding from the combustion head baffle; Di-the inner pipe Do-inner diameter of the outer pipe; Ai-inner air flowing into the inner pipe; Ao-outer air flowing in the outer pipe; Fi-fuel ejected from the inner nozzle of the fuel; Fo-fuel ejected from the outer nozzle hole of the fuel; H - the axial height of the channel of the swirl groove on the outer wall of the inner pipe.

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.

The invention provides a soft combustion chamber jet nozzle, and several jet nozzles are important components of the nozzle assembly of the combustion chamber head. The composition of the general soft combustion chamber is shown in Figure 1: soft combustion chamber 100, combustion chamber flame tube 110, duty swirl nozzle 120, jet nozzle 130, main fuel pipeline 140, duty fuel pipeline 150, combustion chamber casing 160, combustion chamber Chamber head baffle 170 and combustion chamber transition section 180.

As shown in Figure 2, the jet nozzle 130 of the present invention comprises a fuel inner nozzle 210, a fuel outer injection hole 220, a swirl channel 230, an outer pipeline 240 and an inner pipeline 250, and the outer pipeline 240 is fixed on the combustor head baffle 170 Above, the front end of the inner pipe 250 partially extends into the outer pipe 240, an annular channel is formed between the inner pipe 250 and the outer pipe 240, the fuel inner nozzle 210 is arranged in the inner pipe 250, and the swirl channel 230 is evenly distributed in the circumferential direction. On the pipe wall of the inner pipe 250 , the outer fuel injection hole 220 is arranged on the pipe wall at the rear end of the inner pipe 250 , and the rear end of the inner fuel nozzle 210 is located between the outer fuel injection hole 220 and the swirl channel 230 .

The inner air Ai close to the jet nozzle 130 enters the inner pipe 250 through the swirl channel 230 , and forms a first gas mixture with the fuel injected from the inner fuel nozzle 210 in the inner pipe 250 .

The outer air enters the nozzle through the annular channel. In order to enhance the mixing efficiency, part of the fuel is sprayed through the fuel outer injection hole 220 to the closed space at the head of the combustion chamber, and is mixed with the outer air Ao in the annular channel to form a thin second mixed gas. The first mixed gas The gas and the second mixed gas are mixed in the outer pipeline 240 to form a weak-swirl mixed gas. The fuel distribution in the center of the weak-swirled mixed gas is relatively uniform, and the fuel concentration near the wall of the outer pipeline 240 is relatively low.

By adjusting the inner diameter Di of the inner pipe 250 and the inner diameter Do of the outer pipe 240, the ratio of the area of the inner pipe 250 to the sum of the areas of the inner pipe 250 and the outer pipe 240 is between 30-80%.

In order to control the mixing uniformity at the outlet of the nozzle, the distance L between the inner pipe 250 and the outlet of the jet nozzle 130 is 0.5-3.0 times the inner diameter Di of the inner pipe 250 .

The ratio of the fuel Fo sprayed from the fuel outer injection hole 220 to the sum (Fo+Fi) of the fuel sprayed from the fuel inner nozzle 210 and the fuel outer injection hole 220 is between 0-50%.

As shown in Figure 3, the number of swirl groove passages 230 is M, and the swirl groove passage 230 has a tangential swirl angle θ, and the inner pipe 250 is connected with the gas collection chamber through the swirl groove passage 230, wherein M≥4 , 60°≥θ≥30°.

The range of the ratio of the sum of the cross-sectional areas of the swirl channel 230 to the cross-sectional area of the inner pipe 250 is 0.9-1.1.

The inner diameter Do of the outer pipe 240 is 25-35mm, the distance L2 of the outer pipe 240 protruding from the combustion chamber head baffle 170 is 15-25mm, and the distance L between the front end of the inner pipe 250 and the outlet of the jet nozzle is 20-60mm. Preferably, Do=30mm, L2=20mm, L=50mm.

The inner diameter Di of the inner pipe 250 is 20-25mm, the pipe wall thickness is 1-2mm, the distance L1 between the fuel inner nozzle 210 and the front end of the inner pipe 250 is 15-25mm, and the axial width of the swirl channel 230 is 8-12mm . Preferably, Di=22mm, L1=20mm, H=10mm, and the wall thickness of the inner pipe 250 is 1.5mm.

The fuel inner nozzle 210 has a plurality of fuel injection holes 260, and the diameter of the fuel injection holes 260 is 1.5-2.5mm. Preferably, the number of the fuel injection holes 260 is 3-6. Preferably, the fuel outer injection holes 220 are along the axis Evenly distributed on the pipe wall of the inner pipe 250, the number of fuel outer injection holes 220 is 2-4.

N jet nozzles are evenly arranged on a circle centered on the center of the combustion chamber head, preferably, N≥3.

The axes of the inner fuel nozzle 210, the outer pipe 240, and the inner pipe 250 coincide.

The outlet of the jet nozzle produces a low-pressure drop, low swirl, and evenly mixed fuel/air mixture. The fuel concentration of the mixture near the wall of the jet nozzle outlet is relatively low, and the jets of multiple jet nozzles form a return entrainment gas inside the combustion chamber. Facilitates the establishment of a soft burn.

In the combustor flame tube 110, the first recirculation zone formed by the nozzle assembly on duty is located at the downstream position of the outlet end of the nozzle assembly on duty, and the second recirculation zone formed by N jet nozzles 130 is located at the downstream position of the first recirculation zone, and the jet nozzles 130 burn The generated high-speed mixed gas entrains the surrounding high-temperature and low-oxygen mixture, and soft combustion is realized in the downstream area of the combustion chamber flame tube 110 .

As shown in FIG. 2 , when the soft combustion chamber jet nozzle of the embodiment of the present invention is working, Fi and Ai are mixed in the inner pipe of the nozzle, and Fo and Ao are mixed in the outer passage to form a relatively lean mixture. The inner mixture continues to mix with the outer mixture within a distance L after the outlet of the inner channel. Finally, a well-mixed high-speed low-swirl jet is formed. The high-speed mixture will not burn directly and quickly, which is conducive to improving the ignition point. The low-swirl jet composed of multiple jet nozzles forms a flue gas backflow in the combustion chamber, which increases the residence time of the flue gas. It ensures sufficient combustion and is conducive to the establishment of soft combustion, thereby achieving low NOx emissions. For a variety of industrial fuel gases such as natural gas and coal-to-synthesis gas, the inner and outer fuel (Fi, Fo) distribution can be adjusted according to fuel gas ignition delay time, flame propagation velocity, fuel calorific value, etc., and the inner and outer air (Ai, Ao) distribution, blending distance L, etc., can adapt to various industrial fuel gases.

In one embodiment, the velocity of the mixed gas outlet of the jet nozzle is set to be 80m/s-160m/s, the velocity of the main fuel nozzle is 120m/s-200m/s, and the high-temperature flue gas is injected by the jet nozzle jet and mixed with it efficiently , forming an unburned mixture with a temperature of 1200°C to 1700°C and an oxygen concentration of 5% to 10%, realizing soft combustion characterized by high temperature and low oxygen.

On the basis of realizing high-efficiency mixing, the present invention reduces nozzle pressure loss, reduces nozzle outlet swirl number, ensures flue gas recirculation ratio inside the combustion chamber, and then realizes soft combustion and reduces NOx emission.

It should be noted that, in the accompanying drawings or in the text of the specification, implementations that are not shown or described are forms known to those of ordinary skill in the art, and are not described in detail. In addition, the above definition of each element is not limited to the various specific structures and shapes mentioned in the embodiments, and those skilled in the art can easily modify or replace them, for example:

(1) The jet nozzle can also adopt other structures, as long as the same function can be completed;

(2) This document may provide examples of parameters containing specific values, but these parameters need not be exactly equal to the corresponding values, but may approximate the corresponding values within acceptable error tolerances or design constraints;

(3) The directional terms mentioned in the embodiments, such as "up", "down", "front", "back", "left", "right", etc., are only referring to the directions of the drawings, and are not used to limit The protection scope of the present invention;

(4) The above embodiments can be mixed and matched with each other or with other embodiments based on design and reliability considerations, that is, technical features in different embodiments can be freely combined to form more embodiments.

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. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included within the protection scope of the present invention.

Claims (10)

1. a kind of jet nozzle of the soft combustion chamber of gas turbine, including：Spray orifice, Duo Gexuan on the outside of fuel inwardly projecting orifice, fuel Launder channel, outside pipeline and inside pipeline, it is characterised in that：The outside pipeline is fixed on head of combustion chamber baffle, described The outside pipeline is stretched into the fore-end of inside pipeline, and it is logical that annular is formed between the inside pipeline and the outside pipeline Road, the fuel inwardly projecting orifice are arranged in the inside pipeline, and the multiple rotation launder channel is uniformly distributed circumferentially in institute State on the tube wall of inside pipeline, spray orifice is arranged on the tube wall of the inside pipeline rear end on the outside of the fuel, in the fuel The rear end of portion's nozzle is located on the outside of the fuel between spray orifice and the rotation launder channel.

2. jet nozzle as claimed in claim 1, it is characterised in that：The area of the inside pipeline and the inside pipeline and The ratio of the sum of the area of the outside pipeline is between 30-80%.

3. jet nozzle as claimed in claim 1, it is characterised in that：The distance that the inside pipeline is exported with jet nozzle is 0.5-3.0 times of the inside pipeline internal diameter.

4. jet nozzle as claimed in claim 1, it is characterised in that：The fuel that spray orifice sprays on the outside of the fuel and the combustion Expect the ratio of the sum of the fuel that spray orifice sprays on the outside of inwardly projecting orifice and the fuel between 0-50%.

5. jet nozzle as claimed in claim 1, it is characterised in that：The quantity of the rotation launder channel is M, the eddy flow Groove passage has tangential swirl angle θ, wherein a M >=4,60 ° >=θ >=30 °.

6. jet nozzle as claimed in claim 5, it is characterised in that：It is described rotation launder channel cross-sectional area sum with it is described The ratio between cross-sectional area of inside pipeline scope：0.9-1.1.

7. jet nozzle as claimed in claim 1, it is characterised in that：The internal diameter Do of the outside pipeline is 25-35mm, described The distance L2 that outside pipeline stretches out head of combustion chamber baffle is 15-25mm, and front end and the jet nozzle of the inside pipeline export Distance L be 20-60mm.

8. jet nozzle as claimed in claim 1, it is characterised in that：The internal diameter Di of the inside pipeline is 20-25mm, tube wall Thickness is 1-2mm, and the distance L1 of fuel inwardly projecting orifice and the front end of the inside pipeline is 15-25mm, the rotation launder channel Axial height be 8-12mm.

9. jet nozzle as claimed in claim 1, it is characterised in that：The fuel inwardly projecting orifice has multiple fuel jet orifices, A diameter of 1.5-2.5mm of the fuel jet orifice, the number of the fuel jet orifice is 3-6, it is preferable that the outer side spray of the fuel Hole is distributed on the tube wall of the inside pipeline vertically, and the number of spray orifice is 2-4 on the outside of the fuel.

10. jet nozzle as claimed in claim 1, it is characterised in that：N number of jet nozzle is uniformly arranged on combustion chamber Head center is on the circumference in the center of circle, it is preferable that N >=3.