WO2015072629A1 - Ultra-low nitrogen oxide combustion apparatus using internal recirculation of combustion gas and method therefor - Google Patents

Abstract

An ultra-low nitrogen oxide combustion apparatus according to the present invention comprises: a primary fuel jetting body; one or more secondary fuel jetting bodies; a recirculation guide unit; a fuel supply unit; an oxidant supply unit; and an air multistage sleeve. The primary fuel jetting body supplies main fuel into a combustion furnace. The one or more secondary fuel jetting bodies are arranged around the primary fuel jetting body in such a manner that the front ends thereof are inserted into the combustion furnace. The recirculation guide unit re-supplies combustion gas generated from the combustion furnace to the combustion furnace by hydrodynamic force. The fuel supply unit supplies fuel to the primary fuel jetting body and the secondary fuel jetting bodies. The oxidant supply unit supplies an oxidant to a gap between the primary fuel jetting body and the secondary fuel jetting bodies. The air multistage sleeve is arranged to surround the primary fuel jetting body for air multistage. The oxidant supplied from the oxidant supply unit is supplied in multiple stages through the internal and external portions of the air multistage sleeve. By applying an internal recirculation technique, the present invention can transmit combustion gas, generated in a combustion chamber including multiple flame areas, not to an external link pathway of the combustion chamber, but into the combustion chamber, without an additional separate device.

Description

Ultra low nitrogen oxide combustion apparatus through internal recirculation of combustion gas and its operation method

The present invention relates to an ultra-low nitrogen oxide combustion apparatus through internal recirculation of combustion gas, and more particularly, an internal combustion gas that is generated in a combustion chamber to be delivered without a separate device inside the combustion chamber instead of an external connection passage of the combustion chamber. The present invention relates to an ultra low nitrogen oxide combustion apparatus using a recycling technology.

At present, mankind's main energy source is hydrocarbon-based fossil fuels. However, the problem of environmental pollution by the product after combustion of fossil fuels has been seriously raised. The main environmental pollutants include nitrogen oxides (NOx) and carbon dioxide (CO ₂ ), as well as carbon monoxide (CO) and soot caused by incomplete combustion of fuels.

Combustors using conventional fossil fuels inevitably generate nitrogen oxides (NOx) having a chemical formula of NO and NO2 by chemical reactions during combustion. Low NOx combustion technology to suppress this occurrence is being developed to improve the structure of the combustor, such as the mixture of fuel and air, air-fuel ratio. Nitrogen oxides generated during the combustion process react with other oxygen in the atmosphere, causing environmental problems such as smog and increased ozone in the atmosphere. In particular, emissions from these combustion processes harm the environment and human health, so countries are tightening regulations on more and more stringent standards.

Types of nitrogen oxides may be classified into thermal NOx, prompt NOx, and fuel NOx depending on the cause. Thermal nitrogen oxides are produced by the reaction of nitrogen in the air with oxygen at a high temperature of 1600 ° C or higher, rapid nitrogen oxides are produced at the beginning of combustion during the combustion of hydrocarbon-based fuels, and fuel nitrogen oxides are reactions of nitrogen components contained in the fuel. Is generated by Even in such a countermeasure against nitrogen oxides, since gaseous fuels such as natural gas do not contain nitrogen in the fuel, it may be effective to control matters related to Thermal NOx and Prompt NOx.

Nitrogen oxides are known to cause photochemical smog and acid rain and seriously affect plants and animals. For many years, many researchers have studied various ways to reduce NOx.

Because of this, low NOx methods currently being tried include exhaust gas recirculation, water or steam injection, multistage combustion of air and fuel, selective non-catalytic reduction (SNCR), and selective catalytic reduction (SCR). catalytic reduction). Recently, developed countries have tried to re-burn NOx in the post-combustion area, and are known to have high efficiency in terms of NOx reduction rate and economic efficiency.

As a conventional method for reducing NOx as described above, the Republic of Korea Patent Publication No. 10-2005-0117417 can be exemplified. In step 10-2005-0117417, in order to reduce the amount of nitrogen oxides (NOx) generated, combustion air is supplied in three stages by mixing general air and exhaust gas, but by varying the mixing ratio of each stage. The present invention provides a three-stage burner for exhaust gas recirculation for liquid and gas to minimize local high temperature generation by combustion and to extend the combustion zone to achieve uniform heating in the boiler.

On the other hand, in the above-mentioned literature, the exhaust gas is re-introduced into the combustion furnace by providing a plurality of exhaust gas supply pipes, a recirculation duct, and a damper as elements for recycling the exhaust gas, but separately from the outside of the combustion furnace. There is a disadvantage that the required space is increased because it must be installed.

Meanwhile, referring to registered patent No. 1203189 filed by the inventor, the internal recirculation technology is provided so that the combustion gas generated in the combustion chamber is delivered without a separate device inside the combustion chamber, not the external connection passage of the combustion chamber. There is a limitation in that a specific configuration for forming a lean flame in the center of a combustion furnace or a description of specific factors that can reduce the formation of nitrogen oxides is insufficient.

In order to solve the above problems, the present invention allows the oxidant to be supplied to the central region of the combustion furnace, and at the same time, the combustion gas generated in the combustion chamber in which the multiple flame fields are formed is separated in the combustion chamber instead of the external connection passage of the combustion chamber. It is an object of the present invention to provide an ultra low nitrogen oxide combustion apparatus employing an internal recirculation technology that can be delivered without.

In addition, an object of the present invention is to form a flame field of high efficiency and low pollution structure through a multi-stage fuel supply nozzle structure consisting of a primary fuel injector for supplying the main fuel and a secondary fuel injector for supplying the auxiliary fuel.

In order to solve the above problems, the ultra low nitrogen oxide combustion apparatus according to the present invention includes a primary fuel injector for supplying the main fuel into the combustion furnace; At least one secondary fuel injector disposed around the primary fuel injector, the leading end of the secondary fuel injector being arranged to enter the interior of the combustion furnace; A recycling induction unit configured to recycle the combustion gas generated in the combustion furnace to the combustion furnace by a hydrodynamic force; A fuel supply unit supplying fuel to the primary fuel injector and the secondary fuel injector; An oxidant supply unit supplying an oxidant to a space between the primary fuel injector and the secondary fuel injector; And an air multistage sleeve disposed to surround the primary fuel injector for air multistage, wherein the oxidant supplied from the oxidant supply unit is supplied to the multistage through the inside and the outside of the air multistage sleeve.

When the diameter of the discharge port of the primary fuel injector is defined as B, the diameter of the air multistage sleeve is defined as D, and the inner diameter of the recirculation induction part is defined as C, the first performance index indicating the premixed strength, η ₁ is It may be preferable to set to.

The value of the first figure of merit may be in the range of 0.3 to 0.5.

The ultra low nitrogen oxide combustion apparatus, a swirler disposed at the front end of the primary fuel injector; And a central oxidant injector for transferring the oxidant supplied from the oxidant supply unit into the combustion furnace along the inside of the primary fuel injector.

When defining the discharge port diameter of the primary fuel injector as B and the diameter of the swirler as A, a second performance index indicating a nozzle shape coefficient, η ₂ is set by the following equation, It may be desirable for the value to be in the range of 1.5 to 2.0.

When defining the outlet diameter of the primary fuel injector as B, the diameter of the swirler as A, and the inner diameter of the recycle induction part as C, a third performance index indicating a swirl flow coefficient, η ₃ is set by the following equation. It may be preferable that the value of the third performance index is in the range of 0.55 to 0.75.

When defining the distance between the FIR ports as E and the diameter of the fuel pipe as E, it may be preferable that the fourth performance index, η ₄ , representing the recycle flow velocity, is set by the following equation.

When defining the outlet diameter of the primary fuel injector as B and the inner diameter of the recirculation induction part as C, it may be preferable that the fifth performance index, η ₅ , representing the combustor outlet flow rate, is set by the following equation.

The ultra-low nitrogen oxide combustion apparatus further includes a recirculation promoting protrusion disposed on an outer surface of the air multistage sleeve, wherein the recirculation promoting protrusion increases a flow rate of the combustion gas flowing between the recirculation induction portion and the air multistage sleeve. It may be desirable.

The secondary fuel injector may be disposed in plural to maintain a constant interval on the same circumference around the primary fuel injector, and the secondary fuel injector may inject fuel in a radial direction thereof. have.

It may be desirable for the radial injection angle of the secondary fuel injector to inject fuel between an angle toward the adjacent secondary fuel injector and an angle toward the alternately adjacent secondary fuel injector.

It is preferable that the axial fuel injection angle of the secondary fuel injector is in the range of 10 ° to 80 °.

Fuel injection speed of the primary fuel injector;

Is preferably set in the range of 20 to 50.

Fuel injection velocity of secondary fuel injector,

Is preferably set in the range of the following formula.

The recirculation induction part may change the direction of movement of the combustion gas flowing in connection with an internal recirculation sleeve disposed obliquely based on the secondary fuel injector, a connection guide extending from a rear end of the internal recirculation sleeve, and a rear end of the connection guide. It may be desirable to include a spray nozzle.

The injection nozzle may be inclinedly disposed between the primary fuel injector and the recycle induction part to reduce the width between the primary fuel injector and the recycle induction part, which is a flow space of the oxidant.

The primary fuel injector may be preferable to inject the main fuel supplied in the radial and tangential direction.

It may be preferable that the front end of the secondary fuel injector is arranged to enter the interior of the combustion furnace more than the front end of the primary fuel injector.

The primary fuel injector forms a primary space, which is a fuel rich region, in the combustion furnace, and the secondary fuel injector forms a secondary space, a fuel lean region, at a rear end of the primary space. It may be desirable to form

The ultra low nitrogen oxide combustion apparatus according to the present invention allows the combustion gas generated in the combustion chamber in which the multiple flame fields are formed to be delivered without an additional device inside the combustion chamber instead of the external connection passage of the combustion chamber by applying an internal recirculation technology.

By optimizing the shape of the internal recycle derivative, the combustion gas in the furnace is mixed with an oxidant sucked by thermal and hydrodynamic induction technology without external power, thereby enabling ultra low nitrogen oxide operation.

The present invention provides an air supply process for forming lean flames by supplying oxidants to the flame center or prevents increased nitrogen oxide production by localized hot spots at the flame center. This suppresses overheating of the swirler and fuel injector tip.

In addition, the present invention enables the smooth recirculation flow of the combustion gas generated in the combustion furnace through the structure of the recirculation induction section and the air multi-stage sleeve, so that the flame of the flame due to the flow against the recirculation flow of the center, which is important for the conventional flame Prevents instability from occurring

In addition, a separate power supply device is not required, thereby simplifying the installation and increasing the circulation efficiency of the combustion gas.

In addition, the present invention undergoes a process in which the combustion gas passing through the recirculation induction part is resupplied to the combustion furnace together with the oxidant and combusted to achieve a stable flame.

1 is an overall configuration of an ultra low nitrogen oxide combustion apparatus according to a first embodiment of the present invention,

FIG. 2 is a view of the combustion apparatus of FIG. 1 viewed from the inside of a combustion furnace, and illustrates an embodiment in which auxiliary fuel is injected from a secondary fuel injector; FIG.

FIG. 3 is a view of the combustion apparatus of FIG. 1 viewed from the inside of a combustion furnace, and shows another embodiment in which auxiliary fuel is injected from a secondary fuel injector; FIG.

4 is a diagram illustrating symbols constituting a significant figure of merit;

5a to 5f are graphs showing the important performance index of the ultra-low nitrogen oxide combustion apparatus of the present invention;

6 is an overall configuration diagram of an ultra low nitrogen oxide combustion apparatus according to a second embodiment of the present invention, and

It is a figure explaining the axial fuel injection angle of a secondary fuel injector.

The above objects, features and other advantages of the present invention will become more apparent by describing the preferred embodiments of the present invention in detail with reference to the accompanying drawings. The described embodiments are provided by way of example for purposes of illustration, and do not limit the technical scope of the present invention.

Each component constituting the ultra low nitrogen oxide combustion apparatus of the present invention may be used integrally or separately separated as necessary. In addition, some components may be omitted depending on the form of use.

Hereinafter, an ultra low nitrogen oxide combustion apparatus according to an embodiment of the present invention will be described in detail with reference to the accompanying drawings.

Overall composition of the ultra low nitrogen oxide combustion device

First, the overall configuration of the ultra low nitrogen oxide combustion apparatus 100 according to the first embodiment of the present invention will be described with reference to FIG. 1.

The ultra low nitrogen oxide combustion apparatus 100 surrounds the primary fuel injector 10 and the primary fuel injector 10 disposed in the center of the opening formed in front of the combustion furnace 1, and closely adheres to the inside of the opening. Disposed between the secondary fuel injector 20, the swirler 30 disposed at the tip of the primary fuel injector 10, the primary fuel injector 10 and the secondary fuel injector 20 The recycling induction part 40, the primary fuel injector 10, and the air multistage sleeve 60 disposed to surround the swirler 30, and the recirculation promoting protrusion 90 disposed on the outer surface of the air multistage sleeve 60. ). The recycle induction part 40 is disposed adjacent to the secondary fuel injector 20.

The primary fuel injector 10 includes a transfer part 13 connected to the first fuel line 51 and an enlarged part 11 directly connected to the transfer part 13. The transfer part 13 is for safely transporting the main fuel to the enlarged part 11, preferably made of a durable material, and may have a uniform diameter.

In one embodiment, the enlarged portion 11 may have a shape in which its diameter gradually increases, and injects the supplied main fuel through its outer circumferential surface. That is, fuel entering the enlarged portion 11 through an injection hole (not shown) formed on the outer circumferential surface of the expanded portion 11 is radially injected into the internal space between the fuel injectors 10 and 20 (see FIG. 1). See reference numeral 15). That is, the fuel in the enlarged portion 11 is injected along the radial direction of the enlarged portion 11 on the oxidant introduced.

Meanwhile, the central oxidant injector 85 may be disposed along the inside of the primary fuel injector 10. Here, the nozzle can be inserted into the end of the central oxidant injection unit 85 to control the air supply amount. The central oxidant injector 85 allows the oxidant supplied from the oxidant supply unit 80 to flow along the central axis of the primary fuel injector 10, and then, as the flame center of the combustion furnace 1, the primary space 72. Have it supplied.

This promotes the mixing effect of the flame and the oxidant in the primary space 72, which is the flame center, thereby suppressing the formation of red salts, thereby inducing the formation of blue salts. In addition, the generation of nitrogen oxides is reduced by reducing the local high temperature region around the flame center.

The secondary fuel injectors 20 are arranged at regular intervals on the same circumference with respect to the primary fuel injectors 10. Specifically, six to twelve secondary fuel injectors 20 are arranged, and preferably eight secondary fuel injectors 20 are arranged at equal intervals. The tip of the secondary fuel injector 20 is arranged to further enter the interior of the combustion furnace 1 as compared to the tip of the primary fuel injector 10. The tip structure of the secondary fuel injector 20 may be inclined in one direction to be inclined. Specifically, it may be determined to be inclined in a form gradually away from the opening 3 in the direction toward the center of the combustion furnace 1.

Fuel injected from the secondary fuel injector 20 may be injected in a radial direction of the secondary fuel injector 20. The secondary fuel injector 20 causes the auxiliary fuel to be injected in the radial direction instead of the axial direction to generate a rotational flow in the combustion furnace 1. In the present invention, the auxiliary fuel may be discharged in a clockwise or counterclockwise direction on the circumference of the plurality of secondary fuel injectors 20 (see reference numeral 25 of FIG. 2 or reference numeral 25 'of FIG. 3). As an example, the figure shows the form sprayed clockwise.

In the present invention, the fuel injection direction from any one of the plurality of secondary fuel injectors 20 is set to face another adjacent secondary fuel injector 20 (see FIG. 2). On the other hand, as another embodiment, the fuel injection direction from any one of the plurality of secondary fuel injectors 20 is set to face the alternately adjacent other secondary fuel injectors 20 (see FIG. 3). On the other hand, the radial injection angle from any one of the plurality of secondary fuel injectors 20 is determined between the angle toward the adjacent secondary fuel injector and the angle toward the alternately adjacent secondary fuel injector. Can be sprayed.

In FIG. 3, the fuel is injected only from four secondary fuel injectors 20 out of the eight secondary fuel injectors 20 arranged, but this is to clearly indicate the injection direction. It is assumed that fuel is injected from the carcass 20.

The primary fuel injector 10 and the secondary fuel injector 20 are both configured as hollow cylindrical tubes. The oxidant is supplied from the oxidant supply unit 80 to the space between the primary fuel injector 10 and the secondary fuel injector 20. The oxidant is supplied into the combustion furnace 1 directly through the swirler 30 with the axial or tangential momentum formed therein, or directly through the swirler 30.

Liquid fuel is divided into primary fuel and secondary fuel from the fuel supply unit 50 to the primary fuel injector 10 and the secondary fuel injector 20. After the impurities are removed from the fuel supply unit 50 through a filter (not shown) and pumped by a pump (not shown), the fuel injectors 10 and 20 are branched to the first line 51 and the second line 52. ) Solenoid valves 55 and 56 may be installed in the lines 51 and 52, respectively, to properly supply and shut off the liquid fuel supplied to the main fuel and the secondary fuel.

The swirler 30 is disposed at the front end of the primary fuel injector 10 so that the premixer can be supplied diagonally to the axial direction of the primary fuel injector 10. In addition, the premixer supplied in an oblique line makes a swirl flow and enables the generation of vortices (see reference numeral 32 in FIG. 2). In order to implement the above functions, the swirler 30 may include a hollow cylindrical body and a wing-shaped guide plate disposed diagonally with respect to the axial direction inside the body. Inside the body is formed a hollow cylindrical insertion hole (not shown) connected to one side end of the guide plate. As the primary fuel injector 10 penetrates and is fixed to the insertion hole, the swirler 30 is disposed to surround the front end of the primary fuel injector 10.

The recirculation induction part 40 is an internal recirculation sleeve 41 and an internal recirculation sleeve 41 which are disposed to be inclined relative to the secondary fuel injector 20 on an opening (not shown) of the combustion furnace 1. The inclined member inclined at an inner lower end of the connection guide 43 extending from the connection guide, the injection nozzle 45 connected to the rear end of the connection guide 43 to change the moving direction of the flowing combustion gas, and the recirculation induction part 40. And (47).

The inner recirculation sleeve 41 is disposed to be inclined toward the center of the opening 3 from the front end to the rear end, which is the first inlet of the combustion gas. That is, the inner width becomes wider toward the rear end of the inner recirculation sleeve 41. The connecting guide 43 maintains a constant width as to allow a gentle flow of the combustion gas introduced through the inner recirculation sleeve 41.

The injection nozzle 45 injects the combustion gas flowing in the combustion furnace 1 through the internal recycling sleeve 41 and the connection guide 43 into the space between the primary fuel injector 10 and the recycling induction part 40. Let's do it. The injected combustion gas flows into the combustion furnace 1 together with the oxidant. The injection nozzle 45 is inclined between the primary fuel injector 10 and the recirculation induction part 40. That is, the orifice-shaped structure is realized by reducing the width between the primary fuel injector 10 and the recycling induction part 40. The arrangement of the injection nozzles 45 as described above allows the flow rate of the oxidant supplied to the space between the primary fuel injector 10 and the secondary fuel injector 20 to be increased into the combustion furnace 1 at a high speed. Let it flow

That is, since the space between the primary fuel injector 10 and the injection nozzle 45 becomes narrow, Bernoulli's theorem increases the flow rate of the oxidant. Through such a structure, the flow generated in the combustion furnace 1 enables an increase in momentum.

The inclined member 47 is a structure that is disposed on the boundary between the connection guide 43 and the injection nozzle 45 to adjust the width through which the combustion gas can flow, thereby adjusting the flow rate.

The air multistage sleeve 60 is a hollow cylindrical structure configured to separately supply the oxidant supplied from the oxidant supply unit 80 to the inside and the outside of the air multistage sleeve 60, thereby enabling the multistage supply of the oxidant. As a result, it is easy to form a multi-stage flame inside the combustion furnace 1.

The recirculation promoting protrusion 90 is disposed on the outer circumferential surface of the air multistage sleeve 60. Specifically, the recirculation promoting protrusion 90 performs a function of narrowing the space between the injection nozzle 45 and the air stage sleeve 60 constituting the recirculation induction part 40. Through the above structure, the flow rate of the combustion gas flowing through the recirculation induction part 40 from the combustion furnace 1 is increased while passing near the recirculation promoting protrusion 90. This prevents the separation of the combustion gas re-introduced into the combustion furnace 1 through the recirculation induction part 40, and consequently promotes the recirculation of the combustion gas.

Next, with reference to Figures 4 to 5E, the critical performance index that can determine the performance of the ultra-low nitrogen oxide combustion apparatus 100 will be described.

Symbols used in the formula for determining the significant performance index is defined as follows.

A: diameter of swirler 30, B: diameter of fuel head, C: internal diameter of recirculation induction part 40, D: diameter of air multistage sleeve 60, E: distance between FIR ports, F: fuel Diameter of pipe

Here, the diameter of the fuel head is the diameter of the discharge port of the primary fuel injector 10 and the diameter of the portion of the enlarged portion 11 coupled to the swirler 30, and the diameter of the fuel pipe is the primary fuel portion. The diameter of the conveying part 13 into which fuel flows in the carcass 10 and the distance between the FIR ports means the distance between the injection nozzles 45 of the recirculation induction part 40.

First, the first performance index, η ₁ indicates the premixed strength, and can be set by the following equation.

The first figure of merit refers to the ratio of the internal burner area to the total oxidant feed area and represents the ratio of the premixed air area to the pure oxidant supply area.

Referring to FIG. 5A, in the present invention, the value of the first index of performance is in the range of 0.3 to 0.5 to maintain the generation rate of nitrogen oxide at 20 or less. Preferably 0.4.

Next, 2nd performance index, (eta) ₂ shows a nozzle shape coefficient, and can be set with the following formula.

The second performance index refers to the ratio between the swirler diameter and the fuel head diameter and is used as a design index of the rapid premix burner head.

Referring to FIG. 5B, in order to maintain the incidence of nitrogen oxides at 20 or less in the present invention, the value of the second performance index is preferably in the range between 1.5 and 2.0.

Next, the third performance index, η ₃ , represents the swirl flow coefficient and can be set by the following equation.

The third performance index refers to the ratio of the swirl area to the total oxidant supply area, and may indicate the turning strength as the ratio of the area occupied by the swirler in the total oxidant supply area.

Referring to FIG. 5C, in order to maintain the incidence rate of nitrogen oxide at 20 or less, the value of the third performance index may be present in a range of 0.55 to 0.75. Preferably about 1.42.

Next, the fourth performance index, η _4, indicates the recycle flow rate, and can be set by the following equation.

The fourth performance index means the flow rate through the area excluding the area of the transfer part 13 among the areas between the ends of the injection nozzle 45.

Referring to FIG. 5D, in the present invention, the value of the fourth performance index is in the range of 45 to 60 to maintain the generation rate of nitrogen oxide at 20 or less.

Next, the fifth performance index, eta _5, represents the combustor outlet flow rate, and can be set by the following equation.

The fifth performance index means a flow rate through an area excluding the area of the fuel head among the inner areas of the connection guide 43.

Referring to FIG. 5E, in order to maintain the incidence rate of nitrogen oxide at 20 or less, the value of the fifth performance index is in the range of 30 to 50.

Here, the fuel injection speed of the primary fuel injector

Is preferably set in the range of 20 to 50.

And the fuel injection speed of the secondary fuel injector

Is preferably set in the range of the following formula.

Meanwhile, referring to FIG. 1, the fuel injected from the secondary fuel injector 20 has a θ value between 10 ° and 80 ° with respect to a plane perpendicular to the axial direction of the secondary fuel injector 20. It may be desirable to spray in the range.

Next, the sixth performance index, η ₆ indicates a premixing ratio, and can be set by the following equation.

The sixth performance index means the ratio of the premixed fuel flow rate to the total fuel flow rate.

Referring to FIG. 5F, in the present invention, the value of the sixth index of performance is in the range of 4 to 22 in order to maintain the generation rate of nitrogen oxide at 20 or less. As can be seen from the above, the lower the premixing ratio may be better nitrogen oxide reduction effect, but there is a disadvantage that the flame instability occurs in less than 5% conditions.

On the other hand, the present invention may proceed in consideration of the fuel speed and the shape of the head as an additional figure of merit, but there may be a limitation in including the shape of all the fuel head.

Next, the overall configuration of the ultra low nitrogen oxide combustion apparatus 200 according to the second embodiment of the present invention will be described with reference to FIG. 6.

In the following description, the same parts will be omitted from the ultra-low nitrogen oxide combustion apparatus 100 according to the first embodiment, and different parts will be mainly described.

In the ultra-low nitrogen oxide combustion apparatus 200, the air multistage sleeve 60 is removed differently from the first embodiment 100, while the recirculation promoting protrusion 90 'is provided with a transfer part of the primary fuel injector 10 ( It is characterized in that it is disposed on the outer peripheral surface of 13).

That is, the oxidant supplied to the outside of the primary fuel injector 10 is mixed with the combustion gas passed through the recirculation induction part 40 without flowing through the multistage sleeve 60 and flows toward the combustion furnace 1. do.

As described above, the low nitrogen oxide combustion apparatus 200 according to the second embodiment differs only in the arrangement position of the air multistage sleeve 60 and in the arrangement position of the recirculation promoting protrusion 90 ′. In terms of supplying an oxidant and re-feeding the combustion gas flowing in the combustion furnace 1 through the recirculation induction part 40 back to the combustion furnace 40, the core technical features are shared.

Explanation of Multistage Combustion Process of Ultra-low Nitrogen Combustor

Next, referring to FIG. 1 again, the multi-stage fuel combustion process of the present invention will be described.

First, the oxidant is supplied through the oxidant supply unit 80, and some of the supplied oxidant flows through the central oxidant injector 85 inside the primary fuel injector 10. At the same time, fuel is supplied from the fuel supply unit 50 to the primary fuel injector 10 via the first fuel line 51.

The main fuel flowing in the primary fuel injector 10 undergoes a radial injection through the outer circumferential surface of the enlarged portion 11, and the injected main fuel reacts with the oxidant to pre-mix the region ( 78). Here, since the enlarged portion 11 has a shape that is enlarged toward the combustion furnace 1 direction, it is possible to form the premixed region 78 over a large portion of the injected fuel.

The premixer formed in the premixing region 78 is discharged to the combustion furnace 1 through the swirler 30 to form the primary space 72. Analyzing the air supplied to the primary space 72 is as follows. The premixer formed in the premixing region 78 is transferred into the furnace 1 through the swirler 30 with axial momentum and tangential momentum.

In the above process, the combustion gas passing through the recirculation induction part 40 is supplied to the primary space 72 together with the premixer. The combustion gas discharged from the recirculation induction part 40 to the flow space of the oxidant is increased by the recirculation promoting protrusion 90 so as to increase the flow rates of the combustion gas and the oxidant, and prevent peeling. Through the above process, the premixer and the combustion gas enter the primary space 72 to undergo a process of burning, thereby achieving a stable flame. The primary space 72 is the main flame space region where at least about 50% of fuel is injected and combusted.

Next, fuel is supplied from the fuel supply unit 50 to the secondary fuel injector 20 via the second fuel line 52. The auxiliary fuel injected into the upper side of the primary space 72 through the secondary fuel injector 20 forms the secondary space 74 through a process of reacting with the unreacted oxidant in the primary space 72. . Some of the combustible gas in the primary space 72 is mixed with the premixer supplied to the outside of the swirler 30 to move to the wake of the primary flame to form a fuel lean flame. The fuel lean flame forms a secondary space 74.

As described above, in the present invention, the main fuel injected along the radial direction of the primary fuel injector 10 is premixed with the oxidizing agent to form a premixed region 78, and the combustion furnace from the premixed region 78 is fired. The premixer supplied in (1) forms the primary space 72, and injects the auxiliary fuel from the secondary fuel injector 20 to the rear end of the primary space 72 so as to form the final flame.

As described above, the multi-stage flame space is formed in the combustion furnace 1 by the fuel injected by the primary fuel injector 10 and the secondary fuel injector 20. At the rear end of the primary space 72, a secondary space 74 is created. The secondary space 74 is formed in a shape surrounding the primary space 72 in the space further entered into the inner side of the combustion furnace 1.

On the other hand, a self-recirculation region 76 is formed in the combustion furnace 1 separately from the multi-stage flame space including the primary and secondary spaces 72 and 74. The magnetic recirculation region 76 is formed at the inner edge region of the combustion furnace 1 so that combustion gas may flow in a vortex form.

The fuel injected from the primary fuel injector 10 forms the primary space 72, which is a stable fuel rich region, by the multi-stage air flow in the combustion furnace 1, and in the secondary fuel injector 20. The injected fuel undergoes a partial oxidation reaction by the atmospheric temperature and residual oxygen caused by the heat transferred from the primary flame of the primary fuel injector 10, and is converted into various combustible gas species so that the flame is in a fuel lean state after the flame. The secondary space 74 which is a space is comprised. Therefore, the flame state composed of multiple stages in the combustion furnace including the fuel rich region and the fuel lean region is clearly formed.

The flame of the ultra-low nitrogen oxide combustion apparatus 100 to which this principle is applied is basically a form in which the fuel rich and the fuel lean region are clearly distinguished, thereby minimizing the local high temperature region in the flame to suppress thermal NOx generation as much as possible. In addition, the combustion gas generated in the combustion furnace 1 through the recirculation induction part 40 is re-introduced into the combustion furnace 1 together with the oxidant to react without requiring a separate power, thereby reacting the fuel NOx by oxidation of nitrogen components in the fuel. The production can be reduced at source.

As described above, the ultra-low nitrogen oxide combustion apparatus of the present invention allows the combustion gas generated in the combustion chamber in which the multiple flame fields are formed to be transmitted without using a separate device inside the combustion chamber instead of the external connection passage of the combustion chamber by applying an internal recirculation technology.

In the present invention, the pre-mixer is formed through a method of injecting the main fuel into the flame in the axial direction of the fuel injector injected into the combustion furnace, but in the radial or tangential direction, and having the premixer formed therein. By forming the flame-type initial salt, it is possible to remove the high temperature reaction zone formed in the diffusion flame type initial salt in the conventional fuel multi-stage combustor.

In addition, the present invention undergoes a process in which the combustion gas passing through the recirculation induction part is resupplied and combusted together with the oxidant to increase the heat capacity of the flame to stably lower the temperature of the flame.

While preferred embodiments of the present invention have been described above, the present invention is not limited to the above-described specific embodiments. That is, those skilled in the art to which the present invention pertains can make many changes and modifications to the present invention without departing from the spirit and scope of the appended claims, and all such appropriate changes and modifications are possible. Equivalents should be considered to be within the scope of the present invention.

Claims (22)

1. Primary fuel injector for supplying the main fuel into the combustion furnace;

   At least one secondary fuel injector disposed around the primary fuel injector, the leading end of the secondary fuel injector being arranged to enter the interior of the combustion furnace;

   A recycling induction unit configured to recycle the combustion gas generated in the combustion furnace to the combustion furnace by a hydrodynamic force;

   A fuel supply unit supplying fuel to the primary fuel injector and the secondary fuel injector;

   An oxidant supply unit supplying an oxidant to a space between the primary fuel injector and the secondary fuel injector;

   A central oxidant injector for transferring an oxidant supplied from the oxidant supply unit into the combustion furnace along the inside of the primary fuel injector; And

   An air multistage sleeve disposed to surround the primary fuel injector for air multistage;

   The oxidant supplied from the oxidant supply unit is characterized in that it is supplied in multiple stages through the inside and outside of the air casing sleeve,

   Ultra low nitrogen oxide combustion device.
2. The method of claim 1,

   When defining the diameter of the discharge port of the primary fuel injector B, the diameter of the air multistage sleeve D, the internal diameter of the recirculation induction portion C,

   The first performance index, η ₁ indicating the premixed strength, is set by the following equation,

   Ultra low nitrogen oxide combustion device.

   
3. The method of claim 2,

   Characterized in that the value of the first performance index is in the range of 0.3 to 0,5,

   Ultra low nitrogen oxide combustion device.
4. The method of claim 1,

   The ultra low nitrogen oxide combustion device,

   And a swirler disposed at the tip of the primary fuel injector.

   Ultra low nitrogen oxide combustion device.
5. The method of claim 4, wherein

   When defining the discharge port diameter of the primary fuel injector B and the diameter of the swirler A,

   The second performance index, η ₂ , representing the nozzle shape coefficient, is set by the following equation,

   Characterized in that the value of the second performance index is in the range of 1.5 to 2.0,

   Ultra low nitrogen oxide combustion device.

   
6. The method of claim 4, wherein

   When defining the diameter of the discharge port of the primary fuel injector B, the diameter of the swirler A, and the internal diameter of the recirculation induction part C,

   The third performance index, η ₃ representing the swirl flow coefficient, is set by the following equation,

   Characterized in that the value of the third performance index is in the range of 0.55 to 0.75,

   Ultra low nitrogen oxide combustion device.

   
7. The method of claim 4, wherein

   When you define E as the distance between the FIR ports and E as the diameter of the fuel pipe,

   The fourth performance index, η ₄ , representing the recycle flow rate, is set by the following equation,

   Characterized in that the value of the fourth performance index is in the range of 45 to 60,

   Ultra low nitrogen oxide combustion device.

   
8. The method of claim 4, wherein

   When defining the discharge port diameter of the primary fuel injector B, and the inner diameter of the recirculation induction part C,

   The fifth performance index indicating the combustor outlet flow rate, η ₅ is set by the following equation,

   Characterized in that the value of the fifth performance index is in the range of 30 to 50,

   Ultra low nitrogen oxide combustion device.

   
9. The method of claim 4, wherein

   The ultra low nitrogen oxide combustion device,

   Further comprising: a recycling promoting projection that is attached to the outer surface of the air multi-stage sleeve,

   The recycle promotion protrusion is characterized in that for increasing the flow rate of the combustion gas flowing between the recycle induction portion and the air cascade sleeve,

   Ultra low nitrogen oxide combustion device.
10. The method of claim 1,

    A plurality of secondary fuel injectors are arranged to maintain a constant interval on the same circumference around the primary fuel injector, the secondary fuel injector is characterized in that for injecting fuel in the radial direction ,

    Ultra low nitrogen oxide combustion device.
11. The method of claim 10,

    The radial injection angle of the secondary fuel injector is characterized in that for injecting fuel between the angle toward the adjacent secondary fuel injector and the angle toward the alternately adjacent secondary fuel injector,

    Ultra low nitrogen oxide combustion device.
12. The method of claim 10,

    The fuel from the secondary fuel injector is injected between 10 ° to 80 ° with respect to the plane perpendicular to the axial direction of the secondary fuel injector,

    Ultra low nitrogen oxide combustion device.
13. The method of claim 10,

    The primary fuel injector is characterized in that for injecting the main fuel supplied in the radial and tangential direction,

    Ultra low nitrogen oxide combustion device.
14. The method of claim 13,

    Injection speed of fuel injected through the primary fuel injector

    

    Is characterized in that to inject fuel between 20 to 50m / s,

    Ultra low nitrogen oxide combustion device.
15. The method of claim 14,

    Injection rate of fuel injected through the secondary fuel injector

    

    Is set by the following formula,

    Ultra low nitrogen oxide combustion device.

    
16. The method of claim 10,

    The recirculation induction part may change the direction of movement of the combustion gas flowing in connection with an internal recirculation sleeve disposed obliquely based on the secondary fuel injector, a connection guide extending from a rear end of the internal recirculation sleeve, and a rear end of the connection guide. Characterized in that it comprises a spray nozzle,

    Ultra low nitrogen oxide combustion device.
17. The method of claim 16,

    The injection nozzle is inclined between the primary fuel injector and the recirculation induction part to reduce the width between the primary fuel injector and the recirculation induction part, which is the flow space of the oxidant,

    Ultra low nitrogen oxide combustion device.
18. The method of claim 10,

    The primary fuel injector is characterized in that for injecting the main fuel supplied in the radial and tangential direction,

    Ultra low nitrogen oxide combustion device.
19. The method of claim 10,

    The front end of the secondary fuel injector is characterized in that it is arranged to enter further into the combustion furnace than the front end of the primary fuel injector,

    Ultra low nitrogen oxide combustion device.
20. The method of claim 10,

    The primary fuel injector forms a primary space, which is a fuel rich region, in the combustion furnace, and the secondary fuel injector forms a secondary space, a fuel lean region, at a rear end of the primary space. Characterized in that,

    Ultra low nitrogen oxide combustion device.
21. The method of claim 20,

    The following expression representing the ratio of the fuel flow rate of the primary fuel injector to the fuel flow rate of the secondary fuel injector is the sixth performance index, η ₆ represents the premixing ratio, and is operated in the range of 4 to 22. Made,

    Ultra low nitrogen oxide combustion device.

    
22. In the method for operating the combustion device according to claim 1,

    (a) supplying an oxidant supplied from an oxidant supply through an air cascade sleeve to a combustion furnace;

    (b) supplying an oxidant from the oxidant supply unit into the combustion furnace through a central oxidant injection unit;

    (c) supplying fuel from the fuel supply unit to the primary fuel injector;

    (d) recirculating the combustion gas in the furnace to the furnace by hydrodynamic forces through a recycle induction;

    (e) supplying fuel from the fuel supply unit to a secondary fuel injector; And

    (f) forming a multi-stage flame space in the combustion furnace by fuel injected by the primary fuel injector and the secondary fuel injector.

    Operation method of the combustion device.

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