KR101733611B1 - Ultra-low NOx burner through internal recirculation of combustion gas and multi-fuel operation - Google Patents

Abstract

The present invention relates to a low nitrogen oxide combustion apparatus for effectively reducing the nitrogen oxide contained in a combustion gas by effectively recirculating a combustion gas produced by feeding and combustion of an efficient fuel multi-stage into a combustion furnace, The combustion apparatus includes a combustor having a combustor positioned so as to penetrate a predetermined distance into the combustion furnace, wherein the combustor has a primary fuel supply unit located on the inside of the combustion furnace and a combustion chamber on the side of the combustion furnace of the primary fuel supply unit A fuel supply unit having a secondary fuel supply unit positioned therein; An air injecting portion disposed to surround the fuel supply portion and having a first enlarged portion whose diameter is enlarged in a part of the combustion furnace side and a first reduced portion whose diameter is reduced from the first enlarged portion; A combustion gas suction unit having a first suction port opened toward the combustion furnace side and a second suction port located inside the combustion furnace at an outer peripheral surface; And a recirculation inducing unit disposed between the air injecting unit and the combustion gas sucking unit to communicate with the combustion gas sucking unit.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to an ultra-low NOx burner through internal recirculation of combustion gas and multi-stage fuel operation,

The present invention relates to a combustion apparatus, and more particularly, to a low-NOx combustion apparatus for efficiently reducing the amount of nitrogen oxides contained in a combustion gas by effectively recirculating a combustion gas produced by combustion of a fuel multi- .

At present, the main energy source of mankind is hydrocarbon fossil fuel. However, environmental pollution caused by combustion products of fossil fuels is seriously raised. In addition to nitrogen oxides (NOx) and carbon dioxide (CO2), the main sources of environmental pollution include carbon monoxide (CO) and soot generated by incomplete combustion of fuel (10). In conventional combustors using fossil fuels, it is inevitable to produce nitrogen oxides (NOx) having chemical formulas of NO and NO2 by chemical reaction at the time of combustion. The low NOx combustion technology for suppressing the generation of NOx has been developed to improve the structure of the combustor such as the mixture form of the fuel and the air and the air-fuel ratio. Nitrogen oxides generated in the combustion process react with other oxygen in the atmosphere and cause environmental problems such as smog and atmospheric ozone increase. In particular, emissions from these combustion processes are harming the environment and human health, and countries are tightening regulations on an increasingly stringent level.

The types of nitrogen oxides can be classified into thermal NOx, rapid NOx, and fuel NOx depending on the cause. The 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 generated at the initial stage of combustion in the combustion of hydrocarbon-based fuels. The fuel nitrogen oxides react with the nitrogen components contained in the fuel Lt; / RTI > Even in the countermeasures against such nitrogen oxides, it is effective to control matters related to thermal NOx and PromptNOx since gaseous fuels such as natural gas do not contain nitrogen components in the fuel.

Nitrogen oxides cause photochemical smog and acid rain and are known to have serious effects on flora and fauna. For a long time many researchers have studied various ways to reduce NOx. As a result of this, low NOx methods currently being tried include exhaust gas recirculation, water or steam injection, multi-stage combustion of air and fuel, selective non-catalytic reduction (SNCR), selective catalytic reduction (SCR) catalytic reduction). Recently, advanced countries are attempting to recycle NOx in the afterburning region, and it is known that NOx reduction efficiency and economic efficiency are high.

 However, existing technologies require a number of additional devices as elements for exhaust gas recirculation, and thus, there is a problem of economical efficiency and space securing.

As a combustor for applying a combustion gas recirculation by providing a fluid dynamic structure for recirculating fuel and combustion gas flowing in a combustion device without depending on such an additional device, there is a combustor disclosed in Korean Patent No. 1512352 proposed by the present applicant There is a low nitrogen oxide burner. However, such a combustor assumes a combustion system with a large combustion furnace, which limits the miniaturization of the apparatus.

KR 10-1512352 B1

SUMMARY OF THE INVENTION It is an object of the present invention to provide a method and apparatus for effectively controlling the flow rate of a fuel and an air mixture supplied into a combustion furnace and the flow rate of a combustion gas generated during combustion, And an object of the present invention is to provide an ultra low nitrogen oxide combustion device capable of reduction and miniaturization.

In order to attain the above object, the present invention provides a combustion apparatus including a combustor positioned to penetrate a predetermined distance into a combustion furnace, wherein the combustor includes a primary fuel supply unit located inside the combustion furnace, A fuel supply unit including a secondary fuel supply unit located on the combustion furnace side of the fuel supply unit; An air injecting portion disposed to surround the fuel supply portion and having a first enlarged portion whose diameter is enlarged in a part of the combustion furnace side and a first reduced portion whose diameter is reduced from the first enlarged portion; A combustion gas suction unit having a first suction port opened toward the combustion furnace side and a second suction port located inside the combustion furnace at an outer peripheral surface; And a recirculation inducing unit disposed between the air injecting unit and the combustion gas sucking unit to communicate with the combustion gas sucking unit.

The first intake port and the second intake port may distribute the combustion gas generated in the combustion furnace to be introduced into the combustion gas intake unit.

The air supplied to the air injecting unit is passed through the enlarging unit and the reducing unit at a faster speed than when supplied, and the fuel supplied to the primary fuel supplying unit is mixed with the air having the high speed to be supplied to the combustion furnace .

Preferably, the recirculation inducing portion includes a second reducing portion having a smaller width toward the combustion furnace at a side in communication with the combustion gas sucking portion, and a second enlarging portion having a gradually increasing width from the second reducing portion.

And the width of the second narrowing portion is narrowed by the first enlarging portion.

Preferably, the recirculation inducing portion includes a plurality of induction sleeves spaced apart from each other by a predetermined distance on a side in communication with the combustion gas suction portion, and the predetermined interval is gradually narrowed toward the recirculating induction portion side.

The combustor may further include a replenishing plate disposed at one end of the air injection port side of the combustion furnace.

The diameter of the recirculation inducing portion is A, the diameter of the first enlarging portion is A ', the length of the primary fuel injecting portion is B, the total length of the first reducing portion and the first enlarging portion is B' (A, A ', A', A ', A', C ', C', C ', C', and D respectively denote the length of the combustion chamber, the length of the first reduced portion, the diameter of the combustor, the length of penetration of the combustor into the furnace, , B, B ', C, C', D, and L) are determined by a predetermined formula.

The ultra low NOx combustion apparatus according to the present invention has a problem that the performance of a low NOx combustion apparatus is significantly reduced when a conventional low NOx combustion apparatus is applied to a combustion system having a small combustion mode, By applying the suppression combustion technology such as fuel multi-stage combustion technology and combustion gas recirculation combustion technology, it is possible to maintain the flame shape suitable for the small type combustion chamber by forming the narrow type flame, and by simultaneously applying the combustion gas recirculation technology, And an additional recirculating gas intake structure on the side of the combustor for optimization of the combustion gas recirculation is provided, thereby leading to an efficient recirculation flow structure.

1 schematically shows a low NOx combustion apparatus according to an embodiment of the present invention.
FIG. 2 and FIG. 3 are schematic views of a low nitrogen oxide combustion apparatus according to an embodiment of the present invention, and show the dimensions of the respective constitutions.
Figure 4 schematically illustrates the operation of a low NOx combustion apparatus in accordance with an embodiment of the present invention.
5 is a graph comparing the nitrogen oxide concentration in the combustion gas with the conventional combustion apparatus by the low nitrogen oxide combustion apparatus according to the embodiment of the present invention.

These and other objects, features and other advantages of the present invention will become more apparent by describing in detail preferred embodiments of the present invention with reference to the accompanying drawings. In this process, the thicknesses of the lines and the sizes of the components shown in the drawings may be exaggerated for clarity and convenience of explanation. In addition, the terms described below are defined in consideration of the functions of the present invention, which may vary depending on the intention or custom of the user, the operator. Therefore, the definitions of these terms should be described based on the contents throughout this specification.

In addition, the described embodiments are provided for illustrative purposes and do not limit the technical scope of the present invention.

Each component constituting the low nitrogen oxide combustion apparatus of the present invention can be used integrally or individually as needed. In addition, some components may be omitted depending on the usage pattern.

Hereinafter, a configuration of a low NOx combustion apparatus according to an embodiment of the present invention will be described in detail with reference to FIGS. 1 to 4 attached hereto.

As shown in FIG. 1, the low NOx combustion apparatus according to an embodiment of the present invention can be roughly composed of a combustion furnace 10 and a combustor (not shown).

The combustion furnace 10 has a hollow shape in which a space for combustion can be provided. The tip end of the combustor 10 penetrates into the space of the furnace 10 at a predetermined interval.

The combustor may include a fuel supply unit 100, an air injection unit 200, and a recirculation induction unit 300.

The fuel supply unit 100 includes a first fuel injection unit 110 located at one side of the combustion furnace 10 and a second fuel injection unit 110 located at one side of the combustion furnace 10, And a secondary fuel injection unit 120.

The fuel supplied from the other side (lower side as viewed in FIG. 1) of the fuel supply part 100 through the supply hole (not shown) formed in the outer peripheral surface of the primary fuel injection part 110 is injected into the primary fuel injection part 110 And it is preferable that the diameter is gradually widened toward the combustion furnace 10 side in order to inject fuel smoothly.

The secondary fuel injecting unit 120 injects the fuel supplied from the fuel supplying unit 100 into the combustion furnace 10 through a supply hole (not shown) drilled on the outer peripheral surface of the secondary fuel injecting unit 120.

The fuel thus supplied is supplied into the combustion furnace 10 through the first and second fuel injectors 120 in multiple stages.

The air injecting unit 200 is disposed in a form surrounding the fuel supplying unit 100 at a predetermined interval from the fuel supplying unit 100 so that air supplied from one side (lower side in FIG. 1) is mixed with the primary and secondary fuel And is supplied to the inside of the combustion furnace 10, where air is supplied, but it is also possible to supply an oxidizing agent or the like for generating combustion.

The air injector 200 is provided with a first enlarged portion (hereinafter referred to as a first enlarged portion) 100 located to surround the primary fuel supply portion 100 and the secondary fuel supply portion 100 on the side of the combustion furnace 10, 210 and a first shrinking portion 220.

The first enlarged portion 210 forms a shape in which the diameter of the first enlarged portion 210 gradually widens from the air supply side toward the combustion furnace 10 side and the first reduced portion 220 passes through the first enlarged portion 210, So that the diameter thereof is gradually reduced towards the furnace 10 side.

That is, a part of the air injection portion 200 on the side of the combustion furnace 10 has a shape in which the diameter is enlarged and narrowed. Therefore, the air supplied to the combustion furnace 10 is mixed with the fuel at a high flow rate relative to the flow rate when the air is supplied through the first enlargement 210 and the first reduction 220, (Not shown).

The combustion gas sucking unit 400 is located in a space between the air injecting unit 200 and the air injecting unit 200 at a predetermined interval and is disposed between the combustion gas sucking unit 400 and the air injecting unit 200 The interval becomes the configuration of the recirculation inducing unit 300 to be described later.

The combustion gas sucking unit 400 includes a first suction port 410 opened to the side of the combustion furnace 10 and a second suction port 420 positioned on the outer circumferential surface of the combustion gas sucking unit 400, do.

Due to the structure of the first and second intake ports 420, the combustion gas generated during the combustion in the combustion furnace 10 is distributed to the first and second intake ports 420 and flows into the combustion gas intake unit 400 .

The recirculating induction unit 300 is positioned between the air injecting unit 200 and the combustion gas intake unit 400 so as to surround the air injecting unit 200. One side of the recirculating induction unit 300 The combustion gas introduced into the combustion gas intake part 400 is recycled into the combustion furnace 10 by communicating with the combustion gas part 400. The induction sleeves 331 and 332 are connected to the combustion gas intake part 400 and the recirculation induction part 300 in order to allow the combustion gas introduced into the combustion gas intake part 400 to flow smoothly into the recirculation induction part 300. [ The distance between the induction sleeves 331 and 332 provided on the side of the recirculation inducing unit 300 is set to the center side of the recirculating induction unit 300, And may be in a form gradually narrowing along the inflow direction of the gas.

The recirculation inducing unit 300 includes a second reducing unit 310 and a second reducing unit 310. The second reducing unit 310 has a width narrower than the second reducing unit 310, (320).

The diameter of the first enlarged portion 210 of the air injection portion 200 in contact with the recirculation inducing portion 300 may be enlarged so that the width of the first enlarged portion 210 may be gradually narrowed. Therefore, it is possible to form the second scaled portion 310 without introducing a separate scaled structure.

The second enlarging unit 320 is formed by positioning the enlarging sleeve 333 having an inclined structure such that the diameter of the recycling inducing unit 300 is enlarged past the second reducing unit 310.

 As a result, the air introduced into the combustion gas suction unit 400 flows into the recirculation induction unit 300 through the induction sleeve, and the flow rate thereof increases as the gas passes through the second reducing unit 310 and the second enlarging unit 320 Therefore, the recirculation efficiency of the combustion gas can be improved by recirculating the combustion gas at a high speed.

Specifically, the difference between the low-NOx combustion apparatus according to the present invention and the conventional combustion apparatus is as follows.

First, in order to optimize the combustion gas recirculation structure, an additional intake port on the side of the burner in addition to the conventional combustion gas recirculation inlet can be provided to optimize the recirculation flow structure suitable for the small furnace 10.

 The configuration of the air injection unit 200 is configured to expand and contract at the exit position of the air. The numerical values of the respective constitutions of the combustion apparatus optimized for this structure and the small combustion furnace 10 are shown in Figs. 2 to 3 It can be designed as shown in Fig.

2 to 3, the diameter of the recirculation inducing portion 300 is A, the diameter of the first enlarging portion 210 is A ', the length of the primary fuel injecting portion 110 is B, A total length of the first shrinking portion 220 and the first shrinking portion 220 is B ', a length of the first shrinking portion 220 is C, a diameter of the first shrinking portion 220 is C' When the diameter of the combustor is D, the interval of penetration of the combustor into the combustion furnace 10 is L, and the expansion coefficient is X, the dimensions of each constitution of the low NOx combustion apparatus according to the embodiment of the present invention are as follows: Can be defined as follows.

Specifically, X shown in the above equation should be adjusted according to the capacity of the combustor as an expansion coefficient. The smaller the burner capacity, the closer to 0.8, and the larger the burner capacity, the closer it is to 1.2.

Therefore, the diameter (expanded dimension, A ') of the first enlarged portion 210 is expressed by the product of the dimension A' of the recirculation inducing portion 300 and the expansion coefficient X.

 The length B 'of the first enlarged portion 210 and the first reduced portion 220 may be twice the length B of the first fuel injection portion 110.

The formula for the internal penetration length L of the combustor 10 of the combustion furnace 10 is related to the diameter of the combustor and is closer to 2.0 D as the diameter A 'of the first enlarged portion 210 is larger.

Hereinafter, the operation of the low NOx combustion apparatus according to the present invention will be described with reference to FIG.

First, the fuel supplied through the fuel supply unit 100 is injected in multiple stages through the primary fuel injection unit 110 and the secondary fuel injection unit.

The air supplied through the air supply unit flows through the first enlargement unit 210 and the first reduction unit 220 and is mixed with the air with the increased flow rate and the supplied fuel, And combustion is performed. At this time, since the fuel and air are mixed and supplied to the inside of the combustion furnace 10 at a high speed, the flame may become unstable. In order to stabilize the flame, the combustion chamber 10 of the air injection unit 200 (Not shown) may be provided at the tip thereof. In the conventional combustion apparatus, a high temperature region (C1, fuel rich region) and a relatively low temperature region (C2, fuel lean region) are generated during combustion. By mixing fuel and air at high speed as described above, The combustion can be efficiently performed by eliminating the high-temperature region C1.

In the combustion apparatus using the hydrodynamic structure according to the high-speed fuel and air supply, it is important to control the flow rate of the fuel and the air as described above. However, And it is also important to effectively control the recirculation thereof. As described above, the combustion gas generated by the combustion flows to the upper portion of the combustion furnace 10 and then flows downward to the lower portion. The combustion gas flowing at high speed flows through the first inlet 410 and the second inlet 420, And is then introduced into the combustion gas suction unit 400. When only the suction port opened toward the combustion furnace 10 side is located as in the conventional case, some of the descending combustion gas is not smoothly flowed in the vicinity of the inner periphery of the lower portion of the combustion furnace 10, The low NOx combustion apparatus according to the present invention includes the second intake port 420 for sucking the combustion gas, thereby enhancing the efficiency of intake of the combustion gas.

The combustion gas introduced into the combustion gas intake unit 400 through the first and second intake ports flows into the recirculation induction unit 300 and is recirculated. At this time, the combustion gas is sucked into the combustion gas intake unit 400 and the recirculation induction unit 300 The second narrowing portion 310 and the second enlarging portion 320, and is recirculated to the inside of the combustion furnace 10 with an increased flow rate.

As shown in FIG. 5, it was confirmed that the concentration of nitrogen oxide contained in the combustion gas was greatly reduced through the combustion of the combustion gas through the high-speed fuel supply and the recirculation of the combustion gas.

As described above, according to the ultra low nitrogen oxide combustion apparatus of the present invention, in the conventional low nitrogen oxide combustion apparatus, the performance of the low nitrogen oxide combustion apparatus is significantly lowered when the combustion system is applied to a small combustion furnace type By adopting the suppression combustion technology such as air multi-stage combustion technology, fuel multi-stage combustion technology, and combustion gas recirculation combustion technology, it is possible to maintain the flame shape suitable for small type combustion chamber by forming narrow type flame and to simultaneously apply the combustion gas recirculation technology This allows effective reduction of nitrogen oxides and an efficient recirculation flow structure by providing an additional combustion gas suction structure on the side of the combustor for combustion gas recycle optimization.

Although the preferred embodiments of the present invention have been described, the present invention is not limited to the specific embodiments described above. It will be apparent to those skilled in the art that numerous modifications and variations can be made in the present invention without departing from the spirit or scope of the appended claims. And equivalents should also be considered to be within the scope of the present invention.

10: Combustion furnace
100: fuel supply unit
110: Primary fuel injection part
120: Secondary fuel injection part
200:
210: first magnifying section
220: second magnifying unit
300: recirculation induction part
310:
320:
400: Combustion gas suction part
410: first inlet
420: second inlet

Claims (8)

A combustor comprising a combustor in which a part of a tip end penetrates a predetermined length into a combustion furnace (10)
The combustor
(100) having a primary fuel injection portion (110) located inside the combustion furnace (10) and a secondary fuel injection portion (120) located on the combustion path side of the primary fuel injection portion );
A first enlarged portion 210 disposed to surround the fuel supply portion 100 and having a diameter enlarged by a part of the combustion furnace 10 side portion and a first enlarged portion 210 having a diameter reduced from the first enlarged portion 210, (200) having an air injection port (220);
(420) having a first suction port (410) whose tip is opened toward the combustion furnace (10) side and a part of an outer circumferential surface penetrating a predetermined length into the combustion furnace (10) (400); And
And a recirculation inducing unit 300 positioned between the air injecting unit 200 and the combustion gas intake unit 400 to communicate with the combustion gas intake unit 400,
A combustion gas generated in the combustion furnace 10 and flowing to the combustor side flows into the first intake port 410 and the second intake port 420 and flows through the recirculation induction unit 300 to the combustion furnace 10 ) ≪ / RTI >
Low nitrogen oxide combustion apparatus.
delete The method according to claim 1,
The air supplied to the air injecting unit 200 passes through the first enlarging unit 210 and the first reducing unit 220 in order,
Wherein the fuel supplied to the primary fuel supply unit (100) is mixed with the air having the high speed and supplied to the combustion furnace (10)
Low nitrogen oxide combustion apparatus.
The method according to claim 1,
The recirculation inducing unit 300 may include:
A second reducing part 310 which is narrowed in width from the combustion gas suction part 400 side toward the combustion furnace 10 side and a second enlarging part 310 which is gradually wider from the second reducing part 310 320,
Low nitrogen oxide combustion apparatus.
5. The method of claim 4,
The second narrowing portion 310 is formed by the first enlarging portion 210,
Low nitrogen oxide combustion apparatus.
The method according to claim 1,
The recirculation inducing unit 300 may include:
And a plurality of induction sleeves (331, 332) spaced apart from each other by a predetermined distance on a side communicating with the combustion gas suction unit (400), the predetermined interval being gradually narrower toward the recirculation induction unit (300)
Low nitrogen oxide combustion apparatus.
The method according to claim 1,
The combustor
(10) side of the air injection part,
Low nitrogen oxide combustion apparatus.
The method according to claim 1,
The diameter of the recirculation inducing portion 300 is A, the diameter of the first enlarging portion 210 is A ', the length of the primary fuel injecting portion 110 is B, the length of the first reducing portion 220, The length of the first enlarged portion 210 is denoted by B ', the length of the first reduced portion 220 is denoted by C, the diameter of the first reduced portion 220 is denoted by C', the diameter of the combustor is denoted by D, (A, A ', B, B', C, C ', D, and L) is determined by the following equation when the penetration interval to the combustion furnace 10 is L and the expansion coefficient is X ,
Low nitrogen oxide combustion apparatus.

Here, X is 0.8? X? 1.2

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