KR101528807B1 - Super-low NOx eission combustion apparatus using coanda effect - Google Patents

Abstract

The present invention relates to a super-low NOx combustion apparatus using a Coanda effect, which comprises: a combustion chamber, a housing, a Coanda nozzle, an air supplying part, and a core. The combustion chamber has a plurality of inflow holes passing through an outer circumferential surface thereof, and allows a target combustion substance to be burned therein. The housing is spaced from the outer circumferential surface of the combustion chamber at a predetermined interval, and has a gas flow passage formed along the outer circumferential surface of the combustion chamber to allow combustion gas at a high temperature to flow. The Coanda nozzle is installed in each inflow hole and has a flow passage which induces the combustion gas at a high temperature to flow inside due to an air injected inside and flows again into the combustion chamber, and a curved part formed on the flow passage while having a diameter become narrower. The air supplying part injecting air inside the Coanda nozzle, and the core is installed inside the Coanda nozzle to allow the inner space of the Coanda nozzle to become narrower. Accordingly, the super-low NOx combustion apparatus prevents a flow separation phenomenon whereby air flowing along the inner circumferential surface of the Coanda nozzle flows separately; thereby preventing a reduction in suction force generated inside the Coanda nozzle.

Description

[0001] The present invention relates to a super-low NOx emission combustion apparatus using coanda effect,

The present invention relates to an ultra low NOx combustion apparatus using a Coanda effect in which air approaching a wall flows on a surface thereof.

1 is a conceptual diagram of ultra low NOx MILD combustion.

As shown in FIG. 1, when a conventional burner using air as an oxidizer measures a temperature along a central axis of the burner, there is a high temperature region of about 2000K as shown in the figure as a heat spot . Nitrogen oxides (NOx) are generated very rapidly (milli second range) in this high temperature zone, so lowering this high temperature range is a very important way to realize low NOx combustion.

In recent years, a method of preheating the air by recovering the heat of the combustion gas by using a heat exchanger in order to increase the energy efficiency has been used. In this case, the peak temperature of the flame is further increased and the production rate of NOx is further increased do. Therefore, there is a need for a technique for preventing the maximum temperature of the flame zone from increasing when the air is preheated.

2 is a graph showing the oxygen concentration and the temperature distribution at the maximum temperature on the burner center line.

As shown in FIG. 2, when the concentration of oxygen is as high as 7% in a conventional burner, the maximum temperature of the flame increases when the air is preheated to 1200 K and the air is preheated to 1600 K. And the generation of NOx is greatly increased.

However, if the concentration of oxygen is lowered, even if the air is preheated to 1600 K, the maximum temperature of the flame is greatly lowered, while the temperature of the downstream portion where the temperature is lower is increased, and the temperature tends to be generally leveled. Using this method, extremely low NOx combustion can be realized.

In order to lower the concentration of oxygen, a method of returning the combustion gas generated by combustion of the fuel and mixing it with the air flow is used.

3 is a graph showing an appearance area of ultra low NOx MILD combustion.

As shown in FIG. 3, when the cooled combustion gas is recirculated, the region where the flame is stabilized is greatly narrowed, and if the amount of the recirculated combustion gas is increased, the flame becomes unstable or turned off. Thus, if the flue gas is recirculated while maintaining the high temperature condition, a very stable flame region indicated by MILD mode appears in FIG.

In other words, a combustion method that keeps the flame stable by keeping the high temperature while lowering the oxygen concentration by mixing and diluting the combustion gas while heating the combustion air to above the ignition temperature of the fuel is called the Moderate and Intense Low oxygen dilution.

This MILD combustion method uses a heat exchanger to recirculate the combustion gas and increase the temperature of the air. However, in order to raise the temperature of the air above the ignition temperature of the fuel, generally above 1000 ° C, it is impossible to use a heat exchanger as a general heat exchanger.

A regenerative regenerative heat exchanger is a method for heating a high temperature combustion gas to pass through a heat accumulating material of a ceramic type and heating it to a high temperature and then flowing air toward the heat regenerating material again to obtain a high temperature, (4-way switching valve) that can withstand high temperatures. (Since the method of heating the air at a high temperature is used, the apparatus becomes complicated and the price becomes high.

In order to solve this problem, the applicant of the present invention has proposed a high-temperature FGR ultra low NOx combustion apparatus using the Coanda effect of Korean Patent No. 1320406, comprising: a combustion chamber having an inlet hole formed on an outer circumferential surface thereof; A housing installed on the outer side of the combustion chamber and in which a high temperature combustion gas burnt in the combustion chamber flows; A coanda nozzle disposed in the inflow hole and having a mixing hole formed between the inflow hole and the auxiliary hole; And an air supply unit that generates a suction force in the Coanda nozzle and injects air into the inside of the Coanda nozzle so as to suck the mixed air in which the high temperature combustion gas and the outside air are mixed into the combustion chamber and discharge the mixed air to the outside A high-temperature FGR ultra low NOx combustion device using the Coanda effect is proposed.

In this case, according to the prior art, when the air supply part is constituted by a small tube (diameter is 24 mm or less), the air supply part is sucked into the inside of the housing by the suction force generated inside the coiled nozzle, The maximum amount of mixed air to be discharged is 3.8 times.

 However, in the prior art, when the air supply portion is constituted by a large tube (diameter of 100 mm or more), the air supply portion is sucked into the interior of the housing by the suction force generated inside the Coanda nozzle compared with the air amount injected by the Coanda nozzle, The amount of mixed air discharged is reduced to a maximum of two times.

More specifically, the air injected from the air nozzle to the air nozzle is adhered to the inner circumferential surface of the air nozzle. When air is supplied from the small nozzle, the air flows smoothly along the inner surface of the air nozzle However, when the air supply part is constituted by a large nozzle, a flow separation phenomenon that flows away from the inner circumferential surface of the coanda nozzle occurs, and the suction force generated inside the coanda nozzle is reduced.

Therefore, it is necessary to develop an ultra low NOx combustion apparatus using various Coanda effects to solve the above-mentioned problems.

Korean Patent No. 1320406 (Oct. 15, 2013)

SUMMARY OF THE INVENTION The present invention has been conceived to solve the problems described above, and it is an object of the present invention to prevent a flow separation phenomenon from occurring due to air flowing along the inner circumferential surface of a coanda nozzle, The present invention is to provide an extremely low NOx combustion apparatus using the Coanda effect.

The ultra low NOx combustion apparatus using the Coanda effect according to the present invention includes a combustion chamber in which a plurality of inlet holes are formed in the outer circumferential surface, and a combustion target material is burnt therein; A housing disposed at a predetermined distance from an outer circumferential surface of the combustion chamber and forming a gas flow passage for flowing a hot combustion gas between the outer circumferential surfaces of the combustion chamber; A flow path provided in the inflow hole and causing the hot combustion gas to flow inward by the air injected into the inflow hole and re-flowing into the combustion chamber; and a curved portion having a narrowed diameter in the flow path, An air supply unit for injecting air into the Coanda nozzle; And a core installed inside the Coanda nozzle so that the inner space of the Coanda nozzle is narrowed.

The core is characterized in that a first taper is formed in the Coanda nozzle where a diameter of one end located at a position where the high temperature combustion gas is attracted is gradually narrowed toward the opposite direction in which the high temperature combustion gas is attracted.

The core is characterized in that a second taper is formed in which the diameter of the other end of the core is gradually widened toward the direction in which the hot combustion gas is introduced.

The ultra low NOx combustion apparatus using the Coanda effect further includes a wastewater pipe communicating the gas flow passage with a discharge port of the combustion chamber, wherein the Coanda nozzle is installed inside the wastewater pipe.

In addition, a plurality of Coanda nozzles are provided in the inside of the right tube, and a mixed gas in which air and a high temperature combustion gas are mixed is supplied to the combustion chamber after air and hot combustion gas are mixed in the right tube .

Accordingly, the ultra low NOx combustion apparatus using the Coanda effect according to the present invention can prevent the flow separation phenomenon caused by the air flowing along the inner circumferential surface of the Coanda nozzle, thereby reducing the suction force generated inside the Coanda nozzle Can be prevented.

1 is a conceptual diagram of ultra low NOx MILD combustion
2 is a graph showing the oxygen concentration and the temperature distribution at the maximum temperature on the burner center line
3 is a graph showing the appearance area of ultra-low NOx MILD combustion
4 is a front view showing an ultra low NOx combustion apparatus using the Coanda effect according to the present invention.
5 is a schematic view showing an ultra low NOx combustion apparatus using the Coanda effect according to the present invention.
6 is a schematic view showing a first embodiment of the ultra low NOx combustion apparatus using the Coanda effect according to the present invention.
7 is a schematic view showing a second embodiment of the ultra low NOx combustion apparatus using the Coanda effect according to the present invention.
8 is a schematic view showing a third embodiment of the ultra low NOx combustion apparatus using the Coanda effect according to the present invention.

Hereinafter, the technical idea of the present invention will be described more specifically with reference to the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS The accompanying drawings, which are included to provide a further understanding of the technical concept of the present invention, are incorporated in and constitute a part of the specification, and are not intended to limit the scope of the present invention.

The present invention relates to an ultra low NOx combustion apparatus using a Coanda effect in which air approaching a wall flows on a surface thereof.

At this time, the ultra-low NOx combustion lowers the maximum temperature of the flame zone, thereby generalizing the flame temperature and the oxygen concentration as a whole.

To this end, the present invention preheats the combustion air by mixing the high temperature combustion gas with air for combustion (air in the atmosphere and air for generating a Coanda effect), and mixes the combustion air and the combustion gas to lower the oxygen concentration .

FIG. 4 is a schematic view showing an ultra low NOx combustion apparatus using the Coanda effect according to the present invention, and FIG. 5 is a schematic diagram showing an ultra low NOx combustion apparatus using the Coanda effect according to the present invention.

4 to 5, an ultra low NOx combustion apparatus using the Coanda effect according to the present invention includes a combustion chamber 10, a housing 20, a Coanda nozzle 40, an air supply unit 50, a core (not shown) 70).

The combustion chamber 10 is formed with a plurality of inlet holes 11 spaced apart from each other in the longitudinal direction on the outer circumferential surface thereof, a fuel supply unit 12 into which a combustion target material is injected is formed, (13).

The diameter of the inlet holes 11 of the combustion chamber 10 may be different according to various embodiments of the user and the diameter of the plurality of inlet holes 11 may be varied in the longitudinal direction of the combustion chamber 10 The inlet hole 11 may be formed in the tangential direction of the inner wall of the combustion chamber 10, or may be formed at a predetermined angle with the inner wall of the combustion chamber 10, .

When the same amount of air is supplied throughout the lengthwise direction of the combustion chamber 10, combustion can occur from one side of the combustion chamber 10 at a time, The combustion speed of the combustion chamber 10 can be controlled by increasing the size of the inflow hole 11 toward the direction of the combustion chamber 10 or adjusting the air supply amount flowing into the inflow hole 11. [

The housing 20 is spaced apart from the outer circumferential surface of the combustion chamber 10 and has a gas flow passage 21 for flowing a high temperature combustion gas between the outer circumferential surface of the combustion chamber 10 and the inner circumferential surface of the housing 20, .

The housing 20 is provided at the other side of the housing 20 with an observation window 62 for allowing the inside of the combustion chamber 10 to be seen from the outside and a discharge window for discharging the combustion residues Ash and C generated in the combustion chamber 10 A discharge port 60 in which a line 61 is formed may be further provided so that the inside of the discharge port 60 is in communication with the combustion chamber 10 and the housing 20.

The high temperature combustion gas generated in the combustion chamber 10 flows to the gas flow passage 21 from the other side of the combustion chamber 10 through the discharge portion 60 and is then communicated with the gas flow passage 21 And is discharged to the outside through the stack (22) of the installed housing (20).

The Coanda nozzle (40) is installed in the inlet hole (11), and a flow path (41) formed in the longitudinal direction is formed therein.

The flow path 41 serves to generate a suction force due to the Coanda effect so that the high temperature combustion gas (exhaust gas) discharged from the combustion chamber 10 is drawn.

The flow path 41 is formed in such a shape that its diameter gradually increases in a direction in which the combustion gas (exhaust gas) is sucked.

More specifically, the flow path 41 has a shape in which the diameter becomes narrower toward the direction in which the combustion gas (exhaust gas) is sucked, and gradually becomes gradually sloped and gradually increases in diameter. In this flow path 41, a portion where the diameter is narrowest is formed as a curved portion 42.

One end of the air supply unit 50 communicates with the flow path 41 of the Coanda nozzle 40 and supplies air to the flow path 41 of the Coanda nozzle 40.

At this time, one end of the air supply part 50 communicates with the curved part 42.

In other words, when the air supply unit 50 injects air, the air flows in one direction in close contact with the gentle slope flow path 41, and a suction force due to the coanda effect is generated in the flow path 41 .

As a result, the hot exhaust gas, which is burned and discharged from the combustion chamber 10, flows into the gas flow passage 21, and the hot exhaust gas flowing into the gas flow passage 21 flows into each of the inlet holes 11 Is sucked into each of the coanda nozzles (40) in each of the inflow holes (11) by the air injected and supplied toward the combustion chamber (10) in the coaxial nozzle (40) And is re-introduced into the combustion chamber 10 in the form of a mixed gas.

That is, according to the present invention, the fuel is supplied into the combustion chamber 10 preheated above the ignition temperature of the fuel, and the combustion gas of the high temperature is recycled and mixed in the air (oxidizing agent) The MILD combustion is achieved so that the high temperature portion concentrated in the flame zone does not occur without being scattered at the uniform temperature throughout the entire combustion chamber 10, thereby minimizing the generation of CO and NOx. At the same time, The amount of high temperature exhaust gas sufficient for mixing can be sucked into the combustion chamber 10 through the configuration of the coanda nozzle 40 and the air supply portion 50, ) And the entire size of the combustion apparatus can be remarkably reduced.

The core 70 is configured such that the air guided to the flow path 41 of the Coanda nozzle 40 is separated from the flow path 41 of the Coanda nozzle 40 and flows into the inside of the Coanda nozzle 40 (40) so that the internal space of the Coanda nozzle (40) is narrowed in order to prevent the flowing flow separation phenomenon.

At this time, the core 70 is fixed to the core 70 through a plurality of supports (not shown) installed between the flow path 41 of the core nozzle 40 and the outer peripheral surface of the core 70, , But the present invention is not limited thereto.

In addition, the core 70 is preferably installed on the inner central axis of the Coanda nozzle 40.

Accordingly, the ultra low NOx combustion apparatus using the Coanda effect according to the present invention prevents the flow of air flowing along the inner circumferential surface of the Coanda nozzle 40, that is, the flow path 41, It is possible to prevent the suction force generated inside the Coanda nozzle 40 from being reduced.

In particular, even when the coanda nozzle 40 and the air supply unit 50 are both made of a large tube (diameter of 100 mm or more), the ultra-low NOx combustion apparatus using the Coanda effect, By narrowing the internal space of the Coanda nozzle 40, it is possible to prevent the flow of the air flowing along the inner circumferential surface of the Coanda nozzle 40, that is, the flow passage 41, from flowing away.

On the other hand, the core 70 has a first taper 71 whose diameter gradually decreases toward the opposite direction in which the high temperature combustion gas is attracted, where the diameter of the one end opposite to where the high temperature combustion gas is drawn from the Coanda nozzle 40, Can be formed.

The first taper 70 serves to guide the high temperature combustion gas and air flowing into the Coanda nozzle 40 to the flow path 41 of the Coanda nozzle 40.

In addition, the core 71 may further include a second taper 72 whose diameter at the other end of the core 70 is gradually widened toward the direction in which the hot combustion gas is introduced.

The second taper 72 further narrows the flow path 41 to further prevent all the air flowing along the surface of the flow path 41 from falling off and flowing.

Hereinafter, various embodiments of the ultra low NOx combustion apparatus using the Coanda effect according to the present invention will be described.

≪ Example 1 >

6 is a schematic view showing a first embodiment of an ultra low NOx combustion apparatus using the Coanda effect according to the present invention.

6, in the first embodiment of the ultra-low NOx combustion apparatus using the Coanda effect according to the present invention, the stack 22 is formed at the upper end of the discharge portion 60 of the combustion chamber 10, (22) and the gas flow passage (21) through the through hole (30).

That is, the discharge portion 60 communicates with the combustion chamber 10, and the gas flow passage 21 (not shown) which is not communicated with the gas flow passage 21 and is formed between the housing 20 and the combustion chamber 10 Is further configured to communicate with the discharge portion 60 (more specifically, the stack 22 of the discharge portion 60) of the combustion chamber 10. [

The coanda nozzle 40 is installed inside the right tube 30 (more specifically, at one side of the right tube 30 (the portion where the right tube 30 and the collar 22 are connected)).

At this time, the high-temperature combustion gas burned and discharged in the combustion chamber 10 is discharged to the outside through the discharge portion 60 and the stack 22, and during the discharge, the coanda nozzle 40 The hot exhaust gas discharged to the stack 22 is drawn into the right tube 30 by the supplied air.

Accordingly, in the first embodiment of the ultra-low NOx combustion apparatus using the Coanda effect according to the present invention, the air supplied from the air supply unit 50 is supplied to the combustion chamber 10 and simultaneously the high temperature combustion gas is mixed The mixed gas in the mixed state flows through the gas flow passage 21 and flows into the outer peripheral surface of the combustion chamber 10 through the inflow of the outer peripheral surface of the combustion chamber 10 And is supplied into the combustion chamber 10 through the hole 11.

At this time, the core 70 is rotated so that the air guided to the flow path 41 of the Coanda nozzle 40 is separated from the flow path 41 of the Coanda nozzle 40, So that the inner space of the Coanda nozzle 40 is narrowed to prevent a flow separation phenomenon flowing into the inside of the Coanda nozzle 40. [

≪ Example 2 >

7 is a schematic view showing a second embodiment of an ultra low NOx combustion apparatus using the Coanda effect according to the present invention.

7, the second embodiment of the ultra-low NOx combustion apparatus using the Coanda effect according to the present invention includes a combustion chamber 10 in which a fuel supply unit 12 is formed, a combustion chamber 10 disposed apart from the outer circumferential surface of the combustion chamber 10 And a discharge unit 60 communicating with the combustion chamber 10 and the housing 20 are provided.

At this time, a high-temperature exhaust gas attracted by the air flow is introduced into the combustion chamber (ex. The exhaust passage) by a plurality of Coanda nozzles 40 formed on the sidewall of the incinerator, Incinerator) to form MILD combustion.

More specifically, when a substance to be burned (or to be burned) is provided through the fuel supply unit 12 formed at one end of the housing 20, the provided burned substance is supplied to the combustion chamber 10 And is burned by a burner 13 or the like installed in the combustion chamber 10. [

Thereafter, the residue is discharged to the lower end of the discharge portion 60, and the high-temperature combustion gas generated while being burned in the combustion chamber 10 passes through the discharge portion 60 and the gas formed between the combustion chamber 10 and the housing 20 Flows into the flow passage (21).

At this time, the core 70 is rotated so that the air guided to the flow path 41 of the Coanda nozzle 40 is separated from the flow path 41 of the Coanda nozzle 40, So that the inner space of the Coanda nozzle 40 is narrowed to prevent a flow separation phenomenon flowing into the inside of the Coanda nozzle 40. [

≪ Example 3 >

8 is a schematic view showing a third embodiment of an ultra low NOx combustion apparatus using the Coanda effect according to the present invention.

8, the third embodiment of the ultra low NOx combustion apparatus using the Coanda effect according to the present invention is characterized in that the high temperature combustion gas generated in the combustion chamber 10 is supplied by the Coanda nozzle 40, The coanda nozzle 40 and the air supply unit 50 are disposed at one side of the gas flow passage 21 in the form of a burner by reusing the gas into the combustion chamber 10 and mixing the air with the air to burn the fuel.

The burner chamber 10 is opened at one end thereof and is spaced apart from the outer circumferential surface of the combustion chamber 10 so as to surround the combustion chamber 10, And a housing 20 for forming a gas flow passage 21 therebetween.

At this time, the fuel is supplied to the one side portion of the space between the combustion chamber 10 and the housing 20 through the fuel supply pipe, and the burner 13 is installed in the portion where the fuel is supplied. Thus, in the combustion chamber 10, the fuel supplied through the fuel supply unit 12, the air supplied through the gas flow passage 21 described above, the combustion flame through the burner 13, and the high- It will be discharged.

That is to say, of the gas flow passages 21 formed on the outer circumferential surface of the combustion chamber 10 and the housing 20, one or a plurality of Coanda nozzles 40 And an air supply unit 50 are provided.

Accordingly, when the high-temperature combustion gas is discharged together with the combustion flame in the combustion unit, when the air supply unit 50 supplies the air toward the fuel supply observation side within the Coanda nozzle 40, The exhaust gas is introduced into the gas flow passage 21 and the air and the hot exhaust gas are mixed in the gas flow passage 21 and supplied to the fuel supply portion 12 in the form of a mixed gas.

At this time, the core 70 is rotated so that the air guided to the flow path 41 of the Coanda nozzle 40 is separated from the flow path 41 of the Coanda nozzle 40, So that the inner space of the Coanda nozzle 40 is narrowed to prevent a flow separation phenomenon flowing into the inside of the Coanda nozzle 40. [

The air supply unit 50 may be provided with a separate air supply device (e.g., an air compression tank, an air pump or a blower, an air head 52, etc.) for supplying air.

It will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims.

10: combustion chamber 11: inlet hole
12: fuel supply unit 13: burner
20: housing 21: gas flow passage
22: chimney 23: ram pusher
30: Woo hall 40: Koanda Nozzle
41: flow path 42: bend section
50: air supply part 51: control valve
52: air head 60:
61: discharge line 62: observation window
70: core 71: first taper
72: second taper

Claims (5)

A combustion chamber in which a plurality of inlet holes perforated on an outer circumferential surface are formed, and a combustion target material is burnt therein;
A housing disposed at a predetermined distance from an outer circumferential surface of the combustion chamber and forming a gas flow passage for flowing a hot combustion gas between the outer circumferential surfaces of the combustion chamber;
A flow path provided in the inflow hole and causing the hot combustion gas to flow inward by the air injected into the inflow hole and re-flowing into the combustion chamber; and a curved portion having a narrowed diameter in the flow path,
An air supply unit for injecting air into the Coanda nozzle;
And a core disposed inside the Coanda nozzle to narrow the internal space of the Coanda nozzle.
2. The method of claim 1,
And a first taper which is gradually narrowed in a direction opposite to the direction in which the high temperature combustion gas is attracted is formed at the end of the Coanda nozzle where the high temperature combustion gas is attracted. Combustion device.
3. The device of claim 2,
And the other end of the core has a second taper that gradually widens toward a direction in which the hot combustion gas is introduced.
The ultra low NOx combustion apparatus according to claim 1, wherein the ultra low NOx combustion apparatus using the Coanda effect
And a wastewater pipe communicating the gas flow passage with the discharge portion of the combustion chamber,
Wherein the Coanda nozzle is installed inside the right tube.
5. The method of claim 4, wherein the Coanda nozzle
A plurality of tubes are installed inside the right tube,
Wherein a mixed gas in which air and a high temperature combustion gas are mixed is supplied to the combustion chamber after the air and the high temperature combustion gas are mixed in the inside of the right tube and the ultra low NOx combustion apparatus using the Coanda effect.

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