CN107690557B - Ultra-low NOx combustion device - Google Patents

Abstract

The invention relates to an ultra-low nitrogen oxide combustion device based on internal recirculation of combustion gas and fuel optimization, and provides an ultra-low nitrogen oxide combustion device, which comprises: a combustion furnace; a burner, one side of which is inserted into the combustion furnace, and the inserted side and the outer peripheral surface of which are separated from the inner surface of the combustion furnace by a predetermined interval; a main fuel injection body located at the center of the combustor; an auxiliary fuel injection body surrounding the main fuel injection body and having an end portion that is retracted from one side end portion of the burner toward the other side by a predetermined interval; a fuel recirculation port located near a position on an outer peripheral surface of the combustor where an end of the auxiliary fuel injection body is located; and a sensor for sensing a concentration of CO contained in the combustion gas generated in the combustion furnace.

Description

Ultra-low NOx combustion device

technical field

The present invention relates to an ultra-low nitrogen oxide combustion device based on internal recirculation of combustion gas, and more particularly, to an ultra-low nitrogen oxide combustion device, in which the combustion gas generated in the combustion chamber does not require additional devices. Passing from inside the combustion chamber, rather than by the external connecting passages of said combustion chamber, enables more efficient internal recirculation of combustion gases through optimal control of the structure and fuel distribution of the burner for more efficient combustion gas flow.

Background technique

The main source of energy for humans today is hydrocarbon fossil fuels. However, the environmental pollution caused by the combustion products of such fossil fuels is a serious problem. The main sources of environmental pollution are nitrogen oxides (NO _x ), carbon dioxide (CO ₂ ), and carbon monoxide (CO) and soot (soot) produced by incomplete combustion of fuel.

In conventional burners using fossil fuels, nitrogen oxides (NO _x ) having chemical formulae NO and NO ₂ are inevitably generated due to chemical reactions during combustion. The low _NOx combustion technology achieves the purpose of suppressing the formation of nitrogen oxides by improving the structure of the burner such as the mixing form of fuel and air and the air-fuel ratio. Nitrogen oxides produced during combustion react with other oxygen in the atmosphere, causing environmental problems such as smog and increased atmospheric ozone. In particular, the emission produced in this combustion process is harmful to the environment and human health, so countries are strengthening the control with increasingly strict standards.

The types of nitrogen oxides can be classified into thermal nitrogen oxides (Thermal NO _x ), rapid nitrogen oxides (Prompt NO _x ), and fuel nitrogen oxides (Fuel NO _x ) according to the reasons for their generation. Thermal nitrogen oxides are generated by the reaction of nitrogen and oxygen in the air at high temperatures above 1600 °C. Rapid nitrogen oxides are generated during the initial combustion of hydrocarbon fuels. Fuel nitrogen oxides are produced through the fuel. It is produced by the reaction of the contained nitrogen components. In terms of countermeasures against such nitrogen oxides, since gas fuels such as natural gas do not contain nitrogen components, there is a possibility that the control of matters related to thermal nitrogen oxides and rapid nitrogen oxides may be more effective.

Nitrogen oxides are the cause of photochemical smog and acid rain, and are known to have serious effects on animals and plants. For a long time, many researchers have studied various methods to reduce _NOx .

Therefore, the currently tried low _NOx methods include exhaust gas recirculation, water or steam injection, multi-stage combustion of air and fuel, selective non-catalytic reduction reaction (SNCR, selective non-catalytic reduction), selective catalytic reduction reaction (SNCR). ,selective catalytic reduction) and so on. Recently, a method of removing _NOx in the post-combustion region is being tried in developed countries, and it is considered to be effective both in terms of _NOx reduction rate and economical efficiency.

As a conventional method for reducing _NOx as described above, Patent Document 1 provides a three-stage combustor for exhaust gas recirculation for liquid and gas, which reduces the production amount of nitrogen oxides ( _NOx ) by reducing the amount of nitrogen oxides (NOx) produced. Unlike general air and exhaust gas, which are mixed and supplied in three stages, the mixing ratio of each stage is different in order to minimize the generation of local high temperature areas caused by multi-stage combustion, and to expand the combustion area to achieve uniform heating inside the boiler.

In the above-mentioned Patent Document 1, as elements for recirculating the exhaust gas, additional devices such as a plurality of exhaust gas supply pipes, a recirculation duct, and a damper are provided so as to re-flow the exhaust gas into the combustion furnace, However, the disadvantage is that the device needs to be additionally arranged outside the combustion furnace, so that the required space becomes larger.

On the other hand, with regard to Patent Document 2, referring to the granted patent previously filed by the present applicant, as shown in FIG. 4, an internal recirculation technique is provided, in which combustion gases 3', 4' generated in a combustion furnace 1' are provided. No additional device is required to transfer from the inside of the burner 1' to the inside of the burner 2', without passing through the external connecting passage of the burner, but the disadvantage is that the combustion gas 4 in a partial area of the burner 1' cannot be effectively utilized ' flow and does not take into account the control of fuel supply.

【Online technical literature】

【Patent Literature】

(Patent Document 1) KR 10-2005-0117417 A

(Patent Document 1) KR 10-1512352 B1

SUMMARY OF THE INVENTION

technical problem to be solved

Therefore, in order to solve the above-mentioned problems, the present invention aims to provide an ultra-low nitrogen oxide combustion device, which adopts an internal recirculation technology, which supplies the oxidant to the central area of the combustion furnace, and makes The combustion gas in the combustion furnace of the flame field is passed from the inside of the combustion furnace without additional means, rather than by the external connecting channel of the combustion furnace, which is through the smoother recirculation of the combustion gas flowing in the recirculation area in the combustion furnace And fuel distribution optimization control, improve the nitrogen oxide reduction effect.

Solutions to technical problems

In order to achieve the above object, the present invention provides an ultra-low nitrogen oxide combustion device, which includes: a combustion furnace; a burner, one side of which is inserted into the combustion furnace, and the inserted side and the outer peripheral surface The internal surfaces of the burner are spaced apart by a predetermined interval; a main fuel injector is located in the center of the burner; an auxiliary fuel injector surrounds the main fuel injector and has an end from one side end of the burner a fuel recirculation port on the outer peripheral surface of the combustor near where the end of the auxiliary fuel injection body is located; and a sensor for sensing the CO concentration contained in the combustion gas in the combustion furnace, wherein the main fuel is supplied to the combustion furnace through the main fuel injection body in an amount smaller than a preset amount and is supplied to the combustion furnace through the auxiliary fuel injection body. The combustion furnace additionally supplies auxiliary fuel, the supply amount of which is equal to the amount by which the main fuel is reduced relative to the preset amount, so as to carry out combustion in the combustion furnace, when the When the CO concentration in the combustion furnace is greater than or equal to a preset concentration, the supply amount of the main fuel is increased, which is generated by the combustion and flows between the inner peripheral surface of the combustion furnace and the outer peripheral surface of the burner The combusted gas flows into the inside of the burner through the fuel recirculation port depending on the flow rate of the auxiliary fuel injected by the auxiliary fuel injector, thereby reburning.

Preferably, an oxidant recirculation guide portion is further included, which is located between the main fuel injector and the auxiliary fuel injector, with the main fuel injector as the center, and a plurality of oxidant recirculation guides are arranged at predetermined intervals on the same circumference. Each of the auxiliary fuel injectors flows into the oxidant recirculation guide portion, and is supplied to the The oxidant of the main fuel injector is mixed and combusted with the main fuel supplied to the main fuel injector.

Preferably, the oxidant recirculation guide includes: an inner recirculation sleeve disposed obliquely with respect to the auxiliary fuel injector; a connection guide extending from a rear end of the inner recirculation sleeve; and a nozzle , which is connected to the rear end of the connecting guide for changing the moving direction of the flowing combustion gas.

Preferably, the nozzle is arranged obliquely between the main fuel injector and the oxidant recirculation guide, so that the flow space of the oxidant, that is, the main fuel injector and the oxidant recirculation guide, is reduced. width between.

Preferably, it further includes a recirculation promoting boss attached between the nozzle and the outer surface of the main fuel injector, the recirculation promoting boss increasing between the main fuel injector and the oxidant The flow rate of the combustion gas flowing between the recirculation guides.

beneficial effect

As described above, according to the ultra-low NOx combustion device according to the present invention, the internal recirculation technology is adopted, and the combustion gas generated in the combustion furnace is transferred from the interior of the combustion chamber without additional devices, without passing through the combustion chamber. External connection channel pass.

In addition, through the structure of the recirculation port that guides the smooth flow of the combustion gas, the recirculation of the combustion gas is optimized, and the combustion gas in the combustion furnace flows in a multi-stage form for smoother combustion, so that ultra-low NOx can be realized. The fuel is operated and the recirculated combustion gas is combusted with the oxidant and the fuel, thereby stabilizing the flame in the combustion furnace.

In addition, nitrogen oxides can be further reduced by optimal control of the distribution of the supplied fuel.

Description of drawings

FIG. 1 is a schematic side view of an ultra-low nitrogen oxide combustion device according to an embodiment of the present invention.

2 is a schematic side view of an ultra-low NOx combustion device according to an embodiment of the present invention, showing the combustion process of the ultra-low NOx combustion device.

3 is a schematic side view of an ultra-low NOx combustion device according to another embodiment of the present invention, showing the combustion process of the ultra-low NOx combustion device.

FIG. 4 is a schematic side view of a conventional combustion apparatus.

FIG. 5 is a flow chart showing the combustion process of the ultra-low NOx combustion device according to the present invention.

Fig. 6 shows the _NOx generation amount, the _NOx generation amount in the case where the recirculation port is not used as the conventional recirculation multi-stage combustion device (Patent Document 2), and the ultra-low gas generation amount according to the present invention The _NOx generation amount when a recirculation port is used as a nitrogen oxide combustion device.

FIG. 7 shows the NO _x generation amount, respectively showing the NO _x generation amount in the case where the fuel distribution optimization control is not employed and in the case where it is employed.

[reference number]

1: Burner

5: Burner

10: Main fuel injector

11: Main fuel injection part

21: Fuel recirculation port

20: Auxiliary fuel injector

30: Cyclone

40: Oxidant recirculation guide

41: Internal recirculation sleeve

43: Connection guide

45: Nozzle

47: Inclined member

50: Fuel Supply Department

51: First fuel supply line

52: Second fuel supply line

55, 56: Solenoid valve

60: Air multi-stage sleeve

72: The first flame space

74: Second Flame Space

76: Combustion gases in the recirculation zone

78: Premix Area

80: Oxidant supply part

85: Central oxidizer jet

90: Recirculation-promoting boss

100: Ultra-low NOx combustion device

Detailed ways

The above objects, features and other advantages of the present invention will become more apparent by detailed description of the preferred embodiments of the present invention with reference to the accompanying drawings. The described embodiments are provided as examples to illustrate the present invention, and are not intended to limit the technical scope of the present invention.

As necessary, the respective constituent elements constituting the ultra-low nitrogen oxide combustion device of the present invention may be used as an integrated type, or may be used separately from each other. In addition, depending on the usage form, some constituent elements may be omitted and used.

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

Overall structure description of ultra-low NOx combustion device

First, with reference to FIG. 1 , the overall structure of an ultra-low NOx combustion device 100 according to an embodiment of the present invention will be observed.

The ultra-low NOx combustion device 100 includes: a combustion furnace; a burner 5, one side of which is inserted into the combustion furnace; a main fuel injector 10, located in the center of the burner 5; an auxiliary fuel injector 20, Surrounding the main fuel injector 10, and its end is retracted by a predetermined interval from one end of the burner 5 toward the other side; and the oxidant recirculation guide portion 40 is located between the main fuel injection body 10 and the auxiliary fuel injection body 20 .

One side of the burner 5 is inserted into the combustion furnace 1 , and the outer peripheral edge thereof is spaced apart from the inner peripheral surface of the combustion furnace 1 by a predetermined interval.

Specifically, the burner 5 is inserted in such a manner that the front end portion 6 of the burner 5 is spaced apart from the insertion surface (the lower side surface of the burner 1 in FIG. 2 ) of the burner 1 by a predetermined interval a, so that the burner 5 can be divided into The recirculation area of the combustion gas in the combustion furnace.

The main fuel injector 10 includes a transfer portion 13 that is connected to the main fuel supply line 51 , and a main fuel injection portion 11 that is directly connected to the transfer portion 13 . The transfer portion 13 is used to safely transfer the main fuel to the main fuel injection portion 11 and may have a uniform diameter.

As an example, the main fuel injection portion 11 may have a shape whose diameter is gradually increased, and inject the supplied main fuel through the outer peripheral surface thereof. That is, the fuel that has entered the main fuel injection portion 11 through the injection holes (not shown) formed in the outer peripheral surface of the main fuel injection portion 11 is injected into the inner space between the fuel injection bodies 10 and 20 (see FIG. 2 ). Reference numeral 15). That is, the fuel in the main fuel injection portion 11 is injected onto the inflowing oxidant along the radial direction of the main fuel injection portion 11 .

On the other hand, the central oxidant injector 85 may be arranged along the interior of the main fuel injector 10 . Among them, it is configured such that a nozzle can be inserted into the distal end of the central oxidant injector 85 so that the air supply amount can be adjusted. The central oxidant injector 85 causes the oxidant supplied from the oxidant supply unit 80 to flow along the central axis of the main fuel injector 10 , and then supplies it to the primary flame space 72 , which is the center of the flame of the combustion furnace 1 .

Thereby, the mixing effect of the flame and the oxidant is promoted in the primary flame space 72 , which is the center portion of the flame, and the formation of the red flame is suppressed, thereby leading the formation of the blue flame. At the same time, the local high temperature area around the center of the flame is reduced, thereby reducing the generation of nitrogen oxides for the first time.

The auxiliary fuel injector 20 is arranged at predetermined intervals on the same circumference with the main fuel injector 10 as the center. The number of auxiliary fuel injection bodies 20 is not limited, but 6 to 12 auxiliary fuel injection bodies 20 may be arranged, and preferably 8 auxiliary fuel injection bodies 20 are arranged at the same interval. The front end of the auxiliary fuel injector 20 is retracted from one side of the burner 5 in the combustion furnace 1 to the other side.

In other words, the front end of the auxiliary fuel injector 20 is located at a predetermined interval from the front end portion 6 of the burner 5 toward the insertion surface (lower side surface in FIG. 1 ) of the combustion furnace.

The fuel injected from the auxiliary fuel injector 20 is combusted in the combustion furnace 1 and generates a swirling flow in the combustion furnace 1 .

As described above, by inserting the burner 5 deeper into the combustion furnace 1, the recirculation area of the combustion gas generated in the combustion furnace 1 is clearly divided in the combustion furnace 1, so that the combustion gas flows smoothly, and due to The above-described position of the auxiliary fuel injector 20 enables more efficient recirculation of the combustion gas to be described later.

Both the main fuel injector 10 and the auxiliary fuel injector 20 may be formed of hollow cylindrical tubes. The oxidant is supplied from the oxidant supply unit 80 to the space between the main fuel injector 10 and the auxiliary fuel injector 20 . The oxidant may be supplied to the interior of the combustion furnace 1 in a state in which axial or tangential momentum is formed by a swirler 30 at the front end of the main fuel injector 10 , or directly supplied to the combustion furnace without passing through the swirler 30 1 inside.

The low-pressure state is formed by the flow rate of the oxidizer supplied at a high speed to the space between the main fuel injector 10 and the auxiliary fuel injector 20 .

The fuel is divided into the main fuel (Main fuel) and the auxiliary fuel (2nd fuel) from the fuel supply part 50 and supplied to the main fuel injector 10 and the auxiliary fuel injector 20 . Specifically, after the fuel is removed from the fuel supply unit 50 by a filter (not shown) and sucked by a pump (not shown), it is divided into a first supply line 51 and a second supply line 52 and supplied to each fuel injection Body 10, 20. Solenoid valves 55 and 56 are provided on the supply lines 51 and 52, respectively, so that the respective fuels supplied as main fuel (main fuel) and auxiliary fuel (2nd fuel) can be appropriately supplied and blocked.

The fuel recirculation port 21 is located between the front end portion 6 of the burner 5 and the insertion surface of the burner 1 . Specifically, it is located at the position where the end of the auxiliary fuel injection body 20 is located in the form of a slit, whereby the combustion gas generated in the combustion furnace flows into the inside of the burner 5 and is directed to the auxiliary fuel injection body 20 and /Or the oxidant recirculation guide part 40 described later flows and burns to reduce nitrogen oxides contained in the combustion gas.

The oxidant recirculation guide portion 40 includes: an internal recirculation sleeve 41 (Forced Internal Recirculation Sleeve), which is arranged at an inclination on the opening (not shown) of the combustion furnace 1 with reference to the auxiliary fuel injector 20; a connecting guide 43, Extending from the internal recirculation sleeve 41; a nozzle 45 connected to the rear end of the connection guide 43 for changing the moving direction of the flowing combustion gas; and an inclined member 47 disposed obliquely inside the oxidant recirculation guide 40 lower end.

The internal recirculation sleeve 41 is arranged obliquely, and is closer to the center of the opening as it goes from the front end to the rear end of the combustor 5, which is the first inflow portion of the combustion gas. That is, the further toward the rear end of the inner recirculation sleeve 41, the smaller the inner width. The connection guides 43 are used to enable the slow flow of the combustion gas flowing in through the internal recirculation sleeve 41, which maintains a certain width.

The nozzle 45 injects the combustion gas flowing in the combustion furnace 1 through the internal recirculation sleeve 41 and the connecting guide 43 to the space between the main fuel injector 10 and the oxidant recirculation guide 40 . The injected combustion gas flows into the combustion furnace 1 together with the oxidant. The nozzles 45 are arranged obliquely between the main fuel injector 10 and the oxidant recirculation guide 40 . That is, the width between the main fuel injector 10 and the oxidant recirculation guide portion 40 is reduced, thereby realizing an orifice-like structure. The arrangement of the nozzles 45 as described above allows the oxidant supplied to the space between the main fuel injector 10 and the auxiliary fuel injector 20 to have a faster flow rate, thereby flowing into the combustion furnace 1 at a high speed.

That is, the space between the main fuel injector 10 and the nozzle 45 is narrowed, so that the flow rate of the oxidant increases according to Bernoulli's theorem. With such a configuration, the momentum of the flow generated in the combustion furnace 1 can be increased.

The inclined member 47 is a structure arranged on the boundary line between the connection guide 43 and the nozzle 45 , and adjusts the flowable width of the combustion gas, and finally adjusts the flow rate.

The air multistage jacket 60 is a hollow cylindrical structure, and is configured to separate and supply the oxidant supplied from the oxidant supply unit 80 to the inside and the outside of the air multistage jacket 60, so as to realize the multistage supply of the oxidant, and finally, it is easy to A multi-stage flame is formed inside the combustion furnace 1 .

The recirculation-promoting boss 90 is arranged on the outer peripheral surface of the air multi-stage jacket 60 . Specifically, the recirculation promoting protrusions 90 function to reduce the space between the nozzles 45 constituting the oxidant recirculation guide 40 and the air multi-stage jacket 60 . With the above configuration, the flow velocity of the combustion gas flowing from the combustion furnace 1 through the oxidant recirculation guide portion 40 is increased when passing through the vicinity of the recirculation promoting boss portion 90 . Thereby, the separation of the combustion gas that flows into the combustion furnace 1 again through the oxidant recirculation guide portion 40 is prevented, and the recirculation of the combustion gas is finally promoted.

Description of the combustion process of the ultra-low NOx combustion device

Next, with further reference to FIGS. 2 to 3 and FIG. 5 , the combustion process and effects of the ultra-low nitrogen oxide combustion device according to the embodiment of the present invention will be described.

A fuel and an oxidant are supplied to the ultra-low NOx combustion device to perform combustion ( S100 ).

Wherein, the supplied fuel is divided into main fuel and auxiliary fuel and supplied, the main fuel is supplied in an amount less than a preset amount (for example, the theoretical equivalence ratio to the oxidant), and an auxiliary fuel is additionally supplied in an amount equal to the amount of the main fuel that is less supplied .

The oxidant is supplied by the oxidant supply unit 80 , and a part of the supplied oxidant flows through the central oxidant injector 85 inside the main fuel injector 10 .

At the same time, the main fuel is supplied from the fuel supply portion 50 to the main fuel injector 10 through the first fuel supply line 51 .

The main fuel flowing in the main fuel injector 10 undergoes a process of radial injection through the outer peripheral surface of the main fuel injection portion 11 , and the injected main fuel reacts with the oxidant to form the premixing region 78 . The main fuel injection portion 11 has a shape that opens toward the combustion furnace 1 , so that the injected fuel can form a wider premixing region 78 .

The pre-mixture formed in the pre-mixing region 78 is injected into the combustion furnace 1 through the front end of the main fuel injector 10 or through the swirler 30 in a state of having axial momentum (Axial momentum) and tangential momentum (Tangential momentum) to form Burning with the first flame space.

Then, the fuel is supplied from the fuel supply portion 50 to the auxiliary fuel injector 20 through the second fuel supply line 52 . The auxiliary fuel injected by the auxiliary fuel injector 20 to the upper side of the primary flame space 72 reacts with the unreacted oxidant in the primary flame space 72 to form the secondary flame space 74 . A portion of the combustible gas in the primary flame space 72 is mixed with the premix supplied to the outer edge of the swirler 30 and moved into the wake of the primary flame to form the second flame space 74 .

The fuel injected from the main fuel injector 10 forms the primary flame space 72 based on the multi-stage air flow in the combustion furnace 1 , and the fuel injected from the auxiliary fuel injector 20 is based on the primary flame space 72 of the main fuel injector 10 . The ambient temperature and residual oxygen generated by the transferred heat undergo a partial oxidation reaction and are converted into various combustible gases, thereby forming the second flame space 74 in the flame wake. Therefore, a multi-stage flame state in the combustion furnace including the fuel-rich region and the fuel-lean region is clearly defined.

In other words, the main fuel injected along the radial direction of the main fuel injector 10 is premixed with the oxidant to form a premixed region 78 , and the premixed premix supplied from the premixed region 78 into the combustion furnace 1 forms the primary flame space 72 , and injects auxiliary fuel from the auxiliary fuel injector 20 to the rear end of the primary flame space 72 to form the final flame.

As described above, a multi-stage flame space is formed in the combustion furnace 1 by the fuel injected by the main fuel injector 10 and the auxiliary fuel injector 20 . A second flame space 74 is formed at the rear end of the first flame space 72 . The secondary flame space 74 is formed in a form that surrounds the primary flame space 72 in a space deeper inside the combustion furnace 1 .

Combustion in the multi-stage flame space including the first flame space 72 and the second flame space 74 by virtue of the low pressure formed between the main fuel injector 10 and the auxiliary fuel injector 20 due to the supply of the oxidant described above The gas 75 flows into and flows into the oxidant recirculation guide portion 40 , then flows to the side of the premixing region 78 formed between the main fuel injector 10 and the auxiliary fuel injector 20 , and is combusted in the combustion furnace 1 .

Independent of this, a recirculation region is formed in the space between the inner peripheral surface of the combustion furnace 1 and the outer peripheral surface of the burner 5 . In such a recirculation zone, the combustion gases 76 flow in a swirling flow.

The combustion gas 76 generated in the recirculation area inside the combustion furnace 1 by the above-described combustion process flows through the space between the outer peripheral surface of the burner 5 and the inner peripheral surface of the combustion furnace 1, that is, the recirculation area.

The combustion gas 76 flowing in the recirculation region flows into the fuel recirculation port 21 by virtue of the low pressure formed by the fuel injected at high speed from the front end of the auxiliary fuel injector 20 .

The combustion gas 76 flowing into the fuel recirculation port 21 in this way can be mixed with the fuel injected from the front end of the auxiliary fuel injector 20 and supplied into the combustion furnace 1 for combustion.

In addition, as another example, the inside of the combustion furnace 1 is communicated with the outer peripheral edge of the oxidant recirculation guide 40, so that a part of the combustion gas 76 flowing in the recirculation area is caused by the oxidant supplied to the oxidant recirculation guide 40. The generated low pressure flows, passes between the auxiliary fuel injectors 20 that are spaced apart from each other, flows into the oxidant recirculation guide portion 40, flows around the main fuel injector 10, mixes with the premixing region 78, and is supplied to The primary flame space 72 in the combustion furnace 1 enables combustion.

In addition, the rest of the combustion gas 76 flowing in the recirculation area flows into the combustion furnace 1 through the fuel recirculation port 21 and is combusted by the low pressure formed by the fuel injected at high speed from the tip of the auxiliary fuel injector 20 as described above. On the other hand, the combustion gas discharged from the oxidant recirculation guide 40 to the oxidant flow space increases the flow velocity through the recirculation promoting boss 90, thereby preventing separation while increasing the flow velocity of the combustion gas and the oxidant.

After the above-mentioned process, the premix and the combustion gas undergo a process of flowing into the primary flame space 72 and burning, thereby forming a flame in the combustion furnace 1 .

Then, the CO concentration in the combustion furnace 1 is sensed in real time (S200).

During the period in which the combustion as described above is being performed, the CO concentration in the combustion furnace 1 is sensed in real time by a sensor (not shown) provided in the combustion furnace 1 for monitoring.

As described above, since less main fuel is supplied and burned, incomplete combustion is more or less formed, and CO is generated. Therefore, the concentration of CO generated by incomplete combustion is sensed in real time.

And, compare the CO concentration in the combustion furnace 1 with the preset CO concentration (S300), when the CO concentration in the combustion furnace 1 is lower than the preset concentration, keep its state and continue to burn and monitor, when the combustion furnace 1 When the CO concentration inside is equal to or higher than a preset concentration, the supply amount of the main fuel is increased (S400).

FIG. 6 shows the _NOx generation amounts of the conventional recirculation multi-stage combustion device (Patent Document 2) and the ultra-low NOx combustion device according to the present invention, respectively.

FIG. 7 shows the _NOx generation amount in the case where the ultra-low NOx combustion device according to the present invention does not adopt the optimal control of fuel distribution and in the case where the optimal control of fuel distribution is adopted.

6 and 7 , it can be confirmed that the structure of the recirculation port 21 and the optimal control of the distribution of the supplied fuel can effectively prevent the generation of _NOx while reducing the load in the combustion furnace 1 .

As described above, according to the ultra-low NOx combustion device according to the present invention, the combustion gas generated in the combustion furnace is re-flowed into the combustion furnace together with the oxidant and reacts without additional power, so that it is possible to reduce the amount of fuel at the source. The nitrogen oxides produced by the oxidation of the nitrogen components are different from the existing combustion equipment, and the combustion gas is recycled through the multi-stage recirculation of the combustion gas generated in the combustion furnace. It is smooth, and a higher NOx reduction effect can be obtained by optimal control of the distribution of the supplied fuel.

Claims (5)

1. An ultra-low NOx combustion device, comprising:

a combustion furnace (1);

a burner (5) having one side inserted into the combustion furnace (1) and having an inserted side and an outer peripheral surface spaced apart from the inner surface of the combustion furnace (1) by a predetermined distance;

a main fuel injection body (10) located in the center of the combustor (5);

an auxiliary fuel injection body (20) provided so as to surround the main fuel injection body (10) and having an end portion that is retracted from one side end portion of the combustor (5) toward the other side by a predetermined interval;

a fuel recirculation port (21) located in the vicinity of a position where an end of the auxiliary fuel injection body (20) is located on the outer peripheral surface of the combustor (5);

a sensor for sensing the concentration of CO contained in the combustion gas generated in the combustion furnace (1); and

an oxidant recirculation guide (40) located between the main fuel injection body (10) and the auxiliary fuel injection body (20),

wherein the inside of the combustion furnace (1) communicates with the outer circumferential edge of the oxidant recirculation guide (40),

supplying a main fuel, which is supplied in an amount less than a preset amount, to the combustion furnace (1) through the main fuel injection body (10) to perform combustion in the combustion furnace (1) to form a first flame space,

additionally supplying an auxiliary fuel, which is supplied in an amount equal to the amount by which the main fuel is reduced with respect to the preset amount, to the combustion furnace (1) through the auxiliary fuel injection body (20) to perform combustion in the combustion furnace (1) to form a second flame space,

increasing the supply amount of the main fuel when the CO concentration in the combustion furnace (1) sensed by the sensor is above a preset concentration,

a part of the combustion gas (76) generated by the combustion and flowing between the inner peripheral surface of the combustion furnace (1) and the outer peripheral surface of the burner (5) flows into the interior of the burner (5) through the fuel recirculation port (21) depending on the flow rate of the auxiliary fuel injected by the auxiliary fuel injection body (20) to be re-combusted,

the remaining part of the combustion gas (76) flowing between the inner peripheral surface of the combustion furnace (1) and the outer peripheral surface of the burner (5) passes through a communication portion between the inside of the combustion furnace (1) and the outer peripheral edge of the oxidant recirculation guide (40) by the flow rate of the oxidant supplied between the main fuel injection body (10) and the auxiliary fuel injection body (20) and flows into the inside of the combustion furnace (1) through the oxidant recirculation guide (40) to be re-combusted,

part of the combustion gas (75) in the first and second secondary flame spaces and the combustion gas (76) flowing into the fuel recirculation port (21) side flows into the oxidant recirculation guide (40) depending on the flow rate of the oxidant supplied between the main fuel injector (10) and the auxiliary fuel injector (20), and flows into the combustion furnace (1) to be combusted.

2. The ultra low NOx combustion device of claim 1,

the auxiliary fuel injection bodies (20) are arranged on the same circumference at predetermined intervals with the main fuel injection body (10) as the center.

3. The ultra low nitrogen oxide combustion apparatus of claim 1 or 2,

the oxidant recirculation guide (40) includes:

an internal recirculation collar (41) disposed obliquely with respect to the auxiliary fuel injection body (20);

a connection guide (43) extending from a rear end of the internal recirculation sleeve (41);

and a nozzle (45) connected to a rear end of the connection guide (43) for changing a moving direction of the flowing combustion gas.

4. The ultra low NOx combustion device of claim 3,

the nozzle (45) is obliquely arranged between the main fuel injection body (10) and the oxidizer recirculation guide portion (40), thereby reducing a flow space of the oxidizer, i.e., a width between the main fuel injection body (10) and the oxidizer recirculation guide portion (40).

5. The ultra low NOx combustion device of claim 4,

further comprising a recirculation promoting protrusion (90) disposed between the nozzle (45) and an outer face of the main fuel injection body (10),

the recirculation promoting protrusion serves to increase a flow rate of combustion gas flowing between the main fuel injection body (10) and the oxidizer recirculation guide portion (40).

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