KR102407785B1 - Nitrogen oxide reduction system comprising an ejector - Google Patents

Abstract

The present invention relates to a burner equipped with an ejector and a nitrogen oxide reduction system including such a burner. Specifically, when supplying recirculation gas from a burner into a boiler combustion chamber, the use of an existing blower is excluded and instead the ejector provided in the burner is used. It is designed to effectively lower the temperature in the boiler combustion chamber and at the same time reduce the amount of nitrogen oxides generated.

Description

Nitrogen oxide reduction system comprising an ejector

The present invention relates to a nitrogen oxide reduction system equipped with an ejector, and specifically, in the recirculation method of supplying the recirculated gas supplied to suppress the generation of nitrogen oxides generated in the combustion process, the use of a blower is excluded and the recycle gas is instead By using a steam ejector as steam, it is possible to effectively lower the flame temperature and internal temperature in the boiler combustion chamber and at the same time reduce the amount of nitrogen oxides generated.

In general, boilers emit environmental pollutants including nitrogen oxides (NOx) in the process of burning fuel. In particular, nitrogen oxides cause a polluted environment such as photochemical smog, respiratory problems, and acid rain, which has a great adverse effect on people's lives. do. Accordingly, countries are compelled to have means for reducing nitrogen oxides in designing boilers, particularly boilers for industrial and power generation, and various nitrogen oxide reduction methods are being studied accordingly.

As an example of a nitrogen oxide reduction method, a recirculation system has been proposed to reduce nitrogen oxide by circulating the exhaust gas generated by combustion and increasing the combustion gas flow rate by lowering the combustion chamber temperature. has been recognized for its effectiveness and is being used in many boiler designs.

On the other hand, in order to recirculate exhaust gas, a separate blower has been used in the conventional boiler design. In this case, the blower serves to suck the combustion gas from the outside and guide it into the combustion chamber.

However, there has been a problem in that the use of such a blower has a limit in the effect of suppressing nitrogen oxides by lowering the combustion chamber temperature, so that the reduction rate of nitrogen oxides according to the recirculation amount is not very high.

Accordingly, there is a need to solve the problem for a means capable of replacing the blower in recirculating the exhaust gas and providing it in the combustion chamber, and the present invention has been proposed in response to this need.

Republic of Korea Patent Publication No. 10-2013-0077657 (published on Jul. 9, 2013)

An object of the present invention is to reduce the temperature in the combustion chamber more effectively than a conventional blower by using a steam ejector when recirculating exhaust gas and inducing it into the combustion chamber, thereby increasing the nitrogen oxide reduction rate.

In addition, in the present invention, since the recirculation gas sucks the recirculation gas by the jet flow of the combustion air and the secondary fuel gas by using the ejector, there is an effect of recycling the existing energy.

In addition, the present invention utilizes the effect of not only the recirculation gas but also the flow of another fluid, for example, combustion air, secondary fuel gas, or steam, and recycle gas according to the hydrodynamic characteristics of the above fluid. The purpose is to achieve the inhalation effect of

In addition, the present invention makes it possible to adjust the amount of gas or the injection range of the recirculated gas provided into the combustion chamber by regulating the injection pressure of the ejector, and through this, by adjusting the injection range of the recirculated gas according to the internal state of the combustion chamber that changes in real time. It aims to lower the generation of nitrogen oxides.

On the other hand, the technical problems of the present invention are not limited to the technical problems mentioned above, and other technical problems not mentioned will be clearly understood by those skilled in the art from the description below.

In order to solve the above problems, the nitrogen oxide reduction system for reducing nitrogen oxides according to the present invention generates a flame inside the combustion chamber using fuel gas and combustion air, and recirculates the recirculated gas from the outside of the flame to the first injection unit a burner that jets through the high-speed; a combustion chamber in which combustion is performed by the flame; and an ejector for ejecting a portion of the exhaust gas from the combustion chamber to the burner through a recirculation gas pipe.

In addition, in the nitrogen oxide reduction system, the burner includes a fuel gas injection pipe into which fuel gas is injected; Combustion air is supplied to the combustion air pipe; and a recirculation gas pipe to which the recirculation gas is supplied; may include

In addition, the nitrogen oxide reduction system further includes a steam pipe (steam) for injecting steam (steam) into the inside of the recirculation gas pipe, the recirculation gas ejected from the ejector by the steam injected from the steam pipe may be characterized in that it receives a force in the direction of the steam.

On the other hand, in the nitrogen oxide reduction system, the burner may include: a second fuel gas injection pipe into which secondary fuel gas is injected; and a second injection unit for ejecting the secondary fuel gas toward the inside of the combustion chamber at high speed. may further include.

In addition, in the nitrogen oxide reduction system, the ejector may be characterized in that at least a portion of the exhaust gas discharged from the combustion chamber by forming a low pressure therein is introduced into the burner through a recirculation gas pipe.

In addition, in the nitrogen oxide reduction system, the burner may further include a plurality of nozzles for ejecting the recycle gas in a plurality of directions.

According to the present invention, by using an ejector instead of a blower used to supply recirculation gas in a conventional boiler system, it is possible to obtain the effect of lowering the generation of nitrogen oxide more effectively compared to the conventional blower, and the amount of nitrogen oxide generated with less energy reduction effect can be obtained.

In addition, according to the present invention, it is possible to obtain the effect of more effectively lowering the temperature in the combustion chamber according to the principle of fluid mechanics by injecting the recirculation gas at a high speed by the ejector.

In addition, according to the present invention, the effect of reducing the temperature in the combustion chamber according to the principle of fluid mechanics can be more effectively obtained by enabling the ejecting effect to be obtained not only with the recirculation gas but also with another fluid such as secondary fuel and steam.

In addition, according to the present invention, since the injection pressure of the ejector can be adjusted, the recirculation gas can be appropriately injected according to the internal state of the combustion chamber through control of the injection range of the recirculation gas provided in the combustion chamber, and thus the temperature in the combustion chamber can be effectively lowered. It has the effect of being able to

Effects of the present invention are not limited to the effects mentioned above, and other effects not mentioned will be clearly understood by those skilled in the art from the following description.

1 schematically shows the structure of a conventional boiler system.
Figure 2 schematically shows a nitrogen oxide reduction system according to the present invention.
FIG. 3 shows an embodiment of a burner constituting the nitrogen oxide reduction system of FIG. 2 .
4 schematically shows a nitrogen oxide reduction system according to another embodiment of the present invention.
FIG. 5 shows an embodiment of a burner constituting the nitrogen oxide reduction system of FIG. 4 .

The purpose and technical configuration of the present invention, and details regarding the operational effects thereof will be more clearly understood by the following detailed description based on the accompanying drawings in the specification of the present invention. An embodiment according to the present invention will be described in detail with reference to the accompanying drawings.

The embodiments disclosed herein should not be construed or used as limiting the scope of the present invention. It is natural for those skilled in the art that the description including the embodiments of the present specification will have various applications. Accordingly, any embodiments described in the detailed description of the present invention are illustrative for better describing the present invention and are not intended to limit the scope of the present invention to the embodiments.

The functional blocks shown in the drawings and described below are merely examples of possible implementations. Other functional blocks may be used in other implementations without departing from the spirit and scope of the detailed description. Also, although one or more functional blocks of the present invention are represented as separate blocks, one or more of the functional blocks of the present invention may be combinations of various hardware and software configurations that perform the same function.

In addition, the expression that includes certain components is an expression of “open type” and merely refers to the existence of the corresponding components, and should not be construed as excluding additional components.

Furthermore, when it is said that a component is “connected” or “connected” to another component, it may be directly connected or connected to the other component, but it should be understood that other components may exist in between. do.

Hereinafter, a nitrogen oxide reduction system according to the present invention and a burner constituting the same will be described with reference to the drawings.

1 schematically shows a conventional boiler system, and shows a state in which a recirculation gas is supplied into a combustion chamber by using a blower.

First, a basic configuration of a boiler system will be described with reference to FIG. 1 . The boiler system largely includes a burner 101 and a combustion chamber 102. The burner 101 has a fuel injection pipe 103 to which fuel gas is supplied, and a second blower 110 for combustion in which air for combustion is supplied. The air pipe 104 and the recirculation gas pipe 106 are connected, and an exhaust gas pipe 105 for exhaust gas discharge may be connected to the lower portion of the combustion chamber 102 . On the other hand, the exhaust gas discharged through the exhaust gas pipe 105 is introduced into the exhaust gas circulation unit 107, a part is supplied to the inside of the combustion chamber along the recirculation gas pipe 106 by the first blower 109, and a part is communicated Through (108), it is possible to escape to the outside.

As described above, the recirculation gas refers to a gas that is supplied back into the combustion chamber among exhaust gases. In general, the exhaust gas has a temperature of 200~350℃. If the exhaust gas at this temperature is recirculated and introduced into the combustion chamber with an internal temperature of about 1300℃ or higher, the internal temperature of the combustion chamber can be lowered to a certain extent. The effect of reducing the amount can be obtained. In addition, since the oxygen concentration of the exhaust gas is also only 2 to 4%, when it is recirculated and supplied into the combustion chamber, it is possible to achieve the effect of lowering the generation of nitrogen oxides. During the flame in the combustion chamber, nitrogen oxides are generated in the high temperature range of 1350 ~ 1400℃ or higher. it will be possible

Meanwhile, in the conventional boiler system, as shown in FIG. 1 , at least one blower (second blower; 109) is provided to recirculate exhaust gas through the design. 1 shows a blower (second blower; 109) provided only in the exhaust gas circulation unit 107, but the blower is provided in the boiler system, such as separately installed inside and outside the recirculation gas pipe 106 It has been installed so that the recirculation gas is supplied into the combustion chamber.

However, the use of such a blower had a limit in guiding the recirculation gas to the combustion chamber, but the wind pressure by the blower was not high, so the recirculation gas was not strongly injected into the combustion chamber. There was a problem that it was not efficient.

2 and 3 show a schematic configuration and a burner 201 of a nitrogen oxide reduction system according to the present invention, respectively. For reference, the conventional embodiment of FIG. 1 was introduced as a 'boiler system', but the present invention from FIG. 2 is referred to as a 'nitrogen oxide reduction system' to emphasize that it is a system having a structure suitable for reducing nitrogen oxides.

When looking at the configurations of the nitrogen oxide reduction system according to the present invention, the burner 201, the combustion chamber 202, and the fuel injection pipe 203; the fuel injection pipe may be divided into a first fuel injection pipe and a second fuel injection pipe ), the combustion air pipe 204, the exhaust gas pipe 205, the recirculation gas pipe 206, and the communication 208 are substantially the same as the configuration in FIG. It is characterized in that an ejector 207 (ejector) is included for injecting the recirculation gas with a strong pressure. For reference, when examining the relationship between the exhaust gas circulation unit 107 in FIG. 1 and the ejector 207 in FIG. 2 , it can be understood that the ejector 207 shown in FIG. 2 is installed inside the exhaust gas circulation unit. In addition, in the drawings after FIG. 2, a description of the configuration of the exhaust gas circulation unit will be omitted.

The ejector 207 can be defined as a kind of jet pump that injects steam, compressed air, etc. from the nozzle at high speed, creates a low pressure part around it, attracts the surrounding fluid, and discharges it to a specific location. By utilizing the ejector 207, the recirculation gas is guided to the first injection unit 500 of the burner, and further, the recirculation gas is injected into the combustion chamber at high speed.

In the case of injecting the recirculation gas into the combustion chamber by using the ejector 207, technical effects can be obtained in the following points.

First, when the ejector 207 is used, there is an effect that exhaust gas can be recirculated while excluding the blower used in the existing boiler system, that is, the blower that needs to be separately powered and controlled separately, thereby reducing nitrogen oxides. There is also the effect that the system can be configured more simply. In other words, the ejector is a device that draws in the fluid from the low pressure part around it when steam or compressed air is injected at high speed. Even if there is not, it is possible to realize the recirculation of exhaust gas to the first injection unit 500 .

On the other hand, as the recirculation gas pipe 206, a separate steam pipe may be introduced from the outside to further supply steam. 500) may additionally exist to obtain a induced force. Specifically, referring to FIGS. 2 and 3 , a steam pipe is further provided in the elbow part where the recirculation gas pipe 206 is bent, so that steam from the outside has a constant pressure through the recirculation gas pipe 206. It can be sprayed inside. (Dotted arrow in FIG. 3) The steam injected into the recirculation gas pipe 206 in this way has a relatively high pressure, and when the high-pressure steam passes through a limited space at a high speed, the internal pressure is lowered according to the principle of hydrodynamics and is flowing. Other fluids around the steam, ie the recycle gas, can generate a force that moves toward the steam. That is, when viewed in terms of the flow of the recirculation gas, the recirculation gas is primarily induced in the direction of the first injection unit 500 by the ejector 207, and the force that enables the flow at this time is the ejector ( 207), and secondarily, as the steam injected from the steam pipe passes through a narrow space at a high speed, the attractive force generated by the principle of hydrodynamics is also the recirculation gas is the first injection unit 500 ) can be seen to influence the induction of In the drawings, the recirculation gas moved by the ejection force of the ejector 207 is denoted by ①, and the recirculating gas receiving the attraction by the flowing steam is denoted by ② for convenience.

Next, when the ejector 207 is used, the generation of nitrogen oxides can be more effectively lowered compared to using a conventional blower by using the hydrodynamic principle when the fluid flows at a high speed. The ejector 207 has a relatively low temperature and supplies a recirculation gas lacking oxygen into the combustion chamber, so it basically serves to lower the internal temperature of the combustion chamber and form a reducing atmosphere inside the combustion chamber at the same time. On the other hand, further here, since the recirculation gas injected at high speed from the first injection unit 500 corresponds to a fluid by itself, the internal pressure is lowered by the principle of jet flow of hydrodynamics, and the low temperature of the outside of the combustion chamber, that is, the wall of the boiler Since the temperature will drop by circulating the combustion gas of That is, there was no room for using the principle of hydrodynamics because the recirculation gas could not be injected at high speed by the conventional blower. can be lowered more effectively.

In addition, the use of the ejector 207 can lower the internal temperature of the combustion chamber by enabling a wider range of injection of the recycle gas to a point where the temperature is high even within the combustion chamber. When combustion is performed by fuel gas and air in the combustion chamber, the internal space of the combustion chamber generally exhibits an uneven temperature distribution, which may cause a point with a relatively high temperature and a point with a relatively low temperature among the internal space of the combustion chamber. prove the For example, assuming that the flame generated from the burner reaches the center of the combustion chamber, the center of the combustion chamber will be in a relatively high temperature state, but the internal space of the combustion chamber where other flames do not reach may remain in a relatively low temperature state. . At this time, when the recirculation gas is injected through the first injection unit using the ejector 207, the recirculation gas pushed by the ejector 207 may reach a high temperature point in the combustion chamber, so the high temperature point is eventually specified and the temperature It is possible to inject the recirculation gas to lower the

On the other hand, in the case of using a blower for circulation of the conventional recirculation gas, it was difficult for the recirculation gas flow in FIG. 1 (dotted arrow in the drawing) to be sufficiently supplied to the center of the combustion chamber, compared to when the ejector 207 was used. The effect of reducing the temperature had to be low, and the nitrogen oxide reduction system according to the present invention tried to solve this problem by using the ejector 207 .

Furthermore, the internal pressure of the recirculated gas injected at high speed is lowered by the principle of internal hydrodynamics, whereby a fluid having a relatively high pressure (eg, combustion gas in the combustion chamber) is moved around it, which naturally causes irregularities in the fluid. Phosphorus flow may be generated. Irregular fluid flow inside the combustion chamber caused by the recirculation gas injected at high speed can eventually induce an uneven temperature distribution inside the combustion chamber to a uniform state. It is possible to achieve the effect of suppressing the generation of oxides.

Meanwhile, referring to FIG. 3 , the first injector 500 provided in the burner 201 may be implemented to inject the recirculation gas in various directions instead of in one direction. Looking at the flow of the recirculation gas indicated in the combustion chamber of FIG. 3 , the first injection unit 500 may inject the recirculation gas in directions A, B, and C, respectively, and at this time, the first injection unit 500 is each It is possible to provide a nozzle (not shown) in the direction so that the recirculation gas is injected through each nozzle. As such, when the first injection unit 500 is provided with a nozzle capable of injection in several directions, the recirculation gas induced from the ejector 207 through the recirculation gas pipe 206 at specific points in the spaces inside the combustion chamber, respectively. By spraying, an irregular internal fluid flow can be induced. In addition, the combustion air and the secondary fuel gas may be uniformly supplied into the combustion chamber together with the recirculation gas.

4 and 5 respectively show a nitrogen oxide reduction system according to another embodiment of the present invention, and a burner constituting the same.

When looking at the configurations of the nitrogen oxide reduction system according to this embodiment, the burner 301, the combustion chamber 302, the first fuel gas injection pipe 303, the combustion air pipe 304, the exhaust gas pipe 305, the recirculation gas pipe 306 , the first injection unit 600 , the communication 308 , and the ejector 307 for injection of the recirculation gas are substantially the same as the configurations in FIG. 3 discussed above, but in this embodiment, the secondary fuel It is different in that it further includes a second fuel gas injection pipe 308 and a second injection unit 601 which are components for supplying gas into the combustion chamber.

The secondary fuel gas may be supplied into the combustion chamber at a position different from that of the primary fuel gas, and the primary fuel gas and the secondary fuel gas may be generally supplied at a constant pressure by a gas supplier. In this embodiment, since the secondary fuel gas is also injected at high pressure into the combustion chamber 302, it becomes a jet stream and sucks in the surrounding low-temperature combustion gas. That is, an ejecting effect can be obtained from the injection of the secondary fuel gas. It aims to give another ejecting effect to the recirculation gas flowing into the combustion chamber. That is, by using the ejecting effect when the secondary fuel gas supplied from the fuel gas source is injected through the second injection unit 601, the combustion chamber internal temperature reduction and nitrogen oxide reduction according to the principle of fluid mechanics It was meant to be effective.

As can be seen in FIGS. 4 and 5 , the burner 301 allows the secondary fuel gas to be injected at a position closer to the recirculation gas than the recirculation gas with respect to the point where the flame is generated by the primary fuel gas injection. It is preferable that the gas injection pipe 308 and the second injection unit 601 are designed, so that the secondary fuel gas is mixed with the primary fuel gas to easily increase the amount of combustion.

On the other hand, when the two independent injection units 600 and 601 are placed side by side and each fluid is injected at high speed, the effect of reducing the internal temperature of the combustion chamber and reducing nitrogen oxides according to the principle of fluid mechanics can be obtained more easily, which is a high-speed injection This is because, due to the low internal pressure of the recirculating gas and the low internal pressure of the secondary fuel gas during high-speed injection, the decrease in the overall fluid temperature and the movement of the relatively high-pressure fluid from the surroundings can be relatively doubled.

A methodology capable of effectively lowering the flame temperature and the internal temperature of the combustion chamber by injection of the secondary fuel gas when the recirculation gas is injected with reference to FIGS. 4 and 5 has been studied.

On the other hand, in the description of FIGS. 2 and 3 above, the point where the recirculation gas is guided to the first injection unit 500 at high pressure by the ejector 207 , furthermore, the steam injected into the recirculation gas pipe 206 . It has been discussed that the recirculation gas can be better guided to the first injection unit 500 by the hydrodynamic force, and in the description of FIGS. 4 and 5 , the recirculation gas is the secondary fuel gas in addition to the above force. The point that the flame temperature and internal temperature inside the combustion chamber can be effectively lowered by the hydrodynamic principle according to the injection was discussed. However, according to the present invention, in addition to the above-described principle, the recirculation gas also obtains a hydrodynamic force by the combustion air introduced into the inside by the second blower 210, that is, obtains an ejecting effect to better enter the combustion chamber. An induced technical effect can also be sought.

Specifically, second blowers 210 and 310 are shown in FIGS. 2 to 5 , and the second blower is for supplying combustion air at a constant pressure to the inside of the combustion chamber. That is, the combustion air also corresponds to the fluid flowing into the combustion chamber with a predetermined pressure, and in the present invention, the flame temperature inside the combustion chamber is caused by the force according to the fluid dynamics from the flow of the combustion air to the recirculation gas. and to further lower the internal temperature.

Meanwhile, in this detailed description, only the second blowers 210 and 310 are shown as means for injecting combustion air, but in some cases, the second blower is another ejector capable of supplying combustion air at a greater pressure. I understand that it can also be implemented.

The above nitrogen oxide reduction system and its constituent burners were examined. On the other hand, the present invention is not limited to the specific embodiments and application examples described above, and various modifications are carried out by those of ordinary skill in the art to which the invention pertains without departing from the gist of the invention as claimed in the claims. Of course, these modifications should not be understood as being distinct from the spirit or vision of the present invention.

101, 201, 301 burners
102, 202, 302 combustion chamber
103, 203 Fuel gas injection pipe 303 First fuel gas injection pipe
104, 204, 304 Combustion air tube
105, 205, 305 exhaust gas pipe
106, 206, 306 Recirculation Gas Pipeline
107 exhaust gas circulation unit
207, 307 ejector
108, 208, 308 flue
109 (for recirculation gas) 1st blower
110, 210, 310 (for combustion air) 2nd blower
500, 600 first injection unit
601 (for secondary fuel gas) 2nd injection part

Claims (6)

In the nitrogen oxide reduction system for nitrogen oxide reduction,
a burner for generating a flame into the combustion chamber using fuel gas and air for combustion, and injecting a recirculation gas from the outside of the flame through a first injection unit;
a combustion chamber in which combustion is performed by the flame; and
including; an ejector for ejecting a portion of the exhaust gas from the combustion chamber to the burner through a recirculation gas pipe;
The burner includes a fuel gas injection pipe into which fuel gas is injected, a combustion air pipe receiving air for combustion, and a recirculation gas pipe receiving recirculation gas,
A separate steam pipe for further injecting steam into the inside of the recirculation gas pipe is further provided in the elbow portion where the recirculation gas pipe is bent,
The recirculation gas in the recirculation gas pipe is primarily induced in the direction of the first injection unit by the injection force of the ejector, and is secondarily generated as steam is injected from the steam pipe in the direction of the first injection unit characterized in that it is guided to the first injection unit by an attractive force according to the hydrodynamic principle,
NOx reduction system.
delete delete According to claim 1,
The burner is
a second fuel gas injection pipe into which secondary fuel gas is injected; and
a second injection unit for ejecting the secondary fuel gas toward the inside of the combustion chamber at high speed;
characterized in that it further comprises,
Nitrogen oxide reduction system.
delete According to claim 1,
The burner further comprises a plurality of nozzles for ejecting the recycle gas in a plurality of directions,
Nitrogen oxide reduction system.

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