KR100838163B1 - Low nox invertor boiler system and combustion controlling methode thereof - Google Patents

Abstract

A low NOx boiler system and a combustion control method thereof are provided to restrict the generation of NOx by reducing temperature of a furnace and accurately controlling recirculation rate of exhaust gas in response to loads of the boiler. A low NOx boiler system(10) comprises a boiler body(12), a blower(22), and a control unit(30). The boiler body comprises a burner(18) having a combustion space(15) for flame combustion and an exhaust gas emission passage(28) for discharging gas after combustion, and is configured to heat up water filled inside the combustion space by the flame and discharge heated fluid to the outside. The blower having a motor rotating in a corresponding speed of a driving signal, is formed to draw in and intermix sucking air with exhaust gas from an exhaust gas recirculation passage(EGC-P) connected to the exhaust gas emission passage, and supply the mixed gas to the combustion space of the burner. The control unit senses temperature and pressure of the fluid inside the boiler body to deliver an accelerating and decelerating driving signal proportional to the sensed temperature and pressure of the fluid.

Description

LOW NOx INVERTOR BOILER SYSTEM AND COMBUSTION CONTROLLING METHODE THEREOF

1 is a front view of a low nitrogen oxide (NOx) inverter boiler according to a preferred embodiment of the present invention.

Figure 2 is a longitudinal cross-sectional view and circuit development of a low nitrogen oxide (NOx) inverter boiler according to a preferred embodiment of the present invention.

3 is a perspective view of the blower shown in FIGS. 1 and 2;

4 is a flow chart illustrating combustion intake air of a low nitrogen oxide (NOx) inverter boiler according to a preferred embodiment of the present invention.

<Description of the code | symbol about the part of drawing>

10 low nitrogen oxide (NOx) inverter boiler 12 boiler body,

13: water gauge 14: old pain

15: combustion chamber 16: association

17 water shell 18 burner

20: nozzle 22: blower

24: preheater 26: cutter

27: damper 28: exhaust gas discharge passage

29: boiler load sensor 30: control unit

31: NOx sensor 32: ADC

34: memory 36: inverter

36: control unit EGC-P: exhaust gas recirculation passage

The present invention relates to a low NOx boiler capable of maximally reducing the emission of nitrogen oxides (hereinafter referred to as "NOx"), and in particular, the amount of NOx generated is extremely reduced through exhaust gas recirculation control. A low NOx inverter boiler having a structure that can be suppressed low and a combustion control method thereof.

Typically, nitrogen oxides (NOx) are compounds of nitrogen and oxygen, and are generated by the oxidation of nitrogen in the air at high temperatures during combustion. Seven kinds are known, and the major pollution problems are nitrogen monoxide (NO) and nitrogen dioxide (NO ₂ ). Typical sources of nitrogen oxides include automobiles, aircraft, ships, industrial boilers, incinerators, and electric furnaces.

The countermeasures are strongly demanded due to the increasing trend of air pollution by NOx in exhaust gases emitted from industrial production sites, for example, factories, homes, and office buildings. It is regulated by the Enforcement Decree of the Framework Act.

As an example of the conventional technique for achieving low NOx, Patent No. 10-0427206, "Low NOx Burner and Exhaust Gas Recirculation Control Method" (hereinafter, "Patented by Sanyo Denki Kabuki Kaisha" on April 2, 2004) Patent Application Publication No. 10-2004-0012525, published on February 11, 2004, entitled "Low Nitric Oxide Combustion Method and Apparatus" (hereinafter referred to as "Public Patent"). Both the registered patent and the published patent recycle the exhaust gas (combustion complete gas) after the combustion in the burner to the burner to lower the temperature of the combustion space of the burner and finally reduce the NOx contained in the exhaust gas discharged to the outside of the flue. Technical configuration is disclosed.

The above patent is to install the exhaust gas recirculation fan (fan) in the exhaust gas recirculation passage for supplying the combustion gas (exhaust gas) generated by the operation of the burner to the combustion air to supply the exhaust gas to the combustion air of the burner Thereby lowering the temperature of the combustion gas (combustion chamber). The rotational speed of the exhaust gas recirculation fan is controlled by the output of the NOx sensor provided on the exhaust gas recirculation passage to control the recirculation rate of the exhaust gas. However, the registered patent having such a structure should install a separate circulation fan in the exhaust gas recirculation passage, and control the rotation of the two blowers by rotating the circulation fan separately from the blower that provides combustion air to the burner. There was a lot of inconvenience.

 The patent discloses an exhaust gas recirculation path between the exhaust gas passage and the suction port of the blower, and controls the rotation speed of the blower according to the output of the oxygen concentration sensor installed in the exhaust gas passage to exhaust the combustion air supplied to the burner. It is configured to reduce the NOx of the exhaust gas by adding gas, water or steam. However, the disclosed patent having such a configuration allows the rotational speed of the blower to increase or decrease according to the oxygen concentration sensed by the oxygen concentration sensor installed in the exhaust gas passage to adapt to the load of the boiler and to recycle the exhaust gas to the combustion air. This was not precisely controlled, resulting in less NOx reduction.

Accordingly, an object of the present invention is to adapt the load of the boiler to reduce the NOx of the exhaust gas by reducing the temperature of the furnace by recycling the exhaust gas from the combustion of the burner to the combustion air and the combustion control method thereof In providing.

Another object of the present invention is to reduce NOx by recycling a certain ratio of exhaust gas to combustion air of the burner according to the rotation of the blower which supplies the combustion air to the burner by the induction motor whose rotation speed is controlled by the output of the inverter. A low NOx inverter boiler and its combustion control method are provided.

Another object of the present invention is to automatically adjust the ratio of the recycle gas of the exhaust gas mixed in the combustion air supplied to the burner according to the NOx amount of the combustion complete gas discharged to the outside of the burner through the flue and the load of the boiler It is to provide a low NOx inverter boiler and its combustion control method that can reduce the NOx emissions by lowering the temperature of the burner combustion space.

The present invention for achieving the above object provides a combustion space in the combustion space and the exhaust gas discharge passage for discharging the gas after the combustion, and a flame corresponding to the mixing ratio of the input fuel and the combustion air to the combustion space. A boiler shell for heating the water filled therein by the burner and the flame of the combustion space to discharge the heated fluid; The motor is rotated at a speed corresponding to a drive signal, and the exhaust gas and the outside air are sucked and mixed through the exhaust gas recirculation passage connected to the exhaust gas discharge passage by the driving of the motor and supplied to the combustion space of the burner. Blower; And a control unit which senses the temperature / pressure of the fluid in the boiler body and provides a speed increase / deceleration drive signal to the blower in proportion to the detected pressure / temperature of the fluid.

A damper that is opened and closed in response to a damper driving signal is installed inside the exhaust gas recirculation passage to adjust the amount of recirculation of the exhaust gas to about 100%: 20% of the recycle ratio of the external air and the exhaust gas. It is desirable to.

The blower is a gas chamber having a first inlet connected to the exhaust gas recirculation passage and a second inlet formed to input external air, and is connected to the gas chamber and coupled to a combustion air port of the burner. By the rotation of an impeller (internal) located therein is fixed to the gas supply unit for supplying the air mixed with the recycled exhaust gas and the outside air to the combustion air of the burner, and the impeller of the gas supply unit, The motor is rotated at a speed according to the input of a drive signal to rotate the impeller.

The control unit includes a boiler load detection sensor for detecting the temperature / pressure of the fluid in the boiler body, a NOx sensor installed on the exhaust gas discharge passage to sense the NOx content of the exhaust gas discharged to the outside, and the load detection An analog to digital converter (ADC) for converting the output of the sensor and the NOx sensor into a digital signal, an inverter control signal for controlling the rotation of the blower at a speed corresponding to the output of the boiler load sensing sensor; A memory for storing damper drive control signals corresponding to the NOx detection signal, an inverter for providing a drive voltage of a variable voltage variable frequency (VVVF) corresponding to the inverter control signal to the electric motor; The inverter control signal corresponding to the boiler load detection signal input through the ADC and the damper driving signal corresponding to the NOx detection signal are measured. Access from Li is characterized in that it consists of a control unit for supplying a damper is installed on the inverter, and an exhaust gas recirculation passage.

The combustion control method of a low NOx inverter boiler according to another principle of the present invention corresponds to a combustion space in which a flame is combusted, an exhaust gas discharge passage for discharging the gas after combustion, and a mixing ratio of input fuel and combustion air. A burner for providing a flame to the combustion space and a boiler shell for heating the water filled therein by the flame in the combustion space to discharge the heated fluid; Combustion through exhaust gas and external air inlet through a recirculation inlet having a blower that is rotated at a speed corresponding to a drive signal and connected to the exhaust gas discharge passage by driving the blower to recirculate only a portion of the exhaust gas. A blower configured to suck and mix air for supply to the combustion space of the burner, and detect the load of the boiler as the temperature / pressure of the fluid in the boiler body; And a blower rotational speed control process for accelerating and decelerating the rotational speed of the blower in proportion to the detected boiler load.

The blower rotational speed control process includes the step of increasing the rotational speed of the blower when the load of the detected boiler is increased and the process of reducing the rotational speed of the blower when the load of the detected boiler is reduced. It features.

The low NOx inverter boiler and the combustion control method of the present invention as described above is to supply the exhaust gas recirculation passage connected to the exhaust gas discharge passage for discharging the combustion gas inside the boiler body by the ignition of the burner to the burner air. It is connected to the exhaust gas recirculation port formed at one side of the blower, and by controlling the rotational speed of the blower in proportion to the load of the boiler body, the exhaust gas is always recycled to the burner according to the load of the boiler to lower the temperature of the combustion space. As a result, generation of NOx can be suppressed.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. Although the drawings according to the embodiment of the present invention described below are applied to the structure of the furnace-associated condensing boiler, it should be noted that a perfusion boiler may be applied instead of the furnace-associated condensing boiler.

1 is a front view of a low NOx inverter boiler according to a preferred embodiment of the present invention, Figure 2 is a longitudinal sectional view and a circuit development of the low NOx inverter boiler according to a preferred embodiment of the present invention.

1 and 2, a low NOx inverter boiler 10 according to an exemplary embodiment of the present invention has a cylindrically closed structure and a boiler having a water-shell 17 formed therein. It has a body 12. One side of the boiler body 12 is opened and coupled to the burner 18, the furnace (furance) to form a combustion space 15 for burning the flame provided from the injection nozzle 20 of the burner 18 (14) is installed, the upper part of the furnace (14) (Smoke tube) for discharging the exhaust gas (combustion complete gas) filled in the interior of the furnace (14) to the outside of the boiler body ( 16) is installed.

The blower 22 is rotated at a speed in response to the input of the driving signal in the lower portion of the burner 18 to mix the gas through the first suction port and the second suction hole and supply the gas to the combustion space 15 of the burner 18. ) Is installed.

A preheater 24 is installed at an upper portion of the opening side of the tube 16 formed on the front surface of the boiler body 12, and the blower 22 is a heat of combustion complete gas (exhaust gas) discharged from the tube 16. The combustion air supplied by) is preheated and supplied to the combustion space 15 of the burner 28. The preheater 24 may use a heat pipe air pre-heater that lowers the temperature of the exhaust gas and preheats combustion air.

A flue 28 is connected to an exhaust gas outlet side of the preheater 24 through an economizer 26. The flue 28 is an exhaust gas discharge passage for discharging the combustion complete gas, that is, the exhaust gas, in the burner 18 as is well known. Inside the flue 28 is attached a NOx sensor 31 for detecting the content of NOx contained in the exhaust gas.

And between the flue 28 and the first inlet of the blower 22 exhaust gas recirculation passage (EGC) for recycling a part of the exhaust gas discharged to the flue 28 to the combustion space of the burner 18 -P: Emission Gas Recirculation Pass (PIC) is connected, and the damper 27 is operated in accordance with the damper open / close control signals (D-CTL) inside the exhaust gas recirculation passage (EGC-P). It is installed.

On one side of the boiler body 12, for example, the upper side, a water supply valve V1 and a burner 18 for supplying a fluid, for example, water, required for boiler operation to the water-shell 17. The discharge valve (V2) is provided for discharging the hot water or the steam generated in the heating by the operation of the outside to the outside of the boiler body (12).

In addition, the hot water / steam transfer pipe (SS) is connected to the outlet of the discharge valve (V2), the fluid filled in the water-shell (17) in the upper portion of the boiler body 12, that is, boiler operating water The boiler load sensor 29 is installed to detect the temperature of the steam or the pressure of the steam discharged therefrom. The boiler load detection sensor 29 is a temperature sensor or a pressure sensor depending on the type of boiler. For example, a temperature sensor is applied when the output of the final load of the low NOx inverter boiler 10 is medium temperature water, and a pressure sensor is applied when the output of the final load is output as steam.

The rotation speed RPM of the blower 22 shown in FIGS. 1 and 2 is controlled by an inverter by a control unit 30 that generates a drive signal in proportion to the output of the boiler load sensor 29, and exhaust gas. The damper 27 installed in the recirculation passage (EGC-P) is a damper driving signal (D-CTL) output from the control unit 30 for inputting the output of the NOx detection sensor 31 installed in the flue 28. It is opened and closed by).

The control unit 30 shown in FIG. 2 converts the output of the boiler load sensor 29 installed in the boiler body 12 and the output of the NOx detection sensor 31 installed in the flue 28 into digital signals. A damper drive control signal corresponding to an inverter control signal and a NOx detection signal for controlling the rotational speed of the blower 22 at a speed corresponding to the ADC 32 and the boiler load detection signal through the ADC 32. A memory 34 storing the CTL, an inverter 36 providing the VVVF drive signal corresponding to the inverter control signal to the blower 22, and a boiler load sensing input through the ADC 32; Damper 27 installed in the inverter 36 and the exhaust gas recirculation passage (EGC-P) by accessing the inverter control signal and the damper driving signal (D-CTL) corresponding to the signal and the NOx detection signal from the memory 34. The control part 38 is supplied to the furnace, respectively.

In the exemplary embodiment of the present invention, the memory 34, the ADC 32, and the controller 36 are formed of different blocks, but in the case of designing a microprocessor having an ADC input port and having a large internal memory, a one-chip processor (One Note that it can be implemented as a chip processor. Reference numeral 13 not described in FIG. 1 is a water gauge to know the level of the internal water-shell 17 of the boiler body 12.

3 is a perspective view of the blower shown in FIGS. 1 and 2. Referring to FIG. 3, the blower 22 according to the exemplary embodiment of the present invention has a first inlet 22B and external air to which the other side of the exhaust gas recirculation passage (EGC-P) connected to one side of the flue 28 is connected. A gas chamber 22A having a second suction port 22C formed for input, and an impeller communicated with the gas chamber 22A and coupled to a combustion air hole of the burner 18 and located therein. impeller of the gas supply part 22D and the gas supply part 22D which supplies the air which mixed the said recycled exhaust gas and external air to the combustion air of the burner 18 by rotation of the impeller 22F. It is composed of an electric motor 22E that is axially coupled to 22F and is rotated at a speed in response to input of a drive signal to rotate the impeller 22F. The second suction port 22C of the configuration is provided with a mesh net (mesh net) for preventing the foreign matter is sucked into the inside.

4 is a flow chart illustrating a combustion intake air control of the low NOx inverter boiler 10 according to an exemplary embodiment of the present invention, which is masked in a ROM region in the control unit 38 in the control unit 30 illustrated in FIG. 2.

Hereinafter, the operation of the low NOx inverter boiler 10 and the NOx suppression combustion process according to the embodiment of the present invention will be described in more detail with reference to FIGS. 1 to 4.

In the state in which the water shell 17 of the boiler body 12 shown in FIGS. 1 and 2 is filled with the fluid required for the boiler operation, preferably water, at an appropriate level, an igniter (ignition device is known in boiler systems). When the burner 18 is ignited when the burner 18 is activated, the electric motor 22E of the blower 22 is rotated at an initial set speed, and the ignition device (in the boiler, the ignition device is a technology for the main pipe, Is omitted), the flame is provided from the nozzle 20 of the burner 18. When the flame generated from the burner 18 is combusted in the combustion space 15, the combustion-complete gas filled in the furnace 14 of the boiler body 12, that is, the exhaust gas is associated with the associated pipe 16, the preheater 24, It is discharged to the outside through the path of the coke 26 and the flue 28.

Part of the combustion-complete gas discharged to the flue 28, that is, the exhaust gas, is recycled to the first inlet 22B of the blower 22 through the exhaust gas recirculation passage (EGC-P). A flue damper 27 is installed in the exhaust gas recirculation passage (EGC-P), and the opening amount of the damper 27 is set to recycle about 20% of the amount of exhaust gas discharged from the flue 28. have.

Meanwhile, the boiler load sensor 29 installed in the boiler body 12 of FIG. 2 detects the temperature of the fluid filled in the water-shell 17 in the boiler body 12, that is, the temperature of the hot water or the pressure of the steam. The detection signal is input to the ADC 32 in the control unit 30, and the NOx sensor 31 installed in the flue 28 is discharged from the combustion space 15 of the furnace 14 by the combustion of the burner 18. The NOx contained in the exhaust gas discharged to the outside through the associative 16, the preheater 24, and the coal mill 26 is sensed and input to the ADC 32.

The ADC 32 converts the input boiler load detection signal and the NOx detection signal into digital signals and provides them to the controller 38. In this case, the controller 38 checks the boiler load detection signal in step S1 of FIG. 4, and accesses the inverter control signal corresponding to the detected boiler load detection signal from the memory 34 to the inverter 36 in step S2. Supply. Here, the inverter control signal is for changing the voltage and frequency output from the inverter 36, and is for increasing and decreasing the rotational speed of the electric motor 22E in the blower 22 in direct proportion to the boiler load. .

For example, when the temperature of the hot water in the boiler body 12 is high or the pressure of the steam is high, an inverter control signal for reducing the rotational speed of the electric motor 22E in the blower 22 is outputted. On the contrary, if the temperature of the hot water in the boiler body 12 is low or the pressure of steam is low, the inverter loads the inverter control signal for reducing the rotational speed of the electric motor 22E of the blower 22.

The inverter 36 which inputs the inverter control signal from the controller 38 supplies the driving signal VVVF corresponding to the input inverter control signal to the motor 22E of the blower 22, and the motor 22E is driven. It is rotated at a speed corresponding to the signal.

When the electric motor 22E in the blower 22 is speeded up or slowed down by the control of the inverter 36, the impeller 22F coupled to the shaft of the electric motor 22E burns the gas in the gas supply part 22D. Blow into the combustion space of 18). At this time, one side of the gas supply unit 22D of the blower 22 is a gas chamber formed with a first inlet 22B connected to the exhaust gas recirculation passage (EGC-P) and a second inlet 22C for sucking external air. It communicates with 22A.

The exhaust gas recycled through the first inlet 22B by the driving of the blower 22 and the air for external combustion through the second inlet 22C are mixed into the combustion space 15 of the burner 18. By supplying, the combustion air of the burner 18 can be stabilized by the flow volume of mass sufficient for complete combustion. In addition, since the temperature of the flame provided from the burner 18 does not change significantly, it can be maintained at a temperature capable of sufficiently low NOx reduction, and the amount of NOx generated can be suppressed low.

In the process S2 of FIG. 4, the controller 38 controlling the rotation speed of the electric motor 22E in the blower 22 in response to the boiler load is the NOx sensor installed in the year 28 through the ADC 32 in process S3 ( Read the output of 31). Thereafter, the controller 38 compares the detected NOx amount of the exhaust gas detected by the NOx sensor 31 with a preset value in step S4 and searches whether the detected NOx detection amount exceeds a preset value. Here, the preset value is set to a value of about 60 ppm 5% and is a value that can be changed.

If it is determined that the NOx detection amount of the exhaust gas detected by the NOx sensor 31 exceeds the set value, the controller 38 determines that the exhaust gas recirculation passage (EGC-P) The amount of exhaust gas recycled to the first suction port 22B of the blower 22 is corrected by outputting a damper driving signal D-CTL for controlling the amount of opening of the damper 27 installed therein.

For example, when the NOx amount of the exhaust gas discharged to the exhaust gas discharge passage 28 exceeds the set value, the damper 27 is stepped in the opening direction through the exhaust gas recirculation passage (EGC-P). The temperature of the combustion space of the burner 18 is further lowered by increasing the recycle amount of the exhaust gas supplied to the first inlet 22B of the blower 22. By correcting the amount of recycled exhaust gas as described above, the combustion state of the burner 18 can be made more stable, and the amount of NOx generated can be suppressed more stably and lower.

In the above-described embodiment, the NOx sensor 31 is installed in the flue 28, and the amount of opening and closing of the damper 27 installed inside the exhaust gas recirculation passage EGC-P according to the output of the NOx sensor 31 is determined. Although the control configuration has been described, when the NOx sensor 31 is not installed, the damper 27 may be manually operated by replacing the damper 27 with a manual damper that is opened and closed by manual operation. In this case, only the rotation speed of the electric motor 22E of the blower 22 is controlled by the inverter by the process of S1, S2 of FIG. 4 of the control unit 38, and is proportionally adjusted according to the boiler load. The invention will even claim such technical arrangements.

 In addition, the embodiment of the present invention has been described that the boiler load sensor 29, which is composed of a fluid temperature sensor or a pressure sensor for detecting the load of the boiler installed in the boiler body 12, water-shell (17) It should be appreciated that those skilled in the art will be able to perform the same function even when installed in the hot water or steam outlet of the tank.

As described above, the low NOx inverter boiler and the combustion control method according to the embodiment of the present invention connect the exhaust gas recirculation passage to the inlet of the blower for supplying combustion air to the burner, and adapt the electric motor in the blower to the boiler load. By rotating to provide a mixture of exhaust gas and external combustion air as the combustion air of the burner, even if the load of the boiler changes, the amount of NOx generated can be more stably and lowered.

Claims (8)

In a low nitrogen oxide inverter boiler through exhaust gas recirculation, An exhaust gas discharge passage for discharging the combustion space and the gas after combustion, a burner for providing the combustion space with a flame corresponding to the mixing ratio of the input fuel and the combustion air, and the flame in the combustion space. A boiler body for heating the water filled therein to discharge the heated fluid; The motor is rotated at a speed corresponding to a drive signal, and the exhaust gas and the outside air are sucked and mixed through the exhaust gas recirculation passage connected to the exhaust gas discharge passage by the driving of the motor and supplied to the combustion space of the burner. Blower; And a control unit which senses the temperature / pressure of the fluid inside the boiler body and provides a speed increase / deceleration drive signal to the blower in proportion to the detected pressure / temperature of the fluid. Low nitrogen oxide inverter boiler. The low nitrogen oxide inverter boiler according to claim 1, wherein a damper is provided in the exhaust gas recirculation passage connected to the blower from the exhaust gas discharge passage to adjust the exhaust gas recirculation amount. According to claim 1 or claim 2, wherein the blower is a gas chamber having a first inlet connected to the exhaust gas recirculation passage and a second inlet formed for input of external air, and the gas chamber is in communication with the gas chamber for the combustion of the burner A gas supply unit which is coupled to an air hole and supplies air mixed with the recycled exhaust gas and external air to combustion air of the burner by rotation of an impeller located therein, and is axially coupled to an impeller of the gas supply unit The low nitrogen oxide inverter boiler through the exhaust gas recirculation, characterized in that for rotating the impeller is rotated at a speed according to the input of the drive signal. The method of claim 3, wherein the control unit is a boiler load sensor for sensing the load of the boiler by a change in the temperature / pressure of the fluid in the boiler body, an ADC for converting the output of the load detection sensor into a digital signal; A memory storing an inverter control signal for controlling the rotation of the blower at a speed corresponding to the output of the boiler load detection sensor, an inverter providing the motor with a VVVF drive signal corresponding to the inverter control signal, and the motor; And a control unit configured to access an inverter control signal corresponding to a boiler load detection signal input through an ADC from the memory and to supply the inverter to the inverter. The method of claim 4, wherein the boiler load detection sensor is any one of a temperature sensor for detecting the temperature of the hot water of the water-shell inside the boiler body or a pressure sensor for detecting the pressure of the steam of the water-shell. Low nitrogen oxide inverter boiler through exhaust gas recirculation. According to claim 2, wherein the control unit is a boiler load sensor for sensing the temperature / pressure of the fluid in the boiler body, and NOx is installed on the exhaust gas discharge passage to sense the NOx content of the exhaust gas discharged to the outside A sensor, an ADC for converting outputs of the load detection sensor and the NOx sensor into a digital signal, and an inverter control signal and a NOx detection signal for controlling the rotation of the blower at a speed corresponding to the output of the boiler load detection sensor A memory storing a damper drive control signal, an inverter providing the motor with a VVVF drive signal corresponding to the inverter control signal, and an inverter control signal and a NOx detection corresponding to a boiler load detection signal input through the ADC A damper drive signal corresponding to the signal is accessed from the memory to a damper installed in the inverter and exhaust gas recirculation passage. Low nitrogen oxide inverter boiler, characterized in that consisting of a control unit for supplying. A burner and a flame in the combustion space for providing the combustion space with a combustion space in which the flame is combusted, an exhaust gas discharge passage for discharging the gas after combustion, and a flame corresponding to the mixing ratio of the input fuel and combustion air; A boiler body which heats the water filled therein to discharge the heated fluid; It has a blower that is rotated at a speed corresponding to the drive signal, and is connected to the exhaust gas discharge passage by the drive of the blower for the combustion through the exhaust gas and the external air inlet through the recirculation inlet for recirculating input only a portion of the exhaust gas In the combustion control method of a low nitrogen oxide inverter boiler system having a blower for sucking and mixing air to supply the combustion space of the burner, Sensing the load of the boiler as the temperature / pressure of the fluid in the boiler body; And a blower rotational speed control process for accelerating and decelerating the rotational speed of the blower in proportion to the detected boiler load. According to claim 7, wherein the blower speed control step of increasing the rotational speed of the blower when the load of the detected boiler is increased, and the rotational speed of the blower when the load of the detected boiler is reduced Combustion control method for a low nitrogen oxide inverter boiler system characterized in that consisting of a deceleration process.

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